MXPA97002964A - Limiting control for ma lever - Google Patents

Abstract

The present invention relates to an alignment limiting device for ophthalmic instrument, characterized in that it comprises: a test shaft passing through the instrument, a motor drive means for moving said axis vertically, a first switch for activating the means of drive to one direction, a second switch to activate the driving means in the other direction, the manual means for selectively coupling the first or second switches, to provide manual control of the driving means, the optical medium having a field of view and the means for detecting the position of an eye, the optical means includes the signal means for generating a signal having a value representing a vertical location of the eye relative to the axis when the eye is within the field of view, and the comparator means to determine when the Signal means generates the signal and the displacement control of the drive means from the pr and second switches to said signal, whereby the optical medium is in exclusive control of the driving means if the eye is within the field of vision

Description

O? NTROTI TiTMITAnOR FOR PA AMCA Pg M? MTO AMTlSgEDBiaTES Dg IA TNVEMC! T? Tf 1. Field of the Invention The present invention relates to alignment systems for ophthalmic instruments, and more particularly to an automatic alignment control for manual limiting means of an ophthalmic instrument. 2. Description of the Previous Technique Many ophthalmic instruments require the alignment of a test axis with the center of the patient's eye and an element of the instrument must be separated at a chosen distance from the eye. In such instruments, the non-contact tonometer has been used by physicians in their ophthalmic practice for more than 20 years. The first non-contact tonometers, manufactured by the American Optical Corporation, use a joystick, a handle that extends from a mounted sphere to provide rotational movement around the center of the sphere, with REF: 24423 the end to move the instrument in a horizontal plane (XZ). To move the test axis horizontally in the X direction towards the center of the patient's eye, the control lever is tilted in a corresponding direction. To move the element in the Z direction towards or away from the eye, the joystick is tilted in a corresponding direction. Obviously, a compound horizontal movement can be obtained by moving the joystick in a direction between the orthogonal directions mentioned above. Vertical movement on the Y axis in these non-contact tonometers is provided by a separate knob hinged by a threaded shaft mounted for rotation on a carrier and which engages a nut on the support to provide vertical movement of the shaft. proof. The "on" button used to trigger an air discharge to the initial contactless tonometers is located in the center of the knob used to control vertical movement, on the Y axis. The posterior models of the non-contact tonometers produced by Reichert -Jung Ophtalmic Instruments (a successor to the American Optical Corporation) and the To I Optical Company (Topcon) combine the vertical Y axis control and the "on" button on the joystick. An example of this type of joystick is described by Japanese publication number 4-50562. Such controls have several disadvantages as described by the Japanese publication mentioned above. A problem encountered results from the twisting of the wires used to connect the "on" button to the electronic devices of the instrument and the expenses associated with the elimination of the problem of twisted wires. Another disadvantage of rotating the control lever for vertical movement control is that the practitioner can not perform the vertical movement when holding the control lever in the conventional manner because of the movement. Vertical frequently requires one or more revolutions of the joystick in order to vertically place the test axis in the center of the eye. In addition, many doctors find it difficult to maintain the horizontal position while adjusting the vertical position of the instrument. A system for determining the position of a test axis in relation to the center of the eye, as well as the distance from an element from the eye, is described in commonly assigned U.S. Patent No. 4,881,807. This patent discloses an optical alignment system having a camera means and a visual display to indicate the relative position of the test axis when the eye is within the field of view of the optical alignment system, and describes the use of a control lever. command to manually place the test axes or use three electric motors controlled by information obtained from the optical alignment system to automatically place the instrument.

