Title:
Ultrasonic/chemical cleaner for contact lenses
United States Patent 3871395
Abstract:
Apparatus for ultrasonically and chemically cleaning contact lens of all types which utilizes a relatively high ultrasonic frequency at an intensity level which is higher than normally would be considered for such small items, so as to cause the cleaning fluid to be emulsified and reach molecular bond-breaking levels, and so as to cause intense cavitation. The cleaning fluid is raised to a high temperature for medical sterilization. The cleaning device includes automatic control so that the lens may be automatically cleaned, and the cleaner will then disable itself.
US Patent References:
Nursery utensil
Meyerson - August 1937 - 2088658
Acid pickling bath device
Franzwa - October 1939 - 2177101
Cleaning machine
Schouw et al. - June 1963 - 3094999
Apparatus for generating ultrasonic vibrations in liquids
Sasaki - March 1966 - 3240963
ELECTRIC SONIC DEVICE FOR CLEANING SMALL ARTICLES
Piccolo - February 1972 - 3640294
Nursery utensil
Meyerson - August 1937 - 2088658
Acid pickling bath device
Franzwa - October 1939 - 2177101
Cleaning machine
Schouw et al. - June 1963 - 3094999
Apparatus for generating ultrasonic vibrations in liquids
Sasaki - March 1966 - 3240963
ELECTRIC SONIC DEVICE FOR CLEANING SMALL ARTICLES
Piccolo - February 1972 - 3640294
Application Number:
05/335822
Publication Date:
03/18/1975
Filing Date:
02/26/1973
View Patent Images:
Export Citation:
Assignee:
Fibra-Sonics, Inc. (Chicago, IL)
Primary Class:
Other Classes:
D24/218, 134/143, 134/901, 134/184, 134/117, 366/114, 206/5.100
International Classes:
A45C11/00; B06B1/06; B08B3/12; B08B11/02; G02C13/00; B08B11/00; B08B3/10; B08B11/02
Field of Search:
134/1,107,117,143,105,184 206/5A 259/DIG.44
US Patent References:
Primary Examiner:
Bleutge, Robert L.
Attorney, Agent or Firm:
Hill, Gross, Simpson, Van Santen, Steadman, Chiara & Simpson
Claims:
1. An ultrasonic lens cleaner comprising:
2. An ultrasonic lens cleaner according to claim 1 comprising:
3. An ultrasonic lens cleaner according to claim 2 including a third timer connected to said ultrasonic generator and to said heating means to deenergize said generator and heater at a predetermined period of time after said units have been energized.
4. An ultrasonic lens cleaner according to claim 1 wherein said heat resistant pot holder is made of ceramic.
5. An ultrasonic lens cleaner according to claim 1 wherein said heat resistant material is pot holder is made high temperature filled epoxy.
6. An ultrasonic lens cleaner according to claim 1 wherein said heating means is spirally wound about said pot holder.
7. An ultrasonic lens cleaner according to claim 1 wherein said ultrasonic crystal is connected to said ultrasonic generator so as to form at least a portion of the frequency determining means of said generator so that the generator is matched to said crystal during temperature changes.
8. An ultrasonic lens cleaner comprising:
9. An ultrasonic lens cleaner comprising: a lens holding cup in which lenses to be cleaned and cleaning fluid are contained,
10. An ultrasonic lens cleaner according to claim 9 wherein said lens holding means comprises a partition member formed with openings therein attached to said lid, and a pair of lens holders attached to said partition member and formed with openings to freely admit ultrasonic energy into the space between said lens holder and said partition to allow cleaning of lens placed therein and to permit free movement of said lens.
11. An ultrasonic lens cleaner according to claim 10 wherein said pair of lens holders are pivotally attached to said partition member.
12. An ultrasonic lens cleaner according to claim 9 wherein said lid is formed with a T-shaped slot and said closing means is a T-shaped member receivable in said slot and formed with an opening that can be aligned with said opening in said lid.
13. An ultrasonic lens cleaner according to claim 9 wherein a bail is pivotally attached to the cylindrical pot holder and is movable to lock said lens holding cup to said pot in sonic contact.
2. An ultrasonic lens cleaner according to claim 1 comprising:
3. An ultrasonic lens cleaner according to claim 2 including a third timer connected to said ultrasonic generator and to said heating means to deenergize said generator and heater at a predetermined period of time after said units have been energized.
4. An ultrasonic lens cleaner according to claim 1 wherein said heat resistant pot holder is made of ceramic.
5. An ultrasonic lens cleaner according to claim 1 wherein said heat resistant material is pot holder is made high temperature filled epoxy.
6. An ultrasonic lens cleaner according to claim 1 wherein said heating means is spirally wound about said pot holder.
7. An ultrasonic lens cleaner according to claim 1 wherein said ultrasonic crystal is connected to said ultrasonic generator so as to form at least a portion of the frequency determining means of said generator so that the generator is matched to said crystal during temperature changes.
8. An ultrasonic lens cleaner comprising:
9. An ultrasonic lens cleaner comprising: a lens holding cup in which lenses to be cleaned and cleaning fluid are contained,
10. An ultrasonic lens cleaner according to claim 9 wherein said lens holding means comprises a partition member formed with openings therein attached to said lid, and a pair of lens holders attached to said partition member and formed with openings to freely admit ultrasonic energy into the space between said lens holder and said partition to allow cleaning of lens placed therein and to permit free movement of said lens.
11. An ultrasonic lens cleaner according to claim 10 wherein said pair of lens holders are pivotally attached to said partition member.
12. An ultrasonic lens cleaner according to claim 9 wherein said lid is formed with a T-shaped slot and said closing means is a T-shaped member receivable in said slot and formed with an opening that can be aligned with said opening in said lid.
13. An ultrasonic lens cleaner according to claim 9 wherein a bail is pivotally attached to the cylindrical pot holder and is movable to lock said lens holding cup to said pot in sonic contact.
Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to apparatus for cleaning and rejuvenating contact lens of the hard and soft types, and in particular to an automatic lens cleaner.
2. Prior Art
The first use of lens dates back to antiquity in that lens were used by the ancient Romans and perhaps even by the Greeks. Fairly well refined lenses were fabricated as early as 1052 A.D., and Salvino l'Armato degli Armati constructed the first spectacles wearable on the nose in the year 1255 A.D.. Continuous progress has been made since that date, with new inventions and and discoveries in this field being put into almost immediate use. Some such developments were not always beneficial to the user.
Many different types of lenses for spectacles are used, and they are as varied as the defects in human vision. For example, such lens may be convex, bi-concave, concave-convex, segments of planes, cylinders and spheres. They may also be panascopic (dual) and periscopic (a divergent menicus lens). Much attention and development has resulted from the cosmetic or vanity aspects of spectacles, so as to render the wearer and/or the spectacles attractive. For example, spectacles of complicated and odd configurations have been constructed, many of which have been quite beautiful. Some such spectacles have been jeweled and have been very expensive.
