Abstract:
An exemplary contour measuring method for measuring aspects of objects includes: (1) providing a contour measuring probe ( 10 ) comprising a tip extension ( 16 ), a displacement sensor ( 19 ), and a processor ( 119 ) connected to the displacement sensor, the tip extension being slidable in a first direction; (2) driving the tip extension to move so as to contact with the object at a first predetermined point, and recording a coordinate of the first predetermined point in the processor; (3) driving one of the tip extension and the object to move, thus, the tip extension contacting with the object at a second predetermined point, the displacement sensor sensing a displacement of the tip extension along the first direction and sending the displacement to the processor, and the processor recording a coordinate of the second predetermined point; and (4) repeating the step (3), the processor recording a series of measured coordinates of points.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is related to nine co-pending U.S. patent applications, which are: application Ser. No. 11/611,724, filed on Dec. 15, 2006, and entitled “DISTANCE MEASURING PROBE WITH AIR DISCHARGE SYSTEM”, application Ser. No. 11/843,664, filed on Aug. 23, 2007, and entitled “CONTOUR MEASURING DEVICE WITH ERROR CORRECTING UNIT”, application Ser. Nos. 11/966,951 and 11/966,952, and both entitled “CONTOUR MEASURING PROBE”, application Ser. No. 11/966,954, and entitled “CONTOUR MEASURING PROBE FOR MEASURING ASPECTS OF OBJECTS”, application Ser. No. 11/966,957, and entitled “CONTOUR MEASURING METHOD FOR MEASURING ASPECTS OF OBJECTS”, application Ser. No. 11/966,964, and entitled “MEASURING DEVICE FOR MEASURING ASPECTS OF OBJECTS”, application Ser. No. 11/966,961, and entitled “MEASURING DEVICE AND METHOD FOR USING THE SAME”, and application Ser. No. 11/966,959, and entitled “BASE AND CONTOUR MEASURING SYSTEM USING THE SAME”. In Ser. No. 11/611,724, Ser. No. 11/843,664, Ser. No. 11/966,951, and Ser. No. 11/966,957, the inventors are Qing Liu, Jun-Qi Li, and Takeo Nakagawa. In Ser. Nos, 11/966,961, 11/966,964, 11/966,959 and 11/966,952, the inventors are Qing Liu and Jun-Qi Li. In Ser. No. 11/966,954, the inventors are Jian-Bin Kong, and Qing Liu. In Ser. No. 11/611,724 and Ser. No. 11/843,664, the assignee is Hon HAI PRECISION INDUSTRY CO. LTD and FINE TECH Corporation, and the assignee of other applications is HONG FU JIN PRECISION INDUSTRY (ShenZhen) CO., LTD and Hon HAI PRECISION INDUSTRY CO. LTD. The disclosures of the above identified applications are incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to contour measuring methods for measuring aspects of objects, and more particularly to a contour measuring method for ultraprecise measuring aspects of objects. 
   2. Discussion of the Related Art 
   A typical contour measuring method uses a contact probe as its measuring element. Referring to  FIG. 12 , the measuring device  90  includes a magnetic core  91 , a coil  92 , a fulcrum  93 , a level  94 , and a measuring tip  95 . A distal end of the measuring tip  95  always contacts with a surface of a workpiece  96 . The contour measuring method includes the following steps: (1) driving the workpiece  96  to move along an X-axis; (2) the measuring tip  95  moves along a Z-axis because the workpiece  96  has a curved surface, thus the level  94  rotates about the fulcrum  93 ; (3) the magnetic core  91  moves in the coil  92 , this movement of the magnetic core  91  induces a current in the coil  92 ; (4) The current flows into the managing circuit  97  and the managing circuit  97  amplifies and transforms the current into a digital value that is used as a signal to the computer  98 ; (5) the computer  98  calculates a displacement of the magnetic core  91  according to the digital signal, thus indirectly determining a displacement of the measuring tip  95 . 
