Rigid polyurethane or polyisocyanurate foams are produced by reacting an organic polyisocyanate with an amine-based polyether polyol in the presence of a catalyst, a hydrogen-containing fluorocarbon, water and carbon dioxide.

The present invention relates to a process for the production of rigid polyurethane or polyisocyanurate foams in which an HFC (hydrogen-containing fluorocarbon) is used in combination with an added amount of carbon dioxide.
Processes for the production of rigid polyurethane foams are known. See, for example, U.S. Pat. Nos. 3,085,085; 3,153,002; 3,222,357; and 4,430,490.
At the present time, a major concern of foam producers, particularly rigid foam producers, is the development of rigid foam systems in which the ozone depleting chlorofluorocarbon (xe2x80x9cCFCxe2x80x9d) or hydrochlorofluorocarbon (xe2x80x9cHCFCxe2x80x9d) blowing agent is replaced with a more environmentally acceptable blowing agent. HFCs (hydrogen containing fluorocarbons), and hydrocarbons such as n-pentane, cyclopentane, isopentane and blends of these blowing agents are presently considered to be possible alternatives.
U.S. Pat. No. 4,900,365, for example, teaches that a mixture of trichlorofluoromethane, a dichlorofluoroethane selected from a specified group and isopentane is useful as a blowing agent for the preparation of polyurethane foams. Dishart et al""s paper entitled xe2x80x9cThe DuPont Program on Fluorocarbon Alternative Blowing Agents for Polyurethane Foamsxe2x80x9d, Polyurethanes World Congress 1987, pages 59-66 discusses the investigation of various HCFCs as possible blowing agents for rigid polyurethane foams. Neither of these disclosures, however, teaches a process for the production of rigid polyurethane foams having good physical properties from polyols with an HFC blowing agent.
U.S. Pat. No. 4,972,002 discloses a process for the production of cellular plastics in which an emulsion is used. A low boiling fluorinated or perfluorinated hydrocarbon or sulfur hexafluoride is emulsified in one of the starting materials (i.e., the isocyanate, polyol, etc.) from which the foam is to be produced
U.S. Pat. No. 5,169,873 discloses a process for the production of foams in which the blowing agent is a mixture of at least one fluoroalkane corresponding to a specified formula and at least one fluorinated ether corresponding to a specified formula.
U.S. Pat. No. 5,164,419 discloses a process for the production of polyurethane foams in which 1,1-difluoroethane in combination with a minimum amount of water is used as the blowing agent. However, the only foam described in this disclosure had a high k-factor of 0.18 BTU-in/hr-ft2-xc2x0 F.
U.S. Pat. No. 5,164,418 discloses a process for producing isocyanate-based foams in which the blowing agent is at least 10 mol % of a fluoroalkane. Mixtures of a fluoroalkane and significant amounts of water (i.e., greater than 20%) are exemplified.
U.S. Pat. No. 4,931,482 discloses the use of 1,1,1,4,4,4-hexafluorobutane as a blowing agent to produce isocyanate-based foams such as polyurethane and polyisocyanurate foams. The disclosed foams are made by reacting an isocyanate with any of the known isocyanate-reactive compounds. Water and other known blowing agents may optionally be used in combination with the required 1,1,1,4,4,4-hexafluorobutane blowing agent. The k-factors for foams produced using the hexafluorobutane blowing agent are not, however, reported.
Even though the use of HFC""s may offer the best solution to the appliance industry as an alternative to the use of HCFC""s, the costs of such HFC""s are expected to be higher than the use of HCFC""s. Therefore, means of reducing the levels of HFC""s are desired. One way of reducing levels of HFC""s is to use water to generate carbon dioxide as a blowing agent in the foam formulation.
U.S. Pat. No. 5,461,084 discloses a process for the production of rigid polyurethane foams produced by reacting an amine, an organic polyisocyanate, an HFC, and also an amount of water.
However, this is undesirable in an industry where the use of increased amounts of water will likely increase the thermal conductivity.
Therefore, a process in which a polyol and water could be used in combination with the more environmentally acceptable HFC blowing agents to produce a rigid polyurethane foam having good physical properties, including low k-factor, would be advantageous.
It is an object of the present invention to provide a process for the production of rigid polyurethane foams in which an HFC in combination with an amount of water and also added carbon dioxide is used as the blowing agent.
It is a further object of the present invention to provide a process for the production of rigid polyurethane foams which are useful in the production of refrigeration units.
These and other objects which will be apparent to those skilled in the art are accomplished by reacting an organic polyisocyanate with an amine-initiated polyether polyol having an average molecular weight of at least about 149, preferably from about 149 to about 1500, in the presence of a hydrogen-containing fluorocarbon, a minor amount of water, carbon dioxide, surfactant and a catalyst. Isocyanate-reactive compounds which are not amine-initiated may optionally be included in the reaction mixture in an amount of up to 70% by weight, based on the total amount of isocyanate-reactive materials.
