Abstract:
A facial expression control device is provided. The facial expression control device of the present invention provides multiple structures and links, wherein the links are connected to the linking assembly; therefore varies facial expressions are expressed according to the combination of the structures and links. In this way, the facial expression is changed by means of the least actuators under the condition of maintaining the number of facial expression and imitation.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial no. 100144852, filed on Dec. 6, 2011. 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 present invention is related to a control device and a robot using the control device, and more particularly, is related to a facial expression control device and a robot head using the facial expression control device. 
     2. Description of Related Art 
     The technique of emulation robot head having a humanoid appearance is proposed by Hara and Kobayashi of Tokyo Institute of Technology. They used pneumatic actuators to control the artificial facial skin fabricated by the silicone rubber. The artificial facial skin is provided with softness and flexibility, and thus the facial skin can express six basic facial expressions (surprised, frightened, sad, angry, happy and disgust) by pulling 19 control points disposed behind the facial skin. Wherein the selection of the control points are based on the facial expression coding system proposed by Ekman and 14 expression control units sufficient to compose 6 basic facial expressions are selected and used. And according to the definition, the expressions of human face can be composed from 44 groups of expression control units, i.e., the number of the expression control units determines the number of variation of expressions. Accordingly, many researchers regard this as a basis, and then the techniques related the robot head are published one after another, including the techniques of controlling facial skin variation by the methods of using memory alloy, motor, electroactive polymers (EVA) and the like, wherein the method of using motors to control facial skin for expression variation is the most commonly used. The main reason of using motors to control facial expressions is that motor has a faster response rate and uses electric power as the power source, and other assistant devices are not necessary (e.g., pneumatic compressors). 
     The well known companies who develop the related products of the emulation robot head include Kokoro of Japan, Hanson Robotic and Wow Wee of US and Xi An Superman of China. The robot heads of each of the above mentioned companies have different degree of freedom (DOF) (the expression variation) according to their different purpose. However, the expression variation mainly depends upon how many actuators have been used. In addition, the patents related to robot head include U.S. Pat. No. 7,113,848 and Japan Patent Publication No. 200235440. U.S. Pat. No. 7,113,848 discloses a humanoid face capable of facial expression including a plurality of actuators disposed in a casing, a linkage connected to the actuators and an outer skin connected to the linkage. Japan Patent Publication No. 200235440 discloses a humanoid face capable of facial expression including multiple flexible latching rings disposed at particular locations in an inner side of the skin, and the latching rings connected to the skin by a special connecting adhesive. 
     Review the currently known patents, references and products, it can be seen that, regardless of the way to achieve the facial expression, the robot head capable of facial expression generally has to use a large number of motors (e.g., 10 to 20 motors), pneumatic actuator, electric power driving memory alloy and the like to vary the controlling points of the facial skin to achieve different facial expressions. Each of the large number of actuators (motors, pneumatic actuators, electric power driving memory alloy) used in the conventional robot head operates in a way of capable to vary the position of one control point (a single degree of freedom). Thus in order that the robot head has a sufficient facial expressions (joyous, angry, sad, happy and the like), at least 12 motors is necessary to respectively drive different control point, resulting in manufacturing cost of the robot head remaining high and increase of difficulty of mechanism design and repair. The most important thing is the reliability of products may be decreased. And those reasons may be the main obstacle for the robot head capable of facial expressions to become a widespread product. 
     SUMMARY OF THE INVENTION 
     According to the currently known patents, references and products, it can be seen that, the robot head capable of facial expression generally has to use a large number of actuators to drive the controlling points of the facial skin to show variety facial expressions. And the more actuators are used, the more facial expressions the robot head has, which results in high manufacturing cost of the robot head and complex fabricating processes. Accordingly, the invention provides a simplified device which has various facial expressions with less actuator used. 
