A composition comprising, preferably, at least partially defatted meal from a plant source containing protein-bound tryptophan that, preferably, has a higher tryptophan source than said plant source and a physiologically-acceptable diluent or carrier therefor for enhancing sexual desire and performance in a mammal. The composition, preferably, includes a carbohydrate. The invention provides a method of enhancing sexual desire and performance in a mammal having a composition described above.

This invention relates to compositions comprising natural sources of tryptophan, particularly protein-bound tryptophan from plants, processes for making said compositions; physical formulations of said compositions, and use of said compositions for enhancing sexual desire and performance in mammals.
Tryptophan is an essential amino acid found in numerous naturally occurring plant proteins and which has a number of interesting medicinal qualities including treatment of insomnia as well as an adjunct in the treatment of a number of psychiatric disorders. After absorption, tryptophan circulates in the blood as approximately 80% bound to plasma albumin with the remaining 20% circulating as free tryptophan, and under appropriate conditions, tryptophan is transported into the brain. Once across the blood brain barrier (BBB), tryptophan becomes available for metabolism into serotonin, a neurotransmitter implicated in mood and sleep regulation (Boman, 1988). Serotonin, in turn, is metabolized to melatonin; a sleep related hormone found in the pineal gland, a small cone-like structure in the epithalamus of the brain that regulates the 24-hour circadian rhythm in humans. Ingestion of a sufficient quantity of tryptophan per se consistently results in reduced sleep latency i.e. the time from xe2x80x9clights outxe2x80x9d to sleep, and an improvement in overall quality of sleep through improved sleep architecture (Boman, 1988). Tryptophan metabolism to serotonin also serves well in conditions where depleted serotonin levels exists such as anxiety disorders, depression, obsessive-compulsive some pain disorders, aggression and eating disorders.
The hypnotic effects of tryptophan are well studied and follow a fairly flat dose-response curve with a plateau at approximately 1000 mg (for review see Schneider-Helmut and Spinweber, 1986). When given alone, as little as 250 mg of tryptophan is sufficient to produce improved sleep in people with mild insomnia, or in those reporting longer-than-average sleep latency (Hartmann and Spinweber, 1976; Hartmann 1982). Dosages of 1000 mg are associated with more consistent results (Schneider-Helmut and Spinweber, 1986) but higher dosages (2,000-12,000 mg) offer little extra benefit and, indeed, the highest dosages (12,000 mg) are associated with disrupted sleep architecture despite a reduction in sleep latency (Griffiths et al 1972).
The aforesaid medical conditions have been addressed in PCT published application No. WO 01/89319, published Nov. 29, 2001, in the names of Hudson, Susan P. and Hudson, Craig J. Aforesaid WO 01/89319 describes compositions comprising at least partially defatted meal from a plant source containing protein-bound tryptophan, preferably squash seeds, and, optionally, a carbohydrate source provided in an amount capable of facilitating transport of in vivo generated tryptophan across the blood brain barrier. Also described are dietary supplements, foods and beverages comprising the composition of the invention to induce sleep, address an anxiety disorder, depression, obsessive compulsive, aggression chronic pain and eating disorder or provide tryptophan supplementation to individuals in need thereof.
It is generally accepted that medications that increase brain serotonin levels will result in reduced libido as well as reduced overall sexual function (Bradford 2001). Medications associated with reduced libido, include antidepressants, especially those in the Selective Serotonin Reuptake Inhibitor (SSRI) class, as well as the serotonin precursor, tryptophan (Young 1986).
There are previous rare reports of increased sexual desire/function in persons that have taken substantial dosages of tryptophan, i.e. in excess of 6 gm per day.
Further, previous reports suggest that essentially all persons that have reported increased sexual desire or performance while taking tryptophan were also taking concomitant medications. There are no reports of tryptophan resulting in increased sexual desire or performance in instances where tryptophan was taken alone in relatively low doses as an orphan medication.
Yet further, there are no reports of the effect of tryptophan-bound proteins in enhancing sexual desire or performance.
We have surprisingly discovered that aforesaid as defined in WO 01/89319 at least partially defatted meal compositions provide enhances sexual desire and performance in a mammal.
We have surprisingly discovered that human subjects in a selected sleep study who ingested a high protein food composition rich in protein-bound tryptophan reported an increase in sexual desire and performance. These results were from studies that provided very much lower amounts ( less than 250 mg) of possible tryptophan per se as calculated from the tryptophan-bound protein ingested, relative to the amounts described in the aforesaid prior art ( greater than 6 gm/day).
Thus, it is an object of the present invention to provide a plant source of tryptophan for use in enhancing sexual desire and performance in mammals.
Accordingly, in one aspect the invention provides a composition comprising a meal from a plant source containing protein-bound tryptophan, and a physiologically acceptable diluent or carrier therefore for enhancing sexual desire and performance in mammals.
Most preferably, the meal is at least partially defatted.
The naturally derived, tryptophan-rich compositions developed according to aforesaid WO 01/89319 by enriching the protein-bound tryptophan content of a tryptophan-rich protein source have been found to enhance sexual desire and performance in mammals. Compositions of use in the invention comprise a plant source naturally containing protein-bound tryptophan, preferably squash seeds, such as butternut squash seeds, peppercorn squash seeds and pumpkin seeds. Preferably, the plant source is at least partially defatted to concentrate the protein-bound tryptophan content. The composition further, preferably, comprises a carbohydrate source, such as glucose, in an amount sufficient to enhance uptake of tryptophan across the blood brain barrier and to circumvent the competition for BBB transport sites into the central nervous system (CNS). The composition can further optionally comprise physiologically acceptable vehicle(s), flavorings, colors and other nutrients, such as vitamins, preferably vitamin B3 and/or vitamin B6.
In a preferred embodiment, the composition comprises at least partially defatted squash seeds, particularly butternut squash, pumpkin and peppercorn squash seeds, glucose and vitamins B3 and B6.
The invention further pertains to dietary supplements, in the form of, e.g. a tablet, powder, suspension, liquid, capsule or gel; foods, e.g., dietary bar, cookie, baked good, snack food, candy, candy bars, beverages and like edible foods comprising the composition of the invention.
It is described in aforesaid WO 01/89319 that using second derivative spectroscopy, that certain plant sources and, specifically, plant seeds possess relatively high levels of protein-bound tryptophan and that these materials can be used to provide tryptophan in vivo. A process was developed to produce edible compositions having enhanced levels of protein-bound tryptophan as a natural protein source of tryptophan richer than the known natural source. Plants that use gramine typically contain high levels of tryptophan and can be used herein as the plant source. It is desirable, but not essential, that the starting plant material contain at least 200 mg/100 g or at least 0.2% tryptophan in its protein-bound form. Tryptophan concentration can be determined using known methods, including, for example, high pressure liquid chromatography (HPLC), second derivative spectroscopy or any other known methodology. Second derivative spectroscopy is the preferred method to quantitatively analyze tryptophan levels as it eliminates background absorbence.
According to an embodiment of the invention, protein-bound tryptophan levels present in the plant material source are enhanced using a series of steps to extract oil from the plant material to render the material partially defatted. The plant source can be a seed such as, for example, but not limited to, butternut squash seed, peppercorn squash seed, pumpkin seed, lentil seed, sunflower seed, flax seed, watermelon seed, sisymbrium seed, cotton seed, sesame seed, canola seed, evening primrose seed, barley, safflower seed, alfalfa seed, soy beans and combinations thereof. Preferably, the seed is a butternut squash seed as it is believed to contain the highest ratio of tryptophan to total proteins, relative to other seed types. The plant source can also be a vegetative part of the plant, such as alfalfa, seaweed or kelp. Although it is preferred to partially defat the plant source to enhance protein-bound tryptophan levels, defatting is not essential to practice the invention.
Aforesaid WO 01/89319 describes a method for producing an enriched, natural source of tryptophan, comprising identifying a naturally occurring source of protein-bound tryptophan in a plant source; compressing the plant source under conditions sufficient to release oil contained therein; and at least partially removing the oil contained therein to yield a partially defatted plant source that has a higher tryptophan source than the starting material.
In the case of seeds, it is not necessary to remove their seed coat or hull to expose the endosperm prior to processing. The seed, preferably in one embodiment, is first processed through a series of smooth rollers to produce a thin flake in a process known as flaking. This step allows the oil cells to at least partially rupture and increases the surface area of the seeds for further treatment.
The flaked seeds are subsequently heat treated in a process known as cooking or conditioning to further rupture oil cells and increase the oil viscosity for subsequent defatting. The conditioning step can be performed using, for example, a microwave, an oven or by indirect steam. The temperature of the conditioning step should be sufficient to rupture the oil cells and increase the viscosity of the oil without detrimentally destroying proteins contained in the plant material. Preferably, the temperature is from about 40xc2x0 C. to about 50xc2x0 C. The conditioning step is performed for a period of time sufficient to achieve the goal temperature.
Prior to cooling, the heated seed flakes are then mechanically pressed to at least partially remove the oil contained therein. Any known mechanical press or expeller can be used, such as, for example, a Gusta Lab Press. The degree of defatting depends in part on the flaking and cooking steps performed, temperature and oil viscosity and the pressure exerted on the seed. Typically, from about two thirds to about three quarters of the oil is preferably removed.
The pressed plant material can then be further processed depending upon the end user. For example, the plant material can be milled using any conventional means, such as, but not limited to a disk mill, hammer mill or pin mill. The type of mill selected depends in part upon the consistency of the product desired. For example, a pin mill yields a product having a flour-like consistency, while the disk mill or the hammer mill yields a product with a granular consistency.
The hereinabove process yields a natural source of protein-bound tryptophan having a tryptophan content that is greater than in its parent plant source. Preferably, the material should provide at least 0.2% by weight tryptophan. The resultant, at least partially, defatted seed meal can then be incorporated into compositions useful for enhancing sexual desire and performance.