The present invention is directed to a process for the production of rigid polyurethane foams or polyisocyanurate foams and to the foams produced by this process. In the process of the present invention, (a) an organic isocyanate is reacted with (b) an amine-based polyether polyol having an average molecular weight of at least about 149, preferably from about 149 to about 1500, and an epoxide content of from about 65 to about 98% by weight, preferably from about 75 to about 98% by weight based on the total weight of the amine initiator plus the epoxide, in the presence of (c) a blowing agent made up of (1) at least one hydrogen-containing fluorocarbon and (2) an amount of water and (3) an added amount of carbon dioxide and (d) a catalyst, and (e) at least one surfactant, at an isocyanate index of from about 0.9 to about 3.0, preferably from about 1.00 to about 1.50. The product foams generally have k-factors ranging from about 0.120 BTU-in./hr.ft2xc2x0 F. to 0.160 BTU-in./hr.ft2xc2x0 F. at 75xc2x0 F.
Any of the known organic isocyanates, modified isocyanates or isocyanate-terminated prepolymers made from any of the known organic isocyanates may be used in the practice of the present invention. Suitable isocyanates include aromatic, aliphatic, and cycloaliphatic polyisocyanates and combinations thereof. Useful isocyanates include: diisocyanates such as m-phenylene diisocyanate, p-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,6-hexamethylene diisocyanate, 1,4-hexamethylene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, hexahydro-toluene diisocyanate and its isomers, isophorone diisocyanate, dicyclo-hexylmethane diisocyanates, 1,5-naphthylene diisocyanate, 4,4xe2x80x2-diphenylmethane diisocyanate, 2,4xe2x80x2-diphenylmethane diisocyanate, 4,4xe2x80x2-biphenylene diisocyanate, 3,3xe2x80x2-dimethoxy-4,4xe2x80x2-biphenylene diisocyanate and 3,3xe2x80x2-dimethyl-diphenylpropane-4,4xe2x80x2-diisocyanate; triisocyanates such as 2,4,6-toluene triisocyanate; and polyisocyanates such as 4,4xe2x80x2-dimethyl-diphenylmethane-2,2xe2x80x2,5,5xe2x80x2-tetraisocyanate and the polymethylene polyphenylpolyisocyanates.
Undistilled or a crude polyisocyanate may also be used in making polyurethanes by the process of the present invention. The crude toluene diisocyanate obtained by phosgenating a mixture of toluene diamines and the crude diphenylmethane diisocyanate obtained by phosgenating crude diphenylmethanediamine (polymeric MDI) are examples of suitable crude polyisocyanates. Suitable undistilled or crude polyisocyanates are disclosed in U.S. Pat. No. 3,215,652.
Modified isocyanates are obtained by chemical reaction of diisocyanates and/or polyisocyanates. Modified isocyanates useful in the practice of the present invention include isocyanates containing ester groups, urea groups, biuret groups, allophanate groups, carbodiimide groups, isocyanurate groups, uretdione groups and/or urethane groups. Preferred examples of modified isocyanate include prepolymers containing NCO groups and having an NCO content of from about 25 to about 35 wt %, preferably from about 28 to about 32 wt %, particularly those based on polyether polyols or polyester polyols and diphenylmethane diisocyanate. Processes for the production of these prepolymers are known in the art.
The most preferred polyisocyanates for the production of rigid polyurethanes in accordance with the present invention are methylene-bridged polyphenyl polyisocyanates and prepolymers of methylene-bridged polyphenyl polyisocyanates having an average functionality of from about 1.8 to about 3.5 (preferably from about 2.0 to about 3.1) isocyanate moieties per molecule and an NCO content of from about 25 to about 34% by weight, due to their ability to cross-link the polyurethane.
The polyisocyanate is generally used in an amount such that the isocyanate index (i.e., the ratio of equivalents of isocyanate groups to equivalents of isocyanate-reactive groups) is from about 0.9 to about 3.0, preferably from about 1.0 to about 1.5.
The polyols employed in the process of the present invention are amine-initiated polyether polyols having functionalities of from about 3 to about 5 and molecular weights of at least about 149, preferably from about 149 to about 1500, most preferably from about 300 to about 800. These amine-based polyols are prepared by reacting an amine, polyamine or aminoalcohol and optionally other initiators (with or without water) with propylene oxide and optionally, ethylene oxide, and also optionally, in the presence of an alkaline catalyst. If an alkaline catalyst is utilized, the removal or neturalization of the catalyst can be by the treatment of the product with an acid, preferably a hydroxy-carboxylic acid so as to neutralize the alkaline catalyst, extraction of the catalyst, or the use of ion exchange resins. Such processes are described in U.S. Pat. No. 5,962,749. U.S. Pat. Nos. 2,697,118 and 6,004,482 disclose a suitable process for the production of such amine-initiated polyols.
Examples of suitable amine initiators include: ammonia, ethylene diamine, diethylene triamine, hexamethylene diamine and aromatic amines such as toluene diamine, and aminoalcohols. The preferred initiator is toluene diamine.