     The present invention provides a facial expression control device including a frame, a rotating element, a plurality of pushing bars, an actuator and a linking assembly. The actuator drives the rotating element to rotate, so that the pushing bars with the same length correspondingly prop against the facial expression control structures of the rotating element via the relative movement between the rotating element and the pushing bars, wherein each of the facial expression control structures may be indentations or protrusions relative to the surface of the rotating element and thereby each of the facial expression control structures has a shifting distance relative to the surface, and thus when the pushing bars prop against the facial expression control structures, the lengths protruded from the surface of the rotating element vary, and the control bars of the linking assembly are further driven to rotate. Accordingly, the control points of the facial skin linked with the control bars are driven to make the facial skin show the expression variations. 
     In light of the above, the facial expression control device in the present invention has rows of facial expression control structures with different height or depth disposed on the rotating element of the expression selecting assembly to provide a plurality of shifting distances, and by means of the cooperation of the facial expression control structures and the pushing bars with pushing or pulling the facial expression control device, the robot head using the facial expression control device can represent various facial expressions with less number of actuators. 
     In order to make the aforementioned features and advantages of the disclosure more comprehensible, embodiments with reference to accompanying drawings are described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings constituting a part of this specification are incorporated herein to provide a further understanding of the invention. Here, the drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1  is a schematic view of a facial skin of a robot head taken from the head of the robot. 
         FIG. 2  is a schematic view of a facial expression control device disposed in the head. 
         FIG. 3  is an exploded view of the facial expression control device of  FIG. 2 . 
         FIG. 4A  to  FIG. 4C  are schematic views of other embodiments of the facial expression control structures. 
         FIG. 5  is a schematic view of the facial expression control device of  FIG. 2  from another viewing angle. 
         FIG. 6  is a schematic view illustrating the linking assembly and the facial expression control device are assembled together. 
         FIG. 7  is a schematic view illustrating the pushing assembly pushing the facial expression control device. 
         FIG. 8  is a schematic view of the rotating element and the linking assembly of  FIG. 7 . 
         FIG. 9  is a schematic view of the rotating element of the first embodiment of the present invention. 
         FIG. 10  and  FIG. 11  are schematic views illustrating different control bars are pulled and rotate when limiting rings prop against different rows of the facial expression control structures. 
         FIG. 12  is a schematic view of the frame, the rotating element and the actuator of the second embodiment of the present invention. 
         FIG. 13  is a schematic view of the third embodiment of the present invention. 
         FIG. 14  is a schematic view illustrating the connecting of pushing bars and control bars of the fourth embodiment of the present invention. 
         FIG. 15  is a schematic view illustrating the connecting of pushing bars and control bars of the fifth embodiment of the present invention. 
         FIG. 16  is a schematic view illustrating the connecting of pushing bars and control bars of the sixth embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     According to the related art, based on the current technology, if the robot is required to have sufficient facial expressions, a plurality of control points are necessary to be disposed on the facial skin, and thus the required quantity of the actuators which respectively drive the control points cannot effectively be reduced. Limited by the current technology, the manufacturing cost cannot effectively reduced, and it may lead to the robot capable of various facial expressions cannot be extensively used. On the other hand, if the quantity of the actuators is reduced, the robot may have less expression variation and the robot may look inflexible. 
     Accordingly, the present invention provides a facial expression control device. A plurality of rows of facial expression control structures with different heights or depths are disposed on the rotating element of the facial expression control device to provide shifting distances. And with the cooperation of the pushing bars, the facial expression control device can show various expressions by using only one rotating element to drive the plurality of control points of the facial skin. In other words, a plurality of control points are controlled by comparatively less actuators in the present invention, so that the robot head has a plenty of facial expression variation with good emulation. The following describes the configuration of the facial expression control device of the present invention and applications. 
