Compact video inspection apparatus with Y, Z, X compounded measurement axes

BACKGROUND OF THE INVENTION

This invention relates to video inspection apparatus having an optical system carriage movable adjustably along X (horizontal) and Z (vertical) axes above a transparent object stage or work table, which is movable along a Y (horizontal) axis disposed at right angles to the X and Z axes, and beneath which table a substage collimator system is adjustable along another X axis simultaneously with the X axis adjustment of the optical system carriage.

Heretofore, typical video inspection systems of the type described have employed an object stage or work table mounted on a base for adjustment along respective X and Y axes which extend at right angles to each other, and generally beneath a downward viewing optical system carried by a slide that is mounted for vertical adjustment on a Z axis. In addition to such typical systems, systems capable of conducting substantially larger measurements are often formed as part of a gantry arrangement which supports the optical system and its vertically movable slide. Typically in such system a large bridge structure is supported on two large linear bearings which support the bridge for motion solely in a Y direction relative to a stationary object. Upon the bridge is mounted a linear slide which is adjustable on the bridge in an X direction, and which carries for vertical adjustment thereon the optical system slide. In this manner the optical system can be positioned over a desired X, Y location.

Among the advantages of the present invention over such prior art systems is the fact that the measurement range in the vertical Z direction can be extended substantially, while offering certain precision advantages. For example, having the X axis in a fixed relationship to the measurement plane of the optical system at any height Z within the measurement volume, provides better consistency and reduces the inaccuracy effects of pitch, roll, and yaw of the associated linear slide mechanisms.

Accordingly, it is an object of this invention to provide an improved, compact video inspection apparatus of the type described which utilizes an object stage or work support that moves on a linear slide only in one direction (the Y direction), while the slide or carriage which is mounted for movement in the X direction, and which supports thereon the optical system, is movable vertically in the Z direction simultaneously with the entire optical system.

A further object of this invention is to provide an improved video inspection system of the type described in which the object stage or work support is mounted on a base for movement only in one direction (the Y direction), while a yoke mechanism, which is mounted for vertical movement on the base relative to the work support, has mounted thereon a slide or carriage which is movable in an X direction on the yoke, and which carries an associated optical system that is mounted for movement with the carriage in the X and Z directions relative to the work support.

Still another object of this invention is to provide an improved, compact video inspection apparatus of the type described wherein a substage collimator is mounted beneath the transparent work support or object stage for adjustment with the optical system in the X direction, thereby to maintain the collimator in registration with the optics head of the optical system.

Another advantage of this invention is that it includes an optical system carriage that is adjustable horizontally in an X direction on a yoke that in turn is adjustable vertically in a Z direction, thereby to achieve precise Z motion for the optical system.

Still a further object of this invention is to provide an inspection apparatus of the type described in which an optical system carriage, which in the X direction, is connected by a cable to a substage collimator to transmit movement of the optical system carriage to the substage collimator.

SUMMARY OF THE INVENTION

A transparent work-supporting slide is mounted on a base for adjustment horiziontally thereon in a Y direction. A yoke is supported for vertical movement in a Z direction on a pair of cylindrical columns which project upwardly from the upper surface of the base. A carriage which is mounted on the face of the yoke for horizontal adjustment in an X direction carries a lens system having in its lower end an objective lens mechanism which faces the transparent work support, and which has in its upper end a video camera for receiving an image from the objective lens mechanism. A substage collimator supporting arm is mounted in the base beneath the transparent work support for horizontal adjustment in the X direction. The forward end of the arm extends beneath the transparent work support and has therein a source of collimated light, which registers with the objective lens mechanism and is disposed to illuminate the underside of a workpiece mounted on the transparent work support. A system of cables connects the optical system carriage to the substage collimator arm so that the carriage and arm are made to shift in unison in the X direction, thereby maintaining the collimated light source always in registry with the objective lens of the optical system.

THE DRAWINGS

FIG. 1

is a perspective view of a compact video inspection apparatus made according to one embodiment of this invention, and illustrating schematically by the intersecting lines X, Y and Z, the respectively different directions in which the three different components of the apparatus are adjustable;

FIG. 2

is a front elevational view of this apparatus, but with a portion thereof shown in section;

FIG. 3

is a rear elevation viw of this apparatus on a slightly smaller scale, and illustrating one manner in which the substage collimator component of the apparatus may be connected by a cabling mechanism to a counter-balancing carriage which is mounted with a lens system carriage for adjustment in the Z direction by a vertically adjustable yoke, and for adjustment in an X direction relative to the yoke.; and

FIG. 4

is a rear elevational view similar to

FIG. 3

, but showing a modified form of the cabling mechanism shown in FIG.