Human vanity has probably led to the tremendous amount of work done in the United States and abroad on contact lenses. Such lens are directly placeable over and on the eyeball, thus, dispensing with all external signs of malvision since such lenses are not discernible by an observer. The exact date of the invention of contact lens has not been precisely resolved, and their discovery is claimed by inventors in several countries. About 1952 such lens were introduced in the United States with all of their unanticipated difficulties and concealed problems which were not obvious at that time. Even today many of the problems inherent with contact lenses are not generally recognized or understood.
One of the major problems resulting from the use of contact lens is that the insertion of any foreign body, no matter how small or sterile, into the eye will be treated by the living eye as a foreign body which will marshal the normal therapeutic, physiological reactive forces, so as to combat and to try to dislodge the intruder. Thus, the introduction of "hard" contact lenses created a need for a better understanding of the nature of the corneal edema problem and its solutions. Many articles and patents have appeared on this problem in, for example, the Journal of the American Pharmaceutical Association and the Journal of Ophthamology. Such literature illustrates that the problems of using contact lens of both the soft and hard type are many and complex.
Hard contact lens cannot be made of glass due to the danger of breakage and subsequent injury to the eyeball, but danger of methylmathacrylate plastic commonly known as "Plexiglas" in the United States or abroad as "Lucite." Hard lens are quite small, usually being in the range of 5 to 12 milimeters in diameter, are usually disc shaped and usually possess a concave-convex grind. As the art has advanced other types of shapes and more complex lens grinding has been attempted with some success. The advantage of using one of the many methylmethacrylate formulations for contact lens lies in their excellent optical refractive properties, which is of course a prime consideration in lens making, also in their durability and of most importance, for biological reasons, hygroscopic hygrosopic nature. Non-hygroscopic glass was ruled out for use in contact lens at a fairly early date. The disadvantages of plastic is that methylmethacrylate lens are easily scratched if handled carelessly or for example, if cleaned with mechanical rubbing or with abrasives. They are also easily damaged by the use of improper chemical cleaning agents, and if allowed to dry out when in storage will distort, sometimes irreversibly, and will become discolored or "fogged" and brittle. Also due to their hygroscopic nature and the environment in which they are used, body salts carried by the lachrymal fluids are concentrated in the lens, and if allowed to dry create deposits which can cause irritation and serious edema in the human eye when reused. Such deposits are very difficult to remove since they are embedded into the plastic and do not merely lie on its surface.
The problems associated with hard contact lens made it apparent at an early date that it would be desirable to develop a softer material. The less solid the material which is placed into the eye, the less is the haste of the biological rejection and in going from a solid to a less hard plastic to a soft plastic less difficulty in rejection by the eye is encountered. The ideal lens would be a liquid, however semi-liquid lens of a substance matching the soft living tissue, which is completely non-toxic in nature and to nature, would be highly desirable. Otto Wichterle of Czechoslovakia, who started on such an approach as early as 1963, has succeeded in fabricating soft lens using anyhydrous, sparingly cross-linked hydrophilic copolymers consisting of 98% by weight of water soluble monesters of a crylic or methacrylic acids. Such lens when dehydrated are hard enough to work and can be cut, ground and polished. When these lens are exposed to water, they swell to a predeterminable shape of precise size and become exceedingly soft and "skin-like" while maintaining their optical transparency and their refractory characteristics.
Such gelatinous soft lenses, being extremely hygroscopic, have previously had to be kept in a sterile liquid solution at all times. They must also be very carefully handled, and due to their "culture" nature must be preserved from bacterial and viral contamination. Such lenses in their nascent state are called "Xerogels" by Wichterle and "Hydrogels" after they have been swelled to their final size. Being highly porous, i.e., osmotic membranes, the interpenetration of impurities and natural body salts are severe and are even more difficult to remove. Such lens are very expensive and the above problems have resulted in such lens being utilizable for only a short lifetime before they become unusable and must be replaced.
Both the hard and soft type lenses are plastic and therefore are easily scratched or damaged, thus making cleaning by direct handling difficult. Both types of lens are hygroscopic and permit interpenetration of undesirable body salts and poisons, and invasion by microbes and viri, thereby making sterilization necessary, but extremely difficult. Also both types of lenses if permitted to dry out become damaged, distorted, discolored, or contaminated beyond acceptable or safe use.
Various devices and methods have been used in the past to try to clean hard and soft lenses. One approach, for example, is to keep the lens submerged in sterile water at all times when not in the eye. Various jets and plungers have been used to agitate the liquid cleaning solutions in which the lens are immersed. Another approach is one which stores the lens in a carrying case which is then subjected to the pressure of local tap water or to overnight soaking and rinsing by hand. Several writers on the prior art have indiscriminately recommended the use of detergent soaps and medical germicidal solutions for cleaning and soaking. However, such cleaners, which may be excellent for pots and pans, can be highly dangerous for use in cleaning contact lenses because the lens pick up and retain in their pores part of the detergent and medical germicidal chemicals. Such materials can be very dangerous to the human eye when they are leached out of the interior surface of the lens by the lachymal fluid onto the eyeball. Such cleaning chemicals quite probably have caused many of the numerous documented cases of infection, edema, and serious eye damage to contact lens users.
Hard methylmethacrylate lens cause much discomfort due to the hydrophilic nature of their surface and complaints of fogging and irritation have been common. Even though the plastic is capable of hydration, it will not readily do so and many surfactants are ineffective. As stated by Bancroft in the Journal of Physical Chemistry 1913, the interfacial tensions between a solid and a liquid, for example, are lowered by the formation of a molecular film which contains a mixture of the molecules from the surfactant and from the two materials, which in the case of lenses is methylmethacrylate and water. This surfactant film has two interfacial tensions, one with the water and one with the plastic. Depending solely on the ionic potential present, the hydrophilic portion may attach itself to the methylmethacrylate plastic or onto the water. If the hydrophilic surface is attached to the plastic, then a new outer surface is formed which will act to repel (hydrophobic) water and any water soluble chemicals in the solution. If such an event takes place, no cleaning will be effected and ocmplete sterilization can not take place and the viri and microbes will become entrapped in the interior of the lenses.
Attempts have been made to solve this problem by the use of proper ionic wetting solutions which were slightly hypertonic in nature, and exhibited the desirable characteristics. Many contact lens wearers develop mild or severe edema of the corneal epithelium which is believed to be caused by the drying out of the surface directly behind the lenses. However, recent research, including my observations, have shown that this damage is caused by chemical irritants as well as by mechanical irritation. Such chemical irritants not only may not be removed during the cleaning process, but may actually be supplied to the lens from the cleaning fluid during the cleaning process. I have discovered that the approaches utilized by the prior art have not fully understood the nature of the problem and its answer which is the providing of super-cleaning including deep inside the interstial porous cavities in a manner and with cleaning solutions which are completely safe and non-irritant.
