A projection 24 is integrally formed at a front surface 22b of a light shielding plate 22. The light shielding plate 22 is interposed between a reflector 14 and a focusing lens 18. As the reflected light from the reflector 14 is deflected or reflected upward by the projection 24, light B1 for illuminating overhead-signs is made to propagate from the focusing lens 18. A front-end portion 24b of the projection 24 is has a curved surface such that the portion 24b and an upper inclined surface 24a of the projection 24 are smoothly connected to each other. The front-end portion 24b is prevented from being seen as dark relative to the surface 24a, which can be seen as being brightly lit by external light.

The invention relates to a projector-type headlamp for a vehicle, and more particularly to a low-beam headlamp.
In recent years, projector-type headlamps have come to be frequently adopted as headlamps for vehicles.
As shown in FIG. 1, a projector-type headlamp comprises a light source 102 disposed on an optical axis Ax of the headlamp which extends in the longitudinal direction of a vehicle, a reflector 104 for reflecting light from this light source 102 in a forward direction close to the optical axis Ax, and a focusing lens 106 disposed forwardly of the reflector 104.
Further, for using this projector-type headlamp as a low-beam headlamp, a light shielding plate 108 is provided between the focusing lens 106 and the reflector 104. The shielding plate 108 eliminates upwardly illuminating light by shielding part of the reflected light from the reflector 104. As a result, a luminous intensity distribution pattern P is formed for low beam light, showing a light-dark borderline CL, as shown in FIG. 2.
Since the upwardly illuminating light of such a projector-type headlamp is eliminated almost completely by the light shielding plate 108, an overhead sign installed above the road surface ahead of the vehicle cannot often be seen clearly.
Accordingly, an approach has been adopted, as shown in FIG. 3, to attach in the vicinity of an upper edge 108a an L-shaped plate 110 extending diagonally downward from a front surface 108b of the light shielding plate 108. Reflected light from the reflector 104 is deflected or reflected upward by an upper inclined surface 110a of the L-shaped plate 110. The reflected upward light propagates from the focusing lens 106 to illuminate overhead signs.
However, with the projector-type headlamp, a focal position of the focusing lens 106 is generally set at the upper edge 108a of the light shielding plate 108. The L-shaped plate 110 is attached to the front surface 108b of the light shielding plate 108 near the upper edge. Therefore, when the headlamp is viewed from a forward and slightly upper direction, the L-shaped plate 110 is seen enlarged by the lens action of the focusing lens 106, as shown in FIG. 4. External light causes the upper inclined surface 110a of the L-shaped plate 110 to be seen as brightly lit, while a front-end surface 110b of the L-shaped plate 110 remains dark. Hence, the visual appearance of the headlamp is degraded when exposed to external light.
The invention of this application has been devised in view of the above-described circumstances. The object is to provide a projector-type headlamp for a vehicle capable of obtaining light for illuminating overhead-signs without impairing the appearance of the headlamp.
In embodiments of the invention, the above object is attained by providing a structure for illuminating overhead signs.
An embodiment of the invention provides a projector-type headlamp for a vehicle comprising: a light source disposed on an optical axis of the headlamp extending in a longitudinal direction of a vehicle; a reflector for reflecting light from the light source in a forward direction close to the optical axis; a focusing lens disposed forwardly of the reflector; and a light shielding plate interposed between the focusing lens and the reflector so as to eliminate upward illuminating light by shielding part of the reflected light from the reflector, wherein a projection, which has an upper inclined surface extending diagonally downward in a forward direction and is adapted to deflect or reflect reflected light from the reflector upwardly at the upper inclined surface, is integrally formed at a front surface of the light shielding plate and at a position in a vicinity of a upper edge thereof, and a front-end portion of the projection is formed with a curved surface in such a manner as to be smoothly connected to the upper inclined surface.
The phrase xe2x80x9cdeflect or reflect . . . upwardlyxe2x80x9d means to deflect or reflect the reflected light from the reflector incident upon the upper inclined surface of the projection such that an angle of downward inclination of the reflected light becomes small, but does not necessarily mean to reflect the light upward.
As long as the aforementioned xe2x80x9cprojectionxe2x80x9d is capable of deflecting or reflecting the reflected light from the reflector in an upwardly direction and capable of allowing the light for illuminating overhead-signs to propagate from the focusing lens, an arrangement of the upper inclined surface, including its planar shape, size, the angle of downward inclination and the like, should not be limiting.
The projector-type headlamp in accordance with an embodiment of the invention is arranged such that a projection having an upper inclined surface extending diagonally downward in a forward direction is integrally formed at a front surface of the light shielding plate and in the vicinity of an upper edge of the plate, and the reflected light from the reflector is deflected or reflected upwardly from the upper inclined surface. Accordingly, light for illuminating overhead-signs can propagate from the focusing lens.
When the headlamp is observed from a forward and slightly upper direction, the projection is seen enlarged by the lens action of the focusing lens. However, when the headlamp is exposed to external light, since the front-end portion is formed with a curved surface and smoothly connected to the upper inclined surface, the front-end portion does not appear as dark relative to the upper inclined surface which is seen as brightly lit by the external light. The front-end portion can be seen as being lit with the brightness changing gradually. Moreover, since the projection is formed integrally with the light shielding plate, its front-end portion can be easily formed with a curved surface. Further, compared to the L-shaped plate attached to the light shielding plate in a conventional manner, the projection""s portion connected to the general portion of the light shielding plate can be seen as integrated and uniform in terms of its external appearance.
Therefore, it is possible to provide a projector-type headlamp for a vehicle capable of generating light for illuminating overhead-signs without impairing the appearance of the headlamp.
In addition, the portion of the light shielding plate in the vicinity of its upper edge is expected to reach a high temperature since the reflected light from the reflecting surface of the reflector is concentrated there. Also, the temperature of the projection is expected to become high. However, since the projection is formed integrally with the light shielding plate, the projection is unlikely to undergo thermal deformation, and the heat from the light shielding plate can be efficiently dissipated through the projection.
Further, although the angle of downward inclination of the upper inclined surface is not limiting as described above, if the angle of downward inclination is set to 25 to 35xc2x0, the illuminating light can propagate from the focusing lens at an angle of upward inclination suitable for illuminating the overhead signs. The reason for the 25xc2x0 lower-limit is that if it is set to less than 25xc2x0, the light from the upper inclined surface and a; through the focusing lens may be directed upward to a region above the overhead sign. On the other hand, the reason for the 35xc2x0 upper-limit is that if it is set to more 35xc2x0, the light from the upper inclined surface and through the focusing lens may be directed downward to a region below the overhead sign.
The aforementioned xe2x80x9cupper inclined surfacexe2x80x9d may be one whose rear-end portion extends up to the front surface of the light shielding plate or one whose rear-end portion extends halfway. Whichever case, the line of intersection between the upper inclined surface or its rearwardly extending surface and the front surface of the light shielding plate is preferably set at a position 0.5 to 3.0 mm below the upper edge of the light shielding plate. The reason for this is that if the distance is less than 0.5 mm, the intensity of light incident upon the upper inclined surface can become substantially high, and upwardly illuminating light may exceed a luminosity necessary for illuminating the overhead sign and may cause glare. On the other hand, if the distance exceeds 3.0 mm, the intensity of light incident upon the upper inclined surface can become insufficient. It can also be difficult to obtain a luminosity necessary for illuminating the overhead sign. Therefore, it is preferable to set the distance in the range of 0.5 to 3.0 mm.
Instead of using one projection, a plurality of projections can be juxtaposed transversely to obtain light suitable for illuminating overhead signs. Each projection""s arrangement, its size of the upper inclined surfaces, its downward angle or the like may be appropriately set.


An air filter restriction sensor assembly for use on an engine, such as a small gas engine provides a simple on/off system with remote indicating to notify the operator of the air restriction. More specifically, the air restriction in the air intake line of the engine creates a vacuum which pulls on a plunger mechanism until the mechanism contacts a switch, such as a membrane switch, and activates the switch. The switch can be electrically connected to an indicator device, such as a light-emitting diode, which is readily visible to the operator to notify the operator of the air restriction.

It is known that small gas engines are used on equipment and vehicles such as lawn mowers, lawn tractors, and the like. When used on lawn mowers, for example, the engines are exposed to the environment where they may be subject to debris, dirt, moisture, or other contaminants. To maintain the proper functioning of the gas engine, air filters are used to screen and filter the air that is taken in by the engine and more specifically the carburetor of the engine. In many applications, the air filter is concealed from view and therefore when dirt or debris is on the filter, thereby restricting the air flow, this condition is not readily apparent to the operator.
To overcome this problem, known engines sometimes include a sensor mechanism to detect if the dirt or debris on the air filter is restricting the air flow to the engine. As the air filter on the engine becomes dirty and the air flow becomes restricted, vacuum is increased in the air intake line of the engine downstream from the air filter. Conventionally, the vacuum created by the air restriction is detected by a spring-loaded sensor device, a micro-switch, or both, that show the operator the state of the air filter restriction. The springs or micro-switches, however, wear out over time, can give false readings from the engine vibration, or can be difficult to calibrate.
The present invention is directed at improving upon known air filter restriction sensor assemblies and in particular air filter restriction sensor assemblies for small gas engines.