   However, the above-described contour measuring method has the following disadvantages. Firstly, an error is generated in each of the conversions of converting ordinates of the aspect of the workpiece  96  to displacements of the measuring tip  95 , to displacements of the magnetic core  91 , to the inductance signals, and to digital signals. Thus, a cumulative error is very large in the contour measuring method. Secondly, a non-linear error is generated when the coil  92  works in a non-linear region of the coil  92 . Thirdly, a measuring scope is very small because of the non-linear region of the coil  92 . 
   Therefore, a contour measuring method for measuring aspects of objects which have high precision are desired. 
   SUMMARY 
   An exemplary contour measuring method for measuring aspects of objects includes: (1) providing a contour measuring probe comprising a tip extension, a displacement sensor, and a processor connected to the displacement sensor, the tip extension being slidable in a first direction, and the displacement sensor used to sense a displacement of the tip extension, and the tip extension always contacting with a surface of the object; (2) driving the tip extension to move so as to contact with the surface of the object at a first predetermined point, and recording a coordinate of the first predetermined point in the processor; (3) driving one of the tip extension and the object to move, thus, the tip extension contacting with the surface of the object at a second predetermined point, the displacement sensor sensing a displacement of the tip extension along the first direction and sending the displacement to the processor, and the processor recording a coordinate of the second predetermined point; and (4) repeating the step (3), the processor recording a series of measured coordinates of predetermined points. 
   Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present contour measuring method for measuring aspects of objects. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views, and all the views are schematic. 
       FIG. 1  is a top plan, cross-sectional view of a contour measuring probe in accordance with a first embodiment applied in a contour measuring method for measuring aspects of objects of the present invention, and the contour measuring probe including a pair of hollow tubes and a pair of pipes. 
       FIG. 2  is a side, cross-sectional view of the contour measuring probe of  FIG. 1 . 
       FIG. 3  is an isometric view of an exemplary application of the contour measuring probe of  FIG. 1 . 
       FIG. 4  is a comparing chart showing measuring values and predetermined ideal values from the present contour measuring method. 
       FIG. 5  is a chart showing difference between the measuring values and predetermined ideal values of  FIG. 5 . 
       FIG. 6  is a top plan, cross-sectional view of a contour measuring probe in accordance with a second embodiment applied in a contour measuring method for measuring aspects of objects of the present invention, and the contour measuring probe including a pair of hollow tubes and a pair of pipes. 
       FIG. 7  is a cross-sectional view of the contour measuring probe of  FIG. 6 . 
       FIG. 8  is a force analysis view of hollow tubes of the contour measuring probe of  FIG. 6 . 
       FIG. 9  is a top plan, cross-sectional view of a contour measuring probe in accordance with a third embodiment applied in a contour measuring method for measuring aspects of objects of the present invention, and the contour measuring probe including a pair of hollow tubes and a pair of pipes. 
       FIG. 10  is a top plan, cross-sectional view of a contour measuring probe in accordance with a fourth embodiment applied in a contour measuring method for measuring aspects of objects of the present invention, and the contour measuring probe including a pair of hollow tubes and a pair of pipes. 
       FIG. 11  is a top plan, cross-sectional view of a contour measuring probe in accordance with a fifth embodiment applied in a contour measuring method for measuring aspects of objects of the present invention, and the contour measuring probe including a pair of hollow tubes and a pair of pipes. 
       FIG. 12  is a schematic view of a conventional measuring device. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
   A contour measuring method of the present invention preferably applies a contacting measuring device. 
   Referring to  FIGS. 1 and 2 , a contour measuring probe  10  in accordance with a first embodiment is shown. The contour measuring probe  10  includes a base  11 , a tube guide  12 , two hollow tubes  14 , a first tube frame  15 , a tip extension  16 , a second tube frame  17 , a linear measuring scale  18 , a displacement sensor  19 , a pipe holder  110 , two pipes  111 , and a processor  119 . The hollow tubes  14  and the first and second frames  15 ,  17  cooperatively form a movable rack (not labeled). 