It is preferred that the amine initiator be reacted with propylene oxide, or ethylene oxide, followed by propylene oxide. If used, the ethylene oxide may be used in an amount up to 60% by weight of the total alkylene oxide used. The propylene oxide is generally used in an amount of from about 40 to about 100% by weight of the total alkylene oxide employed, preferably from about 60 to about 100% by weight. The total amount of alkylene oxide used is selected so that the product polyol will have an average molecular weight of at least about 149, preferably from about 149 to about 1500.
The amine-based polyether polyol is included in the foam-forming mixture in an amount of from about 10 to 70% by weight, based on the total foam-forming mixture, preferably from about 15 to about 50% by weight.
Other polyether polyols (i.e., polyether polyols which are not based on an amine) known to be useful in the production of rigid polyurethane foams as well as polyester polyols may, optionally, be used in combination with the required amine-based polyether polyol. When used, these optional polyols are present in an amount which is no greater than 70%, preferably from about 20 to about 50% of the total amount of polyol.
The HFC blowing agent employed in the process of the present invention may be any of the known hydrogen-containing fluorocarbons having three to five carbons. Specific examples of such blowing agents include: 1,1,1,4,4,4-hexafluorobutane (HFC-356); the pentafluoropropanes such as 1,1,2,2,3-pentafluoropropane (HFC-245ca), 1,1,2,3,3-pentafluoropropane (HFC-245ea), 1,1,1,2,3-pentafluoropropane (HFC-245eb), and 1,1,1,3,3-pentafluoropropane (HFC-245fa); the hexafluoropropanes such as 1,1,2,2,3,3-hexafluoropropane (HFC-236ca), 1,1,1,2,2,3-hexafluoropropane (HFC-236cb), 1,1,1,2,3,3-hexafluoropropane (HFC-236ea), 1,1,1,3,3,3-hexafluoropropane (HFC-236fa); and the pentafluorobutanes such as 1,1,1,3,3-pentafluorobutane (HFC-365). HFC-245fa is preferred. The blowing agent is generally included in the foam-forming mixture in an amount of from about 3 to about 20% by weight, based on the total foam formulation, preferably from about 5 to about 16% by weight.
Water is also included in the reaction mixtures of the present invention. As used herein, water in an amount of up to about 5.0%, preferably from about 0.1% to about 3.0%, most preferably from about 0.2 to about 2.0%, based on the total foam formulation is included in the reaction mixture.
Carbon dioxide is also included in the reaction mixtures of the present invention. As used herein, carbon dioxide in an amount of up to about 5.0%, and preferably from about 0.5 to 2.5% based on the total foam formulation is included in the reaction mixture
Any of the catalysts known to be useful in the production of rigid polyurethane foams may be employed in the process of the present invention. Tertiary amine catalysts are particularly preferred. Specific examples of suitable catalysts include: pentamethyldiethylenetriamine, N,N-dimethylcyclohexylamine, N,Nxe2x80x2,Nxe2x80x3-dimethylamino-propylhexahydrotriazine, tetramethylethylenediamine, tetramethylbutylene diamine and dimethylethanolamine. Pentamethyldiethylenetriamine, N,Nxe2x80x2,Nxe2x80x3-dimethylamino-propylhexahydrotriazine, and N,N-dimethylcyclohexyl-amine are particularly preferred.
Materials which may optionally be included in the foam-forming mixtures of the present invention include: chain extenders, crosslinking agents, surfactants, pigments, colorants, fillers, antioxidants, flame retardants, and stabilizers. Surfactants are a preferred additive.
The isocyanate and isocyanate-reactive materials are used in quantities such that the equivalent ratio of isocyanate groups to isocyanate-reactive groups is from about 0.9 to about 3.0, preferably from about 1.0 to about 1.5.
Having thus described our invention, the following examples are given as being illustrative thereof. All parts and percentages given in these examples are parts by weight and percentages by weight, unless otherwise indicated.

Polyurethane or polyisocyanurate foams blown with hydrofluorocarbons and carbon atoms


Structure-based processing includes a method of diagnosing diseases that works by arranging diseases, symptoms, and questions into a set of related disease, symptom, and question structures, such as objects or lists, in such a way that the structures can be processed to generate a dialogue with a patient. A structure-based processing system organizes medical knowledge into formal structures and then executes those structures on a structure engine to automatically select the next question. Patient responses to the questions lead to more questions and ultimately to a diagnosis.

1. Field of the Invention
The field of the invention relates to computerized medical diagnostic systems. More particularly, embodiments of the present invention relate to a computerized system for time-based diagnosis of a patient's medical complaint.
2. Description of the Related Technology
Health care costs currently represent a significant portion of the United States Gross National Product and are generally rising faster than any other component of the Consumer Price Index. Moreover, usually because of an inability to pay for medical services, many people are deprived of access to even the most basic medical care and information.
