In a server 10, a standard setting section 11 establishes a standard amount of deposits and a standard amount of money of a maintenance charge in advance; a first calculating section 12 calculates the maintenance charge by multiplying the standard amount of money by a ratio of a deposition level at returning to a standard deposition level; a memory section 13 stores in memory an engine operating time, the number of regeneration sequences performed, and a reduction coefficient table; a second calculating section 14 establishes a reduction coefficient based on the reduction coefficient table and reduces the maintenance charge after reduction by multiplying the maintenance charge calculated by the first calculating section 12 by the reduction coefficient; and a third calculating section 15 calculates an amount of refund by subtracting the value of the maintenance charge from the value of a maintenance guarantee.

1. Field of the Invention
The present invention relates to management systems for exhaust purification apparatuses. The invention relates more particularly to a management system for an exhaust purification apparatus that purifies exhaust gases by using a filter to trap particulate matter contained in the exhaust gases and regenerates the filter by burning to remove the particulate matter trapped by the filter as appropriately.
2. Description of Background Art
Construction machines, such as hydraulic excavators, are mounted with diesel engines as their drive sources. Regulations on the amount of particulate matter (hereinafter abbreviated to "PM"), together with NOx, CO, HC, and other substances, emitted from the diesel engines have been increasingly stringent year after year. In response to such a trend in these regulations, a known exhaust purification apparatus incorporates a filter called a diesel particulate filter (hereinafter abbreviated to "DPF") that traps PM to thereby reduce the amount of PM discharged externally. In this exhaust purification apparatus, the filter begins to clog as the amount of PM deposited therein increases. This causes engine exhaust pressure to increase, inviting degraded fuel efficiency. The PM trapped in the filter is then burned as appropriately to thereby remove clogging, so that the filter can be regenerated.
Regeneration of the filter is generally accomplished by using an oxidation catalyst. The oxidation catalyst may be disposed upstream of the filter, carried directly by the filter, or both. In either case, to activate the oxidation catalyst, the exhaust gas must have a temperature that is higher than an activating temperature of the oxidation catalyst. To achieve this end, a technique called active regeneration is known, in which the exhaust gas temperature is forced to increase to a level higher than the activating temperature of the oxidation catalyst. The active regeneration is achieved by several techniques, including one in which an auxiliary injection (post-injection) is performed to inject fuel in an expansion stroke following a cylinder main injection to thereby increase the exhaust gas temperature and one in which a regeneration fuel injection device disposed in an exhaust pipe is used to inject fuel into the exhaust gas that flows through the exhaust pipe, thereby increasing the exhaust gas temperature.
As a condition for starting the active regeneration, the foregoing techniques estimate the amount of PM deposited (the amount of PM trapped) in the filter. The regeneration is performed when the amount of PM deposited in the filter reaches a preset limit value for the amount of PM deposits. In this case, typically, a differential pressure across the filter is detected and the amount of PM deposits is calculated based on the detected differential pressure. The active regeneration of the filter may be automatic, in which case the active regeneration is automatically started, or manual, in which case the active regeneration is started by an operator input.
In the automatic active regeneration, a controller of the exhaust purification apparatus receives an input of a signal indicative of the amount of PM deposits and, when determining that the amount of PM deposits exceeds a threshold value, outputs a command signal for starting the regeneration. The exhaust purification apparatus then automatically starts regeneration. The exhaust purification apparatus automatically stops the regeneration after a predetermined period of time elapses or when determining that the amount of PM deposits is equal to or less than a predetermined value as a result of the burning removal.
There may still be cases in which PM is deposited without being properly burned and removed even through the automatic active regeneration depending on use conditions: for example, in cold areas or under similar conditions, the exhaust gas temperature may not increase to a level higher than the activating temperature; and the engine stops running in the middle of the automatic active regeneration. A technique is proposed that performs manual active regeneration that is started by an operator input in such cases (JP-2003-155914-A). In the manual active regeneration, the controller of the exhaust purification apparatus receives an input of a signal indicative of the amount of PM deposits and, when determining that the amount of PM deposits exceeds a threshold value, outputs an alarm signal prompting the regeneration. Noticing the alarm display, the operator operates a regeneration switch. Receiving the input of an operation signal, the controller of the exhaust purification apparatus outputs a command signal for starting the regeneration.
The current mainstream indicating the operating status of the hydraulic excavators and other construction machines is such that rental businesses purchase a large number of construction machines and rent them to customers who are engaged in civil engineering work as necessary. In this case, an operator as one of the customers operates the regeneration switch to perform the manual active regeneration. The PM trapped in the filter is burned and removed by an appropriate use of the operator. After using the hydraulic excavator, the customer returns the hydraulic excavator to the rental company. The rental company as an administrator services and maintains the hydraulic excavator before renting the same to another customer. If the amount of PM deposited in the filter is small upon returning of the hydraulic excavator, the rental company has only to perform a simple maintenance procedure for the exhaust purification apparatus.
The manual active regeneration may not, however, be performed properly despite the alarm display prompting the manual active regeneration for various reasons. Examples of the reasons include, but not limited to, the operator's inadvertently overlooking the alarm display of the manual active regeneration; the operator's being reluctant to consume extra fuel; and the operator's underestimating the importance of the manual active regeneration. If, as a result, there is a large amount of PM deposited in the filter upon returning of the hydraulic excavator, a service job for removing the PM becomes necessary, which results in an increased load of management in terms of work and time. The foregoing not only incurs maintenance cost, but also leads to reduced earnings as a result of aggravated turnover of rented machines. In the worst case, an amount of PM more than its limit is deposited in the filter, resulting in the exhaust purification apparatus failing or requiring a repair or replacement.
Specifically, if the operator fails to use the exhaust purification apparatus appropriately, increased load results on the part of the administrator in terms of work, time, and expenditure.

Management system and method for exhaust purification apparatus

Hitachi Construction Machinery Co., Ltd.


A mechanism is presented for attributing users to one or more of a plurality of sub-bands in a multiple access communications system, wherein in an initial assignment phase, a first user is selected for a sub band, for example on the basis of a user priority. Users having complementary channel gains to that of the first user are identified, and then a second sub-band user maximizing a performance metric reflecting the achieved throughput, and/or fairness across users, is selected to accompany the first user on that sub-band. The initial assignment phase may terminate once all users have been assigned to a sub-band once. After the first phase is complete, the first user for each sub-band may be the user whose achieved total throughput is furthest from a target throughput defined for that user, wherein each user is assigned to the remaining sub-band to which no first user is currently attributed offering the highest channel gain for that user. Mechanisms for determining user priority, making provisional and definitive power allocations, and performance metrics are proposed.