   The base  11  is substantially a flat rectangular sheet. It should be understood that the base  11  may alternatively be any other suitable shapes. The tube guide  12  is securely mounted onto the base  11 . The tube guide  12  has a front end and a rear end. The tube guide  12  defines two tube chutes  13  each extending from the front end to the rear end. The tube chutes  13  are spaced apart from, and aligned parallel to each other. 
   Each of the hollow tubes  14  is a cylinder defining a cavity  142  that extends through the hollow tube  14  from a rear open end of the hollow tube  14  to a front cylinder base  140  of the hollow tube  14 . Each hollow tube  14  is received through a corresponding tube chute  13  of the tube guide  12 . The rear open ends of the hollow tubes  14  protrude out from the rear end of the tube guide  12  and are fixed onto the second tube frame  17 . The cylinder bases  140  of the hollow tubes  14  protrude out from the front end and are fixed onto the first tube frame  15 . An outer diameter of the hollow tubes  14  is configured to be smaller than a diameter of the tube chutes  13 , so that a gap (not labeled) is defined between each hollow tube  14  and the tube guide  12 . Air is continuously pumped into the gap between the hollow tubes  14  and the tube guide  12  at a predetermined rate. Thus, an air bearing (not labeled) is formed between each hollow tube  14  and the tube guide  12  when the gaps are filled with air. 
   Each of the pipes  111  is partially inserted into the open end of a corresponding hollow tube  14 . An outer diameter of the pipes  111  is smaller than an inner diameter of the cavities  142  of the hollow tubes  14 , so that a gap  118  is defined between each pipe  111  and the corresponding hollow tube  14 . An air bearing (not labeled) is formed between each pipe  111  and the corresponding hollow tube  14  when air is pumped into the cavities  142  of the hollow tubes  14  via the pipes  111 . Therefore, friction between the hollow tubes  14  and the tube guide  12 , and between the pipes  111  and the hollow tubes  14 , is significantly small correspondingly. As a result, the hollow tubes  14  are able to move smoothly in the tube chutes  13  correspondingly. It should be understood that the gaps  118  may be omitted, and as an alternative, a lubricant can be applied between the pipes  111  and the hollow tubes  14  to reduce friction. 
   The pipe holder  110  is fixed on the base  11 . The pipe holder  110  is configured to hold the pipes  111  in position. When air is pumped into the cavities  142  of the hollow tubes  14 , an air current inside the cavities  142  creates a pushing force that pushes the hollow tube  14  away from the pipes  111 , thereby driving the tip extension  16  away from the second tube frame  17 . The air pumped into the cavities  142  of the hollow tubes  14  and the tube chutes  13  may also be any suitable kinds of gas such as oxygen, nitrogen, etc. 
   The tip extension  16  is needle-shaped, and has a contact tip (not labeled) that touches a surface of an object when the contour measuring probe  10  is used to measuring the object. The tip extension  16  is fixed on the first tube frame  15  so that the tip extension  16  is linearly movable together with the movable rack. The linear measuring scale  18  is fixed on the second tube frame  17  such that it moves (displaces) linearly when the movable rack moves. The displacement sensor  19  is mounted on the base  11  corresponding to the linear measuring scale  18 . The displacement sensor  19  is used for reading displacement values of the linear measuring scale  18 . Alternatively, the positions of the linear measuring scale  18  and the displacement sensor  19  may be exchanged. 
   Again referring to  FIG. 2 , the contour measuring probe  10  further includes a cover  112  that engages with the base  11  and completely seals other various components of the contour measuring probe  10  except the base  11  and a part of the tip extension  16 . The cover  112  defines an opening (not labeled) for allowing an end portion including the contact tip of the tip extension  16  to extend out from the opening. The air is pumped into the gaps between the tube guide  12  and the hollow tubes  14  to form the air bearing via a plurality of tubes  114  mounted to the cover  112 . 