Many people delay in obtaining, or are prevented from seeking, medical attention because of cost, time constraints, or inconvenience. If the public had universal, unrestricted, and easy access to medical information, many diseases could be prevented. Likewise, the early detection and treatment of numerous diseases could keep many patients from reaching the advanced stages of illness, the treatment of which is a significant part of the financial burden attributed to our nation's health care system. It is clear that the United States is facing health-related issues of enormous proportions and that present solutions are not robust.
Previous attempts at tackling the healthcare problem have involved various forms of automation. Some of these attempts have been in the form of a dial-in library of answers to medical questions. Other attempts have targeted providing doctors with computerized aids for use during a patient examination. These methods involve static procedures or algorithms. What is desired is an automated way of providing to a patient medical advice and diagnosis that is quick, efficient and accurate. Such a medical advice system should be modular to allow expansion for new types of medical problems or methods of detection.

This patent is subject to a terminal disclaimer.


A removable automobile vehicle seat with a tilting seat pan has at least one mechanism for connecting the front of the seat to the floor of the vehicle. The mechanism has an anchoring foot including a device for positioning the foot on an anchoring part that is joined to the floor. A lock pivots on the foot to engage with the anchoring part in a locking position such that the foot is immobilized on the floor. A lug connects a frame of the seat pan with the foot, the connecting lug being joined to the seat pan frame and mounted on the foot to pivot around a transverse axis. This allows the seat pan to pivot between a horizontal normal utilization position and a tilted forward position.

This invention concerns a removable automobile seat with a tilting seat pan. It concerns more specifically a mechanism for joining the front of such a seat to the floor of an automobile vehicle.
Removable seats are generally designed so that they can be fixed to the floor of the vehicle in a removable manner, and therefore with the greatest possible ease of installation and removal, but also with the highest possible level of security regarding their anchoring to the floor. The means of fixing these seats to the floor must therefore be easy to use but also guarantee reliable and strong anchoring to the floor.
Moreover, a common goal is also to be able to fold these seats when not in use to increase the available floor space. It is known to this end to have folding and tilting seats, where first the seat back can be folded down onto the seat pan, and then the entire seat assembly tilted and raised forwards, in a position we will call the xe2x80x9cstowedxe2x80x9d position, by pivoting around a transverse axis situated towards the front of the seat pan. The seat must be able to be maintained in this raised position without any risk of falling accidentally rearwards by pivoting in the opposite direction, which is ensured in certain vehicles by an attaching system, such as elastic luggage cables (of the Sandow(copyright) type), joining the raised seat to another seat located in front of it, or to any other fixed element of the vehicle. This type of attaching system is not very satisfactory however, because it requires performing additional actions to attach the elastic cables holding the seat in the stowed position. If one forgets to attach the cable, the seat is not held in position and risks falling back inopportunely, which is detrimental to safety.
Document U.S. Pat. No. 5,626,391 shows a removable seat that can be tilted by pivoting the seat pan forward. The seat is held in the raised tilted forward position by a hinged lug which is kept under the seat pan when the seat is in the position for normal use and is unfolded to form a strut bearing on the floor to support the seat in the stowed position. This lug is deployed manually by a handle which can be either specifically for this purpose or be common to the control for releasing the rear feet of the seat and tilting the seat pan. Whatever the case, the positioning of this supporting lug requires a user action, and therefore the risk of forgetting it cannot be excluded. Furthermore, the positioning of this lug governs the locking of seat foot anchoring to the vehicle floor by means of a pivoting hook, such that the seat stays held on the floor when in the stowed position.
This locking system serves no purpose in the seat mentioned in the above document when in the normal utilization position, because the front feet are anchored by engaging a groove in the foot, that opens out towards the front of the foot, with an anchoring rod attached to the floor, with the groove extending horizontally when the seat pan itself is in the horizontal sitting position. Consequently, the lower edge of this groove forms a hook that engages beneath the said anchoring rod, with no possibility of disengaging upwards when the seat pan is in the sitting position, and is also blocked horizontally by the connection between the rear foot and the floor. The seat pan pivots around the anchoring rod, which allows the seat to be removed when the seat pan is raised, which brings the groove in the foot to a roughly vertical position thereby allowing the foot to be upwardly disengaged from the anchoring rod. The pivoting hook, which is operated at the same time as the lug for maintaining the seat in the stowed position thus serves to prevent said disengagement when the seat has to remain connected to the floor in this position.
Such a system is complex and requires numerous hinged parts, which can be sources of noise and entail high costs in parts and assembly labour, as well as increasing the weight of the seat. As a specific manoeuvre is required to maintain the seat in the raised position, it does not ensure adequate safety due to the risk of omitting to block it after tilting the seat. In addition, the system in the above mentioned document is designed for seats that tilt by pivoting of the feet with respect to the vehicle floor, and is not well suited to seats whose front feet, as it is the case with the seats targeted by the invention, are rigidly connected to the floor in the locked position, and where the seat pan pivots with respect to the said feet.