With the proliferation of internet applications, it is expected that the mobile traffic volume supported by communication networks increases by 8 times between the end of 2016 and 2022. To respond favourably to such constraints while keeping a high level of user quality of experience, system capacity and user fairness should be largely improved for the future 5th generation (5G) mobile communication systems. To this end, Non-Orthogonal Multiple Access (NOMA) has recently emerged as a promising candidate for future radio access. By exploiting an additional multiplexing domain, the power domain, NOMA allows the cohabitation of multiple users per sub-band at the transmitter side, on top of the modulation layer which may be Orthogonal Frequency Division Multiplex (OFDM), Filter Bank Multi-Carrier (FBMC), Universal Filtered Multi-Carrier (UFMC), or other multiple carrier scheme, and relies on an interference cancellation technique at the receiver side, such as Successive Interference Cancellation (SIC). An attractive feature of NOMA is that it targets the increase of system capacity while improving user fairness. Therefore, most of the prior art dealing with NOMA considers the proportional fairness (PF) scheduler as a multiuser scheduling scheme for the trade-off between total user throughput or data rate and the user fairness that it provides. Examples of power allocation algorithms, jointly implemented with a NOMA-based PF scheduler used for the selection of users to be assigned to each sub-band are presented for example in "Uplink non-orthogonal access with MMSE-SIC in the presence of inter-cell interference" by Y. Endo, Y. Kishiyama, and K. Higuchi. in proc. 2012 IEEE Int. Symp. on. Wireless Commun. Syst, 2012, or "System-Level Performance of Downlink Non-orthogonal Multiple Access (NOMA) Under Various Environments" by Y. Saito, A. Benjebbour, Y. Kishiyama, and T. Nakamura in proc. IEEE 81st VTC, 2015.
In the article drafted by by Umehara, J., Kishiyama, Y., Higuchi, K. entitled "Enhancing user fairness in non-orthogonal access with successive interference cancellation for cellular downlink", in Proc. International Conference on Communication Systems (ICCS 2012), the authors propose a weighted PF-based multiuser scheduling scheme in a non-orthogonal access downlink system. A frequency block access policy is proposed for cell-interior and cell-edge user groups in fractional frequency reuse (FFR), with significant improvements in the user fairness and system frequency efficiency.
In the article by Mehrjoo, M., Awad, M. K., Dianati, M., Xuemin, S., entitled "Design of Fair Weights for Heterogeneous Traffic Scheduling in Multichannel Wireless Networks," IEEE Trans. Commun., 58(10) (2010), fair weights have been implemented for opportunistic scheduling of heterogeneous traffic types for OFDMA networks. For designing fair weights, the proposed scheduler takes into account average channel status and resource requirements in terms of traffic types. Simulation analysis demonstrates the efficiency of the proposed scheme in terms of resource utilization, and flexibility to network characteristics change due to user mobility.
In the article from Gueguen, C., Baey, S., entitled "Compensated Proportional Fair Scheduling in Multiuser OFDM Wireless Networks", in Proc. IEEE International conference on Wireless Mobile Computing, Networking Communication (2008), the problem of fairness deficiency encountered by the PF scheduler when the mobiles experience unequal path loss is investigated. To mitigate this issue, a modified version of the PF scheduler that introduces distance compensation factors has been proposed. It was shown that this solution achieves both high capacity and high fairness.
In the article by Yang, C., Wang, W., Qian, Y., Zhang X., entitled "A Weighted Proportional Fair Scheduling to Maximize Best-Effort Service Utility in Multicell Network, in Proc. IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (2008), a weighted proportional fair algorithm is proposed in order to maximize best-effort service utility. The reason behind introducing weight factors to the PF metric is to exploit the inherent near-far diversity given by the path loss. The proposed algorithm enhances both best-effort service utility and throughput performance while maintaining similar complexity when compared to the PF metric.
If a downlink system with a single transmitter and receiver antenna is considered, the system consists of K users per cell, with a total system bandwidth B divided into S sub-bands, and a maximum allowable transmit power Pmax by the Base Station. Among the K users, a set of users Us={k1, k2, . . . , kn, . . . , kN}, is selected to be scheduled over each frequency sub-band s, (1≤s≤S). N indicates the number of users non-orthogonally scheduled on a sub-band. The Successive Interference Canceller (SIC) process as described in Fundamentals of Wireless Communication, Cambridge University Press, 2005 by D. Tse, and P. Viswanath, is conducted at the receiver side, and the optimum order for user decoding is in the increasing order of the channel gains observed by users, normalized by the noise and inter-cell interference
      h       s    ,         k     n          2       n       s    ,         k     n          where hs,kn2 is the equivalent channel gain at sub-band s, between user kn and the base station BS, and ns,kn the average power of the Gaussian noise plus intercell interference received by user kn. Assuming successful decoding and no SIC error propagation, and supposing that inter-cell interference is randomized such that it can be considered as white noise, the throughput of user kn, at sub-band s, Rs,kn, is given by:
                     R             s       ,               k        n                       =                  B       S                                 log        2              (               1        +                                      h                       s            ,                         k             n                                  2                                         P                       s            ,                         k             n                                                                                ∑                                                      k               j                            ∈                             U               s                                        ,                                                          h                                 s                 ,                                   k                  n                                                 2                                              n                                 s                 ,                                   k                  n                                                                            <                                             h                                 s                 ,                                   k                  j                                                 2                                              n                                 s                 ,                                   k                  nj                                                                                h                           s              ,                             k               n                                        2                                                 P                           s              ,                             k               j                                                                      +                     n                       s            ,                         k             n                                                                )                              Eq     .                   (      1      )               WhereK is the number of users per cell,B is the total system bandwidth,kn is a user n of K,N is the number of users non-orthogonally scheduled on a sub-band,Us={k1, k2, . . . , kn, . . . kN}, is the set of users selected to be scheduled over each frequency sub-band,kj considers the users of Us having a channel gain greater than kn,S is the number of sub-bands in the system,s is the sub band under consideration (1≤s≤S).Pmax is the maximum allowable transmit power,
      h       s    ,         k     n          2       n       s    ,         k     n          is the squared channel gain observed by user kn, normalized by the noise and inter-cell interference where hs,kn is the equivalent channel gain at sub-band s, between user kn and the base station BS, and ns,kn the average power of the Gaussian noise plus intercell interference received by kn, at sub-band s,and Rs,k(t) represents the throughput of user k on sub-band s.
The transmit power allocation constraint is represented by:
                                    ∑                 s         =         1                S                      P        s                   =             P       max                ,                  with                                P        s                   =                     ∑                 n         =         1                N                      P                 s         ,                   k          n                                                      (     2     )          Where Ps denotes the amount of allocated power on sub-band s.
Since the scheduler in NOMA may allocate a sub-band to more than one user simultaneously, the user scheduling policy affects system efficiency and user fairness as different policies may lead to preferential treatment of certain users in the interest of improved overall throughput, even if this means degraded service for other users, or vice versa.
The "Proportional Fairness" (PF) scheduler as introduced by the prior art references above is considered to achieve a trade-off between these two metrics. The objective of the PF scheduler is to maximize the long term averaged user rates, in order to ensure balance between cell throughput and user fairness. The PF algorithm is used in LTE (Long Term Evolution) for user scheduling (assignment of users to time-frequency resource blocks).
The operation of the PF scheduler is as follows: at the beginning of each scheduling slot t, each user provides the base station (BS) with its channel state. The BS can then compute the achievable throughput for each user (depending on the adopted power allocation strategy). The PF scheduler (operating at the BS side) keeps track of the average throughput achieved by each user in a past window of length tc and gives each user a priority inversely proportional to its average throughput.
At the beginning of each scheduling time slot t, each user k provides the base station with its channel gain on each sub-band s, s=1 . . . S.
The base station computes the corresponding achievable throughput for user k on sub-band s, Rs,k(t).
At a time slot t, user k* is selected to be served on sub-band s based on:
                     k      *          =                                   arg                              max                                       k        =                 1                  …                  K                                                         R                   s          ,          k                         (        t        )                               T         k                (        t        )                                     (     3     )
A scheduler applying this approach gives each user a priority inversely proportional to its historical rate Tk(t). If Tk(t) is high, user k will possibly not be assigned any transmission rate for several time slots. This is problematic for applications requiring quasi-constant Quality of Experience (QoE), and may call for deep buffering. By the same token, this approach may raise difficulties for applications requiring low latency transmission.
The PF scheduling algorithm was initially devised for orthogonal multiple access schemes (OFDMA in LTE) but was later adapted for Non-Orthogonal Multiple Access (NOMA) schemes.
This scheduling policy has been adopted in the majority of proposed NOMA implementations. The scheduling algorithm keeps track of the average throughput Tk(t) of each user in a past window of length tc, where tc defines the throughput averaging time window (over a specified number of previous time slots). Tk(t) is defined as:
                            T       k            (             t       +       1            )          =                          (                 1         -                   1                     t           c                                   )                                      T         k                (        t        )                   +                     1                 t         c                                              ∑                   s          =          1                  S                                   R                     s           ,           k                            (         t         )                                             (     4     )          where Rs,k(t) represents the throughput of user k on sub-band s, at time instance t. Rs,k(t) is calculated based on Eq. (1) above, and can equal zero if user k is not scheduled on sub-band s.
In the case of NOMA, where N>1, the possible candidate user sets are enumerated:
   C  =     (                  N                        K               )   combinations U of N users among K
At the beginning of each scheduling time slot t, each user k provides the base station with its channel gain on each sub-band s, s=1 . . . S. For each candidate user set U (U∈{U1, . . . ,Uc}) on sub-band s, the base station computes the corresponding throughput for user k in set U, Rs,k|U(t).
At time t, the selected user set is:
                     U      s          =                          arg                           max                      U        ∈                 {                              U           1                              …                               U           C                            }                                                ∑                 k         ∈         U                                                 R                     s           ,                       k            |            U                                       (         t         )                                   T          k                  (         t         )                                             (     5     )          Where Rs,k|U(t) is the achievable throughput of user k on sub-band s at time t, considering user set U, Tk(t) is the average throughput of user k in a past window of length tc, considering all the sub-bands (historical rate or throughput) and assuming the available frequency band B is divided into S sub-bands, the total number of users willing to communicate is K, the number of users on sub-band s is N (in OMA N=1, in NOMA N>1), and the total power budget is Pmax. At the beginning of the scheduling process, all the users have throughput equal to 0, and at the beginning of each scheduling time slot t, each user k provides the base station with its channel gain on each sub-band s, with s=1 . . . S, hs,k(t), and the average throughput Tk(t) of user k is computer for a past window of length tc, considering all the sub-bands (historical rate or throughput).
The PF scheduler targets long-term fairness. Since the PF scheduler gives each user a priority inversely proportional to its average throughput, it happens that some users do not gain access to available resources whenever their historical rate is high. In such a case, the users will not be assigned any transmission rate for multiple scheduling slots. This behaviour can be very problematic in applications with constraints on user throughput (e. g. quasi-constant data rate applications), or where deep buffering may be needed, and may not be compatible with applications requiring low latency transmission. Moreover, for NOMA schemes, the PF scheduler does not take account of a NOMA specificity: the overall throughput achieved in NOMA systems increases with the difference in channel gains of paired users.
In general, when using PF scheduling for user allocation in NOMA schemes, a large user throughput gain can be observed for users located near the base station compared to orthogonal multiple access (OMA) schemes, but almost no gain is achieved for cell edge users.
It is thus desirable to identify a mechanism for resolving these issues and in particular providing a method for a better attribution of users.

Method and apparatus for user distribution to sub-bands in multiple access communications systems


An object of the invention is to provide a foldable electronic apparatus capable of exhibiting satisfactory acoustic characteristics even if the body is thinned and its internal space is made small. In an electronic apparatus according to the invention, a first casing (1) and a second casing (2) can be folded together along a bearing portion (3) and the front face and the back face of one of the first and second casings ((1) or (2)) are formed with respective sound emission holes (8) and (6) that are opposed to each other. A speaker (7) is provided at a position corresponding to the sound emission holes (8) and (6), and the front face of the other body ((2) or (1)) is formed with a through hole (9) that is opposed to the sound emission hole (8) in a state that the first and second casings (1) and (2) are folded together.

As shown in FIGS. 4-6, for convenience in carrying, an electronic apparatus such as a PDA, a cell phone, or a simplified cell phone (PHS (registered trademark)) generally employs a structure in which a first casing 11 incorporating a display 14 and a second casing 12 incorporating a keyboard 15 are attached so as to freely rotate to each other by a bearing portion 13, and the first casing 11 and the second casing 12 can be folded together. When the electronic apparatus has a foldable structure, it is necessary that a speaker 16 for emitting a ringing sound be provided so as to be directed outward in the state that the first casing 11 and the second casing 12 are folded together so that a sufficiently loud ringing sound is emitted outward even in the state that the first casing 11 and the second casing 12 are folded together. For example, as shown in FIG. 6, the face of the first casing 11 that is opposite to the face having the display 14 is formed with a sound emission hole 17 and the speaker 16 for emitting a ringing sound is provided in the first casing 11 so as to be opposed to the sound emission hole 17.
However, in recent years, the thickness of electronic apparatus of the above kind has decreased rapidly and the display 14 has come to be required to be large. As a result, the internal space of the first casing has become very small. This raises a problem that the driving of the speaker 16 itself is made difficult and hence satisfactory characteristics cannot be obtained.
The present invention has been made in view of the above problems in the art, and an object of the invention is to provide a superior electronic apparatus capable of securing satisfactory characteristics all the time even with a simple structure.

Matsushita Electric Industrial Co., Ltd.