     First Embodiment 
       FIG. 1  is a schematic view of a facial skin of a robot head taken from the head of the robot.  FIG. 2  is a schematic view of a facial expression control device disposed in the head. Referring to  FIG. 1  and  FIG. 2  together, the robot head includes a head  110 , a facial skin (not shown), a facial expression control device  130 , a main base  132  and a pushing assembly  136 , wherein the head  110  has a cavity (not shown) used for placing the facial expression control device  130 . The main base  132  is disposed in the cavity and the facial skin covers the head  110 . The facial expression control device  130  is assembled to the main base  132  and connected with the facial skin. And the pushing assembly  136  is located relatively behind the head  110 . The pushing assembly  136  pushes the facial expression control device  130  so as to pull the control points of the facial skin to make the robot head show facial expressions. 
       FIG. 3  is an exploded view of the facial expression control device of  FIG. 2 . Referring to  FIG. 2  and  FIG. 3  together, the main base  132  of the embodiment includes a pair of first sidewalls  132   a  and a second sidewall  132   b . The first sidewalls  132   a  are substantially parallel to each other. The second sidewalls  132   b  are connected between the first sidewalls  132   a . The facial expression control device  130  is assembled on the main base  132 , and the pushing assembly  136  is assembled on the second sidewall  132   b . In addition, each of the first sidewalls  132   a  has an assembling slot  132   c  thereon, and the locations of the two assembling slots  132   c  correspond to each other so that the facial expression control device  130  is movably assembled in the assembling slots  132   c.    
     The facial expression control device  130  includes a frame  1342 , a rotating element  1344 , a plurality of pushing bars  1346  and an actuator  1348 . The frame  1342  includes a pair of third sidewalls  1342   a  and a fourth sidewall  1342   b , wherein the two third sidewalls  1342   a  are substantially parallel to each other, and the fourth sidewall  1342   b  is opposite to the second sidewall  132   b  and connected between the two third sidewalls  1342   a , and the fourth sidewall  1342   b  has a plurality of holes  1342   c . The rotating element  1344  is pivoted to third sidewalls  1342   a  of the frame  1342  and located in the space surrounded by the third sidewalls  1342   a , the fourth sidewall  1342   b  and the second sidewall  132   b . The facial expression control device  130  is pushed by the pushing assembly  136  and moves relative to the main base  132 . 
     The rotating element  1344  has at least one surface  1344   a  and a plurality of rows of facial expression control structures  1344   b  arranged in rows on the surface  1344   a , and each of the facial expression control structures  1344   b  has a shifting distance relative to the surface  1344   a . More specifically, the rotating element  1344  includes a rotating shaft  1344   c , a sleeve  1344   d , a transmission element  1344   e  and a pair of sliding elements  1344   f , wherein the sleeve  1344   d  is disposed around and fixed to the rotating shaft  1344   c , and the sleeve  1344   d  can be a cylinder or a polyhedral prism as required. In the present embodiment, the sleeve  1344   d  is a cylinder, and the surface  1344   a  and the facial expression control structures  1344   b  are disposed on the sleeve  1344   d . In other embodiments not shown in figures, the sleeve  1344   d  can be a polyhedral prism and thus the rotating element  1344  may have a plurality of surfaces connected to one after another, and multiple rows of the facial expression structures  1344   b  can be disposed on each surface according to the requirements. Moreover, the facial expression control structures  1344   b  of  FIG. 2  and  FIG. 3  are indentations (shown in  FIG. 4A ) facing the rotating shaft  1344   c  and concaving on the surface  1344   a , for example. And people who have ordinary skill in the art can design the facial expression control structures  1344   b  according to the actual demand with the protrusions (shown in  FIG. 4B ) protruding from the surface  1344   a  toward the direction relatively away from the rotating shaft  1344   c , or with the combination of the indentations and the protrusions (shown in  FIG. 4C ). All of the above mentioned methods can achieve the functions and purpose of the facial expression structures  1344   b.    