The present invention aims to solve the problems mentioned above and propose a simple attaching system that ensures both reliable maintaining of the seat in the stowed position and locking of the seat-to-floor anchoring mechanism, when the seat is in the normal utilization position.
With these aims in view, the subject of the invention is a removable automobile vehicle seat with a tilting seat pan, featuring at least one device for connecting the front of the seat to the floor of vehicle, this device comprising:
an anchoring foot comprising suitable positioning means for positioning the foot on an anchoring part that is attached to the floor, and a pivoting lock on the foot that engages in a locking position with the anchoring foot so as to immobilize the foot on the floor, and
a lug for connecting seat pan frame to the foot, the connecting lug being joined to the seat frame and mounted to pivot on the foot around a transverse axis to allow the seat pan to pivot between a roughly horizontal position of normal use and a tilted forward position.
In accordance with the invention, the seat is characterized in that the said lug comprises:
an arm designed to be able to bear against a stop on the pivoting lock to cause it to pivot towards the locking position when the seat pan is moved towards the normal utilization position, and block the lock in the locking position as long as the seat pan is maintained in the normal utilization position,
a cam-shaped section that works in conjunction with a locking latch mounted on the foot, the latch featuring spring return means that cause automatic engagement of the latch with the cam when the seat pan is pivoted to the tilted forward position, to prevent pivoting of the cam in the opposite direction and maintain the seat in the tilted position.
As already understood by one skill in the art, the cam and latch system enables the seat to be automatically maintained in its stowed position when it is tilted sufficiently far forward for the latch to engage in the cam locking position, which prevents it from pivoting rearwards. The seat cannot be tilted to return the seat pan to the normal utilization position until the latch has been disengaged from the spring return mechanism, in a position allowing pivoting of the cam and hence of the seat pan. During the manoeuvre to place the seat in the stowed position, the pivoting of the seat pan is accompanied by the pivoting of the connecting lug and therefore of the cam, which firstly pushes back the latch against the spring return mechanism, then, when the contact point of the latch has passed the xe2x80x9csummitxe2x80x9d of the cam, lets the latch return beneath the cam to the locking position.
Moreover, when the seat is in the normal utilization position, the arm of the connecting lug prevents the pivoting lock from disengaging, thereby ensuring total protection against any risk of separation of the seat from the floor. The seat cannot be removed until the seat pan has been pivoted sufficiently far forward to disengage the lug from the stop of the pivoting lock, thereby allowing the lock to pivot, enabling the foot to be raised off the floor.
Moreover, when reinstalling the seat in the vehicle, for example, it suffices, with the seat pan tilted forward, to position the foot correctly in the corresponding anchoring part of the floor, and then tilt the seat pan rearwards, which engages the arm with the stop of the pivoting lock and, by making it pivot, brings it automatically into the locking position when the seat pan is finally in the normal utilization position. If the seat is then folded into the stowed position, the foot will remain anchored to the floor until the pivoting lock is intentionally released. There is therefore no risk of the seat becoming inopportunely and unintentionally separated from the floor, whether in the normal utilization position or in the stowed position.
In a preferential arrangement of the invention, the cam-shaped part and the arm are made up by a single part element, situated roughly in a plane perpendicular to the seat pan pivoting axis, and forming an integral part of the connecting lug. Thus, as will be more clearly understood later, it is an integral part of the lug that is shaped to constitute the arm, and whose edge constitutes the cam, with the tip of the arm that bears on the stop of the pivoting lock forming the xe2x80x9ctipxe2x80x9d of the said cam. A single part of the lug thus ensures the two functions of maintaining the seat pan in the tilted position and double-locking of the foot on the floor of the vehicle.
In a complementary arrangement, the lug features two of the said parts, situated symmetrically with respect to a median plan perpendicular to the pivoting axis, and in parallel near each of the sidewalls of the foot.
In other specific arrangements:
the latch is made up by a link rod mounted to pivot on the foot and of which the end distal to its pivoting axis features a finger that bears on the cam;
the finger is held against the cam by a return spring mounted on the link rod pivot spindle;
at least one end of the finger constitutes a rotation travel stop that comes to bear on the sidewalls of the foot to limit pivoting of the link rod with respect to the foot;
the finger extends laterally beyond the cam to form a pickup component for pivoting the link rod against the return effect of the spring;
the foot features towards its front a travel stop that limits forward pivoting of the lug;
the pivoting lock features a manual release handle.
the pivoting lock features two side plates interconnected by a crosspiece that constitutes the said lock travel stop.
Other characteristics and advantages will be mentioned in the subsequent description of a car rear seat in conformity with the invention.

Mechanism for joining a removable seat with tilting seat pan to the floor of an automobile vehicle


A laser marking apparatus and method for marking the surface of a semiconductor chip are described herein. A laser beam is directed to a location on the surface of the chip where a laser reactive material, such as a pigment containing epoxy is present. The heat associated with the laser beam causes the laser reactive material to fuse to the surface of the chip creating a visibly distinct mark in contrast to the rest of the surface of the chip. Only reactive material contacted by the laser fuses to the chip surface, and the remaining residue on the non-irradiated portion can be readily removed.

