Abstract:
The present invention is a touch probe which can be connected to a computer controlled machine for determining positions of and defining shapes of work pieces, edges, hole centers and contours. The probe due to it design allows for a simpler and effective alternative to previous probes. The probe includes a body, stylus, a shank and an internal assembly. The body contains the internal assembly, which provide signals to a computer. The arrangement of the internal assembly is what makes the present invention simpler to manufacture and allow the probe to be miniaturized. The internal assembly includes an upper circuit board with a Light Emitting Diode (LED), a spring, a spring cap, a stylus mount, a housing, carbide balls, a lower circuit board, a support ring and wires.

Description:
This application claims the benefit of U.S. Provisional Application Nos.: 60/124,391 filed Mar. 15, 1999, No. 60/131,478 filed Apr. 29, 1999, and No. 60/142,333 filed Jul. 3, 1999, and are hereby incorporated by reference. 
    
    
     BACKGROUND 
     Touch probes are devices known for uses such as measuring objects, determining positions of and defining shapes of work pieces, edges, hole centers and contours. There are many types of these devices available on the market. But, these devices can have complicated internal workings, which increase manufacturing costs and limit miniaturization of the device. With the increase capabilities in computers and software it is possible to transfer some of the complicated features away from the probe itself. 
     It is an object of the present invention to provide a touch probe which can be made smaller, which simplifies manufacture and which reduces the cost to manufacture. 
     SUMMARY OF THE INVENTION 
     The present invention is a touch probe which can be connected to a computer controlled machine for determining positions of and defining shapes of work pieces, edges, hole centers and contours. The probe due to it design allows for a simpler and effective alternative to previous probes. The probe includes a body, stylus, a shank and an internal assembly. The body contains the internal assembly, which provide signals to a computer. The arrangement of the internal assembly is what makes the present invention simpler to manufacture and allow the probe to be miniaturized. The internal assembly includes an upper circuit board with a Light Emitting Diode (LED), a spring, a spring cap, a stylus mount, a housing, carbide balls, a lower circuit board, a support ring and wires. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a probe connected to a machine according to the present invention; 
     FIG. 2 is an exploded view of the probe according to the present invention; 
     FIG. 3 is a side view of the probe according to the present invention; 
     FIG. 4 is a cross-sectional side view of the probe according to the present invention; 
     FIG. 5 is a top perspective view of a stylus mount according to the present invention; 
     FIG. 6 is a bottom perspective view of a stylus mount according to the present invention; 
     FIG. 7 is a side view of a stylus and stylus mount according to the present invention; 
     FIG. 8 is a top perspective view of a housing according to the present invention; 
     FIG. 9 is a bottom perspective view of a housing according to the present invention; 
     FIG. 10 is a top perspective view of a housing and spring cap according to the present invention; 
     FIG. 11 is a bottom perspective view of a housing and spring cap according to the present invention; 
     FIG. 12 is a top perspective view of a lower circuit board according to the present invention; 
     FIG. 13 is a cross-sectional side view of a bottom of the probe according to the present invention; 
     FIG. 14 is a cross-sectional side view of a bottom of the probe according to the present invention; 
     FIG. 15 is a schematic of the wiring of the probe according to the present invention; 
     FIG. 16 is a schematic of the wiring of the probe according to the present invention; and 
     FIG. 17 is a schematic of the electronics of the probe according to the present invention. 
    
    
     DETAILED DESCRIPTION 
     The present invention is a touch probe  10  which can be connected to a computer controlled machine  12  for determining positions of and defining shapes of work pieces, edges, hole centers and contours. The probe  10  includes a body  14 , stylus  16 , a shank  18  and an internal assembly  20 , as shown in FIGS. 1-4. The body  14  contains the internal assembly  20 , which provide signals to the computer for defining an object  24 . The stylus  16  is a shaft with a round tip  22  that actually contacts the object  24  to be defined, as shown in FIGS. 1 and 7. The shank  18  extends upward from the body  14  and is inserted into a chuck  26  of the machine  12 , whereby the machine  12  moves the probe  10  about the object  24  to be defined. 