SUMMARY OF THE INVENTION
The present invention relates to a method and apparatus for the deep cleaning of lens of various sorts. Although the use of ultrasonic energy for cleaning of lenses has been suggested, the successful application of ultrasound to cleaning hard and soft lens has not been accomplished prior to my invention. I have discovered after exhaustive tests and measurements that it is the porous, hygroscopic nature of the lens themselves, which make it necessary to utilize a great deal of physical and chemical knowledge to obtain the superior cleaning of my invention. Low frequency ultrasound commonly used in industrial cleaners such as a frequency of 20kHz failed to cause penetration of the fluids into the membranes of the lens, and I have discovered that it is necessary to use a higher frequency such as 40 to 100 kHz to accomplish effective deep cleaning.
In addition I have discovered that the intensity level of the ultrasonic energy required for penetration was far greater than what would normally be considered as needed for such small items as contact lens. I have discovered that intensities in the order of 10-20 watts per square centimeter are required. This level is an emulsifying, molecular bond-breaking level of sonic energy, but such an energy level is needed to truly interpenetrate the interstial regions of the lens for deep cleaning. Lower energy levels or lower frequencies cannot accomplish the thoroughly cleaning and rejuvenation of the lens as does the methods and apparatus of my invention.
In summary then: two cleaning phenomena must occur; one is the intense cavitation of ultrasonic emulsification and the other is the high liquid temperatures approved for medical sterilization of objects wherein it has proved necessary to elevate the liquid solutions used to 170° to 200° F. Such temperatures tend to prevent cavitation and mistune the ultrasonic cleaning generator drive system, which are additional problems solved by my invention.
Finally, my invention encompasses the proper, high temperature germicidal ingredients, surfactants, and surface tension increasers in the cavitating cleaning fluid. This fluid must have a high osmotic pressure, must readily cavitate and must permit ultrasonic energy to easily flow through the fluid as well as through the membraneous porosity of the hard and soft lens at temperatures of 170° to 200° F. This is especially true for the soft lens.
Problems associated with meeting all of these complex requirements make it difficult to design a device and to obtain a fluid which finally results in a super-cleaning (including the interior) of the lens that is completely safe and comfortable for the user, and which will provide a lens lifetime many times that of lens cleaned and used under present methods.
During the course of my research it was found possible to contaminate lens with extremely small particle sized radioactive molybdenum which penetrated through the porous methylmethacrylate material. This penetration phenomenon also appears even more pronouncedly in the soft lens and when they were dried it was readily perceived. The heaviest of contamination, using the smallest molecular cross-sectional materials, was tried using even viri size contaminants. Also all sorts of normal contaminants such as lipstick, other make-up, dirt and dried-on body salts of all types were used. In every case, normal cleaning as recommended by the various pharmaceutical houses and lens makers cleaned only partially while the devices and chemicals used in my invention completely succeeded.
One unexpected result which was entirely unforeseen, was the rejuvenation and reconstitution of the copolymer soft lens wherein they could be dired out and reconstituted tens of times without damage to their structures or dimensions. This is in contrast to present methods of cleaning wherein when these lens are once dried out they lose their usefulness, change dimensions, discolor, warp and frequently must be discarded. The application of intense ultrasound in the present invention reconstitutes the copolymeric purity and molecular structure of the lens for reasons not entirely understood, and old dried out lens treated by the apparatus in methods of the invention resulted in clear, fog-free lenses with no discoloration and a return to the skin-like texture that is well known to be desirable. All brittleness, fragilibility and contamination was removed in 1 to 2 minutes application of the heat, chemicals and high intensity ultrasound of the invention.
It is an object of the present invention to clean ocular and other types of lenses, of the hard type and of the soft, tissue-like types.
Another object of the invention is to sterilize lenses of all bacteria, fungi and viri.
Still another object of the invention is to clean, sterilize and reconstitute the membraneous materials of the lens deep in the pores and throughout the pore structure.
Another object of the invention is to provide an automatic cleaning machine for lens.
Yet, another object that is provided is ease of user storage and simplified transporting apparatus for lens.
Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure and in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1, is an exploded perspective view of the invention,
FIG. 2, is a partial cutaway view of the invention,
FIG. 3, is an electrical schematic of the invention,
FIG. 4, illustrates the operation of the cylindrical sonic energizer of the invention,
FIG. 5, is a plot of pressure v. distance from the axis response of a cylindrical driving crystal radially polarized,
FIG. 6, is a sectional view illustrating construction of the pot heater ultrasonic actuator and thermal cutout,
FIG. 7, is a detailed sectional view illustrating the bonding and insulation,
FIG. 8, is an electrical schematic of the self-tuning electronic driving generator,
FIG. 9, is a sectional view of the cleaner with the lens holder and lens in place,
FIG. 10, is a sectional view of a one piece modification of the invention,
FIG. 11, is an enlarged perspective view of the cap and double trap door cleaning cage in which the lens are placed,
FIG. 12, is a detailed exterior view of the cap and;
FIG. 13, is a sectional view of a modification of the invention using an end driven ultrasonic motor.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates the cleaner of this invention which comprises a base member 11 which has an on-off switch 12 and a power cord 13, and a "cleaning-ready" indicator light 14. A hollow cylindrical support member 16 extends upwardly from the base 11 and supports a heating and driving cylindrical pot 18 and an outer cover 17. Lens cup 19 has a tapered cylindrical portion 21 which mates with the inner diameter of the heater and driver 18, and has an upper portion 22 which is threaded so as to threadedly receive the lens cap holder 23, which includes the cap 24 which is internally threaded to mate with the threads 22, and which has pivoted lens holders 42 and 52, which are pivotally attached to the center partition member 37 of the cap 23. The cap structure is best shown in FIGS. 11 and 12 and let it be noted that the inside portion of the cap 23 is threaded as shown by numeral 36, and has a hand portion 26. The center partition 37 is connected by the extension 38 to the inside of the cap 23, and has a first lens holder 42 pivotally attached by the hinges 43 and 44 to the portion 37. A spring clip 46 engages a notch 47 of the number 37 to lock the holder in the closed position. A center portion of the holder 42 is formed with openings defined by spokes 48 and 49, which form an enclosing cage in which the lens 51 may be placed. The partition 37 is formed with openings between the spokes 39 and 41 as shown in FIG. 11. The second holder 52 is similar to the holder 42 and the second lens is receivable therein.
As shown in FIG. 12 the handle portion 26 of the cap 24 may be formed with a T-shaped slot 25 in which is received a mating T-shaped member 29, which has a vertical portion 31 and a horizontal portion 32. A pair of openings 27 and 28 are formed in the cap 24 and mate with slots formed in the T-shaped member 29 when it's moved to a certain position so that rinsing water or cleaning fluid may be poured into the opening 28 through the slot 34 into the lens container and flow out through the associated slot and opening 27. A detent 33 is formed in the member 29 to hold it in a preset position.
FIG. 2 is a cutaway view of the bearer and drive unit with the lens cup 19 and cap 23 mounted therein. The heater and driver 18 comprises an inner cylindrical member 18a, made of ceramic or high temperature epoxy, which has embedded in it a heater 20 that might be made of chromal V heating element of approximately 130-200 ohms. Surrounding the inner cylindrical member 18a is radially polarized piezoelectric crystal 18b of generally cylindrical shape which is tightly bonded to the cylindrical holding/heater unit 18a.