1. Field of the Invention
This invention relates generally to laser marking techniques and, more specifically, to an apparatus and method for marking the surface of a bare or packaged semiconductor device comprising one or more dice, using a laser and a laser reactive material.
2. State of the Art
Since the first semiconductor devices became commercially available, manufacturers have found it necessary to mark each chip or assembly of chips (bare die or package) with the company name, a part or serial number, or other information such as lot number or die location. Conventional marking methods utilize a mechanical device to transfer ink contained in an ink pad to the surface of a stamp. An individual chip is then stamped, and the automated process is repeated for subsequent chips.
Because of its mechanical nature and the drying time associated with ink, an ink stamping process is relatively slow. Moreover, if the mark is accidentally touched prior to complete drying, the mark will smudge. In chip manufacturing processes using such an ink stamping method, the ink marking operation may have to be included at a relatively early stage of production (if the die itself is to be marked) or just after post-encapsulation processing (if the package is to be marked) to allow for drying time without affecting the production rate. Such early marking may result, however, in marking defective chips that never make it completely through the manufacturing process.
Another problem associated with ink stamping methods is that the quality of ink stamped marks may substantially vary over time. This variation may be dependent upon the quantity of ink applied, ambient temperature and humidity, and/or the condition of the surface of the stamp. In any event, the consistency of a stamped mark may vary widely from chip to chip.
As a result of the deficiencies associated with ink stamping, it has become increasingly popular to use a laser beam to mark the surface of a chip. Unlike ink stamping, laser marking is very fast, requires no curing time, has a consistently high quality, and can take place at the end of the manufacturing process so that only good chips are marked.
Various machines and methods have been developed for marking a chip with a laser. As illustrated in U.S. Pat. No. 5,357,077 to Tsuruta, U.S. Pat. No. 5,329,090 to Woelki et al., U.S. Pat. No. 4,945,204 to Nakamura et al., U.S. Pat. No. 4,638,144 to Latta, Jr., U.S. Pat. No. 4,585,931 to Duncan et al., U.S. Pat. No. 4,375,025 to Carlson, a semiconductor device is placed in a position where a laser beam, usually produced by a carbon dioxide, Nd:YAG, or Nd:YLF laser, inscribes various characters or other information on a surface of the semiconductor device. Basically, the laser beam burns the surface of the chip such that a different reflectivity from the rest of the chip surface is formed. By holding the chip at a proper angle to a light source, the information inscribed on the chip by the laser can be read. Various materials are known in the art that are laser reactive (e.g., capable of changing color when contacted by a laser beam). As described in U.S. Pat. Nos. 4,861,620 to Azuma et al., U.S. Pat. No. 4,753,863 to Spanjer, and U.S. Pat. No. 4,707,722 to Folk et al., the part or component may be partially comprised of the laser markable material or have a coating of the material on the surface of the part or component to be marked.
Using a laser to mark a chip is a fast and economical means of marking. There are, however, certain disadvantages associated with state-of-the-art laser marking techniques that merely burn the surface to achieve the desired mark in comparison to ink stamping. For example, ink stamping provides a clearly visible image on the surface of a chip at nearly every angle of incidence to a light source. A mark burned in a surface by a laser, on the other hand, may only be visible at select angles of incidence to a light source. Further, oils or other contaminants deposited on the chip surface subsequent to marking may blur or even obscure the mark. Additionally, because the laser actually burns the surface of the work piece, for bare die marking, the associated burning may damage the internal circuitry of the chip directly or by increasing internal die temperature beyond acceptable limits. Moreover, where the manufactured part is not produced of a laser reactive material, laser reactive coatings applied to the surface of a component may take hours to cure.
Thus, it would be advantageous to provide a marking technique that combines the speed and precision of laser marking with the contrast and distinctiveness of ink stamping, without any substantial curing or drying time. Moreover, it would be advantageous to develop a method and apparatus for marking the surface of a semiconductor chip that does not harm the circuitry enclosed therein.
According to the present invention, a laser marking apparatus and method are disclosed wherein an object is subjected to a laser beam or other suitable energy source for marking purposes. While the laser beam is actively marking, a substance is introduced into the marking work area that interacts with the laser beam. The substance reacts with the localized heat created by the laser and forms a new compound on the surface of the package or surface of the chip. This new compound is selected to contrast highly with the color and/or surface texture of the surface that has been marked.
In another particular aspect of the invention, the surface of a chip is at least partially covered with a laser reactive substance prior to being contacted by a laser beam. The substance may be in either liquid or powder form and may be rolled on, sprayed on, or otherwise applied by means known in the art. When subjected to the localized heat created by the laser, a semi-permanent, solvent-removable mark is formed and bonded to the surface of the chip. The excess material on the non-irradiated portion, that is, the portion of the surface not contacted by the laser beam, is readily removed by an exhaust or residue removal system and may be recycled for future marking.