In addition to the partially defatted meal, the compositions of use in the practise of the invention further, preferably, comprise a carbohydrate source with a high glycemic index, preferably in the form of glucose, although sucrose and other sugars that breakdown into glucose can be used. Without being bound by theory, it is believed that the carbohydrate source facilitates the uptake of tryptophan per se across the blood brain barrier, where it is made available for metabolism into serotonin. In the human, a barrier exists that allows the brain functions to operate in an independent environment from the rest of the body in order to protect the sensitive nature of the CNS. This barrier is the result of countless tight junctions between the cerebral endothelial cells at the blood-brain interface that restricts diffusion into the brain (Saunders et al., 1991). Superimposed on the diffusion provided by the tight junctions is a series of transport mechanisms into and out of the brain that regulate the internal environment of the brain with respect to a wide range of molecules including electrolytes, glucose, vitamins and amino acids. The transport mechanism for tryptophan is utilized also by other large neutral amino acids (LNAA) as well (Lajtha, 1974; Betz and Goldstein, 1978). Competition for these transport sites, it is believed, is the reason that a large high protein meal fails to induce a hypnotic effect despite containing sufficient tryptophan (Moller, 1983). Conversely, in the same study, high carbohydrate meals with relatively small amounts of tryptophan did induce a mild hypnotic effect. This apparent contradiction may be explained by the shunting of competing LNAA to liver and muscle tissue at times of relatively high insulin serum levels (Fernstrom and Wurtman, 1971). Tryptophan is not shunted in this manner and consequently, any free tryptophan is afforded an insulin-induced competitive advantage of the transport sites across the BBB.
The carbohydrate source, preferably, is present in an amount sufficient to induce an increase in blood insulin levels in the individual consuming the composition. The tryptophan/LNAA ratio increases with increased insulin levels. An increase from 15 microunits/ml to 60 microunits/ml results in an approximately 35% increase in the tryptophan/LNAA ratio. This level of increase is sufficient although less significant increases will also be beneficial. Preferably, the amount of glucose present in the composition is from about 25 g to about 150 g, with 75 g being most preferred. The amount of tryptophan will remain constant but increases in the carbohydrate will increase the tryptophan/LNAA ratio. Other carbohydrate sources may include maltose, sucrose, and the like, but, preferably, not fructose, in view of its low glycemic index. For individuals that are obese or have type II diabetes, a higher amount of carbohydrate e.g., 100 g, may be required because of abnormal insulin responses to glucose.
Since, approximately 80% of tryptophan is protein bound in the blood in vivo, there is only a small pool of free tryptophan that actually competes with other LNAAs for entry into the brain. Consequently, under ordinary conditions plant protein-bound tryptophan that is ingested, is metabolized and, subsequently, quickly stored in the xe2x80x9calbumin reservoirxe2x80x9d and has little impact on the availability of CNS tryptophan unless given in superphysiological amounts. If, however, tryptophan becomes available at a time when insulin levels increase, free fatty acids compete for the xe2x80x9calbumin reservoirxe2x80x9d and convert existing protein-bound to free tryptophan, as well as preventing the incorporation of the newly ingested tryptophan. Thus, whilst the serum levels of competing LNAAs are reduced, two separate sources of tryptophan, i.e. existing protein-bound and new ingested tryptophan result in increased free tryptophan. In view of this, it is desirable to provide a product that contains at least some residual oil content to preserve a portion of the fatty acids present in the plant material or seed. For squash seeds, about 20% residual oil remaining in the seed meal is optimal. For other seeds, it may be necessary to add. other fatty acids back into the partially defatted product to provide the optimal balance of fatty acids. Hydrogenated oils or other oils, such as canola oil, sunflower oil, safflower oil, palm kernel oil, corn oil or milk solids can be added for this purpose.
In a preferred embodiment, the composition of use in the practise of the invention comprises at least partially defatted squash seeds, particularly butternut squash seeds, pumpkin seeds, peppercorn seeds and combinations thereof, glucose in an amount sufficient to facilitate uptake of the tryptophan provided from the squash seeds across the blood brain barrier in the individual consuming the composition, and vitamins B3 and B6 in amounts present to facilitate tryptophan uptake.
In another embodiment, the composition comprises at least partially defatted butternut squash seed meal, e.g., from about 50 g to about 100 g, in an amount sufficient to provide about 250 mg to about 1000 mg tryptophan, and from about 25 g to about 200 g glucose. More particularly preferred is a composition comprising from about 25 g to about 50 g defatted butternut squash seed meal pressed to reduce the oil content by 75% and from about 75 g to about 100 g glucose. Optionally, the composition comprises vitamin B3 and/or vitamin B6. Vitamin B3 can be present in amounts of from about 5 mg to about 50 mg; and vitamin B6 in amounts of from about 0.5 mg to about 50 mg, with 50 mg of each of vitamins B3 and B6 being preferred.
The composition and dietary supplements of the invention are intended to be orally administered daily. The compositions are formulated for the intended use, preferably, as a single daily administration prior to bedtime. Alternatively, the compositions may be formulated in multiple portions for more or less frequent administration as desired. For reasons of size to facilitate ease of swallowing or improved bioabsorption or utilization before sleep or at any desired time, a given dosage may be divided into two, three, or more tablets or capsules, and the like. A daily dosage may be administered as one tablet, as two tablets taken together. The recommended amounts of each ingredient, as described above, serve as a guideline for formulating the supplements of this invention. The actual amount of each ingredient per unit dosage will depend upon the number of units administered to the individual desiring need thereof. This is a matter of product design and is well within the skill of the dietary supplement formulator.
The compositions of use in the present invention may be formulated using any pharmaceutically acceptable forms of the vitamins, minerals and other nutrients discussed above, including their salts. They may be formulated into capsules, tablets, powders, suspensions, gels or liquids optionally comprising a physiologically acceptable carrier, such as but not limited to water, milk, juice, starch, vegetable oils, salt solutions, hydroxymethyl cellulose, carbohydrate. The compositions may be formulated as powders, for example, for mixing with consumable liquids, such as milk, juice, water or consumable gels or syrups for mixing into dietary liquids or foods. The compositions of use this invention may be formulated with other foods or liquids to provide premeasured supplemental foods, such as single servings bars, for example.
The compositions can be made in a variety of forms, such as baked goods, e.g., cookies, brownies, fudge, cake, breads, biscuits, crackers, puddings, confections, i.e., candy, snack foods e.g., pretzels, chips, dietary beverages, ice cream, frozen confections and novelties, or non-baked, extruded food products such as bars. The preferred form is a non-baked extruded nutritional bar.
The compositions can also contain other ingredients such as one or a combination of other vitamins, minerals, antioxidants, fiber and dietary supplements. Selection of one or several of these ingredients is a matter of formulation design, consumer and end-user preference. The amount of these ingredients added to the compositions of use this invention are readily known to the skilled artisan and guidance to such amounts can be provided by the U.S. RDA doses for adults. Vitamins and minerals that can be added include, but are not limited to, calcium phosphate or acetate, tribasic; potassium phosphate, dibasic; magnesium sulfate or oxide; salt (sodium chloride); potassium chloride or acetate; ascorbic acid; ferric orthophosphate; niacin amide; zinc sulfate or oxide; calcium pantothenate; copper gluconate; riboflavin; beta-carotene; pyridoxine hydrochloride; thiamin mononitrate; folic acid; biotin; chromium chloride or picolonate; potassium iodide; sodium selenate; sodium molybdate; phylloquinone; Vitamin D3; cyanocobalamin; sodium selenite; copper sulfate; Vitamin A; Vitamin E; vitamin B6 and hydrochloride thereof; Vitamin C; inositol; Vitamin B12; potassium iodide.
Flavors, coloring agents, spices, nuts and the like can be incorporated into the product. Flavorings can be in the form of flavored extracts, volatile oils, chocolate flavorings, peanut butter flavoring, cookie crumbs, crisp rice, vanilla or any commercially available flavoring. Examples of useful flavorings include but are not limited to pure anise extract, imitation banana extract, imitation cherry extract, chocolate extract, pure lemon extract, pure orange extract, pure peppermint extract, imitation pineapple extract, imitation rum extract, imitation strawberry extract, or pure vanilla extract; or volatile oils, such as balm oil, bay oil, bergamot oil, cedarwood oil, cherry oil, walnut oil, cinnamon oil, clove oil, or peppermint oil; peanut butter, chocolate flavoring, vanilla cookie crumb, butterscotch or toffee. In a preferred embodiment, the dietary supplement contains non-caffeinated cocoa or chocolate, or chocolate substitutes, such as carob. The food compositions may further be coated, for example with a yogurt coating.
Emulsifiers may be added for stability of the final product. Examples of suitable emulsifiers include, but are not limited to, lecithin (e.g., from egg or soy), and/or mono- and di-glycerides. Other emulsifiers are readily apparent to the skilled artisan and selection of suitable emulsifier(s) will depend, in part, upon the formulation and final product.
Preservatives may also be added to the compositions to extend product shelf life. Preferably, preservatives such as potassium sorbate, sodium sorbate, potassium benzoate, sodium benzoate or calcium disodium EDTA are used.
In addition to the carbohydrates described above, the compositions can contain artificial sweeteners, e.g., saccharides, cyclamates, aspartamine, aspartame, acesulfame K, and/or sorbitol. Such artificial sweeteners can be desirable if the dietary supplement is intended for an overweight or obese individual, or an individual with type II diabetes who is prone to hyperglycemia.
To manufacture such a food bar, the liquid ingredients are cooked; the dry ingredients are added with the liquid ingredients in a mixer and mixed until the dough phase is reached; the dough is put into an extruder and extruded; the extruded dough is cut into appropriate lengths; and the product is cooled. For manufacture of other foods or beverages, the ingredients comprising the compositions of use in the practise of this invention can be added to traditional formulations or they can be used to replace traditional ingredients. Those skilled in food formulating will be able to design appropriate foods/beverages with the objective of this invention in mind.
It is noted that there are potential side effects with tryptophan supplementation. Tryptophan at lower dosages have few side effects but there are reports of difficulties at higher dosages or in combination with certain antidepressants. When combined with a monoamine oxidase inhibitor (MAOI), tryptophan carries a risk of delirium and neurological dysfunction (Thomas and Rubin, 1984). At higher dosages (greater than 12 gm per day) the most frequent complaints are daytime sedation and nausea (Hartmann, 1977). There are a few theoretical risks that have been demonstrated in animal models but not in humans. Large dosages of 1-tryptophan produce lipogenesis in animals (Fears and Murrell, 1980) but this effect was not seen in humans (Sourkes, 1983). Similarly there is a theoretical risk that a tryptophan metabolite, xanthurenic acid may lead to the development of diabetes (Kotake and Murakami, 1971). Thus, it is an objective of the present invention to limit the daily amount of protein-bound tryptophan administered to an individual to levels below about 12 gm tryptophan a.i. per day to avoid these potential side effects. In yet a further aspect, the invention provides a process for the manufacture of a pharmaceutical composition when used for enhancing sexual desire and performance in a human said process comprising admixing a composition as hereinbefore defined with a physiologically acceptable carrier therefore.
In a further aspect, the invention provides a method of enhancing sexual desire and performance in a mammal by administering to said mammal an effective amount of a composition as hereinabove defined.

Sexual desire and performance enhancement with protein-bound tryptophan

Scitentia Inc. 275 MacPherson Ave., Suite 105


An optical pulse propogating in an optical guide of an electro-optic medium interacts with a coplanar RF traveling wave to shift the optical wavelength. The RF phase is resynchronized to the optical pulse phase with spatial periodicity to provide a desired phase relationship between RF and optical radiation. A unidirectional incremental wavelength shifter comprises a frequency multiplexer for soliton communication and a symmetrical sideband modulator of this type varies the spectral width of probe illumination in an atomic absorption spectrometer probe beam.

It is known in the prior art to propagate an optical signal through an electro-optic crystal where a radio frequency, RF field is imposed on the crystal. The RF phase is adjusted to modulate the refractive index of the electrooptic medium to adjust the phase approximately linearly with time for the propagating optical pulse. The decreasing optical path produces an effect similar to that of uniform motion of the optical source toward the observer, e.g., a doppler upshift. A 180.degree. shift in the RF phase creates the effect of uniform motion away from the observer (doppler downshift). See Duguay and Hansen, IEEE Journal of Quantum Electronics, QE-4, p. 477, (1968). The effect is reviewed by Kaminow and Turner, Proc. IEEE, vol. 54, pp. 1122-1124 (1966).
In the present work, we describe a different structure wherein an RF traveling wave in an RF guide structure co-propagates with an optical pulse in an optical guide incorporating an electro-optic medium. The RF phase is adjusted in relation to the co-propagating pulse to produce a desired refractive gradient in the electro-optic medium whereby the optical pulse experiences a uni-directional wavelength shift of desired magnitude. In contrast to the lumped element arrangement of prior art (for which the refractive index is constant in space) the present invention yields a refractive index which is a function of space and time.
A very useful arrangement integrates, on a single substrate, the electro-optical modulator with the RF transmission line for use as a component in particular applications.
Consider a light pulse propagating through a nonlinear medium which exhibits a linear electro-optic coupling. A microwave signal E.sub.m propagates coincidentally with the optical pulse. The microwave field EQU E.sub.m =E.sub.0 sin (kz-.omega.t) Equ. 1
produces a dynamic effect upon the refractive index of the nonlinear medium given by EQU n=n.sub.o +.delta.n EQU .delta.n=-(n.sub.0.sup.3 r.sub.c E.sub.m)/2 Equ. 2
where n.sub.0 is the unshifted refractive index of the medium and r.sub.c is the effective first order electro-optic coefficient. Assume that the light pulse is spatially coincident with the microwave phase as illustrated in FIG. 1. As shown, the pulse is so located in time and space that it coincides with an increasing slope of the field E.sub.m and thus a reduced index of refraction at its trailing edge and an increased index of refraction at its leading edge, both instantaneously and locally. This results in the leading edge of the pulse traveling at a reduced velocity with respect to the trailing edge. As a result, the pulse is spatially squeezed. Although the pulse is spatially squeezed, the total number of wave periods or cycles remains the same, yielding a frequency upshift. A frequency downshift may be obtained by synchronizing the optical pulse with the opposite RF phase, e.g., by locating the optical pulse in a region of decreasing electric field E.sub.m. The leading edge of the pulse then propagates at a relatively greater velocity than the trailing edge because the leading edge experiences a lesser index of refraction. Thus the pulse is spatially stretched, the same number of optical cycles occupying a greater spatial length.
In this discussion, it is sufficient to assume a positive electro-optical coefficient although that nothing herein is intended to limit the nature of the medium or the operating range wherein the coefficient has a specific sense.
In general, the refractive index is a function of the wavelength, especially when comparing optical and microwave radiation. As a consequence the optical propagation velocity (more specifically, the group velocity) is usually different from the phase velocity of the RF wavefront. In one embodiment of the present invention, this difference may be ameliorated by introducing period polarity reversals in the transmission line.
The present work embraces both a uni-directional incremental wavelength shift and bidirectional shifting similar to symmetrical sideband modulation. The uni-directional embodiment of the wavelength shifter of the present invention is useful in a wide range of measurement applications. The symmetrical bidirectional embodiment is also well suited for instrumentation as described herein.
In the prior art there has been an application for controlled wavelength shifting in the optical region in the area of atomic absorption spectrometry. It is known in that work to employ the Zeeman (or Stark) effect to shift the emission wavelength of a probe beam obtained from a hollow cathode lamp or the absorption wavelength of a test sample under the influence of an external field as described by U.S. Pat. No. 4,341,470. An electro-optic wavelength shifter has been described for a similar application by Cammann (U.S. Pat. No. 4,834,535). In the latter work an optical modulator is subject to an applied RF field and the optical beam is caused to repeatedly traverse the modulator. The RF field of the reference necessarily has a wavelength which is large compared to the dimensions of the modulator in contrast to the requirements of the present invention wherein an RF traveling wave locally modifies the optical properties of the modulator to provide a spatial and temporal modulation of the optical properties of the electro-optical medium.
It is known to employ the propogation of optical solitons on an optic fiber to support a communication system exhibiting unusually high bit rates. Such a system was studied and described by Mollenauer, Gordan and Islam, IEEE J. of Quant. Elect., vol. QE-22, pp. 157-173 (1986). A practical system of this type requires multiplexing of different channels on the same physical fiber. A frequency multiplexing and demultiplexing apparatus utilizing the present invention is described below.

Spectral modification through phase modulation with spatial extent


A detonation gun for thermal spraying formed by a combustion chamber (1) and a barrel (2), with entrances for fuel (5) and for oxidizer (4), one or more spark plugs (6) for detonating the fuel-oxidizer mixture and one or more injectors (7) for the introduction of the product into the barrel, the gun in the invention centers its characteristics on the incorporation of a direct injection system of the fuel and oxidizer gases into the explosion chamber, producing explosive mixtures of different compositions according to the various zones in the explosion chamber, with a constrained volume existing in this explosion chamber in which only fuel is injected in such a way that it can generate high-energy explosions, maintaining the cyclic operation of the gun. The gun also incorporates in the barrel (2-2xe2x80x2), one or more annular injectors (7), which allow the feeding of various products, and especially coating powder, so that it is possible to increase the number of kilograms deposited on the substrate per unit of time and, in consequence, the gun""s productivity.

This invention refers to a spray gun, of the type used in the industrial thermal spray area for obtaining coatings, especially in detonation spray technologies.
The object of the invention is to achieve a new detonation gun with greater productivity than existing ones, maintaining stable and continued optimum spray conditions in each firing cycle. In relation to previous detonation devices, this gun allows the firing frequency to be increased, together with the amount of powder and feeder gases and in consequence, the amount of coating powder deposited per unit of time, maintaining optimum levels of quality that are characteristic of coating produced by detonation technologies.
For this purpose, a new gas feeding system is proposed, in a new explosion chamber, that permits the gun""s operating frequency to be increased, making it possible to maintain the optimized characteristics of each explosion stable and constant, even at high frequencies and a new system for feeding products in the barrel that allows the distributed injection of products to any point within the barrel achieving an increase of the amount of powder injected into the barrel and reducing the limitations associated with obstruction of feeder ducts, together with great operating versatility by being able to select the injection point.
The barrel feeding system, in addition to the coating powder, it is also useful to introduce other products that can condition the thermal spray process, in this way permitting great flexibility when modifying the operating parameters, by being able to modify the characteristics of the generated explosions and to improve and optimize the coatings obtained in this way.
It is also an object of the invention to achieve better performance from the gun, based on thermally isolating the gases produced in the explosive process with respect to the cooled barrel wall, in order to obtain better use of the energy that is carried by these gases, with the resulting increase in the gun""s performance and its efficiency.
Current detonation spray technologies are mainly used for the application of coatings to parts that are subject to severe conditions of wear, heat or corrosion, and which are fundamentally based on the use of the thermal and kinetic energy produced by the explosion of a gaseous mixture to deposit a coating material powder on these parts.
The coating materials that are usually employed in detonation spray processes include metallic powder, metal-ceramics and ceramics etc, and are applied to improve the resistance to wear, erosion, corrosion and as thermal insulators or as electrical insulators or conductors, among other applications as given in the literature.
Detonation spray is performed with spray guns that basically consist of a tubular explosion chamber with one end closed and the other open, to which a barrel, also tubular, is connected. The explosive gases are injected inside the explosion chamber and ignition of the gas mixture is produced by means of a spark plug, which provokes an explosion and in consequence, a shock or pressure wave that reaches supersonic speeds during its propagation inside the barrel until it leaves the open end.
The coating material powders are usually injected inside the barrel in contact with the explosive mixture so that they are dragged along by the propagating shock wave and by the set of gaseous products from the explosion, which are expulsed at the end of the barrel, and deposited on a substrate or part that has been placed in front of the barrel. This impact of the coating powders on the substrate produces a high density coating with elevated levels of internal cohesion and adherence to the substrate. This process is repeated in a cyclic manner until the part is suitably coated.
In traditional detonation spray equipment, the gases used in the generation of the explosive process are mixed in a separate chamber prior to the explosion chamber, which is then fed by a homogeneous mixture of gases in each explosive cycle. Traditionally, this pre-mixing chamber is isolated from the explosion chamber during the explosive phase for safety reasons, through the use of valves in one or more gas lines, with and without the introduction of an inert gas between two consecutive explosions.
In other, more advanced types of detonation equipment, presented by the applicant in PCT US96/20160, this isolation between the pre-mix and explosion chambers is achieved by using dynamic valves, which means they do not have any moving parts, which overcomes the inherent disadvantages of the previously-mentioned mechanical systems. However, these devices continue to employ a pre-mixing chamber in order to homogenize the gas composition that feeds the explosion chamber.
Recently, the same applicant developed a type of detonation spray equipment, described in PCT ES97/000223, with a gas injection system that does not employ mechanical valves or systems to shut off the gas supply, and, in addition, allows the gases feeding to be fed directly and separately to the explosion chamber through a series of independent passageways, where each passageway is made up of an expansion chamber and a large number of distributor ducts with reduced cross section and/or long length. This results in a system without any moving mechanical parts and/or pre-mixing chamber. In this device, the expansion chamber for each passageway is in direct communication with the corresponding supply line, while the distributor ducts are suitably arranged so that multiple gas injection points open out on the internal surface of the explosion chamber, producing a continuous and separate feeding at multiple points, which guarantees that the combustible mixture is produced directly and in a homogeneous manner, throughout the entire explosion chamber prior to each ignition and with sufficient flow to fill the chamber in each detonation cycle.
In turn, in the application PCT ES98/00015, also of the same applicant, a powder injection system is described for a detonation spray gun consisting of a dosing chamber directly fed by a conventional type continuous powder feeder that communicates with the barrel by means of a direct duct. In this way, the pressure generated by the explosion and which advances along the barrel, passes through the communication duct and undergoes a brusque expansion on reaching the dosing chamber, which interrupts the powder feeding from the continuous feeder and produces complete fluidization of the powder in the dosing chamber. The fluidized powder is carried by the suction towards the barrel, where the pressure wave generated in a new explosive cycle drags it out and deposits it on the surface to be coated.
The detonation guns of the described type produce coatings of excellent quality, but they have a limitation in so far as the amount of powder that can be deposited per unit of time. This is due to the fact that, for a detonation gun of a determined size, the optimum amount of powder that can be processed during each explosion is limited by the existence of a maximum volume of optimized gaseous mixture that may be processed in each explosion and capable of generating proper characteristics of the actual explosive process itself. An increase in the gaseous volumes involved in each explosion on this maximum volume of optimized mixture is not directly translated into an improvement of the explosive process of each cycle, so that an increase in the amount of powder deposited per unit of time should not be obtained so much because of an increase in the powder processed in each explosion, but as a consequence of the increasing in the firing frequency, guaranteeing optimum explosive characteristics of each cycle in all cases.
On the other hand, the repetition of the explosive cycle at high frequencies and generating explosions with characteristics equivalent to those obtained at lower frequencies also requires higher gas flows in order to guarantee constant gas volumes involved in each explosion. The application of these increments in the gas flows and in the firing frequencies in the previously described equipment produces an increase in the gun""s power rating and an increase in the gas supply pressure with an acceleration in the injection and gas mixture processes inside the explosion chamber which causes great difficulty in the maintenance of the actual cyclic detonation process itself, leading to continuous combustion processes and making the spray process impossible with that equipment. In particular, an increase in the gun""s power rating and consequently in the gas injection system temperature makes more difficult the cooling of the gases produced in an explosive cycle and which, returning through the injection system ducts allows the cyclic interruption of the supply of oxidizer and fuel to the chamber.
In the equipment described in PCT ES97/00223, the gases, on their return to the explosion chamber, act as an insulating barrier between the gases produced in the prior explosive cycle and the new gas mixture formed in the explosion chamber, preventing self-ignition. However, the operation of this mechanism at high frequencies is made difficult by an increase in the temperature of the explosion chamber, a reduction in the volume of the return gases that acts as an insulating barrier and their rapid return to the explosion chamber, as a result of the greater pressure in the feed lines. In the previously described detonation devices, this leads to the self-ignition of the combustible mixture and the formation of a continuous combustion process.
In currently existing detonation guns as described in this section, there is an additional limitation that derives from the types of powder feeders used since they cannot guarantee the correct fluidity of the powder at high supply speeds. In this sense, it can be seen that current designs are subject to major problems of obstruction and wall deposits on the feeding ducts above a certain amount of injected powder, and this makes continuous and stable operation very difficult. This is mainly due to the geometric aspects of the powder injection devices and/or thermal aspects in relation to the explosive process. In the injection device described in PCT ES98/00015 from the same applicant, the powder is introduced into the barrel through a single orifice, then carried along by the hot gases generated in the explosive cycle. Any increases in the amount of powder, gases and in the operation frequency in order to increase the productivity of the spray process, will soon come up against a limit in the feeding devices, such as that previously stated, since as a consequence of the accumulation of material in a localized area and in the increase of temperature of the gases that interact with the powder in the injector, obstruction and deposit problems as stated before are produced.
On the other hand, there are spray technologies, known as HVOF, that do not produce cyclic explosions, but a continuous combustion that it used in the formation of a supersonic flow of hot gases that are actually employed in the thermal spray process, requiring, in this case, very high gas flow rates for maintaining this required supersonic flow rate for obtaining coatings with a good technical quality.
Due to the continuous nature of the HVOF processes, the more advanced designs of HVOF guns have a powder processing capacity per unit of time that exceeds that achieved with traditional detonation spray systems, although they still have similar problems in the injection of powder, obstruction and deposits inside the spray nozzles.
However, the lower thermodynamic efficiency of the continuous combustion processes against the explosive processes (pulsed or cyclic combustion) leads to the fact that the amounts of gases and power required to deposit the same amount of powder is greater in the HVOF systems, which results in lower performance in resource use and in the introduction of additional operational problems as a consequence of the high working powers employed in the HVOF systems with high processing capability.
It would be therefore, desirable to have a spray gun that employs a pulsed explosive process, with high thermodynamic efficiency in the use of gases and precursor materials, allowing a significant increase in the amount of powder processed per unit of time, and maintaining the typical characteristics of the coating produced by the detonation technologies.
The detonation spray gun of the invention, allows the working at higher frequencies than those employed in currently existing devices with a large volume of powder feeding, achieving greater deposit rates, even when compared with those obtained with current HVOF continuous combustion equipment, but maintaining the higher thermodynamic efficiency of the explosive processes in the use of the gases and precursors, resulting in greater productivity.
The current detonation spray system is based on the generation of explosive gaseous mixtures of different compositions in different zones of the chamber zone, which is due to a specific design of the gas injectors and the explosion chamber, employing dynamic valves and direct, separate injection for fuel and oxidizer, without pre-mixing of both prior to the explosion chamber itself.
First, in order to enable the gun to operate at high frequencies with high gas volumes per explosion, it has been planned for the gas feeding to the explosion chamber to be produced via several points, spatially distributed throughout the explosion chamber, so that gaseous mixtures are generated with locally varying compositions in the various zones inside this chamber, allowing higher energy explosions to be generated at higher frequencies and maintaining stable cyclic operation.
Inside the explosion chamber, just before the orifices employed for oxidizer feeding, there is a protuberance or internal perimeter rib that determines a narrowing of the internal diameter of the explosion chamber, defining an annular volume which is fed exclusively with fuel through multiple distributors arranged in the rearmost zone of the explosion chamber. This constrained volume favors thermal interchange of the gases produced in the explosion with the cooled chamber wall and also allows an increase in the gas volume that acts as an insulating barrier between the gases involved in two consecutive explosive cycles, and in this way simplifies the maintenance of the pulsed process under the circumstance imposed by the high gas flow rates and high frequency that are the object of this patent.
In accordance with this operating scheme, after each ignition of the spark plug, the propagation of a shock and temperature wave generated by the explosive process, returns to the said constrained annular volume producing the combustion and decomposition of the fuel present in this volume, together with an overpressure that produces an interruption of the fuel feeding supply and even the penetration of the products of combustion via the distribution ducts. The high gas flow rates required in order to work at high frequencies cause this latter factor to be reduced so that new fuel is able to rapidly penetrate the explosion chamber via the distribution ducts, however, this effect is compensated by the presence of this constrained annular volume in the explosion chamber, the content of which in combustion products generates a sufficient amount of gas to act as an insulating barrier between the hot gases originated in the previous explosion and the new gases supplied to the explosion chamber.
The feeding of oxidizer begins in the zones closed to the ignition point (spark plug) to generate a local mixture poor in oxygen, with an injection in this zone of a maximum of 25% of the total volume supplied in each cycle, together with the local injection of the totality of fuel supplied to the explosion chamber.
The rest of the oxidizer is introduced into the explosion chamber in more advanced positions, closer to the tubular barrel, so that the combustion front that is produced at each spark plug ignition meets up with mixtures that are richer in oxidizer as it progresses along the explosion chamber, increasing its speed and energy, producing very energetic explosions that are suitable for the production of high quality coatings.
In this way, it is possible to produce, within the same chamber volume, and for the same explosive cycle, zones of greater and lesser energy. In particular, the new design of explosion chamber and the gas injection system favors the supply of energy to the zone closer to the oxidizer injection, and at the same time reduces the energy of the explosion in the rearmost zone of the explosion chamber, thus increasing the efficiency of the injection system in cooling the gases that accompany the retreating pressure wave and favoring the continuity of the cyclic detonation process at higher frequencies than with the previous devices.
According to a preferable construction, the oxidizer injector is concentrically and internally arranged in the explosion chamber, and has a prolongation at one end that extends practically to the gun""s barrel, this prolongation incorporating a series of orifices obliquely arranged with respect to the gun""s barrel, for the injection of oxidizer in this advanced location in the explosion chamber.
A second characteristic of the gun object of this invention, refers to the incorporation of a system for feeding products at any point of the barrel, a system that when it is used for the injection of coating powder permits an increasing of the amount of powder feed to the gun per unit of time, and therefore the amount of powder deposited on the substrate per unit of time, increasing also the gun""s productivity.
For this reason, the barrel comprises an annular chamber at an intermediate point of the barrel, assisted by one or more material feeding inlets, so that the product introduced through them reaches the inside of the barrel with an annular distribution achieving a good mixture with the gases that are present in the barrel and avoiding the formation of high concentrations of material in specific zones, just as occurs with traditional injectors consisting of radial orifices.
The employment of this type of feeding ducts for the injection of the coating powder permits good distribution of the powder because, instead on entering the barrel through a single point, it does so through the annular chamber and consequently in a more homogeneously distributed manner, reducing the volumetric density of powder injected per unit of area, reducing the problems of blockages, but, in addition, allowing a larger amount of powder to be introduced into the gun.
In accordance with another characteristic of the invention, it has been planned for the mentioned annular chamber to take the form of a flange that divides the chamber in two segments, to allow the flange to be dismounted for injection duct maintenance and the front part of the barrel corresponding to the exit mouth in order to replace it with one having different characteristics, so that the same gun may have several configurations, including various lengths that allows coatings with different materials that require greater or less thermal and/or kinetic energy and hence a longer or shorter barrel.
In a similar fashion, it is also possible to connect segments of barrel having different diameters according to the type of coating powder used or the special characteristics of the current process or application.
It has also been planned for the flange that incorporates the annular injector to be coupled to the gun by means of a device that allows the separation between the flange and the barrel to be varied to established and entrance of external air between the two parts, and even to make one part independent from the other, so that on certain occasions the performance and results of the gun can be improved.
In accordance with another of the invention""s characteristics, it has also been planned that the flange comprises a second annular chamber, with its corresponding inlets for feeding material and which opens to the inside of the barrel and chamber to allow the injection of a product of the same or different characteristics of the one introduced via the main chamber. Specifically, it is possible to introduce powders of different types or to distribute the powder feeding along the length of the barrel, which will permit to obtain a greater versatility in the composition of the coatings obtained.
It is also possible to use the mentioned annular feeding system for the injection of active gases, in such a way that it would be possible to locally modify the nature of the mixture conditioning the explosive process, so, for example, these active gases may modify the energetic characteristics of the actual spraying process itself, modifying the temperatures and speeds applied to the sprayed particles or they can also provide a thermochemical environment that conditions the reactive interaction between these gases and the particles to be deposited, or even produce the synthesis of the materials deposited during the spray process.
Of course, the described annular injector may be single, double or multiple, comprising one or several product feeding inlets and one or more injectors of this type can be distributed along the barrel.
Therefore, by means of the proposed feeding system, it is possible to voluntarily modify the gun""s working conditions, since it is possible to inject all types of products that may modify, both the spray process conditions and the coating composition, and this injection may be made at any point of the barrel and so, as already mentioned, the dimensions of the barrel may be rapidly and simply changed, achieving an enormous flexibility in the gun""s operation and consequently in its capability of processing a wide range of material.
It is also possible to use the described annular injector for the introduction of an inert gas to reduce the transfer of heat between the gases produced in the explosion and the cooled wall of the barrel, thus making use of these gases to best advantage.
In accordance with this structure, the gases produced in the explosion progress along the central zone of the barrel in its output sector, while the gases injected by means of the cited annular chamber flow in contact with the barrel wall, forming a kind of moving cylindrical film that reduces the heat losses of the gases produced in the explosion through contact with the cooled tube that forms the barrel and which determines greater performance from the gun.
In addition, the film of surrounding gases form at the mouth of the barrel what could be called a virtual barrel, that axially lengthens the size of the actual barrel itself, reducing and delaying the mixture of the explosive process products with the gases in the environment, which leads to the fact that with a shorter, lighter barrel, the powder particles are better melted and this produces a coating with better properties.
When using easily oxidized powders, it is possible to carry out the injection with an inert gas, so that the powder is protected from the environmental air by being surrounded by this gas and consequently, the quality of the produced layer or coating is improved.

High frequency pulse rate and high productivity detonation spray gun


A method for image-based driver identification in a motor vehicle is provided. At least one two-dimensional driver facial image is recorded using a camera. Recorded driver facial images are temporarily stored. The temporarily stored driver facial images are compared to two-dimensional reference images of each possible driver from multiple possible drivers of the motor vehicle. The current recording angle between the camera and the facial normal line of the driver is determined by a device not otherwise used for image-based driver identification and relayed to the method for image-based driver identification and the recording of a driver facial image is triggered when the current recording angle reaches a specific preset value.

The present invention relates to a method for image-based driver identification in a motor vehicle by recording at least one two-dimensional driver facial image using a camera, temporarily storing recorded driver facial images, and comparing temporarily stored driver facial images to two-dimensional reference images of each possible driver of multiple possible drivers of the motor vehicle.
The identification of individuals on the basis of visual facial recognition is increasingly used in systems having access/usage restriction. Examples are access to security-critical areas in buildings and the use of motor vehicles. In addition, concepts are known in the motor vehicle field in particular, according to which comfort settings for a specific driver are assumed automatically after the driver has been identified using facial recognition.
For image-based facial recognition of a target person, in particular the driver of a motor vehicle, at least one image of the face is recorded by a camera. The facial image of the target person is subsequently compared by computer to stored reference images of various possible target persons, which are typically saved in a databank. This comparison may be performed on the basis of the pure image data or on the basis of features extracted from the images. The identity of the target person is subsequently judged on the basis of the degree of correspondence established upon the comparison of the images and/or their features.
In principle, it is advantageous for good recognition performance if the images compared to one another have approximately the same recording angle, i.e., the same angle between the recording camera and the facial normal lines of the target person. In addition, the majority of known facial recognition systems are based on the assumption that the essential characteristics of a face may be visually acquired best in frontal recordings.
Therefore, in most known systems, only frontal recordings are saved as reference images in a databank. As facial images of the target persons are recorded, it is also ensured by an appropriate placement of the camera and/or by an appropriate instruction to the target person that an essentially frontally recorded facial image may be generated. The placement of a camera for this purpose is connected to a high technical outlay, however. The necessity of following an instruction in regard to the head positioning and/or orientation by the target person restricts the comfort of the target person. In particular for the driver of a motor vehicle, such a method is not practical in the long-term.
Various newer methods are concerned with the object of making facial recognition more robust in relation to recording angles deviating from one another in the recorded facial image and reference image. The facial recognition can be implemented independently of the availability of a frontal facial image. Feature-based methods are generally distinguished in this case by greater robustness than methods based purely on the analysis of image data (e.g., template matching). However, the best recognition performance is also to be expected in feature-based methods upon the comparison of images having corresponding recording angles, in particular upon the comparison of frontal recordings.
A method is known from U.S. Pat. No. 6,681,032 B2, in which facial images, which are recorded from a non-frontal recording angle, are converted into a frontal image by a computing operation based on a geometrical model. The high computing outlay for the transformation, which may be implemented in an acceptable time only at high cost or not at all in a motor vehicle, is a significant disadvantage of this method. In addition, the quality of a model-based transformation of a non-frontally recorded facial image is undeniably inferior to the quality of a frontally recorded image, even in the event of high model quality.
In general, it is to be noted that methods which claimrobustness in regard to recording angles deviating from one another in the recorded facial image and reference image, such robustness is necessarily accompanied by a reduction of the reliability of a system in regard to incorrect identification. In applications in which permanent and/or repeated access of unauthorized target persons to a facial recognition system is possible under certain circumstances, such as a motor vehicle, such a reduction of the reliability is not acceptable.
Methods which calculate a three-dimensional model of the face of the target person from multiple recorded images are precluded in motor vehicles because of the high computing outlay connected with such a method. In the following, the processing of two-dimensional facial images of a target person and two-dimensional reference images is assumed.
A further approach for solving the problem of an undefined recording angle of the recorded facial image of the target person is to record multiple facial images of a target person from different recording angles and/or to save multiple reference images from different recording angles in a databank for every possible target person. The subsequent comparison of all possible combinations of a facial image to a reference image increases the probability of finding a combination having approximately corresponding recording angles.
A targeted selection of combinations having corresponding recording angles is typically not possible in such methods, because the recording angle itself is not known at least for recorded facial images. Therefore, the computing outlay required increases strongly due to the increasing combinatorial variety with increasing number of recorded facial images and/or saved reference images. Such methods are therefore unsuitable for use in a motor vehicle.
The computing outlay for the comparison operations may be reduced if a device that detects the recording angle are available in a method. Determining the recording angle from the recorded two-dimensional facial images is itself greatly subject to error, however, and requires its own computing outlay. Providing a dedicated device for detecting the recording angle required in the method for facial recognition is connected to significant technical outlay. Both solution approaches are therefore only suitable in a limited way for use in a motor vehicle.
Exemplary embodiments of the present invention provide a low-interaction and reliable method for establishing the identity of the driver of a motor vehicle by facial recognition, which may be performed without providing additional devices and with low computing outlay.
In accordance with exemplary embodiments of the present invention, the current recording angle of a device already existing in the motor vehicle, which is not used for image-based driver identification, is provided. The recording angle may therefore be stipulated as known without providing additional devices.
Furthermore, in accordance with exemplary embodiments of the present invention the recording of a driver facial image is triggered precisely when the current recording angle reaches a determined preset value. It is thus ensured that a driver facial image is recorded at a recording angle essentially corresponding to the preset value, may be temporarily stored, and may be used for comparison to reference images.
In the simplest case, a frontal recording angle is established as the single preset value, upon reaching the frontal recording angle, a driver facial image is recorded, this driver facial image is temporarily stored and used for comparison to reference images.
In accordance with exemplary embodiments of the present invention, driver facial images are exclusively compared to reference images which have essentially the same recording angle. In the above-mentioned simplest case, the frontally recorded driver facial images are therefore exclusively compared to frontally recorded reference images.
Good recognition performance is ensured in general by the comparison of driver facial images and reference images having essentially equal, ideally frontal recording angles. To further increase the reliability of a method according to the present invention for facial recognition and/or to ensure the ability to perform such a method, the following embodiments and refinements are provided.
According to various advantageous embodiments of a method according to the present invention, multiple preset values are established for recording driver facial images. Depending on the embodiment of the present invention, either all or only a part of the recorded driver facial images are subsequently temporarily stored, subsequently all or only a part of the temporarily stored driver facial images are in turn used for comparison to reference images.
Because a method according to the present invention is to be executed with as little interaction as possible, i.e., without an instruction to the operator in regard to his head positioning or orientation, it may not be predicted whether a preset value for the recording angle will actually be achieved. Therefore, driver facial images having suboptimal recording angles may be initially stored, but not use these later for comparison to reference images if, at a later time, driver facial images may be recorded and temporarily stored which may be evaluated better, i.e., are better suitable for performing the comparison to reference images at a higher reliability level. In this way, computing outlay for unnecessary comparison operations may be saved, but the possibility is retained of starting a facial recognition on the basis of the suboptimal driver facial images if needed.
In order to save additional memory space in a temporary memory for temporarily stored driver facial images, a lower number of driver facial images than were established as preset values may be temporarily stored. As a first procedure, the temporary storage or even the recording of driver facial images at suboptimal preset values may be omitted if, at an earlier time, driver facial images which may be evaluated better were able to be recorded and temporarily stored. In addition, temporarily stored suboptimal driver facial images which are already temporarily stored may be overwritten in the temporary memory by driver facial images which may be evaluated better.
Finally, a smaller number of temporarily stored driver facial images may result than the number of the preset values if the performance of comparison operations for facial recognition is begun when triggered by a specific event, such as the expiration of a timer, although a driver facial image was not yet able to be recorded for every preset value.
The sequence of overriding or replacing driver facial images temporarily stored in the temporary memory may be controlled, for example, in that preset values are each assigned a priority and temporarily stored driver facial images may be replaced by driver facial images recorded at a later time, whose preset value is assigned a higher priority.
In a comparable way, the selection of which temporarily stored driver facial images are used for comparison may be priority-controlled. For this purpose, separate priorities may be established or the priorities for the driver facial images recorded for temporary storage may be used.
Establishing the number of preset values, the preset values themselves, and their priorities, but also the establishment of the number of temporarily stored driver facial images and the number of driver facial images used for comparison may be performed at the beginning of a method and/or may be adapted to the altered situation in the course of the method, in particular after the recording or temporary storage of individual driver facial images.
Other method rules, according to which the recording, temporary storage, and analysis of driver facial images are to be performed, may be implemented in connection with the present invention.
Because a complete databank having reference images of all possible drivers of a motor vehicle from all possible recording angles may not always be assumed, the method rules to be implemented are expediently defined oriented to the distribution of the recording angles of the available reference images. For this purpose, the recording angles of the reference images must also be known and assigned thereto.
The use of multiple temporarily stored driver facial images for comparison with reference images may have various reasons as a function of the method rules used as a basis.
Firstly, the cause may be an incomplete databank of reference images. For example, the databank may not have reference images of all possible drivers of the motor vehicle for the recording angle A or the recording angle B, but at least one reference image from one of the two recording angles for every possible driver is included. In this case, a driver facial image having the recording angle A and a driver facial image having the recording angle B would preferably be used for the comparison.
In addition, to increase the reliability of a method according to the present invention, it may be advisable for multiple driver facial images from different recording angles to be compared with a reference image of the same possible driver and for the comparison results to be linked to one another. In the simplest case, a linkage may comprise selecting the comparison result having the largest or smallest correspondence. Alternatively, any arbitrary form of linkage, mathematical filtering, or statistical analysis (e.g., calculating the mean value or median) of the individual comparison results may be performed.
A method according to the present invention is based on the assumption, which is especially applicable in a motor vehicle, that a target person, the driver of the motor vehicle here, at least temporarily orients his head in a specific direction, which essentially corresponds to the travel direction, within a finite time span. A head orientation in the travel direction is already favored by the orientation of the driver seat even in the time before beginning travel, but after entering the motor vehicle. Therefore, if a camera is attached in the motor vehicle in such a way that a specific recording angle results in the event of a facial normal line of the driver oriented essentially in the travel direction, it is thus ensured that a driver facial image may be recorded at a corresponding specified preset value within a finite time. This condition is fulfilled in many modern motor vehicles by a camera belonging to a device already provided in the motor vehicle, which is not primarily used for image-based driver identification. The occurrence of all recording angles which closely surround the recording angle existing in the event of head orientation of the driver in the travel direction is also to be expected at high probability due to the natural head movements of a driver.
A further advantage of the present invention, which results therefrom, is that typically no request must be given to the driver to produce a specific recording angle by his seat position, or head and/or body posture.
In order to nonetheless be able to perform an identification of the driver in exceptional situations, according to a refinement of the present invention, after expiration of a predefined time span or upon the occurrence of a specific event, if not all driver facial images required for performing the facial recognition at a sufficient reliability level are available, a request is given to the driver to support the driver identification by assuming a specific seat position, or head and/or body posture.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

Method for image-based driver identification in a motor vehicle

Bayerische Motoren Werke Aktiengesellschaft


A position controller including a position transmitter (9) and a control unit (13). The position transmitter detects the actual position of an actuator (7). The control unit (13) is arranged in an ignition-proof enclosure that is separate from the housing of the position transmitter (9). The interface (18) between the control unit (13) and the position transmitter (9) as well as the position transmitter (9) itselfxe2x80x94which comprises a magnet (10) and a magnetoresistive sensor (50)xe2x80x94have an inherent electrical safety design.

The invention relates to a position controller, particularly for a drive-actuated valve, with an inherent safety design.
European Publication EP 0 637 713 A1 discloses such a position controller for a drive-actuated valve. The valve is installed in a pipe and controls the passage of a medium by way of a corresponding stroke of a closing element that interacts with a valve seat. A pneumatic drive is connected, by a push rod, with the closing element. A lever engages with the push rod and acts on a potentiometer, which functions as a position transmitter of the position controller. The potentiometer detects the actual position of the actuator. A control unit of the position controller compares this actual position with a predefined desired position. As a function of the determined deviation, the control unit generates an actuating signal to control the pneumatic drive. The desired value is predefined for the position controller through a normalized signal, e.g., a 4 to 20 mA interface or a digital field bus message. Thus, the role of the position controller is to convert the predefined desired value of the actuator position into a pneumatic pressure signal that is supplied to the pneumatic drive and results in a corresponding position of the push rod.
In addition, flap valves are known in the art in which the opening angle of a rotary valve is detected by means of a rotary potentiometer. In this case, a position controller generates an actuating signal for a rotary actuator that controls the rotary valve.
Slide potentiometers, because of their simple and inexpensive construction, are frequently used for position detection. Their advantage is that they produce a usable electrical actuating signal in a relatively simple manner with low power consumption. For instance, a 10 kxcexa9 potentiometer operated at 3 V consumes a maximum of 300 xcexcA. The stroke or rotary movement of the actuator is applied to the potentiometer""s axis of movement via corresponding add-on parts, e.g., a rotary lever with a switchable gear drive, and the component voltage detected by the potentiometer is transmitted to the analog input of an analog or digital control unit. The detection range of the angle of rotation for rotary actuators is typically 120xc2x0 maximum. For linear actuators, typically the detection range is 15 mm maximum. The linear motion can also be converted into an angle of rotation of 120xc2x0 maximum by means of a conversion mechanism.
In many areas of process and power technology, the fault-free operation of a plant depends on the flawless functioning of the control valves used. Downtimes of plants or plant parts caused by component failures significantly reduce the production capacity and the possible utilization of the plant. Thus, reducing downtimes and increasing system reliability are essential goals for efficient plant operation.
Due to their construction, the electromechanical slide potentiometers, which are frequently used for rotary or linear position detection, have drawbacks regarding their long-term stability because of wear and oxidation of the contact paths as well as because of their vibration fatigue limit. After prolonged quasi-static operation, their sliders tend to stick. Due to mechanical wear, the sliders and the resistive coatings eventually wear or their quality changes as a result of aging and oxidation. In electromechanical slide potentiometers, the rotary or linear motion is transmitted by means of a continuous shaft. Suitable encapsulation against environmental influences is therefore very costly and in itself is susceptible to aging and wear.
European Patent EP 0 680 614 B1 discloses a device for detecting an angular position of an object. The sensors described in this patent specification are based on the giant magnetoresistive (GMR) effect and consist of alternating magnetically hard and magnetically soft metal layers. These layers are each only a few atoms thick and are sputtered onto a silicon substrate. The resistance of the sensors greatly depends on the direction of a magnetic field acting on them. A GMR sensor is thus very well suited to detect a change in the angular position of a magnet.
Electropneumatic position controllers are frequently used in areas where the atmosphere can change into an explosive gas mixture. Here, it must be ensured that no risk arises from any of the possible operating states of the position controller. For this purpose, the occurrence of an ignition spark must be either excluded by suitable means or ignition of the atmosphere in the environment of the position controller must be reliably prevented.
One object of the invention is to provide a position controller, particularly for a drive-actuated valve, which is distinguished by its improved interference immunity and its inherently safe design, while being inexpensive to produce.
To attain this and other objects, according to the principles of the present invention, and according to one formulation, the a novel position controller, for a valve (2) actuated by a drive (6), having an inherent safety design, includes: a position transmitter (9) that detects the actual position of an actuator (7), and a control unit (13) that compares the actual position with a predefined desired position and that generating an actuating signal, wherein the position transmitter includes a magnet (10) and a magnetoresistive sensor (50), and wherein the magnet and sensor are rotatable or displaceable relative to one another in conjunction with a movement of the actuator (7), wherein the control unit (13) is arranged in a flame-proof enclosure that is separate from a housing of the position transmitter (9), and further wherein an interface (18) of the control unit (13) to the position transmitter (9) as well as the position transmitter (9) itself have an inherent electrical safety design.
The invention has the advantage that an inherently safe design of the position controller is realized at relatively low production costs. High investments for protecting the operating voltage, which would be incurred in a position controller with an inherent electrical safety design not having an ignition-proof enclosure, are avoided due to the flame-proof housing of the control unit. For the position controller, it is sufficient to use an inexpensive plastic housing. There are no increased ignition protection requirements regarding the electrical connection between the control unit and the position controller. The control unit is mechanically and thermally decoupled from the actuator. Mechanical vibrations and shocks, as well as high or low temperatures, of the plant are thus not transmitted to the control unit. With an appropriate encapsulation of the position controller, it is possible to use the unit in a chemically loaded atmosphere or in an explosive environment because of the dual protection achieved. The position controller, which is located outside the housing of the control unit, is advantageously mounted to the actuator even on small drives or under extreme loads that are due, for example, to mechanical vibrations, shocks or extreme temperatures. The position controller then is electrically connected to the control unit at low cost. The control unit is mounted at some distance, e.g., on a mounting tube or a similar mounting aid, from the position controller and then connected thereto by an electrical cable connection, Further the control unit is connected with the pneumatic drive via one or two pneumatic lines.
The invention further obviates the drawbacks of conventional potentiometers, since it uses a contactless potentiometer that comprises a magnet and a magnetoresistive sensor. The novel position transmitter provides the exact actual position of the actuator in either a dynamic or a static case. A non-linearity of the position transmitter""s output signal, which is minor in any case, is readily compensated. Between the magnet and the magnetoresistive sensor, a partition can easily be installed for encapsulation and, thus, protection against environmental influences. Therefore, the position transmitter is very rugged and insensitive to dirt and a harsh environment. The magnet is easily mounted outside the sensor housing on a linear or rotary actuator such that its magnetic field lines act on the magnetoresistive sensor through the housing wall. An evaluation circuit is readily integrated in the sensor housing. This evaluation circuit generates a voltage proportional to the angle of rotation, or the linear path, of the magnet by way of the change in resistance of the magnetoresistive sensor. Thus, the evaluation circuit supplies, to a control unit, a signal that corresponds to the actual position and is immune to interference.
A minimum distance between the magnet and the sensor is easily kept to prevent damage to the magnetically hard layers, especially in a GMR sensor, since in this sensor type the strength of the magnetic field may not exceed 15 kA/m. The contactless principle of the novel position transmitter eliminates the problem of a scratching or sticking slide potentiometer. This contactless principle offers advantages in applications where the potentiometer is exposed to continuous vibrations. It is also advantageous in the quasi-static case where the potentiometer position remains unchanged over a long period of time, and where there is a risk that the slider of a slide potentiometer would dig into the resistance layer and possibly get stuck there due to control instability in the system. If the magnet forms the moving part of the position transmitter, which is coupled with the actuator, it couples the actuating movement into the magnetoresistive sensor through its magnetic field, without requiring any mechanical duct. By corresponding add-on parts, an exact rotary or linear motion of the moving part is ensured in a simple manner.
If the magnet is designed as a permanent magnet, a particularly simple structure results, since the magnet does not require a power supply, and thus does not increase the current consumption of the position transmitter.
An advantageous clear increase in the resistance of the magnetoresistive sensor results if a so-called anisotropic magnetoresistive sensor is used. When the magnetization of the layer is rotated relative to the current direction of a measuring current flowing through the layer of the sensor, there is a change in the resistance in this type of sensor, which can be a few percentage points of the normal isotropic resistance. This ensures a sufficiently high signal-to-noise ratio of the measurement signal.
Using a so-called giant magnetoresistive (GMR) sensor has the advantage that the change in the resistance is independent of the field strength within a wide range, and is only sensitive to the direction of the magnetic field. This directional dependence of the resistance resembles a cosine function, and is therefore nearly linear within a wide range.
Advantageously, the same sensor construction can be used for installation, in both rotary actuators and linear actuators, without requiring any structural changes. For this purpose, the GMR sensor is arranged in the area of the edge of a housing in such a way that the same sensor can be positioned to detect a relative rotational movement at least approximately on the axis of rotation of a magnet that is provided for this case, and to detect a relative shift jointly with a magnet that is provided for this case in a plane that extends substantially perpendicularly to the aforementioned axis of rotation. The distance between the sensor and the housing wall facing the magnet is preferably about 5 mm. This ensures that the required minimum distance between magnet and sensor is met. Since the sensor can be used in both rotary and linear actuators, the costs of logistics and warehousing are reduced because only one GMR sensor type is required.
Improved measurement accuracy in case of temperature fluctuations is obtained by arranging a temperature compensation circuit in the housing of the GMR sensor. To obtain particularly good temperature compensation, the bridge resistance of the GMR sensor is simultaneously used as a measurable resistance for the temperature compensation circuit. This completely eliminates problems of thermal coupling between the measuring resistor and the GMR sensor.
Advantageously, the GMR sensor is arranged on one side and the temperature compensation circuit on the other side of the same printed circuit board. As a result, the components of the temperature compensation circuit, the housing of which is typically larger than the component housing of the GMR sensor, do not need to be arranged between the GMR sensor and the exterior of the position transmitter housing that faces the magnet. Therefore, the components of the temperature compensation circuit do not influence the spacing between the GMR sensor and the exterior of the position transmitter housing. This makes it possible to keep a small distance between the upper edge of the component housing of the GMR sensor and the position-transmitter housing exterior.
Precise positioning of the magnet relative to the GMR sensor can easily be achieved by providing a centering aid on the housing of the GMR sensor to adjust the relative position of the magnet in relation to the sensor during installation. This positioning aid is configured as a molded part that is placed on the magnet, removed again after installation, and that is inserted into an opening on the housing of the GMR sensor in a positive fit during installation. After the magnet and the GMR sensor have been attached, the molded part is removed.
A mechanically positive-locking configuration of the moving part and the sensor housing ensures the spatially correct positioning of the magnet and the sensor. The connections of the two parts to form a complete position transmitter can be non-positive, i.e., wireless. Alternatively, the position transmitter can be constructed as a complete, mechanically integral, position transmitter block, which comprises the moving part with magnet, GMR sensor and evaluation electronics. Such a position transmitter ensures a defined distance between the magnet and the GMR sensor. In principle, active evaluation electronics that are completely isolated from the moving part, both mechanically and electrically, make possible robust and interference-free position transmitter electronics in miniature form that are screened in a simple manner against electrical as well as magnetic interference. The magnet itself requires no mechanical duct through a partition to the housing of the GMR sensor and is located together with the GMR sensor in a common screened chamber for protection against electrostatic and electromagnetic interference. For applications in areas that are subject to extreme interference, a corresponding external screen, which also encloses the magnet, can be constructed as an add-on component if required.
Other advantages of the novel position controller include its: readily integratable protective circuits; wide supply voltage tolerances; minimized external interference through integrated screens and EMI filters; minimized temperature influences with low supply current; minimized and stably reproducible hysteresis as a function of the angle of rotation between magnet and GMR sensor; and field strength.
The minor hysteresis fluctuations and the minor non-linearity, resulting from manufacturing tolerances of the GMR sensors, are irrelevant for the application as a position transmitter in a position controller. If the position controller is intended to output the actual position, as information to additional components of a system, the output signal is easily corrected and actively filtered corresponding to the known linearity and hysteresis characteristics of the individual GMR sensor. For this purpose, if required, the specific correction data of the GMR sensor is stored in a microcontroller of the position controller. For simplified correction of linearity and hysteresis errors, it is sufficient to determine and store five basic sensor-specific characteristic values, which are recorded under standard conditions. These basic values are located, for instance, at the points of the maximum change in the slope of the curves. For a more precise correction, all the characteristic curves can be stored with the desired resolution in a serially readable memory medium supplied with the GMR sensor and assigned to the GMR sensor by an identification key. The content of the memory medium is loaded, for instance, into the microcontroller upon installation of the GMR sensor.

Position controller for a drive-actuated valve having inherent safety design