An electronic mail processing device includes a magnetic disk with a control table. The device establishes a line between an originating terminal and a destination terminal designated by the originating terminal as a destination of electronic mail information and enters the destination into the control table provided on the magnetic disk as a wrong destination when the destination terminal performs no prescribed response operation to receive the electronic mail information. No electronic mail information is delivered to any of destinations entered into the control table. Thereby, once a destination is stored in the control table, a line is never connected to the destination terminal again, which prevents repeated wrong calls from being made to the same terminal.

1. Field of the Invention
The present invention relates to an electronic mail system which delivers various types of electronic mail information, such as facsimiles, voices, text, etc., transmitted over a communication network to their respective destination terminals.
2. Description of the Related Art
With the recent spread of information communication service, the demand for a system for automatic delivery of various types of information, such as images, voices, text (characters), etc., to remote locations is increasing. To meet the demand, an electronic mail system has come into use which permits free transmission and reception of such information among various types of terminals, such as facsimile equipment, personal computers or telephone sets, over a communication network such as a public communication network.
The electronic mail system has a facility for storing mail information sent from a terminal temporarily in a mail center and delivering the stored mail information to a destination terminal or terminals at time and in a way (for example, one-to-one individual communication, one-to-N broadcast communication) which are specified by a user.
FIG. 1 illustrates the system configuration of a prior electronic mail system.
A number of terminals 1a, 1b, . . . , such as telephone sets, facsimile equipment, etc., are connected to an electronic mail processing apparatus (hereinafter referred to as a mail apparatus) 3 installed in the mail center via a public telephone network or a private telephone network 2.
In general, the electronic mail system provides electronic mail service to subscribers which are assigned their respective identification numbers (subscriber's numbers, ID).
To send mail information to the mail apparatus 3, a user operates push buttons of a telephone in accordance with the following procedure:
(1) The user dials the telephone number of the mail center.
(2) The mail center prompts the user through voice guidance to enter his or her identification number.
(3) The user operates push buttons to enter his or her identification number.
(4) The mail center prompts the user through voice guidance to specify a mail service (individual communication, broadcast communication, etc.) that he or she requests.
(5) The user operates push buttons to specify his or her mail service.
(6) The mail center prompts the user through voice guidance to enter the destination of the mail information.
(7) The user operates buttons to enter the destination (in the case of broadcast communication all the destinations are entered).
(8) The mail center prompts the user to send a message.
(9) The user transmits the message through telephone or facsimile.
In order to send mail information using a mail system it is required, as described above, that user operates buttons on a telephone to enter his or her subscriber's identification number, the type of a mail service that he or she requests, the destination number and so on. These input operations are troublesome and time-consuming. In the case of the one-to-N broadcast communication in particular, the user has to enter destination numbers in succession. Thus, problems arise in that the operations are troublesome and time-consuming and the possibility of operational errors increases.
If a destination number is entered in error, the mail apparatus 3 will send received mail information to the wrong destination. Thus, problems will arise in that others may be troubled by misdelivery of mail information and the leakage of confidential information may be caused.
The following measures have been taken to prevent misdelivery of mail information caused by misentry of destination numbers. That is, subscribers (terminals) of destination are classified into groups (grouping of destinations) and destination information (telephone numbers and facsimile equipment numbers) of subscribers is entered for each of groups, thereby restricting delivery of mail information to subscribers which are not entered (subscribers entered in other groups).
However, the destination grouping method requires that all the destinations should be entered beforehand, which is time-consuming. In the case of broadcast delivery to subscribers in a combination different from that of destinations entered in a group, the destinations of the subscribers have to be entered into the mail apparatus again. Thus, the destination grouping method is not easy to use.

Electronic mail system for transmitting information via communication network


A method of manufacturing a developing roller includes two steps. First, a grinding wheel is moved along the length of a developing roller which has been subjected to a secondary vulcanization. The grinding wheel is brought into contact with the developing roller and is caused to rotate so as to perform an abrasive finishing on the surface of the developing roller. Second, a buffing member is moved along the length of the developing roller. The buffing member is in contact with the developing roller and is moved in the peripheral direction of the developing roller so as to perform buffing on the surface of the developing roller.

1. Field of the Invention
The present invention relates to a method of manufacturing a developing roller.
2. Description of Related Art
In conventional electrophotographic printers, the surface of a photosensitive drum is uniformly charged by a charging device. An exposing device emits light which illuminates the charged surface to form an electrostatic latent image on the surface. The electrostatic latent image is subsequently developed into a toner image by a developing device. The toner image is then transferred to a print medium. The print medium is subsequently fed to a fixing device where the toner image on the print medium is fused. The developing device includes a developing roller and a toner tank in which toner is held. The toner is applied to the surface of the photosensitive drum by the developing roller.
Conventional developing rollers use a resilient rubber-like material such as urethane or silicone as a matrix, mixed with a powdered resin such as silicone balls, silica, or glass pieces. These fine powdered resins have diameters in the range of 1 to 50 .mu.m.
The conventional developing roller is manufactured as follows:
A rubber matrix of 100 parts and a powdered resin of 130 parts having a particle diameter in the rage of 1 to 50 .mu.m are mixed together. The mixture is then kneaded. Thereafter, curing agent is added to the kneaded mixture and the mixture is further kneaded. The thus obtained material is then formed into a sheet as a sheeting material.
The sheeting material and an adhesive are applied to a shaft and the shaft is placed in a mold so that the sheeting material is subsequently shaped into a roller. Then the roller is subjected to coarse polishing to remove excessive sheeting material projecting from ends of the shaft. The coarsely polished roller is then subjected to secondary vulcanization, abrasive finishing, and final cleaning successively. After having cleaned finally, the roller is examined before shipping.
During the abrasive finishing, the coarsely polished roller is further polished to a predetermined diameter and a predetermined surface roughness so that the necessary amount of toner is applied to the photosensitive drum.
However, with the aforementioned conventional method of manufacturing a developing roller, particles of powdered resin are ground off the roller together with some of the matrix during the abrasive finishing. As a result, a sufficient number of particles of powdered resin are not left exposed on the surface of the roller. When the surface of the developing roller is ground, the matrix such as rubber plastically stretches to cover the particles of powdered resin as depicted by A-F in FIG. 11, so that the particles will be left partially covered after the roller has been cleaned. Therefore, a sufficient number of particles of powdered resin will not appear on the surface of the roller. Referring to FIG. 11, the particles are exposed as depicted by black areas A-F and covered as depicted by white areas a-f adjacent to the black areas A-F.
As a result, a new, unused developing roller has an insufficient surface roughness, allowing a correspondingly less amount of toner to be deposited on the roller surface. A larger number of particles of powdered resin will appear on the surface of the developing roller reaching a certain number of particles as a larger number of printing operations are performed. Therefore, more amount of toner adheres to the developing roller.
Thus, there will be a difference in print density between a new, unused developing roller and a roller having been used to print, for example, about 5,000 pages of paper.

Method of manufacturing developing roller


A cathode ray tube display device including unnecessary radiating magnetic field reducer which improves the ability to reduce an unnecessary radiating magnetic field, especially, generated by a vertical deflection coil. A pair of coil is disposed in opposing relationship on the opposite sides of the ferrite core along an X-axis or in the horizontal direction of the deflection yoke so as to be in contact with an open side end of the ferrite core. Each coil has a shape curved with a predetermined radius of curvature conforming to the shape of the outer peripheral surface of the ferrite core. The ferrite core acts as a magnetic material for the coils which reduces the unnecessary radiating magnetic fields to increase the coil inductances to thereby produce a large extremely low frequency magnetic field (ELMF) reducing effect.