In another, more particular aspect of the invention, an ink bearing material, or other pigmented or laser reactive substance-bearing material is disposed adjacent to an exposed surface of a chip. The laser beam transfers ink contained in the ink bearing material to the exposed surface of the chip. For example, the ink bearing material may comprise a ribbon contained in a ribbon dispenser. During the marking process, as the laser beam transfers ink from one point on the ribbon to the chip, another segment of the ribbon may be exposed to the laser beam for subsequent markings. Such an ink bearing material may also help to reduce heat produced by the laser beam from substantially penetrating the surface of the marked chip.
In a more particular aspect of the invention, a stream of atomized particles of B-stage epoxy with an added pigment of a desired color (white for example) is directed at the surface where the laser is actively marking the specimen. The epoxy reacts to the heat of the laser and cures to a visible white image coincident with the path of the laser. The excess particles, those which have not been directly irradiated by the laser beam, may be removed along with other debris from the work area by a debris removal system.
In another, more particular aspect of the invention, much of the epoxy is destroyed by the laser. A thermal gradient, however, along the trailing edge of the laser path causes the epoxy to cure normally into a final and permanent state, thus producing the desired mark.
In another particular aspect of the invention, the laser reactive material absorbs most of the heat produced by the laser. As a result, the delicate internal circuitry of the chip is not exposed to this potentially damaging heat.
In another aspect of the invention, subsequent to or while being marked, the chip is subjected to a jet of coolant to rapidly cool the markings and prevent or reduce the potential for heat damage to the chip. The coolant may be in a liquid, gas, or solid state. In this manner, any residual heat contained in the marking material or present in the surface of the chip may be rapidly dissipated. The markings are thus completely cured and/or cool before exiting the marking apparatus.
In another, more particular aspect of the invention, the laser marking apparatus is computer controlled. In addition to controlling the laser beam, chip location, and other process parameters, the central processing unit (CPU) may control the quality of markings. If so, the marked chips may be subjected to a camera which feeds an image of each chip to the CPU. The CPU compares the pixels of the captured image to a given resolution standard. If the marking is of a sufficiently high quality, the chips are automatically accepted. If not, the chips are automatically rejected for rework and remarking.


A wheelchair restraint system for a mass transportation vehicle having a securement area for a wheelchair is disclosed which includes a barrier carried at a rear portion of the securement area disposed generally transverse to the longitudinal vehicle axis. A rear wheelchair attachment assembly is carried by the rear barrier for anchoring the wheelchair to the barrier. A personal securement belt assembly secures a seated wheelchair occupant to the wheelchair in the securement area. A front bulkhead extends generally transverse to the longitudinal vehicle axis at a front portion of the securement area which includes an extendable anchor member which extends transverse relative to the longitudinal vehicle axis. The anchor member is extendable between a stored position in which the anchor member is stowed within the bulkhead and a deployed position wherein the anchor member is extended from the bulkhead. A front wheel chair attachment assembly includes two attachment belts extending from the wheel chair to a first anchor location on the bulkhead and to a second anchor location on the extendable anchor member when the anchor member is in the deployed position. The first and second front attachment belts diverge outwardly and incline downwardly from the wheelchair toward the respective first and second anchor locations on the bulkhead to effectively anchor the occupant and wheelchair and prevent lateral tipping.

This invention relates to a wheelchair restraint system for securing a wheelchair and occupant in a mass transportation vehicle such as a bus, train, and the like, and more particularly to a three-point wheelchair restraint system in which the wheelchair is effectively restrained which may be easily stored out of the way when not in use.
Heretofore, wheelchair restraint systems have been utilized on transportation vehicles using various forms of bars, belts, anchors, and clips, and clamps. However, the problem arises that implementation of these systems is often laborious and time consuming. Typically the bus driver must fold a flip seat, remove belts from an underneath storage, anchor the belts in floor slots, and attach the belts to the wheelchair. After the wheelchair occupant is transported, the bus driver must then stop and remove the belts, anchors, and store the belts. Often, the belts are left out and form a hazard for tripping over. Typically the anchor slots and floor wells used to anchor the belt also present trip and fall hazards.
Other securement systems for wheelchairs have been proposed in the prior art such as that disclosed in U.S. Pat. No. 4,103,394 wherein a rear barrier is provided to which a lap belt may be fastened for a wheelchair occupant and a pivotal restraint arm is pivotally attached to the underneath portion of a flip seat which may be pivoted to a cantilevered position in front of the wheelchair occupant to restrain the wheelchair. Other various forms of wheelchair securement systems are disclosed in U.S. Pat. Nos. 5,344,265; 4,455,046; and 4,093,303 using various forms of levers, clamps, bars, straps and the like. However, these systems leave much to be desired in providing a simple restraint system for effectively securing a wheelchair and its occupant wherein the securement system may be readily deployed for use and stored to prevent a hazard to the regular passenger when not in use.
Accordingly, an object of the present invention is to provide a wheelchair restraint system for a transportation vehicle which is easy to deploy yet provides a highly effective securement of the wheelchair.