The crystal is in turn embedded in a cylindrical holder 17 which might be of a room temperature vulcanizing elastomer of durometer 20 to 70 units.
The oscillator drive unit 62 is connected by leads 63 and 64 to the crystal 18b. Thermal cutout 25 is connected to the heater 20 and to the 80 second timer 61 by leads 66 and 67. The timer 61 is connected to the oscillator 62 and to a 3 minute timer 68 which is connected by the power cord 13 to a power plug 69 to supply power to the unit.
The actual electrical schematic is shown in FIG. 3, wherein the power plug 69 is connected to a first lead 71 which is connected to the on-off switch 12 and to a fuse 72. The other power lead 73 is connected to a heater element of the 3 minute timer 68. The other side of the heater element 68 is connected to the fuse 72 by lead 74. A pair of normally closed contacts 76 and 77 are opened by the heater 68 after a preset time, as for example, 3 minutes, so as to turn the cleaner off. Contact 76 is connected to lead 74 and contact 77 is connected to the oscillator 62 and to the "cleaning-ready" light 14 which has its opposite side connected to lead 73. The other lead to oscillator 62 is designated 79 and is connected to normally open contact 81 which mates with contact 82 which is connected to lead 83. The 80 second timer 61 has a resistive element which has one side connected to lead 74 and the other side is connected to lead 73. Lead 83 is connected to one end 84 of the pot heater winding 20 and the other end 86 of the pot heater winding is connected to lead 73. The thermal cutout 25 includes a pair of normally closed contacts 87 and 88. Contact 87 is connected to lead 83 and contact 88 is connected to lead 78.
The cleaner operates as follows:
When the on-off switch 12 is closed power will be applied to the heater 61 and the heater 68 simultaneously starting their counting cycle. Power will also be supplied to the pot heating element 20 through lead 73 and normally closed contacts 76 and 77, and through contact 87 and 88 of the thermal cutout unit 25. This will cause the cleaning fluid inside the cup 19 to be brought up to a temperature of 170° F. in approximately 75 seconds. At this time the contact 87 and 88 open which disconnects power from the pot heater 20. The cleaning fluid in the pot 19 will continue to rise to approximately 194° F. during the next 5 seconds at which time thermal delay relay 61 closes contacts 81 and 82 to apply A.C. line voltage to the ultrasonic oscillator 62 input terminals, through pot heater element 20, and sonic energy will be supplied to drive the crystal 18b from the oscillator 62. The 3 minute thermal timer 68 disconnects power completely from the heater as well as the oscillator by opening contact 76 and 77 and indicator light 14 goes out indicating cycle is over.
FIG. 4 illustrates the radially polarized piezoelectric vibrating element 18b which when excited through leads 63 and 64 by oscillator 62, supplies sonic energy into the interior of the cleaning cup 19. FIG. 5 illustrates the high sonic pressure generated in the cleaning cup 19 plotted as a function of distance from the center axis of the cup. It is to be noted that the cleaning pressure is maximum near the center axis of the cleaning cup where the lens are disposed.
FIG. 6 is a more detailed sectional view of an actual working model constructed and operated. The ceramic pot 18a has embedded in its outside wall the heating coil 20 of about 150 ohms. The pot 18a is then bonded to the cylindrical crystal drive element 18b by high temperature epoxy 91, which is capable of withstanding 700°-800° F.. Alternatively, the bonding may be accomplished by a ceramic cement. Also portions of the heater winding 20 may be embedded in the base 92 of the pot 18a to provide temperature anticipation sensing. This portion of the heater element is designated 93 in FIG. 6. The crystal 18b and pot 18a are surrounded by a relatively soft layer 94 of R.T.V. silicon rubber of dural 40. The wall 17 of the supporting housing covers the entire assembly. FIG. 7 is an enlarged detailed sectional view taken from FIG. 6 and illustrates the pot member 18a. The slots 96 formed in the outer surface of the pot 18a contain the heater winding 20 as shown. The assembly thus has good heat conductive characteristics, as well as good characteristics for the transfer of ultrasonic energy from the crystal 18b into the container 19 to clean the lens.
FIG. 8 is an electrical schematic view of the driving oscillator 62. The oscillator is a flip-flop type which has the characteristic that it oscillates at the frequency of the crystal 18b, and continues to do so even when temperature changes cause the mechanical dimensions of the crystal to change so that the oscillator is self-tracking. Power is supplied to the oscillator through the pot heater 20 which serves additionally as a line voltage dropping resistor and a full wave rectifier 97 includes rectifying diodes D 1 , D 2 , D 3 , and D 4 which supply positive D.C. power to line 98 and negative D.C. power to line 99. A condenser C 1 is connected across the lines 99 and 98. The crystal 18b has one terminal connected to line 99 and its other terminal is connected to one side of transformer winding L 3 which has its other side connected to lead 101. A transistor T 2 has its emitter connected to line 99 and its collector to lead 101. The base of transistor T 2 is connected to line 98 through the resistor R 1 . Another transformer winding L 2 has one side connected to line 99 and its other side connected to a resistor R 4 and a capacitor C 3 which have their opposite side connected to the base of the transistor T 2 . A transistor T 1 has its emitter connected to line 98 and its collector connected to line 101, and its base is connected to the junction point between resistors R 2 and R 3 . The other side of resistor R 3 is connected to line 99. A capacitor C 2 is connected in parallel with resistor R 2 and a transformer winding L 1 is connected from line 98 to the junction point of resistor R 2 and a transformer winding L 1 is connected from line 98 to the junction point of resistor R 2 and capacitor C 2 .
The crystal 18b in combination with the transformer winding L 3 forms the frequency determining element of the oscillator 62, and thus as the dimensions of the crystal 18b change due to the large temperature variations frequency of the oscillator will track and stay matched to the crystal.
FIG. 9 illustrates a practical working embodiment which has been constructed according to this invention and illustrates the first and second timers 61 and 68, as well as the oscillator 62 and its various components mounted in hollow compartment within the base portion 16 which is supported on the heat conductive base 11. It is to be noted that the unit provides a compact and attractive cleaning unit which operates in an efficient and effective manner.
FIG. 10 illustrates a modification of the invention wherein the removable cleaning cup 21 of the prior embodiments has been replaced by a ceramic heating unit 112, which is formed with a central cup portion 113 and which is threaded at the top 114 so as to receive the threaded cap 23, and the lens holder. The cleaning fluid is directly placed into the cylindrical cup 112, which is formed with groove portions in which the heater element 116 is mounted and about which the crystal 117 extends. R.T.V. silicon rubber 118 surrounds the crystal 117 and the case 17 fits around the rubber 118. In this embodiment the entire unit is tipped to pour the cleaning fluid from the unit.
