In a first embodiment, a dynamic computer system security method and system using dynamic encryption and full synchronization between system nodes. A data record created by a source user is encrypted with an initial dynamic session key. A new dynamic session key is generated based upon a data record and a previous dynamic session key. A central authority is used to synchronize and authenticate both source and destination users with constantly regenerated dynamic authentication keys. In a second embodiment, a method of providing dynamic security authentication between wireless communication network nodes. An initial authentication key and an address are assigned to certain of the nodes. The address along with information encrypted by the initial authentication key is sent to an authentication server. The authentication server and node or nodes synchronously regenerate authentication keys based upon the initial authentication key. Secure handovers occur between nodes via an authentication key.

1. Field of the Invention (Technical Field)
The present invention relates to the field of wireless communication network security, more particularly to a dynamic authentication method and system for providing secure authentication amongst wireless communication network nodes.
2. Background Art
The fundamental objective of cryptography is to enable users to communicate securely via an insecure shared data communication channel or system environment, maintaining data integrity, privacy, and user authentication. Over the past century, various cryptography systems have been developed which require a great deal of time to break even with large computational power. However, if an intruder obtains the encryption key, the encryption mechanism, and probably the entire system security, is compromised and a new key is required.
In order to make an encryption system nearly impenetrable to an intruder, two strategies are commonly used: 1) a long encryption key, and/or 2) a complex encryption function. A key of length n bits has a 2n search space. Therefore, for large values of n an intruder needs to spend more than a lifetime to break the cipher. Also, simpler encryption functions provide a less secure encryption system. For instance, an encryption code that applies the logic XOR function is easy to decipher no matter how long the key length is. This is because the XOR operation is performed on one bit of data and its corresponding bit from the encryption key, one bit at a time. The deciphering approach of such simple encryption functions by an intruder is based on the divide-and-conquer mechanism. The intruder first deciphers individual key fragments, which is relatively uncomplicated to accomplish due to the simple linearity of the XOR function, then reconstructs the entire key once all of the individual fragments are obtained. It is more difficult to apply such a divide-and-conquer approach to break the key of a nonlinear exponential encryption function, such as used in the Rivest-Shamir-Adelman (RSA) system.
At present, there are two major cryptography system philosophies: 1) symmetric systems (static or semi-dynamic key), and 2) public key systems (static key). In symmetric systems, e.g., DES, AES, etc., a key is exchanged between the users, the sender and receiver, and is used to encrypt and decrypt the data. There are three major problems with symmetric systems. First, exchanging the key between users introduces a security loophole. In order to alleviate such a problem, the exchanged key is encrypted via a secure public key cryptography system. Second, the use of only one static encryption key makes it easier for an intruder to have an ample amount of time to break the key. This issue is addressed by the use of multiple session keys that are exchanged periodically. Third, and more importantly is the susceptibility to an "insider" attack on the key. This is referred to as the "super user" spying on the "setting duck" static key inside the system, where the time window between exchanging keys might be long enough for a super user, who has a super user privilege, to break in and steal the key.
In the RSA public key cryptography system, a user (U) generates two related keys, one is revealed to the public, deemed the "public" key, to be used to encrypt any data to be sent to U. The second key is private to U, called the "private" key, and is used to decrypt any data received at U, which was encrypted with the corresponding public key. The RSA cryptography system generates large random primes and multiplies them to get the public key. It also uses a complex encryption function such as mod and exponential operations. As a result, this technique is unbreakable in the lifetime of a human being for large keys, e.g., higher than 256 bits, and also eliminates the problem of the insecure exchange of symmetric keys, as in a DES system. However, the huge computational time required by RSA encryption and decryption, in addition to the time required to generate the keys, is not appealing to the Internet user community. Thus, RSA cryptography is mainly used as "one shot" solid protection of the symmetric cryptography key exchange.
In the RSA public key system, if a first user (UA) requests a secure communication with a second user (UB), the latter will generate a pair of encryption keys: public EB and private DB. An internal super user spy (S), with a helper (H) intruding on the communication line externally, can easily generate its own pair of keys, a public ES and private DS, and pass DS and EB to H. Then S can replace the public key EB with its own public key ES. Thus, all data moving from UA to UB will be encrypted using ES instead of EB. Now H can decrypt the cipher text moving between UA and UB using the private key DS, store it, and re-encrypt it using the original EB, in order for UB to receive and decrypt it without any knowledge of the break that occurred in the middle. Such an attack is typically called the "super-user-in-the-middle" attack.
Even though they are secure against outsider attack, both the symmetric and public key cryptography systems are still vulnerable to insider attacks. By obtaining the key at any time of a secure session, an intruder can decipher the entire exchanged data set, past and future. Further, a super user can easily steal a static symmetric key and send it to an outside intruder to sniff and decrypt the cipher text, particularly in the DES and AES systems.
A common way to protect a static encryption key is to save it under a file with restricted access. This restriction is not enough, however, to prevent a person with super-user privilege from accessing the static key in the host file. Even when keys are changed for each communication session, for example in the Diffie-Hufman system, there is a time window enough for the super-user to obtain the semi-static key. In most crypto systems, once the key is found the previous and future communicated data are no longer secure.
Various other attempts have been made to circumvent intrusion by outside users through encryption of communicated data. Examples of such methods include that described in U.S. Pat. No. 6,105,133 to Fielder, et al., entitled, "Bilateral Authentication and Encryption System;" U.S. Pat. No. 6,049,612 also to Fielder, et al., entitled, "File Encryption Method and System;" and U.S. Pat. No. 6,070,198 to Krause, et al., entitled, "Encryption with a Streams-Based Protocol Stack." While the techniques described in these patents may be useful in preventing unwanted intrusion by outsiders, they are still prone to attack by the super-user-in-the-middle.
Wireless communication networks are also prone to security breaches. The ability to provide mobile communications and broadband media services are two major requirements of modern telecommunication networks. The requirement to allow mobile communication devices, or "supplicants", to move between access points (APs), or base stations, while maintaining full, mutually-secure authentication makes mobility management one of the critical aspects of wireless communication. The rapid progress in wireless communication systems, personal communication systems, and "smartcard" technologies has brought new opportunities and challenges to be met by engineers and researchers working on the security issues related to new communication technologies.
Public-key cryptography offers robust solutions to many of the existing security problems in communication systems, however, excessive computational demands caused by on-line memory, code size, speed, etc. have made the use of public key cryptography limited, particularly on wireless communication systems. The implementation of public-key cryptography on server and client main platforms rarely causes problems due to the availability of high-speed processors and extensive memory space. However, in restricted hardware environments with limited computational power and small memory, such as in smartcards and mobile telephones, maintaining a secure environment is more challenging. Thus, the integration of public-key cryptographic techniques is often delayed or completely ruled out due to the difficulty of obtaining efficient, reliable solutions.
An industry standard describes the communication that occurs in wireless local area networks (LANs). The Wired Equivalent Privacy (WEP) algorithm is used to protect wireless communication from eavesdropping. WEP relies on a secret encryption key that is shared between a supplicant such as a laptop personal computer with a wireless card, and an AP. The secret key is used to encrypt data packets before they are transmitted, and an integrity check is used to ensure that packets are not modified in transit. The standard does not discuss how the shared key is established. In practice, most installations use a single key that is shared between all mobile stations and access points.
WEP uses the RC4 stream cipher encryption algorithm. A stream cipher operates by expanding a short key into an infinite pseudo-random key stream. The sender XORs the key stream with the plaintext to produce ciphertext. The receiver has a copy of the same key, and uses it to generate an identical key stream. By XORing the key stream with the ciphertext, the receiver yields the original plaintext. To ensure that a data packet has not been modified in transit, an Integrity Check (IC) field is included in the packet. To avoid encrypting two ciphertexts with the same key stream, an Initialization Vector (IV) is used to augment the shared secret key and produce a different RC4 key for each packet. The IV is also included in the packet. However, both of these measures are implemented incorrectly, resulting in poor security.
Ineffective WEP security leads to different types of intrusion, or attacks, by outsiders. For example, a passive eavesdropper can intercept all wireless traffic, until an IV collision occurs. By XORing two packets that use the same IV, the attacker obtains the XOR of the two plaintext messages. The resulting XOR can be used to make inferences regarding the contents of the two messages. The Internet Protocol traffic is often very predictable and includes a great deal of redundancy. This redundancy can be used to eliminate many possibilities for the contents of messages. Further educated guesses about the contents of one or both of the messages can be used to statistically narrow the field of possible messages, and in some cases it is possible to determine the exact contents of the message.
Another type of attack is also possible when using the WEP algorithm to secure communications. If an attacker knows the exact plaintext for one encrypted message, the attacker can use this knowledge to construct correct encrypted packets. The procedure involves constructing a new message, calculating the Cyclic Redundancy Check (CRC-32), and performing bit flips on the original encrypted message to change the plaintext to the new message. The basic property is: RC4(X) XOR X XOR Y=RC4(Y). This packet can then be sent to the access point or supplicant where it will be accepted as a valid packet.
Even though the WEP algorithm is part of the standard that describes communication in wireless LANs, the WEP algorithm has failed to protect wireless communication from eavesdropping and unauthorized access to wireless networks. This is primarily due to the fact that it relies on a static secret key shared between a supplicant and the wireless network.
In a first embodiment, the present invention alleviates the problems encountered in prior art communication network security, providing continuous encryption key modification, one key for each data record. New keys are generated from the previous key and data record, and are used to encrypt the subsequent data record. The key lifetime is equal to the time span of record encryption, which is too small for an intruder to break and a super-user to copy. The present invention also reduces computational overhead by breaking the complexity of the encryption function and shifting it over the dynamics of data exchange. Speed is also improved through the use of a simple XOR logic encryption function. A shuffling mechanism based on a dynamic permutation table, which is generated from the current session key, is coupled with the XOR logic operation, to strengthen the encryption function. The present invention also alleviates the "super-user-in-the-middle" attack. An intruder must obtain an entire set of keys, at the right moment, without being noticed, in order to decrypt the entire ciphered message. Encryption is fully automated and all parties, the source user, destination user, and central authority, are clock-free synchronized, and securely authenticated, at all times. The dynamic key encryption system of the present invention is deployable at any level of a system, as there is complete synchronization between parties.
In a second embodiment, the present invention utilizes the continuous authentication mechanism of the first embodiment to implement secure and dynamic authentication between wireless communication network nodes.