Another object of the present invention is to provide a wheelchair restraint system which may be rapidly deployed and does not require the presence of structures, intrusive abutments and other hazards in the securement area when the system is not deployed.
Another object of the present invention is to provide a wheelchair restraint system which is restrained by a three-point anchoring system to effectively prevent tipping of a wheelchair and its occupant yet provide rapidly deployable system whose elements may be readily stored when not in use for a nonhazardous securement area.
Yet another object of the invention is to provide a simple wheelchair restraint system using a system of retractable belt assemblies to secure the wheelchair in a quick and easy manner.
Still another important object of the present invention is to provide a three-point wheelchair restraint system wherein the anchor point structures may be stored out of sight when not in use to provide a safe and easy to use environment.
The above objectives are accomplished according to the present invention by providing a wheelchair restraint system for a mass transportation vehicle having a securement area for a wheelchair which includes at least one flip seat. The system comprises a barrier carried at a rear portion of the securement area disposed generally transverse to the longitudinal vehicle axis. A rear wheelchair attachment assembly is carried by the rear barrier for anchoring the wheelchair to the barrier. The rear wheelchair attachment assembly has at least two rear attachment elements for attachment at two spaced locations to the wheelchair. A personal securement belt assembly secures a seated wheelchair occupant to the wheelchair in the securement area. A front bulkhead extends generally transverse to the longitudinal vehicle axis at a front portion of the securement area; and a front wheelchair attachment assembly anchors the wheelchair to the bulkhead. The front wheelchair attachment assembly has at least two front attachment elements for attachment to two spaced locations of the wheelchair and the bulkhead. The rear wheelchair attachment assembly includes at least one retractor mechanism for exerting an adjustable force on the wheelchair in a first direction along the vehicle axis, and the front wheel attachment assembly includes at least one retractor mechanism for exerting an adjustable force on the wheelchair in a second direction opposite to the first direction so that the wheelchair is secured between the barrier and bulkhead by the rear and front wheelchair attachment assemblies.
Advantageously, the system includes a coupling having a rear connector, and the first and second attachment elements of the rear wheelchair attachment assembly are affixed to the coupling. The retracting mechanism of the rear wheelchair attachment assembly is connected to the rear connector of the coupling. Preferably, the rear wheelchair retractor mechanism includes a rear retractable belt having a retracted and withdrawn configuration, a release for releasing the belt from the retracted and withdrawn configurations, and a crank for manually tightening the belt when tensioned in the withdrawn configuration. The attachment elements of the rear wheelchair attachment assembly include a first rear attachment belt for attachment to a first rear location of the wheelchair and a second rear belt for attachment to a second rear location of the wheelchair spaced from the first location, and the coupling couples the first and second belts to the rear retractable belt. Preferably, the coupling comprises a plate having a center attachment for attachment to the rear retracting belt, and the first and second rear attachment belts being affixed to the plate at locations spaced equal distances from the center attachment.
Advantageously, the front wheel attachment assembly comprising a first front attachment belt for attachment to a first front location of the wheelchair, a second front attachment belt for attachment to a second front location of the wheelchair spaced from the first front location. A first and a second retractor mechanism is provided for retracting the respective first and second belts in a direction to place a tensioning force on the first and second front belts, and the retractor mechanisms include a manual crank for tightening the tensioned first and second belts. The first and second rear attachment belts diverge outwardly from the respective first and second wheelchair locations toward the anchor locations on the bulkhead to effectively prevent lateral tipping. Preferably, the first and second front attachment belts are also inclined downward from the wheelchair to the front bulkhead. The attachment belts diverge outwardly at an angle in a range of about 0 to 15 degrees with respect to the vehicle longitudinal axis, the preferred value being an angle of about 5 degrees with respect to the vehicle longitudinal axis for a standard wheelchair having a 20xe2x80x3 wheel spacing.
In an advantageous aspect of the invention, the front bulkhead includes an extendable anchor member which extends transverse relative to the longitudinal vehicle axis, the anchor member is extendable between a stored position in which the anchor member is stowed with the bulkhead and a deployed position wherein the anchor member is extended from the bulkhead. A first retractor mechanism is carried by the extendable anchor member, and a second retractor mechanism carried by the bulkhead. Preferably, the bulkhead comprises a bulkhead housing, and the anchor member is placed entirely within the bulkhead housing in the stored position. The bulkhead housing includes an opening, and the extendable anchor member moves through the opening when moving between the stored and extended positions. A movable closure is provided for closing the opening of the bulkhead, and the closure forms a track for guiding movement of the anchor member between the stored and extended positions when the closure is open.
The personal securement strap assembly comprises a lap belt affixed near the rear barrier, and a shoulder belt attachable to the lap belt. An adjustable ring tether supports the shoulder belt wherein the ring tether is adjustable to adjust an upper position of the shoulder belt in a vertical direction to accommodate wheelchair occupants of different heights.

Wheelchair restraint system for a transportation vehicle