FIG. 13 illustrates a further earlier embodiment of the invention wherein a cylindrical ceramic member 121 is formed with a central opening 122 in which a mating lens container 123 can be received and which has a cap 124 to seal it. The lens, of course, are held within the container 123 by a lens holder which extends from the inside of the cap as illustrated for example in FIG. 11. A bail 126 is pivotally connected to the upper portion of the ceramic member 121 and is pivotable over the cap 124 of the container 123 to lock it tightly and sonically into the cleaning device. Heater coil 127 is wound about the ceramic member 121 in grooves formed therefore. A temperature sensor 128 is embedded in the ceramic member 121 at the bottom end of the container holder 123 and is provided with output leads 129 so as to utilize the output of the temperature sensor 128. The temperature sensor 128 controls the power supplied to the heating coil 127 electronically. An ultrasonic motor/transducer comprises a pair of discshaped piezoelectric crystals 131 and 132 which are separated by a thin center electrode 133 that might be made of aluminum, for example. an end washer 134 of steel or of other suitable material is mounted adjacent to crystal 131. A fiber washer 136 is mounted adjacent to the washer 134 and a flat washer 137 is mounted adjacent to the fiber washer 136. The output of the crystals 131 and 132 is coupled to the cleaning chamber by focusing vibrating front member 138, which might be made of magnesium for example, which engages the crystal 132 and has a curved end portion 139, which mates with the bottom of the ceramic member 121. The ceramic member and the focusing vibrating member 138 may be threadedly connected as shown. A bolt 141 extends through the member 138 to crystals 132, 131 and the related washers and carries a nut 142. An electrical terminal 143 is connected to the bolt 141 adjacent the nut 142 and a Scnoor washer 144 is mounted between the terminal 143 and the washer 137. In the embodiment of FIG. 13 the ultrasonic energy is applied from the bottom end of the ceramic pot 121 in a focused manner to the cleaning container 123 to clean the lenses in the lens holder.
The outer surface of the cup 21 is tapered and the inner surfaces of the ceramic member 18a and 121 are tapered so as to provide a tight fit thus assuring good thermal conduction between the heater and the liquid within the cup as well as assuring effective coupling of ultrasonic energy between the cylindrical or end driving crystals.
In operation the user plases the lens into the lens cover 42 and 52 and inserts them into the cleaning fluid within the cup 21 and places the cup into the cleaning machine. Switch 12 is closed and the cleaner automatically heats the cleaning fluid to the proper sterilizing temperature and then turns on the oscillator 62 which supplies high frequency ultrasonic energy at a high intensity which energy has free access to the lens due to the configuration of the holders 42 and 52. When the second timer 68 has timed out it turns off the entire machine and the cleaning sequence is completed and cup 21 may be removed, and the lenses put into immediate use. If desired the member 29 may be opened to allow liquid to be poured out of the cup through the openings 27 and 28 and/or rinse water applied to the cup.
Although the invention has been described with respect to preferred embodiments it is not to be so limited as changes and modifications may be made which are within the full scope as defined by the appended claims.
I claim:
1. Field of the Invention
This invention relates in general to apparatus for cleaning and rejuvenating contact lens of the hard and soft types, and in particular to an automatic lens cleaner.
2. Prior Art
The first use of lens dates back to antiquity in that lens were used by the ancient Romans and perhaps even by the Greeks. Fairly well refined lenses were fabricated as early as 1052 A.D., and Salvino l'Armato degli Armati constructed the first spectacles wearable on the nose in the year 1255 A.D.. Continuous progress has been made since that date, with new inventions and and discoveries in this field being put into almost immediate use. Some such developments were not always beneficial to the user.
Many different types of lenses for spectacles are used, and they are as varied as the defects in human vision. For example, such lens may be convex, bi-concave, concave-convex, segments of planes, cylinders and spheres. They may also be panascopic (dual) and periscopic (a divergent menicus lens). Much attention and development has resulted from the cosmetic or vanity aspects of spectacles, so as to render the wearer and/or the spectacles attractive. For example, spectacles of complicated and odd configurations have been constructed, many of which have been quite beautiful. Some such spectacles have been jeweled and have been very expensive.
Human vanity has probably led to the tremendous amount of work done in the United States and abroad on contact lenses. Such lens are directly placeable over and on the eyeball, thus, dispensing with all external signs of malvision since such lenses are not discernible by an observer. The exact date of the invention of contact lens has not been precisely resolved, and their discovery is claimed by inventors in several countries. About 1952 such lens were introduced in the United States with all of their unanticipated difficulties and concealed problems which were not obvious at that time. Even today many of the problems inherent with contact lenses are not generally recognized or understood.
One of the major problems resulting from the use of contact lens is that the insertion of any foreign body, no matter how small or sterile, into the eye will be treated by the living eye as a foreign body which will marshal the normal therapeutic, physiological reactive forces, so as to combat and to try to dislodge the intruder. Thus, the introduction of "hard" contact lenses created a need for a better understanding of the nature of the corneal edema problem and its solutions. Many articles and patents have appeared on this problem in, for example, the Journal of the American Pharmaceutical Association and the Journal of Ophthamology. Such literature illustrates that the problems of using contact lens of both the soft and hard type are many and complex.
Hard contact lens cannot be made of glass due to the danger of breakage and subsequent injury to the eyeball, but danger of methylmathacrylate plastic commonly known as "Plexiglas" in the United States or abroad as "Lucite." Hard lens are quite small, usually being in the range of 5 to 12 milimeters in diameter, are usually disc shaped and usually possess a concave-convex grind. As the art has advanced other types of shapes and more complex lens grinding has been attempted with some success. The advantage of using one of the many methylmethacrylate formulations for contact lens lies in their excellent optical refractive properties, which is of course a prime consideration in lens making, also in their durability and of most importance, for biological reasons, hygroscopic hygrosopic nature. Non-hygroscopic glass was ruled out for use in contact lens at a fairly early date. The disadvantages of plastic is that methylmethacrylate lens are easily scratched if handled carelessly or for example, if cleaned with mechanical rubbing or with abrasives. They are also easily damaged by the use of improper chemical cleaning agents, and if allowed to dry out when in storage will distort, sometimes irreversibly, and will become discolored or "fogged" and brittle. Also due to their hygroscopic nature and the environment in which they are used, body salts carried by the lachrymal fluids are concentrated in the lens, and if allowed to dry create deposits which can cause irritation and serious edema in the human eye when reused. Such deposits are very difficult to remove since they are embedded into the plastic and do not merely lie on its surface.
The problems associated with hard contact lens made it apparent at an early date that it would be desirable to develop a softer material. The less solid the material which is placed into the eye, the less is the haste of the biological rejection and in going from a solid to a less hard plastic to a soft plastic less difficulty in rejection by the eye is encountered. The ideal lens would be a liquid, however semi-liquid lens of a substance matching the soft living tissue, which is completely non-toxic in nature and to nature, would be highly desirable. Otto Wichterle of Czechoslovakia, who started on such an approach as early as 1963, has succeeded in fabricating soft lens using anyhydrous, sparingly cross-linked hydrophilic copolymers consisting of 98% by weight of water soluble monesters of a crylic or methacrylic acids. Such lens when dehydrated are hard enough to work and can be cut, ground and polished. When these lens are exposed to water, they swell to a predeterminable shape of precise size and become exceedingly soft and "skin-like" while maintaining their optical transparency and their refractory characteristics.