The present invention relates to cathode ray tube display devices with unnecessary radiating magnetic field reducing means which reduces an unnecessary radiating magnetic field due to a magnetic field leaking from deflection coils wound around a deflection yoke of a cathode ray tube such as a display monitor, and more particularly to measures to be taken against an unnecessary radiating magnetic field from a vertical deflection coil.
Unnecessary radiating magnetic fields which will be produced around a CRT display device, Visual Display Unit (VDU), are said to be reduced to within a predetermined value because detrimental effects to human bodies and/or electronic devices present in the unnecessary radiating magnetic fields are required to be prevented. Especially, for an unnecessary radiating magnetic field in a low frequency band below 400 kHz, there is guidelines, for example, called TCO which stipulates that an extremely low frequency magnetic field (ELMF) of 5 Hz-2 kHz and a very low frequency magnetic field (VLMF) of 2-400 kHz should be restricted to within 200 and 25 nT!, respectively, at each of a measuring point on the periphery of a circle having a radius of 50 cm! at whose center the VDU is situated and a measuring point distant by 30 cm! from the CRT tube face.
Since a main source for generating an unnecessary radiating magnetic field of such a low frequency band is the deflection yoke, many display devices are proposed which reduce the unnecessary radiating magnetic field to within a stipulated value, for example, by providing means in the deflection yoke for generating a magnetic field which cancels the unnecessary radiating magnetic field.
As a specified example, an unnecessary radiating magnetic field reducing device disclosed in JPA-3-289029 is provided with a first cancel coil connected in series or parallel with the horizontal reflection coil, and a second cancel coil connected in a series or parallel with the vertical deflection coil, the first and second cancel coils being disposed around the deflection yoke, so as to generate a canceling magnetic field opposite to an unnecessary radiating magnetic field from the deflection yoke to cancel the unnecessary radiating magnetic field.
FIG. 10 shows this conventional unnecessary radiating magnetic field reducing device. Reference numeral 1 denotes the deflection yoke; 2 a deflection coil bobbin; 3 the vertical deflection coil; and 4 a magnetic ferrite core; 55a, 55b, 56 each the cancel coil which cancels the unnecessary radiating magnetic field. The cancel coils 55a and 55b connected to the horizontal deflection coil and the cancel coil 56 connected to the vertical deflection coil 3 generate magnetic fields which cancel unnecessary radiating magnetic fields generated from the horizontal and vertical deflection coils depending on the respective horizontal and vertical scanning frequencies, respectively, to reduce the unnecessary radiating magnetic fields.
The setting positions of the cancel coils are distant from the unnecessary radiating magnetic field generating sources in the conventional unnecessary radiating magnetic field reducing device, so that there are large unnecessary radiating magnetic fields around the VDU which cannot be canceled by the cancel coils.

Deflection yoke with coils for reducing unwanted magnetic field radiation


The present invention is directed to an improved network and system for a wireless communication system. The improved business method, operations method, network and system of the present invention includes the steps of delivering cellular services to the mass market, reducing peak capacity, increasing overall capacity utilization, improving capital utilization, providing an “all-you-can-eat” pricing model, and designing capacity based upon where the users live, work, and play.