Dynamic security authentication for wireless communication networks

New Mexico Technical Research Foundation


An ophthalmology microscopy system for observing fluorescence comprises an imaging system and an illumination system. The imaging system provides at least one optical imaging path producing a magnified multi-dimensional image of an object disposable in a focal plane of the imaging system, and comprises at least one optical observation filter. The illumination system provides an illumination beam path intersecting the focal plane of the imaging system at a variable angle of less than 90°. The microscopy system comprises first and second operating states. In the first operating state, radiation passing through the illumination beam path has at least in a section along the illumination beam path a spectrum free of a pass band of the observation filter. In the second operating state, radiation passing through the illumination beam path has a spectrum having a bandwidth of at least 200 nm in a range from 380 nm to 780 nm.

In ophthalmology, surgical microscopes tailored to the requirements of ophthalmology are frequently used for diagnostic purposes and during surgical interventions. Such surgical microscopes (operating microscopes) are also referred to as ophthalmology surgical microscopes.
Ophthalmology surgical microscopes are optical reflected-light microscopes used during surgical interventions and providing a magnification of typically between 5× and 30×. Surgical microscopes have, as compared to other optical reflected-light microscopes, an objective (objective lens system) with a larger focal length of typically between 175 mm and 550 mm. Characteristic for ophthalmology surgical microscopes is hereby that they often do not directly image an eye's ocular fundus, but indirectly by imaging an intermediate image of the eye which is produced by the eye lens and an ophthalmoscope lens located in the vicinity of the eye. The ophthalmoscope lens is hereby positioned at a distance of 4 mm to 80 mm to the eye's lens. The ophthalmoscope lens may be attached to the ophthalmology surgical microscope in at least one of a pivotable, removable and exchangeable manner. In surgical microscopes, the field of view, i.e. the area in the focal plane from which at least one optical imaging path of the microscope can produce an image at a certain point in time onto the retina of a user of the microscope, is typically larger than 1 mm2. The field of view of a surgical microscope therefore comprises not only one single image point as is the case with scanning microscopes; rather, a multidimensional (especially two or three dimensional) image of the object observed with the surgical microscope is produced at each point in time.
To provide a user with a three dimensional impression of the object to be imaged, which is particularly important with eye surgery, ophthalmology surgical microscopes are often configured as stereo(scopic) microscopes simultaneously providing a pair of optical imaging paths to the eyes of a user. The optical imaging paths of the pair of optical imaging paths intersect near the focal plane of the surgical microscope at a stereoscopic angle of between 3° and 14°.
In ophthalmology surgical microscopes, the image of the object produced with the surgical microscope is provided to a user either by means of an eyepiece (or a pair of eyepieces in stereoscopic surgical microscopes) or is converted into electrical signals using an image converter (or a stereo image converter or a pair of image converters in stereoscopic surgical microscopes), and presented to a user, in addition or alternatively to the eyepieces, on at least one of a monitor and a head-mounted display.
In order to satisfy the ophthalmological requirements, ophthalmology surgical microscopes often comprise an integrated slit lamp and/or a keratoscope.
In ophthalmology it is occasionally necessary to render visible by dyes areas of a patient's eye to be observed. It is for example known to stain the epiretinal (limiting) membrane between the retina and the vitreous body, which itself is colorless and transparent, with indocyanine green, brilliant blue or trypan blue, since these dyes stain the limiting membrane more easily than the adjacent retina and the adjacent vitreous body. The problem is, however, that the respective biocompatibility of the dyes used and in particular that of indocyanine green often allows for only a low dose.
Some of the dyes used in ophthalmology are so called fluorescence dyes which, apart from the general characteristic of dyes of either absorbing or reflecting light of different wavelengths, absorb light of a first wavelength range (the so called excitation band) and convert it into light of a second wavelength range (the so called fluorescence band) different to the first wavelength range. Indocyanine green, for example, absorbs light of a wavelength range from 600 nm to 900 nm, and emits fluorescence in a wavelength range of 750 nm to 950 nm.

Microscopy system for observing fluorescence in ophthalmology


A set of selectable custom water flow restrictors is provided to limit water flow to a predetermined selected gallons-per-minute rate. The restrictor is inserted in-line upstream of the faucet, shower or other water appliance to which water passing through the line is delivered. The restrictor has upstream and downstream chambers connected by a restricting orifice, with the chambers being specially designed to eliminate noise from the restrictor, and to cause the restrictor to be self-cleaning. A downstream water pulse-hammer mitigation disc may be used in conjunction with the main portion of the restrictor in appropriate circumstances.

As the human population increases almost everywhere, the population pressure on the water supply is increasingly felt, especially in arid, desert regions of which Southern California is archetypal. Almost all of the water in Southern California is imported by aqueduct either from Northern California, or from the Colorado River in Arizona.
To appreciate this invention it is important to know that at the time of this writing, several years of severe drought have caused a critical water shortage in Southern California. Many Southern California cities instructed residents not to water their greenery, and to simply let their lawns die. Some cities had water policemen whose specific duty was to patrol the city checking for unauthorized landscape watering. Cities passed out water restricting showerheads to replace older ones, and gave considerable rebates to owners who replaced their conventional toilets with special water saving toilets.
In a nutshell, it became apparent in Southern California that conventional plumbing equipment and techniques could not adequately accomplish the needed water conservation. This problem is also faced in many other areas of the world. Thus, flow restrictors, often built into an appliance such as showerheads, began to be put into service recently. Some flow restrictors, for example those used on faucets, are put right on the dispensing nipple of the faucet, and are easily removed by disgruntled occupants. Most restrictors are subject to becoming clogged, causing their simple removal without replacement in many instances. Any such restrictor or shower head with a built-in flow limitation in its design is subject to becoming clogged with particulates in the water supply, and also, in some cases, to creating a considerable hissing noise in the water lines.
There is a need for a means and method for restricting water flow in a traditional plumbing system which is quiet, self-cleaning and clearing, simple to install, and easily installed out of sight or reach of the water consumer to prevent its arbitrary removal by those who prefer to use water in wasteful quantities. Those who do not pay for the water, such as apartment renters and motel/hotel guests, are notorious for this.


A bar-code reader and a bar-code reading method each of which can perform an accurate, quick reading operation. The bar-code reader scans a bar-code with electromagnetic radioactive rays and then extracts data regarding a bar-width thereof based on the reflected rays; demodulates the bar-width data and creates the demodulated data; judges the presence or absence of a bar-code reproducible combination in the demodulated data and judges the type of combination when the reproducible combination exists; and synthesizes the demodulated data or the character forming the demodulated data according to the type of combination. The bar-code reader and bar-code reading method can be applicable to scanners such as POS systems used in supermarkets, distribution industries, and the like.