3

.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings by numerals of reference,

10

denotes generally the base of compact video inspection apparatus made according to one embodiment of this invention. The base

10

, which is generally rectangular in configuration has a plane front surface

11

, and a plane upper surface

12

extending normal to the front surface

11

. Upper surface

12

has formed centrally thereof a relatively deep, rectangularly shaped recess

13

which extends between the front and rear ends of the base

10

, and which has opposed, spaced, parallel side walls

14

and

15

. Mounted in recess

13

for adjustment longitudinally thereof in the direction Y, as shown in

FIG. 1

, is a rectangularly shaped work supporting table

16

. As shown more clearly in

FIG. 2

, opposite sides of the table

16

are supported by two linear sets of ball bearings

17

in the confronting side walls

14

and

15

of the recess

13

. Like base

10

, table

16

has in the upper surface thereof a large rectangular recess

18

(

FIG. 2

) the upper end of which is closed by a transparent, rectangular, work supporting plate

19

that is secured around its edges in registering recesses formed in the inside surfaces of recess

18

.

Secured at their lower ends in the base

10

adjacent the rear end thereof, and projecting vertically upwardly from the upper surface

12

of the base in spaced, parallel relation to each other are two cylindrical rod bearings

21

. Mounted adjacent opposite ends thereof on the bearings

21

for vertical adjustment thereon by a pair of conventional drive screws

22

in the Z direction, as shown in

FIG. 1

, is a rigid yoke

24

which is generally rectangular in cross section. Screws

22

, which are connected at their lower ends to the shafts of a pair of motors

23

(

FIG. 2

) that are mounted in base

10

adjacent opposite sides thereof, are drivingly connected to internally threaded bores formed in yoke

24

adjacent opposite sides thereof, Motors

23

, which may be controlled by any conventional means forming no part of this invention operate in unison to shift yoke

24

selectively in opposite directions in the Z axis.

In its front face or surface, the surface facing the forward end of base

10

, the yoke

24

has therein an elongate, rectangular recess

25

, which extends between opposite sides of the yoke, and which has slidably mounted therein a rectangularly shaped slide or carrier

26

, which is supported on yoke

24

for sliding movement relative thereto in the X direction. Secured to the face of the carrier

26

for movement therewith in the X direction is a housing

27

for a conventional optical magnification system. Mounted on the upper end of housing

27

for movement therewith is a conventional video camera

28

, which is disposed to receive from the optical system images of the workpiece (not illustrated) mounted on the transparent plate

19

. To this end a fitting

29

which projects from the lower end of housing

27

has therein the usual objective lens mechanism that is disposed to be placed in registry with a workpiece that is mounted on plate

19

for inspection by the optical system and for recording by the camera

28

.

Carriage

26

has therethrough an elongate bore

31

which extends in the X direction between opposite ends of the carriage. Secured in a recess in carriage

26

intermediate the ends thereof is a drive nut

32

having an internally threaded bore disposed coaxially of the carriage bore

31

. A carriage drive screw

33

, which extends coaxially and rotatably through carriage bore

31

, is drivingly threaded intermediate its end with the bore in drive nut

32

. Screw

33

is connected at one end to the output shaft of a motor

34

which is secured to the bottom of the recess

25

in yoke

24

adjacent one end thereof, and is rotatably journaled at its opposite end in a bearing

35

which also is secured in recess

25

adjacent the opposite end thereof. When motor

34

is energized the screw

33

drives carriage

24

selectively in opposite directions in recess

25

, and always in the X direction. Concurrent with such movement, the housing

27

and its associated video camera

28

and lens fitting

29

likewise are moved as a unit in the X direction with the carriage

26

.

To determine the exact position of the carriage

26

and associated optical system housing

27

conventional location sensing devices may be employed. In the embodiment illustrated, carriage

26

has mounted in a recess therein an electrical position sensor

37

, which registers with an elongate scale

38

that is mounted in the bottom of the recess

25

to extend longitudinally thereof in the X direction. In a similar manner, each vertical rod

21

and

22

has mounted thereon an elongate scale

41

which registers with one of two electrical sensors

42

that are mounted in the yoke

24

adjacent opposite ends thereof to provide precise indications of the position of yoke

24

in the Z direction relative to the work supporting chamber. And as shown in

FIG. 1

, flanged sections of the table

16

, at opposite sides thereof slidably overlie the upper surface

12

of base

10

and carry electrical sensors

44

, which register with and are slidable over the upper surfaces of elongate, linear scales

45

, which are secured in the upper surface

12

of the base

10

adjacent opposite sides of the recess

13

. In this manner the respective positions of the carrier

26

in the X direction, the table

26

in the Y direction, and the yoke

24

in the Z direction can be accurately determined by the signals produced by the sensors

37

,

42

and

44

.