     As described above, the transmission element  1344   e  is disposed around the rotating shaft  1344   c  located beside the sleeve  1344   d , wherein the transmission element  1344   e  contacts with the actuator  1348  fixed on the frame  1342 , so that when the actuator  1348  is driven, the transmission element  1344   e  is rotated by the actuator  1348  and thereby drives the rotating shaft  1344   c  and the sleeve  1344   d  to rotate. The second ring  1344   f  is disposed around the rotating shaft  1344   c  and located at the two sides of the sleeve  1344   d . The main base  132  further has a pair of sliding slots  132   d  overlapped with a portion of the assembling slot  132   c . Each of the sliding elements  1344   f  has a protruding portion  1344   g , and the protruding portions  1344   g  are respectively located in the sliding slots  132   d . The sliding slot  132   d  can be formed on the assembling plate  150 , wherein the location of the assembling plate  150  corresponds to the location of the assembling slot  132   c , and the sliding slot  132   d  is assembled on the first sidewall  132   a  of the main base  132 . 
     In addition, the pushing bars  1346  are arranged in a row and respectively passing through the holes  1342   c  of the fourth sidewall  1342   b  of the frame  1342 , and further respectively prop against to one row of the facial expression control structures  1344   b  disposed on the surface  1344   a  of the rotating element  1344 . Additionally, the quantity of the facial expression control structures  1344   b  of each row is different or not, wherein the quantity of the facial expression control structures  1344   b  is the same in every row in this embodiment. The number of the pushing bars  1346  can be less than or equal to the number of the facial expression control structures  1344   b  of each row according to actual requirements. In other words, the sleeve  1344   d  of the rotating element  1344  is modulized in fabrication, and thus the quantity of facial expression control structures  1344   b  of each row is predetermined. In order to meet the demand of number of expressions of every robot head, the quantity of pushing bars  1346  can be changed. For example, if a robot head having facial expressions with variety and diversification is needed, the largest number of pushing bars  1346  is equal to the number of facial expression structures  1344   b  of each row; and if the robot head having facial expressions is required to have comparatively less expressions, the control points which drives the facial skin (not shown) can be reduced and thus the number of pushing bars  1346  can be less than that of the facial expression control structures  1344   b  of each row. 
     In addition, regardless of the facial expression control structures  1344   b  being the indentations concaving to the surface  1344   a  or the protrusions protruding from the surface  1344   a , the distances of ends of any two adjacent facial expression control structures  1344   b  relative to the surface  1344   a  may vary, so that the facial skin (not shown) can show much more facial expressions. In more detailed, any two adjacent facial expression control structures  1344   b  can both be the protrusions (or indentations), and the distances of the ends of any two adjacent protrusions (or indentations) relative to the surface  1344   a  are the same or different. Moreover, any two of the adjacent facial expression control structures  1344   b  can be a protrusion and a indentation, and the distance between the top terminal of the protrusion and the surface  1344   a  and that between the indentation and the surface  1344   a  can also be the same or different. 
       FIG. 5  is a schematic view of the facial expression control device of  FIG. 2  from another viewing angle. Referring to  FIG. 2 ,  FIG. 3  and  FIG. 5 , the pushing assembly  136  is disposed on the second sidewall  132   b  of the main base  132  and located relatively behind the head  110  (shown in  FIG. 1 ). And the pushing assembly  136  is connected with the facial expression control device  130 . And through the cooperation of the facial expression control device  130  and the sliding slots  132   d , the pushing assembly  136  can push the facial expression control device  130  to move relative to the main base  132 . More specifically, the pushing assembly  136  includes an actuator  136   a  and a linking assembly  136   b , wherein the actuator  136   a  is a motor and disposed on the second sidewall  132   b . The linking assembly  136   b  includes a first linkage  136   c  and a second linkage  136   d . The first linkage  136   c  is pivoted between the third sidewalls  1342   a  of the facial expression control device  130 . An end of the second linkage  136   d  is connected to the actuator  136   a  and the other end of the second linkage  136   d  is connected to the first linkage  136   c . And when the actuator  136   a  is actuated, the second linkage  136   d  pushes or pulls the first linkage  136   c , so that the facial expression control device  130  can move relative to the main base through the cooperation of the protruding portion  1344   g  and the sliding slot  132   d . Herein the second linkage  136   d  of the present embodiment is composed of two connecting rods. In other embodiments not shown in figures, the second linkage  136   d  can be a single rod. 
