A system, method and computer program product for identifying spam in an image, including (a) identifying a plurality of contours in the image, the contours corresponding to probable symbols; (b) ignoring contours that are too small or too large; (c) identifying text lines in the image, based on the remaining contours; (d) parsing the text lines into words; (e) ignoring words that are too short or too long from the identified text lines; (f) ignoring text lines that are too short; (g) verifying that the image contains text by comparing a number of pixels of a symbol color within remaining contours to a total number of pixels of the symbol color in the image, and that there is at least one text line after filtration; and (h) if the image contains text, rendering a spam/no spam verdict based on a contour representation of the text that which appears after step (f).

1. Field of the Invention
The present invention relates to identification of text in graphical images, particularly images that are suspected of being SPAM, and particularly SPAM-images with text that has been deliberately altered to defeat OCR and binary signature methods of SPAM detection.
2. Description of the Related Art
SPAM emails have become a veritable scourge of modern email systems. It is estimated that as much as 60-80% of Internet email traffic today is of a SPAM nature. SPAM, in addition to being annoying and wasteful of the time of the recipient, places a considerable burden on large email service providers and on corporate networks. For a regular user, the cost of SPAM that gets through is a few clicks that it takes to delete the offending message. For large-scale email providers, such as Google, Yahoo, Microsoft, as well as for large corporations that have their own server-based solutions for SPAM filtering, handling SPAM is a problem that needs to be solved on an industrial scale. For example, such large mail service providers need to filter millions of SPAM messages every hour.
A phenomenon observed recently is the increasing professionalization of SPAM generators. Many of the techniques used by SPAM generators closely mirror and borrow from the techniques used by many professional virus writers. At any given moment millions of computers connected to the Internet are zombified. In other words, these computers spew out vast numbers of SPAM emails, even though the owners of these computers are unaware of this fact.
Although in the early days of the SPAM epidemic it was possible to filter SPAM by looking for keywords, such as "Viagra," "Hoodia," "free offer" and so on, modern SPAM has evolved far beyond such simple and easily filterable examples. Today it is common to find SPAM embedded in images, which are themselves embedded within the body of the email or sometimes as an attachment to an otherwise innocuous email. The problem of filtering image-based SPAM presents a difficulty to the anti-SPAM software vendor, because filtering images generally requires a dramatically greater investment in hardware resources, compared to filtering simple text-based SPAM. Also, for large email service providers and corporate email servers, such SPAM filtering needs to deal with the SPAM more or less on-the-fly or within at most a few seconds, and it would be unacceptable if the SPAM filters delayed receipt of the email by significant time.
Image-based SPAM has thus far defied an effective solution primarily for two reasons. One is that SPAM generators have quickly learned to defeat signature-based methods of SPAM detection. If a known SPAM message (for example, a known SPAM GIF or a JPEG) is bitwise-compared to a suspect image, then by randomly changing a handful of bits in the images, the image remains virtually unchanged to the human observer but has a different signature (if only by a handful of bits). For example, where three bytes are used to represent each color pixel, changing only one bit of one pixel of a large image would be undetectable to the naked eye, but nonetheless such an image would be treated as having a different signature by the signature method of SPAM detection. Any changes in the background of the image, the color of the background or the letters, distributing random "blotches" or "spots" in the background of the image and so on, all combine to defeat the signature-based method for detecting SPAM in images.
Another way to detect image-based SPAM is through optical character recognition (OCR). The OCR-based methods have two primary drawbacks: first, they are very resource intensive and are difficult for use in email systems that process large numbers of such emails per unit length of time. The second problem is that the accuracy of OCR systems is significantly less than 100%, raising the prospect of a false positive detection of a message which in fact is actually not SPAM.
In the industry, a false positive is generally regarded as a greater evil than letting through some number of SPAM messages, since very often an email falsely identified as SPAM by the SPAM filter will never be seen by its recipient, or, at best, it would be seen much later by the recipient. Additionally, just as spammers have learned to defeat the signature method of SPAM detection, some techniques that attempt to defeat OCR-based SPAM detection techniques have become available. They include writing text not in a straight line, but using wavy or curved lines, addition of noise to the image, spacing the letters in the words such so the words could not be recognized by OCR software, writing some letters at an angle, etc.
An example of a multi-stage method for analysis of raster images is described in Russian Patent No. 2234734. In this patent the first stage is a preliminary text identification using a less exact method, and then using a more exact object identification for those objects that are left unidentified in the image. In the first stage the image is segmented into regions, tables, text fragments, text lines, words and symbols, and in the second stage the segmentation is further defined, using additional available information.
A similar principle is described in Russian Patent No. 2251151, where different objects in the image are divided into levels, based on the degree of complexity, such as a symbol, word, text line, paragraph, table, region. Each object is then associated with a particular level and the connections between objects of different levels and of the same level are then identified. Then a hypothesis is formulated regarding the properties of the various objects, which is later corrected, based on various image attributes.
Both of these methods essentially lack an identification of text elements in the image, which makes the processing of such images in real time a relatively difficult task.
U.S. Patent Publication No. 2004/0221062 describes a method where in order to identify contents of the image, a preliminary visualization of the image is done in a first format, and afterwards the message is transformed into a purely symbolic format, so that to filter out decorative components of an image, prior to text analysis. U.S. Pat. No. 7,171,046 also describes certain aspects of text identification in images.
U.S. Patent Publication No. 2005/0281455 describes a method of processing images and text in the images using a neural network. U.S. Pat. No. 6,470,094 describes a general localization methodology for text in images, where, as a symbol, several adjacent pixels are used, which, in turn, are combined into words.
U.S. Pat. No. 6,608,930 also describes identification of text in video images. In this patent, a first color is separated out, to enhance the contrast, which is further enhanced using a 3×3 map. Random noise is then removed using median filtration. The edge of the image is identified using an adaptive threshold, and then edges are removed from the image, so that portions of the image are deleted where there is no text, or where text cannot be reliably identified. Pixels that are close to each other are then combined into a single symbol, and then adjacent symbols are combined into words and then text lines. However, the method described in this patent is relatively calculation-intensive, and has not found substantial popularity.
Accordingly, there is a need in the art for an effective method of identifying text in images and an effective message of SPAM detection in emails that include embedded or attached images.

System and method for identifying text-based SPAM in rasterized images


A discharging container including a laminated bottle having a delaminatable layer is designed such that it can be manufactured through reduced processing steps. The present discharging container has the ambient air inlet and the ventilation hole. The inlet is formed solely in the outer layer and always kept open. The ventilation hole is formed solely in the outer layer and normally closed with the closing member or the inner layer. The inlet may be formed in a peripheral wall of the outer layer's body part and the ventilation hole may be formed in the mouth part of the bottle.

The Patent Laying-Open Gazette No. Hei. 4-267727 discloses a multi-layered container designed such that ambient air is inhibited from entering the container through a mouth while allowing its content to be discharged by the pumping action of an inner and outer layers. This container consists of a bottle and a cap, wherein the bottle is composed of the impermeable inner layer and the squeezable outer layer, with the cap being attached to the mouth part of the bottle. The inner layer can be readily delaminated from the outer layer in which at least one ventilation hole is formed such that the ambient air can communicate with a space between the layers. A check valve is incorporated in connection with the ventilation hole. The cap has a discharging outlet and a further check valve cooperating therewith.
Therefore, the inner layer will spontaneously shrivel as quantity of the content decreases, with the ambient air flowing into the space through the at least one ventilation hole so that only the outer layer can restore and always maintain its normal configuration. Its content remains satisfactory in quality, from the beginning to end of use, without being adversely affected by ambient air or external light beams.
The multi-layered container in the prior art has a film tag adhered in part to the rim of the ventilation hole, and the tag larger than the hole is disposed inside the outer layer so as to serve as a valve body in a ventilation valve. Such a kind of ventilation valve will allow air to flow only inwardly into the container from outside. When a user grips the container having a decreased amount of content left therein, the ventilation hole will be closed with the valve body due to an increasing inner pressure between the layers so as not to allow any amount of air to leak out from the interlayer space. Thus, such a depressed outer layer will compress air present between the layers, thereby causing the compressed interlayer air to press in a centripetal direction the inner layer to be capable of exuding the content out of the container to the very end.
The prior art method may comprise the steps of preliminarily blow molding or thermally forming the outer layer that has the ventilation hole formed therein, and subsequently integrating it with the inner layer. However, such a method requires so many steps as raising manufacture cost of the discharging containers and lowering yield thereof.
Therefore, an object of the present invention is to provide a discharging container having at least one ventilation hole but lacking in any valve body in connection therewith, nevertheless allowing ambient air to flow into the interlayer space and ensuring exhaustion of the liquid content. Thus, the invention aims at simplifying a structure of the container and lowering its manufacture cost.


Print information that has been generated by a first device is submitted to a second device and a print job is started (S101). Whether a failure has occurred on the side of the first device during the submission of the print information is detected (S102). In accordance with the detection made, it is determined to abort, suspend or resume processing of the print job that is currently being submitted. In accordance with the determination made, abort, suspension or resumption of processing is reported to the second device, which receives the print information, as notification of control of the print job (S105, S107, S109). This printing control method is such that if processing of print information is suspended owing to occurrence of a failure, the source (the first device) that submits the print information reports suspension to a remote device (the second device) that is the destination of the print information. It is possible to exercise control so as to resume print processing in response to elimination of any failure.

When print information that has been generated at the submitting source of a print job such as a host computer is subjected to print processing by a printer remotely connected via a network, the printer exchanges print information with the host computer and executes the prescribed print processing. If the source (a host computer in this case) submitting a print job develops a failure while the print job is being submitted to the host computer and, as a result, processing for submitting the print job can no longer continue, this processing is suspended without notifying the printer of such suspension.
Assume that when a print job is being submitted to a network-connected printer, the source submitting the print job develops a failure and the submission of the job is suspended. If in such case the print job is suspended without notifying the printer to which the print information is to be submitted, the processing of the print job continues being executed on the printer side. Since this print job cannot be completed normally, a condition arises in which the processing of other ensuing print jobs cannot be executed. The result is a decline in operating efficiency.

Print processing method, printing control system and storage medium therefor


A method for forming a relaxed semiconductor layer (12) includes forming a strained semiconductor layer on a substrate (11). The strained semiconductor layer has a different lattice constant than the substrate (11). Without exposing the strained semiconductor layer to an oxidizing ambient, the strained semiconductor layer is relaxed using thermal stress.

This invention relates, in general, to semiconductor processing and more particularly, to methods for forming strained heterojunction semiconductor devices.
Strained semiconductor heterostructures are useful for a wide variety of device applications where a narrowed bandgap can improve device performance. For example, in heterojunction metal oxide semiconductor field effect transistor (MOSFET) devices, a strained channel region enhances carrier mobility within the channel. In strained silicon channel regions, the strained silicon layer typically is formed on a substrate of greater lattice parameters than that of silicon. A relaxed silicon-germanium substrate is a suitable material because of its compatibility with silicon processing.
One reported approach to forming a strained silicon channel layer involves growing a silicon layer on an as-grown relaxed or unstrained SiGe layer. The relaxed SiGe layer is formed by first growing a graded Si.sub.1-x Ge.sub.x layer on a silicon substrate where x increases from 0% to 30% over a thickness of about 1.5 microns. Next, a 1.0 micron layer of Si.sub.0.7 Ge.sub.0.3 is grown over the graded layer followed a thin Si.sub.1-x Ge.sub.x layer where x decreases from 30% to 0% over a thickness of about 0.03 microns. This approach has several disadvantages including a high epitaxial film cost because it takes approximately 6-8 hours to grow the different layers. Additionally, this approach results in a high concentration of threading dislocations because of the thick epitaxial layers.
Accordingly, methods are needed for forming heterojunction devices having strained layers formed on relaxed layers with low levels of defects. It would be of further advantage for these methods to be cost effective.

Method for forming a semiconductor device having a heteroepitaxial layer


Excessive latencies and power consumption are avoided when a large number of leaf nodes (LNs) contend simultaneously to join a time slotted channel hopping wireless communication network having a root node (RN) interfaced to LNs by one or more intermediate nodes (INs). A first plurality of shared transmit/receive slots (STRSs) is allocated for at least one IN, and a second plurality of STRSs is advertised for use by contending LNs, where the first plurality is larger than the second plurality. When a LN joins, its STRSs are re-defined such that most become shared transmit-only slots (STOSs) and no STRSs remain. The numbers of STRSs allocated to INs may vary inversely with their hop counts from the RN. One or more STOSs may be added for each of one or more INs in response to a predetermined network condition.

The following documents are incorporated herein by reference:                IEEE STD 802.15.4; and        IEEE STD 802.15.4e.
FIG. 1 diagrammatically illustrates a simplified topology of a typical conventional wireless communication network operating in compliance with IEEE 802.15.4e, which is an amendment to the IEEE STD 802.15.4 radio communication protocol specification. This amendment specifically targets MAC protocol level modifications to enhance the performance of devices using IEEE 802.15.4 radios. A specific IEEE 802.15.4e MAC operation is referred to as Time Slotted Channel Hopping (TSCH), which enables robust as well as low-power communication. Channel hopping provides robustness against interference. The time slotted and time-synchronized nature of the protocol allows for time-scheduled communication. The scheduled communication means that the devices need to be active only when required and in "sleep" mode otherwise. This provides low-power operation.
As shown, the topology of FIG. 1 has a hierarchical structure with a plurality of hierarchical levels. The network of FIG. 1 includes at 11 a central root node (RN) that controls the network and serves as a gateway to higher bandwidth networks. A Level 1 intermediate node (IN) at 12 interfaces between the RN and a plurality of Level 2 INs at 13, which each in turn interfaces between the Level 1 IN 12 and one or more leaf nodes (LNs) at 14. The wireless communication links illustrated between the various nodes of FIG. 1 are also referred to herein as communication hops (or simply hops), such that, for example, RN 11 is three hops away from each LN at 14.
TSCH uses a sequence of time frames that are each divided into a plurality of slots of time (time slots). In the IEEE 892.15.4e scheduling scheme, each node is allocated a shared slot and at least one beacon slot in each time frame. A beacon slot is used by the RN 11 to transmit a beacon packet that contains the transmit/receive schedules of nodes in the network. Beacon slots are also used for time synchronization. The shared slot is a shared transit/receive slot (STRS) in which a node may either transmit or receive. New nodes attempting to associate with (join) the network contend for access to the STRS, and a successfully contending node transmits a network association request in the STRS. The STRS is the same interval of absolute time for each node of FIG. 1. The STRS is also used to convey network maintenance information and traffic routing information.
The RN 11 uses the STRS to transmit an association response in reply to an association request received from a successfully contending node. As new nodes join the network, they receive respectively corresponding association responses that allocate to them, in sequential fashion, respective pairs of dedicated slots. Each pair of dedicated slots consists of a transmit slot and a receive slot, both reserved for use only by the node to which they are allocated. If the joining node is an IN, the association response also allocates an additional beacon slot to the IN, to support the relay of beacon packets across the hops from the RN to the LNs.
A node operating in the network wakes up from sleep mode at every time slot and checks what function is to be performed. If none, it returns to the sleep state. The node listens in an active receive state during a beacon slot, an STRS and a dedicated receive slot, in order to ensure that no communication is missed. In a dedicated transmit slot, the node transmits as needed, or returns to sleep if it has nothing to transmit.

Adaptive time slot allocation to reduce latency and power consumption in a time slotted channel hopping wireless communication network


A method performed at a central entity includes (a) sharing a secret with a remote tenant server of one of a plurality of tenant organizations, the tenant server being configured to provide authentication services for accessing storage of the central entity, (b) receiving a storage request from a remote client device, (c) extracting an identification of the tenant organization from a core portion of the request, (d) selecting the shared secret of the identified tenant organization, (e) cryptographically combining the core portion and the shared secret to generate a preliminary signature, (f) performing a computation using the preliminary signature and a body portion of the request to generate a test signature, the body portion including the core portion and an object identifier, (g) comparing the test signature with a signature from the request, and (h) permitting the client device to access an identified object only when the comparison is positive.

Storage providers maintain large amounts of data storage for a multitude of users. These storage providers typically utilize authentication protocols in order to ensure that only authorized users can access the storage and that the authorized users only access portions of the storage that they are permitted to access. In order to access storage, a user may send a storage request to the storage provider signed with a signature created using a secret shared between the storage provider and that user. In order to authenticate a user for any given access attempt, the service provider verifies the identity of the user by making sure that the request is signed with the proper shared secret. The storage provider then allows access based upon an access policy for that user.
In some systems, a storage provider may rent storage space to tenant storage providers. These tenant storage providers are each responsible for initially registering each user with the storage provider. Then, a user is able to access the storage as described above.

Secure and anonymous distributed authentication


An anti-noise headset device and a sound processing method thereof are provided. The anti-noise headset device includes an audio receiving module and a control module. The audio receiving module is configured to receive several audio signals in several periods. The control module is electrically coupled to the audio receiving module. The control module is configured to store the audio signals received from a first period to an Nth period as sound data. The control module compares the audio signal received in an (N+1)th period with the sound data so as to generate a relevance value, N is an integer larger than zero. When the relevance value is smaller than a threshold value, the control module filters out a portion of the audio signal received in the (N+1)th period, in which the portion of the audio signal received in the (N+1)th period is relevant to the sound data.

Technical Field
The present disclosure relates to an anti-noise headset device. More particularly, the present disclosure relates to an anti-noise headset device for adaptively filtering out noise.
Description of Related Art
Usually, the conventional anti-noise headset device is configured to isolate the user from audios totally. Although the user can hear no noise by wearing the conventional anti-noise headset device, the user is unable to hear other sounds, too. However, in some occasions, it may result in an accident if the user is totally isolated from the received audios. For example, in the construction site, the user can be prevented from noise by wearing the conventional anti-noise headset device. However, when an emergency event happens, the user is also unable to hear the alarm immediately.
Moreover, the user also fails to talk with others when the user is isolated from noise by wearing the conventional anti-noise headset device. Since the use of the conventional anti-noise headset device is inconvenient and limited, an improved anti-noise headset device is provided. In the improved anti-noise headset device, some noise data are built-in previously. When the user wears the improved anti-noise headset device, it can filter out noise corresponding to the built-in noise data. Therefore, the user can hear other audios when the user is isolated from noise.
However, the use of the improved anti-noise headset device is still limited. For example, noise data must be built in the improved anti-noise headset device previously before the user wears it so that the improved anti-noise headset is able to filter out noise. Moreover, the built-in noise data is not adapted in every environment. In other words, the improved anti-noise headset device is able to operate only in some special occasions. When the environment is changed, the improved anti-noise headset device is unable to filter out noise corresponding to the changed environment. For example, the anti-noise headset device for aircraft includes built-in engine noise data. Therefore, the anti-noise headset device for aircraft is not adapted in the construction site or other noisy environments. Accordingly, the use of the improved anti-noise headset device is still inconvenient and limited.

Anti-noise headset device and sound processing method thereof


The casing of a centrifugal pump is borne by a second section of a composite frame, and such second section has legs resting on or being embedded in a foundation. A first section of the frame carries a motor for the pump and is carried by the casing. In addition, the two sections of the frame are connected to each other to partially surround and confine the casing against radial expansion in response to increasing internal pressures, and the sections are held against each other so that they are maintained under an initial stress which opposes elastic deformation of the casing. The weight of the motor is transmitted directly to the foundation.

The invention relates to improvements in pump-motor assemblies, especially in assemblies wherein a motor is used to drive a centrifugal pump. More particularly, the invention relates to improvements in frames for pump-motor assemblies and to improvements in means for and in methods of installing pump-motor assemblies in such frames.
The casings of centrifugal pumps are often subjected to pronounced internal pressures. In order to ensure that the casing of a centrifugal pump will be capable of standing such stresses, it is customary to provide the casing with external reinforcing ribs or to increase the thickness of the casing. Such expedients are also resorted to if the casing is large. These undertakings are intended to prevent expansion of the casing in the event of pronounced internal pressures, to prevent such extensive deformation of the casing that the casing is likely to come in contact with the impeller or impellers and/or to prevent the development of cracks in certain regions of the casing, particularly in the region of the so-called spurs. Reference may be had, for example, to German Auslegeschrift No. 1 135 765 of Klaus (published Aug. 30, 1962). A drawback of the proposal of Klaus is that the pump casing is very expensive, even if the casing constitutes a casting. It is necessary to make complex and expensive cores and patterns which are utilized to carry out the casting operation.
Another prior proposal to reinforce the casing of the pump in a pump-motor assembly or aggregate is disclosed in British Pat. No. 911,769 granted Nov. 28, 1962 to Jonkopings Mekaniska Werkstadts Aktiebolag. This publication discloses a frame which resembles a tripod having three legs resting on a base and supporting the motor of the pump-motor assembly from below. The casing of the pump is suspended from the frame and is disposed between the legs. The patented assembly is bulky and the frame is incapable of ensuring that the pump casing will indeed stand pronounced internal pressures. The reason is that the frame merely serves as a means for propping the motor from below and for releasably holding the pump casing in suspended condition.


A vending machine for lottery tickets includes an exterior housing for access by a purchasing customer and a secure interior within which is mounted a plurality of dispensing containers to dispense the one or more tickets as selected by the purchasing customer. A plurality of separate holders for printed ticket information are arranged in an array, each with a purchase switch and an information switch actuable by the customer. Graphic information is provided on a video display screen controlled by a control unit within the housing arranged to control the dispensing of the selected tickets and to display on the video display screen graphic information relating to a ticket in response to information switches actuated by the customer. The graphics on the screen can be actuated in response to a motion sensor detecting the presence of a customer. The screen serves also as a display screen for the authorized operator and thus can be moved to be viewed from outside or inside a door. The printed cards are illuminated by a row of LEDs. Complex graphics for the screen can be provided on a memory stick plugged into a USB port on the input interface.

Ticket vending machines for example those manufactured by Gtech Corporation of Rhode Island (previously under the name Interlott Technologies Inc of Cincinnati, Ohio) Pollard Banknote Limited of Winnipeg Canada (previously under the name American Games Inc. of Council Bluffs, Iowa) generally include an exterior housing which contains and secures the tickets and payment receptacle and which is accessible by customers for actuating switches on the housing for dispensing selected lottery tickets.
The lottery tickets are contained within separate containers within the housing each of which has a dispensing unit operable to dispense a ticket from a selected container in response to the actuation of the switches by the customer.
The control of the dispensing is effected by a control unit within the housing which is responsive to the actuation of the switches by the customers and responsive to the receipt of payment from the customers for dispensing the tickets.
Instant win lottery tickets can be provided either as scratch-off tickets or as pull tab (otherwise known as break-open) tickets. While the two above types of tickets are different in many respects both in regard to the manner of manufacture and in regard to methods of validation and control, the present invention is intended to be directed to both types of lottery tickets and the term "lottery ticket" as used herein is intended to cover both types and other types of lottery tickets which require dispensing in the same or similar manner as the above types.
Generally lottery tickets of the scratch off type are manufactured in a continuous strip which is then fan-folded for convenient supply. Generally break open type tickets are manufactured in individual ticket pieces which are then formed into a stack and dispensed one at a time from the bottom of the stack.
Machines for dispensing scratch off type tickets in fan folded form and machines for dispensing break open type tickets in stacked form have been available for many years. The construction, arrangement and operation of these machines is well known to one skilled in the art and is incorporated herein by reference.
In addition specific arrangements of dispensing arrangement proposed for use in a dispenser for the fan folded scratch off tickets are shown in U.S. Pat. No. 6,714,838 (Scrymgeour) and U.S. Pat. No. 6,712,253 (Hargrave) which are commonly owned with this application. The first of these shows an arrangement for entering data concerning the book of tickets to be introduced into the machine for dispensing by the machine and the second shows a dispensing arrangement for feeding an upper end of the strip of tickets to a feed system which acts to burst the perforations between each ticket and the next as each ticket is dispensed in turn. The construction and arrangement of these dispensing devices is incorporated herein by reference.
The dispensing machines are generally maintained on the premises of a retailer so that the retailer is charged with the responsibility of filling the containers as necessary to maintain a continuous supply without shortages which would potentially reduce sales. It is necessary therefore for the containers to be refilled on a periodic basis, either shortly after a container has become empty or in order to anticipate the container becoming empty. The service person therefore is required to check the inventory of a container and to top up the supply within each container which may be empty or approaching empty.
The apparatus includes a control unit which monitors the inventory and controls the dispensing of the tickets in response to the manual actuation of the switches by the customers and in response to the submission of suitable payment by the customers.
Furthermore the control unit controls the operation of the dispensing unit of each container so as to forward the ticket to be dispensed to the required dispensing location. In regard to the scratch off type tickets which are generally supplied in a continuous strip, it is generally desirable to effect a bursting of the perforations between each ticket and the next so as to allow an individual ticket to be dispensed into a chute. This avoids any possibility of a customer improperly tearing a ticket or being able to pull an extended number of tickets from the supply. In order to effect the bursting action, it is necessary for the dispensing unit to have information concerning the length of the ticket from its leading edge at the previous perforation line to the trailing edge at the next perforation line so as to move the perforation line to the bursting position and so as to dispense the ticket. In regard to the break open type tickets which are conventionally supplied in individual ticket form, it is also necessary for the control unit to have information concerning the length of the ticket in order to ensure that the ticket is properly dispensed.
The marketing of lottery ticket involves generating attractive tickets of different game types to successfully convince the customer to purchase the particular game.
In addition it is conventional to supply to the customers a selection of tickets of different prices so the customer may choose particular tickets not only based upon the attractiveness of the game but also upon the amount of money which the customer chooses to pay.
In order to provide the customer with an appealing array of tickets from which to purchase, the dispensing machine generally although not necessarily includes a number of containers which can vary depending upon the particular size of dispensing machine required for example from 12 dispensing containers up to 24 dispensing containers. Each container generally therefore will be filled with a different game for selection by the customers. Generally the game selection remains constant so that it is necessary only for the service person to maintain the containers properly filled by adding into each container a fresh supply of the tickets associated with that container. However in addition it also necessary on occasion to change the game associated with a respective container when older games are cancelled and new games are brought in to replace those older games. Lotteries release 50 to 80 new tickets per year and they want all of them to be in the ITVM while on sale in the marketplace, so the service reps will have to "change out" some containers or bins every few weeks.
The dispensing machine also should provide attractive graphics and information which assist in informing the customer of the games available and assist in completing the sale of such tickets. It is known therefore to provide a video screen on the machine which provides information on the tickets available. Commonly such screens are of the "touch screen" type so that the customer makes a selection and purchase by touching the graphic of the ticket selected. An example of a machine of this type which is proposed as one alternative for use with lottery tickets is shown in U.S. Pat. No. 5,408,417 (Wilder) issued Apr. 18th, 1995.
An early example of a vending machine for lottery tickets which suggested the incorporation of a screen is that disclosed in U.S. Pat. No. 5,222,624 (Burr) issued Jun. 29th, 1993 where there is proposed that the tickets be displayed on a screen as an array of the tickets available. This proposal was suggested in replacement for the main proposal of the patent where the tickets themselves are visible through windows in the front of the housing. The display is thus limited to the array of tickets available and even suggests that the ticket of the array which is selected for dispensing have the graphic thereof move to simulate the dispensing.


Some implementations described herein provide techniques and apparatuses for an extreme ultraviolet (EUV) radiation source that includes a backsplash-prevention system to reduce, minimize, and/or prevent the formation of tin (Sn) build-up in a tunnel structure of a collector flow ring that might otherwise be caused by the accumulation of Sn satellites. This reduces backsplash of Sn onto a collector of the EUV radiation source, increases the operational life of the collector (e.g., by increasing the time duration between cleaning and/or replacement of the collector), reduces downtime of the EUV radiation source, and/or enables the performance of the EUV radiation source to be sustained for longer time durations (e.g., by reducing, minimizing, and/or preventing the rate of Sn contamination of the collector), among other examples.

An extreme ultraviolet (EUV) radiation source includes a collector, which includes a curved mirror that is configured to collect EUV radiation and to focus the EUV radiation toward an intermediate focus near an intermediate focus cap (IF cap) of the EUV radiation source. The EUV radiation is produced from a laser produced plasma (LPP) that is generated by exposing droplets of tin (Sn) to a CO2 laser. The Sn droplets are generated by a droplet generator (DG) head, which provides the Sn droplets into a vacuum chamber to an irradiation site where the Sn droplets are irradiated by a focused laser beam.

Semiconductor processing tool and methods of operation

Taiwan Semiconductor Manufacturing Company, Ltd.


In a conventional hologram, a photographic film records the interference pattern of monochromatic light, scattered from an object (20) to be imaged, with a reference beam of unscattered light. Illumination of the developed film with a replica of the reference beam then creates a virtual image of the original object. Molecular resonance may be used to record an interference pattern between light signals that arrive at different times, and with this technique create a hologram (10') with time resolution. Using a time reference pulse (16) as a "light shutter", holographic images may be recorded selectively, according to the time taken by light travelling from the object to the hologram. This method may be used to image an object obscured by a light-scattering medium.

Attempts to illuminate an object embedded in or hidden by a light-scattering medium are often difficult to accomplish reasonably. For example, while X-rays may be employed to image bones, the high energy of X-rays limits their usefulness due to potential damage to tissue. Also, in the detection of breast cancer in women, present mammography requires exposure of breast tissue to X-rays; this procedure, repeated several times over the course of a woman's man's life, has its own risks of creating cancer, even though the benefits may outweigh the risks.
As a general rule, light, though of a lower energy and thus not as damaging to tissue, cannot be used to image such objects. This is due to the fact that most of the light going through a light-scattering medium, such as flesh, is scattered; only a small fraction of the incident light is not scattered.
Suppose one wanted to view a light-absorbing object embedded in or behind a light-scattering medium. If it were possible to see an image of such an object, the image would appear as a shadow-gram of the object. However, in general, the light scattered by the medium fills in the shadow of the object produced by the unscattered light, thus making the object invisible.
A key fact is that the portion of light that is not scattered emerges first from the light-scattering medium, while the scattered light emerges later. One could use this fact to produce an image of the object, if one could somehow provide a shutter to separate the light that is scattered from that which is not. Note, however, that the time resolution of such a shutter, which depends on the sample thickness, must be on the order of 10.sup.-12 seconds, or 1 pico-second (ps). Such a requirement eliminates mechanical shuttering, which cannot physically respond in such short times.
One approach provided by the prior art is to use a Kerr shutter. Such a device incorporates a cell of a liquid, such as CS.sub.2, positioned between two polarizers, set orthogonal to each other so that light incident on one polarizer does not pass through the other. When an intense beam of light is directed onto the liquid cell, the intense beam disturbs the polarization of light passing through the cell, so that light incident on the one polarizer can now pass through the other polarizer. When the intense beam is turned off, the liquid relaxes back to its original state, and the light is again blocked by the pair of polarizers. The typical relaxation time for this method is about 1 ps.
Another approach in the prior art is known as "light-in-flight" (LIF) recording by holography, developed by N. Abramson and co-workers. In this method, a short coherence length pulse is split into two parts and geometrically ar
ranged to both illuminate an object and scan a reference beam across a holographic plate so that holographic images can be formed in a continuous time sequence across the plate. A related approach, called "chrono-coherent imaging" (CCI) is an adaptation of LIF recording to medical imaging. Unlike LIF recording, which is done in air, medical imaging applications have a liquid medium and do not emphasize reflectivity of solid objects. The imaging modality is differential reflectivity or absorption, and it involves the effects of shadows from differential absorption (or differential scattering). In both cases, wavefronts interfere in successive times to produce a hologram that, when viewed along its length, recreates the time sequence.
Like the Kerr shutter, the LIF and CCI techniques also isolate the first-arriving light, and provide jitter-free, low-power, high-pulse-repetition-rate, two-dimensional imagery, with a temporal resolution virtually the same as the pulse duration. However, the LIF-type configuration does not necessarily produce the best spatial resolution, especially with short pulse durations in the femtosecond domain.
A variation of the holographic recording method is to replace the photographic recording plate by a high-resolution electronic camera. The camera records the hologram, which can then be sent to a computer for analysis; see, e.g., Chen et al, Optics Letters, Vol. 16, No. 7, pp. 487-489 (1991).
Another method for isolating the first-arriving light is to use the process of second-harmonic generation; see, e.g., Yoo et al, Optics Letters, Vol. 16, No. 13, pp. 1019-1021 (1991). In this method, a short pumping pulse of frequency .omega. and photons from the scattering medium (also at frequency .omega.) are made to overlap in a frequency-doubling crystal. If photons from the two light sources reach the crystal at the same instant, then the crystal will emit a photon of frequency 2.omega. in a particular direction. This frequency-doubled light is easily detected. (If the photons do not reach the crystal at the same time, then, in principal, no frequency-doubled light is observed.) The pump pulse is adjusted to arrive at the crystal at the same time as the unscattered light from the scattering medium, so that the amount of frequency-doubled light is proportional to the amount of unscattered light reaching the crystal. The sample is scanned, point by point, and the amount of frequency-doubled light is recorded for each point in the sample. In this way, a two-dimensional image of the unscattered light is laboriously constructed. A disadvantage of this scheme is that the entire image cannot be acquired at the same time; instead, the sample must be slowly scanned, point by point.
A need remains for a technique for storing and producing images of an object obscured by a light-scattering medium, using light.

Method of imaging through a scattering medium using coherent light


The present invention relates to a non-invasive device for measuring physiological processes. More particularly, it concerns a device that can be applied externally to the body of an animal or human to detect and quantify displacement, force, motion, vibration and acoustic effects resulting from internal biological functions. Specifically, an inexpensive device is disclosed that is compact, light, portable and comfortable, and operates satisfactorily even with imprecise location on the body, ambient noise, motion and light.

The present invention relates to a non-invasive device for measuring physiological processes. More particularly, it concerns a device that can be applied externally to the body of an animal or human to detect and quantify displacement, force, motion, vibration and acoustic effects resulting from internal biological functions. Specifically, an inexpensive device is disclosed that is compact, light, portable and comfortable, and operates satisfactorily even with imprecise location on the body, ambient noise, motion and light.
Traditionally, non-invasive gauging of physiological processes in vivo has been accomplished either with large, complex and expensive techniques such as X-ray, tomography, magnetic resonance and ultrasound, all of which demand the skills and infrastructure of a medical institution, or with simpler, more portable equipment. In the latter category, devices employing superficially attached electrophysiological electrodes (electrocardiogram (ekg), electroencephalogram (eeg), electromyogram (emg), electrooculogram (eog)) are prevalent, but require skill and surface preparation for proper electrode attachment and cause skin irritation with prolonged use. Small portable xe2x80x9clightxe2x80x9d devices using optical, ultraviolet and infrared spectroscopic and absorption techniques are also implemented widely based on the availability of miniaturized electromagnetic sources, detectors and support electronics. However, these devices are quite susceptible to interference from movement and/or ingress of ambient light. Motion, displacement, vibration and acoustic sensing techniques have also been developed extensively but have yet to see widespread adoption because their inherent sensitivity to movement, location and noise makes it difficult to interpret signal changes in a normal ambulatory environment. Such techniques range from commercially available, simple, passive actigraphy devices to complex servo-driven systems that react instantaneously to each force or displacement as it is generated by the body. The actigraph is typically a casing attached to the body containing a suspended accelerometer element that responds to all magnitudes and frequencies of motion. During physical activity, it therefore reflects the level of effort being exerted overwhelming any other physiologically derived signals, and during quiet rest periods it becomes sensitive to the body""s internal xe2x80x9cballisticsxe2x80x9d such as breathing, tremor, and heart and arterial pulsation. The servo driven devices are generally invoked to quantify physiological parameters such as blood pressure where the force applied to the actuating element can be used as a measure of the force deriving from the biological function. Typically, these devices are quite bulky, demand external power or compressed air supply and require extensive computation capability. In between these extremes lies a spectrum of devices as described below, covering a range of complexity, accuracy and cost, and varying in effectiveness at combating extraneous signal pick-up. Because of the pre-eminent importance to modern medicine of evaluating cardiovascular function, emphasis has been placed on devices that measure heart rate, arterial pulse profile and blood pressure in the review that follows.
Commercially available devices exist which measure heart rate and provide the output on a wrist-mounted display similar in appearance to a wrist-watch. However, none exist which operate continuously and autonomously without ancillary equipment and without requiring some operation to be performed by the wearer.
1. Chest Band Pick-ups
A large number of products are available commercially from manufacturers like Acumen, Bodyguard, Cardiosport, Cateye, Polar, Performance, Sensor Dynamics, Sigma, Sports Instruments and Vetta, which sense the electrical activity of the heart through electrocardiogram type electrodes mounted in an elasticated chest band. The resultant electrical spikes are then identified and transmitted to a display that may be mounted anywhere within the range of the telemetered signal xe2x80x94in a wrist-watch type devise, a bicycle handlebar mounted readout, or a custom computer display on a piece of exercise equipment. However, even on far forward bicycle handlebars the signal can be lost. A typical device is described in U.S. Pat. No. 5,690,119 to Pekka.
While the devices typically provide steady and reliable readings, they are best suited to use for brief periods during exercise rather than as a continuous long-term or all-day monitor. In addition, the readings are affected by other users nearby utilizing similar heart rate monitors, electromagnetic radiation interference, particularly from power lines and motorized equipment. Accordingly, they typically will not work in an automobile, near TV""s and computers, and on certain types of exercise equipment using electric motors and video screens. While less constraining than an ear clip or finger stall with their associated wires, the chest band takes time to put on under clothing and is a physical encumbrance to the exerciser. In addition, it typically only functions when good electrical contact is established to the skin, either by moistening with water or through sweat during vigorous exercise. During very vigorous activity such as mountain biking the chest-band will often slip down from the optimum pick-up location.
2. Handlebar Pick-ups
Certain types of exercise equipment, such as treadmills, stair-steppers, etc, are outfitted with electrically conducting handlebars that serve as crude electrocardiogram leads. The change in gross position of the cardiac dipole during the course of each beat is manifest as a measurable shift in surface potential between the right and left side of the body and can be picked up at the gripping surface of each hand.
Although this provides feedback while the exercise equipment is being used, all readings are lost when physical contact with the equipment is broken.
3. Ear Lobe Pick-ups
Some exercise equipment and heart rate monitors come with a small infrared transmitter (a light emitting diode is a typical example) and detector that clips onto the ear-lobe and picks up the fluctuation in IR transmission through the ear as the capillaries fill with blood and then drain during the cardiac cycle. The pulse data is hard-wired from the sensor to a display mounted on the wrist or other convenient location. A typical commercially available product of this type is the Cateye PL-6000.
In addition to being uncomfortable, and awkward (because a wire has to be run from the detector on the ear to a visible display), these devices are prone to interference from movement and changing ambient lighting conditions. The slightest head motion causes changes in the amount of IR radiation detected, hence the apparent pulse rate, due primarily to the light that leaks in around the edges of the detector window.
U.S. Pat. No. 5,490,505 to Diab et al. describes such a device, typically configured as a pulsoximeter on the finger or ear with two different wavelength LED""s shining through the tissue to enable an attenuation measurement to be made after propagation through or reflection from the medium. Pulse rate is determined from the periodic attenuation associated with the increase and decrease in arterial flow during a pulse cycle. However the resultant plethysmographic waveform is readily overwhelmed by motion because movement exerts a strong influence on the dynamics of venous blood flow and hence venous blood attenuation of the LED wavelength. Accordingly, the patent describes complex and involved signal processing to recognize the true signal and extract it from exercise-generated noise.
U.S. Pat. No. 4,867,442 to Matthews describes an exercise aid configured as a sweatband around the head with IR or piezoelectric sensors on the ear to pick up pulse. However, the patent provides no enabling disclosure to overcome the motion induced artifacts which would obscure the pulse signal during exercise.
4. Finger Stall and LED Window Pick-ups
While finger stalls are specifically discussed here, the same shortcomings are found with a number of devices used on other parts of the body where there is adequate superficial blood flow, such as the ear, the finger or forehead. Devices requiring fingers or thumbs to be placed over LED windows on the face of a watch are discussed below.
Two devices, the Nissei PU-701 and the Elexis FM-135, are available commercially, which operate on the same principle as the above-described infrared ear-lobe sensors, except that the IR radiation is sent through and received from the fingertip encased in a lightproof finger stall. The resultant information is displayed on a wrist-mounted monitor.
As with the ear-clip, these devices are susceptible to motion and light interference, have external wiring, and are cumbersome and unappealing to wear either during exercise or for routine pulse monitoring during inactive parts of the day. While the lightproof finger stall gives superior results to the LED window types described below, the readings become inaccurate while gripping any object such as a handlebar.
U.S. Pat. No. 4,807,639 to Shimizu describes a watch with either an LED and phototransistor window on its face or a removable finger stall wired to the electronic circuits in the watch case. In either case, a finger is disposed simultaneously over both the LED transmitter and the phototransistor detector (for the finger stall version, both are housed within the stall) such that light reflected by the finger surface, and hence modulated by pulse is detected and counted at the receiving phototransmitter. Because the device only works when the user is motionless and the finger is carefully and properly positioned, the watch is equipped with bar displays corresponding to inadequate readings thereby guiding the user to reposition the finger or move into more favorable ambient lighting conditions.
5. Hand Held Devices
Both ECG type and IR detection type pulse measurements can be accomplished with devices that are held in the hand. One such instrument, the Sportline 390 is held in one hand while the thumb of that hand is placed over an IR window exploiting the same principle as described above for the ear lobe and finger stall sensors. Even though this only occupies one hand, this still constrains most types of activity and the hand must be held very still during a measurement.
Free-standing devices have been developed which operate on the same electrocardiogram principle as the above referenced handlebar pick-ups. In a device made by Pulse Time, the instrument is held in one hand thereby making contact with one electrophysiological electrode and the other hand is brought across to contact an electrically separate part of the device thereby measuring a potential difference across the body during the cardiac cycle. The watches with contact plates described below operate on this same principle. The Biosig Instruments Instapulse series of devices use electrophysiological electrodes embedded in bars and handles that are gripped with both hands. In the Heart Rate 1-2-3E, the thumb of each hand is applied to a different electrode surface on a hand-held unit.
Clearly, these devices are only suitable for intermittent spot checks on pulse because they only work as long as both hands are being used to make the electrical contacts. This is incompatible with exercise and most other types of activity particularly since there is a delay of several seconds after contacting both electrodes before the pulse is displayed.
1. Watches with LED Windows
Watches have been developed and made commercially available by companies such as Casio and Innovative Time, where the pulse is measured by holding a thumb or fingertip over a small LED mounted in a watch face. The IR from the LED penetrates the superficial capillaries of the finger and the amount of IR reflected back to a co-located detector changes as the volume of blood in the capillaries varies during the course of a pulse.
These instruments have all of the disadvantages common to IR based devices as described above for the finger stall and ear lobe types, such as extreme motion sensitivity, and taking several seconds following application of the finger before a pulse reading is registered. They cannot be used during exercise where hands and arms are involved, and are only useful for occasional discontinuous readings because both hands are needed to take a measurement. In addition, the instructions issued with these watches reflect numerous practical difficulties with the measurement because of sensitivity to ambient lighting conditions, sweat and body hair.
2. Watches with Contact Plates
Working on a similar principle to the above described Handlebar Pick-up pulse monitors, watches have been developed by Seiko, Advanced Body Metrics and Physi Cal Enterprises, for example, which have a small metal plate on the watch face insulated from the metal backing of the watch which rests against the wrist. The user brings across a finger from the opposite hand to touch the insulated metal plate thus setting up the usual two electrode electrocardiogram scheme with one contact as the fingertip and the other, the back of the wrist of the opposite arm.
As with the LED window watch, the device is impractical for continuous reading or measurement during exercise because both hands and arms are tied up by the measurement. In addition, there are electrical contact problems and hence readings become unreliable when the user""s wrist under the metal backing of the watch is hairy.
A device of this type is described in U.S. Pat. No. 4,938,228 to Richter where, in the preferred embodiment, the biosignal reflecting the pulse is generated by an electrocardiogram electrode on one wrist and another electrode on the finger of the opposite hand. Other proposed locations included any two well separated parts of the body of opposite polarity. Alternatives to the ECG electrode are microphonic, piezoelectric, photo-optical and capacitative types, but there is no enabling disclosure describing their implementation. In a non-clinical environment, the signal is confounded by movement, low signal to noise in certain individuals, and poor electrical contact to the skin. The patent therefore describes very complex and computationally intensive signal processing and pattern recognition schemes (which incorporate a time-consuming learning cycle before any pulse data can be registered) to overcome these extreme difficulties encountered in trying to extract clean pulse data from non-medical, non-chest mounted ECG leads. After applying the computational methods of the invention, 50% of subjects still gave unsatisfactory readings during exercise, suggesting the need to slow or stop the exercise or abrade or wet the skin.
The above-described shortcomings of wrist pulse displays which require ancillary equipment or which require manual intervention, have spawned a large number of attempts to develop a device that is continuous reading, autonomous and fully self-contained on the wrist. While many have been invented and patented, none have been successfully developed into commercially viable products. Some of the more promising attempts and their shortcomings are reviewed below.
1. Pressure/Displacement Sensors
In U.S. Pat. No. 3,807,388 to Orr, a heartbeat rate monitor or personal pulse indicator is described employing a sensor that is either a xe2x80x9cpressure sensitive resistorxe2x80x9d or a xe2x80x9cpressure sensitive transistorxe2x80x9d. Beyond these generic terms, no further description is provided for implementing these sensor types to ensure high signal to noise, to avoid signal loss with wrist movement or to adapt to a wide range of input signal strengths. For either sensor type, the sensing element is shown embedded in, and protruding from, the inner surface of a wrist strap to react to pressure changes at the surface of the wrist during the course of a pulse. To counter random movement of the strap, the sensor is held firmly in one position on the wrist and not allowed to slide by virtue of a stabilizing frame that also protrudes from the strap beyond the circumference of the sensor element. The sensor elements shown to be very small in comparison to the width of the strap, and from the figures, measures approximately {fraction (1/10)} inch in diameter.
In U.S. Pat. No. 4,120,296 to Printz, a pulsimeter is described for indicating the average heart beat rate using a sensor adapted for flat application against the body, preferably at the wrist. The device merely uses a commercially available sensor, known as a Hewlett Packard digital plethysmograph model 14301A. From the drawings and method of application, the sensor appears to be about xe2x85x9cxe2x80x3 in diameter and thin enough to completely embed in a conventional watch-band ( less than {fraction (1/10)}xe2x80x3). There is no discussion of modification to the sensor or its implementation to improve signal to noise ratio, compensate for location specificity or to accommodate a wide range of input signal strengths.
In U.S. Pat. No. 4,009,708 to Fay, a pulse recorder is described, self-contained in a wristwatch type case. The sensor is either a microphone or a pressure sensor, approximately xc2xc-xe2x85x9cxe2x80x3 in diameter as shown in the figures, but no further description or implementation is provided to explain how practical issues are resolved, such as location sensitivity, signal strength changes and competition with noise signals. Moreover, the sensor forms part of the back face of the case and therefore bears on the upper surface of the wrist where there is very little acoustic or pressure activity occasioned by the pulse.
In U.S. Pat. No. 3,742,937 to Manuel, a self-contained, compact cardiac monitor is described for strapping on the wrist over the region where the radial pulse is normally detected. Two sensor mechanisms are described, both using a differential pressure detector scheme within a chamber of encapsulated low viscosity oil. The outer surface of the sensor is constructed of pliable silicone rubber which moves in response to the pulse and thereby displaces silicone oil in a centrally located pocket. In one case, a thin leaky silicon diaphragm with embedded strain gauges divides the encapsulated oil into two chambers. During the course of a pulse, the oil moves and deflects the diaphragm producing a measurable signal on the strain gauges. In the other case, the oil is divided into two sub-chambers by the flexible central conductor plate of a capacitor so that the capacitance of the circuit changes in response to oil movement during a heart beat. Overall dimensions of the silicone rubber enclosure are xc2xc-xc2xdxe2x80x3 in diameter and 0.1-0.2xe2x80x3 thick.
In U.S. Pat. No. 4,281,663 to Pringle, a physical fitness indicator is described utilizing a piezoelectric displacement sensor similar to a crystal phonograph pick-up attached to the wrist, throat or ear lobe. Although Pringle states that it is technologically feasible to house the whole device in a watch-type case with the sensor bearing on the radial pulse, no description of the sensor is provided, nor is there any discussion of how to overcome location sensitivity and motion artifacts. In addition, while the signal conditioning electronics and processing software identify and count pulses, no consideration is given to managing input signals with vastly differing magnitudes and signal to noise ratios.
In U.S. Pat. Nos. 4,331,154 to Broadwater and 4,307,727 to Haynes, a self contained wrist-mounted blood pressure monitoring system is described employing a very small diameter rod digging into the skin above the radial artery. The rod has a tiny piezoelectric crystal mounted on the end that engages with the skin to respond to the displacement pulse as a bolus of blood passes down the vessel. No attempt has been made to match the impedance of the hard ceramic crystal on top of the hard rod to the mechanical impedance of the physiology. A simple tensioning mechanism adjusts the length of the wrist band until the artery is flattened to half its initial diameter. In fact, it is likely that most of the motion produced by pulsation in the artery would be taken up in compliance of the band and mechanisms behind the piezoelectric crystal rather than getting coupled into the crystal itself.
2. Ultrasonic Devices
In U.S. Pat. No. 4,086,916, a cardiac monitor wristwatch is described with an ultrasonic transmitter and receiver in the wristband. The device registers movement of the outer surface of the radial artery by frequency difference between the impinging and reflected signals as the artery expands and contracts during a heartbeat. While the ultrasonic transmitter is power consuming and would therefore not appear suitable for continuous monitoring with a typical small watch battery power supply, it is claimed that the existing watch battery will suffice because the transducers are very directional and therefore efficient.
While numerous methods have been proposed for continuously and non-invasively measuring blood pressure as an alternative to the invasive arterial line, none have yet reached the point of widespread medical acceptance and commercial availability.
In the standard arterial line technique, a pressure sensor is inserted into the artery or into a contained volume of blood in free communication with the artery, and generates a signal that continuously and accurately reflects the blood pressure. However, the procedure is uncomfortable, expensive, consumes care-provider time and risks embolization, nerve damage, infection, bleeding and vessel wall damage.
The standard non-invasive device is the automatically inflating pressure cuff (applied over either the brachial or the radial artery), which can be uncomfortable with repeated use and only provides discontinuous sample readings at the time the device activates. The device typically requires 15-45 seconds to take a reading and, because it is occlusive, a minimum of 15 seconds must be allowed between readings to allow sufficient venous recovery. Also, frequent cuff inflations can produce ecchymosis and nerve damage under the cuff after extended periods of use. The oscillometric signal utilized by a cuff is also very sensitive to motion of the arm.
Another commercially available non-invasive blood pressure measuring device is the Finapres which employs photoplethysmography, e.g., as disclosed in U.S. Pat. No. 4,846,189 to Sun, U.S. Pat. No. 4,869,261 to Penaz and U.S. Pat. No. 4,406,289 to Wesseling, to interrogate the diameter of a blood vessel and correlate this to pressure. A small cuff containing an IR source and detector tuned to the wavelength for hemoglobin is inflated around a patient""s digit. After measuring the mean arterial pressure, from then on, the device adjusts the applied pressure to maintain the diameter of the artery constant (transmural pressure held at zero). As the patient""s blood pressure changes, this is then reflected in a change in the pressure that must be applied to hold the diameter of the artery fixed. This device has been found clinically unsatisfactory because changes in arterial diameter due to changes in arterial wall compliance (vasomotor tone) are falsely registered as blood pressure changes. In addition, the constant pressure is uncomfortable over extended periods of monitoring, and the peripheral blood pressure measured in a finger is not necessarily representative of central blood pressure, particularly if the vascular circulation is poor or there is peripheral vasoconstriction.
In U.S. Pat. No. 5,406,952 to Barnes, a wrist mounted device is disclosed for non-invasively measuring blood pressure, comprising a pressure/displacement pick-up with a piezoelectric sensing element mounted over the radial artery on the underside of the wrist. The piezoelectric element is a unimorph disk constructed from a 10 mil brass substrate with a 10 mil layer of piezoelectric ceramic deposited on its surface. The element is activated by a small diameter rod protruding from the device into the skin above the radial artery at one end and bearing on the center of the disk at its other end. The disk is suspended from a compliant circumferential ring of silicone rubber which diminishes the amount of energy transferred into the electroactive element. In principle, as a bolus of blood passes along the radial artery during a pulse, the artery expands, raising the skin and flesh above it and displacing the rod into the piezoelectric element. In practice, it would be very difficult to assure accurate and reliable positioning of the small diameter rod over the radial artery, particularly in view of lateral displacement of the radial artery as the wrist is rotated and repositioned. Accordingly, there would be an unacceptable amount of signal attenuation and even complete drop-out accompanying normal movement. To counteract this position-dependent effect and prevent motion artifact as the rod gets pulled against the skin, patentee uses an adhesive foam interface to hold the actuating rod exactly in place. However, the band used to keep the device on the wrist does not run over the sensor housing and therefore does not apply pressure to help keep the housing in mechanical contact with the wrist. In addition, the signal levels from this device would be extremely low and hence difficult to extract from noise because the unimorph disk configuration is relatively stiff and very little force is applied to it by the rod because of the small area of contact between the externally protruding end of the rod and the artery wall which provides the driving force. Another way of considering this is that the actuating rod is fairly difficult to move into and out of the plane of the disk and therefore is effective at resisting the motion of the artery wall. Accordingly, the flesh and skin expansion during each pulse will tend to xe2x80x9cside-stepxe2x80x9d the rod and instead expand into the neighboring tissue. To derive a blood pressure from the displacement signal, patentee uses a signal processing scheme that is totally independent of signal amplitude and instead relies on an empirically derived set of correlation factors applied to their pattern recognition and morphology analysis.
In U.S. Pat. No. 5,485,848 to Jackson, a non-invasive, non-intrusive, convenient and portable blood pressure measuring device is described based on sensing the user""s arterial wall movement. Although no details or implementation are provided, it is suggested that the sensing can be accomplished with an aneroid chamber, strain gage, optical motion sensor or hydraulic sensor. Absent such details, it is not clear how the devices would be applied to overcome signal to noise problems, widely disparate input signal levels and signal attenuation with position changes. The one sensor implementation that is described, utilizes a film of piezoelectric polymer embedded in the inner surface of a wrist band. Much attention is given to band tensioning and locking mechanisms in addition to automatically controlled motorized tension adjusters. Even with these measures, it likely that the signal to noise ratio would be inadequate for pulse measurement with this device, particularly as the signal became obscured by movement and other extraneous phenomena.
In U.S. Pat. Nos. 4,960,128 and 5,163,438 to Gordon, a film of piezoelectric Kynar is disposed over the artery to sense the pulse and transmit the signal over a 10 foot cable to a signal processing means. Because the film has inherently poor electromechanical coupling and is applied directly to the skin without any modification to match its mechanical impedance to the physiology under test, the example pulse trace is very noisy and must be integrated to smooth the curve and eliminate noise. Blood pressure is obtained by feeding the Kynar signal into a standard arterial line monitor after applying a correction factor to the signal amplitude. The correction factor is an empirical scaling value that depends on how much of a frequency shift there is between the frequency corresponding to the maximum amplitude (based on a Fourier transform) of the pulse in question and the initial calibration pulse. Signal processing is applied. There is no provision for motion or other noise compensation, or means to handle a wide dynamic range of input signal amplitudes.
In PCT Pat. No. WO 95/18564 to Kaspari, a piezoelectic film is disposed over the artery in question together with two outside elements whose output is summed and subtracted from the main sensor to minimize sensitivity to motion artifact. Blood pressure is determined by breaking down the measured pulse profile into all of its components (both phase and amplitude) related to different physiological functions and identifying those that correlate best with changes in blood pressure. Pattern recognition and neural networks are used to xe2x80x9clearnxe2x80x9d which features provide the best match to blood pressure during a xe2x80x9ctrainingxe2x80x9d phase on the patient. These features and empirical relationships are constantly updated based on calibration values from a non-invasive cuff. To shorten the training process, a historical database is developed on a large population of patients where blood pressure is measured continuously and invasively via catheter and compared side by side with the non-invasive piezoelectric signal to predetermine which features correspond best with blood pressure.
In U.S. Pat. No. 3,926,179 to Petzke, a tonometer is described comprising a bulky apparatus resembling a long thick rod applied orthogonal to the wrist above the radial artery. The rod is not suitable to be self-contained on the wrist because it incorporates a power-consuming servo-controlled pressure applying means to compress the artery to half its thickness and thereby maximize the signal strength and eliminate artifacts due to circumferential components of the arterial expansion. The sensor mechanism positioned at the center of the pressure applying piston is smaller in diameter than the artery under interrogation and comprises a flexible resilient diaphragm with a few tiny elements on its surface that expand and contract as the diaphragm flexes in response to the pulse. Since the electrical resistance of the elements changes as they are mechanically strained, a differential resistance between centrally and peripherally disposed elements provides a measure of the pulse amplitude. Because the sensor is so small, it would have to be very accurately placed and held in position, and the signal strength would be very susceptible to arm movement or rotation. No provision is made for rejecting motion artifacts.
Other tonometric devices are described in U.S. Pat. Nos. 4,269,193, 4,799,491 and 4,802,488 to Eckerle, U.S. Pat. No. 4,423,738 to Newgard, U.S. Pat. No. 5,033,471 to Yokoe, and U.S. Pat. No. 5,165,416 to Shinoda, and a commercial implementation is available through Colin Medical. This device uses a multielement piezoresistive sensor to pick up the amplitude of the pulse at the wrist and use this to follow blood pressure trends between oscillometric cuff readings. The sensing element is small compared to the artery and so will give readings that are very location dependent as the patient moves.
Another non-invasive technique uses pulse transit time (typically to the ear lobe and to the finger) to correlate with blood pressure, as disclosed in European Patent 0 443 267 A1 to Smith. The arrival time of the pulse at the ear and finger is measured by photoplethysmography at each location and used to calculate a change from the calibration pressure measured with a cuff. However, the technique does not compensate for changes in shape of waveform, and even small movements and noise cause relatively large errors in the delay time because the transit times are very short along major arteries.
PCT WO 95/28126 to Caro describes an active interrogation scheme for determining blood pressure by measurement of pulse wave velocity down the arm, whereby a small amplitude excitation signal (20-600 Hz) is superimposed onto the normal pulse profile using air pressure modulation in a cuff inflated on the forearm near the elbow. The combined pulse and superposed perturbation are received by a piezoelectric film over the radial artery and the resultant signal processed by analysis of phase relationships to separate out the three constituentsxe2x80x94the pulse, the perturbation and noise. Pattern recognition is used to ensure that a true pulse has been received. Blood pressure is determined from look-up tables based on both the velocity and phase of the superposed exciter wave. Values in the tables derive from statistical measurements taken on a representative population of patients. The piezoelectric receiving sensor is held in place with a second pneumatic cuff that also acts as a baffle to keep out external noise. A third pneumatic cuff is applied over the biceps in conventional fashion to measure a calibrating oscillometric blood pressure. In one alternative embodiment, the need for a calibration cuff is eliminated by including a second excitation signal on the pulse carrier wave. In another, the exciter and sensor are both located over the wrist. However, the device is not suitable to be self-contained on the wrist because of the computationally intensive signal processing and the need for bulky and power consuming inflation cuffs and regulators.
In U.S. Pat. No. 4,807,638, electrical bioimpedance measurements are made between two segments of body tissue to determine the pulse wave velocity.
Many previously described attempts to gage pulse and blood pressure rely on direct contact between a sensing element and the skin above an artery. While new classes of extremely pressure sensitive materials and devices are now available in forms that can readily be miniaturized to the configuration of an unobtrusive wrist sensor, none of these can meet the very exacting requirements of a wrist-mounted pulse sensor without significant modification, and incorporation into systems which accommodate the physiological variables and the motion and noise environment. Examples of these materials and devices include the elastomeric sheet material polyvinylidene difluoride (PVDF), semiconductor strain gages, pressure sensitive resistors and diodes (and their semiconducting counterparts), and piezoelectric crystals and composites. Many attempts have been made to sense pulse by interfacing these materials and devices directly to the body at locations such as the neck, forehead, wrist and thigh where arteries lie close to the surface of the skin. The following patents provide a good range of examples where the material or device is placed directly against the body at the point above the artery, either alone or as the outer surface of a contact pad in a more elaborate application mechanismxe2x80x94U.S. Pat. Nos. 4,784,152; 4,901,733; 4,947,855; 5,101,829; 5,131,400; 5,238,000; 5,439,002; 5,467,771; 5,497,779; 5,551,437; 5,515,858; and 5,509,423. In all cases, even though the sensing element is very sensitive, the pulse pressure wave manifest at the body surface is so subtle that the target signal is readily lost in or confused with noise and other environmental influences.
While some inventors have recognized the benefit of capturing arterial displacement signals over a broad area on the surface of the body and have provided relatively large contact pads to accomplish this end, these pads usually contain sensing elements in the contacting surface and therefore do not work satisfactorily for the reasons given in the preceding paragraph. However, the present invention preferably employs an inert (non-sensing) contact pad that acts through a mechanical load capture and transfer element which in turn activates the sensitive material or device. The inert pad responds to a displacement at any point on its surface and focuses the energy onto the sweet spot of the sensor. The prior art techniques introduce complexity into the system by attempting to achieve wide area pick-up by populating the contacting surface area of the pad itself with actual sensing elements. Any energy incident on the contacting surface area at a point not populated by a sensor is not detected by the device. An additional problem, as will be described below, is that this direct interfacing technique does not provide enough separation of the signal from the noise. In addition, new layers of computation and optimization are required to continually select the sensor with the best signal and/or weight inputs from the different sensors.
To avoid the above referenced problem of low absolute sensitivity to the pulse wave and high susceptibility to noise with techniques and devices that use direct contact sensing, techniques have been proposed that separate the two functions of contacting the body surface and sensing the displacement. For example, in U.S. Pat. No. 3,838,684, surface contact is effected with a fluid filled elastomeric bladder while the arterial motion signal is picked up remotely in the fluid through distortion of a central baffle plate which in turn actuates a capacitative displacement sensor or strain gages located on the plate. In U.S. Pat. Nos. 4,058,118, 4,409,983 and 4,561,447, the pulse is initially interfaced with a contact pad which then transmits the load to the center of a small beam with a strain gage or a beam of piezoelectric material, either crystalline, bimorphic or configured as a bender bar. While this arrangement is used in 4,058,118 to transfer pressure received over a gently contoured area of contact pad onto the center of a piezoelectric element, the pad is constrained to move only along the axis perpendicular to the plane of the piezoelectric crystal because it can only move within the fixed geometry of a piston and cylinder type arrangement. Automatic gain control circuiting on the signal input is employed, but the patent does not address signal susceptibility to mispositioning and motion. Accordingly, it is recognized that the device alone cannot combat the problem of noise and motion infiltration hence requiring that the device only be used during very quiet, stationary periods.
In U.S. Pat. Nos. 4,409,983 and 4,561,447, the same basic mechanism is used as above in U.S. Pat. No. 4,058,118, but soft cushioning material or springs are incorporated into the outer mounts for the piezoelectric or strain gage beam to dampen the structure and mechanically filter out high frequency noise. While patentees claim the resultant motion and noise pick-up are significantly diminished, the soft mounting feature greatly reduces the absolute sensitivity of the piezoelectric beam sensor. Because there is such a huge variation in arterial pulse signal strength, associated with individual differences, changes during the day, changes with limb position, changes with health and exercise, etc., the greatest possible absolute sensitivity of the sensing element is required to ensure that the entire dynamic range can be covered.
In Pat. No. 4,561,447, a single element sensor embodiment of the invention is described which is designed to be hand-held against the neck of a patient by a caregiver who can properly place the device over the carotid artery by lining up the cut-outs in either end of the sensor. Exact positioning is critical because of the particular actuating mechanism, where a presser portion is used to contact the body over an artery and an abutment portion transfers the load onto the center of a flexible beam incorporating a strain gage, mounted at its ends. The size of the presser portion is less than the diameter of the artery under interrogation since the presser portion fits within end slots (cut-outs) in the housing designed to accommodate the projection of the artery at the surface of the body. In addition, the direct spatial relationship of the presser and abutment creates inherent sensitivity to getting mis-positioned because it ensures that only those forces or displacements impinging directly on the relatively small area of presser surface are transferred to the measuring strain gage. This point is emphasized in the disclosure of two multi-element embodiments of the invention developed for the purpose of overcoming distortion associated with the sensor getting displaced in any way from its optimal position on the body. In one of these embodiments, the line of elements traverses the artery, thereby allowing one of the plural presser portions to be located within an area of the neck skin in which the pulse wave of the carotid artery can be detected as a sufficiently high level of electric signals without a distortion. In the other embodiment, the plural sensors allow detection of a pulse wave signal without a distortion which could be caused by misalignment of a detector or sensing device relative to the carotid artery when the detector has a single sensing unit.
The 4,561,447 patent also places great weight on high fidelity replication of the exact pulse profile and defines a distortion parameter that has to be kept below a certain level to satisfactorily meet the requirements of the invention. The principal factor controlling distortion is the depression pressure experienced at the actual sensing surface against the body. Accordingly, a highly compliant (elastic modulus as low as practicable) mounting material (foam, elastomer, springs, etc.) is introduced under the end-mounts of the sensing beam to ensure that the depression pressure remains within the optimal range while the actual application force from the user""s hand varies widely from very light to very strong application. When a high modulus mounting material is used, the depression pressure becomes too high, causing the pulse wave signal to be distorted.
The present invention has been developed in view of the foregoing, and to address the deficiencies of the prior art.
The invention described below is intended to provide a simple, inexpensive, compact and portable device for sensing physiological signals while overcoming the prior art difficulties of susceptibility to noise, motion, orientation (attitude of body member to which the sensor is attached) and inadequate dynamic range to cover the broad spectrum of actual input signals encountered in physiological measurements. To reduce the response of the device to force and acceleration associated with gross body movement, the sensing element, coupling mechanism, and its mounting structure are made extremely light and are all tightly coupled to the body surface at the point of attachment such that both the element and its mount receive the external motion equally and can therefore cancel it as a common mode in a difference measurement. Depending on the demands of the specific application, noise and motion effects are optionally further reduced through subtraction and filtering schemes based on the frequency content detected in a separate optional motion sensitive element or elements, common mode rejection employing another comparable optional sensor, or sensors, located away from the maximum physiological signal, or signal processing to extract recognizable physiological signal patterns from noise and motion artifact. Advanced detection and tracking electronics are used to span the very demanding dynamic range of sensitivity needed to follow signals as they vary widely from individual to individual, and within an individual with level of physical activity, time of day, state of health, limb orientation, etc. The dynamic range is also maximized through use of an extremely sensitive sensing member, firmly mounted with respect to the sensor housing and actuated with considerable mechanical advantage by the physiological process at a very sensitive point on the sensing member. Mechanical advantage is achieved by not placing the sensing member in the contact face of the device so that it can be actuated by a pressure amplification mechanism. Problems with loss, or decreased amplitude, of signal with misalignment from the ideal sensing location are minimized with a novel design of xe2x80x9cfree-floatingxe2x80x9d contact pad that interfaces to the body over an area that is broad enough to encompass most of the area of the body where effects of the physiological process in question are manifest. This interface not only conforms comfortably to the contour of the skin but responds in an essentially omnidirectional fashion to forces and displacements incident at any angle onto the outer face of the pad. While the pad is simply an inert mechanical collector of force and displacement, it couples via a mechanical transfer mechanism to a highly sensitive portion of a sensing member. Optionally, to ensure that device responds to the physiological process but not to unrelated noise or motion, the mechanical transfer mechanism is constrained to respond only in one axis directed towards the source of the physiological phenomenon and thereby reject any motions or forces the contact pad has picked-up in orientations away from this axis.
A specific use of the invention is as a non-invasive device for use on mammals including humans and other animals to sense blood vessel wall motion and blood vessel wall position, measure pulse rate and/or amplitude and shape of arterial pulse profile from which to derive blood pressure. The sensor and conditioning electronics of the device are also suitable for measuring parameters such as vascular wall compliance, ventricular contractions, vascular resistance, fluid volume, cardiac output, myocardial contractility and other related parameters.
To be configured for continuous use as a cardiovascular monitor, the sensor assembly is preferably made as light and compact as possible and applied with a band over a suitable artery on the body. Preferably, the device is made fully self-sufficient with sensor assembly, support electronics, power supply, processing and display all incorporated on the same band.
In a preferred embodiment, the device is non-encumbering and suitable to be worn continuously and to calculate and readout pulse and blood pressure continuously or as required. The device is sensitive to pressure/displacement signals of widely varying magnitude collected over a broad area on the underside of the wrist, and includes signal conditioning electronics that automatically normalize the signal level to facilitate digital processing and counting. Optional data storage and digital interfaces, such as a standard RS232 port or infrared communications link, may also be included to increase the versatility, appeal and usefulness of the device. For this embodiment as a wrist worn pulse counter, it is an aspect of the present invention to provide the following combination of features: no ancillary equipment (such as chest band, ear lobe clip, finger stall, equipment to hold, window or plate to touch) beyond the self-contained wrist device itself; convenient all-day comfort and portability, wearability; continuous ongoing measurement and display; no action or intervention required of the user to activate readings; insensitive to hair, sunlight, sweat; and cleanest possible sensor signal with highest fidelity replication of the motion of the arterial wall movement to minimize or eliminate the need for complex signal processing techniques, learning and pattern recognition.
These and other aspects of the invention will be more apparent from the following description.