     The body  14  is an open ended cylinder  28  with an end cap  30 . The cylinder  28  includes a top  32  and bottom  34 . The bottom  34  of the cylinder  28  includes threading  36  slightly recessed from an outside surface  38  of the cylinder  28 . The end cap  30  includes an open ended top  40  having internal threading  42  and includes a closed bottom  44  having a stylus hole  46  to receive the stylus  16 . The end cap  30  screws onto the bottom  34  of the cylinder  28 . The stylus hole  46  includes a ridge  48  extending around it and extending outward from the end cap  30  to receive a molded rubber boot  50  to seal the stylus hole  46 . The boot  50  includes a hole  52  which seals around the stylus  16  as it projects from the bottom  44  of the end cap  30 . The cylinder  28  also includes three threaded set screw holes  54  near the top  32  of the cylinder  28 , a lens hole  56  and a connector hole  58  to receive a connector receptacle  60 . The connector receptacle  60  is wired to the internal assembly  20  and allows connection of a cable from the computer. 
     The shank  18  includes a machine attachment end  62 , a reverse tapered boss  64  and a top cap between the attachment end and the boss  64 . The boss  64  is inserted into the top of the cylinder  28 , whereby the top cap  66  seals the top  32  of the cylinder  28 . The shank  18  is secured to the body  14  using conical set screws  68 . Whereby, the set screws  68  are threaded through the set screw holes  54 , into the cylinder  28  and against the boss  64 . The use of conical set screws  68  and the reversed tapered boss  64  allows for the quick and easy adjustment of the probe  10  concentricity with the machine  12  to which the probe  10  is installed. A clear snap-in lens  70  is shown to be snapped into the lens hole  56 . 
     The internal assembly  20  includes an upper circuit board  72  with a Light Emitting Diode (LED)  74 , a spring  76 , a spring cap  78 , a stylus mount  80 , a housing  82 , carbide balls  84 , a lower circuit board  86 , a support ring  88  and wires  90 . The upper circuit board  72  is secured with screws to a top of the spring cap  78 . The upper circuit board  72  is wired to the connector receptacle  60  and contains solid state electronics for collecting and transmitting the signals to the computer connected to the probe  10 . The stylus mount  80  includes a top  96  and a bottom  98 , as shown in FIGS. 5-6. The bottom  98  of the stylus mount  80  is internally threaded to receive a threaded top  100  of the stylus  16 . The top  96  of the stylus mount  80  includes three equally spaced steel pins  102  extending outward from the top  96 . The top  96  of the stylus mount  80  also includes a set screw hole  104  and a set screw  106 . The set screw  106  is electrically connected to the pins  102  via the stylus mount  80  when in the set screw hole  104  and is use to secure a ground wire to the stylus mount  80 . The housing  82  has a top  108 , a bottom  110  and a continuous side  112 , as shown in FIGS. 2,  8 - 11 . The bottom of the housing  82  includes six ball holes  114  around its periphery and a center hole  116 . The ball holes  114  are configured such that a portion of each ball  84  extends into the housing  82  from the bottom  110  of the housing  82 , but each ball  84  is restrained from fully entering the housing  82 . The ball holes  114  are also configured so that there are three sets of paired balls  84 , whereby the three sets are equally space apart similar to the three pins  102 . The balls holes of each set are close together to allow the each of the paired balls  84  to support one each of the three pins  102  of the stylus mount  80  between the paired balls  84 . The housing  82  is shown with three slots  118  in the side  112  of the housing  82  to receive and guide the pins  102 . When in place, the stylus mount  80  is inserted into the housing  82  from the top  108  of the housing  82 , such that the bottom  98  of the stylus mount  80  projects through the center hole  116  of the housing  82  and the pins  102  are in the slots  118  and contact the balls  84 . 