     Referring to  FIG. 2  and  FIG. 3 , the linking assembly  138  is disposed on the main case  132  and located relatively ahead the head  110  (shown in  FIG. 1 ). The facial expression control device  130  is located between the pushing assembly  136  and the linking assembly  138 , wherein the linking assembly  138  includes a plurality of control bars  138   a . The axial direction A 1  of the control bar  138   a  and the axial direction A 2  of the pushing bar  1346  are perpendicular to each other. And the control bars  138   a  drive the linking movement between the pushing bars  1346  and the facial skin (not shown), and thus the movements of the control bars  138   a  drive the facial skin (not shown) to show expressions. In this embodiment, latching rings  140  (shown in  FIG. 1 ) connected to the control bars  138   a  are disposed in the facial skin (not shown) to influence the facial skin. 
       FIG. 6  is a schematic view illustrating the linking assembly and the facial expression control device are assembled together. Referring to  FIG. 3  and  FIG. 6  together, specifically, the linking assembly  138  includes the plurality of control bars  138   a  mentioned above, a plurality of limiting rings  138   b , a plurality of springs  138   c , a first assembling plate  138   d , a rotating shaft  138   e , a plurality of first wires  138   f , a plurality of second wires  138   g  and a second assembling plate  138   h . The limiting rings  138   b  are respectively disposed around the pushing bars  1346  to restrict the depth of the pushing bars  1346  relative to the fourth sidewall  1342   b . The springs  138   c  are respectively disposed around the end of pushing bars  1346  relatively away from the rotating element  1344  and prop against between the first assembling plate  138   d  of the frame  1342  and the limiting rings  138   b . The rotating shaft  138   e  is pivoted between the two third sidewalls  1342   a  of the frame  1342 . The rotating shafts  138   e  penetrates through the control bars  138   a  and such that the control bars  138   a  are pivoted upon the rotating shaft  138   e  as the control bars  138   a  driven by the pushing bars  1346 . The second assembling plate  138   h  is located between the frame  1342  and the first assembling plate  138   d , and the pushing bars  1346  are passing through the second assembling plate  138   h . An end of each first wire  138   f  is respectively fixed to one of the control bar  138   a , and passing through the second assembling plate  138   h , and the other end of each first wire  138   f  is fixed to the limiting ring  138   b . In this way, the first wires  138   f  pull the corresponding control bars  138   a  to rotate according to the length formed by the pushing bar  1346  protruding from the surface  1344   a  of the rotating element  1344 . An end of each second wire  138   g  is respectively fixed to one of the control bars  138   a , and a latching ring  140  (shown in  FIG. 1 ) is disposed on the other end of each second wire  138   g . And the latching rings  140  further latch to the latching ring (not shown) disposed within the facial skin (not shown), and thus the second wire  138   g  can pull the control point of the facial skin (not shown) according to the rotating angle of the control bar  138   a.    
     The following describes in detail how the facial expression control device  130  drives the facial skin (not shown) to show expressions. 