1. Field of the Invention
The present invention related to a bar-code reader and bar-code reading method, each of which scans a bar-code with electromagnetic radioactive rays such as a light beam and reads it by utilizing the reflection. More particularly, the present invention relates to a bar-code reader and a bar-code reading method each which is suitable for POS systems (Point of Sales systems) used in supermarkets, distribution industries, and like. The POS systems use scanners acting as bar-code readers. The present invention is directed toward improving the reading performance of a bar-code reader.
2. Description of the Related Art
FIG. 61 is a block diagram showing the configuration of a conventional bar-code reader. Referring to FIG. 61, numeral 101 is a bar-code printed on a surface of an article. The bar-code 101 which is formed of a plurality of black bars and a plurality of white bars arranged alternately represents predetermined data, based on the width of each black bar and the width of each white bar.
Numeral 102 represents an optical system that irradiates a laser beam L2 to the bar-code 101 and receives a reflected light R1, or a laser beam L2 reflected on the bar-code 101. The optical system 102 is formed of a laser emitting unit 103, a scanning mechanism 104, and a photoelectric converter 105.
The laser emitting unit 103 includes a semiconductor laser that emits a laser beam L1 (electromagnetic radioactive rays).
The scanning mechanism 104 which is formed of a polygon mirror rotatable driven with, for example, a motor, reflects the laser beam L1 from the laser emitting unit 103, irradiates the laser beam L1 as a laser beam L2 to the plurality of black bars and the plurality of white bars of the bar-code 101, and then moves and scans at a constant rate in the direction perpendicular to the black and white bars of the bar-code 101.
The scanning mechanism 104 also brings the reflected light R1 moving with scanning of the laser beam L2 as the reflected light R2 to the photoelectric converter 105, by reflecting the reflected light R1 or the laser beam L2 reflected on the bar-code 101.
The photoelectric converter 105 is also formed of a photoelectric converting element such as a photodiode and converts the reflected light (photo input signal) R2 received via the scanning mechanism 104 into an electric signal (with an analog value) according to the light amount and then outputs the converted signal.
Referring to FIG. 61, numeral 106 represents an A.backslash.D converter that digitalized an electrical signal from the photoelectric converter 105 to convert it into a binary signal including a black level signal corresponding to a black bar portion in the bar-code 101 and a white level signal corresponding to a white bar portion in the bar-code 101. The binary signal includes a white level signal with a high level and a black level signal with a low level because the light amount of a reflected light R2 from each white bar portion is usually larger than that of a reflected light R2 from each black bar portion.
Numeral 107 represents a bar-width counter that counts clock signals from a clock generator 108. The bar-width counter 107 produces as clock signal count values the time width of a black level signal portion and the time width of a white level signal portion included in a binary signal from the A.backslash.D converter 106, or a value corresponding to the width of each black bar and a value corresponding to the width of each white bar of an actual bar-code 101.
Numeral 109 represents a memory that stores a bar-width count value from the bar-width counter 107, and 110 represents a CPU. The CPU 110 extracts and demodulates predetermined data of a bar-code 101, based on a bar-width count value (a value corresponding to the width of each black bar or white bar) stored in the memory 109.
In the above-mentioned configuration, the laser beam L1 emitted from the laser emitting unit 103 is irradiated as the laser beam L2 to black bars and white bars of the bar code 101 using said scanning mechanism 104, while it is moved and scanned at a constant rate in the direction perpendicular to the black and white bars of the bar-code 101.
The laser beam L2 sent from the scanning mechanism 104 is scattered and reflected on a surface of the bar-code 101 and it then reenters as the reflected light R1 to the scanning mechanism 104. The reflected light R1 moves with its varying reflection angle following the scanning movement of the laser beam L2. However, the reflected light R1 is reflected by the polygon mirror (a component of the scanning mechanism 104) and it then falls as the reflected light R2 into the photoelectric converting element in the photoelectric converter 105 arranged at a predetermined position.
The photoelectric converter 105 converts the reflected light R2 into an electrical signal according to the amount of light. The A.backslash.D converter 106 digitalized the electrical signal to convert into a binary signal including a black level signal corresponding to each black bar portion and a white level signal corresponding to each white bar portion in the bar-code 101.
Thereafter, the bar-width counter 107 counts clock signals from the clock generator 108. The time widths of black level signal portion and a white level signal portion of a binary signal from the A.backslash.D converter 106 (a value corresponding to the widths of each black bar and white bar of an actual bar-code 101) is measured as the count value of a clock signal. The count value is temporarily stored into the memory 109. The CPU 110 subjects a bar-width count value stored in the memory 109 to a predetermined demodulation process, and then extracts and demodulates predetermined data of the bar-code 101.
As described above regarding FIG. 61, the bar-code 101, as shown in FIG. 62, which is formed of a plurality of black bars 1B and a plurality of white bars 1W arranged alternately represents predetermined data based on the widths of each black bar 1B and each white bar 1W. The black bar 1B or white bar 1W has a width corresponding to a natural integer (e.g. 1 to 4 times: referred to as a module number) of times one module set as a predetermined reference length.
In more detail, the bar-code 101 shown in FIG. 62 has a guard bar GB formed of two black bars 1B corresponding to one module and one white bar 1W corresponding to one module formed between two black bars 1B on the left end and a special center bar SCB formed of three black bars 1B each corresponding to one module and three white bars 1W each corresponding to one module arranged alternately to the black bars on the right end in FIG. 62.
The guard bar GB and the special center bar SCB define both the ends of the bar-code 1. Character portions, for example, 1CHR (character) to 6CHR representing 6 pieces of numerical data (portions showing as the time widths C1 to C6 in FIG. 62, respectively) between the guard bar GB and the special center bar SCB.
Each of the character portions 1CHR to 6CHR is formed of two white bars 1W and two black bars 1B. The number of all the modules is 7. Predetermined numerical data is expressed to each of the character portions 1CHR and 6CHR by combining the number of modules (corresponding to time width T01) included from the left end of the left black bar 1B to the left end of right black bar 1B and the number of modules (Corresponding to time width T02) included from the left end of the left black bar 1B to the left end of the right black bar 1B and the number of modules (corresponding to time width T02) included from the right end of the left black bar 1B to the right end of the right black bar.
The relationship between the combined number of modules and the predetermined numerical data is well known as shown in FIG. 63 and are previously stored and held as a table (matrix). Referring to FIG. 63, letter E represents EVEN or that the sum of modules in the black bars 1B is an even number, and O represents ODD or that the sum of modules in the black bars is an odd number. For example, according to the UPC bar-code structure, the character portion 1CHR shown in FIG. 62 represents "ODD0(00)", the character portion 2CHR represents "ODD1(01)", and the character portion 6CHR represents "ODD2(02)".
Hence, the CPU 110 determines the number modules of each of the time widths (.delta. distance length) T01 and T02 to each of the character portions 1CHR to 6CHR, based on a bar-width count value stored in the memory 109, reads out the numerical data corresponding to combination of two modules from the predetermined table previously stored, and then extracts and demodulates the data of the bar-code 101.
The reading operation of the bar-code 101 in which 6 character portions 1CHR to 6CHR are arranged between the guard bar GB and the special center bar SCB has been explained by referring to FIG. 62. However, as shown in FIG. 64, a conventional bar-code is the bar-code of type which includes the special center bar SCB on the right side of the bar-code 101 shown in FIG. 62 acting as the center bar CB formed of two black bars 1B of one module and two white bars 1W of one module, 6 character portions arranged on both sides with respect to the center bar CB, the left guard bar LGB formed of two black bars 1B of the module number 1 and two white bars 1W of the module number 1 arranged on the left end, and the right guard bar RGB formed of two black bars 1B of the module umber 1 and two white bars 1W of the module number 1 arranged on the right end.
This type of bar-code belongs to the UPC (Universal Product Code) bar-code symbolic standard version. The case where the bar-code 101 of the type shown in FIG. 64 is read will be explained below according to the present invention. The reading operation of the bar-code 101 of the type shown in FIG. 64 is basically performed with the same procedure as that shown in FIG. 62.
In the data extracting and demodulating process for the bar-code 101 shown in FIG. 64, demodulation is normally carried out but he left black unit arranged between the left guard bar LGB and the center bar CB and the right block unit arranged between the right guard bar RGB and the center bar CB of the bar-code 101. The demodulation result is subjected to the general modulo-10 checking. Then if the check result is good, it is judged that one time reading (demodulating process) of the bar-code 101 has been completed.
In this case, the scanning mechanism 104 irradiates 1500 laser beams L2 per second on the bar-code 101. The one-time demodulating process is determined to have completed if any one beam of them crosses the bar-code 101. However, in order to avoid erroneous reading of the bar-code 101, the demodulation data is not judged as valid immediately after a completion of a series of demodulation. The demodulation process is repeated on the same bar-code 101 without completing the reading operation. When data in a black unit to which the modulo-10 checking is good and coincides continuously for a predetermined number of times (coincidence count checking), the reading operation is completed. For example, the method of capturing the demodulation data of a bar-code twice and completing the reading when the previous data agrees with the current data is called "twice coincidence checking".
According to the above-mentioned bar-code checking method, as shown in FIG. 65, the demodulation data becomes valid only when the left block unit arranged between the left guard bar LGB and the center bar CB and the right block unit arranged between the right guard bar RGB and the center bar CB in the bar-code 101 can be scanned with the scanning lines A1 and A2, respectively, or there are the guard bar LGB or RGB and the center bar CB on both ends of demodulation data along the scanning line A1 and the guard bar LGB or RGB and the center bar CB on both ends of demodulations data along the scanning line A2.
Recently, some optical systems irradiate light beams to the bar-code 101 in, for example, 16 scanning directions. In the case of using such an optical system, with a large angle made by the light beam scanning direction and the bar-code 101, as shown in FIG. 65, there is the case where a single scanning line cannot thoroughly can the left block unit arranged between the left guard bar LGB and the center bar CB and the right block unit arranged between the right guard bar RGB and the center bar CB.
For example, as shown in. FIG. 66, when three scanning lines A1 to A3 split-scans three portions of the single bar-code 101, the above-mentioned bar-code reading method cannot obtain demodulation data. However, recently, even when a split scanning is performed as shown in FIG. 66, demodulation is performed with each of the scanning lines A1 to A3 as much as possible. Then data of the signal bar-code 101 is demodulated by combining the resultant plurality of (here, three) pieces of demodulated data in a considerable pattern.
However, where the guard bar or the center bar is included in the demodulated data obtained with each of the scanning lines A1 to A3, and the character of the end is overlapped with the character of the end of another adjacent demodulated data in the demodulated data obtained to each of the scanning lines A1 to A3 (character duplicate checking), the above-mentioned demodulated data becomes valid. In FIG. 66, the shaded portions show character duplicate portions.
The functional structure shown in FIG. 67, for example, has been proposed as a bar-code reader (scanner) for reading the bar-code 101, as shown in FIG. 64. In FIG. 67, numeral 90 represents scanning and extracting means; 91 represents left.backslash.right block unit demodulating means, and 92 represents synthesizing means.
The scanning and extracting means 90 scans a bar-code with light rays (electromagnetic radioactive rays) and extracts bar-width data from the reflected light (corresponding to the portion of constituted of elements 102 to 108 in FIG. 61).
The left.backslash.right unit demodulating means 91 implements a demodulating process every left block unit or right block unit arranged between the guard bar and the center bar of a bar-code, based on the bar-width data extracted by the scanning and extracting means 90, and then obtains demodulated data. The synthesizing means 92 synthesizes demodulated data demodulated every left or right block unit. The left.backslash.right block unit demodulating means 91 and the synthesizing means 92 are arranged as the function of the CPU 110 in, for example, in FIG. 61.
In the device having the functional structure shown in FIG. 67. where there are demodulated data in left block unit and the demodulated data in right block unit each demodulated by the left.backslash.right block unit demodulating means 91, one including only a guard bar and the other including a guard bar and a center bar, the demodulated data in the left block data unit has a character duplicated at the most remote end and the demodulated data in the right block data unit has a character duplicated at the most remote end. If the demodulated data passes the modulo-10 checking, the synthesizing means 92 synthesizes demodulation data (bar-width data) in the left block unit and demodulation data (bar-width data) in the right block unit.
For example, as shown in FIG. 68(a), where the characters A, B, C, and D are obtained by scanning with the beam .alpha. from the scanning and extracting means 90 and demodulating with the left.backslash.right block unit demodulating means 91, and the characters D, E, F, a, b, c, d, e, and f are obtained by scanning with the beam B from the scanning and extracting means 90 and demodulating with the left.backslash.right block unit demodulating means 91, the character "D" is overlapped or duplicated. Hence when demodulation data along two beam scanning lines .alpha. and .beta. clears the modulo-10 checking, the synthesizing means 92 can synthesize the characters A to F and a to f so the bar-code reading can be preformed.
Recently, bar-codes have been used extensively as represented by the POS systems used in distribution industries. However, bar-codes with low print quality are increasing. There is great possibility that the bar-code with low print quality may be erroneously read. The possibility that paper surface noises or characters are erroneously read as bar-code data is considerably strong.
Therefore it has been desirable that even bar-codes with low print quality can be read with high accuracy without being erroneously read. The bar-code erroneous reading may be caused by curvature of bar-code, wrinkles, and flaws on the reading glass window surface of the bar-code reader.
Paper surface noises or characters may be erroneously read and demodulated as characters of a bar-code after light beams sweep across the guard bar, center bar, and normal character. In this case, since the character duplicate checking is not approved, the demodulation result becomes invalid.
In the bar-code reader shown in FIG. 67, in the reading operation of the bar-code divided in two portions, if the guard bar and the center bar are detected on each scanning line, bar-code data is sampled as much as possible that they can be demodulated along each scanning line. When a combination of the demodulation data in the left block unit and the demodulation data in the right block unit to which an overlap (duplicate portion) can be considered in the bar-code passes the modulo-10 checking, the bar-width data is synthesized.
However, when the scanning and extracting means 90 scans the bar-code, paper surface noises or characters may be erroneously read as a bar-code or a bar-code is erroneously read due to curvature of paper surface or a fold in the paper.
For example. FIG. 68(b) shows the case where the characters A, B, C, D, and E' can be demodulated along the scanning line of the beam .alpha., and the case where characters D, E, F, a, b, c, d, e, and f can be demodulated along the scanning line of the beam .beta.. The character "E'" obtained by the beam .alpha. is dummy demodulation data obtained by erroneously demodulating the original character "E" which cannot be completely scanned due to paper surface noises or characters. In this case, the character "D" exists in common in the demodulation data in the left unit and the demodulation data in the right unit. However, the character "E" differs from the character "E'". Since the character at the most remote end of the demodulation data in the right block unit does not agree with the character at the most remote end of the demodulation data in the left block unit, the bar-width data cannot be synthesized. For that reason, the same process must be made again by discarding data of the characters A to E' and D to f already obtained by demodulation. Hence, the bar-code reader may have a poor efficiency, consumes a long processing time, continues to erroneously demodulate and read characters.
In order to avoid an erroneous reading, as described above, where the same data is demodulated continuously a predetermined fixed number of times, a process of validating the demodulation result is performed. However, in the coincidence count checking, the reference number of times being always constant may cause an erroneous reading in some bar-code reading states. It is considered to set the reference number of times to a large value from the beginning. In such a case, even when one-time scanning and demodulating process allows error-free reading, the demodulation result in not validated till the same data is demodulated by the reference number of times. Hence there is a disadvantage in that the bar-code reading process takes much time.