   The contour measuring probe  10  further includes an air discharge system  115 . The air discharge system  115  is configured to eject air out of the cavity  142  of each hollow tube  14 . The air discharge system  115  can be selected from one or more of a group of a first air eject hole (not shown) defined in a center of the cylinder base  140  of each hollow tube  14 ; a second air eject hole (not shown) defined in the cylinder base  140  of each hollow tube  14  and a plurality of peripheral air eject holes (not shown) defined in the cylinder base  140  and surrounding the second air eject hole; a plurality of third air eject holes (not shown) defined in the cylinder base  140  of each hollow tube  14 ; a plurality of cylindrical fourth air eject holes (not shown) defined in a sidewall of each hollow tube  14 ; and the gap  118  between each hollow tube  14  and the corresponding pipe  111 . That is, the air discharge system  115  is a channel communicating an outer of the hollow tube  14  and the cavity  142  of the hollow tube  14 . 
   In alternative embodiments, the contour measuring probe  10  can include only one hollow tube  14  or more than two hollow tubes  14 . In such embodiments, there can correspondingly be only one pipe  111  or more than two pipes  111 . The tube guide  12  may define only one tube chute  13  or more than two tube chutes  13  corresponding to the number of the hollow tubes  14 . 
   In use, the contour measuring probe  10  is placed near the object. The pipes  111  and the tubes  114  communicate with an air chamber (not shown), and air is pumped into the cavities  142  of the hollow tubes  14  and the gaps between the tube guide  12  and the hollow tubes  14 . When the contact tip of the tip extension  16  touches the object, the movable rack together with the tip extension  16  stops moving. When the tip extension  16  and correspondingly the linear measuring scale  18  move from one position to another position, the displacement sensor  19  detects and reads a displacement of the linear measuring scale  18 . That is, a displacement of the tip extension  16  is measured. The displacement sensor  19  connected to the processor  119  sends the displacement of the tip extension  16  to the processor  119 . 
   When manufacturing precision components such as optical lenses, the optical lenses generally need to be re-machined if they do not have desired shape and size. Referring to  FIG. 3 , the contour measuring probe  10  is applied in an ultraprecise equipment A for manufacturing optical lenses. The optical lenses are measured on the ultraprecise equipment A immediately after being machined. Therefore, error caused by releasing the optical lenses from a machining equipment and reclamping the optical lenses on a measuring machine no longer exists. In addition, much time can be saved. The contour measuring probe  10  is mounted on a slidable platform of the ultraprecise equipment A. The ultraprecise equipment A includes a master actuator that moves the contour measuring probe  10  and the slidable platform in at least one direction. The processor  119  is further connected to the master actuator of the ultraprecise equipment A to record a displacement of the slidable platform. 
   When air is pumped into the cavities  142  of the hollow tubes  14 , air pressure in the cavities  142  pushes air out of the hollow tubes  14  via the air discharge systems  115 . That is, air is continuously pumped into the hollow tubes  14  via the pipes  111  and continuously ejected out of the hollow tubes  14  via the air discharge systems  115 . The air pumped into the hollow tubes  14  creates an air current that pushes the hollow tubes  14  to move in a direction that the hollow tubes  14  move out of the tube guide  12 . The air pressure pushing the hollow tubes  14  is relatively small and steady. That is, an overall measuring force that pushes the tip extension  16  is relatively small and steady. As a result, the tip extension  16  of the contour measuring probe  10  is pushed so that the contact tip  162  gently touches the object. Thus, the contact tip of the tip extension  16  and the object are not easily deformed or damaged, thereby improving a precision of measurement. In addition, a pressure inside the cover  112  is kept higher than that of the environment outside the cover  112 , because air ejecting out of the air bearings and the hollow tubes  14  fills the cover  112 . Thus, dust and other particles are prevented from entering the cover  112  through any openings thereof. 
   Referring to  FIG. 4  and  FIG. 5 , the contour measuring method is detailed described as follows when the tip extension  16  of the contour measuring probe  10  moves relative an XZ plane of Y=Y 0 . 
   (1) The contour measuring probe  10  is first driven to move parallel the XZ plane to a first predetermined point. At the same time, the tip extension  16  is pushed out of the  20  against, a surface of the object, and moved along (in contact) the surface of the object to a predetermined point. At the first predetermined point, the processor  119  records a coordinate of the first predetermined point such as (0, Y 0 , 0).