Wireless communications services represent the fastest growing segment of the telecommunications industry worldwide. Although the Telecommunications Act of 1996 was intended to open the competitive environment in the United States, allowing many new entrants into 5 the local access loop, growth has been constrained by several factors. Some of these factors are endemic to any communications system (limited bandwidth, high capital costs, etc.). Other constraints are imposed by the business models that have come to be generally accepted in the industry. Most land line and wireless operators typically derive the majority of their revenues and profits from a relatively few—"heavy" and "business"—users of their networks. The heavy and business user segments have come to be considered the most desirable segment of the wireless customer population, due to their relative price inelasticity. Land line providers have typically focused on business users. Accordingly, per minute of usage pricing of cellular services has been adapted to that conventional business model, which was introduced in the late 1980's That conventional model, however, imposes constraints on operations and networks, and presents high usage charges to casual users. These patterns have, in fact, been favored by cellular operators due to the high profitability levels they offer.
A conventional wireless system of the type known prior to the present invention is described by Robert C. Raciti, in CELLULAR TECHNOLOGY (July 1995), which is incorporated herein by reference. Prior known cellular networks are typically constructed to achieve a relatively uniform level of coverage over a preselected service area. The service area is extended to a greater metropolitan area, namely, major population centers and major highway connections. Generally, the service area is specifically adapted to serve roaming traffic, which is billed at a higher rate. Consequently, roaming is favored in prior known systems. The service has been marketed on the breadth of coverage as well as complex features, targeted at the heavy and business users.
Network capacity is rationed, to avoid over use of the network, by maintaining pricing levels that tend to limit casual usage. Use is metered by price, and constrained by that pricing within the design limits of the system. When the existing wireless communications operators have looked at moving their market focus from the typical business users to a broader market, they have typically introduced prepaid services that allow the consumer to control the costs but have required very high per minute usage charges.
Wireless communications networks using this conventional business model typically comprise three basic components: Cell sites with RF base stations; Mobile Telephone Switching Offices (MTSO); and mobile phones that are provided to subscribers. Each base station contains a radio transceiver and controller, and provides radio communications to the mobile phone units operating in its cell. The cells are typically engineered into a network that is deployed in a hexagonal cell pattern, in order to provide local, regional, or national cellular coverage.
The MTSO links calls together using traditional copper, fiber optic, and/or microwave technology and acts as a central office exchange, allowing users to place a call on the local and long distance public telephone systems or mobile to mobile traffic. It allows mobile communication devices in the cell to dial out and alerts devices in the cell of incoming calls. The MTSO continuously monitors the quality of the communications signal and transfers the call to another base station that is better suited to provide communications services to the mobile device.
The mobile communication devices comprise hand-held phones, car phones, notebook computers, personal digital assistants, pen-based computers, palm-top computers, pagers, hand-held e-mail devices (such as those produced under the Blackberry™ brand), and portable data collection devices. The present inventors anticipate that, although the majority of cellular traffic has traditionally been voice communications, the relative proportion of traffic that comprises data, text, and potentially video, messages is increasing and is expected to increase dramatically in the coming years. The present invention is intended to work with all wireless communications devices. When these various types of mobile units communicate with the network, they must register with the system by subscribing with a wireless operator.
Most wireless operators of prior known systems have arrangements with other operators allowing users to roam. Roaming occurs when the mobile unit is outside the coverage area of their "home" cellular service provider and an alternative cellular provider handles the communication. Mobile units may also be connected to the Public Switched Telephone Network (PSTN) operated by an Incumbent Local Exchange Carrier (ILEC), Competitive Local Exchange Carrier (CLEC), Regional Bell Operating Company (RBOC), long distance carrier, or other telecommunications provider.
The radio spectrum used for wireless (cellular) communications comprises many bands that are allocated and used for commercial, personal, and military use. Fifty (50) MHZ of spectrum is allocated to cellular networks in the 824-849 MHZ and the 869-894 MM bands. This spectrum has been allocated into two 25 Mhz bands and has generally been allocated to very large service providers. Other bands of spectrum have been allocated for wireless communications. PCS is a wireless communications network that operates at a radio frequency of 1.9 GHz. This spectrum has been subdivided into three 30 Mhz and three 10 Mhz bands that are used by both large service providers and many new, more innovative service providers. The allocation of radio spectrum in the United States is described in the NTIA Manual of Regulations and Procedures for Federal Radio Frequency Management, Ch. 4, at 4-4 to 4-91 (2000), which is incorporated herein by reference.
Several types of network access are available in the United States including, without limitation: Advanced Mobile Phone Systems (AMPS), Time Division Multiple Access (TDMA) (in two formats), and Code Division Multiple Access (CDMA). AMPS is the cellular standard that has been extensively deployed in North America and has been commercially available since 1983. The current cellular standard describing access methods to the network is IS-553. It divides 50 MHZ of spectrum into 832 frequency channels, each 30 KHz wide. Various organizations, such as the Portable Computer and Communications Association (PCCA), modern manufacturers, computer manufactures, and service providers, have worked together in defining the IS-553 interoperability standard.
Time Division Multiple Access (TDMA) is a digital access method that allocates time slots to different users, allowing them to, share similar radio frequency channels. TDMA divides each frequency channel into six time slots and allocates two slots to each user. This time division of the carrier signal increases the network capacity by 300% (a factor of 3). Standard IS-54, currently upgraded to IS-136, describes a dual mode network access method allowing mobile units the choice of using TDMA or AMPS operation.
Code Division Multiple Access (CDMA) sends multiple messages over the same wide frequency channel that is decoded at the receiving end. Each mobile unit in a cell is assigned a different spreading sequence. This allows multiple users to share the same frequency spectrum. The use of CDMA increases network capacity by an order of magnitude (a factor of ten). CDMA network access standards are specified in standard IS-95, which is incorporated herein by reference. TDMA and CDMA digital access methods offer superior performance in terms of higher capacity, improved voice quality, encryption for communication privacy, and integration with digital terrestrial networks.
Cellular Digital Packet Data (CDPD) is a technology standard sponsored by the RBOCs and McCaw Cellular. CDPD overlays packet switching onto the existing cellular voice network, and transmits data packets over the idle capacity. This packet overlay is based on an Internet protocol backbone and does not need the call setup procedures that are required for switched voice calls. This makes CDPD adapted to short, bursty message applications, such as point-of-sale (POS) credit card verification, vehicle dispatch, package tracking, and e-mail. CDPD generally increases the network utilization, yet, excessive data traffic may cause interference with existing cellular calls.
There are a number of other wireless applications that may be used in conjunction with cellular telephony or separately: digital communications such as CDMA; cordless telephones; paging; specialized mobile radio (SMR); and satellite communication. Networks based on digital communications typically have a greater capacity than analog networks for carrying voice and data traffic than analog networks.
Michael E. Porter, in COMPETITIVE STRATEGY (1980), which is incorporated herein by reference, described various stages through which products progress through their life cycles: introduction; growth; maturity; and decline. Prior to the present invention, the cellular industry has remained in its growth phase. Some characteristics of Porter's growth phase are: growth in use; widening of the buyer group; improved reliability; competitive product improvements; increased advertising; increased channels of distribution; and high profit margins. The cellular industry has shared these features prior to the present invention. There are approximately 100 million cellular customers in the United States. Cellular service is growing at a rate of approximately 1 million new customers every month. The buyer group has widened, extending the initial buyer group of large businesses to include most businesses. System reliability has improved, greatly. There have been many competitive product improvements, such as digital technology advancements, voicemail, encryption, and enhanced battery life. Cellular products and services are featured widely in advertising on television, radio, print, and on the Internet. Alternate channels of distribution are also becoming more popular. For example, retail office supply, electronic, and computer chains are actively marketing cellular phones and services. Throughout this period of growth, cellular operators have enjoyed high profit margins.
McCaw Cellular was one of the early entrants into the wireless telephone market. The business model developed by McCaw (AMPS) has come to be generally accepted as the predominant business model for rendering cellular service, at least in the United States. A typical cellular system configuration of the type that was known prior to the present invention is described by Heith Knightson, in D1-CELLULAR NETWORK INFRASTRUCTURE—VOICE AND SHORT MESSAGE SERVICES, Telecommunications Standards Advisory Council of Canada (1997), which is incorporated herein by reference. As described by Knightson, AMPS is based on analog RF technology operating on frequencies 825-844 MHZ and 870-899 MHZ. The definitive standard for AMPS voice services is TIA IS-53 Cellular Features Description, which is incorporated herein by reference. The mechanisms to implement these services are given in TIA IS-41 Cellular Radio Telecommunications Intersystem Operations, which is incorporated herein by reference.
Prior to about 1997, AMPS was generally considered to be the main technology for providing mobile phone service. Currently, digital technologies, such as TDMA and CDMA have gained ascendency. These digital technologies offer improved voice quality and increased capacity. Standards have been promulgated for each technology, which are incorporated herein by reference. Although the technologies for TDMA and CDMA are different from AMPS, some of the equipment, infrastructure, and standards currently deployed for AMPS may be used in CDMA and TDMA networks. The radio portions (physical layer) of the mobile phones and base stations have been modified to support these new RF technologies.
The cellular network is viewed by the PSTN as an alternative End Office, where voice traffic originates and terminates. The interface between the PSTN and cellular network operates SS7 protocols, which are incorporated herein by reference. Within the cellular network, the signaling and voice traffic operate over separate trunking facilities, just as in the land line network. The SS7 protocol is used to carry signaling information over these out-of-band common channel signaling facilities. This separation of signaling and voice traffic is also preserved over-the-air. Between the mobile phone and the base station, the Forward Control Channel and Reverse Control Channel convey signaling information. Voice traffic is transmitted over the Forward Voice Channel and Reverse Voice Channel.
FIG. 1 illustrates the relationship between the cellular network infrastructure and the PSTN in wireless communications systems of the type that were common in the cellular industry prior to the present invention. The IS-41 messages are routed via Signaling Transfer Points (STPs). The STPs handle network routing. In particular, the route to the Home Location Register (HLR) for a specific mobile phone is handled by the STP. This has the advantage that, as the network expands and ranges of mobile phone numbers are assigned to different HLRs or new ranges come into service, only the routing tables in the STP need be updated. Mobile Switching Centers (MSCs) do not need to maintain full routing tables to all other MSCs. FIG. 2 illustrates the functions and interfaces that support voice services. The interface reference points are defined in the IS-41 standard, which is incorporated herein by reference, to ensure correct interoperation of equipment.
A typical cellular system prior to the present invention was understood to comprise the following functional elements:                Authentication Center (AC): The AC manages the authentication information related to the Mobile Station (MS). The AC may, or may not be located within, and be indistinguishable from an Home Location Register (HLR). An AC may serve more than one HLR.        Base Station (BS): The BS describes all of the radio equipment at a single location used for serving one or more cells. The Base Station comprises a Base Station Controller and the Base Station Transceiver systems.        Equipment Identity Register (EIR): The EIR maintains user equipment identity information. The nature, purpose, and utilization continues to develop and the present inventors intend that all such uses to which these components may be put are considered part of the present invention. The EIR may, or may not, be located within, and be indistinguishable from an Mobile Switching Center (MSC).        Home Location Register (HLR): The HLR is the location register to which a user identity is assigned for record purposes such as subscriber information (e.g. ESN, MDN, Profile Information, Current Location, Authorization Period). The HLR may, or may not be located within, and be indistinguishable from an MSC. The HLR may serve more than one MSC. The HLR may be distributed over more than one physical entity.        Integrated Services Digital Network (ISDN): The ISDN is defined by the appropriate ANSI T1 Standards, which are incorporated herein by reference.        Mobile Station (MS): The MS is the interface equipment used to terminate the radio path at the user side. It provides the capabilities to access network services by the user.        Mobile Switching Center (MSC): The MSC provides the interface for user traffic between the cellular network and other public switched networks, or other MSCs in the same or other cellular networks.        Public Switched Telephone Network (PSTN): The PSTN is defined by the applicable ANSI T1 Standards.        Visitor Location Register (VLR): The VLR is the location register other than the HLR used by an MSC to retrieve information for handling of calls to or from a visiting subscriber. The VLR may, or may not be located within, and be indistinguishable from an MSC. The VLR may serve more than one MSC.
The main feature of the cellular network voice service when compared with POTS (plain old 5 telephone service) is the geographical mobility of the phone. The equipment and interfaces depicted in FIGS. 2 and 3 perform two main functions. First, they transmit and receive voice signals over the radio spectrum. This is primarily the function of the Base Station and Mobile Station, which occurs over the Um interface. Second, they track where each mobile phone is within the cellular network. This is called "mobility management" and is performed by the MSC, referencing and dynamically updating the HLR and VLR databases. As shown in FIGS. 2 and 3, this occurs over the C, D, B, and E interfaces.