Bar-code reader and bar-code reading method for detecting various possible reproducible bar code combinations and synthesizing information therefrom


A blower includes a fan that causes momentum to air by rotation, a shaft that defines a rotation axis of the fan, a bearing that supports the shaft outside of the fan, and a weight that is movable in a direction of rotation of the fan. In the fan, the weight is located opposite to the bearing with respect to an end of the fan adjacent to the bearing, and thus an increase in weight by the weight can be reduced.

In a conventional blower, a balance adjustment was performed by adding a balance weight to a fan (plus balance adjustment) or removing a surplus weight (minus balance adjustment) for cancelling vibrations between the fan and a motor as a rotating body. For example, patent document 1 discloses a centrifugal blower in which the minus balance adjustment is performed.
Patent document 2 discloses an electric blower in which the balance adjustment is automatically performed by arranging a weight to be movable between a fan and a washer that fixes the fan. According to the conventional art of the patent document 2, there is a merit that the time and effort of the balance adjustment in a manufacturing process decrease. However, because the weight of the rotating body increases due to the weight, there is a possibility that an efficiency of the blower deteriorate.


This invention relates to electrophoretic displays having improved performance. The threshold promoter of the present invention may induce or significantly enhance the threshold effect by improving the particle-particle interaction and/or the particle-electrode interaction. The promoter may be present in the system as a soluble or micelle molecule in the electrophoretic fluid or an adsorbed or chemically bonded molecule on the surface of particles. The use of such a threshold promoter does not show a detrimental effect on the display switching rate.

1. Field of the Invention
This invention relates to electrophoretic displays having improved performance.
2. Brief Description of Related Art
The electrophoretic display (EPD) is a non-emissive device based on the electrophoresis phenomenon of charged pigment particles suspended in a dielectric solvent. It was first proposed in 1969. The display usually comprises two plates with electrodes placed opposing each other and separated by spacers. One of the electrodes is usually transparent. A suspension composed of a colored solvent and charged pigment particles is enclosed between the two plates. When a voltage difference is imposed between the two electrodes, the pigment particles migrate to one side and then either the color of the pigment or the color of the solvent can be seen according to the polarity of the voltage difference.
There are several different types of EPDs. In the partition type EPD (see M. A. Hopper and V. Novotny, IEEE Trans. Electr. Dev., 26(8):1148-1152 (1979)), there are partitions between the two electrodes for dividing the space into smaller cells in order to prevent undesired movement of particles such as sedimentation. The microcapsule type EPD (as described in U.S. Pat. Nos. 5,961,804 and 5,930,026) has a substantially two dimensional arrangement of microcapsules each having therein an electrophoretic composition of a dielectric solvent and a suspension of charged pigment particles that visually contrast with the dielectric solvent. Another type of EPD (see U.S. Pat. No. 3,612,758) has electrophoretic cells that are formed from parallel line reservoirs. The channel-like electrophoretic cells are covered with, and in electrical contact with, transparent conductors. A layer of transparent glass from which side the panel is viewed overlies the transparent conductors.
An improved EPD technology was disclosed in co-pending applications, U.S. Ser. No. 09/518,488 filed on Mar. 3, 2000 (corresponding to WO01/67170), U.S. Ser. No. 09/606,654 filed on Jun. 28, 2000 (corresponding to WO02/01280) and U.S. Ser. No. 09/784,972 filed on Feb. 15, 2001 (corresponding to WO02/65215). The improved EPD comprises closed cells formed from microcups of well-defined shape, size and aspect ratio and filled with charged pigment particles dispersed in a dielectric solvent.
As in liquid crystal and other displays, an EPD may be a segment display, a passive matrix display or an active matrix display, depending on the driving mechanism and the circuitry design. The passive matrix driving system is one of the most cost effective driving mechanisms. The system has row electrodes on the top side and column electrodes on the bottom side, of the cells. In most cases, the top row electrodes and the bottom column electrodes are perpendicular to each other. Generally speaking, a threshold voltage of no less than ⅓ of the driving voltage is required to suppress or eliminate the undesirable cross-bias or crosstalk effect in adjacent pixels of a passive matrix display.
Crosstalk occurs when the particles in a cell are biased by the electric field of a neighboring cell. FIG. 1 provides an example to illustrate crosstalk. A and B are two cells of a passive matrix EPD with a voltage bias of 30V and 0V, respectively. The bias voltage of the cell A drives the positively charged particles towards the bottom of the cell. Since cell B has no voltage bias, the positively charged particles in cell B are expected to remain at the top of the cell. However, if the two cells, A and B, are close to each other, the top electrode voltage of cell B (+30V) and the bottom electrode voltage of cell A (0V) create a crosstalk electric field which may force some of the particles in cell B to move downwards. Widening the distance between adjacent cells may eliminate such a problem; but the distance may also reduce the resolution of the display.
Alternatively, the crosstalk problem can be lessened if a cell has a significantly high threshold voltage. A large gamma (or a steep slope) of the response-voltage characteristic curve is also desirable to increase the resolution of a passive matrix device. However, cells in EPDs made using the electrophoretic materials and techniques currently available typically do not have the required response-voltage characteristics to prevent the undesirable movement of particles. As a result, the EPDs constructed from these materials and techniques usually cannot achieve high resolution.
Cross bias is another well-known problem associated with a passive matrix display. The voltage applied to a column electrode not only provides the driving bias for the cells in the scanning row, but it also affects the bias across the non-scanning cells in the same column. This undesired bias may force the particles of non-scanning cells to migrate to the opposite electrode. This undesirable particle migration causes visible optical density change and reduces the contrast ratio of the display.
In addition, in order to scan through all rows of electrodes in a frame within a reasonable time scale, a fast response rate is also highly desirable. However, most of the EPDs currently available have not shown an acceptable threshold characteristics or response rate required.
Electrophoretic fluids having inherent threshold characteristics have been reported by, for example, I. Ota, et al, in SID Proceedings, 18, 243 (1977) and Evans, et al, in U.S. Pat. No. 3,612,758. The fluids have reportedly shown disadvantages in response time, operation voltage, brightness, image uniformity or display longevity. In most cases, the fluid is in direct contact with the electrode conductor. The direct contact may enhance the particle-electrode interaction and, in some cases, result in a threshold, but with trade-offs in image uniformity and display longevity probably due to the irreversible adsorption and/or redox reaction(s) at the electrode surface.
A system having gating electrodes was disclosed in U.S. Pat. Nos. 4,655,897 and 5,177,476 (assigned to CopyTele, Inc.) to provide EPDs capable of high resolution at a relative high driving voltage using a two layer electrode structure, one of which layers serves as a gating electrode. Although these documents teach how the threshold voltage may be raised by the use of gating electrodes, the cost for fabricating the two electrode layers is extremely high due to the complexity of the structure and the low yield rate. In addition, in this type of EPDs, the electrodes are exposed to the solvent, which could result in an undesired electroplating effect. Electrophoretic displays comprising an in-plane gating electrode or a holding electrode to reduce or eliminate the cross bias and crosstalk of a passive matrix EPD have also been disclosed in copending patent applications, U.S. Ser. No. 10/242,335 filed on Sep. 11, 2002 (WO03/23510) and U.S. Ser. No. 10/282,444 filed on Oct. 28, 2002 (WO03/38512), respectively. However, the cost associated with the additional electrode is still an issue. Alternatively, magnetic particles and a magnetic electrode have been disclosed in U.S. Pat. No. 6,239,896 (assigned to Canon) to provide the required threshold, but also at the expense of manufacturing cost.
Therefore, there is a need for a cost effective method for inducing or enhancing the threshold voltage with a sharp gamma and high switching rate, without the trade-offs in image uniformity and display longevity, and without the need of complex circuitry designs.
The whole content of each document referred to in this application is incorporated by reference into this application in its entirety.