     Referring to  FIG. 3 ,  FIG. 5  and  FIG. 6 , when the pushing assembly  136  is not driven, the first linkage  136   c  is located relatively near the second sidewall  132   b  of the main base  132 , and a distance is between an end of the pushing bars  1346  of the facial expression control device  130  relatively away from the linking assembly  138  and the rotating element  1344 . In the meanwhile, the control bars  138   a  of the linking assembly  138  are not driven, and thus the axial direction A 1  of each control bar  138   a  is perpendicular to the axial direction A 2  of the pushing bars  1346 . Additionally, there may no facial expression control structure  1344   b  disposed on a portion of the surface  1344   a  of the rotating element  1344 , and the pushing bars  1346  prop against the location where no facial expression control structure  1344   b  is disposed thereon of the surface  1344   a . Furthermore, when the robot head has no expression, the axial direction A 1  of the control bars  138   a  and the axial direction A 2  of the pushing bars  1346  being perpendicular to each other is only one of the possible embodiments. In other embodiments, the axial directions A 1  of the control bars  138   a  and the axial direction A 2  of the pushing bars  1346  may not be perpendicular to each other. 
       FIG. 7  is a schematic view illustrating the pushing assembly pushing the facial expression control device.  FIG. 8  is a schematic view of the rotating element and the linking assembly of  FIG. 7 .  FIG. 7  and  FIG. 8  are in different viewing angles. Referring to  FIG. 3 ,  FIG. 6 ,  FIG. 7  and  FIG. 8 , when the facial expression control device  130  is driven, the rotating element  1344  is driven to rotate by the actuator  1348  driving the transmission element  1344   e . Then, one of the rows of facial expression control structures  1344   b  is aligned correspondingly to the pushing bars  1346 . In the meanwhile, the actuator  136   a  of the pushing assembly  136  is driven, the first linkage  136   c  drives the second linkage  136   d  to push the facial expression control device  130  to move forward, the protruding portions  1344   g  of the sliding elements  1344   f  respectively slides in the assembling slots  132   c , and the pushing bars  1346  prop against the facial expression control structures  1344   b  of the rotating element  1344  respectively. Since the distances of the ends of the facial expression control structures  1344   b  relative to the surface  1344   a  vary, the lengths of the pushing bars  1346  protruded from the surface  1344   a  of the rotating element  1344  also vary. And in the meanwhile, the first wires  138   f  are pulled by the pushing bars  1346  and drive the control bars  138   a  to rotate by taking the rotating shaft  138   e  as a rotating center. Herein the rotating angle of the control bars  138   a  is related to the shifting distances that the ends of the facial expression control structures  1344   b  relative to the surface  1344   a , and the second wires  138   g  are affected by the rotation of the control bars  138   a , and the latching rings  140  located at the ends of the second wires  138   g  further drive the corresponding control point disposed on the facial skin (not shown), and the facial skin (not shown) is pulled to show expressions. 
     When the pushing assembly  136  pulls back the facial expression control device  130  to return to the original position, the springs  138   c , which are compressed by a distance changing between the limiting rings  138   b  and the first assembling plates  138   d  due to the movement of the pushing bars  1346 , may drive the limiting rings  138   b  back to the original position due to its own resilience. 
       FIG. 9  is a schematic view of the rotating element of the first embodiment of the present invention.  FIG. 10  and  FIG. 11  are schematic views illustrating different control bars are pulled and rotate when limiting rings prop against different rows of the facial expression control structures. Referring to  FIG. 9 , the facial expression control structures  1344   b  on different rows result in different expression shown by the facial skin (not shown). For example, the pushing bars  1346  shown in  FIG. 7  and  FIG. 8  are respectively inserted into the row of facial expression control structures  1344   b  labeled as a 1  shown in  FIG. 9 , and this results in that the robot head shows a facial expression. However, when the pushing bars  1346  are respectively inserted into the row labeled as a 2  or a 3  or other row of the facial expression control structures  1344   b , the control bars  138   a  are pulled and thus the robot head shows another expression according to the row of the facial expression control structures  1344   b  which the pushing bars  1346  inserted therein, the facial expressions are illustrated as shown in  FIG. 10  or  FIG. 11 . 