SHORT PESCRIPTION PH THE DWgMTT? M An optical instrument includes a lever mounted on a sphere, controlled manually, or joystick, to place an optical medium of the instrument, which includes a test axis and area detectors that define a field of vision, in relation to the eye of a patient. The optical medium is fixed to a support that can be moved vertically, which in turn is supported by a support that can be moved horizontally. The control lever mechanically moves the carrier in a horizontal plane relative to a frame to center the test axis and separate the optical means an appropriate distance from the eye. The control lever is connected to a motor pulse having a lifting motor for moving the support and optical means in any vertical direction. An actuator extends from the control lever and is arranged to alternatively couple a pair of switches connected to the motor pulse, so that the activation of the lifting motor and its direction of rotation can be controlled with a minimum rotational movement of the joystick around its longitudinal axis. The motor pulse is additionally connected to receive alignment signal information originating from the optical means, and control lever limiting control is provided to disconnect the joystick and automatically control the motor impulse to vertically align the Test axis with the center of the eye when the eye is within the field of view of the optical medium. Therefore, in accordance with the present invention, a physician operates the control lever to manually place the test axis vertically until it is within the field of view, and then the control lever limiting control automatically signals the pulse of the test pulse. motor complete the vertical alignment of the test axis with the center of the eye.

BBEYB 1BKqiTPfI < 5 OF THE Piamos The nature and mode of operation of the present invention will now be described more fully in the following detailed description of the preferred embodiments when taken with the accompanying drawing figures, in which: Figure 1 is a perspective view of a improved ophthalmic instrument embodying the present invention; Figure 2 is a top plan view of a control lever and switching means of the present invention; Figure 3 is a sectional view taken generally along the line 3-3 in Figure 2; Figure 4 is a side sectional view of an associated elevation limit lift and detector motor of the present invention; Figure 5 is a sectional view taken generally along the line 5-5 in Figure 2; Figure 6 is a bottom plan view of the control lever; Figure 7 is a block diagram of an ophthalmic instrument embodying the present invention; and Figure 8 is an electrical schematic diagram of the electronic systems of the motor control thereof.

An improved ophthalmic instrument in the form of a non-contact tonometer (NCT) and generally designated as No. 10 is shown in Figure 1. NCT 10 is conventional insofar as it includes a frame 12 having a carrier 14 that moves horizontally, a support 16 having axes 18 slidably mounted by carrier tubes 20 for movement of the support vertically in relation to the carrier 14 and horizontally with the carrier, optical means 22 fixed to the support 16 for testing a patient's eye centered at along the test axis 23 of the optical means, and a joystick 24 for controlling the movement of the optical means 22 in the three dimensions. The NCT 10 is preferably equipped with an optical alignment system of the type commonly described in commonly owned U.S. Patent No. 4,881,807. In accordance with the present invention, a lifting motor 26 is provided to automate vertical movement up and down of the support 16 and an optical means 22 in response to an activation switch 28a, and a deactivation switch 28b, activated alternately by an actuator 30. The actuator 30 extends radially from the control lever 24 and activates the commutators 28a, 28b incident to the minimum rotation of the joystick in any direction, for this way facilitate the vertical positioning of the test axis 23 in relation to the eye. As best seen in Figures 2, 3 and 6, the control lever 24 is generally of conventional structure, except for the actuator 30. The control lever 24 includes a handle portion 31 and is mounted in a known manner on the carrier 14 by a Teflon sphere 32 received within a complementary receptacle 34 and having slot means 36 for adapting a set of screws 38 which allow the coupled rotation of the control lever and the receptacle around the longitudinal axis of the lever. also controls the tilting movement of the joystick inside the receptacle. The control lever 24 includes a rounded teflon leg 40 arranged to engage a regular platform 42 fixed to the frame 12 through the entire range of movement of the carrier 14, and drive switching means 44 connected to an electrode 46 to activate the optical means 22. As shown in FIG. 6 only, the holding arm 48 is fixed to the underside of the carrier 14 for coupling below the platform 42 incident to the lifting movement exerted by the control lever 24.