Such gelatinous soft lenses, being extremely hygroscopic, have previously had to be kept in a sterile liquid solution at all times. They must also be very carefully handled, and due to their "culture" nature must be preserved from bacterial and viral contamination. Such lenses in their nascent state are called "Xerogels" by Wichterle and "Hydrogels" after they have been swelled to their final size. Being highly porous, i.e., osmotic membranes, the interpenetration of impurities and natural body salts are severe and are even more difficult to remove. Such lens are very expensive and the above problems have resulted in such lens being utilizable for only a short lifetime before they become unusable and must be replaced.
Both the hard and soft type lenses are plastic and therefore are easily scratched or damaged, thus making cleaning by direct handling difficult. Both types of lens are hygroscopic and permit interpenetration of undesirable body salts and poisons, and invasion by microbes and viri, thereby making sterilization necessary, but extremely difficult. Also both types of lenses if permitted to dry out become damaged, distorted, discolored, or contaminated beyond acceptable or safe use.
Various devices and methods have been used in the past to try to clean hard and soft lenses. One approach, for example, is to keep the lens submerged in sterile water at all times when not in the eye. Various jets and plungers have been used to agitate the liquid cleaning solutions in which the lens are immersed. Another approach is one which stores the lens in a carrying case which is then subjected to the pressure of local tap water or to overnight soaking and rinsing by hand. Several writers on the prior art have indiscriminately recommended the use of detergent soaps and medical germicidal solutions for cleaning and soaking. However, such cleaners, which may be excellent for pots and pans, can be highly dangerous for use in cleaning contact lenses because the lens pick up and retain in their pores part of the detergent and medical germicidal chemicals. Such materials can be very dangerous to the human eye when they are leached out of the interior surface of the lens by the lachymal fluid onto the eyeball. Such cleaning chemicals quite probably have caused many of the numerous documented cases of infection, edema, and serious eye damage to contact lens users.
Hard methylmethacrylate lens cause much discomfort due to the hydrophilic nature of their surface and complaints of fogging and irritation have been common. Even though the plastic is capable of hydration, it will not readily do so and many surfactants are ineffective. As stated by Bancroft in the Journal of Physical Chemistry 1913, the interfacial tensions between a solid and a liquid, for example, are lowered by the formation of a molecular film which contains a mixture of the molecules from the surfactant and from the two materials, which in the case of lenses is methylmethacrylate and water. This surfactant film has two interfacial tensions, one with the water and one with the plastic. Depending solely on the ionic potential present, the hydrophilic portion may attach itself to the methylmethacrylate plastic or onto the water. If the hydrophilic surface is attached to the plastic, then a new outer surface is formed which will act to repel (hydrophobic) water and any water soluble chemicals in the solution. If such an event takes place, no cleaning will be effected and ocmplete sterilization can not take place and the viri and microbes will become entrapped in the interior of the lenses.
Attempts have been made to solve this problem by the use of proper ionic wetting solutions which were slightly hypertonic in nature, and exhibited the desirable characteristics. Many contact lens wearers develop mild or severe edema of the corneal epithelium which is believed to be caused by the drying out of the surface directly behind the lenses. However, recent research, including my observations, have shown that this damage is caused by chemical irritants as well as by mechanical irritation. Such chemical irritants not only may not be removed during the cleaning process, but may actually be supplied to the lens from the cleaning fluid during the cleaning process. I have discovered that the approaches utilized by the prior art have not fully understood the nature of the problem and its answer which is the providing of super-cleaning including deep inside the interstial porous cavities in a manner and with cleaning solutions which are completely safe and non-irritant.
SUMMARY OF THE INVENTION
The present invention relates to a method and apparatus for the deep cleaning of lens of various sorts. Although the use of ultrasonic energy for cleaning of lenses has been suggested, the successful application of ultrasound to cleaning hard and soft lens has not been accomplished prior to my invention. I have discovered after exhaustive tests and measurements that it is the porous, hygroscopic nature of the lens themselves, which make it necessary to utilize a great deal of physical and chemical knowledge to obtain the superior cleaning of my invention. Low frequency ultrasound commonly used in industrial cleaners such as a frequency of 20kHz failed to cause penetration of the fluids into the membranes of the lens, and I have discovered that it is necessary to use a higher frequency such as 40 to 100 kHz to accomplish effective deep cleaning.
In addition I have discovered that the intensity level of the ultrasonic energy required for penetration was far greater than what would normally be considered as needed for such small items as contact lens. I have discovered that intensities in the order of 10-20 watts per square centimeter are required. This level is an emulsifying, molecular bond-breaking level of sonic energy, but such an energy level is needed to truly interpenetrate the interstial regions of the lens for deep cleaning. Lower energy levels or lower frequencies cannot accomplish the thoroughly cleaning and rejuvenation of the lens as does the methods and apparatus of my invention.
In summary then: two cleaning phenomena must occur; one is the intense cavitation of ultrasonic emulsification and the other is the high liquid temperatures approved for medical sterilization of objects wherein it has proved necessary to elevate the liquid solutions used to 170° to 200° F. Such temperatures tend to prevent cavitation and mistune the ultrasonic cleaning generator drive system, which are additional problems solved by my invention.
Finally, my invention encompasses the proper, high temperature germicidal ingredients, surfactants, and surface tension increasers in the cavitating cleaning fluid. This fluid must have a high osmotic pressure, must readily cavitate and must permit ultrasonic energy to easily flow through the fluid as well as through the membraneous porosity of the hard and soft lens at temperatures of 170° to 200° F. This is especially true for the soft lens.
Problems associated with meeting all of these complex requirements make it difficult to design a device and to obtain a fluid which finally results in a super-cleaning (including the interior) of the lens that is completely safe and comfortable for the user, and which will provide a lens lifetime many times that of lens cleaned and used under present methods.
During the course of my research it was found possible to contaminate lens with extremely small particle sized radioactive molybdenum which penetrated through the porous methylmethacrylate material. This penetration phenomenon also appears even more pronouncedly in the soft lens and when they were dried it was readily perceived. The heaviest of contamination, using the smallest molecular cross-sectional materials, was tried using even viri size contaminants. Also all sorts of normal contaminants such as lipstick, other make-up, dirt and dried-on body salts of all types were used. In every case, normal cleaning as recommended by the various pharmaceutical houses and lens makers cleaned only partially while the devices and chemicals used in my invention completely succeeded.