 
(2) The contour measuring probe  10  is then driven to move to a second predetermined point, while the tip extension  16  remains pushing against the surface. At the second predetermined point, and the second point such as (X m1 , Y 0 , Z m1 ) is sensed by the displacement sensor  19  and recorded in the processor  119 .
 
(3) The  20  is sequentially moved to a series of predetermined point, thus the processor  119  will obtain a series of successive point coordinates of (X m2 , Y 0 , Z m2 ), (X m3 , Y 0 , Z m3 ), (X m4 , Y 0 , Z m4 ) . . . (X mi , Y 0 , Z mi ).
 
(4) The processor  119  calculates a series of ideal coordinates according to a function Z=f(X, Y) of an aspect of an ideal object. That is, the processor  119  calculates a series of ideal coordinates of points of a surface of the ideal object as (X m1 , Y 0 , Z n1 ), (X m2 , Y 0 , Z n2 ), (X m3 , Y 0 , Z n3 ), (X m4 , Y 0 , Z n4 ) . . . (X mi , Y 0 , Z ni ).
 
(5) The processor  119  compares the measured coordinates with the ideal coordinates to gain a difference between a real aspect (Here, the measured aspect is regarded as the real aspect) and the ideal aspect of the object. Thus, a series of difference values along the Z-axis between the measured coordinates with the ideal coordinates are gained as ΔZ 1 =Z m1 −Z n1 , ΔZ 2 =Z m2 −Z n2 , ΔZ 3 =Z m3 −Z n3  . . . ΔZ i =Z mi −Z ni .
 
(6) The tip extension  16  is driven to move to other XZ planes of Y=Y 1 , Y=Y 2 , Y=Y 3  . . . Y=Y i  and the steps of (1)-(5) are repeated.
 
(7) The processor  119  contains a compensative software and a machining software therein. A path of a tool of the machining equipment of the ultraprecise equipment A is controlled by the machining software. When the object is machined and measured on the same ultraprecise equipment A, the processor  119  runs the compensative software to modify machining parameters in the machining software according to the difference values along the Z-axis ΔZ i  after measuring and before further machining.
 
   Alternatively, the tip extension  16  can be driven to move in a space of XYZ. Similarly, a series of values ΔZ i  of difference along the Z-axis between the measured coordinates with the ideal coordinates can be gained. Alternatively, the tip extension  16  may be fixed, while the object is driven to move. 
   The contour measuring method can also use other measuring devices, for example, referring to  FIG. 6  and  FIG. 7 , a contour measuring probe  20  in accordance with a second embodiment described as follows. 
   The contour measuring probe  20  is similar to the contour measuring probe  10  except that the contour measuring probe  20  does not include the pipes  111  (shown in  FIG. 2 ) and includes a plurality of tubes  204 ,  206  obliquely disposed in a tube guide  22  relative to hollow tubes  26 . The contour measuring probe  20  includes the tube guide  22 , two hollow tubes  26  and a tip extension  30 . The tubes  204  are oblique relative to an axis of the hollow tubes  26 . That is, an angle defined by extension directions of the tubes  204  relative to the axis of the hollow tubes  26  is in a range from larger than 0° and smaller than 90°. The tubes  204 ,  206  are respectively parallel to and spaced from each other, and are communicated with tube chutes  24  defined in the tube guide  22 . The tubes  206  are symmetrical to the tubes  204  relative to the axis of the hollow tubes  26 , and the tubes  204 ,  206  are disposed in a same plane. Also, the tubes  206  may be not symmetrical to the tubes  204 , but stagger with the tubes  204  so long as a force performed on the hollow tubes  26  at all directions except a moving direction of the tip extension  30  is balance. Alternatively, the tubes  206  can be omitted. With the condition, the hollow tubes  26  may offset under a force performed thereon in a direction perpendicular to the axis of the hollow tubes  26 . 
   Referring to  FIG. 8 , when air is pumped into the tube chutes  24  and forces on a sidewall of the hollow tubes  26  via the tubes  204 ,  206 , air from the tubes  204  performs a force F 1  and air from the tubes  206  performs a force F 2  on the hollow tubes  26 . A value of the force F 1  is the same as that of the force F 2  because the number of the tubes  204  is same as that of the tubes  206  and the tubes  206  and the tubes  204  are symmetrically disposed. Therefore, a force performed on the hollow tubes  26  in an X-direction shown in  FIG. 8  is F 1X +F 2X , and a force performed on the hollow tubes  26  in a Y-direction is 0. The force F 1X +F 2X  pushes the hollow tubes  26  together with the tip extension  30  to move. In addition, an air bearing is formed when air is filled in a gap between the tube guide  22  and the hollow tubes  26 . Therefore, a friction between the tube guide  22  and the hollow tubes  26  is significantly small. 
   Referring to  FIG. 10 , a contour measuring probe  40  in accordance with a third embodiment described as follows may also be used in the contour measuring method. 
   The contour measuring probe  40  is similar to the contour measuring probe  10  except that the contour measuring probe  40  is a vertical type measuring device which using a gravity of a movable rack including a tube guide  42 , two hollow tubes  46 , a first frame  48 , a second frame  52 , and a tip extension  50  as a measuring force. The contour measuring probe  40  does not include the pipes  111  (shown in  FIG. 2 ), while includes an elastic member  58  to support the movable rack. The contour measuring probe  40  includes a base  41 , the tube guide  42 , the hollow tubes  46 , the first frame  48 , the second frame  52 , the tip extension  50 , a linear measuring scale  54 , a displacement sensor  56 , a cover  402 , and the elastic member  58 . The elastic member  58  is a screwed, columned spring. An extension direction of the elastic member  58  is parallel to a direction of gravity and the elastic member  58  is compressed. Therefore, a part of the gravity is balanced by an elastic force of the elastic member  58 . Thus, a measuring force of the tip extension  50  is reduced so that the contact tip of the tip extension  50  and the object are not easily deformed or damaged, thereby improving a precision of measurement. 
   Referring to  FIG. 10 , a contour measuring probe  60  in accordance with a fourth embodiment described as follows may also be used in the contour measuring method. 
   The contour measuring probe  60  is similar to the contour measuring probe  40  except that the contour measuring probe  60  does not include the elastic member  58  and further includes two pipes  662  for allowing air to be pumped into a cavity of each of two hollow tubes  66 . The hollow tubes  662  are disposed at a bottom end of the hollow tubes  66 . A flowing direction of air pumped into the hollow tubes  66  is contrary to a direction of gravity. Therefore, a part of the gravity is balanced by a pushing force of air. 
   Referring to  FIG. 11 , a contour measuring probe  70  in accordance with a fifth embodiment described as follows may also be used in the contour measuring method. 
   The contour measuring probe  70  is similar in principle to the contour measuring probe  10  except that tube guides  72 A,  72 B for holding hollow tubes  74 A,  74 B are offset from each other in the contour measuring probe  70 . That is, the tube guide  72 A is set at a front portion of the base  71 , and the tube guide  72 B is set at a back portion of the base  71 . Because the tube guides  72 A,  72 B are offset from each other, the tube guides  72 A,  72 B in combination hold the hollow tubes  74 A,  74 B along a greater length as measured along a direction coinciding with an axis of movement of the tip extension (not labeled), compared with a corresponding length along which the tube guide  12  holds the tip extension  16  in the contour measuring probe  10 . Thereby, the tip extension of the contour measuring probe  70  can move very steadily forward and backward with little or no lateral displacement. Alternatively, the contour measuring probe  70  can includes one pipe  711  only. Accordingly, air is pumped into one of the hollow tubes  74 A,  74 B. Thereby, the contour measuring probe  70  is further simplified. 
   Similarly, the hollow tubes  24 ,  44 ,  64  of the contour measuring probe  20 ,  40 ,  60  may also be offset from each other as the hollow tubes  72 A,  72 B in the contour measuring probe  70 . 
   It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.