The actuator 30 is fixed to the receptacle 34 to extend radially outwardly from the control lever 24 between the switches 28a, 28b, in a rotational reference position, so that it is operatively coupled to a switch shock absorber 50a for activating the incident switch 28b at the slight rotation of the control lever 24 in a clockwise direction and operatively engaging a switch shock absorber 50b to activate downward the incident switch 28d to a slight rotation of the joystick 24 in a counter-clockwise direction. The switches 28a, 28b are preferably normally open switches of the general type known as "micro" switches. Obviously, it is possible to use other similar switches. The switches 28a, 28b are connected by electrodes 51 to the electronic engine control system, described in detail in the following, which incorporates a limiter control for the joystick of the present invention. Referring now to Figures 2, 4 and 5, the lifting motor 26 is fixed to a lower member 52 of the support 16 and includes an internally threaded rotor (not shown) to match a threaded rod 54 having a fixed upper portion. to the carrier 14 by a mounting bracket 55 and a lower portion extending downward through the carrier 14 and a lower member 52. A motor suitable for use in the practice of the present invention is a 12-volt direct current, 4.6-watt bi-directional step motor, number 36343-12 available from Haydon Switch and Instrument, Inc. A limit and upper switch 56 and a lower limit switch 58 are mounted on a linker 57 and connected to the electronic control components of the motor by electrodes 59, and a tab 60 is fixed to travel with the lower member 52 to interrupt the light sensors on the switch 56 of upper limit upon reaching the upper displacement limit, and lower limit switch 58 upon reaching the lower displacement limit, whereby causes the respective limit switch to send a signal to the electronic control motor components to inactivate to the lifting motor 26 when any of the displacement limits is reached. A preferred limit switch is the optical transmitting switch model number HOA 1881-11 manufactured by Honeywell. The block diagram of Figure 7 illustrates in general terms the functional organization of the electronic components in the NCT 10. The NCT 10 is equipped with an optical alignment system in which the optical means 22 includes a pair of LEDs 62a, 62b to illuminate an eye, and a pair of CCD arrays, 64a, 64b, arranged in a known manner to define a field of view 66. The LEDs 62a, 62b and the CCDs 64a, 64b cooperate to generate signal information indicative of the position of the patient's eye within a field of vision 66. This information is passed to digitizing electronic components 68 which in turn provide a set of signals representing the X, Y and Z distances of the test axes 23 from the center of the eye towards the video electronic components 70. The video electronic components 70 also receive a macro video image signal from the eye from a video camera 72. The electronic video components 70 supply the output to a video screen 74 which provides visual alignment instructions to an operator, such as an orthogonal lens superimposed on the macro image of the eye. In addition, the electronic video components provide a vertical position signal Y 'representing a complete description of a preferred optical alignment system is provided in commonly owned U.S. Patent No. 4,881,807, issued November 21, 1989. In accordance with the present invention, the signal information is passed from the electronic video components 70 to the electronic control components of the motor 76. When the eye is out of the field of vision 66, the joystick 24 connected to the electronic components of motor control 76 provide the operator with means to manually place the optical means 22 and the test axis 23 with respect to the eye. However, when the eye is placed in the field of vision 66, the electronic control engine components 76 uses the information from the electronic video components 70 to limit the joystick 24 and automatically propel the hoisting motor 26 to vertically align the test axis 23 with the center of the eye. As previously mentioned, the upper limit switch 56 and the lower limit switch 58 provide a signal to the electronic engine control components 76 to inactivate the lift motor 26 when any vertical travel limit has been reached. Now, with reference to Figure 8, the electronic engine control components incorporating the joystick limiter of the present invention are schematically represented. The lifting motor 26 is connected to the output lines 78-81 corresponding to the legs 4, 6, 7 and 9, respectively, of a motor driver 84, which is preferably a full-bridge motor driver. double model number UDN2998W available from Allegro. The legs 3 and 11 of the motor driver 84 are associated with the motor activation input line '86. The motor driver 84 is responsive to the motor drive signal under the logic of the line 86 to allow the motor 26 to rise, while the logic high motor drive signal will inactivate the motor 26 from elevation. The motor driver 84 is additionally responsive to a pair of phase input signals carried on the lines 88 and 90 connected to the pins 2 and 12, respectively. The lifting motor 26 is activated manually, for example by the control lever 24 engaging the switches 28a and 28b, or automatically, when an eye enters a field of vision 66 of the optical means 22, to move the shaft 23 test vertically for alignment with the center of the eye. The motor driver 84 is connected to a stepper motor driver / impeller 92, preferably the model number UCN5804B manufactured by Allegro, to control the gradual speed and direction of rotation of the motor 26. The shuttle / impeller 92 includes a motor activation input on leg 15 for receiving the motor activation signal carried on line 86, an address input on leg 14 for receiving an address signal carried on line 94, a speed input step-wise in leg 11 to receive a clock pulse signal carried by line 96, and a pair of outputs in pins 1 and 8 connected to phase input legs 2 and 12 of motor driver 84 by lines 88 and 90, respectively. A first 8-bit comparator 100 is connected, preferably the Texas Instruments model number SN74HC682, connected to receive an 8-bit vertical position Y1 signal on legs 2, 4, 6, 8, 11, 13, 15 and 17 thereof transmitted by electronic components 70 of video over a common link 102 and and includes a mode selection output on the leg 19 for transmitting a mode selection signal on the line 104. The first comparator 100 determines whether the vertical position signal received via the common link 102 Y is equal to a null octet supplied to the legs 3, 5, 7, 9, 12, 14, 16 and 18 thereof. When the eye is out of the field of vision 66, the vertical position signal is equal to a null octet, and the mode selection output signal is deactivated for the manual control mode (by means of the joystick); conversely, when the eye is within the field of vision 66, the vertical position signal is different from a null octet, and the mode selection output signal is driven to activate towards the automatic control mode.