The interfaces and standards associated with these two functions of RF transmission and mobility management are distinct to cellular voice services. The other interfaces connect the cellular network to the existing land line telephone network (PSTN or ISDN), support authentication of users and equipment (AC and EIR), or support special features such as the Short Message Service (as shown in FIG. 3), that are not shown in the previous figures. These functions of network interconnection, security, and special services are not unique to the cellular network. Similar functions can be found in all land line telephone networks.
The generally accepted consensus standards applicable to wireless communications systems of the type known prior to the present invention are identified in Table 1, each of which standards are incorporated herein by reference:
TABLE 1Standards Applicable to Wireless Communications InterfacesApplicableCommentsInterfaceITU/ISOANSI/TIA/EIAA: BS to MSC interfacen/an/aIS-634Ai: MSC to PSTN interfaceX.25SS7IS-93-AB: MSC to VLR interfaceX.25SS7IS-41.2, IS-41.3C: MSC to HLR interface.X.25SS7IS-41.2, IS-41.3D: VLR to HLR interfaceX.25SS7IS-41.2, IS-41.3Di: MSC to ISDN interface?T1.611IS-93-AE: MSC to MSC interfaceX.25SS7IS-41.2, IS-41.3,IS-41.4F: MSC to EIR interfacenot definednot defined;H: HLR to AC interface.X.25SS7IS-41.2, IS-41.3Q:X.25SS7IS-41.2, IS-41.3Um: BS to MS interface, whichn/an/aIS-54-B (TDMA andcorresponds to the air interfaceAMPS), IS-88 AMPSIS-95-A CDMANotes:SS7 refers to the ANSI standards TL111, T1.112 and T1.114.X.25 refers to ITU Recommendation X.25 and ISO 8878, ISO 8208 and ISO 7776.Consensus standards for wireless communications networks have been promulgated by various bodies. Table 2 identifies the most prominent standards, each of which are incorporated herein by reference.
TABLE 2Wireless Communications StandardsANSI/TIA/EIA Standards:TIA/EIA-660Uniform Dialing Procedures and Call Processingfor Cellular Radio Telecommunications;Telecommunications Indus AssociationTIA/EIA-664Cellular Features Description; TelecommunicationsIndus AssociationTIA/EIA/IS-93Cellular Radio Telecommunications Ai-Di InterfacesStandard; Telecommunications Indus AssociationTIA/EIA/IS-41-C.1Cellular Radio Telecommunications IntersystemOperations: Functional Overview; TelecommunicationsIndustry AssociationTIA/EIA/IS-41-C.2Cellular Radio Telecommunications IntersystemOperations: Intersystem Hand-off Information Flows;Telecommunications Indus AssociationTIA/EIA/IS-41-C.3Cellular Radio Telecommunications IntersystemOperations: Automatic Roaming Information Flows;Telecommunications Indus AssociationTIA/EIA/IS-41-C.4Cellular Radio Telecommunications IntersystemOperations: Operations, Administration, and MaintenanceInformation Flows and Procedures; TelecommunicationsIndustry AssociationTIA/EIA/IS-41-C.5Cellular Radio Telecommunications IntersystemOperations: Signaling Protocols; TelecommunicationsIndustry AssociationTIA/EIA/IS-41-C.6Cellular Radio Telecommunications IntersystemOperations: Signaling Procedures; TelecommunicationsIndustry AssociationTIA/EIA/IS-732Cellular Digital Packet Data Specification;Telecommunications Indus Association.TIA/EIA/IS-634800-MHZ A-Interface Supporting AMPS, NAMPS,CDMA, TDMA Air Interfaces; Telecommunications IndustryAMPS:EIA/TIA-553Mobile Station-Land Station Compatibility SpecificationCDMA:TIA/EIA/IS-95A Mobile Station-Base Station Compatibility StandardDual-Mode Wideband Spread Spectrum Cellular System;Telecommunications Indus AssociationTIA/EIA/IS-97Recommended Minimum Performance Standards forStations Supporting Dual-Mode Wideband SpreadSpectrum Cellular Mobile Stations; TelecommunicationsIndus AssociationTIA/EIA/IS-637Short Message Services for Wideband Spread SpectrumCellular System; Telecommunications Indus AssociationDMH:TIA/EIA/IS-124Cellular Radio Telecommunications Intersystem NonSignaling Data Communications (DMH);Telecommunications Industry AssociationNAMPS:TIA/EIA/IS-88Mobile Station-Land Station Compatibility Standard forDual-Mode Narrow Band Analog Cellular Technology;Telecommunications Indus AssociationTIA/EIA/IS-91Mobile Station-Base Station Compatibility Standard for800 MHZ Analog Cellular; Telecommunications IndustryAssociationTDMA:TIA/EIA/IS-54-BCellular System Dual-Mode Mobile Station-BaseCompatibility Standard; Telecommunications IndustryAssociationTIA/EIA/IS-136800 MHz TDMA Cellular-Radio Interface-Mobile-Base Station Compatibility Standard;Telecommunications Industry AssociationANSI TI Standards:T1.111Signaling System Number 7—Message Transfer Part TPT1.112Signaling System Number 7—Signaling Connection Control Part SCCPT1.114System Number 7—Transaction CapabilitiesApplication Part TCAPT1.611 =Signaling System Number 7 (SS7)—Supplementary Services forNon-ISDN-SubscribersT1.209Operations, Administration, Maintenance,and Provisioning (OAM&P)—Network Tones and AnnouncementsITU-T Standards:T.50.International Reference Alphabet (IRA)formerly Alphabet No. 5 or IA5Other Related Documents:SR-TSV-002275Notes on the LEC Networks;Bell Communications Research Inc.TR-NWT-000776Network Interface Description forNational ISDN-1 Customer Access;Bell Communications Research Inc.In addition to the above services, many wireless communications networks also feature Short Message Service (SMS). SMS includes the following additional elements:                Message Center (MC): The MC stores and forwards short messages. The MC may also provide supplementary services for Short Message Service.        Short Message Entity (SME): The SME composes and decomposes short messages. The SME may be implemented in many ways, such as an operator assisted service or interactive voice response service. An SME may, or may not be located within, and be indistinguishable from, an HLR, MC, VLR, MS, or MSC.        The interface reference points in FIG. 4, which support the Short Message Service, are:—Interface M is the SME to MC interface;                    Interface N is the MC to HLR interface; and            Interface Q is the MC to MSC interface.
FIG. 3 depicts a cellular network, of the type known prior to the present invention, which further comprises a Message Center (MC) and Short Message Entity (SME), in addition to the infrastructure shown in FIG. 2. SMS is a data service available over the AMPS network. It is defined in IS-41, and is included under voice services because it is an integral part of the IS-41 specification. SMS allows a single packet of data to be transmitted to or from a mobile phone. SMS does not require packet fragmentation or re-assembly. Message integrity must be maintained across all interfaces, including the air (Um) interface. The SMS attempts to deliver the message whenever the mobile phone is registered on the cellular network, even when the phone is engaged in a voice or data call.
By early 1998, although the market continued in what Porter defines as its growth stage, some of the constraints imposed by the accepted cellular operation model had become apparent to the present inventors. Existing cellular business models in the United States had become stagnant. Only one business model as the McCaw, "AMPS" model—had come into widespread use and the growth of the wireless market had been limited to relatively price-insensitive users based upon that model. Accordingly, the present inventors perceived that known business methods limit future growth. These constraints include price, access to credit-challenged users, ability of users to control their monthly expenditures under prior billing models, high network operating costs, high back office support costs, high capital costs, low capital utilization, and other related limitations.
Capacity constraints were widely perceived to be a problem. Yet, the only apparent technical 5 solutions were approaches to expand peak system capacity. Techniques to utilize existing capacity more efficiently, or using emerging technology through modification of the business model, were unknown.
For example, Motorola and Qualcomm have both been very active in advancing the development of cellular technology. Kaschke, et al., U.S. Pat. No. 6,078,821, discloses a cordless radiotelephone system having an extendable geographic coverage area and a method therefor. Cukak, et al., U.S. Pat. No. 6,058,106, discloses a method for providing a centrally coordinated peer-to-peer wireless communications network. Smith, et al., U.S. Pat. No. 5,432,780, discloses a high capacity sectorized cellular communication system. Willkie, et al., U.S. Pat. No. 5,956,651, discloses a cellular telephone interface system for AMPS or CDMA data services. None of these solutions, however, sought to resolve any capacity limitations through modification of the basic McCaw-type, cellular business model, described above.
Hence, prior to the present invention, entrenched business and pricing models limited the attractiveness of cellular services primarily to business users, who were relatively insensitive to pricing. Average Revenue Per User (ARPU) of many cellular operators of these systems had stagnated. Most cellular networks were employing the same business and technical models, resulting in little relative differentiation between cellular operators. Operators typically resisted the incorporation of new technology. Changes in one portion of a regional or nationwide network could have implications for the entire network. Although most systems had been built to a relatively high peak capacity level, average capacity utilization in most systems was relatively low. Capital utilization was low. Customers were severely segregated based upon pricing. Pricing, in turn, tended to restrict usage.
The cellular industry typically characterizes usage patterns based upon the number of minutes a phone is used each month. Table 3 below, identifies typical usage patterns by the number of minutes used per month:
TABLE 3Traditional Market Segmentation Priorto the Present Invention Based uponMinutes of Usage (MOU)Minutes of UseAverage RevenueUsageper Monthper UserVery Heavy>500>$100Heavy400-500 min./mo. >$75Business200-300 min./mo.$40-75Consumer100-150 min./mo.$25-40Mass Market 15-20 min./mo.$15-25
In a cellular network of the type known prior to the present invention, the Mass Market customer group was considered sensitive to price, relative to heavy users. Prior to the present invention, due to the deficiencies of the generally accepted business model for cellular operations, marketing efforts were not generally devoted to this customer segment. Yet, this lowest customer segment (in terms of usage and ARPU) is also the most numerous. Customer growth of most systems, therefore, was inherently limited by their business models. Design limitations prevented them from expanding into the mass market.
These pricing constraints, and resulting constraints on overall usage, were simply accepted by most operators. These constraints enabled operators to reduce the overall system capacity to a lower relative level, with the anticipation that consumers would shift their personal economics to afford these pricing constraints. Yet, this model did not avoid the substantial capital cost of building networks to service peak capacity levels. Moreover, due to the slowness of incorporating new technologies, voice quality of cellular networks was generally considered inferior to that of wireline networks. Hence, the prior known cellular operations business models had failed to deliver cellular services to the mass market, to improve quality, to reduce peak capacity and, therefore, the capital requirements on system networks, or to increase overall capacity utilization.
Other business approaches had been tried but these too failed to deliver the benefits of the present invention. For example, in about 1995, PHS introduced in the Japanese market a strategy of pricing below other cellular providers and close to wireline providers. PHS was successful in so called "telepoint" applications in which subscriber density is very high. William Webb, UNDERSTANDING CELLULAR RADIO (1998), at 183-190, which is incorporated herein by reference.
The business model was well-received by consumers and the service enjoyed strong initial market penetration. The user demographics shifted rapidly from traditional business users to a mass market demographic user profile. Nonetheless, the PHS business model failed to deliver the unique advantages of the present invention for several reasons, including without limitation: unpredictability of the monthly costs; poor service quality do to inferior technology; and churn.
Users employed the service for brief periods, then abandoned it. This churn left the system operators with high initial costs of securing new customers and an insufficient time of retention of those customers to recover the acquisition cost through monthly service charges. This experience merely reinforced the conventional wisdom that the dominant business model, relatively high-priced cellular service through a network designed based upon coverage and designed to a high peak capacity usage, was the appropriate business model for wireless communications services.
Cellular networks have been deployed that incorporate some of the high capacity features of the present invention, but these network have been operated on the business model of prior known systems. For example, networks have been deployed in both Korea (Seoul) and Hong Kong that employ additional carrier signals to boost system capacity. Prior known cellular systems typically employed a single carrier signal. Adding additional carriers substantially increases system capacity. These two high capacity Asian cellular systems, are heavy usage CDMA systems designed around a convention cellular usage model, of the type known prior to the present invention. For example, the Seoul, Korea system features up to 6 carriers, on a CDMA network, using a substantial number of frequencies. The system is operated by SK Telecom and serves the metropolitan area in Seoul. Hong Kong had a AMPS and TDMA network. Hong Kong deployed the first CDMA network system. It, too, features numerous carriers and extremely high call capacity, due to the density of downtown Hong Kong.
Both of these known, high capacity systems, however, employed a conventional business model, operations method, network and systems approach. They are designed and operated based upon coverage, rather than capacity. They do not employ the "wireline call model" of the present invention. They do not include the business method, operations, network, and/or systems improvements to address capacity, namely, providing service primarily where people live, work, and play. Although these high-capacity networks in Seoul and Hong Kong featured multiple carriers and substantially more capacity than prior known systems, they did not include other of the unique features of the present invention. They are both "metered capacity" models, in which usage is billed based upon the number of minutes used.
As a result of the extensive experience of the cellular industry, by early 1998, the generally accepted business model for operating a wireless communications network involved: primary business users, numerous additional features for which surcharges applied, relatively high ARPU, and widespread system coverage to secure additional revenues from roamers passing through the system and paying higher roaming surcharge rates.
Neil J. Boucher, in THE CELLULAR RADIO HANDBOOK (1990), which is incorporated herein by reference, discloses a typical demand curve for a wireless system of the type known prior to the present invention. That curve is depicted in FIG. 4. Such a prior known wireless system has two peak times during the day. These occur at approximately 11 am and 7 pm, as illustrated in FIG. 4. In 5 addition, the changes in demand from peak time to low-usage time are significantly high. In contrast, the demand curve for a wireless system according to the present invention, as shown in FIG. 5, is relatively flat and does not have the peaks and significant deltas in demand that occur in prior known wireless systems. FIG. 5 illustrates a typical busy hour utilization of a preferred embodiment of a wireless system according to the present invention.
In 1997, the present inventors began development of a new business model for delivering wireless communications services. The present inventors developed a new method, operations, network, and system for delivering wireless communications services. This invention offered low cost cellular service to a more numerous mass market, rather than merely to a limited submarket of relatively price insensitive business users.
Prior known wireless communications operators typically targeted only high-end market segments, namely, heavy users and business users, and not the consumer or mass markets. ARPU values in the consumer ($25 to 40) and mass market ($15 to 25) were generally understood to be substantially lower than ARPUs' for business users ($40 to 75) and heavy users (>$75). There was no motivation to target lower ARPU customers prior to the present invention. Addressing these consumer and mass markets through prior business models would result in higher capital and customer acquisition costs, lower revenues, and lower profitability. Nor was it obvious that increasing market penetration in these consumer and mass market segments would increase revenues. Particularly in view of the high initial cost of acquisition and high operating costs of most cellular systems, customers at the low ARPU levels associated with the consumer and mass markets would have to be retained for long periods of time. Thus, the prior known business methods, operations, networks; and systems failed to address the unique problems addressed and resolved by the present invention.
The present inventors conducted extensive studies of the demand for cellular services. Based upon these investigations, the present inventors discovered that there were several basic flaws and omissions in the prior known business methods for delivering cellular services. Specifically, rather than being an unprofitable customer segment, the mass market and consumer markets could be viable, provided sufficient costs were driven out of the cellular operation.
This had not been done by prior known business methods. The present inventors discovered that, contrary to the conventional view, as unit price and monthly service fees fell, consumer interest (in the mass market and consumer market segments) increased to relatively high levels of penetration that would support a viable business model.
In order to be profitable, however, additional costs must be driven out of the traditional method of delivering cellular services. Specifically, the high operating costs, high capital costs, and relatively low capacity utilization characteristic of prior known systems each impeded the efficiencies necessary to serve these additional market segments. As the market had already demonstrated, the requisite degree of cost savings was not possible using the prior known methods of rendering cellular services.
The present inventors identified several critical factors in achieving the cost savings necessary effectively to expand cellular service to these additional market segments: improved capacity utilization and reduced peak system capacity; targeted area coverage; improved capital utilization; channels; reduced interconnect costs; improved back office operating efficiency; and improved network operating efficiency.
Particularly in view of a number of recent technical advances, capacity is highly dependent on the network technology employed. Webb, at 101-149, which is incorporated herein by reference. Several advances in recent years have enabled operators to enhance capacity from existing bandwidth and use bandwidth more efficiently, although other operators preferred legacy technology and the associated capacities. The present inventors believe that CDMA technology offers certain capacity advantages relative to rival technologies. Specifically, through the use of CDMA technology, the capacity of the system could be increased by a factor of two in terms of calls per sector, relative to rival technical formats. Similarly, the data rate can be increased from about 8 k to over 100 k, with projections of up to 2.4 Mega bits per sector. The present inventors anticipate continued advances in network capacity.
Coverage is one of the primary design criteria for any cellular network. Prior known networks are designed to provide extensive coverage for the basic service area, as well as for the surrounding area and major transportation arteries. Although the cost of this additional coverage is substantial, revenues from roamers, entering the system and using this extended coverage area 5 typically defray the added cost and generate substantial additional revenues in prior known cellular systems. The capacity and signal strength are optimized for coverage, and in particular, in-vehicle use. In addition, the capacity of prior known systems is typically built out to the peak demand of the system, throughout the service area. Although this results in higher capital cost, that capital cost is typically recovered through roaming charges.
The present inventors, however, have designed the system coverage based upon extensive market studies identifying patterns of living, working, playing, shopping, and schooling ("live, work, and play") of the primary service area. The system is designed to provide strong signal coverage, tailored to the usage pattern in each cell in the primary service area. The system of the present invention is preferably designed for in-building, as opposed to merely in-vehicle use. No 15 capacity is built into an extended service area or arteries. System coverage is designed specifically for local service, without regard to roaming. Nonetheless, major interconnection arteries are covered by the service of the present invention.
This provides two benefits. First, the coverage area of the present invention is typically more limited than coverage of systems of the type known prior to the present invention. FIGS. 8 and 9 are maps depicting coverage patterns of a system prior to implementation of a system according to the present invention and after such implementation, respectively.
Second, rather than building peak system capacity throughout the coverage area, the present invention tailors capacity within each cell to expected local traffic patterns. This allows a reduction in system cost. Fewer cells are built and the capacity of the cells that are built is increased relative to prior known systems. The present inventors believe that this approach enables the system to achieve effective coverage for the service area with only about 80% of the number of cell sites of prior known systems, when sites that are related primarily to highway and roaming coverage are removed.
Capital utilization is also enhanced by the present invention as the reduced coverage sites are provided and the cost of capacity is reduced through the use of CDMA technology. In a preferred embodiment of the present invention, the capital expenditure per subscriber is reduced, from 12 to 25% of the capital expenditure per subscriber in year 1 relative to prior known system, to 25 to 50% of the cumulative capital expenditure per subscriber in year 10. Moreover, due to the higher capacity utilization of the present invention, the difference between the present invention and prior known systems in terms of cumulative capital expenditure per unit of usage is even more substantial. The present inventors estimate that cumulative capital expenditure per unit of usage (Erlang) in year 1 preferably is only about 5% to 15% of prior known methods. In year 10, it is as low as one half.
Based upon these factors, the break even point for a network of the present invention is substantially sooner than for a network of the type known prior to the present invention. In the preferred embodiment of the present invention, the break even point is 12 months, as shown in FIG. 19. The calculations illustrated in FIG. 19 are based upon the "Typical PCS Company" model, as disclosed by the firm Donaldson, Lufkin & Jenrette in THE GLOBAL WIRELESS COMMUNICATIONS INDUSTRY (1999), which is incorporated herein by reference. The present invention may achieve break even at the end of year one, relative to year three in systems of the type known prior to the present invention.
Channel costs of marketing cellular services comprise one of the most significant cost elements for a cellular network. Cellular services of the type known prior to the present invention are typically highly diversified and segmented, featuring highly complex pricing plans and usage models. The selling activity requires highly trained customer service representatives to explain the various phones available, their features, and the relative benefits and disadvantages of the various service plans relative to a particular customers usage pattern. All of this adds substantial selling cost to a wireless operator. The present invention, in contrast, features one or two phones, a simple plan, and high volume usage. Rather than selling through specialized channels, the present invention may sell through mass merchandise outlets. Advertising and marketing efforts are oriented to the point-of-sale and limit sales personnel involvement. Each of these features further reduces the selling expense associated with the present invention.
Interconnect costs represent a significant cost factor to the system operator in systems of the type known prior to the present invention. Specifically, when users are charged by the minute, they tend to leave their phones off when they are not placing a call in order to avoid receiving charges for unwanted calls, or they avoid giving callers their phone number. This results in the system operator generating far more outgoing calls than are received within the system. In a typical cellular system of the type known prior to the present invention, the balance between calls generated by the user and calls received is approximately 75% outgoing; 25% incoming. This means that there is a greater chance of the user making a call to a number outside the service area than of receiving one from outside the service area. Interconnect charges, therefore, tend in the direction of the system operator having to pay to operators of other systems fees for outward bound calls made from users within-the system.
The present invention, however, seeks to reduce substantially interconnect charges by modifying the user's calling patterns. As the user enjoys unlimited use, without any additional charges for that higher use, the user tends to leave their phone on, even when they are not making a call. The present inventors have observed that usage patterns tend to be more balanced, in the range of 60/40 (20 point difference), in contrast to the 75/25 (50 point difference) balance observed in prior known systems. The present inventors believe that, over periods of several years, usage would migrate toward a balance of 55/45 or 50/50 in a preferred embodiment of the present invention. At that point, the interconnect charges will offset one another, eliminating this cost from the system.
Enhanced network operating efficiencies are another feature of the present invention providing a benefit relative to prior known systems. These benefits may include: reduced direct labor costs; reduced lease costs as a result of fewer, higher capacity cell sites; simplified operations; and improved back office operating efficiencies.
The present invention allows the operator to reduce the total number of cells in the system. This employs less expensive capital equipment and improves the efficiency of maintenance and repair activities, as both fewer cell are used and distance for traveling to the outlying cells that have been eliminated is reduced. As fewer cells are built into the system, lease costs are reduced for cell towers and cell sites. The cost of the fixed network and facilities are reduced relative to systems of the type known prior to the present invention.
The operating model of the present invention is preferably based upon monthly, bill-in-advance, pay-in-advance service, which is different then the pay-in-arrears system generally used for credit-worthy business customers or the prepaid system typically used for consumers. The operator, therefore, is not dependent on variable usage patterns, which result in fluctuating revenues. Revenues are based upon service and not the specific features employed from call to call. The revenue stream is leveled, offering the operator greater predictability and certainty.
Back office expenses are reduced dramatically, relative to prior known systems. One of the largest operating cost elements in prior known systems is customer service to handle billing inquiries. A typical cellular billing statement itemizes every call and details the various features (roaming, call waiting, etc.) accessed. This level of detail typically generates billing questions and challenges, all of which must be handled in a person-to-person discussion with the customer service department. The cost of handling this call volume can be one of the largest single cost elements in the back office operation of a typical prior known system. The present intention, however, eliminates these expenses. Credit checks are unnecessary. Account receivable balances are not permitted to accrue. As service is flat rate and pre-paid, there are no charges based upon the number of calls, length of calls, and features accessed. Itemized billing statements may be eliminated and replaced by simple flat rate bills. Accounts receivable and collection activities are eliminated, further simplifying back office operations.
Further, the present invention substantially reduces activation-related costs. The phones of the present invention are sold preactivated. Each phone already has loaded into it a unique cellular number upon leaving the factory. This reduces the effort required to activate. Rather than supplying skilled customer service personnel to assist in activation, activation may be conducted by the customer upon leaving the store. This Over the Air (Activation) Subscriber Provisioning (OTASP) feature of the present invention substantially reduces operations costs, and simplifies the customer's role in activating the phone. OTASP results in substantial cost savings to the system operator.
None of these improvements were obvious at the time the invention was made. In contrast, the incumbent business model has been and remains based upon minutes of usage, the time of day, and features accessed. Absent substantial elimination of costs from the existing model, the shift to lower ARPU users is not desired by system operators.
By combining these features in various combinations, to expand capacity utilization and reduce systems, capital, and operating costs, the advantages of the present invention are fully achieved.
In his recent book, Webb presents a simple and accessible primer on wireless communications systems. William Webb, UNDERSTANDING CELLULAR RADIO, Artech House, Inc. (1998), which is incorporated herein by reference. Webb describes a number of generally accepted network design factors prior to the present invention. Webb notes that prior known systems provided only enough capacity for the expected number of subscribers; if needed, additional capacity would be built into the system at a later date. Webb confirms, that prior to the present invention: "[t]o minimize system cost and roll-out time, operators need to insure that they use the fewest number of cells cites possible to provide the required coverage. The problems would be familiar to the cellular operators who expend considerable time and effort planning their networks to use the minimum number of base stations for the required coverage." Id. at 95. Webb further teaches that in cases where there was not sufficient capacity in the network, "the cells had to be made smaller." Id. at 98. Webb amplifies that "microcells are the only way to improve capacity in city centers." Id. at 99.
Yet, the present inventors have adopted a different approach to network design. By designing for capacity, rather than coverage, the present inventors have been able to further reduce the number of cells, without deploying substantial numbers of microcells. The present inventors have found that, by aggressively managing the cost of their wireless communications services and deploying appropriate technology, preferably CDMA technology, they have been able to increase capacity utilization of the network, dramatically reduce their operating costs, pass substantial savings on to the consumer (who enjoys not only greater access to their wireless communications service, but does so at a lower price), and enjoy ample margin to run the business profitably on a sustaining basis.