A method and system for creating a database for diagnosis determination that includes receiving baseline symptoms in a memory, receiving diagnoses in the memory, classifying the diagnoses that correspond to the baseline symptoms as diagnoses linked to the baseline symptoms, and rendering the diagnoses accessible on the basis of the corresponding baseline symptoms. A method and system for determining a diagnosis and treatment that includes receiving patient symptoms, comparing patient symptoms to previously stored baseline symptoms, identifying the patient symptoms that correspond to the baseline symptoms, and providing diagnoses that correspond to the identified patient symptoms to a user.

1. Field of the Invention
The present invention relates to a method and system for diagnosis of a patient based on the patient's symptoms. Specifically, the present invention relates to a method and system for the automated determination of the appropriate diagnosis of a patient on the basis of the patient's symptoms.
2. Background of the Related Art
As it may be difficult for elderly people, people with disabilities or poor people to have access to a doctor in an adequate or optimal amount of time, a medical system for automatic diagnosis of patients is becoming increasingly desirable. For example, Akasaka et al. (U.S. Pat. No. 5,785,650), which is incorporated herein by reference in its entirety, teaches an integrated medical system that allows the transmission of patient data via a network to a remote medical practitioner.
A patient can utilize such a prior art system while being at home. Such a prior art system allows data, such as blood pressure and electrocardiogram output, to be automatically transmitted. Such a system also allows the patient to input personal data, such as body weight, via a keyboard at a communication terminal or to provide his/her answers to questions posed to the patient by the system.
On the other hand, Walker et al. (U.S. Pat. No. 6,302,844), which is incorporated herein by reference in its entirety, teaches a method and apparatus for analyzing data from remote monitoring equipment and determining whether an anomalous event has occurred, and whether the anomalous event warrants contacting a physician. Morris et al. (U.S. Patent Application No. 2004/0078227), which is incorporated herein by reference in its entirety, teaches a system and method that are used for creating a longitudinal medical record for an injured person and includes a plurality of mobile computing devices having an interface for receiving information from a first responder or a health care practitioner.
However, none of the se systems provide an automated diagnosis method and system that provides a patient with a viable diagnosis and treatment on the basis of symptoms and other information provided by the patient.

Integrated method and system for diagnosis determination


Disclosed is a motion estimation apparatus and method capable of reduce a memory bandwidth by accessing reference image data occupying the largest part of the memory bandwidth based on a result of motion estimation skip determination. The motion estimation apparatus includes a motion estimation skip determination unit, a sum absolute of absolute difference (SAD) processing unit and a multiplexer (MUX) unit. The motion estimation skip determination unit determines the presence of motion estimation skip by reading current image data and skip reference image data, and outputs a motion vector in a skip mode. The SAD processing unit calculates an SAD value by reading the current image data and reference image data and outputs a motion vector in a normal mode. The MUX unit outputs the motion vector in the skip mode or the motion vector in the normal mode as a final motion vector based on a skip flag signal.

Exemplary embodiments of the present invention relate to a motion estimation apparatus and method, and more particularly, to a motion estimation apparatus and method capable of decreasing memory bandwidth in motion estimation for image compression.
H.264 is a standard jointly developed by the Video Coding Experts Group (VCEG) of the International Telecommunications Union (ITU) and the Moving Picture Experts Group (MPEG) of the International Standard Organization (ISO), which establish international standards for moving pictures. H.264 is aimed at achieving a very high compression ratio and is a general-purpose moving picture coding technique that can be used in most transmission media such as recording media, the Internet, satellite broadcasting, etc., and in various moving picture resolution environments.
Traditionally, ITU has established moving picture standards such as H.261, H.263 and H264, on the basis of wired communication media, and MPEG has standardized MPEG-1, MPEG-2 and the like as standards for processing moving pictures in recording media and broadcasting media.
The MPEG has also standardized an MPEG-4 moving picture standard that is a coding standard used in all types of multimedia, and implements various functions characterized by an object-based moving picture code and a high compression ratio. After the establishment of the MPEG-4 moving picture standard, the VCEG of ITU went on to establish a moving picture standard known as H.26L with high compression performance. In MPEG's official comparison test, H.26L, having the same function as MPEG-4 (advanced simple profile), exhibited a superior compression ratio to MPEG-4.
As a result of the test, the MPEG and the VCEG of ITU joined to form the Joint Video Team (JVT) and developed H.264/Advanced Video Coding (AVC) that is a moving picture standard based on H.26L.
The H.264/AVC has a variety of excellent characteristics. Current markets require a System on Chip (SoC) capable of performing processing with high image quality and high resolution. As the resolution increases, data transmissions between external and internal memories frequently occur, which results in performance degradation of the entire system.
The technical configuration described above is a background art for better understanding of the present invention, but is not a prior art well-known in the technical field pertinent to the present invention.

Electronics and Telecommunications Research Institute


A separator of the invention is designed to remove foreign materials, such as small stones, included in granulated materials, such as red beans, having smooth outer surfaces. The separator is formed of a supplying section, and a separating section for receiving the granulated materials with the foreign materials from the supplying section and separating the foreign materials from the granulated materials. The separating section includes at least one pair of elongated rollers formed of first and second rollers, which are arranged parallel to and at a predetermined distance spaced apart from each other. The first roller has a spiral projection on an outer surface thereof. When the granulated materials with the foreign materials are supplied onto one end of the pair of the rollers, the foreign materials are caught between the rollers and dropped downwardly, while the granulated materials are transferred to the other end of the rollers by the rotating spiral projection and are collected.

The present invention relates to a separator for removing foreign materials, such as sands and small stones, contained in granulated or round materials, such as red beans, soybeans, sesame seeds, pepper corns and so on, packed in a bag.
In a packed granulated materials like red beans, foreign materials like small stones may be included. If the granulated materials are utilized or cooked as they are without removing the foreign materials, a product made by the granulated materials inevitably contains the foreign materials, which is not preferable.
For example, in case red beans are boiled and cooked for food, if foreign materials, such as small stones, are contained in packed red beans, the foreign materials may be included in the food. Thus, conventionally, when red beans are taken out of a pack, at first, the foreign materials, such as small stones, are removed by hands of a person, and after removing the foreign materials, red beans are boiled.
Removal of the foreign materials by hands is very troublesome. In order to reduce labour for this removal operation, the present inventors completed a device disclosed in Japanese Utility Model Application No. 62-14121.
In the device of Application No. 62-14121, for example, since red beans are transferred only by inclination of rollers, if red beans have shapes to be easily rotatable, red beans are transferred to the end of the rollers in a short period of time, so that the foreign materials removing operation can not be made sufficiently. Also, since the transfer of red beans on the rollers is made only by inclination of the rollers, the smooth transfer can not be made. Further, in case the device is stopped in a middle of the operation, red beans may still be transferred by rotation thereof due to inclination of the rollers.
The present invention has been made to obviate the problems, and is an improvement of Japanese Utility Model Application No. 62-14121.
Accordingly, one object of the invention is to provide a separator for efficiently removing foreign materials from granulated materials with smooth outer surfaces.
Another object of the invention is to provide a separator as stated above, wherein the foreign materials can be removed regardless the size thereof.
A further object of the invention is to provide a separator as stated above, wherein the foreign materials can be removed from various sizes of the granulated materials.
Further objects and advantages of the invention will be apparent from the following description of the invention.

Separator for removing foreign materials in granulated materials


A disc brake includes a carrier with an inner beam secured to a knuckle, a pair of in board and outboard brake pad assemblies located on opposite sides of a rotor and slideably supported on the carrier, and a caliper extending over the periphery of the rotor and axially moved to urge the in board and outboard brake pad assemblies into frictional engagement with the opposite sides of the rotor. The carrier is constructed so that the difference in natural frequency between a bending mode and a torsion mode is at least 300 Hz. The carrier has a moment of inertia of area/polar moment of inertia of area ratio of at least 0.75.

The present invention relates to disc brakes for use on automotive vehicles.
A known disc brake for a motor vehicle typically includes a pair of in board and outboard brake shoes or pad assemblies placed on opposite sides of a rotor rotatable with a wheel to be braked and slideably supported on a carrier secured to a non-rotatable part of the vehicle. When a brake pedal is depressed, a caliper is moved on the carrier to urge the in board and outboard pad assemblies into frictional engagement with opposite sides of the rotor so as to apply the necessary clamping force thereto.
A problem associated with such a conventional disc brake is the frequent occurrence of a low frequency noise or squeal when the pad assemblies are pressed against the rotor. Such a noise is obviously uncomfortable to the driver. There is thus a need to substantially reduce the number of occurrences of such a low frequency noise.
An attempt has been made to reinforce the most deformed part of a carrier to increase its rigidity, as disclosed in Japanese laid-open patent publication No. 7-259901. This attempt is effective in reducing the extent of vibrations, but fails to reduce the number of occurrences of a low frequency noise (see FIG. 7).
Through an extensive search, the inventor has found that the occurrence of a low frequency noise of, for example, 1.8 kHz, is more closely related to vibrations of a carrier than to any other part of a disc brake. The carrier has various modes of vibration such as bending and torsion modes of vibration. The carrier typically includes a pair of inner arms located on the in board side of a rotor and having a pair of guides along which an in board brake pad assembly is axially moved, a pair of outer arms located on the outboard side of the rotor and having a pair of guides through which an outboard brake pad assembly is axially moved, an inner beam extending between the two inner arms and secured to a knuckle or other fixed part of a vehicle, and an outer beam extending between the two outer arms. In the torsion mode, the inner arms are twisted in opposite directions. This is also the case with the outer arms. In the bending mode, the inner and outer arms are bent about an axis parallel to the axis of the rotor. It has been found that these two different modes of vibration interact to cause a self-exited vibration and thus, a low frequency squeal.
In the disc brake shown in Japanese laid-open patent publication No. 7-259901, the difference in natural frequency between the bending and torsion modes is even less than that of the typical carrier known in the art (see FIG. 7). It is believed that an increase in rigidity of the carrier does not bring about a reduction in the number of occurrences of the low frequency noise.
Accordingly, it is an object of the present invention to provide a disc brake which enables a substantial reduction in the number of occurrences of a low frequency noise or squeal without the need for additional parts and without increasing its production cost and weight.


A new cultivar of Heliconia plant named ‘Lars’ that is characterized by a compact habit and small orange flowers that bloom throughout the entire year.