     As described above, in the facial expression control device  130  of this embodiment, only one actuator  1348  is necessary to drive the rotating element  1344  to rotate, and the pushing bars  1346  can further respectively prop against the facial expression control structures  1344   b  cooperated with the pushing assembly  136  pushing the facial expression control device  130  to drive the linking assembly  138  to pull the facial skin (not shown), wherein the number of control points to influence the facial expressions is determined according to the number of pushing bars  1346  and the number of facial expression control structures  1344   b  disposed on the rotating element  1344 . Furthermore, the number of each row of facial expression control structures  1344   b  can be changed according to the requirements, and thus the number of the facial expression control structures  1344   b  can be increased to facilitate the facial skin (not shown) to show much more various expressions with good emulation. 
     Compared to the facial skin of the conventional robot head needs a large quantity of actuators to drive the control points, thus the manufacturing cost of the conventional robot head is rather expensive. Since less actuator is used in the robot head of the present invention to control the plurality of control points of the facial skin, the more facial expressions of the robot head with diversity and good emulation is achieved, and the manufacturing cost is also effectively reduced. 
     Second Embodiment 
       FIG. 12  is a schematic view of the frame, the rotating element and the actuator of the second embodiment of the present invention. Referring to  FIG. 3  and  FIG. 12 , though only one actuator  1348  is used to directly control one rotating element  1344  in the above mentioned embodiment, in order to increase the diversity of the facial expressions, one rotating element  2344  separated into two parts are used in this embodiment and other mechanical driving methods, for example, linkage, gear or combination thereof are used, so that one actuator  1348  can simultaneously drive the two rotating elements  2344 , and the rotating directions of the two parts of the rotating element  2344  may be the same or opposite, and at the same time the rotating angles of the two parts of the rotating element  2344  can be the same or different. In this way, the facial expression control structures  2344   b  of the rotating elements  2344  can have much more combinations, and thus the robot head can have much more expression variations. 
     Third Embodiment 
     In addition, though one row of the pushing bars and one row of the facial expression control structures are used in the description of the first embodiment, by this teaching people who have ordinary skill in the art may derive to other modifications according to the actual requirements. For instance, more rows of the pushing bars  1346  and more rows of the facial expression control structures  1344   b  can be disposed.  FIG. 13  is a schematic view of the third embodiment of the present invention. Referring to  FIG. 13 , the rotating element  1344 ′ is a polyhedral prism. In  FIG. 13 , the included angle formed between any two adjacent edges  1344   a ′ and  1344   a ″ of the cross-sectional of the polyhedral prism are the same, and two rows of the facial expression structures  1344   b ′ can be disposed on each of the edges  1344   a ′ (or  1344   a ″). And the two pushing bars  1346  are respectively inserted into the two rows of the facial expression control structures  1344   b ′ of the rotating element  1344 ′. Correspondingly, the linking assembly  138  (shown in  FIG. 3 ) and the pushing bars  1346  are respectively disposed, wherein the two linkage assemblies  138  are disposed with top and bottom being symmetric but the protruding directions of the control bars  138   a  (shown in  FIG. 3 ) are opposite. Accordingly, by using only one rotating element  1344 ′ the number of the control points of the facial skin (not shown) connected thereto is increased. 
     In such configuration, the quantity of combinations of expression variations can be increased and thus the robot head can show much more expressions with diversity and a good emulation. 
     Additionally, wires are used in the connecting structure between the pushing bars and the control bars described in the first, second and third embodiments, but the connection between the pushing bars and the control bars can be modified in other embodiments within the spirit of driving the pushing bars and the control bars of the present invention. The following describes another three of the possible embodiments. 