One unexpected result which was entirely unforeseen, was the rejuvenation and reconstitution of the copolymer soft lens wherein they could be dired out and reconstituted tens of times without damage to their structures or dimensions. This is in contrast to present methods of cleaning wherein when these lens are once dried out they lose their usefulness, change dimensions, discolor, warp and frequently must be discarded. The application of intense ultrasound in the present invention reconstitutes the copolymeric purity and molecular structure of the lens for reasons not entirely understood, and old dried out lens treated by the apparatus in methods of the invention resulted in clear, fog-free lenses with no discoloration and a return to the skin-like texture that is well known to be desirable. All brittleness, fragilibility and contamination was removed in 1 to 2 minutes application of the heat, chemicals and high intensity ultrasound of the invention.
It is an object of the present invention to clean ocular and other types of lenses, of the hard type and of the soft, tissue-like types.
Another object of the invention is to sterilize lenses of all bacteria, fungi and viri.
Still another object of the invention is to clean, sterilize and reconstitute the membraneous materials of the lens deep in the pores and throughout the pore structure.
Another object of the invention is to provide an automatic cleaning machine for lens.
Yet, another object that is provided is ease of user storage and simplified transporting apparatus for lens.
Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure and in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1, is an exploded perspective view of the invention,
FIG. 2, is a partial cutaway view of the invention,
FIG. 3, is an electrical schematic of the invention,
FIG. 4, illustrates the operation of the cylindrical sonic energizer of the invention,
FIG. 5, is a plot of pressure v. distance from the axis response of a cylindrical driving crystal radially polarized,
FIG. 6, is a sectional view illustrating construction of the pot heater ultrasonic actuator and thermal cutout,
FIG. 7, is a detailed sectional view illustrating the bonding and insulation,
FIG. 8, is an electrical schematic of the self-tuning electronic driving generator,
FIG. 9, is a sectional view of the cleaner with the lens holder and lens in place,
FIG. 10, is a sectional view of a one piece modification of the invention,
FIG. 11, is an enlarged perspective view of the cap and double trap door cleaning cage in which the lens are placed,
FIG. 12, is a detailed exterior view of the cap and;
FIG. 13, is a sectional view of a modification of the invention using an end driven ultrasonic motor.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates the cleaner of this invention which comprises a base member 11 which has an on-off switch 12 and a power cord 13, and a "cleaning-ready" indicator light 14. A hollow cylindrical support member 16 extends upwardly from the base 11 and supports a heating and driving cylindrical pot 18 and an outer cover 17. Lens cup 19 has a tapered cylindrical portion 21 which mates with the inner diameter of the heater and driver 18, and has an upper portion 22 which is threaded so as to threadedly receive the lens cap holder 23, which includes the cap 24 which is internally threaded to mate with the threads 22, and which has pivoted lens holders 42 and 52, which are pivotally attached to the center partition member 37 of the cap 23. The cap structure is best shown in FIGS. 11 and 12 and let it be noted that the inside portion of the cap 23 is threaded as shown by numeral 36, and has a hand portion 26. The center partition 37 is connected by the extension 38 to the inside of the cap 23, and has a first lens holder 42 pivotally attached by the hinges 43 and 44 to the portion 37. A spring clip 46 engages a notch 47 of the number 37 to lock the holder in the closed position. A center portion of the holder 42 is formed with openings defined by spokes 48 and 49, which form an enclosing cage in which the lens 51 may be placed. The partition 37 is formed with openings between the spokes 39 and 41 as shown in FIG. 11. The second holder 52 is similar to the holder 42 and the second lens is receivable therein.
As shown in FIG. 12 the handle portion 26 of the cap 24 may be formed with a T-shaped slot 25 in which is received a mating T-shaped member 29, which has a vertical portion 31 and a horizontal portion 32. A pair of openings 27 and 28 are formed in the cap 24 and mate with slots formed in the T-shaped member 29 when it's moved to a certain position so that rinsing water or cleaning fluid may be poured into the opening 28 through the slot 34 into the lens container and flow out through the associated slot and opening 27. A detent 33 is formed in the member 29 to hold it in a preset position.
FIG. 2 is a cutaway view of the bearer and drive unit with the lens cup 19 and cap 23 mounted therein. The heater and driver 18 comprises an inner cylindrical member 18a, made of ceramic or high temperature epoxy, which has embedded in it a heater 20 that might be made of chromal V heating element of approximately 130-200 ohms. Surrounding the inner cylindrical member 18a is radially polarized piezoelectric crystal 18b of generally cylindrical shape which is tightly bonded to the cylindrical holding/heater unit 18a.
The crystal is in turn embedded in a cylindrical holder 17 which might be of a room temperature vulcanizing elastomer of durometer 20 to 70 units.
The oscillator drive unit 62 is connected by leads 63 and 64 to the crystal 18b. Thermal cutout 25 is connected to the heater 20 and to the 80 second timer 61 by leads 66 and 67. The timer 61 is connected to the oscillator 62 and to a 3 minute timer 68 which is connected by the power cord 13 to a power plug 69 to supply power to the unit.
The actual electrical schematic is shown in FIG. 3, wherein the power plug 69 is connected to a first lead 71 which is connected to the on-off switch 12 and to a fuse 72. The other power lead 73 is connected to a heater element of the 3 minute timer 68. The other side of the heater element 68 is connected to the fuse 72 by lead 74. A pair of normally closed contacts 76 and 77 are opened by the heater 68 after a preset time, as for example, 3 minutes, so as to turn the cleaner off. Contact 76 is connected to lead 74 and contact 77 is connected to the oscillator 62 and to the "cleaning-ready" light 14 which has its opposite side connected to lead 73. The other lead to oscillator 62 is designated 79 and is connected to normally open contact 81 which mates with contact 82 which is connected to lead 83. The 80 second timer 61 has a resistive element which has one side connected to lead 74 and the other side is connected to lead 73. Lead 83 is connected to one end 84 of the pot heater winding 20 and the other end 86 of the pot heater winding is connected to lead 73. The thermal cutout 25 includes a pair of normally closed contacts 87 and 88. Contact 87 is connected to lead 83 and contact 88 is connected to lead 78.
The cleaner operates as follows:
When the on-off switch 12 is closed power will be applied to the heater 61 and the heater 68 simultaneously starting their counting cycle. Power will also be supplied to the pot heating element 20 through lead 73 and normally closed contacts 76 and 77, and through contact 87 and 88 of the thermal cutout unit 25. This will cause the cleaning fluid inside the cup 19 to be brought up to a temperature of 170° F. in approximately 75 seconds. At this time the contact 87 and 88 open which disconnects power from the pot heater 20. The cleaning fluid in the pot 19 will continue to rise to approximately 194° F. during the next 5 seconds at which time thermal delay relay 61 closes contacts 81 and 82 to apply A.C. line voltage to the ultrasonic oscillator 62 input terminals, through pot heater element 20, and sonic energy will be supplied to drive the crystal 18b from the oscillator 62. The 3 minute thermal timer 68 disconnects power completely from the heater as well as the oscillator by opening contact 76 and 77 and indicator light 14 goes out indicating cycle is over.