The present invention relates to a new and distinct cultivar of Heliconia plant botanically known as Heliconia psittacorum and hereinafter referred to by the cultivar name 'Lars'.
The new cultivar was discovered as a naturally occurring whole plant mutation in a cultivated area of Enkhuizen, The Netherlands. The exact parent plant is unknown. The cultivar 'Lars' was discovered by the inventor in 1999 as a single plant.
Asexual reproduction first occurred when rhizomes of the new cultivar 'Lars' were propagated in 2000 in Enkhuizen, The Netherlands. Since that time, under careful observation, the unique characteristics of the new cultivar have been uniform, stable and reproduced true to type in successive generations of asexual reproduction.


A system for giving meaning to data in a non-standardized digital document. In some embodiments, the system includes a web portal, a recognition server and an extraction system. The web portal is accessible via a network for receiving a non-standardized digital source document. The recognition server is configured to perform optical character recognition analysis on the non-standardized digital source document and generates document recognition data including positional locations of a plurality of characters in the non-standardized digital source document. The extraction system is configured to identify labels and corresponding values represented in the non-standardized digital source document and automatically maps the labels to a plurality of predetermined variables in an external software system to which the values from the non-standardized digital source document are to be imported.

Some digital documents are natively electronic while others originate as paper documents that were digitized. For example, some electronic documents are created by scanning paper documents. Unlike native documents, scanned documents are typically an image file, which is essentially a photo of the paper document.
Optical character recognition ("OCR") can be used to convert the image file of the document into machine-encoded text. The resulting file is merely the translation of characters from the image file, but does not provide any meaning of the characters in the file. For example, the OCR file may have converted the characters "assets" and "$1,000," but there will be no relationship created between this data in which the variable "assets" is assigned a value of "1,000."
Determining the meaning of data in an OCR file can be important. For example, the meaning may be needed for importation of the data into a third party software system. With such an import, determining where values are positioned for which variables can be difficult. Typically, the document must be mapped to establish the locations of the values for each variable needed in the import. This type of mapping can be time consuming and costly. In cases where the documents are in a standardized format, such as a standard form, each form can be mapped and used to extract data from multiple documents having that standardized format. With non-standardized documents, however, the mapping of each document is generally not feasible because the location of values and variables is unexpected.
This disclosure relates to an automated solution for extracting this data from non-standardized financial documents (e.g., balance sheets, income statements, etc.) for import into financial software systems. The system includes a portal that allows a financial institution's customers to submit financial documents. The system allows a software subscriber to setup recurring mapping rules based upon the contents of the submitted statements, apply these mapping rules to statements each time they are submitted, and produce an extract of data formatted for integration into financial institutions' internal systems. Since this process is automated, the system creates an audit trail each step of the way to provide compliance-oriented monitoring over the data flow from their end-customer into the financial institution.
The system uses existing OCR technologies to map the contents of financial documents' pages. However, this map is consumed by the system with a custom interpreter that makes assumptions based on the fact that the scanned documents are financial statements that typically have some common formatting features. These assumptions allow the system to make sense of financial statements and extract the data properly without an extensive OCR mapping process that is common in OCR scenarios. In other words, the system can make sense of the OCR'ed data to assign certain numbers to variables for export and allows data to be extracted from these statements the first time it is submitted without an expensive one-time effort to setup a specific template for the statement which allows the system to read it with conventional OCR interpreter technologies.


Provided herein are methods of forming thin films. In some embodiments, to form a thin film, a precursor adsorption layer including an organic ligand is formed by supplying a precursor including a metal or silicon central atom, and the organic ligand onto a lower structure. An intermediate result layer is formed by supplying a non-oxidant onto the precursor adsorption layer. In forming the intermediate result layer, the organic ligand included in the precursor adsorption layer is substituted with a substituent. An oxide film including the central atom is formed from the intermediate result layer by supplying an oxidant onto the intermediate result layer.

Along with producing more highly integrated and finer electronic devices, patterns included in the electronic devices have increasingly larger aspect ratios. Deposition techniques that can provide excellent filling properties and excellent step coverage even in a narrow deep space having a large aspect ratio may be desirable. In particular, in performing an atomic layer deposition (ALD) process for forming a thin film on a deep narrow 3-dimensional structure, it may be desirable to develop techniques of forming a thin film having desired properties.

Methods of forming thin films and methods of fabricating integrated circuit devices using the same


A duplexer includes a first band-pass filter and a second band-pass filter with a pass-band lower than the first band-pass filter. The first band-pass filter includes an unbalanced surface acoustic wave filter. First, second and third signal wire electrodes and a ground wire electrode are provided on a piezoelectric substrate in the first band-pass filter, and a bridging area is provided where any one of the first, second and third signal wire electrodes bridges the ground wire electrode. A width of a portion of the signal wire electrode that opposes the ground wire electrode with an interlayer insulating film located therebetween is greater than a width of a portion of the signal wire electrode other than the bridging area so that a low-pass filter capacitor is provided.

1. Field of the Invention
The present invention relates to duplexers including first and second band-pass filters that have different pass-bands, and particularly relates to duplexers in which the first band-pass filter includes an unbalanced surface acoustic wave filter.
2. Description of the Related Art
Various duplexers that use surface acoustic wave filters have been proposed thus far. For example, Japanese Unexamined Patent Application Publication No. 2000-349591, described hereinafter, discloses a SAW duplexer including a transmission filter and a reception filter. In Japanese Unexamined Patent Application Publication No. 2000-349591, the reception filter is configured of a longitudinally coupled resonator-type surface acoustic wave filter. The reception filter configured of a longitudinally coupled resonator-type surface acoustic wave filter described in Japanese Unexamined Patent Application Publication No. 2000-349591 has an unbalanced input terminal and an unbalanced output terminal. In other words, the reception filter is an unbalanced surface acoustic wave filter.
Thus far, the stated unbalanced surface acoustic wave filter and a balanced surface acoustic wave filter that can obtain a balanced output have been known as surface acoustic wave filters used as reception filters in duplexers. The balanced surface acoustic wave filter can increase harmonic attenuation through balance between balanced output terminals.
On the other hand, in the case where an unbalanced surface acoustic wave filter such as that described in Japanese Unexamined Patent Application Publication No. 2000-349591 is used, it has been difficult to increase the harmonic attenuation. When the harmonic attenuation is low, there is a risk that a noise signal outputted from a voltage controlled oscillator (VC) will combine with the harmonic, resulting in an unnecessary signal being produced. There is thus a risk that the reception sensitivity will drop.

Duplexer including a low-pass filter capacitor


A string matching system includes a text string, a plurality of patterns, an m-byte search window and a plurality of Bloom filters, wherein the m-byte search window stands for an m-byte sub-string in the text string under inspection. Every Bloom filter comprises sub-strings of a plurality of patterns. These Bloom filters are queried for membership of the rightmost block in the search window to determine the shift length. The acceleration efficiency of matching many bytes can be achieved simultaneously by shifting the search window for many bytes. Meanwhile, the patterns are stored into an embedded memory through a memory-efficient mechanism —the Bloom filter.

1. Field of the Invention
The present invention generally relates to a string matching system and its method, and more particularly to the system and the method, which employ a plurality of Bloom filters for matching the strings and decide the shift distance of the search window to achieve the goal of accelerating hardware (HW) within sub-linear computation time.
2. Description of Related Art
While more and more people gain access to the Internet, there is ever-growing information flowing across the network. However, potential network intrusion and attack pose negative influences upon computer and network systems. For example, a variety of servers or even PCs (personal computers) are vulnerable to viruses.
In recent years, many safety-related information systems, such as a Network Intrusion Detection System (NIDS) and an antivirus system have become an important safety-related network technology, in which the matching efficiency of network packet content is decisive to the system performance. In the event of slow matching speed on strings, the network-dependent tasks may not be performed on time, so the failures of detecting network intrusion or viruses increases to a great extent. A sub-linear time algorithm can skip characters not in a match during scanning for signatures of intrusions and viruses. Therefore, it can be very efficient for signature matching. FIG. 1 depicts the flow process of a typical sub-linear time string matching method, of which the matching steps include:
Step S11: Start;
Step S12: Build up a block containing the last bytes in the search window, and look it up in the shift distance table to obtain a shift length N;
Step S13: Check if shift length is 0; if yes, perform Step S15, otherwise, perform Step S14;
Step S14: Shift forward the search window for the distance implied from the table lookup, and return to Step S12;
Step S15: Compare the hash value table that contains the pattern set;
Step S16: Check if a string in the table is the same; if yes, perform Step S17, otherwise, perform Step S18;
Step S17: Set the successful matching flag as true;
Step S18: Shift forward 1 byte for the sliding window, and return to Step S12; and
Step S19: Output.
The shift length of the search window is generally decided by means of looking up the shift distance table. This requires a large memory space to store the shift length for every block. When a small block is used to reduce the table space, frequent verification may be required, thus leading to slower matching speed and poorer matching efficiency. To overcome the aforementioned problems of the prior art, it would be an improvement if the art provides a better structure that can significantly improve the efficacy.
To this end, the inventor has provided the present invention of practicability after deliberate design and evaluation based on years of experience in the production, development and design of related products.

String matching system and method using bloom filters to achieve sub-linear computation time


An organic thin film transistor comprising a self-assembled monolayer interposed between a gate dielectric and an organic semiconductor layer. The monolayer is a product of a reaction between the gate dielectric and a precursor to the self-assembled monolayer. The semiconductor layer comprises a material selected from an acene, substituted with at least one electron-donating group, halogen atom, or a combination thereof, or a benzo-annellated acene or polybenzo-annellated acene, which optionally is substituted with at least one electron-donating group, halogen atom, or a combination thereof. Methods of making a thin film transistor and an integrated circuit comprising thin film transistors.

This invention relates to organic thin film transistors having improved performance. More particularly, the invention relates to organic thin film transistors having a substituted acene semiconductor and a self-assembled monolayer between the semiconductor and gate dielectric.
Organic semiconductors are of great interest for a variety of applications such as low-cost electronics. Organics can be synthesized to incorporate the necessary electronic properties for a wide variety of devices, and also can be constructed to allow low-cost, roll processing that is not currently possible for crystalline silicon microelectronics.
One area of concern in organic electronic devices is the quality of the interface formed between the organic semiconductor and another device layer. Previous efforts to control the semiconductor/dielectric interface have included the use of hexamethyldisilazane (HMDS) and silane coupling agents on silicon oxide surfaces. Complex deposition processes involving long times in a vacuum have been used to coat octadecyltrichlorosilane (OTS) onto thermally-grown silicon dioxide gate dielectric materials to affect transistor performance. The materials useful in this process have several disadvantages, including sensitivity to water in the atmosphere and on the surface of a dielectric layer, instability due to crosslinking within the material in competition with the bonding reaction to the dielectric layer, and difficulties in achieving reproducible film properties. EP 1041652 A2 describes the use of several surface treatments to enhance the crystalline domain size of solution cast oligothiophenes on SiOx for thin film transistors (TFTs), although measured mobility values were generally lower than the untreated controls.
Briefly, the present invention provides an organic thin film transistor (OTFT) comprising a self-assembled monolayer interposed between a gate dielectric and an organic semiconductor layer, the monolayer being a product of a reaction between the gate dielectric and a precursor to the self-assembled monolayer, the precursor comprising a composition having the formula:
Xxe2x80x94Yxe2x80x94Zn,
wherein X is H or CH3;
Y is a linear or branched C5-C50 aliphatic or cyclic aliphatic connecting group, or a linear or branched C8-C50 group comprising an aromatic group and a C3-C44 aliphatic or cyclic aliphatic connecting group;
Z is selected from xe2x80x94PO3H2, xe2x80x94OPO3H2, benzotriazolyl (xe2x80x94C6H4N3), benzotriazolylcarbonyloxy (xe2x80x94OC(xe2x95x90O)C6H4N3), benzotriazolyloxy (xe2x80x94Oxe2x80x94C6H4N3), benzotriazolylamino (xe2x80x94NHxe2x80x94C6H4N3), xe2x80x94CONHOH, xe2x80x94COOH, xe2x80x94OH, xe2x80x94SH, xe2x80x94COSH, xe2x80x94COSeH, xe2x80x94C5H4N, xe2x80x94SeH, xe2x80x94SO3H, xe2x80x94NC, xe2x80x94SiCl(CH3)2, xe2x80x94SiCl2CH3, amino, and phosphinyl; and n is 1, 2, or 3 provided that n=1 when Z is xe2x80x94SiCl(CH3)2 or xe2x80x94SiCl2CH3; and wherein the organic semiconductor layer comprises a material selected from an acene, substituted with at least one electron-donating group, halogen atom, or a combination thereof, or a benzo-annellated acene or polybenzo-annellated acene, which optionally is substituted with at least one electron-donating group, halogen atom, or a combination thereof.
The present invention also provides an organic thin film transistor comprising a self-assembled monolayer interposed between a gate dielectric and an organic semiconductor layer, the monolayer being a product of a reaction between the gate dielectric and a precursor to the self-assembled monolayer, the precursor comprising a composition having the formula:
Xxe2x80x94Yxe2x80x94Zn,
wherein X is H or CH3;
Y is a linear or branched C5-C50 aliphatic or cyclic aliphatic connecting group, or a linear or branched C8-C50 group comprising an aromatic group and a C3-C44 aliphatic or cyclic aliphatic connecting group;
Z is selected from xe2x80x94PO3H2, xe2x80x94OPO3H2, benzotriazolyl (xe2x80x94C6H4N3), benzotriazolylcarbonyloxy (xe2x80x94OC(xe2x95x90O)C6H4N3), benzotriazolyloxy (xe2x80x94Oxe2x80x94C6H4N3), benzotriazolylamino (xe2x80x94NHxe2x80x94C6H4N3), xe2x80x94CONHOH, xe2x80x94COOH, xe2x80x94OH, xe2x80x94SH, xe2x80x94COSH, xe2x80x94COSeH, xe2x80x94C5H4N, xe2x80x94SeH, xe2x80x94SO3H, xe2x80x94NC, xe2x80x94SiCl(CH3)2, xe2x80x94SiCl2CH3, amino, and phosphinyl;
and n is 1, 2, or 3 provided that n=1 when Z is xe2x80x94SiCl(CH3)2 or xe2x80x94SiCl2CH3; and wherein the organic semiconductor layer comprises a semiconductor of the formula:
wherein each R group is independently selected from electron-donating groups, halogen atoms, hydrogen atoms, and combinations thereof, provided that not all R groups are hydrogen; m is 1, 2, 3, or 4; each R9 and R10 is independently H or any R group; and any combination of two adjacent R groups may together form a five or six carbon cyclic aliphatic or aromatic group; provided that neither R2 with R3 nor R6 with R7 form part of a six-member aromatic ring; and provided that when m is 1 neither R9 nor R10 form part of a six-member aromatic ring.
As used herein, xe2x80x9celectron-donating groupxe2x80x9d means C1-C24 alkyl, alkoxy, thioalkoxy, or combinations thereof, which may be substituted or unsubstituted and xe2x80x9csubstitutedxe2x80x9d means, for a chemical species, substituted by a group that does not interfere with the desired product or process, e.g., substituents can be alkyl, alkoxy, aryl, phenyl, halo (F, Cl, Br, I), etc.
Various thin film transistor construction options are possible. For example, the source and drain electrodes may be adjacent to the gate dielectric with the organic semiconductor layer over the source and drain electrodes, or the organic semiconductor layer may be interposed between the source and drain electrodes and the gate dielectric.
In another aspect, the present invention provides a method of making a thin film transistor comprising the steps of providing a substrate, providing a gate electrode material on the substrate, providing a gate dielectric on the gate electrode material, providing a self-assembled monolayer (SAM) adjacent to the gate dielectric, the monolayer being a product of a reaction between the gate dielectric and a precursor to the self-assembled monolayer, applying an organic semiconductor layer on the monolayer, and providing a source electrode and a drain electrode contiguous to the organic semiconductor layer. The precursor is as described above with the organic thin film transistor article. The organic semiconductor layer also is as described above with the organic thin film transistor article. An integrated circuit comprising organic thin film transistor articles is also provided.
It is an advantage of the present invention to provide organic thin film transistors with one or more improvements over known devices that lack the features of the present invention. With the invention, improvements in properties such as threshold voltage, subthreshold slope, on/off ratio, and charge-carrier mobility can be achieved. The improvements in device performance provided by the present invention enable the production of more complicated circuits having faster switching speeds and simpler processing conditions. This invention also enables the production of larger circuit elements having comparable performance to devices with very small features. Devices with larger feature sizes can be less expensive as they do not require expensive precision patterning processes.
Other features and advantages of the invention will be apparent from the following detailed description of the invention and the claims. The above summary of principles of the disclosure is not intended to describe each illustrated embodiment or every implementation of the present disclosure. The following detailed description more particularly exemplifies certain preferred embodiments utilizing the principles disclosed herein.
Generally, a thin film transistor includes a gate electrode, a gate dielectric on the gate electrode, a source electrode and a drain electrode adjacent to the gate dielectric, and a semiconductor layer adjacent to the gate dielectric and adjacent to the source and drain electrodes. More specifically, an organic thin film transistor (OTFT) has an organic semiconductor layer. Such OTFTs are known in the art as shown, for example, in copending application U.S. Ser. No. 09/947,845, Attorney Docket No. 56999US002, filed on Sep. 6, 2001, now U.S. Pat. No. 6,433,359, which is herein incorporated by reference.
The organic thin film transistor of the present invention further includes a self-assembled monolayer (SAM) interposed between the gate dielectric and the organic semiconductor layer, and wherein the organic semiconductor comprises a substituted acene.
Substrate
A substrate can be used to support the OTFT, e.g., during manufacturing, testing, storage, use, or any combination thereof. The gate electrode and/or gate dielectric may provide sufficient support for the intended use of the resultant OTFT such that another substrate is not required. For example, doped silicon can function as the gate electrode and support the OTFT. In another example, one substrate may be selected for testing or screening various embodiments while another substrate is selected for commercial embodiments. In another embodiment, a support may be detachably adhered or mechanically affixed to a substrate, such as when the support is desired for a temporary purpose. For example, a flexible polymeric substrate may be adhered to a rigid glass support, which support could be removed. In some embodiments, the substrate does not provide any necessary electrical function for the OTFT. This type of substrate is termed a xe2x80x9cnon-participating substratexe2x80x9d in this document.
Useful substrate materials can include organic and/or inorganic materials. For example, the substrate may comprise inorganic glasses, ceramic foils, polymeric materials, filled polymeric materials, coated metallic foils, acrylics, epoxies, polyamides, polycarbonates, polyimides, polyketones, poly(oxy-1,4-phenyleneoxy-1,4-phenylenecarbonyl-1,4-phenylene)(sometimes referred to as poly(ether ether ketone) or PEEK), polynorbornenes, polyphenyleneoxides, poly(ethylene naphthalenedicarboxylate) (PEN), poly(ethylene terephthalate) (PET), poly(phenylene sulfide) (PPS), and fiber-reinforced plastics (FRP), and combinations thereof.
A flexible substrate is used in some embodiments of the present invention. This allows for roll processing, which may be continuous, providing economy of scale and economy of manufacturing over flat and/or rigid substrates. The flexible substrate chosen preferably is capable of wrapping around the circumference of a cylinder of less than about 50 cm diameter without distorting or breaking. The substrate chosen more preferably is capable of wrapping around the circumference of a cylinder of less than about 25 cm diameter without distorting or breaking the substrate. In some embodiments, the substrate chosen most preferably is capable of wrapping around the circumference of a cylinder of less than about 10 cm diameter, or even about 5 cm diameter, without distorting or breaking the substrate. The force used to wrap the flexible substrate of the invention around a particular cylinder typically is low, such as by unassisted hand, i.e., without the aid of levers, machines, hydraulics, and the like. The flexible substrate may be rolled upon itself.
Gate Electrode
The gate electrode can be any useful conductive material. For example, the gate electrode may comprise doped silicon, or a metal, such as aluminum, chromium, copper, gold, silver, nickel, palladium, platinum, tantalum, and titanium. Conductive polymers also can be used, for example polyaniline, poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS). In addition, alloys, combinations, and multilayers of these materials may be useful.
In some embodiments of the invention, the same material can provide the gate electrode function and also provide the support function of the substrate. For example, doped silicon can function as the gate electrode and support the OTFT.
Gate Dielectric
The gate dielectric is provided on the gate electrode, for example, through a deposition process. This gate dielectric electrically insulates the gate electrode under the operating conditions of the OTFT device from the balance of the device. Thus, the gate dielectric comprises an electrically insulating material. The gate dielectric should have a dielectric constant above about 2, more preferably above about 5. The dielectric constant of the gate dielectric also can be very high, for example, 80 to 100 or even higher. Useful materials for the gate dielectric may comprise, for example, an organic or inorganic electrically insulating material, or combinations thereof.
The gate dielectric may comprise a polymeric material, such as polyvinylidenefluoride (PVDF), cyanocelluloses, polyimides, epoxies, etc. In some embodiments, an inorganic capping layer comprises the outer layer of an otherwise polymeric gate dielectric.
Some specific examples of inorganic materials useful for the gate dielectric include strontiates, tantalates, titanates, zirconates, aluminum oxides, silicon oxides, tantalum oxides, titanium oxides, silicon nitrides, barium titanate, barium strontium titanate, barium zirconate titanate, zinc selenide, and zinc sulfide. In addition, alloys, combinations, and multilayers of these can be used for the gate dielectric. Of these materials, aluminum oxides, silicon oxides, silicon nitrides, and zinc selenide are preferred.
The gate dielectric can be deposited in the OTFT as a separate layer, or formed on the gate such as by oxidizing, including anodizing, the gate material to form the gate dielectric.
Source and Drain Electrodes
The source electrode and drain electrode are separated from the gate electrode by the gate dielectric, while the organic semiconductor layer can be over or under the source electrode and drain electrode. The source and drain electrodes can be any useful conductive material. Useful materials include those described above for the gate electrode as well as barium and calcium.
The thin film electrodes (e.g., gate electrode, source electrode, and drain electrode) can be provided by any useful means such as physical vapor deposition (e.g., thermal evaporation, sputtering) or ink jet printing. The patterning of these electrodes can be accomplished by known methods such as shadow masking, additive photolithography, subtractive photolithography, printing, microcontact printing, and pattern coating.
Organic Semiconductors
In an embodiment of the present invention, the organic semiconductor layer comprises a material selected from an acene, substituted with at least one electron-donating group, halogen atom, or a combination thereof, or a benzo-annellated acene or polybenzo-annellated acene, which optionally is substituted with at least one electron-donating group, halogen atom, or a combination thereof. The electron-donating group is selected from an alkyl, alkoxy, or thioalkoxy group having from 1 to 24 carbon atoms.
In another embodiment of the present invention, the organic semiconductor layer comprises a semiconductor of the formula:
wherein each R group is independently selected from electron-donating groups, halogen atoms, hydrogen atoms, and combinations thereof, provided that not all R groups are hydrogen; m is 1, 2, 3, or 4; each R9 and R10 is independently H or any R group; and any combination of two adjacent R groups may together form a five or six carbon cyclic aliphatic or aromatic group; provided that neither R2 with R3 nor R6 with R7 form part of a six-member aromatic ring; and provided that when m is 1 neither R9 nor R10 form part of a six-member aromatic ring.
Alkyl- or polyalkyl-substituted acenes are preferred classes of organic semiconductor materials that are useful in this invention. As used herein, xe2x80x9cpolyalkylxe2x80x9d, and xe2x80x9cpolyalkoxyxe2x80x9d, and xe2x80x9cpolybenzoxe2x80x9d mean more than one alkyl, alkoxy, or benzo group.
Non-limiting examples of benzo-annellated and polybenzo-annellated acenes include 1,2-benzanthracene (benz[a]anthracene or tetraphene), 1,2:3,4-dibenzanthracene (dibenz[a,c]anthracene), 1,2:5,6-dibenzanthracene (dibenz[a,h]anthracene), 1,2:7,8-dibenzanthracene (dibenz[a,j]anthracene), 1,2:3,4:5,6-tribenzanthracene (tribenz[a,c,h]anthracene), 1,2:3,4:5,6:7,8-tetrabenzanthracene (tetrabenz[a,c,h,j]anthracene, 1,2-benzotetracene (benzo[a]naphthacene), 1,2:3,4-dibenzotetracene (dibenzo[a,c]naphthacene), 1,2:7,8-dibenzotetracene (dibenzo[a,j]naphthacene), 1,2:9,10-dibenzotetracene (dibenzo[a,l]naphthacene), 1,2:3,4:7,8-tribenzotetracene (tribenzo[a,c,j]naphthacene), 1,2:3,4:7,8:9,10-tetrabenzotetracene (tetrabenzo[a,c,j,l]naphthacene), 1,2-benzopentacene (benzo[a]pentacene), 1,2:3,4-dibenzopentacene (dibenzo[a,c]pentacene), 1,2:8,9-dibenzopentacene (dibenzo [a,l]pentacene), 1,2:10,11-dibenzopentacene (dibenzo[a,n]pentacene), 1,2:3,4:8,9:10,11-tetrabenzopentacene (tetrabenzo[a,c,l,n]pentacene, 1,2-benzohexacene (benzo[a]hexacene), and substituted derivatives thereof. Further examples include benzoacenes with the benzo group attached to two rings of the acene, such as dibenzo[de,qr]tetracene (dibenzo[de,qr]naphthacene or naphtho[2,3-e]pyrene), zethrene (dibenzo[de,mn]naphthacene), dibenzo[de,st]pentacene, and dibenzo[de,uv]pentacene. In the preceding list, the common name is given followed by alternative names or Chemical Abstracts Service (CAS) names in parentheses.
Such acenes may be substituted, such as with at least one alkyl group. Preferred but non-limiting examples of alkyl groups are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, n-pentyl, n-hexyl, n-heptyl, 2-methylhexyl, 2-ethylhexyl, n-octyl, n-nonyl, n-decyl, n-dodecyl, n-octadecyl, and 3,5,5-trimethylhexyl.
Examples of alkyl-substituted acenes useful in the present invention include but are not limited to the following: 1-methylanthracene, 2-methylanthracene, 1,2-dimethylanthracene, 2,3-dimethylanthracene, 2,3,6,7-tetramethylanthracene, 1,2,3,4-tetramethylanthracene, 2-ethylanthracene, 2,6-diethylanthracene, 2-hexylanthracene, 2,6-dihexylanthracene, 1-methyltetracene, 2-methyltetracene, 2,3-dimethyltetracene, 2,8-dimethyltetracene, 2,3,9,10-tetramethylpentacene, 2-ethyltetracene, 2,8-diethylpentacene, 2,9-diethylpentacene, 2-hexyltetracene, 2-nonyltetracene, 1-methylpentacene, 2-methylpentacene, 2,3-dialkylpentacenes, 2,9-dialkylpentacenes, and 2,10-dialkylpentacenes (e.g., 2,3-dimethylpentacene, 2,9-dimethylpentacene, 2,10-dimethylpentacene), 2-ethylpentacene, 2,10-dialkoxypentacenes, 2,3,9,10-tetraalkylpentacenes, 1,4,8,11-tetraalkoxypentacenes, and 1,2,3,4,8,9,10,11-octaalkylpentacene, wherein the alkyl or alkoxy group in each of the formulas above has from 1 to 24 carbons. Preferred dialkyl acenes include 2,6-dialkylanthracene, 2,8-dialkyltetracene, and 2,9-dialkylpentacene.
Alkyl-substituted acenes can be prepared by any known method. For example, various methyl-substituted anthracenes are taught in Table XXIV in E. Clar, Polycyclic Hydrocarbons, Volume 1, Academic Press (London and New York) and Springer-Verlag (Berlin, Gottingen and Heidelberg), 1964, pages 298-299. Other alkylanthracenes can be prepared by similar methods as described in Table XXIV of the same reference, which is herein incorporated by reference.
Substituted tetracenes also can be prepared by any known method, including for example, the following sequence of reactions: 1) the condensation of naphthalene-2,3-dicarboxylic anhydride and benzene derivatives, 2) dehydration to form the corresponding tetracene-5,12-quinone, 3) and reduction of the quinone to give the corresponding tetracene derivative. Such methods are taught, e.g., in Waldmann, H. and Mathiowetz, H., Ber. dtsch. Chem. Ges. 64, 1713 (1931), Weizmann, C., Haskelberg, L. and Berlin, T., J. Chem. Soc. 398 (1939); Waldemann, H. and Plak, G., J. prakt. Chem. (2) 150, 113, 121 (1938), which are herein incorporated by reference. Other examples of synthesis of alkyl homologues of tetracene include: 2-methyltetracene (Coulson, E. A., J. Chem. Soc. 1406 (1934)), 5-methyltetracene (Clar, E. and Wright, J. W., Nature, Lond. 63, 921 (1949)), 2-isopropyltetracene (Cook, J. W., J. Chem. Soc. 1412 (1934)), 1,6-dimethyltetracene (Fieser, L. F. and Hershberg, E. B. J. Amer. Chem. Soc. 62, 49 (1940)), 2,8-dimethyltetracene (Fieser, L. F. and Hershberg, E. B. J. Amer. Chem. Soc. 62, 49 (1940) and Coulson, E. A., J. Chem. Soc. 1406 (1934)), 2,9-dimethyltetracene (Coulson, E. A., J. Chem. Soc. 1406 (1934)), and 5,12-dimethyltetracene (Wolf, J., J. Chem. Soc. 75, 2673 (1953)), which are herein incorporated by reference.
Substituted pentacene compounds that are useful as organic semiconductors in the present invention include compounds comprising at least one substituent selected from the group consisting of electron-donating substituents (e.g., alkyl, alkoxy, thioalkoxy), halogen substituents, and combinations thereof. Useful substituted pentacenes include but are not limited to 2,9-dialkylpentacenes and 2,10-dialkylpentacenes, 2,10-dialkoxypentacenes, 2,3,9,10-tetraalkylpentacenes, and 1,4,8,11-tetraalkoxypentacenes, wherein each alkyl or alkoxy group in the preceding formulas has from 1 to 24 carbons. Such substituted pentacenes are taught in copending applications U.S. Ser. No. 09/966,954, Attorney Docket No. 57087US002, and U.S. Ser. No. 09/966,961, Attorney Docket No. 57088US002, both filed on Sep. 27, 2001, both now abandoned, which are herein incorporated by reference.
Further details of benzo-annellated and polybenzo-annellated acenes can be found in the art, for example, in NIST Special Publication 922 xe2x80x9cPolycyclic Aromatic Hydrocarbon Structure Indexxe2x80x9d, U.S. Govt. Printing Office, by Sander and Wise (1997).