     Fourth Embodiment 
       FIG. 14  is a schematic view illustrating the connecting of pushing bars and control bars of the fourth embodiment of the present invention. Referring to  FIG. 14 , in this embodiment, each of the control bars  338   a  has a plurality of threading holes  338   b , and the second wire  138   g  (shown in  FIG. 6 ) can pass through one of the threading holes  338   b  disposed on one of the control bars  338   a  according to the requirements. The extent of the control point of the facial skin (not shown) is influenced by which one of the threading hole  338   b  is passed through by the second wire  138   g , so that the expression shown by facial skin (not shown) may vary imperceptibly according to the extent of the control point being pushed or pulled. In addition, the pushing bars and the pushing bars are connected by latching. More specifically, an end of each of the control bars  338   a  relatively near to the pushing bars  1346  has a first latching structure  338   c , and an end of each of the pushing bars  1346  relatively near to the control bars  338   a  has a second latching structure  1346   a , wherein the first latching structure  338   c  is a latching slot and the second latching structure  1346   a  is a latching shaft, so as to latch the first latching structure  338   c  and the second latching structure  1346   a  together. 
     In this way, when the pushing bars  1346  move relative to the second assembling plate  138   h , through the cooperation of the first latching structure  338   c  and the second latching structure  1346   a , the control bars  338   a  may rotate by taking the rotating shaft  138   e  as a rotating center and further drive the facial skin (not shown) to show expressions. 
     Fifth Embodiment 
       FIG. 15  is a schematic view illustrating the connecting of pushing bars and control bars of the fifth embodiment of the present invention. Referring to  FIG. 15 , the difference between this embodiment and the fourth embodiment is that: the control bars and the pushing bars are connected by linkages. More specifically, an end of each of the pushing bars  2346  relatively near to the control bars  338   a  is a linkage  2346   a . When the pushing bars  1346  approach to the control bars  338   a  along with the axial direction A 2 , the linkage  2346   a  connected with the control bars  338   a  may drive the control bars  338   a  to rotate by taking the rotating shaft  138   e  as a rotating center. 
     Sixth Embodiment 
       FIG. 16  is a schematic view illustrating the connecting of pushing bars and control bars of the sixth embodiment of the present invention. Referring to  FIG. 16 , the difference between this embodiment and the fourth and fifth embodiment is that: the control bars and the pushing bars are connected by gears and racks. More specifically, an end of each of the control bars  438   a  relatively near to the pushing bars  3346  is a gear  438   c , and an end of each of the pushing bars  3346  relatively near to the control bars  438   a  is a rack  3346   a , and the gear  438   c  and the rack  3346   a  are engaged to each other. When the pushing bars  3346  move relative to the control bars  438   a  along the axial direction A 2 , the cooperation of the rack  3346   a  and the gear  438   c  makes the control bars  438   a  to rotate by taking the rotating shaft  138   e  as a rotating center. By using the configuration of gear  438   c  and rack  3346   a , the rotating angle of the control bars  438   a  can be precisely controlled. 
     In light of the foregoing, in the facial expression control device and robot head using the same of the present invention, only one actuator is used to drive the rotating element to rotate, with the cooperation of heights or depths formed by the pushing bars respectively propping against the facial expression control structures, and by means of the cooperation of the pushing assembly pushing the facial expression control device for driving the linking assembly to drive the facial skin, the robot head further shows varied facial expressions. Compared to the conventional robot head, since the control points controlled by less actuator with the robot head shows a plenty of facial expressions with good emulation, and thus the number of actuators is reduced compared to the conventional robot and the manufacturing cost of the robot head is also effectively reduced. And the robot heads can further be produced with modulization so that the whole fabricating cost of the robot head can be reduced and it facilitates the popularity of the robot. 
     Furthermore, the quantity of each row of facial expression control structures can be changed according to the requirements, and the configuration of the facial expression control structures and the pushing bars and the connecting between the pushing bars and the control bars can also be changed according to the requirements, and thus the facial expressions are sufficient with good emulation and the facial skin having more expression variations without changing the quantity of actuators, and the design of the facial expressions is further flexible. 
     Although the invention has been described with reference to the above embodiments, it will be apparent to one of the ordinary skill in the art that modifications to the described embodiment may be made without departing from the spirit of the invention. Accordingly, the scope of the invention will be defined by the attached claims not by the above detailed descriptions.