FIG. 4 illustrates the radially polarized piezoelectric vibrating element 18b which when excited through leads 63 and 64 by oscillator 62, supplies sonic energy into the interior of the cleaning cup 19. FIG. 5 illustrates the high sonic pressure generated in the cleaning cup 19 plotted as a function of distance from the center axis of the cup. It is to be noted that the cleaning pressure is maximum near the center axis of the cleaning cup where the lens are disposed.
FIG. 6 is a more detailed sectional view of an actual working model constructed and operated. The ceramic pot 18a has embedded in its outside wall the heating coil 20 of about 150 ohms. The pot 18a is then bonded to the cylindrical crystal drive element 18b by high temperature epoxy 91, which is capable of withstanding 700°-800° F.. Alternatively, the bonding may be accomplished by a ceramic cement. Also portions of the heater winding 20 may be embedded in the base 92 of the pot 18a to provide temperature anticipation sensing. This portion of the heater element is designated 93 in FIG. 6. The crystal 18b and pot 18a are surrounded by a relatively soft layer 94 of R.T.V. silicon rubber of dural 40. The wall 17 of the supporting housing covers the entire assembly. FIG. 7 is an enlarged detailed sectional view taken from FIG. 6 and illustrates the pot member 18a. The slots 96 formed in the outer surface of the pot 18a contain the heater winding 20 as shown. The assembly thus has good heat conductive characteristics, as well as good characteristics for the transfer of ultrasonic energy from the crystal 18b into the container 19 to clean the lens.
FIG. 8 is an electrical schematic view of the driving oscillator 62. The oscillator is a flip-flop type which has the characteristic that it oscillates at the frequency of the crystal 18b, and continues to do so even when temperature changes cause the mechanical dimensions of the crystal to change so that the oscillator is self-tracking. Power is supplied to the oscillator through the pot heater 20 which serves additionally as a line voltage dropping resistor and a full wave rectifier 97 includes rectifying diodes D 1 , D 2 , D 3 , and D 4 which supply positive D.C. power to line 98 and negative D.C. power to line 99. A condenser C 1 is connected across the lines 99 and 98. The crystal 18b has one terminal connected to line 99 and its other terminal is connected to one side of transformer winding L 3 which has its other side connected to lead 101. A transistor T 2 has its emitter connected to line 99 and its collector to lead 101. The base of transistor T 2 is connected to line 98 through the resistor R 1 . Another transformer winding L 2 has one side connected to line 99 and its other side connected to a resistor R 4 and a capacitor C 3 which have their opposite side connected to the base of the transistor T 2 . A transistor T 1 has its emitter connected to line 98 and its collector connected to line 101, and its base is connected to the junction point between resistors R 2 and R 3 . The other side of resistor R 3 is connected to line 99. A capacitor C 2 is connected in parallel with resistor R 2 and a transformer winding L 1 is connected from line 98 to the junction point of resistor R 2 and a transformer winding L 1 is connected from line 98 to the junction point of resistor R 2 and capacitor C 2 .
The crystal 18b in combination with the transformer winding L 3 forms the frequency determining element of the oscillator 62, and thus as the dimensions of the crystal 18b change due to the large temperature variations frequency of the oscillator will track and stay matched to the crystal.
FIG. 9 illustrates a practical working embodiment which has been constructed according to this invention and illustrates the first and second timers 61 and 68, as well as the oscillator 62 and its various components mounted in hollow compartment within the base portion 16 which is supported on the heat conductive base 11. It is to be noted that the unit provides a compact and attractive cleaning unit which operates in an efficient and effective manner.
FIG. 10 illustrates a modification of the invention wherein the removable cleaning cup 21 of the prior embodiments has been replaced by a ceramic heating unit 112, which is formed with a central cup portion 113 and which is threaded at the top 114 so as to receive the threaded cap 23, and the lens holder. The cleaning fluid is directly placed into the cylindrical cup 112, which is formed with groove portions in which the heater element 116 is mounted and about which the crystal 117 extends. R.T.V. silicon rubber 118 surrounds the crystal 117 and the case 17 fits around the rubber 118. In this embodiment the entire unit is tipped to pour the cleaning fluid from the unit.
FIG. 13 illustrates a further earlier embodiment of the invention wherein a cylindrical ceramic member 121 is formed with a central opening 122 in which a mating lens container 123 can be received and which has a cap 124 to seal it. The lens, of course, are held within the container 123 by a lens holder which extends from the inside of the cap as illustrated for example in FIG. 11. A bail 126 is pivotally connected to the upper portion of the ceramic member 121 and is pivotable over the cap 124 of the container 123 to lock it tightly and sonically into the cleaning device. Heater coil 127 is wound about the ceramic member 121 in grooves formed therefore. A temperature sensor 128 is embedded in the ceramic member 121 at the bottom end of the container holder 123 and is provided with output leads 129 so as to utilize the output of the temperature sensor 128. The temperature sensor 128 controls the power supplied to the heating coil 127 electronically. An ultrasonic motor/transducer comprises a pair of discshaped piezoelectric crystals 131 and 132 which are separated by a thin center electrode 133 that might be made of aluminum, for example. an end washer 134 of steel or of other suitable material is mounted adjacent to crystal 131. A fiber washer 136 is mounted adjacent to the washer 134 and a flat washer 137 is mounted adjacent to the fiber washer 136. The output of the crystals 131 and 132 is coupled to the cleaning chamber by focusing vibrating front member 138, which might be made of magnesium for example, which engages the crystal 132 and has a curved end portion 139, which mates with the bottom of the ceramic member 121. The ceramic member and the focusing vibrating member 138 may be threadedly connected as shown. A bolt 141 extends through the member 138 to crystals 132, 131 and the related washers and carries a nut 142. An electrical terminal 143 is connected to the bolt 141 adjacent the nut 142 and a Scnoor washer 144 is mounted between the terminal 143 and the washer 137. In the embodiment of FIG. 13 the ultrasonic energy is applied from the bottom end of the ceramic pot 121 in a focused manner to the cleaning container 123 to clean the lenses in the lens holder.
The outer surface of the cup 21 is tapered and the inner surfaces of the ceramic member 18a and 121 are tapered so as to provide a tight fit thus assuring good thermal conduction between the heater and the liquid within the cup as well as assuring effective coupling of ultrasonic energy between the cylindrical or end driving crystals.
In operation the user plases the lens into the lens cover 42 and 52 and inserts them into the cleaning fluid within the cup 21 and places the cup into the cleaning machine. Switch 12 is closed and the cleaner automatically heats the cleaning fluid to the proper sterilizing temperature and then turns on the oscillator 62 which supplies high frequency ultrasonic energy at a high intensity which energy has free access to the lens due to the configuration of the holders 42 and 52. When the second timer 68 has timed out it turns off the entire machine and the cleaning sequence is completed and cup 21 may be removed, and the lenses put into immediate use. If desired the member 29 may be opened to allow liquid to be poured out of the cup through the openings 27 and 28 and/or rinse water applied to the cup.
Although the invention has been described with respect to preferred embodiments it is not to be so limited as changes and modifications may be made which are within the full scope as defined by the appended claims.
I claim: