as illustrated in the drawings , an ophthalmic instrument support apparatus is generally constructed from a container 10 , a support device 12 , and system control 14 . in the preferred embodiment , the ophthalmic instrument is a keratometer or ophthalmometer and container 10 encloses an optical system ( not shown ) capable of measuring the anterior corneal radii of an eye . support device 12 generally provides the support by employing a fixed support apparatus 16 and a movable support apparatus 18 . fixed support apparatus 16 is used to support the ophthalmic instrument in a generally fixed position on a support surface , such as a table . when desired , an enclosure may be used to enclose operating parts of the ophthalmic instrument , as illustrated in fig1 and 3 . movable support apparatus 18 is used to move container 10 in any of one of three dimensions relative to fixed support apparatus 16 , while supporting container 10 . these three dimensions may be described as front to back , side to side and up and down . side to side movement of the container is arcuate about an axis of rotation . however , movement in one dimension may be combined with movement in a second and / or third dimension so as to result in an infinite number of vectors . as best shown in fig1 the arcuate movement of container 10 relative to fixed support 16 is controlled through the interaction between fixed support apparatus 16 and braking device 20 . braking device 20 is attached to movable support 18 and includes a solenoid 22 with a core 24 and a brake friction pad 26 disposed on the core 24 . friction pad 26 is positioned for engagement with a friction surface 28 . friction surface 28 is a part of fixed support 16 and is preferably disposed in an arcuate path about an axis of rotation 30 . the interaction of pad 26 on surface 28 prevents rotational movement of container 10 . the arcuate movement of container 10 is thus permitted by activating and deactivating solenoid 22 . the front to back movement of container 10 relative to fixed support 16 is obtained through the interaction between movable support means 18 and mechanical apparatus 32 . mechanical apparatus 32 uses a friction wheel 34 connected to movable support 18 and fixedly attached to control means 14 . friction wheel 34 is rotatably disposed within a clamp 36 at axis of rotation 38 of wheel 34 . clamp 36 is attached to movable support 18 , while wheel 34 rides on a friction pad 40 . thus , movement of control means 14 causes rotation of friction wheel 34 on friction pad 40 and corresponding movement of movable support 18 either forward or backward as desired . the apparatus used in movable support 18 to move container 10 substantially perpendicular to the fixed support 16 generally includes an electric motor 42 supported within movable support 18 . preferably , electric motor 42 is connected to a gear train 44 for rotating screw mechanism 46 . screw mechanism 46 is externally threaded for mating an internally threaded nut 48 attached to container support 50 fixed to container 10 . raising and lowering movement of container 10 is thus provided by activating and deactivating motor 42 . easy control over the movement of container 10 in the first , second and third dimensions is obtained by using an electro - mechanical control rod 52 . attached to the front portion of control rod 52 is a first electric switch 54 . preferably , switch 54 is a three position switch and is electrically connected to a reversible motor 42 for rotational activation in a first direction , deactivating , and activation in a second opposite direction of motor 42 to raise , stop and lower container 10 relative to fixed support 16 . a second electric switch 56 is connected to the top portion of control rod 52 and is electrically connected to solenoid 22 for activating and deactivating brake 20 to permit path of container 10 in an arcuate movement about axis of rotation 30 of movable support 18 . friction wheel 34 is disposed at the base of control rod 52 and the forward and back rotation of rod 52 about axis of rotation 38 of wheel 34 provides corresponding movement of container 10 in a corresponding direction relative to axis of rotation 30 of movable support 18 . as may be seen in fig1 of the drawings , when control means 14 is rotated either forward or backwards this rotation causes corresponding rotation of friction wheel 34 . since friction wheel 34 rests on friction pad 40 which is attached to lower portion 18b of movable support means 18 , this rotation of friction wheel 34 causes upper portion 18a of movable support means 18 to move in a direction opposite the movement of control means 14 and friction wheel 34 . in order to allow this movement of upper portion 18a of movable support means 18 over the lower portion 18b of movable support 18 , as shown in fig3 of the drawings , upper portion 18a of movable support means 18 rides on a slide 19 which moves back and forth in relation to lower portion 18b . between lower portion 18b and slide 19 , conventional anti - friction devices may be used such as the franke bearings 19a and 19b shown in fig3 . as best shown in fig4 of the drawings , friction surface 28 is a part of fixed support 16 and is disposed in an arcuate path about axis of rotation 30 . the interaction of pad 26 on surface 28 prevents rotational movement of container 10 ( not shown ). the arcuate movement of container 10 is thus permitted by activating and deactivating solenoid 22 . braking device 20 is attached to movable support 18 and includes a solenoid 22 with a core 24 and brake friction pad 26 disposed on core 24 . as shown in fig5 of the drawings , fixed support apparatus 16 is used to support the ophthalmic instrument in a generally fixed position on a support surface , such as a table . movable support apparatus 18 is used to move container 10 in any one of three dimensions relative to fixed support 16 . enclosure 58 is used to enclose operating parts of movable support 18 and fixed support 16 . as shown in fig6 of the drawings control means 14 is fixedly attached to friction wheel 34 . friction wheel 34 is rotatably disposed within clamp 36 . clamp 36 is attached to upper portion 18a of movable support means 18 while wheel 34 rides on friction pad 40 which is connected to lower portion 18b of movable support means 18 . when the control means 14 is moved either forward or back friction wheel 34 rotates correspondingly on friction pad 40 . this causes upper portion 18a of movable support means 18 to move in the opposite direction ; the lower portion 18b of movable support means 18 remains stationary . in order to allow this movement upper portion 18a rides on slide 19 . as shown in fig3 of the drawings , conventional anti - friction devices such as franke bearings 19a and 19b are used to facilitate this sliding motion .
an ophthalmic instrument support which comprises a container for enclosing ophthalmic instrumentation , a fixed support upon which the device rests , a movable support apparatus for moving the container , and a control apparatus for controlling movement of the container . the control apparatus employs a control rod having a switch to activate and deactivate an electric motor which controls the movement of the container in a first dimension as well as allowing manual movement of the container in a second and third dimension relative to the base .