     The lower circuit board  86  acts as a lower plate to pressure the balls  84  into the ball holes  114 . The lower circuit board  86  includes a contact pad  120  for each ball  84 , as shown in FIGS. 8,  12 , and  14 . Each contact pad  120  is wired with a wire  90  to the upper circuit board  72 . The lower circuit board  86  is secured to the bottom of the housing  82  using the support ring  88  and screws  122 , as shown in FIGS. 2 and 4. The support ring  88  and the lower circuit board  86  both include screw holes  124  to receive the screws  122 , which are screwed into the housing  82 . The support ring  88  keeps the lower circuit board  86  flat when pressed against the balls  84 . The spring cap  78  and the housing  82  are configured to assemble by snapping together to secure the stylus mount  80  in the housing  82 , as shown in FIGS.  2  and  10 - 11 . The spring cap  78  is shown with a groove  126  and ridge  128  configuration which snaps together with a groove  126  and ridge  128  configuration of the housing  82 . The spring  76  is positioned against and between an inside surface  130  of the spring cap  78  and the pins  102  of stylus mount  80 . Where a bottom end  132  of the spring  76  rests against the pins  102  of the stylus mount  80 . The spring  76  provides a tension force against the three pins  102 , where the pins  102  are pressured against the three sets of paired balls  84 . The housing  82  also includes a lip  134  extending around the bottom  110  of the housing  82 . The internal assembly  20  is inserted into the bottom  34  of the cylinder  28  until the lip  134  of the housing  82  comes against the bottom of the cylinder  28 , as shown in FIG.  13 . The end cap is then threaded onto the bottom of the cylinder  28 , whereby the inside surface  136  of the bottom  44  of the end cap comes against the support ring  88  of the internal assembly  20 . With the end cap on the cylinder  28 , the internal assembly  20  is rigidly secured in the cylinder  28  of the probe  10 . 
     The steel pins  102  attached to the stylus mount  80 , six carbide balls  84  and the lower circuit board  86  make up six precision electrical switches, as shown in FIGS. 4, and  15 - 16 . The six switches are formed by the three pins  102  against the six balls  84 . Where the pins  102  are the ground and the balls  84  are connected to upper circuit board  72  by the contact pads  120  and the wires  90  of the lower circuit board  86 . Each contact pad  120  is wired to a series of diodes on the upper circuit board  72 , as shown in FIG. 4, and  15 - 17 . These diodes act as logic gates. The series of logic gates drive the output signal as well as the LED  74  located on the upper circuit board  72 . There is an input voltage which enters through the connector receptacle  60  and onto the upper circuit board  72  for powering the probe  10 . When all the pins  102  are in contact with all of the balls  84 , the logic gate on the upper circuit board  72  is grounded and switches to a high state, which allows a 4 or more volt output signal from the probe  10  to the computer. When one or more pins  102  breaks contact with one of the balls  84  due to movement of the stylus  16 , the ground is broken. Once the ground is broken, the logic gate on the upper circuit board  72  is ungrounded and switches to a low state, which allows a less than 1 volt output signal from the probe  10  to the computer. FIG. 17 shows a logic diagram for the probe  10 . The computer includes software which knows the position of the probe  10  and the direction the probe  10  is moving. The computer software uses the output signals to record the position of the tip  22  of the stylus  16  when it is deflected. The LED  74  is the color GREEN when the stylus  16  is not deflected and all switches are closed and the LED  74  is the color RED when the stylus  16  is deflected and any of the six switches are open. The LED  74  will remain RED and the output signal will remain below 1 volt while the stylus  16  is deflected. The output signal will be greater than 4 volts and the LED  74  will be green when the stylus  16  is not deflected. The LED  74  is positioned to illuminate the, clear lens  70 , which provides a simple outside status indication of the probe  10  and the stylus  16 . 
     While different embodiments of the invention have been described in detail herein, it will be appreciated by those skilled in the art that various modifications and alternatives to the embodiments could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements are illustrative only and are not limiting as to the scope of the invention which is to be given the full breadth of any and all equivalents thereof.