The mode selection signal is preferably provided by means of the line 106 through a first logic means 110, which will be described in detail in the following, and subsequently inverted by an investment 111 before it is supplied. to a second logical medium 120 appropriately the National Semiconductor model number MM74HC157 Quad 2-Input Multiplexer. The second logic means 120 includes a selection input on leg 1 to receive the signal of the selection mode and any of the connection switches 28a, 28b, to the motor drive means 84 and 92 when the mode selection signal received is activated, or to disconnect the switches from the motor drive means and connect the electronic video components 70 thereto to carry out automatic alignment when the received mode selection signal is inactivated. The second logic means 120 additionally includes a first motor drive input on the leg 3 and a first motor address input on the leg 6 connected to the switches 28a, 28b along the lines 112 and 114, respectively, for control of the manual motor, and a second motor activation input in the leg 2 and a second motor direction input in the leg 5 connected to a second comparator 130 by the lines 116 and 118, respectively, for automatic motor control. The activation switch 28a and the deactivation switch 28b are each connected to a gate O (OR) 122 whose output is supplied on line 112, so that when either of the switches is closed, the motor activation signal supplied to leg 3 input is activated. The deactivation switch 28b is connected directly via line 114 to the input leg 6 to activate the incident high address signal to close the inactivation switch. The second comparator 130 is connected to the common link 102 Y to receive the vertical position signal Y 'which represents the position Y of the center of the eye in relation to a selected video display reference, and includes an output of motor activation in the leg 19 and a motor direction output on leg 1 connected to legs 2 and 5 of second logic means 120 along lines 116 and 118, respectively. The second comparator 130 compares the vertical position signal with a predetermined 8-bit signal supplied to the legs 3, 5, 7, 9, 12, 14, 16 and 18 thereof which represent an optimum Y position of the axes 23 of test in relation to the reference of video exhibition mentioned in the above. If the vertical position signal Y 'is smaller than the predetermined optimal position signal, then the center of the eye is below the test axis 23 and the output of the motor direction signal of the leg is activated for movement toward below the test axis. Conversely, when the vertical position signal is greater than the predetermined optimal position signal, the motor direction signal is deactivated for upward movement of the test axis. Once the test shaft 23 is moved by the lifting motor 26 so that the vertical position signal Y 'is equal to a predetermined optimum position signal, the automatic vertical alignment and the motor activation signal are obtained from the leg 19 is deactivated to inactivate the lifting motor 26. As described above, the upper limit switch 56 and the lower limit switch 58 are provided to inactivate the elevation motor 26 when the test axis 23 reaches a predetermined upper displacement limit or a predetermined lower displacement limit, respectively. The upper limit switch 56 and the lower limit switch 58 are connected as first inputs to Y gates (AND) 132 and 134, respectively. The output of the direction signal from leg 7 of second logic means 120 is inverted by inverter 136 and is supplied as a second input to gate Y (AND) 132. An inverter 138 serves to provide a signal of opposite direction as a second input to a gate Y (AND) 134. The output signals from the AND gates (AND) 132 and 134 are passed to a gate 0 (OR) 140, whose output in turn is supplied to a gate O (OR) 142. The input of the direction signal to a gate Y (AND) 132 during the upward travel of the elevation motor 26 which is activated, the input of the signal to a Y (AND) gate 132 from the upper limit switch 56 is driven in an incident activated manner to the elevation of the motor 26 when it reaches its upper displacement limit, which results in an activated signal being supplied to the gate O (OR) 140 and subsequently to gate O (OR) 142. Accordingly, the motor block signal leaving the gate O (OR) 142 is driven high to inactivate the lift motor 26. The lower limit switch 58 works in a similar manner by means of a Y (AND) gate 134, with the address signal input thereto activated high during the downward displacement of the elevation motor 26. The clock pulse supplied via line 96 to leg 11 of shuttle / pusher 92 controls the speed of passage of lift motor 26. When the motor drive means is under manual control, a fast clock pulse rate is provided for, correspondingly, a fast vertical movement of the optical means 22.; when the motor drive means is under automatic limiting control, a relatively slow clock pulse rate is provided for, correspondingly, a slower vertical movement of the optical means 22. The clock pulse synchronizer originates with the provision of a horizontal synchronization signal from the video electronic components 70 on the line 148 to a binary / divider counter means 150, which may be a Harris CMOS Ripple binary counter / divider. Carry model number CD4040B having a pulse input on leg 10 and a reset input on leg 11. The horizontal synchronization signal from electronic video components 70 has a typical frequency of 15,750 Hertz, which is divided by 64 to produce a fast clock pulse rate output from leg 2, and is divided by 256 to produce a slow clock pulse rate output from leg 13. The fast and slow clock pulse rates are supplied over the lines 152 and 153 to gates Y (AND) 154 and 155, respectively. In addition to the fast clock pulse rate, gate Y (AND) 154 receives as input the selection signal so that it originates from the first comparator means 100 inverted by inverter 111. Gate Y (AND) 155 receives as input the non-inverted mode selection signal for evaluation with the slow clock pulse rate. The outputs of AND gates 154 and 155 are passed through gate O (OR) 158. Consequently, the non-inverted mode selection signal is logic inactivated or low for manual control mode, the Slow clock pulse rate will be blocked at gate Y (AND) 155 and the fast clock pulse will be transmitted through gate Y (AND) 154 and gate 0 (OR) 158 to line 96 for entry to the leg 11 of the shuttle / driver 92. When the non-inverted mode selection signal is high logic for automatic mode, the slow clock pulse rate will be passed to the shuttle / driver 92 in a similar, but opposite manner. The first logic means 110 is suitably a semiconductor National model number MM74HC157 Quad 2-Input Multiplexer identical to the second logic means 120 and includes legs 2 and 4 for the respective input and output of the mode selection signal transmitted by the first comparator 100 on line 106, and legs 6 and 7 for the respective input and output of a cross-line signal supplied from electronic video components 70 on line 160. First logic means 110 additionally includes a leg 1 selection input preferably connected to externally accessible blocking means 162 for driving the high selection input, whereby the mode selection signal can be selectively derived to disconnect the automatic limiting control to provide control exclusive manual by the joystick 24 and the switches 28a, 28b with a reticle screen. The provision of a blocking means 162 allows the technician to perform the initial calibration and alignment of the NCT 10. As can be seen from the above description, the NCT 10 is significantly easier to operate compared to the prior art ophthalmic instruments. , particularly with respect to the vertical positioning of the test axis 23. To manually raise the test axis 23, an operator only rotates the control lever 24 in a clockwise direction through a minimum angle, until the actuator 30 is operatively coupled with the switch shock absorber 50a, on the switch 28a, to thereby cause the internally threaded rotor of the lift motor 26 to rotate in a first direction, drive: the lift motor and the support 16 attached thereto to move upwards, along threaded rod 54. Based on the type of switch 28a, the upward displacement of the optical means 22 can be stopped either by returning the control lever to its original reference position, away from the coupling with the shock absorber 50a of the switch, or by repeating a cycle of "turn and return" used to start the movement up. The manual downward positioning of the test shaft 23 starts in a similar, though opposite manner, by rotating the control lever 24 counterclockwise from its reference position until the actuator 30 is operatively coupled with the commutator shock absorber 50b. Once the eye is within the field of vision 66, the control lever limiter control of the present invention performs automatic vertical alignment of the test axis 23 with the center of the eye. Although the present invention has been directed to the motorized movement in opposite vertical directions (Y) the motorized movement in the three dimensions has been previously described, for example, in the U.S. patent mentioned in the above number 4,881,807 in column 6, lines 31- 44 and FIG. 7, and is therefore considered to provide similar motorized movement in the X and Z horizontal directions in combination with the manual and automatic limiting control therefor.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it refers. Having described the invention as above, property is claimed as contained in the following:

Claims (9)

1. BBtvtt? Ntfa. rO »flB i- An alignment limiting device for ophthalmic instrunen, characterized in that it comprises: a test shaft passing through the instrument, a motor drive means for moving the shaft vertically, a first switch for activating the drive means in one direction , a second switch for activating the driving means in the other direction, manual means for selectively coupling the first or second switches to provide manual control of the driving means, optical means having a field of view and means for detecting the position of a eye, the optical means include signal means for generating a signal having a value representing a vertical position of the eye in relation to the axis when the eye is within the field of vision, and a comparator means for determining at what time the means of signal generates a signal, and a displacement control from the first and second switches towards the signal, so that e the optical medium is in exclusive control of the driving means if the eye is within the field of vision.
2. 2. The limiter according to claim 1, characterized in that the manual means is a control lever.
3. 3. The limiter according to claim 2, characterized in that an actuator protrudes from the hand lever for selective engagement of the first or second switch when the control lever is rotated.
4. 4. The limiter according to claim 1, characterized in that the signal is a digital signal.
5. 5. The limiter according to claim 4, characterized in that the drive means includes a stepper motor and a stepper motor driver having a gradual or gradual speed input responsive to the clock pulses.
6. 6. The limiter according to claim 5, characterized in that the comparing means additionally includes means for providing a clock pulse rate for manual control of the driving means and another speed of the clock pulse when the optical means is in exclusive control of the drive medium.
7. 7. The limiter according to claim 6, characterized in that a clock pulse rate is faster than the other pulse rate of the reLoj.
8. 8. The limiter according to claim 6, characterized in that the comparing means additionally includes means for locking or electrical closing, to temporarily avoid exclusive control by the optical means.
9. 9. Improved non-contact tonometer that has an optical medium that includes a pair of light sources to eliminate an eye, a pair of XY area detectors that has a field of view, and a test axis, manual means to move the optical medium in relation to the eye, electronic digital components to provide an X signal, a Y signal and a Z signal when the eye is within the field of view, the X and Y signals represent the respective distances X and Y of the test axes from the center of the eye and the signal Z represents the distance of the optical medium from the eye along the test axis; camera means for providing a recorded image of the eye, video electronic components for processing the X, Y and Z signals, and providing a television signal representing the recorded image and a symbol, the television signal includes a vertical position signal which represents the position Y of the center of the eye in relation to a video display reference; and a television monitor to display the recorded image and symbol; which tonometer is characterized because the improvement comprises: - a motor drive means for moving the optical medium vertically; a first switch and a second switch that can be selectively disconnected from the driving means to activate the driving means and control the direction of vertical movement; a first comparator means for evaluating the vertical position signal and providing a first output from the compactor that indicates whether the eye is within the field of view; a second comparator means for evaluating the vertical position signal and providing a second comparator output indicating the vertical direction at which the optical means moves to align the test axis with the center of the eye; and logical means for evaluating the first output of the comparator and disconnecting the first and second switches if the eye is within the field of view, and to evaluate the output of the second comparator and activate the drive means and select the vertical direction to move the medium optical. SSSSSB? FROM THE IMVBfCl? N An alignment limiting control is described for performing automatic vertical alignment of a test shaft in an ophthalmic instrument (10) with the center of an eye. The test axis is associated with optical alignment means of the instrument that can be moved vertically by a lifting motor controlled by an engine impeller. A control lever (24) and a pair of directional switches (28a, 28b) are connected to the motor pulse for manual positioning of the test axis. When the eye is placed within a field of vision defined by the optical means, the limiting control disconnects the limiters and automatically signals the lifting motor to perform automatic alignment using signal information originating from the optical medium.