Mounted in the recess

13

of base

10

for movement in the X direction beneath the work supporting plate

19

is an elongate collimator supporting arm

53

. Arm

53

, which is generally rectangular in cross section, is slidably supported adjacent its rear or left end as shown in

FIG. 1

on a pair of spaced, parallel, cylindrical guide rods

51

and

52

, which are secured at opposite ends thereof in the opposed side walls

14

and

15

of a recess

13

in the base

10

. The rods

51

and

52

, which extend parallel to each Other in the X direction, extend slidably intermediate their ends through a pair of registering recesses formed in arm

53

to extend parallel to each other between opposite sides of the arm. Arm

53

is thus slidable in the X direction on the rods

51

and

52

, and in a plane which is spaced beneath and parallel to the transparent work supporting plate

19

.

On its forward end arm

53

has in the upper surface thereof an opening

54

which, as noted hereinafter, is positioned to register with the objective lens mechanism carried by the fitting

29

on the lower end of the video camera housing

27

. Mounted in arm

53

beneath the opening

54

is a conventional light source which is operable on a conventional manner to transmit collimated light upwardly through opening

54

and against the bottom of any work which happens to be mounted thereover on the transparent plate

19

.

In order to maintain the light emitting end of the arm

53

in registry with the video camera housing

27

it is necessary that the video camera carrier

26

move in unison in the X direction. For this purpose the rear face of

25

has therein an elongate slot

56

in which is slidably mounted a rear Of counterbalancing carriage

57

which is slidable in the X direction between opposite ends of the yoke

24

. For this purpose the carriage

26

is secured at one end thereof (the left end in FIG.

1

and the right end in

FIG. 3

) to One end of a cable

61

, the opposite end of which cable is secured to one end (the left end in FIG.

1

and the right end in

FIG. 3

) of the rear carriage

57

. Intermediate its ends cable

61

passes around two, spaced, circular pulleys

62

and

63

which are mounted to rotate in a common plane about spaced, vertical axes which are located adjacent the left ends of the recesses

25

and

56

in yoke

24

, as shown in FIG.

1

. At its opposite end, or at the right end in FIG.

1

and the left end in

FIG. 3

, the front carriage

26

is secured to one end of another cable

65

, the opposite end of which is connected to the rear carriage

57

at the end thereof remote from the end to which the cable

61

is attached—i.e., the right end of carriage

57

as shown in

FIG. 1

, and the left end thereof as illustrated in FIG.

3

. Intermediate its ends cable

65

, like the cable

61

, is guided around two, spaced pulleys

66

and

67

which are mounted on yoke

24

adjacent the right ends in

FIG. 1

of the recesses

25

and

56

to rotate in a common horizontal plane.

In addition to being connected to the front carriage

26

, and referring now to

FIG. 3

, the rear carriage

57

has rotatably mounted on the rear face thereof a spool

71

which rotates about a Y axis, and which has associated therewith, in a conventional manner, a recoil spring the purpose of which will be noted hereinafter. The spool

71

is connected to the collimator arm

53

by another cable

72

which is wound intermediate its ends around the spool

71

and extends at opposite ends thereof, and in opposite directions from diametrally opposite sides of the spool, around a pair of pulleys

73

and

74

, respectively, which are mounted in the recess

56

of the yoke

24

to rotate about spaced, parallel Y axes. From the pulley

73

one end of the cable

72

extends vertically downwardly where it passes around another pulley

75

, which is mounted in base

10

, and then travels horizontally to a point where it is attached to one side of arm

53

between the guide rods

51

and

52

. The other end of cable

72

, after passing around pulley

74

, passes vertically downwardly and around another pulley

76

which is mounted to rotate in the base

10

adjacent the side thereof remote from the side containing pulley

75

. After passing around pulley

76

the associated end of cable

72

is attached to the side Of arm

53

opposite to and in registry with the point to which the opposite end of the cable has been attached.

As a result of the above-noted cable connections, whenever the front carriage

26

is shifted in an X direction, for example toward the right in

FIG. 3

, cable

61

causes the rear carriage

57

to be shifted toward the left in FIG.

3

. The spool

71

is held against rotation by its associated recoil spring, so that as carriage

57

moves toward the left in

FIG. 3

, the section of cable

72

that passes around pulleys

73

and

75

cause arm

53

likewise to be drawn toward the right in

FIG. 3

, thereby maintaining the light source in arm

53

in vertical registry with the lens mechanism in fitting

29

. Of course when the front carriage

26

is moved toward the left in

FIG. 3

, carriage

57

will move in the Opposite direction and cable

72

, via pulleys

74

and

76

, will move arm

53

also to move toward the left in FIG.

3

.

FIG. 4

, which is a rear view generally similar to

FIG. 3

, illustrates a modified form of the invention in which the rear carriage

57

is secured to the front carriage

26

for movement therewith in the X direction by means of a rigid bar or bracket

81

. At one end bar

81

is fixed to the back of the carriage

26

, and extends rearwardly therefrom through an elongate slot

82

formed in the yoke

24

, and is fixed at its opposite end against the rear surface of yoke

57

. As shown in

FIG. 4

, bracket

81

thus secures carriages

26

and

57

in registry with each other, and is slidable longitudinally in the slot

82

which extends in the X direction in the yoke

24

intermediate the ends thereof. As in the preceeding embodiment, the circular, spring-loaded spool

71

is mounted to rotate about a Y axis on the rear face of the carriage

57

. Also as in the preceding embodiment, a cable

71

is wound intermediate its ends around the spool

71

, and has opposite ends thereof extending in opposite directions from diametrally opposite sides of the spool.

In this embodiment opposite ends of cable

72

extend around a first pair of spaced reversing pulleys

83

and

84

, which are mounted in recess

56

to rotate about Y axes spaced from opposite ends of the carriage

57

. From the pulley

83

the associated end of cable

72

extends horizontally in an X direction toward the opposite end of recess

56

where is passes over another pulley

85

that is rotatably mounted in recess

56

coaxially of a Y axis. From pulley

85

the cable

72

passes vertically downwardly and around another Y-axis mounted pulley

86

which is rotatably mounted in base

10

, after which the cable passes in an X direction into the recess

13

where its terminal end is secured to one side of arm

53

. The other end of the cable

72

, after passing around the reversing pulley

84

extends in the X direction toward the opposite end of recess

56

where it passes around another Y-axis mounted pulley

87

, and then vertically downwardly to a sixth pulley

88

, which is mounted in base

10

to rotate about a Y axis. From the pulley

88

the associated end of cable

72

passes in the X direction into recess

13

where it is secured to the side of arm

53

opposite to and in registry with the other end of the cable.

With this construction, when the front and rear carriages

26

and

57

move in unison towards, for example, the left in

FIG. 4

the reversing pulley

84

provides slack for the associated end Of cable

72

, while the reversing pulley

83

causes the associated end of cable

72

to be drawn in the same direction as the carriages

26

and

57

, thereby causing the light emitting end of the arm

53

to remain in registry with the lens fitting

29

. This construction eliminates the need for employing the cables

61

and

65

described in connection with the preceding embodiment. Moreover, in connection with both embodiments, whenever the yoke

24

is shifted vertically on the columns

21

, the spring-loaded spool

71

permits extension of the overall operating length of the cable

72

when the yoke is elevated, and conversely, when the yoke

24

shifts downwardly on the columns

21

, the recoil spring associated with spool

71

causes the spool to rotate in a direction (for example counterclockwise in

FIGS. 3 and 4

) to maintain proper tension in the cable

72

at all times.

From the foregoing it will be apparent that the present invention provides an extremely accurate and compact inspection apparatus which utilizes in arm

53

a substage illuminator that always remains in registry with the objective lens mechanism in the fitting

21

regardless Of the adjustment of the associated video camera

28

in the X or Z direction, and regardless also of the movement of the associated work that is being inspected on movement Of the table

16

and its transparent work support

19

in the Y direction. Moreover, the electrical position sensors

37

,

42

and

44

in association with their related scales, provide instantaneous and very accurate indications of the respective positions of the components that are adjusted in the X, Z and Y directions, respectively.

While this invention has been illustrated and described in detail in connection with only certain embodiments thereof, it will be apparent that it is capable Of still further modification. For example, a conventional touch probe could be mounted on yoke

24

adjacent to, or in place of the video optical system, and for adjustment also in the X direction on the yoke. Also, of course, two separate cables could be wound on spool

71

, or on two such spools, to perform the same function as cable

72

. Moreover, it will be apparent also that this application is intended to cover any such modifications as may fall within the scope of one skilled in the art, or the appended claims.