As used herein, the numbering sequence that is used for pentacene is exemplified with the structure shown below.
The location of a substituent on such a compound is commonly specified by reference to the number of the carbon atom to which the substituent is bonded. There is one hydrogen atom bonded to each numbered carbon atom if no substituent is indicated.
Substituted pentacene semiconductors useful in the present invention can be prepared by a process comprising the steps of (1) combining at least one substituted benzene (more specifically, at least one mono-, di-, tri-, or tetrasubstituted benzene having at least two adjacent ring carbon atoms that are bonded to hydrogen) and pyromellitic dianhydride (or a derivative thereof), in the presence of a Lewis acid (for example, AlCl3), to form substituted bis(benzoyl)phthalic acids via a Friedel-Crafts reaction; (2) reducing the substituted bis(benzoyl)phthalic acids to give the corresponding substituted bis(benzyl)phthalic acids; (3) cyclizing the substituted bis(benzyl)phthalic acids to give the corresponding substituted pentacenediones; (4) reducing the substituted pentacenediones to give the corresponding substituted pentacenediols; and (5) dehydrating the substituted pentacenediols to form the corresponding substituted pentacenes. As used herein, the term xe2x80x9cphthalic acidxe2x80x9d refers to terephthalic acid (1,4-benzenedicarboxylic acid), isophthalic acid (1,3-benzenedicarboxylic acid), and combinations thereof.
The step of combining at least one substituted benzene with pyromellitic dianhydride (benzene-1,2,4,5-tetracarboxylic acid dianhydride) or a derivative thereof (for example, dimethyl 2,5-bis(chlorocarbonyl)terephthalate) to form substituted bis(benzoyl)phthalic acids can be represented by the following general scheme:
wherein each R (that is, each of the groups R1 through R8) is independently selected from the group consisting of electron-donating groups, halogen atoms, hydrogen atoms, and combinations thereof. Preferably, each R is independently selected from alkyl groups, alkoxy groups, thioalkoxy groups, halogen atoms, hydrogen atoms, and combinations thereof. More preferably, each R is independently selected from alkyl groups, alkoxy groups, hydrogen atoms, and combinations thereof. Even more preferably, each R is independently an alkyl group or a hydrogen atom. Most preferably, each R is independently methyl, n-hexyl, n-nonyl, n-dodecyl, n-octadecyl, sec-butyl, 3,5,5-trimethylhexyl, 2-ethylhexyl, or a hydrogen atom. Preferably, R2 and R6 (or R2 and R7) are moieties other than hydrogen while hydrogen comprises the balance of the R groups. In addition, R2 and R6 preferably are moieties other than hydrogen for the substituted bis(benzoyl)terephthalic acid and R2 and R7 preferably are moieties other than hydrogen for the substituted bis(benzoyl)isophthalic acid.
Reactions of this type (electrophilic aromatic substitution reactions) are known and have been described, for example, by Diesbach and Schmidt in Helv. Chim. Acta 7, 648 (1924); by Mills and Mills in J. Chem. Soc. 101, 2200 (1912); by Philippi in Monatshefte fuer Chemie 32, 634 (1911); by Philippi and Seka in Monatshefte fuer Chemie 43, 615 (1922); by Philippi and Auslaender in Monatshefte fuer Chemie 42, 1 (1921); and by Machek in Monatshefte fuer Chemie 56, 130 (1930). Preferably, the reaction is carried out in the presence of an inert solvent and an amine base in order to keep the reaction mixture fluid and to decrease the amount of rearrangement of the substituents on the aromatic ring during the reaction. Examples of useful inert solvents include 1,2-dichloroethane, dichlorobenzene, dichloromethane, carbon disulfide, nitrobenzene, and nitromethane. Examples of useful amine bases include tertiary amines such as triethylamine, diisopropylethylamine, and 1,4-diazabicyclo[2.2.2]octane (DABCO). If desired, the reaction mixture can be agitated and/or heated.
Representative examples of substituted benzenes that can be used to prepare the substituted bis(benzoyl)phthalic acids include mono- and dialkoxybenzenes; mono- and dithioalkoxybenzenes; mono- and dihalobenzenes; and mono-, di-, tri-, and tetraalkylbenzenes (for example, toluene, hexylbenzene, nonylbenzene, dodecylbenzene, sec-butylbenzene, p-xylene, 1,2,3,4-tetrahydronaphthalene, 3,5,5-trimethylhexylbenzene, 2-ethylhexylbenzene, and 1,2,3,4-tetramethylbenzene).
Alternatively, the substituted bis(benzoyl)phthalic acids can be prepared by reaction of pyromellitic dianhydride or a derivative thereof with a substituted aromatic organometallic reagent (for example, an aryl magnesium halide or an aryl lithium compound).
The resulting substituted bis(benzoyl)phthalic acids can be reduced to the corresponding substituted bis(benzyl)phthalic acids via reduction methods known in the art. For example, the reduction can be accomplished by using either zinc and aqueous ammonium hydroxide (preferably, with agitation) or catalytic hydrogenation with, for example, palladium or platinum on carbon at, for example, about 2 to 3 atmospheres (preferably, by catalytic hydrogenation; more preferably, by catalytic hydrogenation with palladium on carbon) as shown, for example, below:
wherein each R (that is, each of the groups R1 through R8) is as defined above for Scheme A. If desired, the substituted bis(benzoyl)terephthalic acids can be separated from the substituted bis(benzoyl)isophthalic acids by methods commonly used in the art (for example, by recrystallization, trituration, or chromatography) before the reduction reaction is carried out (or, alternatively, the resulting substituted bis(benzyl)phthalic acid isomers can be separated thereafter).
The cyclization step of the process can be accomplished via intramolecular Friedel-Crafts cyclization of the substituted bis(benzyl)phthalic acids to form the corresponding substituted pentacenediones (the substituted 7,14-dihydropentacene-5,12-diones and the substituted pentacene-5,7(12H,14H)-diones; hereinafter, the xe2x80x9c5,12-dionesxe2x80x9d and the xe2x80x9c5,7-dionesxe2x80x9d).
The use of acid catalyzed Friedel-Crafts cyclization to form cyclic ketones is well known in the literature and has been described, for example, by Premasagar et al. in J. Org. Chem., 46(14), 2974 (1981); by Allen et al. in Tetrahedron, 33(16), 2083 (1977); and by Hulin et al. in J. Org. Chem., 49, 207 (1984). These reactions can generally be carried out at about 0xc2x0 C. to 100xc2x0 C. in the presence of a strong acid such as concentrated sulfuric acid, fuming sulfuric acid, polyphosphoric acid or anhydrous hydrofluoric acid. For example, unsubstituted bis(benzoyl)phthalic acid will form the corresponding tetrone when heated to 100xc2x0 C. with concentrated sulfuric acid for several hours.
However, both substituted bis(benzoyl)phthalic acids and substituted bis(benzyl)phthalic acids are usually unreactive under these conditions. It appears that in general the intramolecular Friedel-Crafts cyclization of these substituted compounds cannot be readily accomplished with the strong acids that are typically used for this type of reaction. It has been discovered, however, that Friedel-Crafts cyclization of substituted bis(benzyl)phthalic acids to form the corresponding substituted pentacenediones can be accomplished using an acid composition comprising trifluoromethanesulfonic acid as shown, for example, below:
wherein each R (that is, each of the groups R1 through R8) is defined as above for Formula II, with the clarification that preferably R2 and R6 are moieties other than hydrogen for the substituted 5,12-dione (and that R2 and R7 are moieties other than hydrogen for the substituted 5,7-dione).
The cyclization reaction can be carried out at room temperature or, optionally, at elevated temperatures (for example, a temperature in the range of about 20xc2x0 C. to 60xc2x0 C.) and, preferably, with agitation of the reaction mixture. The trifluoromethanesulfonic acid can be used alone or in combination with, for example, trifluoroacetic acid, or a perfluoroalkanesulfonic acid of higher molecular weight than trifluoromethanesulfonic acid, or a neutral solvent that will not react with trifluoromethanesulfonic acid (for example, a hydrocarbon solvent, a chlorinated solvent such as methylene chloride or a fluorinated solvent) or a Lewis acid (for example, antimony pentafluoride).
The resulting substituted pentacenediones can be reduced and dehydrated to give the corresponding substituted pentacenes. Good yields can usually be obtained by, for example, a sodium borohydride reduction procedure, as shown, for example, below:
wherein each R (that is, each of the groups R1 through R8) is defined as above for Reaction Scheme C.
Treatment of the diones with sodium borohydride in solvent, such as alcohol(s) or ether(s) (preferably, diglyme) or a combination thereof, preferably followed by addition of methanol and then treatment with additional sodium borohydride gives the corresponding substituted diols. The diols can then be dehydrated to substituted pentacenes by treatment with an acid (for example, hydrochloric acid), preferably with application of heat (for example, heating to about 50xc2x0 C. to 60xc2x0 C.) and agitation. Suitable acids include, for example, acetic acid, phosphoric acid, hydrochloric acid, sulfuric acid, hydroiodic acid, hydrobromic acid, trifluoroacetic acid, and trifluoromethanesulfonic acid. Optionally, the diols can first be treated with a weak acid, such as acetic acid, followed by treatment with a stronger acid, such as hydrochloric acid.
Benzoacenes can be prepared by any known method, for example, as described in E. Clar, Polycyclic Hydrocarbons, Vol. 1, Academic Press (London and New York) and Springer-Verlag (Berlin, Gottingen and Heidelberg), 1964, which depicts 1,2-benzopentacene and 1,2:3,4-dibenzopentacene at pages 436-446.
If desired, the resulting substituted acenes can be purified one or more times by standard methods such as recrystallization, sublimation, trituration, continuous extraction, chromatography, or a combination thereof. Purification can be accomplished by sublimation, for example, using a 3-zone furnace (e.g., a Thermolyne 79500 tube furnace, available from Barnstead Thermolyne, Dubuque, Iowa) at reduced pressure under a constant flow of nitrogen gas.
The organic semiconductor layer can be provided in the OTFT of the invention by any useful means, such as for example, vapor deposition, spin coating, and printing techniques including transfer printing.
Self-Assembled Monolayer
The self-assembled monolayer (SAM) is interposed between the gate dielectric and the organic semiconductor layer. The monolayer is a product of a reaction between the gate dielectric and a precursor to the self-assembled monolayer.
Self-assembled monolayer precursors provide molecules that form a self-assembled layer, typically a monolayer, on the target surface. Self-assembled thin layers are often prepared by coating a substrate of interest in a dilute solution of the self-assembling precursor or by exposure to a vapor phase containing the precursor, and allowing layer formation to proceed. The precursor molecules form a molecular layer on the substrate with the reactive groups attached to the dielectric surface. Once formed, the layer does not redissolve in the solvent from which it was deposited.
Generally, materials that form crosslinks independently of monolayer formation that may be in competition with the adsorption or bonding reaction to the gate dielectric, such as trifunctional silanes, are not desired for the monolayer precursor of the present invention. However, materials that have functional groups effective to bond to the gate dielectric and have other groups that may form crosslinks after formation of the SAM can be used.
The monolayer precursor comprises a composition having the formula:
Xxe2x80x94Yxe2x80x94Zn,
wherein X is H or CH3;
Y is a linear or branched C5-C50 aliphatic or cyclic aliphatic connecting group, or a linear or branched C8-C50 group comprising an aromatic group and a C3-C44 aliphatic or cyclic aliphatic connecting group;
Z is selected from xe2x80x94PO3H2, xe2x80x94OPO3H2, benzotriazolyl (xe2x80x94C6H4N3), benzotriazolylcarbonyloxy (xe2x80x94OC(xe2x95x90O)C6H4N3), benzotriazolyloxy (xe2x80x94Oxe2x80x94C6H4N3), benzotriazolylamino (xe2x80x94NHxe2x80x94C6H4N3), xe2x80x94CONHOH, xe2x80x94COOH, xe2x80x94OH, xe2x80x94SH, xe2x80x94COSH, xe2x80x94COSeH, xe2x80x94C5H4N, xe2x80x94SeH, xe2x80x94SO3H, isonitrile (xe2x80x94NC), chlorodimethylsilyl (xe2x80x94SiCl(CH3)2), dichloromethylsilyl (xe2x80x94SiCl2CH3), amino, and phosphinyl;
and n is 1, 2, or 3 provided that n=1 when Z is xe2x80x94SiCl(CH3)2 or xe2x80x94SiCl2CH3.
Herein, the reaction between any gate dielectric and a functional group within the self-assembled monolayer precursor is preferably a bonding interaction (e.g., covalent or ionic). Herein, a self-assembled monolayer refers to a mono-molecular layer on the order of about 5 Angstroms (xc3x85) to about 30 xc3x85 thick.
In preferred embodiments, Y can be a saturated aliphatic group, an unsaturated aliphatic group, a saturated cyclic aliphatic group, and an unsaturated cyclic aliphatic group, or a combination thereof, each of which may be linear or branched.
The monolayer precursor may comprise a linear or branched phosphonoalkane having from 5 to 50 carbon atoms, more preferably 6 to 24. The monolayer precursor may comprise a composition of the formula:
xe2x80x83CH3xe2x80x94(CH2)mxe2x80x94PO3H2,
wherein m is an integer from 4 to 21.
Particular examples for the monolayer precursor include 1-phosphonooctane, 1-phosphonohexane, 1-phosphonohexadecane, and 1-phosphono-3,7,11,15-tetramethylhexadecane.
One member of a class of branched hydrocarbon monolayer precursors useful in the practice of the present invention is 1-phosphono-3,7,11,15-tetramethylhexadecane. Other members of this class include 1-phosphono-2-ethylhexane, 1-phosphono-2,4,4-trimethylpentane, and 1-phosphono-3,5,5-trimethylhexane. The 1-phosphono-3,7,11,15-tetramethylhexadecane can be prepared from a commercially available allylic alcohol precursor by reduction of the alkene double bond, conversion of the alcohol to the corresponding bromide, and then conversion of the bromide to the corresponding phosphonic acid. More specifically, 1-phosphono-3,7,11,15-tetramethylhexadecane can be obtained by reducing 3,7,11,15-tetramethyl-2-hexadecen-1-ol to 3,7,11,15-tetramethyl-1-hexadecanol, converting the 3,7,11,15-tetramethyl-1-hexadecanol to 1-bromo-3,7,11,15-tetramethylhexadecane, and then converting the 1-bromo-3,7,11,15-tetramethylhexadecane to 1-phosphono-3,7,11,15-tetramethylhexadecane. These synthetic transformations are accomplished using materials and methods familiar to those skilled in the art. Starting materials other than 3,7,11,15-tetramethyl-2-hexadecen-1-ol and individual reaction sequences other than that described above may also be used to synthesize 1-phosphono-3,7,11,15-tetramethylhexadecane, as well as other members of this class of branched hydrocarbon monolayer precursors, and the specifically exemplified monolayer precursor and method of preparation should not be construed as unduly limiting.
The self-assembled monolayer precursor is provided on the gate dielectric by any known method. For example, the precursor can be provided through a process such as spray coating, spinning, dip coating, gravure coating, microcontact printing, ink jet printing, stamping, transfer printing, and vapor deposition. The self-assembled monolayer precursor is allowed to interact with the gate dielectric surface. The interaction or reaction may be instantaneous or may require time, in which case increasing the temperature can reduce the necessary time. When a solution of the self-assembled monolayer precursor is provided on the gate dielectric layer, the solvent is removed by a method compatible with the materials involved, for example by heating. Any excess monolayer precursor is typically rinsed away before deposition of the organic semiconductor. In a preferred embodiment, the SAM is provided by the steps consisting essentially of coating the precursor, heating, and rinsing without further processing.
In one embodiment, the source and drain electrodes are provided adjacent to the gate dielectric before providing the monolayer precursor. Then, the monolayer precursor is provided. After the self-assembled monolayer is complete, the organic semiconductor layer is provided over the source and drain electrodes and over the self-assembled monolayer adjacent to the gate dielectric.
The organic thin film transistor (OTFT) of the present invention has one or more advantages over known organic thin film transistors. These advantages are apparent, for example, in charge-carrier mobility. The present invention provides OTFTs having a charge-carrier mobility better than a comparison OTFT not made according to the present invention and thus lacking the inventive self-assembled monolayer, but otherwise similar in every construction feature. The OTFT of the invention preferably has a charge-carrier mobility of at least about 25% better, more preferably at least about 50% better, and in some embodiments at least about 100% better, than the charge-carrier mobility of a comparison OTFT similar in every respect but lacking the SAM of the present invention. Such improvements in charge-carrier mobility are provided while maintaining other OTFT properties within desirable ranges. For example, the above-described improvements are obtained while providing a threshold voltage between about 25 and xe2x88x9225 V, a subthreshold slope below about 10 V/decade (absolute value), and an on/off ratio of at least about 104.
More specifically, in an embodiment comprising a substituted pentacene as the organic semiconductor, the invention provides an OTFT with a charge-carrier mobility at least about 0.2 cm2/Vs, more preferably at least 0.5 cm2/Vs, and even more preferably at least about 1.0 cm2/Vs. In some embodiments of the present invention, the charge-carrier mobility is above 2.0 cm2/Vs.
One embodiment of the present invention provides a p-type semiconductor OTFT having a threshold voltage of between about xe2x88x9225 and 25 V, preferably a threshold voltage of between about 0 and xe2x88x9210 V, more preferably between about 0 and xe2x88x925 V.
The invention provides an OTFT with a subthreshold slope below about 10 V/decade (absolute value), preferably a subthreshold slope below about 5 V/decade (absolute value), more preferably below about 2 V/decade (absolute value). The invention provides an OTFT with an on/off ratio of at least about 104, preferably at least about 105, more preferably at least about 5xc3x97105, and even more preferably at least about 106.
Various combinations of these properties are possible. For example, in one embodiment of the invention, the p-type semiconductor OTFT has a charge-carrier mobility of at least about 1 cm2/Vs, a negative threshold voltage, a subthreshold slope below about 5 V/decade, and an on/off ratio at least about 105.
Methods of Making an OTFT
The present invention also provides a method of making a thin film transistor comprising the steps of: (a) providing a substrate; (b) providing a gate electrode material on the substrate; (c) providing a gate dielectric on the gate electrode material; (d) providing a self-assembled monolayer (SAM) adjacent to the gate dielectric, the monolayer being a product of a reaction between the gate dielectric and a precursor to the self-assembled monolayer, the precursor comprising a composition having the formula Xxe2x80x94Yxe2x80x94Zn, as described above; (e) applying an organic semiconductor layer as described above on the monolayer; and (f) providing a source electrode and a drain electrode contiguous to the organic semiconductor layer.
The organic semiconductor layer can be provided over or under the source and drain electrodes, as described above in reference to the thin film transistor article. The present invention also provides an integrated circuit comprising a plurality of OTFTs made by the process described above.
The present invention further provides a method of making an integrated circuit comprising providing a plurality of OTFTs as described above. Thus, the present invention is embodied in an article that comprises one or more of the OTFTs described. Such articles include, for example, radio-frequency identification tags, backplanes for active matrix displays, smart cards, memory devices, and the like. In devices containing the OTFTs of the present invention, such OTFTs are operatively connected by means known in the art.
The entire process of making the thin film transistor or integrated circuit of the present invention can be carried out below a maximum substrate temperature of about 450xc2x0 C., preferably below about 250xc2x0 C., more preferably below about 150xc2x0 C., and even more preferably below about 70xc2x0 C., or even at temperatures around room temperature (about 25xc2x0 C.). The temperature selection generally depends on the substrate and processing parameters known in the art, once one is armed with the knowledge of the present invention contained herein. These temperatures are well below traditional integrated circuit and semiconductor processing temperatures, which enables the use of any of a variety of relatively inexpensive substrates, such as flexible polymeric substrates. Thus, the invention enables production of relatively inexpensive integrated circuits containing organic thin film transistors with significantly improved performance.

Surface modified organic thin film transistors