Various systems, methods, and programs embodied in a computer readable medium are provided for determining a worst-case impedance and worst-case voltage of a power supply loop coupled to a power input of a die. In various embodiments, the worst-case impedance of a power supply loop is determined and a reference voltage at the power input of the die associated with an average current generated at a power supply included in the power supply loop. A maximum change in a current at the power input of the die is also measured and an estimate of a worst-case voltage at the power input of the die is calculated based upon the worst-case impedance, the reference voltage, and the maximum change in the current.

Development of microprocessor technology has seen decreasing power supply voltages that are more susceptible to interference by noise, decreasing signal transition times, decreasing die sizes, increasing power supply currents, and increasing clock speeds. As a result, ever more significant demands are placed upon the power supplies of microprocessor circuits. Such demands typically result in significant voltage and current variation between power and ground conductors.
Knowledge as to the nature of the extreme voltages that occur between a microprocessor power and ground due to the operation of a microprocessor or other type of circuit is useful for estimating power distribution performance and for predicting signal integrity in a microprocessor. However, current approaches are inadequate to determine such extreme voltages.

Determination of worst case voltage in a power supply loop

Hewlett-Packard Development Company, L.P.


A wearable blood pressure measuring device includes a wristband, a valve plate, a gas-collecting seat, a gas transportation device, an elastic medium and a pressure sensor. The wristband has a mounting zone. The mounting zone has a first accommodation recess, a second accommodation recess, a gas-collecting hole and a pressure-releasing hole. The first accommodation recess and the second accommodation recess are in fluid communication with each other through the gas-collecting hole. When the gas transportation device is enabled to transport the gas to the elastic medium, the elastic medium is inflated with the gas and expanded to push the pressure sensor to be in close contact with a measurement part of a user's body, thereby measuring a blood pressure value of a target artery through a scanning operation.

Nowadays, the pace of life becomes fast and the personal pressure is growing. As the awareness of the pursuit of personal health is gradually evolving, people want to regularly monitor or examine their health condition. Conventionally, the human physiological health information is measured through a fixed sphygmomanometer or a large-scale detection instrument. The detection instrument usually includes a motor-driven gas pump, an air bag, a sensor, a gas-releasing valve, a battery, and so on. During the operation of the motor-driven gas pump, the motor-driven gas pump is readily suffered from frictional loss. After these components are assembled, the volume of the product is large and thus the product is not suitable for frequent use. If a small-sized motor-driven gas pump is used, the frictional loss is increased and more energy is consumed.
For facilitating the ordinary persons to regularly monitor their own health conditions and allowing the monitoring device to be easily carried, many wearable health monitoring devices are introduced into the market. Generally, the wearable health monitoring devices are used for measuring the health conditions according to the optical detection technologies. Since the precision of the optical detection is not high enough, the detected value is possibly erroneous so that reliable data cannot be obtained effectively. Since the users fail to acquire accurate data relative to their health condition, the users may misjudge their health condition.
Generally, for measuring the physiological information of a user, a specified part of the user's body (e.g., head, heart, wrist or ankle) is monitored by a measuring device. At the specified part, the pulse blood pressure and heartbeat in the human body are sensed the most easily. By sensing the specified part, the physiological health information can be rapidly and effectively realized. As mentioned above, the precision of the wearable health monitoring device operated according to the optical detection technology is not high and the measured data is usually not reliable. Moreover, the commercially-available sphygmomanometers or other measuring instruments with higher reliability have bulky volume and fail to meet the requirements of small size, light weightiness and easy portability.
Therefore, there is a need of providing a wearable blood pressure measuring device in order to address the above-mentioned issues. The wearable blood pressure measuring device is small-sized, miniaturized, portable, power-saving and high-precise.

Wearable blood pressure measuring device


A process for the low pressure chemical vapor deposition of silicon nitride from ammonia and a silane of the formula: (t-C.sub.4 H.sub.9 NH).sub.2 SiH.sub.2 provides improved properties of the resulting film for use in the semiconductor industry.

The present invention is directed to the field of low pressure chemical vapor deposition of silicon nitride films using bis(tertiarybutylamino)silane, a novel organosilicon source material for silicon nitride.
In the fabrication of semiconductor devices, a thin passive layer of a chemically inert dielectric material such as, silicon nitride (Si.sub.3 N.sub.4) is essential. Thin layers of silicon nitride function as diffusion masks, oxidation barriers, trench isolation, intermetallic dielectric material with high dielectric breakdown voltages and passivation layers. Many other applications of silicon nitride coatings in the fabrication of semiconductor devices are reported elsewhere, see Semiconductor and Process technology handbook, edited by Gary E. McGuire, Noyes Publication, New Jersey, (1988), pp 289-301; and Silicon Processing for the VLSI ERA, Wolf, Stanley, and Talbert, Richard N., Lattice Press, Sunset Beach, Calif. (1990), pp 20-22, 327-330.
The present semiconductor industry standard silicon nitride growth method is by low pressure chemical vapor deposition in a hot wall reactor at >750.degree. C. using dichlorosilane and ammonia.
Deposition of silicon nitride over large numbers of silicon wafers has been accomplished using many precursors. The low pressure chemical vapor deposition (LPCVD) using dichlorosilane and ammonia requires deposition temperatures greater than 750.degree. C. to obtain reasonable growth rates and uniformities. Higher deposition temperatures are typically employed to get the best film properties. There are several drawbacks in these processes and some of these are as follows:
i) Deposition under 850.degree. C. gives poor hazy films with chlorine and particle contamination; PA1 ii) Silane and dichlorosilane are pyrophoric, toxic compressed gases; PA1 iii) Films formed from dichlorosilane result in the formation of less uniform films; and PA1 iv) Films from dichlorosilane have contaminants, such as chlorine and ammonium chloride, which are formed as byproducts. PA1 1) They contain N-methyl groups, the methyl groups tend to migrate to the silicon surface readily and contaminate the films with carbon during a CVD process. In order to reduce the amount of carbon, the process involves high temperatures (>700) and high ammonia ratios (>10:1). With increased ammonia ratios the deposition rates dramatically reduce due to reactant depletion. PA1 2) They do not contain NH bonding and they do not involve secondary silanes. PA1 3) At lower temperatures the deposition rates and uniformities are very poor (>5%). PA1 a) heating a substrate to a temperature in the range of approximately 500.degree.-800.degree. C. in said zone; PA1 b) maintaining the substrate in a vacuum at a pressure in the range of approximately 20 mTorr-2 Torr in said zone; PA1 c) introducing into said zone ammonia and a silane of the formula: (t-C.sub.4 H.sub.9 NH).sub.2 SiH.sub.2 ; and PA1 d) maintaining the conditions of a) through c) sufficient to cause a film of silicon nitride to deposit on the substrate.
Japanese Patent 6-132284 describes deposition of silicon nitride using organosilanes with a general formula (R.sub.1 R.sub.2 N).sub.n SiH.sub.4-n (where R.sub.1 and R.sub.2 range from H--, CH.sub.3 --, C.sub.2 H.sub.5 --C.sub.3 H.sub.7 --, C.sub.4 H.sub.9 --) by a plasma enhanced chemical vapor deposition and thermal chemical vapor deposition in the presence of ammonia or nitrogen. The precursors described here are tertiary amines and do not contain NH bonding as in the case of the present invention. The deposition experiments were carried out in a single wafer reactor at 400.degree. C. at high pressures of 80-100 Torr. The Si:N ratios in these films were 0.9 (Si:N ratios in Si.sub.3 N.sub.4 films is 0.75) with hydrogen content in the deposited films. The butyl radical is in the form of isobutyl.
Sorita et al., J. Electro. Chem. Soc., Vol 141, No 12, (1994), pp 3505-3511, describe deposition of silicon nitride using dichlorosilane and ammonia using a LPCVD process. The major products in this process are aminochlorosilane, silicon nitride and ammonium chloride. Formation of ammonium chloride is a major drawback of using Si--Cl containing precursors. The formation of ammonium chloride leads to particle formation and deposition of ammonium chloride at the backend of the tube and in the plumbing lines and the pumping system. Processes which contain chlorine in the precursors result in NH.sub.4 Cl formation. These processes require frequent cleaning and result in large down time of the reactors.
B. A. Scott, J. M. Martnez-Duart, D. B. Beach, T. N. Nguyen, R. D. Estes and R. G. Schad., Chemtronics, 1989, Vol 4, pp 230-234., report deposition of silicon nitride using silane and ammonia by LPCVD in the temperature region of 250.degree.-400.degree. C. Silane is a pyrophoric gas and is difficult to control for the deposition of clean silicon nitride due to partial gas phase reaction.
J. M. Grow, R. A. Levy, X. Fan and M. Bhaskaran, Materials Letters, 23, (1995), pp 187-193, describe deposition of silicon nitride using ditertiarybutylsilane and ammonia by LPCVD process in the temperature range of 600.degree.-700.degree. C. The deposited silicon nitride films were contaminated with carbon impurities (10 atomic %). This is mainly due to the presence of direct Si--C bonds in the precursor.
A. K. Hochberg and D. L. O'Meara, Mat. Res. Soc. Symp. Proc,. Vol. 204, (1991), pp 509-514, report deposition of silicon nitride and silicon oxynitride by using diethylsilane with ammonia and nitric oxide by LPCVD. The deposition was carried out in the temperature range of 650.degree. C. to 700.degree. C. The deposition is limited to deposition at 650.degree. C. and the deposition rate drops to below 4 .ANG./min at lower temperatures. In the LPCVD process, precursors which contain direct Si--C carbon bonds result in carbon contamination in the films. Carbon free deposition requires greater than 5:1 NH.sub.3 to precursor ratios. At lower ammonia concentrations, the films were found to contain carbon. Diethylsilane+ammonia processes typically require covered boats or temperature ramping to improve uniformities across the wafers.
U.S. Pat. No. 5,234,869 and R. G. Gordon and D. M. Hoffman, Chem. Mater., Vol. 2, (1990), pp 482-484 disclose other attempts to reduce the amount of carbon involved aminosilanes, such as tetrakis(dimethylamino)silane. The temperature of deposition is in the range of 300.degree.-1000.degree. C. with pressures in the range of 1 mTorr-10 Torr. The presence of direct Si--N bonds and the absence of Si--C bonds were expected to give lower carbon concentrations in the films. However, there are three main disadvantages with precursors of this class.
The prior art has attempted to produce silicon nitride films at low temperatures, at high deposition rates and low hydrogen and carbon contamination. However, the prior art has not been successful in achieving all these goals simultaneously with one silicon precursor. The present invention has overcome the problems of the prior art with the use of a precursor unique to the formation of silicon nitride which avoids the problems of plasma deposition, operates at low thermal conditions, avoids Si--C bonds to reduce carbon contamination of the resulting films, has low hydrogen contamination, as well as avoiding chlorine contamination and operates at low pressures (20 mTorr-2 Torr) in a manufacturable batch furnace (100 wafers or more), as will be described in greater detail below.

Silicon nitride from bis(tertiarybutylamino)silane


A safety apparatus safety apparatus for use with a sheave has a first plate suitable for placement over one side of the sheave, a second plate suitable for placement on an opposite side of the sheave, and a carriage positioned at a periphery of the first and second plates. The carriage extends across a gap between the plates. The carriage is movable along the peripheries of the first and second plates. The carnage includes a first carriage and a second carriage which are independently movable with respect to each other. The carriage includes a first body, a second body, and a discoidal member pivotally mounted to the first and second bodies. The discoidal member has a hole suitable for allowing the cable of the sheave to pass freely therethrough.

1. Field of the Invention
The present invention relates to safety apparatus for use with sheaves and pulleys. More particularly, the present invention relates to a safety apparatus that prevents fingers from entering into an area adjacent to the sheave or pulley. Additionally, the present invention relates to a safety apparatus that can be mounted to the sheave or pulley and which is adaptable to the various orientations of the cable extending from the sheave or pulley.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
Pulleys and sheaves are used in a wide variety of offshore operations. In certain circumstances, the sheaves or pulleys can be supported from an overhead position so as to facilitate the ability to lift an object from a location so as to move the object to another location. In other circumstances, the pulleys or sheaves may extend in a horizontal orientation adjacent to a floor. In this configuration, the pulleys and/or sheaves can be utilized so as to adjustably position an object on the floor. During the use of such pulleys and sheaves, the operators will typically manipulate a line by pulling oil the line. The use of the pulleys and sheaves facilitates the ability, by way of mechanical advantage, to direct an object to another location. Typically, operators will wear gloves while manipulating the line that extends over the pulley.
In some or certain circumstances, the worker associated with such pulleys may move their hands very close to the actual pulley. If the gloved hand should move too close to the pulley, there is a possibility of the glove being caught in the area between the line and the pulley. This can draw the worker's hand into the pulley. Under such circumstances, finger severing or impalement can occur. As such, a need has developed so as to pro vide a safety apparatus that effectively prevents the worker from ever encountering the situation where his or her fingers are drawn into the pulley.
As used herein, the term "sheave" can refer to a block, a pulley, or combinations thereof. The term "pulley" and "sheave" are used interchangeably herein. Additionally, the term "line" can refer to ropes, wire ropes, cords, cables and belts.
It is important to note that the operation of sheaves and pulleys can cause the line to extend at various angles. Under certain circumstances, there will be a relatively wide angle between the portions of the line that extend between the worker and the object to be manipulated. In other circumstances, the line will extend generally adjacent to the object to be manipulated. As such, any safety apparatus would have to be adaptable to the various orientations of line that are required in the particular applications.
In the past, various patents have issued relating to safety and protection devices for use with sheaves and pulleys.
For example, U.S. Pat. No. 968,304, issued on Aug. 23, 1910 to G. H. Winslow, describes a pulley guard. This pulley guard includes a shield in the form of a disc or plate having an upper portion provided with a slot terminating in an enlarged aperture to receive and lock over a headed stud or support. The disc or plate has a lower portion that covers the rotary member and is provided with a slot to slidingly engage the shaft of the rotary member. There is an aperture above the slot to afford access to the rotary member. A means is provided for adjusting and locking the plate in different positions on the support.
U.S. Pat. No. 1,175,065, issued on Mar. 14, 1916 to H. Kotten, provides a shaft and pulley guard. In particular, there is shaft guard, a means for vertically adjusting and supporting the shaft guard, a pulley guard formed in sections and having an interlocking engagement with one portion of the shaft guard, and a means for supporting and relatively adjusting the pulley guard sections transversely.
U.S. Pat. No. 1,820,322, issued on Aug. 25, 1931 to B. L. Polkosnik, teaches a pulley guard and banger. This pulley guard and hanger is stamped from a single piece of sheet metal so as to present a central bar member having extensions reaching in opposite directions at right angles from its ends. The bar is bent to produce an open loop extending outwardly. The extensions are looped to encompass the sides of the pulley. The free ends of the side loops are overlapped and secured to the junction of the connected ends.
U.S. Pat. No. 4,114,473, Sep. 19, 1978 to H. M. Pollak, describes guard for belt pulley. The guard includes a top wall for overlying a portion of the pulley's side face between the nips of the belt and the pulley. A side wall is connected to the top wall and extending generally at right angles therefrom. The guard has three projections on the side wall with each projection terminating in an arcuate end face juxtaposed to the inner diameter of one of the grooves of the pulley. Each arcuate end face on the projections has a center of curvature corresponding to the axis of rotation of the pulley. A mounting means is connected to one of the walls for mounting the walls in a position so that each of the projections enters one of the pulley grooves and one projection occupies substantially all the pulley grooves that are unoccupied by the belt.
U.S. Pat. No. 4,139,064, issued on Feb. 13, 1979 to D. R. Dobberpuhl, provides a belt guard for a rotary tiller. The guard encloses the belt and has its forward end pivotally supported on a bracket fixed to the engine by a fastener which also serves to retain a belt guide in place. The rear end of the belt guard is supported for swinging about the forward connection.
U.S. Pat. No. 4,648,855, issued on Mar. 10, 1987 to Palloch et al., discloses a belt guard for industrial sewing machines which includes a cover made of two cover halves that can be clasped together. The cover extensively covers a V-belt pulley part.
U.S. Pat. No. 4,917,656, issued on Apr. 17, 1990 to Sato et al., provides a rear belt guard for use in a sewing machine. The guard member is fixed to the table for covering a rear portion of a belt of the belt device that is exposed on the table. The guard member has an inclined wall upper portion provided with a notched recess for receiving the belt when the head is turned rearwardly. A cover member is openable and slidable over the notched recess. The cover member is urged by a spring in as direction to be closed.
U.S. Pat. No. 5,180,343, issued on Jan. 19, 1993 to M. A. Reed, discloses a pulley guard apparatus that can be mounted to an interior surface of projecting flanges mounted on the pulley structure. Arcuate discs are arranged in confrontation in an edge-to-edge relationship with outer edges of the first and second pulley flanges preventing the binding and abrasion of a pulley belt.
U.S. Pat. No. 5,461,848, issued on Oct. 31, 1995 to L. Anthony, provides as mower pulley guard for covering a wheel pulley. A semi-circular panel is positionable over the wheel pulley of the mower. A pair of lateral panels extend from opposed ends of the semi-circular panel and cooperate with a pair of mounting projections to secure the semi-circular panel to a pulley housing of the mower. The device cooperates with a cover plate of the mower to fully enclose the wheel pulley to preclude an entrance of debris into the pulley housing.
U.S. Pat. No. 5,957,796, issued on Sep. 28, 1999 to V. McLean, provides a belt guard having a main rear wall with two slots for engaging over a pair of shafts of the pump jack at the drive belt on the pulleys on the drive shafts. The rear cover portion includes a peripheral wall extending around the sides and top of the peripheral edge with the bottom of the cover panel being opened. A front panel portion fits over the rear cover panel with a lip engaging onto the peripheral wall to which it is secured.
U.S. Design Patent No. D540,256, issued on Apr. 10, 2007 to J. R. Bullock., Jr describes a belt guard which includes a first housing that is hingedly connected to a second housing. Hinge pins can be utilized so as to fix the housings into a closed position.
U.S. patent application Ser. No. 13/650,393 is very effective in promoting the hand safety of users of such sheaves. This application describes a safety apparatus that has a sheave with a surface extending circumferentially therearound, a first housing interconnected to the sheave, a second housing interconnected to the sheave and pivotally mounted to the first housing, and a line extending over the surface of the sheave and through the interior of each of the first and second housings. Each of the first and second housings has a hole formed at an end thereof opposite the sheave. The line has a first portion extending through the hole of the first housing and a second portion extending through the hole of the second housing. Bushings are respectively received within the holes of the housings.
With this prior hand safety protection apparatus, it was found that there were certain difficulties. Importantly, in order to install this hand safety protection apparatus, it was necessary to remove the center shaft of the sheave This created certain difficulties in installation. Additionally, it was necessary to thread the cable through each of the bushings so as to allow for the proper installation of the hand safety protection apparatus. Additionally, the manufacturing of the hand safety protection apparatus of this application was somewhat difficult.
It is an object of the present invention to provide a safety device for sheaves and pulleys that effectively prevents impaling or severing of fingers.
It is another object of the present invention to provide a safety device for use with sheaves and pulleys which does not interfere with the standard operation of the pulley, sheave or block.
It is another object of the present invention to provide as safety apparatus for use with sheaves and pulleys which is adaptable to various angles and orientations of the line with respect to the pulley.
It is another object of the present invention provide a safety apparatus which avoids the removal of the center shaft of the sheave.
It is another object of the present invention to provide a safety apparatus that is adaptable over the existing sheave head and nut.
It is another object of the present invention to provide a safety apparatus that avoids any interference with mid-line attachment.
It is another object of the present invention provide a safety apparatus which avoids the need for offset legs.
It is a further object of the present invention to provide as safety apparatus in which the construction utilizes identical components.
It is a further object of the present invention provide as safety apparatus in which the design is easily scalable to the various configurations of sheaves.
It is a further object of the present invention to provide a safety apparatus that is extremely light.
It is another object of the present invention to provide a safety apparatus that allows for cosign compensation of the centerline of the cable relative to the sheave yoke track.
It is still a further object of the present invention to provide a safety apparatus that is easy-to-use, easy to manufacture, easy to install and relatively inexpensive.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.


Two first semiconductor layers are on a silicon substrate at a given distance from each other. Two second semiconductor layers are on the respective first semiconductor layers and includes a material different from a material of the first semiconductor layers. A first channel region is formed like a wire between the two second semiconductor layers. A first insulating layer is around the first channel region. A second insulating film is on each of opposite side surfaces of the two first semiconductor layers. A third insulating film is on each of opposite side surfaces of the two second semiconductor layers. A gate electrode is on the first, second, and third insulating films. Film thickness of the second insulating film is larger than film thickness of the first insulating film.

1. Field of the Invention
The present invention relates to a semiconductor device, and in particular, to a semiconductor device in which a gate electrode is located so as to surround the entire circumference of a channel region, and a method for manufacturing the semiconductor device.
2. Description of the Related Art
In recent years, with the improved functions and integration of semiconductor integrated circuits, MOS transistors have been increasingly miniaturized. However, conventional MOS transistors have a small current on/off ratio. Thus, in order to provide a desired on current, the MOS transistor needs to be configured such that a gate electrode has an increased width or a plurality of gate electrodes are formed on the same plane. The increase in width and the formation of a plurality of gate electrodes on the same plane increase the area occupied by field effect transistors, disadvantageously hindering an increase in circuit density.
Thus, as a structure for obtaining the desired on current, for example, a gate-all-around (GAA) transistor has been proposed (see, for example, Jpn. Pat. Appln. KOKAI Application No. 2005-229107).
In the GAA transistor, the gate electrode is formed so as to wrap around a channel region. Thus, when a voltage is applied to the gate electrode, electric fields are likely to concentrate in the channel region. Thus, the on/off ratio of a switching current can be set to a large value. Furthermore, a large number of channels can be formed on the same plane, enabling an increase in on current.
However, in the conventional GAA transistor, a parasitic capacitance is produced on the side surfaces (the end surfaces of the gate in the longitudinal direction) and bottom surface of the gate electrode. In particular, a large parasitic capacitance is produced on the side surfaces of the gate electrode. In operation, this disadvantageously slows the speed at which the voltage of the gate electrode is increased or reduced in response to an applied voltage.

Semiconductor device comprising gate electrode surrounding entire circumference of channel region and method for manufacturing the same


A method and system are provided that allows a wireless terminal to share an allocated frequency spectrum for communications over two different networks while mitigating cross interference. For wireless terminals equipped with a single antenna, interference mitigation may be achieved by allocating first communication channels to a first network and allocating second communication channels to a second network, wherein the second communication channels are allocated within one or more of the first communication channels. For wireless terminals having multiple antennas, interference mitigation may be achieved with two orthogonally polarized antennas, where each antenna is used for communications with a different network. Consequently, a wireless terminal having a channel allocation for communicating over the first wireless network may reuse the same channel allocation to establish a communication link with a second wireless terminal via a second wireless network using at least part of the channel allocation for the first wireless network.

1. Field
Various embodiments are directed to methods and apparatus for wireless communication and, more particularly, to methods and apparatus related to interference management between a wide area network (WAN) and peer-to-peer (P2P) network using polarization antennas.
2. Background
In a wireless network, e.g., an ad hoc network, in which a network infrastructure does not exist, a terminal has to combat certain challenges in order to set up a communication link with another peer terminal. One challenge is that when a terminal just powers up or moves into a new area, the terminal may have to first find out whether another terminal is present in the vicinity before any communication between the two terminals can start.
The general solution to the above problem of identification and acquisition is to let the terminal transmit and/or receive signals according to certain protocol. Note that the protocol and the signal have to be designed carefully so that the solution is robust and power efficient. Robustness is essential. For example, the terminals often may not have a common timing reference, e.g., because of the lack of the network infrastructure. So it is possible that when a first terminal is transmitting a signal and a second terminal is not in the receiving mode, the transmitted signal does not help the second terminal to detect the presence of the first terminal. Power efficiency has great impact on the battery life of the terminals and is thus another important issue in the wireless system.
Consequently, a problem exists in how to implement such ad hoc network while extending the battery life of the terminals.

Method and apparatus for interference management between networks sharing a frequency spectrum


The present invention provides an accelerating structure capable of increasing a degree of vacuum at a middle part inside the accelerating structure while confining an alternating electric field to the inside. An accelerating structure 1 is formed of a plurality of annular discs 2 and 3 serially connected into a cylindrical shape. At least one of the discs 3 disposed at a middle part of the accelerating structure 1 includes: a choke structure formed by a choke filter 7; and a vacuum port 8 opened in an outer circumferential surface of the disc on an outer circumferential side radially outward from the choke structure, and the vacuum port 8 is connected to an external exhaust device.

An accelerator is essentially equipped with: an accelerating structure which internally accelerates particles such as electrons, positrons, and protons; a klystron which supplies radio frequency for accelerating the particles to the accelerating structure; a waveguide which connects together the klystron and the accelerating structure; and a pulse compressor which amplifies the high-frequency power supplied to the accelerating structure.
The accelerating structure confines an alternating electric field to the inside thereof. The accelerating structure has an elongated hollow shape formed of a plurality of annular copper discs serially connected on a common axis. Coupler cells are connected to both ends (a most upstream part and a most downstream part) of the accelerating structure, and the coupler cells are coupled to the waveguide outside the accelerating structure.
Patent Literature 1 discloses a technology concerned with an accelerating structure which uses a choke mode cavity.


An image display device comprises a frame arranged along the periphery of display screen and a plurality of detectors mounted on the frame, each for generating a detection signal in response to an object positioned outside of the frame. Each of detectors generates a detection signal indicative of the distance to an object that is present in a direction associated therewith. A control circuit selects a detection signal indicative of the shortest distance of the detection signals. The control circuit controls the direction of an image that is displayed on a display screen such that the bottom of the image is moved to a side corresponding to the detector that generates the selected detection signal.

1. Field of the Invention
The present invention relates to an image display device, and more particularly, to an image display device that can change the direction of an image, for example, rotate the image displayed on a display screen.
2. Description of the Related Art
Conventionally, a certain image display device is known to control the direction of an image displayed on its display screen such that the bottom of the displayed image is positioned at a vertically lower position of the display screen even if the display screen is rotated.
JP-2003-60940-A and JP-2003-274366-A each describe an electronic camera for controlling the direction of an image displayed on a display screen.
The electronic camera detects the posture of the electronic camera by a camera posture detector. The electronic camera records the detected posture together with an image captured by the electronic camera. Upon reproduction of the recorded image on a display screen, the electronic camera controls the direction of the image displayed on the display screen based on the detected posture that is recorded together with the image. A gravity sensor is used as the camera posture detector (see JP-2003-274366-A).
JP-H9-37187-A describes an image display device that rotates an image displayed on its display screen.
This image display device detects the posture of a user who is watching an image displayed on the image display device, instead of the posture of the image display device itself, by an infrared sensor. The image display device rotates the image displayed on the display screen by 90° when the user is sprawling. The infrared sensor senses a region in front of the display screen.
Japanese Patent No. 3013808 describes techniques for scaling up and down an image represented by an image signal.
When a gravity sensor detects the posture of an image display device as described in JP-2003-60940-A and JP-2003-274366-A, the following problems can arise.
When an image display device is installed such that its display screen is substantially horizontal to the ground surface, the result that is detected by the gravity sensor doesn't indicate the position of the user who is viewing the display screen. Therefore, the gravity sensor cannot always correctly detect the position of the user who is viewing the display screen. Accordingly, when the image display device is installed such that the display screen is substantially horizontal to the ground surface, the image display device cannot rotate a displayed image so that the user can easily watch the displayed image.
In addition, the gravity sensor cannot detect the posture of the image display device in a weightless environment such as a space station.
The image display device described in JP-H9-37187-A can arise the following problems, because the infrared sensor that is included in the image display device has a detectable region in front of the display screen.
When the image display device is installed such that the display screen is substantially horizontal to the ground surface, and when the user is watching an image displayed thereon at a position out of the front of the displayed image, the infrared sensor cannot always correctly detect the position of the user who is watching the displayed image.
FIG. 1 is an explanatory diagram illustrating an exemplary situation in which image display device 101 is installed such that display screen 102 of image display device 101 is substantially horizontal to the ground surface, and when user 201 is viewing display screen 102 at a position out of the front of display screen 102 (specifically at a position beside display screen 102).
Infrared sensor 103 has a detectable region in front of display screen 102. Therefore, in the state illustrated in FIG. 1, infrared sensor 103 cannot detect user 201. Consequently, image display device 101 cannot control the direction of an image such that the user 201 can easily watch the displayed image.

Image display device for rotating an image displayed on a display screen


Semiconductor devices and methods for manufacturing the same are disclosed. In one embodiment, the method comprises: sequentially forming a sacrificial layer and a semiconductor layer on a substrate; forming a first cover layer on the semiconductor layer; forming an opening extending into the substrate with the first cover layer as a mask; selectively removing at least a portion of the sacrificial layer through the opening, and filling an insulating material in a gap due to removal of the sacrificial layer; forming one of source and drain regions in the opening; forming a second cover layer on the substrate; forming the other of the source and drain regions with the second cover layer as a mask; removing a portion of the second cover layer; and forming a gate dielectric layer, and forming a gate conductor in the form of spacer on a sidewall of a remaining portion of the second cover layer.

With continuous scaling down of semiconductor devices, short channel effects are becoming more significant. Thus, a gate stack configuration comprising a high-K gate dielectric and a metal gate conductor is proposed. To avoid degradation of the gate stack, semiconductor devices with such a gate stack configuration are manufactured generally by means of the replacement gate process. The replacement gate process involves filling the high-K dielectric and the metal gate conductor in a gap defined between gate spacers. However, it is becoming more and more difficult to fill the high-K dielectric and the metal gate conductor in the small gap due to the scaling down of the semiconductor devices.
On the other hand, semiconductor devices formed on Extremely Thin Semiconductor On Insulator (ET-SOI) substrates have good control of the short channel effects and relatively small random fluctuation of dopants. However, the ET-SOI substrates are expensive in cost.

Semiconductor devices formed using a sacrificial layer and methods for manufacturing the same

Institute of Microelectronics, Chinese Academy of Sciences


A shower head structure characterized by comprising a shower head section, opposed to the upper surface of a mounting table in an evacuable treating vessel, for injecting a processing gas into the treating vessel; a temperature observation through-hole which opens in the lower surface of the shower head so as to be opposed to the upper surface of the mounting table, a transparent observation window which hermetically seals the upper end of the temperature observation through-hole, a radiation thermometer disposed on the upper surface of the transparent observation window, an adhesion preventive gas supply path communicating with the temperature observation through-hole to prevent a film from adhering to the transparent observation window, wherein the adhesion preventive gas supply path communicates with the temperature observation through-hole through an injection nozzle for injecting the adhesion preventive gas to the transparent observation window.

Generally, for producing a desired semiconductor device, a heat treatment such as a film forming processing or a pattern etching processing or the like is repeatedly performed on a semiconductor wafer. With a recent trend towards high-density and high-integration of a semiconductor device, a strict heat treatment method has been demanded. For example, for a very thin oxide film such as an insulating film of a capacitor or a gate insulating film in the device, the film is also required to be more thin, and at the same time, to have more superior insulation property.
As for such an insulating film, a silicon oxide film, a silicon nitride film or the like has been used. Recently, a metal oxide film, e.g., a tantalum oxide (Ta2O5) or the like, is preferably used as a material having further improved excellent insulation characteristic (e.g., Japanese Patent Laid-open Application No. H2˜283022). The metal oxide film shows reliable high insulation property even though it is thin as an oxide film conversion film.
For forming a metal oxide film having good characteristics, temperature of the semiconductor wafer needs to be very accurately controlled during the film formation. For example, a case of forming a tantalum oxide will be explained. First, a semiconductor wafer is loaded into a film forming device. As disclosed in the aforementioned application, a metal alkoxide (Ta(O2H5)5) of tantalum is used as a source for film formation. The metal alkoxide (Ta(O2H5)5) is supplied into the film forming device while being bubbled by nitrogen gas or the like. Meanwhile, the semiconductor wafer is maintained at a process temperature of, e.g., about 450° C. Further, a tantalum oxide (Ta2O5) film is deposited on the semiconductor wafer by CVD (Chemical Vapor Deposition) under a vacuum atmosphere.
As for another kind of film, an oxide film containing a plurality of metal components, i.e., so-called a multi-component metal oxide thin film, is used as a nonvolatile memory since it has ferroelectricity. As a typical example of the multi-component metal oxide thin film, a PZT film (oxide film of Pb, Zr and Ti) has been known.
In case when forming a metal oxide film, a complex metallic material film or the like, it is preferable to conduct a temperature management on the wafer. In a conventional device, a thermocouple as a temperature detection unit is provided in a mounting table (susceptor) for mounting thereon a wafer, and the temperature of the wafer is indirectly detected. Based on this detection value, an output of a heating unit such as a heating lamp, a heater or the like is controlled to thereby control the temperature of the wafer.
However, what the aforementioned thermocouple directly detects is the temperature of the mounting table, not that of the wafer as described above. Thus, a real temperature of the wafer can somewhat differ from the detection value.
For the same reason, e.g., Japanese Patent Laid-open Application No. H8˜264472, Japanese Patent Laid-open Application No. H11˜45859, Japanese Patent Laid-open Application No. H5˜152208 and the like disclose that the temperature of the wafer is measured by using a radiation thermometer without using the thermocouple. The radiation thermometer detects temperature of an object by measuring radiation brightness in a specific wavelength band from the object. By using the radiation thermometer, it is possible to directly measure the temperature of the wafer accurately without making any direct contact with the object.
However, if a residual thin film is deposited to be adsorbed on a surface of a light detector of the radiant thermometer on which an incident light of specific wavelength band from the wafer is to be illuminated, the light is absorbed by the thin film, and therefore, the radiant thermometer cannot measure the temperature of the wafer accurately. Thus, for the purpose of preventing an unnecessary thin film from being deposited on the surface of the light detector, which is exposed to a processing space while a film forming processing is performed on the wafer (or on a surface of a transparent glass plate or the like, for partitioning the incident surface from the processing space), it is preferable to supply a nonreactive gas into an observation hole, to which the radiant thermometer is attached, thereby purging a film forming gas.
However, if the nonreactive gas for preventing the deposition of the thin film is introduced into the processing space, a partial pressure of a source gas needed for forming, e.g., a metal oxide film (e.g., a source gas for pentoethoxytantalum or PZT) is lowered. As a result, a film thickness of a portion, into which the nonreactive gas is introduced, is changed, so that uniformity in the film thickness of in-surface of the wafer becomes deteriorated. Further, an increase in the amount of nonreactive gas to be used is problematic.

Shower head structure and treating device