This patent is subject to a terminal disclaimer.

Method for providing wireless communication services and network and system for delivering same


An apparatus includes a presenting unit and a control unit. The presenting unit presents a plurality of options for interrupt printing along with an amount of incompletely printed sheet to be discharged while images are being printed on both surfaces of a continuous sheet in accordance with a prior job. The control unit interrupts, when one of the plurality of options presented by the presenting unit is designated, the prior job in timing according to the designated option to execute an interrupt job.

1. Field of the Invention
The present invention relates to a print control apparatus, method and program which cause printing by using a continuous sheet.
2. Description of the Related Art
In order to print images on both surfaces of a continuous sheet such as roll paper, there has been provided a technology in the past (see Japanese Patent Laid-Open No. 11-249346) which prints on one surface of a continuous sheet installed in a printing unit, then cuts the continuous sheet, temporarily reels it, and re-installs the continuous sheet to the printing unit. For efficient printing, such a printing apparatus performs printing on one surface for a plurality of pages continuously and performs printing on the other surface after the printing on the one surface for all pages. This procedure may realize efficient double-side printing. For example, a procedure as illustrated in FIG. 8A may be performed in order to perform double-side printing including printing four copies of five pages of images on a first surface and a second surface of a sheet. In other words, pages on the first surface of each copy are printed first. After the final page of the fourth copy is printed, a sheet is cut (801) and is reversed. Then, the second surface is printed from the fourth copy, and the first copy is printed last. Thus, the double-side printing for four copies is completed where a unit 802 is handled as one copy.
When an interrupt printing is performed in middle of a printing procedure as illustrated in FIG. 8A, there may occur problems as follows.
For example, as illustrated in FIG. 8B, a case may be assumed in which an interrupt job 2 (803) having two pages occurs in middle of printing on the first surface of the second copy. In this case, the sheet is cut in middle of the first surface of the second copy (after printing the third page in FIG. 8B, and the interrupt job 2 (803) is executed. Because the second surface of the first copy and second copy are not printed by the job 1 that has been executed before the interrupt printing, it results in an incomplete printed material (804). Therefore, printing (805) from the first copy is required again. This wastes the printing material before the interrupt occurs and lowers the printing efficiency because of performing the same printing process again.


The present invention relates to a marine propeller arrangement comprising a propeller communicating with a shaft connected to the motor of a marine vehicle, the propeller having a hub and demountable blades, wherein each blade comprises a hub portion being integral with each blade and having plurality of bores for securing thereof; and the arrangement comprises a sleeve having a shaft receiving bore, wherein each hub portion is supported by the sleeve and secured thereto via a plurality of securing elements.

The present invention relates to a propeller arrangement comprising a propeller with individual blades to be joined on a sleeve.
Thrust required for the movement of marine vehicles capable of traveling on the water such as boats, ships or capable of traveling under water such as submarines is provided by the propeller. Propellers generally comprise a hub portion and a plurality of blades connected to the hub. Surfaces of the propeller blades are generally provided with a helicoidal form and pressure is created by the compression of fluid, water, on the helicoidal surface after it is captured by the leading edge of the blade, then it accelerates over the blade and exits from the trailing edge. The path followed by the fluid over the blade and compression amount connected thereto affects the magnitude of the resulting thrust.
Propellers are conventionally cast in monolithic form and produced by being machined. In other words, blades are produced monolithic to the hub. This monolithic structure has some disadvantages. A). Blades cannot overlap each other for the removal of the propellers generally cast as a single piece from the mold and surface machining thereof and they can hardly exceed a surface area ratio of 1:1, remaining generally below the value of 1 (For example: 0.950, etc.). B). If one of the blades is damaged due to mechanical fatigue, external impact or any other reason, the entire propeller is discarded. In addition, the blades should be provided along the thickness of the hub (i.e. the depth-wise direction of the hub) in order to achieve maximum thrust from the blades arranged radially around the hub. Production costs of a very sensitive structure with such a complex geometry are high, because it requires detailed planning during and prior to the operation, benches or machines meeting the diameter of the entire propeller are required to be enormous and expensive units for fulfilling the size limits thereof.
There are known marine propellers having blades detachably connected to each other by securing mechanisms such as bolts. In this type of propellers, detachable blades are usually mounted and secured on the external surface of a cylindrical hub. Thus, hubs and blades are separately produced and then mounted for each separate boat. On the other hand, it is difficult to ensure a safe blade connection in the propellers with detachable blades. Blade connections can weaken over time.
For example, propellers with blades detachably secured to the hub are disclosed in the documents US2008/0166933, the entire contents of which is incorporated herein by reference, U.S. Pat. No. 6,537,031, the entire contents of which is incorporated herein by reference, and GB2328251A, the entire contents of which is incorporated herein by reference. Also, in the document JP 1237068, the entire contents of which is incorporated herein by reference, blades forming a propeller by means of a middle hub portion and manufacturing method of said blades and separate molding of the propeller blades are disclosed.
Propellers with detachable blades are also known in the prior art, wherein each blade is partially integral with a portion of the hub. For example, US2012114489, the entire contents of which is incorporated herein by reference, discloses a propeller with blades mountable to each other and partially comprising a portion of the hub at the joining end of the blades is disclosed. The propeller of US2012114489 should be separately designed for each separate vessel shaft and the rigidity of the blade connections is debatable.

Propeller arrangement for marine vehicles


A multilaser device has a first laser chip and a second laser chip produced from one and the same wafer lot, a common back beam sensor for receiving a first back beam and a second back beam emitted from the first laser chip and the second laser chip, respectively, and a package containing the first laser chip, the second laser chip and the back beam sensor.

1. Field of the Invention
This invention relates to a multilaser device suitably used in an electrophotographic apparatus and emitting a plurality of laser beams.
2. Description of Related Art
A multibeam laser has heretofore been of a monolithic construction provided with a plurality of light emitting portions on a laser diode chip. In an image forming apparatus of an electrophotographic type, a plurality of beams are caused to scan by the use of this multibeam laser, and are applied onto a photosensitive drum to thereby effect latent image forming.
In the above-described monolithic type, however, an electric current is supplied to one of the plurality of light emitting portions on the laser diode chip, whereby from the heat generation thereof, the threshold value electric currents of the other light emitting portions are increased and further, this leads to a reduction in the quantity of emitted light. This phenomenon is particularly remarkable in an increase in a driving current resulting from the heightening of a light output. In the image forming apparatus, such a reduction in the quantity of emitted light results in the uneven density of an image and deteriorates the quality of printing.
As one of methods of solving the above-noted problem, there is a method of carrying a plurality of laser diode chips to thereby form a multibeam, but this method gives rise to the problem that depending on the mounting accuracy of the laser diode chips in a semiconductor laser, the distance from a light emitting point to a photosensitive drum differs among the laser diode chips, whereby the converging property of a spot becomes uneven.

Multilaser device for receiving a plurality of back beams by a common sensor


A ring manufacturing method and a ring manufacturing apparatus according to the invention does not require the preparation of a specially shaped plate material for each type of ring plate to be manufactured. It is therefore possible to manufacture a ring plate of any thickness or width with a high degree of accuracy even in high-variety, low-volume production. In a plate material forming step, a round bar 1 is formed by rollers 3, 4 into a plate material having any desired cross-sectional shape. In a slant rolling step, the plate material is slant rolled by slant rollers 9, 10 and thereby formed into a specially shaped plate material whose thickness increases in the width direction from one side to the other. In a ring forming step, this specially shaped plate material is formed into a ring shape by a ring forming device 14. The specially shaped plate material can be formed on the ring forming production line, whereby the accuracy of the shape of the resulting ring is achieved without having to separately prepare a specially shaped plate material for each type of ring plate to be manufactured.

This invention relates to a method and an apparatus for manufacturing a ring with which it is possible to form a ring plate of any thickness, width, and internal and external diameter from the same starting rod material and which is suitable for high variety, low volume production.
Ring plates such as separating plates of wet multiplate clutches in automatic transmissions have generally been manufactured by being punched from a flat plate. However, with this method, the yield is poor. Also, while the realization of high performance and high quality in automobiles and the like has been progressing in recent years, a limit to reductions in cost has been reached.
To overcome this, a ring forming method has been proposed wherein a specially shaped plate material whose cross-section is tapered so that its thickness increases in the width direction from one side to the other is prepared and this specially shaped plate material is formed into the shape of a ring so that the thinner side thereof becomes the inner side and a ring having a uniform thickness is thereby obtained (Automobile Technology Society, Science Lecture Meeting Advance Notes 921 1992-5).
In this ring manufacturing method, deformation occurring in the formation of the ring is calculated, and the cross-sectional shape of the specially shaped plate material before it is formed into a ring is set so that the thickness, the width, and the internal and external diameters and so on of the ring plate being manufactured are obtained to a predetermined accuracy.
However, in the related art, this specially shaped plate material has been manufactured by drawing using a die. Consequently, when ring plates of various types having different thicknesses, widths, and internal and external diameters are to be manufactured, it has been necessary for different specially shaped plate material s to be selected and correspondingly different dies become necessary, and consequently high-variety, low-volume production has been expensive.
There have also been problems such as that:
(1) With a specially shaped plate material manufactured by drawing, because the working accuracy of an ordinary drawing die is about 0.05 mm and even with a drawing die worked using shape measurement about 0.02 mm as the limit, it is extremely difficult to obtain a highly accurate specially shaped plate material;
(2) Because the surface roughness of a drawn material is Rz=about 4.5, to obtain the surface roughness required of a ring plate, it is necessary for polishing or barreling to be carried out in a later step;
(3) With drawing, it is difficult to manufacture a thin plate and therefore drawing is not suitable for application to thin ring plates;
(4) With drawing, it is difficult to obtain a wide rod material; and
(5) The cost of the starting material constitutes a large proportion of the production cost.

Ring manufacturing method and ring manufacturing apparatus


Virtual machine administration for data center resource managers including discovering resources of the datacenter to be managed by a resource manager; determining, in dependence upon attributes of the resources, processing capabilities of the discovered resources; determining, in dependence upon attributes of the resources of the datacenter to be managed, memory capabilities of the discovered resources; determining, in dependence upon attributes of the resources, minimum memory requirements for managing the discovered resources; determining, in dependence upon attributes of the resources of the datacenter to be managed, minimum processing requirements for managing the discovered resources; deploying, in dependence upon the determined processing capabilities and memory capabilities upon one or more of the resources of the datacenter to be managed, a virtual machine having at least the minimum memory requirements and the minimum processing requirements; and deploying the resource manager on the virtual machine.

1. Field of the Invention
The field of the invention is data processing, or, more specifically, methods, apparatus, and products for virtual machine administration for data center resource managers.
2. Description of Related Art
Computer systems have become highly virtualized and often support resource managers to configure, maintain, and otherwise administer a large number of resources, typically in data centers. Because the resources may vary the requirements of the virtual machine that supports the manager of those resources may also vary. It is inefficient to deploy a virtual machine with capabilities that the resource manger does not need and it is inoperable to deploy a virtual machine without the capabilities that the resource manger does need.

Lenovo Enterprise Solutions (Singapore) Pte. Ltd.


Disclosed is a three-dimensional non-volatile ferroelectric memory including a ferroelectric memory array structure, wherein the ferroelectric memory array structure includes multiple layers of ferroelectric memory cell array disposed in a stacked way, and each layer of the ferroelectric memory cell array includes ferroelectric memory cells arranged in rows and columns; wherein word lines and bit lines which are substantially orthogonal to each other are oppositely disposed on two sides of the corresponding ferroelectric memory cell respectively, and a reference ferroelectric body is disposed adjacent to the corresponding ferroelectric memory cell. A polarization direction of an electric domain in the ferroelectric memory cell is not perpendicular to an electric field direction of a write voltage signal applied to the word line and the bit line; and when the write voltage signal is applied between the word line and the bit line.

Conventional ferroelectric random access memory (FRAM) is a non-volatile memory which stores data by using two different polarization orientations of a ferroelectric domain (or referred to as "electric domain") in an electric field as logic information ("0" or "1"), and can be also referred to as "ferroelectric memory".
A ferroelectric memory device based on domain wall conduction has been proposed by Anquan JIANG et al. For example, in U.S. Pat. No. 9,685,216B2 and US Patent Publication No. US2016/0358639A1, a storage mechanism of such a ferroelectric memory has been described, which is clearly distinguished from that of the conventional ferroelectric memory, and with which non-destructive readout of data based on current reading can be realized. Currently, in the ferroelectric memory device based on the domain wall conduction storage mechanism, on one hand, an ON-state read current is large, and can reach up to 10−7A to 10−6A; and on the other hand, a ratio of the ON-state current to an OFF-state current (namely, an on-off ratio) may be greater than 106, and the data retention performance is good. Therefore, the ferroelectric memory has received wide attention from the industry.
With the development of the applications of global Internet of Things, big data centers, smart homes, and portable devices, there are continuously increasing demands on the storage capacity and storage density of memory. For the conventional semiconductor memory chips, the storage capacity is increased by increasing the storage capability per unit area. However, in the Post-Moore era, bottlenecks such as the increased crosstalk between memory cells and the increased cost per word and bit become inevitable. Therefore, there is a need to seek breakthroughs and innovations in storage technology in terms of storage density, capacity, cost, and power consumption.
3D NAND is a revolutionary semiconductor storage technology, in which the storage density is increased by increasing stacked storage layers rather than reducing the two-dimensional size of devices, and the development space of the semiconductor memory is led into a third dimension, thus making the 3D NAND become a key to achieve a sustainable growth of the memory chip capacity in the future.

Three-dimensional non-volatile ferroelectric memory