The present invention is to provide a dicing method of cutting a workpiece along the first streets and the second streets by using a cutting blade having an annular cutting edge provided on the outer peripheral portion on one side surface of a base plate, the workpiece having plural first streets and second streets intersected each other at a predetermined angle. When the second streets are to be cut after the first streets are cut, the cutting blade is so positioned that the side of the base plate faces the side of the unworked region of the workpiece.

The present invention relates to a dicing method of cutting a workpiece into the form of a lattice by using a cutting blade having an annular cutting edge.
In the production of semiconductor devices, for example, a surface of a nearly disk-like semiconductor wafer is sectioned into plural rectangular regions by cutting lines called first streets and second streets that are arranged in the form of a lattice pattern, and a predetermined circuit pattern is formed on each of these rectangular regions. The plural rectangular regions on each of which the circuit pattern has been formed are cut into individual pieces to obtain so-called semiconductor chips. The cutting of the semiconductor wafer is usually carried out by using a precision cutting apparatus called dicing apparatus. The dicing apparatus is equipped with a cutting blade 54 that is shown in FIG. 5. The cutting blade 54 comprises a base plate (hub) 541 and an annular cutting edge 542 provided on an outer peripheral portion on one side surface of the base plate 541. The cutting blade 54 that is generally called hub blade is mounted being sandwiched between a flange portion 572 of a fixing flange 57 and a holding flange 58 by fitting the a plate 541 to a tool-mounting portion 571 of the fixing flange 57 attached on a rotary spindle 56 and then by screwing the holding flange 58 onto an end of the fixing flange 57. The workpiece is moved correlative to each other to the cutting blade 54 mounted on the rotary spindle 56 in a direction at right angles to the rotary shaft of the cutting blade 54 to execute the cutting.
The dicing method of cutting the semiconductor wafer into the form of a lattice pattern by the cutting blade 54 will now be described with reference to FIG. 7. In FIG. 7, reference numeral 11 denotes a semiconductor wafer which is the workpiece to be treated, and on the surface thereof are formed plural first streets 11a in parallel with each other and plural second streets 11b formed in parallel with each other in a direction at right angles to the first streets 11a .
Referring to FIG. 7(a), a semiconductor wafer 11 is so positioned that the first streets 11a are in a cut-feeding direction (that is a direction of moving a workpiece for cutting it) indicated by an arrow X and the cutting blade 54 is brought to a side edge of the semiconductor wafer 11. Here, the cutting blade 54 is set so that the side of the base plate 541 is on the side of an unworked region of the semiconductor wafer 11 which is the workpiece to be treated, i.e., that the side of the cutting edge 542 is located on the upstream side (upper side in FIG. 7) in an indexing direction indicated by an arrow Y1. Referring to FIG. 7(b), a forward cutting step is effected to cut the plural first streets la by sequentially and repetitively executing a cut-feeding for moving the semiconductor wafer 11 and the cutting blade 54 correlative to each other in a direction which is the cut-feeding direction indicated by an arrow X and an index-feeding for moving the cutting blade 54 in the indexing direction indicated by an arrow Y1 after one street is cut. After the forward cutting step has been finished, a rotational positioning step is executed to turn the semiconductor wafer 11 by 90 degrees as shown in FIG. 7(c), so that the second streets 1b are located in the cut-feeding direction indicated by an arrow X. At this moment, the cutting edge 542 of the cutting blade 54 is on the side of the unworked region of the semiconductor wafer 11 which is the workpiece, namely, the cutting edge 542 of the cutting blade 54 faces the downstream side (upper side in FIG. 7) in the indexing direction indicated by an arrow Y2. Then, referring to FIG. 7(d), the plural second streets 11b are cut by a return cutting step in which the cut-feeding for moving the semiconductor wafer 11 and the cutting blade correlative to each other in a direction which is the cut-feeding direction indicated by an arrow X and the index-feeding for moving the cutting blade 54 in the indexing direction indicated by the arrow Y2 after one street has been cut are executed sequentially and repetitively. According to the above-mentioned dicing method, a forward and return movement of the cutting blade 54 in the indexing direction (indicated by arrows Y1 and Y2) makes it possible to cut the semiconductor wafer 11 into the form of a lattice along the first streets 11a and the second streets 11b, whereby a very good productivity can be obtained.
In the above-mentioned dicing method, however, the cutting edge 542 of the cutting blade 54 undergoes great damage and becomes no longer usable before it is worn out. Therefore, the cutting blade must be frequently renewed, resulting in an increase of costs for the tools and for replacement.
The present inventors have conducted keen study in an effort to investigate the cause of damage to the cutting edge and have discovered the following fact. That is, though the semiconductor wafer is mounted on a frame via a tape, a pellet formed by the cutting in the forward cutting step may peel off the tape and fly when cutting of the wafer is performed by the cutting edge revolving at a speed as high as 20,000 to 30,000 rpm. The pellet 110 that peeled off may hit the outer peripheral edge 541a of the base plate 541 of the cutting blade 54 as shown in FIG. 6 to bite into the cutting edge 542 to damage the cutting edge 542. When the workpiece to be treated is a semiconductor wafer 11 of a disk-like shape, in particular, small and sharp triangular pellets are formed on the outer periphery by the dicing due to its disk-like shape. The sharp pellets 110 peel off easily because they are adhered at small contact areas on the tape 112, and bite into between the base plate 541 and the cutting edge 542 to damage the cutting edge 542.
Further, as a result of study by the present inventors, it was found that even when the pellets fly toward the side where the cutting edge 542 of the base plate 541 is provided and hit the cutting edge 542, the phenomenon shown in FIG. 6 does not occur since there is no base plate 541 and hence, the pellets that have flown do not bite into the cutting edge 542.
It is therefore an object of the present invention to provide a dicing method capable of preventing the cutting edge from being damaged by the flying pellets formed by the cutting.
In order to accomplish the above-mentioned object, according to the first invention, there is provided a dicing method of cutting a workpiece having plural first streets formed in parallel with each other and plural second streets formed in parallel with each other in a direction to intersect said first streets at a predetermined angle, along said first streets and said second streets by using a cutting blade having an annular cutting edge formed along the outer peripheral portion on one side surface of a base plate, wherein said dicing method comprises:
the first cutting step in which the plural first streets are cut by sequentially repeating the cut-feeding for positioning the workpiece so that the first streets are in the cut-feeding direction and for moving said workpiece and said cutting blade correlative to each other in the cut-feeding direction and the index-feeding for moving said workpiece and said cutting blade correlative to each other in an index direction at right angles to the cut-feeding direction to index the gap of said first streets;
a rotational positioning step in which after said first cutting step has been finished, said workpiece is turned by a predetermined angle to be positioned so that said second streets are in the cut-feeding direction, and said cutting blade is positioned at one side edge of said workpiece so that said base plate of said cutting blade faces the side of the unworked region of said workpiece; and
the second cutting step in which after said rotational positioning step has been finished, the plural second streets are cut by sequentially repeating the cut-feeding for moving said workpiece and said cutting blade correlative to each other in the cut-feeding direction and the index-feeding for moving said workpiece and said cutting blade correlative to each other in the index direction at right angles to the cut-feeding direction to index the gap of said second streets.
Further, in order to accomplish the above-mentioned object, according to the second invention, there is provided a dicing method of cutting a semiconductor wafer mounted on a frame via a tape and having plural first streets formed in parallel with each other and plural second streets formed in parallel with each other in a direction to intersect said first streets at a predetermined angle, along said first streets and said second streets by using a cutting blade having an annular cutting edge formed along the outer peripheral portion on one side surface of a base plate, wherein said dicing method comprises:
the first cutting step in which the plural first streets are cut by sequentially repeating the cut-feeding for positioning the semiconductor wafer so that the first streets are in the cut-feeding direction and for moving said semiconductor wafer and said cutting blade correlative to each other in the cut-feeding direction and the index-feeding for moving said semiconductor wafer and said cutting blade correlative to each other in an index direction at right angles to the cut-feeding direction to index the gap of said first streets;
the first rotational positioning step in which after said first cutting step has been finished, said semiconductor wafer is turned by a predetermined angle to be positioned so that said second streets are in the cut-feeding direction and said cutting blade is positioned at one side edge of said semiconductor wafer so that the base plate of said cutting blade faces the side of the unworked region of said semiconductor wafer;
the second cutting step in which after said first rotational positioning step has been finished, the plural second streets are cut over a half region from the one side edge toward the center of said semiconductor wafer by sequentially repeating the cut-feeding for moving said semiconductor wafer and said cutting blade relatively in the cut-feeding direction and the index-feeding for moving said semiconductor wafer and said cutting blade relatively in the index direction at right angles to the cut-feeding direction to index the gap of said second streets;
the second rotational positioning step in which after said second cutting step has been finished, said semiconductor wafer is turned by 180 degrees and said cutting blade is positioned at the other side edge of said semiconductor wafer so that the base plate side of said cutting blade faces the side of the unworked region of said semiconductor wafer; and
the third cutting step in which after said second rotational positioning step has been finished, he plural second streets are cut over the remaining half region from the other side edge toward the center of said semiconductor wafer by sequentially repeating the cut-feeding for moving said semiconductor wafer and said cutting blade relatively in the cut-feeding direction and the index-feeding for moving said semiconductor wafer and said cutting blade relatively in the index direction at right angles to the cut-feeding direction to index the gap of said second streets.


Methods for making skin panels suitable for use in aircraft structures and fuel tank structures, such as fuselages and reusable launch vehicle propellant tanks. A first method includes the following steps: machining a starting plate to a final part geometry; and explosive forming the machined plate to at least one of a uniaxial curvature and a biaxial curvature. A second method includes the following steps: explosive forming a starting plate to at least one of a uniaxial curvature and a biaxial curvature; and machining the curved plate to a final part geometry. Accordingly, the invention enables making integrally stiffened unitized axial load carrying skin panels that are either uniaxially or biaxially curved.

The current method of designing and constructing primary airliner structures, such as fuselages, is called semi-monocoque. The semi-monocoque structure contains thousands of detail parts riveted into substantially transverse stiffeners or ribs (also called frames) and into substantially longitudinal stiffeners or ribs (also called stringers), both of which are riveted to the skin. Although semi-monocoque structures have been successful for their intended purpose, it would be even more desirable to provide structures that are even less labor intensive, costly, and time-consuming to design, fabricate and assemble.
More specifically, the design phase for a traditional semi-monocoque jetliner requires designing thousands of details, splices, and assemblies and specifying a whole range of rivet types, their respective locations and spacing. Fabricating thousands of detail parts and maintaining configuration control while doing so can be extremely complicated. Accordingly, a great number of fabrication shops are typically employed to fabricate the various parts of a semi-monocoque design for a major airliner. Indeed, it is not uncommon for a commercial jetliner to contain about three million (3,000,000) holes drilled through parts with an equal number of fasteners installed, which is all done and orchestrated through and by over one thousand (1000) fabrication shops.
Assembling a conventional semi-monocoque aircraft involves riveting thousands of detail parts into the frames and stringers, which in turn are riveted into the axial load carrying skins. The complex assembly of thousands of such detail parts requires specifications, fabrication, and tracking of a whole range of rivet types and small parts, their locations, spacings, etc. for fastening the thousands of parts into the semi-monocoque structure. Accordingly, a great number of assembly shops are typically needed to assemble a conventional semi-monocoque aircraft. Indeed, it is not uncommon for nearly one hundred (100) assembly shops to be involved in the assembly of a commercial jetliner.
In view of the foregoing, it will be readily apparent that it would be highly beneficial to provide an aircraft structure that may be assembled with significantly less fastener holes, while those fastener holes which are still employed would facilitate a fully determinately assembled product requiring no or little drilling at the assembly operation.
Historical studies of aircraft indicate that fastener holes are the source or origination location for nearly all fuselage cracks, which tend to reduce the service life of the airframe. In addition, it is also known that fastener holes are the major culprit in the development of multi-site fatigue damage, fretting corrosion, and costly aircraft inspection, refurbishing and maintenance. With less fastener holes, less time would be needed for conducting routine inspections of and for repairing fastener holes to ensure the structural integrity of the airliner.
Providing an aircraft structure that is even less costly to design, fabricate, and assemble than the current semi-monocoque structures would be financially beneficial to both airframe manufacturers from the fabrication standpoint and to airline operators from the "Cost of Ownership" and maintenance standpoints. It is well known in the industry that "Cost of Ownership" has become the largest single fixed component of operating jetliner aircraft. The "Cost of Ownership" burden is shifting rapidly to the aircraft manufactures with the increasing airline industry trend toward leasing rather than owning jetliners.
Although airline structure costs and the affordability thereof are dependent at least in part on the time and labor required for and complexities associated with the design, fabrication, and assembly of the aircraft structure, other factors also are important. Aircraft structure costs, affordability and to a degree weight are driven not only by large part counts, but also by failsafe considerations and by stringer splice repair procedures. On the one hand, there is the increased cost of designing, testing and life demonstration; and on the other hand, wherever service life may be limited or reduced, there is naturally the increased cost of inspections and stringer splice repairs associated with large numbers of fastener holes.
Furthermore, the number of aircraft manufacturers owning commercial aircraft has increased as a result of the increasing trend of airline operators to lease rather than own commercial aircraft. Accordingly, it would be beneficial to such aircraft manufacturers to increase the service life and economically viable life limit of operating their commercial jetliner inventory. Thus, it would be beneficial to provide structures that are even more durable and damage-tolerant and have increased fatigue capabilities.
Accordingly, a need remains for methods of making skin panels that are suitable for fuselages and other primary aircraft structure wherein the skin panels and the aircraft structures formed therewith are even less labor-intensive and costly to design, fabricate, assemble, inspect and repair than existing designs. Ideally, the methods would provide skin panels that are capable of being used to form more durable and damage-tolerant structures with increased fatigue capabilities.
Regarding fuel tank structures, conventional fuel tank structures typically do not have as many parts as conventional semi-monocoque fuselages. However, the methods currently used for making fuel tank skin panels can be costly especially when the skin panels must be provided with biaxial curvatures. For example, a biaxially curved skin panel is needed for propellant tank dome or rounded end portion. Although machining of thick plates and spin forming are successful at providing biaxial curvatures to fuel tank skin panels, it would be beneficial to provide a less costly method of making the same. Accordingly, a need remains for a less costly and more efficient process for making biaxially curved skin panels that are suitable for use with fuel tank structures such as aircraft fuel tanks and RLV propellant tanks.

Methods of making integrally stiffened axial load carrying skin panels for primary aircraft structure and fuel tank structures


A device and method of using the device to assist in inserting a catheter in a female. The device includes a main body portion configured to be placed adjacent the pubic bone of a female, a pair of legs extending downwardly from the main body portion, a slot located between the legs, and a flange extending longitudinally along each of the legs. The flanges may extend along inner sides of the legs adjacent the slot. The device may also include a catheter guide formed at the upper end of the slot. The catheter guide may include a curved surface that extends along a portion of the main body member and each of the legs. The device may further include a gripping portion at an upper end of the main body. In one embodiment, the main body defines a plane, and the legs extend outwardly at an angle to the plane. A portion of the flanges may extend substantially transverse to the plane defined by the main body.

This invention relates to a catheterization assist device, and more particularly, to a catheterization assist device and method that may be used by a female for self-catheterization.
The use of catheters is well known to alleviate a variety of medical conditions that prevent the normal evacuation of the bladder. The catheter is a tube or device that can be inserted in the urethra of either a male or female and threaded into the bladder to permit the bladder to be emptied or evacuated therethrough. The insertion of catheters can be cumbersome, and in particular, the insertion of catheters in female patients may be complicated by the need to expose the urethra for insertion of the catheter. Additionally, some medical conditions require intermittent catheterization wherein a female patient may have to catheterize herself. In some instances, it may be difficult for the patient to expose and see the urethra and then to properly align the catheter with the urethra.
One prior art device is shown in U.S. Pat. No. 4,023,560 to Cade et al. This device is designed for obtaining a clean urine sample from a female, but it is also indicated that the device may be used to assist in inserting a catheter. The device disclosed by Cade et al. includes a generally U-shaped portion and leg portions extending transverse from the U-shaped portion. The U-shaped portion is designed for insertion into the vagina of a patient while the leg portions spread the labia. Cade et al. does not disclose that the device may be used by a female for self-catheterization.
Another prior art device is disclosed in U.S. Pat. No. 5,045,078 to Asta. The device disclosed by Asta is designated for use by a female for self-catheterization, and includes a vaginal insert and a catheter guide having a handle portion and an adjustment mechanism with an alignment hole. As with the device disclosed by Cade et al., use of the device disclosed by Asta requires inserting a significant portion of the device into the vagina of a patient, and furthermore, requires the patient to make adjustments of the adjustment mechanism to align the alignment hole with the urethra. The device in Asta does not assist in spreading the labia and the adjustment mechanism may impair vision of the urethra.
Another device for use in insertion of a catheter is disclosed in U.S. Pat. No. 4,834,711 to Greenfield et al. The device disclosed by Greenfield et al. is primarily designed to lubricate and disinfect a catheter to be inserted.
Another prior art device is disclosed in U.S. Pat. No. 5,084,036 to Rosenbaum. The device disclosed by Rosenbaum is suggested for use in self-catheterization of a female and includes a body portion, and a locating member with a handle portion. The device also includes a passageway with a tube for receiving a catheter. The device requires insertion of the body portion into the vagina, and also, requires a separate device for taking measurements to size the device to be used by a particular patient.
Another prior art device is disclosed in U.S. Pat. No. 5,653,700 to Byrne et al. The device disclosed by Byrne et al. is suggested for use in assisting in self-catheterization by a female and has a folding perforated catheter attached to a handle. The device disclosed by Byrne et al. uses a self contained perforated catheter and is not designed for use in assisting with the insertion of a standard catheter.
Yet another prior art device that is designed for use by females to assist in self-catheterization is disclosed in U.S. Pat. No. 6,544,240 to Borodulin et al. The device disclosed by Borodulin et al. includes a hub portion and a suction cup having a mirror-like film attached thereto. Borodulin et al. discloses that the female should use the mirror to locate the urethra and to align the hub portion of the device with the urethra so that the catheter can be inserted in the urethra through the hub.

Catheterization assist device and method of use


Determining relationships among objects represented in a database includes defining a plurality of tiles in the approximation of the first geometry by dividing the approximation of the first geometry in a first direction a plurality of times and dividing the approximation of the first geometry in a second direction perpendicular to the first direction a plurality of times. A second geometry is analyzed to determine if it fulfills a first filter condition with respect to any of the tiles defined in the approximation of the first geometry. If the second geometry fulfills the first filter condition with respect to any of the tiles defined in the first geometry carrying out a mathematical comparison of the first geometry and the second geometry.

1. Field of the Invention
The present invention relates to a method, a system, and a computer program product for accessing and utilizing information in a database. More particularly, the present invention relates to a method, a system, and a computer program product for determining relationships between a query object and objects in a database.
2. Description of the Prior Art
Databases are used to organize information according to any number of techniques. Database types include, but are not limited to, Quadtrees, B-trees, and R-trees. Each of these database types is more suitable for storing and organizing a particular type of data. Generally, R-trees are used to store multi-dimensional data. These R-trees store spatial objects formed by aggregating minimum bounding contours. Each node in an R-tree represents a region in space. A child node of a node in an R-tree represents a sub-region of the region in space represented by the node.
The number of objects that are aggregated in each node is permitted to range between m≦(M/2) and M, thereby leading to the use of the prefix (m, M) to characterize a particular R-tree and mirror the effects of a B-tree. The root node in an R-tree has at least two entries unless it is a leaf node, in which case it has just one entry corresponding to the minimum bounding contour of an object. The R-tree is height-balanced with the maximum height represented by logmr.
An R-tree is constructed in either a dynamic or a static manner. Dynamic construction of an R-tree builds the R-tree as objects are input into the R-tree. Static construction of an R-trees builds the R-tree after all the objects have been input into the R-tree. Statically constructed R-trees are usually characterized as being packed since knowing all of the data in advance permits each R-tree node to be filled to its maximum capacity.
An R-tree can include data concerning locations of features in space or on a surface. Spatial data can include geometric data that includes simple primitive elements such as lines, curves, polygons (with and without holes), compound elements that are made up of a combination of the primitive elements, and geographical data concerning the location of various objects in a region. Geographical data can include mathematical representations of counties, cities, homes, apartment buildings, parks, businesses, subway stations, and other features. The geographical data can be in the form of latitude and longitude or other data that defines position.
Once an R-tree is created it is typically desired to access and utilize the data stored in the R-tree. One way that the data in an R-tree is utilized involves determining the relative positions of particular objects, such as finding certain types of businesses in a zip code. The analysis of objects in spatial and/or geographic databases, such as R-trees, to determine relationships, such as overlapping regions and point-by-point continuity, is performed using sophisticated mathematical algorithms.
Typically, these mathematical algorithms implement a post-processing function to a candidate query result set to generate a final result set. The post-processing function includes loading each object in the candidate query result set and performing an exact point-by-point comparison of each object in the final result set with a query object. The loading of each object in the candidates query result set and comparing each object in the candidate query result set to the query object uses a substantial amount of memory and computing power, takes an unacceptable period of time, and costs a substantial amount of money.
Thus, there is a need for a method of determining relationships between a query object and objects in a database. There is a need for the method to reduce the number of geometries in a candidate result set. There is a need for the method to be applicable where query objects are large or small. There is a need for the method to decrease the amount of time required to execute the mathematical algorithm for determining relationships between objects. There is a need for the method to be applicable to large geographical databases.

This patent is subject to a terminal disclaimer.

Query prunning using exterior tiles in an R-tree index


A gradation driving circuit is provided that outputs gamma-corrected gray scale voltages. First and second multiplexors select first and second source voltages, respectively, in response to input data. The first source voltage is scaled by an appropriate factor corresponding to a required amount of gamma correction. The scaling factor is selected based on an additional output from the second multiplexor. The scaled first voltage is then subtracted from the second source voltage and the difference is output as the gray scale voltage. Alternatively, the gray scale voltage can be obtained by adding the first scaled source voltage and the second source voltage.

1. Field of the Invention
The present invention relates to a thin film transistor (TFT) liquid crystal display (LCD) and, more particularly to a gradation driving circuit which can output a large number of gray scale voltages in response to a minimum number of input voltages.
2. Discussion of Related Art
Generally, the TFT LCD module is a planar display, that is lightweight, thin, consumes little power, and has high contrast. Typically, the TFT LCD includes a back light which emits light through a matrix of pixels to the user. Each pixel includes three subpixels and associated color filters corresponding to the colors red, green and blue. Thus, for example, if a pixel were to emit blue light, the two sub pixels corresponding to the green and red filters are rendered opaque, while the sub pixel corresponding to the blue filter is made transparent. The human eye integrates light transmitted through the subpixels so that by selectively combining various combinations of the red, green and blue light, additional colors can be generated. Even more colors, however, can be displayed by further combining gray scales or gradations of each of the primary colors red, green and blue.
The gray scales are generated by supplying gray scale voltages to the individual sub pixels of the LCD, thereby causing the subpixels to have varying degrees of transmissivity. These gray scale voltages are output from a driver circuit capable of generating the requisite number of gray scale voltages at the appropriate levels.
TFT LCDs are commonly used in both audio video (A/V) and office automation (O/A) applications to display up to 512 colors using a 6-bit digital driver. As computers are increasingly being used in multi-media applications (transmission of both video and communication data) a wider range of colors are required. It has therefore been proposed that TFT displays generate up to 260,000 different colors by creating 64 gradations (or gray scales) for each of the primary colors red, green and blue. Although analog drivers, such as resistor ladders, can be used in certain A/V applications, a suitable driver for generating such a large number of colors in a high resolution O/A application has been difficult to realize.
A conventional gradation driving circuit of a liquid crystal display will be described below.
As illustrated in FIG. 1, the conventional gradation driving circuit includes a voltage source output part 1, a voltage source selection part 2 and an adder 3. The voltage source output part 1 outputs a plurality of different voltages. The voltage source selection part 2 selects the voltage source corresponding to the input data. The adder 3 receives and adds each voltage source output from the voltage source selection part 2, and outputs an appropriate gray scale voltage.
As shown in FIG. 2, the conventional output level selection circuit includes a plurality of source voltages V.sub.0 to V.sub.n (namely V.sub.0, V.sub.1, V.sub.2, V.sub.3, V.sub.4, V.sub.8, V.sub.16) each coupled to a respective one of a plurality of switches SW.sub.0 to SW.sub.n through one of resistors 24. Adder 3 is further provided to add various voltages supplied through selected ones of switches SW.sub.0 to SW.sub.n. Adder 3 can be realized with an operational amplifier 20 having its inverting input and output coupled to one another through resistor 22 and its non-inverting input coupled to ground. The voltage sum output of adder 2 corresponds to the gray scale voltage.
The operation of the conventional output level selection circuit will now be described. By way of example, if a gradation voltage corresponding to the 13th gray scale is to be selected, input data of 1011 (base 2), which equals 13 (base 10), is supplied to voltage selection part 2. The input data causes switches SW.sub.1, SW.sub.4, and SW.sub.8 to close, thereby coupling source voltages V.sub.1, V.sub.4, and V.sub.8, an input of adder 3. The 13th gray scale voltage is thus output as the sum of source voltages V.sub.1, V.sub.4, and V.sub.8.
FIG. 3 is a graph illustrating transmissivity of the LCD pixel (sub pixel) (T-V) as a function of applied gray scale voltage. As further shown in FIG. 3, due to the optical properties of the liquid crystal material, the relationship between applied gray scale voltage and transmissivity is not 15 linear, commonly referred to as the "gamma". Thus, the difference in potential between voltage V.sub.0 and V.sub.8 is not the same as the difference between voltage V.sub.8 and V.sub.16, for example. Accordingly, the interval between adjacent source voltages in the range of V.sub.0 to V.sub.8 is different than the interval between adjacent source voltages in the range of V.sub.8 to V.sub.16.
The conventional gradation driving circuit, however, outputs driving voltages that are spaced by the same interval across the range of V.sub.0 to V.sub.16. Thus, the conventional driving circuit does not compensate for the non-linearity of the transmissivity vs. gray scale voltage curve shown in FIG. 3, and does not provide "gamma correction".

Gradation driving circuit of liquid crystal display


There are provided a VSB receiver and a carrier recovery apparatus thereof, in which a carrier is recovered using a VSB modulated signal. In the VSB receiver, a digital processing part selects a desired channel frequency through an antenna, converts the channel frequency into an intermediate frequency, and digitalizes the channel frequency by passing a predetermined band of the intermediate frequency. A carrier recovery part extracts pilot signals by using a first LPF having a first bandwidth and a second LPF having a second bandwidth, and recovers a baseband carrier wave signal from a passband signal by using one of the extracted pilot signals. A clock demodulation part removes the pilot signal from the baseband carrier wave signal and extracts a synchronizing signal. A noise removing part removes a linear noise and a residual phase jitter of the baseband signal by using the synchronizing signal. A decoding part decodes the baseband signal whose noise is removed. Accordingly, the carrier recovery can be stably performed even when the pilot signal is weak.

1. Field of the Invention
The present invention relates to a digital TV, and more particularly, to a VSB receiver and a carrier recovery apparatus thereof, in which a carrier is recovered using a VSB modulated signal.
2. Discussion of the Related Art
A vestigial sideband (VSB) system of Grand Alliance is adopted as the standard for a transmission system of digital TV (e.g., HDTV) in the United States and Korea. In the VSB system, when a signal is amplitude-modulated, upper and lower sidebands are generated based on a carrier wave. At this point, when one of the two sidebands is greatly reduced, the other sideband is modulated. That is, only one sideband spectrum of a baseband signal is removed to a passband and then transmitted, such that the VSB modulation is more efficient in the use of bandwidth.
In the VSB modulation, if a DC spectrum of a baseband signal is removed to a passband, the DC spectrum is converted to a tone spectrum. This signal is called a pilot signal. That is, when a broadcasting station performs the VSB modulation, the pilot signal is carried and transmitted together via air so that a receiver can correctly demodulate the signal.
FIG. 1 is a schematic block diagram of a general digital TV transmitter. Referring to FIG. 1, a randomizer 101 randomly outputs an input data to a Read-Solomon (RS) encoder 102. The RS encoder 102 performs an RS encoding of the randomly inputted data for inner and outer channel coding and adds a parity code of 20 bytes to outputs the resulting signal to an interleaver 103.
The interleaver 103 interleaves the RS encoded data according to a preset regulation and outputs the interleaved data to a trellis encoder 104. The trellis encoder 104 converts the interleaved data into a symbol in byte for a trellis coding and outputs it to a multiplexer 105.
The multiplexer 105 performs a multiplexing of a segment synchronizing signal and a field synchronizing signal to a trellis coded symbol sequence per segment and frame to thereby form a frame, and then outputs the frame to a pilot insertion part 106. The pilot insertion part 106 inserts a pilot signal of a DC value into the framed transmission symbol and outputs to a VSB modulation part 107.
The VSB modulation part 107 modulates the symbol sequence having the pilot signal inserted thereinto in the VSB system and outputs the modulated symbol sequence to an RF up-converter 108. The RF up-converter 108 converts the VSB signal of the modulated baseband into an RF passband signal so as to effectively transmit the signal via an antenna.
FIG. 2 is a block diagram of the VSB modulation part of the digital TV transmitter shown in FIG. 1.
Referring to FIG. 2, a channel encoder 201 is configured with the randomizer 101, the RS encoder 102, the interleaver 103, the trellis encoder 104, the multiplexer 105, the pilot insertion part 106, and the VSB modulation part 107 includes a complex filter 202 and an intermediate frequency (IF) modulator 203. A signal passes through the channel encoder 201 and the VSB modulation part 107. First, for the VSB modulation, the signal passing through the channel encoder 201 passes through the complex filter 202. At this point, if the encoded digital signal passes through the complex filter 202, a Hilbert transformer and an SRC transforms the shapes of frequencies of I and Q signals such that the I and Q signals can be VSB-modulated.
The I and Q signals as the output of the complex filter 202 are IF-modulated at the IF modulator 203 and then subtracted at a subtracter 204, resulting in a VSB IF signal of a required bandwidth (6 MHz). In order to transmit the VSB IF signal via radio wave, the VSB IF signal is converted into an RF passband signal by the RF up-converter 205 and the RF baseband signal is transmitted via the antenna.
FIG. 3 is a block diagram of a general digital TV receiver based on the ATSC standard.
In the digital TV receiver, a passband signal of a specific channel is extracted by a tuner 302 and a carrier wave is recovered using a pilot signal inserted into a sideband. Then, a transmission symbol is extracted from the recovered baseband signal by a symbol timing recovery and a channel compensation.
Referring to FIG. 3, the digital TV receiver includes: a tuner 302 for selecting a desired channel frequency from the RF signal received through an antenna 301 and primarily converting the VSB signal from the RF band to an IF band; a surface acoustic wave (SAW) filter 303 for passing a predetermined band of the IF signal output from the tuner 302; an IF processing part 304 for secondarily converting an output signal of the tuner 302 into an analog signal; an analog-to-digital converter (ADC) 305 for converting the analog signal into a digital signal; a carrier recovery part 306 for converting the digital signal into a baseband signal; a DC limiter 307 for removing a pilot signal from an output signal of the carrier recovery part 306; a synchronizing part 308 for extracting a synchronizing signal from an output signal of the DC limiter 307 and recovering a symbol timing; a channel equalizer 309 for removing linear noise from the signal whose DC component is removed; a phase tracking part 310 for removing residual phase jitter from the signal whose linear noise is removed; and an FEC part 311 for decoding the signal, which is an operation opposite to the digital channel coding of the transmitter.
The tuner 302, the SAW filter 303 and the IF processing part 304 can be called an analog processing part, and the ADC 305 and the analog processing part can be called a digital processing part. Also, the DC limiter 307 and the synchronizing part 308 can be called a clock demodulation part 312, and the channel equalizer 309 and the phase tracking part 310 can be called a noise removing part 313.
That is, if a VBS-modulated RF signal is received through the antenna 301, the tuner 302 selects a desired channel frequency by using a heterodyne modulation system and then the VSB signal of the RF band carried on the channel frequency is lowered to a fixed IF band (generally, 44 MHz or 43.75 MHz) and signals of the other channels are properly filtered.
An output signal of the tuner 302 passes through the SAW filter 303, which removes signals of undesired bands and noise signals and serves as an analog matching filter.
For example, a digital broadcasting signal has all information within a band from the IF band of 44 MHz to a frequency band of 6 MHz, so that the SAW filter 303 removes all sections from the output signal of the tuner 302, except the band of 6 MHz in which information exists, and then outputs the remaining band signal to the IF processing part 304.
The IF processing part 304 converts the signal into an analog signal, and the ADC 305 converts the analog signal into a digital signal.
The passband signal converted into the digital signal is demodulated into a baseband signal by the carrier recovery part 306. In the baseband signal, a frequency of the pilot signal inserted for the carrier demodulation at the transmitter changes to 0 Hz, which is a DC component.
Since the DC component finished its role, the DC component is removed by the DC limiter 307.
Information of a synchronizing signal section is extracted by the synchronizing part 308. The information of the synchronizing signal section is used in the channel equalizer 309, the phase tracking part 310 and the FEC part 311.
The signal whose DC component is removed passes through the channel equalizer 309 to remove linear noises existing in the transport channel and the analog processing part of the receiver. Then, the signal passes through the phase tracking part 310 for removing the residual phase jitter and then it is decoded by the FEC part 311. If this process is finished, the digital TV receiver completes its function, and the transport stream equal to the signal inputted from the transmitter to the receiver is transmitted to a video/audio signal processing part (not shown).
FIG. 4 is a block diagram of the carrier recovery part of the digital TV receiver shown in FIG. 3.
In FIG. 4, the carrier recovery part 306 is implemented with a frequency phase locked loop (FPLL) proposed in the ATSC standard.
Referring to FIG. 4, if the passband analog signal is converted into the digital signal, a Hilbert transformer 402 shifts the signal by 90° such that the digital signal is transformed into a Q signal of an imaginary component. A delay unit 401 delays the digital signal by a predetermined time when the digital signal is transformed into the Q signal at the Hilbert transformer 402, and then outputs an I signal of a real component. A complex multiplier 403 multiplies the I and Q signals by an output signal of a voltage controlled oscillator (VCO) 410 to output a baseband I signal and a baseband Q signal. An FPLL includes a frequency locked loop (FLL) and a phase locked loop (PLL). The FLL includes an I signal low pass filter (LPF) 404, a delay unit 406, a code detector 407, a multiplier 408, a loop filter 409, and a VCO (or a numerically controlled oscillator (NCO)) 410. The FLL locks a frequency of the baseband I signal output from the complex multiplier 403. The PLL includes a Q signal LPF 405, the multiplexer 408, the loop filter 409 and the VCO 410. The PLL locks a frequency of the baseband Q signal output from the complex multiplier 403.
The I signal LPF 404, the delay unit 406 and the code detector 407 detect a frequency error, and the Q signal LPF 405 detects a phase error from the detected frequency error. Then, the multiplier 408 multiplies the frequency error and the phase error in order to obtain final frequency and phase error components (the controlled voltage).
The loop filter 409 removes RF components from the frequency and phase error components, and the VCO 410 converts an oscillation frequency according to the frequency and phase error components (the controlled voltage).
That is, the loop filter 409 filters only the baseband signal and the VCO 410 outputs the oscillation frequency varying according to the output signal of the loop filter 409. A beat frequency is removed by changing the frequency and phase of the carrier wave according to the varied oscillation frequency outputted from the VCO 410.
In the carrier recovery part 306, the I signal and the Q signal are demodulated and the frequency and phase are locked by separating the phase from the output signal of the SAW filter 303. Here, the center frequency of the VCO 410 is fixed to an intermediate frequency (for example, 46.690559 MHz) and the complex multiplier 403 multiplies the output of the VCO 410 and the output of the SAW filter 303 to thereby generate a baseband I channel signal i(t) and a baseband Q channel signal q(t).
At this point, the receiver can operate normally when the frequency of the pilot signal accurately is at the intermediate frequency (for example, 46.690559 MHz) at the output of the SAW filter 303. However, in many cases, the frequency of the pilot signal is not 46.690559 MHz.
Meanwhile, the output frequency of the VCO 410 is fixed to 46.690559 MHz. Thus, when the output frequency of the pilot signal is not 46.690559 MHz, there exists a beat frequency corresponding to a difference of two frequencies outputted from the complex multiplier 403. The FPLL is used to remove the beat frequency. That is, the frequency and phase of the carrier wave are changed due to the variation in the oscillation frequency of the VCO 410 and thus the beat frequency is removed. Accordingly, an object of the FPLL is to find a direction and magnitude of the movement of the oscillation frequency of the VCO 410.
The FPLL has a combination of a frequency locking look and a phase locking loop.
In FIG. 4, the frequency locking loop is configured with an auto frequency control filter (AFC), the code detector 407, the multiplier 408, the loop filter 409, the VCO 410 and the complex multiplier 403, and the phase locking loop is configured with the LPF 405, the multiplier 408, the loop filter 409, the VCO 410 and the complex multiplier 403.
FIGS. 5A to 5C are diagrams explaining a characteristic of the output signal of the complex multiplier and FIGS. 6A to 6C are diagrams explaining another characteristic of the output signal of the complex multiplier.
FIG. 5A shows a spectrum characteristic of the baseband I signal when the pilot signal is stably received, and FIGS. 5B and 5C show spectrum characteristics when the pilot signal component gets weaker while passing through the channel and therefore its position cannot be correctly found on the spectrum.
In the case of the FPLL that is dependent on the pilot, data component except the pilot component does not provide information necessary for the carrier recovery and also causes a jitter due to data after the carrier recovery. For these reasons, as shown in FIG. 4, the LPF is used to extract the pilot component from the received data.
When the pilot signal is weak due to the channel, it is preferable to use an LPF having a narrow bandwidth to extract the pilot signal from the data. However, if a carrier frequency offset exists due to the channel in such a state that the pilot signal is not weak, it is preferable to use an LPF having a wide bandwidth, as shown in FIGS. 5B and 5C. Meanwhile, if the component of the pilot signal is severely weak, even the LPF having the wide bandwidth cannot easily extract the pilot component.
FIG. 6A shows a spectrum characteristic of the baseband I signal when the pilot signal is stably received, and FIGS. 6B and 6C shows spectrum characteristics when the frequency offset exists in such a state that the power of the pilot signal is not weak and thus its position cannot be correctly found on the spectrum. As shown in FIGS. 6A to 6C, in case where the LPF having a narrow bandwidth is used, if the pilot signal is out of the narrow bandwidth, it is difficult to extract the pilot component.
According to the prior art, as described above, the LPF having the wide bandwidth is used to extract the pilot signal. Thus, when the frequency offset exists, no problem occurs. However, if the pilot signal is damaged due to the channel, power of the I signal from the complex multiplier becomes very weak near the DC. Therefore, in the system which performs the carrier recovery based on the pilot signal, its performance is degraded and thus the carrier cannot be recovered. If the LPF having the narrow bandwidth is simply used to extract the pilot signal, it is impossible to solve the problems occurring when the carrier frequency offset exists.

VSB receiver and carrier recovery apparatus thereof


A silicon carbide field effect transfer of the present invention includes a base and source region each formed by a series of amorphizing, implanting and recrystallizing steps. Moreover, the drain, base and source regions extend to a face of a monocrystalline silicon carbide substrate and the source and base regions comprise substantially monocrystalline silicon carbide formed from recrystallized amorphous silicon carbide. The source and base regions also have vertical sidewalls defining the p-n junction between the source/base and base/drain regions, respectively. The vertical orientation of the sidewalls arises from the respective implantation of electrically inactive ions into the substrate during the amorphizing steps for forming the base region in the drain and for forming the source region in the base region. The electrically inactive ions are selected from the group consisting of silicon, hydrogen, neon, helium, carbon and argon. A gate and gate insulating region are also provided on the face of the substrate above the base region. By applying an appropriate turn-on bias signal to the gate, a channel is created in the base region. The channel region electrically connects the source to the drain. The source and base are also electrically connected by a source contact on the face, opposite the portion of the base region wherein the channel is formed.

The development of semiconductor switching technology for high power applications in motor drive circuits, appliance controls, robotics and lighting ballasts, for example, began with the silicon bipolar junction transistor. As the technology matured, bipolar transistors became capable of handling large current densities in the range of 40-50 A/cm.sup.2, with blocking voltages of 600 V.
However, despite the attractive power ratings achieved by bipolar transistors, there exist several fundamental drawbacks to their suitability for all high power applications. First of all, bipolar transistors are current controlled devices. For example, a large control current into the base, typically one fifth to one tenth of the collector current, is required to maintain the device in an operating mode. Even larger base currents, however, are required for high speed forced turn-off. These characteristics make the base drive circuitry complex and expensive. The bipolar transistor is also vulnerable to breakdown if a high current and high voltage are simultaneously applied to the device, as commonly required in inductive power circuit applications. Furthermore, it is difficult to parallel connect these devices since current diversion to a single device occurs at high temperatures, making emitter ballasting schemes necessary.
The silicon power MOSFET was developed to address this base drive problem. In a power MOSFET, a gate electrode bias is applied for turn-on and turn-off control. Turn-on occurs when a conductive channel is formed in the base, between the MOSFET's source and drain regions, under an appropriate gate bias. As will be understood by one skilled in the art, the length of the channel is dependent on the rate of diffusion of the source and base dopants. The length of the channel is also an important design parameter in power MOSFETs because it has a strong influence on the on-resistance and the transconductance.
The gate electrode is separated from the device's channel by an intervening insulator, typically silicon dioxide. Because the gate is insulated from the channel, little if any gate current is required in either the on-state or off-state. The gate current is also kept small during switching because the gate forms a capacitor with the device's active area. Thus, only charging and discharging current ("displacement current") is required. The high input impedance of the gate, caused by the insulator, is a primary feature of the power MOSFET. Moreover, because of the minimal current demands on the gate, the gate drive circuitry can be easily implemented on a single chip. As compared to silicon bipolar technology, the simple gate control provides for a large reduction in cost and a significant improvement in reliability. An example of a known power MOSFET is the DMOS structure, illustrated at FIG. 1, and described in a textbook by coinventor Baliga, entitled Modern Power Devices (1987), p 265.
Power MOSFETs of the type herein described have typically been formed in silicon. However, because of the physical, thermal and electrical properties of silicon carbide, it is believed that power MOSFETs formed of silicon carbide may provide significant performance advantages over silicon power MOSFETs. This is because silicon carbide has a wide bandgap (2.2 eV at 300K), a high melting point (3103K, 30 atms), a small dielectric constant (9.3), a high breakdown field strength (2.5.times.10.sup.6 V/cm), a high thermal conductivity (1.5 W/cm-.degree. C.) and a high saturated electron drift velocity (2.times.10.sup.7 cm/sec.) compared to silicon, which is the most commonly used semiconductor material. These characteristics allow silicon carbide microelectronic devices to operate at higher temperatures and higher power levels than conventional silicon based devices.
In addition to the above advantages, silicon carbide power devices can operate with lower specific on-resistance than conventional silicon power devices. Some of the advantages of using silicon carbide for forming power semiconductor devices are described in articles by K. Shenai, R. S. Scott, and coinventor B. J. Baliga, entitled Optimum Semiconductors for High-Power Electronics, IEEE Transactions on Electron Devices, Vol. 36, No. 9, pp. 1811-1823 (1989); and by coinventors M. Bhatnagar and B. J. Baliga entitled Analysis of Silicon Carbide Power Device Performance, ISPSD '91, Abstr. 8.3, pp 176-180 (1991).
The process for manufacturing the silicon based DMOSFET device of FIG. 1 includes diffusing the P-base and N.sup.+ source regions into the substrate. For silicon, it is possible to obtain P-N junctions well beneath the surface of the substrate using diffusion, since diffusion rates for dopants in silicon are relatively high even at relatively low temperatures on the order of 1000-1200 degrees Centigrade. It is therefore possible to obtain P-N junctions in silicon as deep as 1-3 microns.
The ability to obtain deep junctions in silicon is an important feature in the design of power MOSFETs and, in particular, is a factor in determining the forward blocking capability and punch-through breakdown condition. For example, as will be understood by one skilled in the art, despite the short-circuiting of the N.sup.+ emitter to the P-base, via the source contact as shown in FIG. 1, the DMOSFET will conduct current under reverse bias as soon as the depletion layer in the P-base punches through to the N.sup.+ emitter and the N.sup.+ emitter begins injecting electrons into the P-base region. Because of the opportunity for punch-through, the shape of the doping profiles in the P-base and N.sup.+ emitter and the respective doping concentrations are important design considerations. A typical diffusion profile for the DMOSFET of FIG. 1 is shown in FIG. 2. The solid lines indicate the doping distributions, whereas the dashed lines show the resulting carrier concentration profiles, which differ from the dopant profiles as a result of compensation effects. The surface concentration N.sub.SP of the P-base diffusion and the N.sup.+ -emitter depth combine to determine the peak doping N.sub.AP in the P-base as indicated by the arrow. The depths of the P-base and N.sup.+ -emitter diffusions are respectively denoted as x.sub.P and x.sub.N+.
In addition to the above-mentioned design considerations including peak dopant concentration and profile, the channel length "L" between the edge of the source and drain regions beneath the gate is also important because it has a strong influence on the on-resistance of the device and the device's transconductance. Moreover, because of the need to maintain a low peak P-base concentration and a short channel length to achieve good on-state characteristics, conventional techniques for raising the punch-through threshold generally restrict the ability to obtain preferred on-state characteristics unless other steps can be taken to limit the peak concentration in the P-base region and simultaneously provide sufficient resident charge to prevent punch-through to the N.sup.+ emitter. With respect to FIG. 2, this would include steps to limit the peak concentrations in each region while also maintaining the total area under the respective curve for each region at the same value. To achieve this, more uniform doping profiles that extend as far into the substrate as the diffused profiles would be required.
In contrast to silicon, the diffusion coefficients of conventional P and N-type dopants in silicon carbide are small in the temperature range of 1000-1200 degrees Centigrade. In fact, temperatures on the order of 1500 degrees Centigrade and higher are generally required for diffusion to occur at appreciable rates. For example, in an invited paper by R. J. Trew, J. B. Yan and P. M. Mock, entitled The Potential of Diamond and SiC Electronic Devices for Microwave and Millimeter-Wave Power Applications, Proc. of the IEEE, Vol. 79, No. 5, pp. 598-620 (1991), temperatures on the order of 1900 degrees Centigrade were specified as being required for the diffusion of N or P-type dopants in silicon carbide. Unfortunately, this extreme range of temperatures is not compatible with the fabrication of integrated semiconductor devices having multiple layers of different conductivity type material. These temperatures are also considerably above the melting point of SiO.sub.2, a diffusion masking material having no commercially acceptable alternative for high temperature processing. Given these limitations, it is generally accepted that P-N junction formation arising from epitaxial growth or ion implantation with boron (B) or aluminum (A1) (p-type) or phosphorus (P) or nitrogen (N) (n-type) is most suitable for silicon carbide.
Unfortunately, although there has been a general acceptance of ion-implantation as a technique for forming P-N junctions in silicon carbide, problems including out-diffusion of dopant species, the precipitation of defect clusters, and the formation of electrically active line and point defects causing poor dopant ionization are encountered in the formation of lateral MESFETs and MOSFETs. For example, in an article by J. W. Bumgarner, H. S. Kong, H. J. Kim, J. W. Palmour, J. A. Edmond, J. T. Glass, and R. F. Davis, entitled Monocrystalline .beta.-SiC Semiconductor Thin Films: Epitaxial Growth, Doping and FET Device Development, 1988 Proc. 38th Electronics Components Conf., pp. 342-349, solid phase epitaxial re-growth of the amorphous regions caused by the implantation of boron was achieved by annealing at 1600 degrees Centigrade for 300 seconds. However, defect clusters of precipitates and vacancy loops formed near the center of the amorphous regions within the implanted region. Subsequent annealing at 1800 degrees Centigrade for 300 seconds promoted virtually defect free regrowth, but SIMS analysis revealed almost complete out-diffusion of the implanted boron ions.
The implantation of P or N-type dopant species also results in the formation of an implant profile having a peak concentration below the implant surface. As well understood by those skilled in the art, the implant profile can generally be approximated by a Gaussian curve, or for greater accuracy, a four-moment Pearson-IV curve. However, even after annealing, which may cause diffusion away from the peak concentration region, a non-uniform doping profile in the N or P-type region is present. Accordingly, it is difficult to achieve a great degree of uniformity in regions formed by ion implantation.
Thus, while ion-implantation may be used as a technique for forming regions of P and N-type conductivity in silicon carbide, it would be preferable to manufacture silicon carbide power MOSFETS that have more uniform deep-diffused junctions than obtainable using ion-implantation techniques alone.

Method of fabricating silicon carbide field effect transistor

North Carolina State University at Raleigh


A vehicle roof rack assembly (50) including a pair of clamp assemblies (11) that secure a roof rack bar (10) to the rails (12) of a vehicle having a roof over which the bar (10) is extend. Each clamp assembly (11) includes a pivotally mounted jaw member (26) that co-operates with a jaw (16) to engage the vehicle rail (12).

The number of new vehicles sold with factory fitted roof rails is increasing. These roof rails vary extensively with each vehicle. They range in profile, position and alignment on a vehicle. Known roof rack assemblies have a problem in that they are not always able to fit the variety of roof rails now available.
These variants also create a need for an adaptable roof rack product.


Disclosed is an optical frequency controlling device for ultra-dense wavelength-division-multiplexed optical channels in which center frequencies of optical channels are aligned. An optical frequency controlling device for ultra-dense wavelength-division-multiplexed optical channels of the present invention comprises an optical channel unit for outputting a plurality of semiconductor laser beams which have different center frequencies, the semiconductor laser beams forming optical channels; an optical detection unit for performing optical detection on the plurality of semiconductor laser beams outputted from the optical channel unit and generating beat frequency signals; a microwave spectrum analyzing unit for outputting spectrum information of the beat frequency signals outputted from the optical detection unit in a digital signal; and a controller for receiving an output signal of the microwave spectrum analyzing unit and controlling the center frequencies of the optical channels of the optical channel unit.

1. Field of the Invention
The present invention relates to an optical frequency controlling device for ultra-dense wavelength-division-multiplexed optical channels, and more particularly, to an optical frequency controlling device for ultra-dense wavelength-division-multiplexed optical channels in which center frequencies of optical channels are aligned.
2. Description of the Related Art
To increase the transfer capacity of a strand of optical fiber, the gaps between the optical channels of the wavelength-division-multiplexed optical system have been being reduced from 100 GHz to 50 GHz, 25 GHz or the lower. There is no noticeable standard for classification of ultra-dense optical communications, but if the gaps between optical channels are usually 25 GHz or less and the number of the optical channels is 100 or more, such a communication belongs to the ultra-dense wavelength-division-multiplexed optical communication. In bi-directional optical communication systems, the difference between the center frequencies of optical channels through which beams travels in opposite directions can be very small as 10 GHz. This case is regarded to belong to the ultra-dense wavelength-division multiplexed optical communication.
In the conventional wavelength-division-multiplexed optical communication system, a wavelength locker or a Fabry-Perot filter controls center frequencies. However, since such a method to use optical elements has generally an error of a few GHz, in the wavelength-division-multiplexed optical communication system having a very narrow optical channel gap, it causes a serious problem. To align the ultra-dense wavelength-division-multiplexed optical channel, NTT of Japan employed a method in which one light source is modulated with a frequency corresponding to the optical channel frequency gap. However, in this method, its signal-to-noise ratio is low for each optical channel so that it is difficult to utilize it actually. Recently, Fiberspace company of United States has developed an innovative wavelength locker that lowers its error to about 100 MHz. However, every optical channel requires the wavelength locker for itself so that the cost problem still remains. As a result, the solution for this field has not been made completely.
Today, the device in which microwave beat frequency signal generated when optical detection is performed for optical channels of different wavelengths is used as a control signal and the gap between optical frequencies of the optical channel sections is maintained to be uniform is suggested in the related art. Using this device, relative optical channel gaps between the nodes communicate with each other in the bi-directional optical communication can be controlled much more precisely than a general wavelength locker. This technology is disclosed in the following paper: Yong-Sang Ahn, Sang-Yuep Kim, Sang-Hoon Han, Jae-Seung Lee, Sang-Soo Lee, and Wan-Seok Seo, "Bidirectional DWDM transmission using a beat-frequency-locking method," IEEE Photonics Technology Letters, vol. 13, pp. 899-901, 2001. However, since this technology is proper to keep the relative frequency between different optical channel sections to be stable, this technology is not proper to align light sources to be used in the general ultra-dense wavelength-division-multiplexed optical communication other than the bi-directional optical communication.
The technology in which two or three light sources are aligned using beat frequency signals has been studied. Usually, the difference between an actual frequency of a beat frequency signal and the desired frequency of the beat frequency signal is converted into electric signal and the optical channel gap or the channel spacing is stabilized using the converted electric signal. For example, in the U.S. Pat. No. 5,861,975, the technology in which the beat frequency signal is converted into the voltage signal proportional to the beat frequency and the converted voltage signal is used to align the optical channel. This is a suitable method to align a few light sources but it cannot be used when the numbers of optical channels and beat frequency signals are large.

Optical frequency controlling device for ultra-dense wavelength-division-multiplexed optical channels


A directional center-fed half wave dipole antenna is constructed from a multilayer substrate (100) having dipole antenna elements (112, 142) disposed on opposite surfaces (113, 141) of the multilayer substrate (100). An energy reflector (160) is disposed on at least one side of the substrate (100) and positioned adjacent to the dipole antenna elements (112, 142). The dipole antenna elements (112, 142) are fed by a center feed member (122). Center feed member (122) has a tapered width so as to provide the necessary impedance matching. A ground plane is disposed within the multilayer substrate, the elements of which (114, 134) are positioned on both sides of the center feed element (122).

For portable communication devices such as, for example, two-way radios, pagers, radio telephones and the like, the prevailing industry trend is toward greater degrees of consumer market penetration. At the same time, the consumer markets are demanding smaller, faster, cheaper radio products. In recent years, in direct response to these market influences, radio components, amplifiers, filters, integrated circuits (ICs) and the like have experienced radical size reductions. The outcome has been a steady reduction in the size of consumer radio products. Unfortunately, similar gains in the antenna art have lagged well behind. Not surprisingly therefore, one of the largest components in a typical radio today is the antenna.
One relatively recent and promising development in the battle to reduce the size of consumer radio products has been the introduction of micro-strip technology into antenna design; namely, affixing miniature resonators on a dielectric substrate having a ground plane. While this approach has proven useful in applications where radiation efficiency is not extremely critical, it will be appreciated by those skilled in the art that the typical micro-strip antennae is not generally very efficient and may even be loosely characterize as a radio frequency (RF) polluter. If these antennas are going to find their way into consumer based products, however, they must be optimized to reduce RF energy deposition and increase radiation efficiency. Based on the foregoing, it would be extremely advantageous to provide a micro-strip antenna system that is inexpensive, easy to manufacture and well suited for use in the consumer market place.

Directional center-fed wave dipole antenna


A developer container includes: a developer container body including a developer supply port and a first shutter movement restriction groove on a surface of the developer container body; a shutter member movable from a close position to an open position of the developer supply port, the shutter member including a second shutter movement restriction groove such that the first and second shutter restriction grooves define a guide path when the shutter member closes the developer supply port at the close position; and a restriction member movable in the guide path and configured, when the restriction member is positioned in both the first and second shutter movement restriction grooves depending on an inclination of the developer container body, to prevent the shutter member from moving from the close position to the open position.

1. Field of the Invention
The disclosure relates to a developer container, a development device, and an image formation apparatus.
2. Description of Related Art
Electronic photographic printers, copiers, facsimile devices, multifunction machines, and the like are examples of types of conventional image formation apparatuses. In such image formation apparatuses, for example, in a printer, color development units are mounted as development devices. Each of the color development units includes a photosensitive drum, a charge roller, a development device, and the like. In the color development unit, the surface of the photosensitive drum is evenly charged by the charge roller and is exposed to light by a LED head to form an electrostatic latent image. The development device develops the electrostatic latent image to form a toner image. A transfer roller transfers the toner image onto a paper sheet and a fuser unit fixes the toner image to form an image. In such a way, the printer makes printing.
In the development unit, a toner cartridge as the developer container is detachably mounted to supply toner as a developer into the development device. For this purpose, the toner cartridge has a toner supply port as a developer supply port formed on a bottom surface of the toner cartridge. A shutter having an opening is provided to open and close the toner supply port. With this configuration, the toner supply port can be opened when the shutter is moved to cause the opening to meet or match up with the toner supply port.
For example, Patent Document 1 (Japanese Patent Application Publication No. 2009-229561) discloses a toner cartridge or a powder container that includes a shutter movement restriction member for prohibiting a shutter from moving when a toner supply port faces upward. This is to prevent foreign matter from entering the inside of the toner cartridge by a careless operation.

Developer container, development device, and image formation apparatus that have shutter movement restriction member to restrict movement of shutter member


The moisture content of soil may be determined using a swept-frequency microwave-based process and device. The process includes the steps of: producing a primary microwave signal with a varying frequency, splitting the primary signal to provide first and second microwave signals, which first signal is transmitted through an electric conductor in the soil where it will be delayed in proportion to the dielectric constant of the soil, while the second signal provides an internal reference signal, receiving a third signal which includes the first signal after it has passed through the electrical conductor, mixing the third signal together with the second signal, generating a mixed signal, filtering the mixed signal to remove upper side-band interference signals, generating a filtered-mixed signal, measuring the frequency of the filtered-mixed signal and calculating the moisture content of the soil.

1. Field of the Invention
The invention relates to an improved microwave system for measuring the moisture content of soil.
2. Description of the Prior Art
Evaluation of soil water content is a fundamental operation for irrigation scheduling in crop production, management and research. To date, the most effective method of measuring the soil water in the root zone is by the TDR technique. Numerous researchers over the last 20 years have shown the TDR technique provides a reliable measure of soil moisture through the estimation of the soil's dielectric constant, Heathman G. C.*, Starks P. J and Brown M. A. 2003. Other inventions based upon the TDR technique include U.S. Pat. Nos. 6,657,443, 5,726,578, 4,918,375.
In traditional TDR measurements, a rapid rise-time short duration, ns-pulse is transmitted down a transmission line to an open-ended buried waveguide sensing-structure where the signal undergoes a reflection back towards the signal source due to the mis-matched impedance of the end of the waveguide, i.e., the end of the buried structure. As the signal spends a portion of it's time traveling down the buried waveguide sensing-structure, the transit time of the pulse is delayed in proportion to the dielectric constant of the material surrounding this buried waveguide sensing-structure. The measurement consists of quantifying this variable delay to provide an estimation of the surrounding material's dielectric constant. As the TDR technique utilizes a very fast pulse that travels down the transmission line at a velocity equal to approximately 1/10 to ½ times the speed of light, in order to provide a reasonable dynamic range for the measurement, an extremely fast clock must be provided that operates at 100 to 1000 times this speed. Thus, the TDR technique while accurate, requires very expensive circuitry in order to accurately measure the delay (GHz or faster clock). This has lead to the TDR technique being predominantly used by only the research community at the cost of neglecting the bulk of the irrigation market that is comprised of growers, and landscapers. Given the difficulties in creating circuits to perform this measurement, even today and since 1980, the TEKTRONIX cable tester, model 1502, has been the instrument of choice for researchers seeking to obtain TDR or reflectometric measurements of soil moisture. This test instrument operates with a step pulse rise-time (the transition time a square wave takes to change the voltage from it's low level to it's maximum level) having 145 ps rise time (G. C. Topp and J. L. Davis, Measurement of Soil Water Content using Time-domain Reflectometry (TDR): A Field Evaluation. Soil Sci. Soc. Am. J., vol. 49, 1985,: 19–24). In an attempt to reduce the cost of TDR, several inventions have been developed that seek to slow down the pulse, such as U.S. Pat. No. 5,818,214, it should however be noted that this invention has only marginally reduced the demands of the requisite circuitry as it is still dependant upon the transmission of a marginally slower pulse.
Another disadvantage to the TDR method is due to the very broad frequency band-width the system requires due to the technique's use of a very rapid rise-time ns-duration pulse. This disadvantage is best illustrated by noting that the frequency spectrum of a pulse is extremely wide and when taken to the extreme with an infinitely narrow pulse-width, leads to an infinitely wide frequency spectrum. Thus, this technique is, by it's design, an extremely broad-band technique that cannot take advantage of the frequency-based variability that naturally occurs in the dielectric spectrum. Thus, the response of TDR is limited to an average response of all of these frequencies that produce a combined response that becomes the TDR measurement. Alternatively, a frequency based measurement that utilizes a small portion of a narrow bandwidth provides an additional ability to obtain more precise information as it's free to chose the band of interest to characterize the required trait of interest that is unavailable to the TDR user. As an example application where a frequency based measurement can out-perform TDR; it is well known that salinity provides a very strong response at low frequencies, kHz to low MHz, while conversely, at microwave frequencies the salinity response is very small in comparison to the strong signature provided by the water. Thus, the ability to tune the frequency to bands of specific absorbance allows for accurate independent characterization of more than one species such as measurement of both salinity as well as the soil water content, or the measurement of soil-water independently from the salinity levels present in the soil.
In an effort to reduce costs, other patents have taught alternative methods to TDR that seek to provide lower cost methods of measuring the dielectric constant of the soil; such as U.S. Pat. No. 5,148,125. The technique illustrated in U.S. Pat. No. 5,148,125 utilizes a buried loop transmission line coupled to a resonant circuit. Unfortunately, however resonant structures typically are extremely temperature sensitive and as such have had very limited success in the industry as well as the research community due to the difficulties in calibrating these types of instruments across the temperature range of interest and use. Other sensors have utilized resistance and capacitance probes in either timing or resonant circuits such as U.S. Pat. No. 5,341,673. The main trouble with these types of instruments lies in their inability to work at microwave frequencies which is where the effect of salinity no longer affects the measurement. Thus, these lower frequency systems are subjected to a dependence upon the soil's salinity as a confounding element affecting the reading.
U.S. Pat. No. 2,659,860 teaches a method to measure the moisture content of bales of material, by directing a 10 GHz microwave beam through the bale and receiving the beam with another antenna on the far side of the bale from the one which generated the signal. The moisture content of the bale is then determined solely from the attenuation of this signal.
Meyer and Schilz U.S. Pat. No. 4,361,801 teaches a sensing technique that requires measurements of both attenuation and the phase delay of propagation in order to calculate the real and the imaginary components of the complex permittivity measurement in order to measure moisture at 9 GHz which is independent of density. The basis for this measurement is the ratio of the complex permittivities providing, which is a modification of taking the ratio of the attenuation to the propagation delay, as the measure of moisture (either as phase delay or equivalently the time delay). Nelson et al. U.S. Pat. No. 6,147,503 describes another moisture sensor algorithm that provides a moisture sensor that is independent of density over the narrow range of densities provided by loose seed kernel samples versus tightly packed seed kernel samples. They teach a technique that operates at 11.3 and 18 GHz again using both the attenuation and the propagation delay to calculate the complex permittivity of the material to derive an algorithm for the determination of the moisture content of the material. Moshe et al. U.S. Pat. No. 6,476,619 describes a microwave cavity perturbation technique for the sensing of moisture and or density in cotton sliver that has a preferred operating range of 7–9 GHz. In the perturbation technique the system is setup with a resonant peak in the signal amplitude versus frequency plot and utilizes the frequency change in the location of this peak as the measure of permittivity change thereby providing a measure of the permittivity from which the moisture content can be estimated assuming a constant density of material. Moshe et al. U.S. Pat. No. 6,111,415 describes the use of the well known radar technique of Frequency Modulated Time Domain "FMTD" for use as a density sensor which is used to correct an attenuation based moisture sensor. Other patents by Moshe et al. include U.S. Pat. Nos. 5,845,529 and 6,107,809 which utilize a ratio of attenuation to phase delay measurement in a manner very similar to the Meyer and Schilz U.S. Pat. No. 4,361,801. The reoccurring theme between all of these patents is that they all use very high microwave frequencies, typically above 7 GHz, and all of them utilize a measure of the attenuation of the signal after it has been transmitted through the material under test as the primary measure of the moisture content. As such, all of these patents provide very expensive solutions.
However, despite these improvements, the need remains for a low cost, accurate technique for the determination of soil moisture content.

The United State of America as represented by the Secretary of Agriculture


A circuit device (10) includes a circuit construction unit (20) having logic circuit deployment areas (21) and (22) in which a logic circuit can be deployed, and a circuit controller (30) configured to deploy a designated logic circuit in a logic circuit deployment area, in which, if a logic circuit that is deployed in one of the logic circuit deployment areas is instructed to be rewritten to a new logic circuit, the circuit controller (30) deploys the new logic circuit in the other logic circuit deployment area, and, after deployment of the new logic circuit has ended, stops operation of the logic circuit that was initially deployed in the one of the logic circuit deployment areas.

An FPGA (Field Programmable Gate Array) is an integrated circuit that can be freely programmed by a user. In recent years, FPGAs have been adopted in various electronic devices such as digital cameras, camcorders, and hard disk recorders because of that characteristic.
Specifically, the FPGA includes a plurality of logic blocks, and various logic circuits can be constituted by electrically connecting the logic blocks in accordance with a program. Also, a portion of the logic circuit can be dynamically rewritten (partial reconfiguration) in the FPGA, and thus the FPGA can support changes in the specifications of electronic devices into which the FPGA is incorporated.
For example, Non-Patent Document 1 discloses an FPGA including a static area in which a non-rewritable logic circuit is constructed and a reconfigurable area in which a rewritable logic circuit is constructed. With the FPGA disclosed in Non-Patent Document 1, the logic circuit in the reconfigurable area can be rewritten by loading a file in which the circuit configuration is written.

Circuit device, circuit rewriting method, and computer-readable recording medium


A movable simulated golf green enables the practicing of approach shots on a golf driving range, or other location. The apparatus is constructed as part of a motorized vehicle so as to be driven about to various selected locations on the range. The green surface is made of a flexible sheet material laid over, but only connected to a structural under layer along its periphery. Thus an air layer pumped between the flexible sheet and the under layer causes the flexible layer to rise to a position slightly above the structural surface. The inner facing surfaces of these layers each have a metallic contact layer on them so that when they contact each other an electrical circuit may be closed. The electrical circuit provides a power source and several lamps for illuminating when a golf ball contacts the green surface and forces the metal layers into contact momentarily. The circuit is compounded so as to indicate by different color lamps, how far the ball impact on the green is from a flagpole positioned on the green. The apparatus also provides a ball pickup device which picks up stray golf balls and deposits them into a bin carried by the apparatus. The device is preferably remote controlled by radio commands from a fixed location and incorporates an on-board controller that steers the device to each new position on the golf range.

1. Field of the Invention
This invention relates generally to golf ball practice ranges and devices for the facilitation thereof, and more particularly to a motorized practice green movable to selected locations on the range for practice of approach shots and further to such an apparatus that further performs the duty of picking up stray golf balls.
2. Description of Related Art
The following art defines the present state of this field:
Uehara, U.S. Pat. No. 5,234,215 describes a golf practicing range that has a guide way provided on a field and a putting green provided on the field. The green is movable intermittently along the guide way. At each tee there is provided a distance indicator which displays the distance from the tee to the green every time the green stops at a predetermined point on the guide way.
Mueller, U.S. Pat. No. 4,202,547 describes a movable golf green which is movable along a predetermined track and the golf green is rotatable to provide a multitude of golf green simulation layouts and changing pin positions to the user of the apparatus.
Foley, U.S. Pat. No. 5,163,677 describes a golf-driving range for driving golf balls from any of a series of tee-points grouped together to a single common golf-driving fairway having a plurality of spaced apart greens each with a flagged hole, with preferably one of the greens being surrounded by a man-made pond of water, with also the plurality of greens being separated from the driving tee-points by a stream of water, and with sand traps and with assorted trees, shrubs and/or simulations thereof positioned preferably heterogeneously on the fairway, with at-least two sand traps positioned adjacent each of the spaced-apart greens, and a collection device including a centrifugal pump and a channeling device for separating and collecting golf ball that have fallen into the pond water, and detection and indicator mechanisms indicating onto which green a golf ball falls.
Williams. Sr, U.S. Pat. No. 5,219,161 describes an apparatus adapted for use as a green on a golf driving range wherein golf balls which land on the apparatus are prevented from remaining thereon. The apparatus includes a golf green surface having a perimeter in the shape of a golf green and an interiorly located cup opening The apparatus includes self-clearing means for preventing golf balls which land on the golf green surface so that golf balls inherently roll off of the green or by providing a mechanism which raises and lowers one end of the green surface in order to clear balls therefrom. The self-clearing green is well-suited for use on golf driving ranges where the clutter of golf balls on target greens reduces the value of the green as a realistic target for golfers using the range.
Meikle, U.S. Pat. No. 5,580,320 describes an artificial golf green designed for use at driving ranges. The target green structure is formed at an incline to provide users of the golf range the appearance of much larger target surface due to the perspective effects when viewing an inclined object from a distance. The construction of the target green is sectional to facilitate transportation. The landing surface includes artificial turf and energy absorbing pad for more realistic performance.
W.B. Crump, U.S. Pat. No. 3,520,727 describes forwardly divergent arms, held rigidly so as to form a throat at a conveyor frame, so as to swamp the balls on the ground toward an inclined table. A belt conveyor superimposed on the inclined table grips the balls and rolls them up the table so that the balls drop into a container, in which latter there are ball-carrying cages immersed in water. The golf balls are washed during the collecting operation by the forward motion and rocking of the container the unit is pulled by any suitable means such as by a motorized vehicle which is suitable tied to a cross bar connecting the divergent arms at their widest spaced end.
Heffley, Jr., U.S. Pat. No. 4,045,023 describes a game apparatus comprising a target with a plurality of target zones each of which is operatively connected to an impact responsive signal generator, a signal selecting circuit and a scoreboard by which objects impacting upon the target produce signals above an adjustable level that will register on the scoreboard. In a specific embodiment, the target may take the form of a simulated golf green and is combined with an all-weather golf driving range including a driving booth in which the environment is controlled, a fairway designed such that snow removal and ball retrieval are enhanced, and a device for registering the longer drives.
The prior art teaches the use of a movable simulated golf green and also teaches the use of golf ball pickup vehicles. However, the prior art does not teach a motorized golf green, ball picker combination. The present invention teaches such an apparatus and provides further related advantages as described in the following summary.

Moving practice green and ball pickup apparatus


A component mounting apparatus having a work conveyor-positioner unit is arranged on a supporting base to convey and position a substrate in an X direction. Supporting frames extend vertically from ends of the supporting base and face each other in a Y direction. The component mounting apparatus further includes a plurality of Y-axis tables extending between upper ends of the supporting frames, X-axis tables attached to movable portions of the Y-axis tables, and operating heads attached to movable portions of the X-axis tables to perform operations with respect to the substrate on the work conveyor-positioner unit. Each of the plurality of the Y-axis tables includes a movable portion at a lower part. Each of the X-axis tables includes a movable portion at a lower part and the operating heads are attached to a lower part of the movable portion of the X-axis tables.

Conventionally, there is widely and generally known an XY-robot component mounting apparatus configured to move a mounting head independently in an X direction and a Y direction, which includes a substrate conveyor-positioner unit to be arranged on a supporting base for conveying and positioning a substrate in an X direction (a right-to-left direction), supporting frames arranged in a standing manner on both ends in the X direction of this supporting base so as to straddle the substrate conveyor-positioner unit, Y-axis tables arranged in a Y direction (a back-to-front direction) on the both supporting frames, X-axis tables laid between movable portions arranged on upper or lower surfaces of the both Y-axis tables, a mounting head arranged on a movable portion provided on a front face of the X-axis table, and a component supplying unit or component supplying units arranged on any of a front part, a rear part, and both parts of the supporting base.
Meanwhile, there are also disclosed a component mounting apparatus including a plurality of nozzles provided on the mounting head for holding components by suction, and a component mounting apparatus provided with a plurality of mounting heads on the X-axis table so as to allow the respective mounting heads to mount components on corresponding substrates severally.
Various component mounting apparatuses of the above-described configurations are already well known (Japanese Patent No. 2858453, for example).
However, a typical XY-robot component mounting apparatus as described above is configured to repeat operations of holding a component by suction at the component supplying unit with the mounting head, then moving the mounting head in the X and Y directions and thereby positioning the mounting head in a position for mounting the component on the substrate, then mounting the component on the substrate with the mounting head, and then moving the mounting head back to the component supplying unit for holding another component to be mounted subsequently. Accordingly, an operation sequence required for mounting one component takes a long time. Therefore, in order to mount numerous components efficiently on a substrate, it is necessary to configure a mount line by arranging numerous component mounting apparatuses in the direction of conveying the substrate. In addition, the supporting frames for supporting the Y-axis tables are arranged on the both ends in the X direction and the mounting heads are configured to move inside the supporting frames in the X direction, resulting in enlargement of the component mounting apparatus in the X direction. Therefore, the mount line becomes extremely large and thereby develops problems of increases in equipment costs and high mounting costs.
Meanwhile, a regular type of component mounting apparatus configured to arrange an X-axis robot on a Y-axis robot develops a problem that the substrate size and the number of arrangement of component supplying means are limited if a width dimension in the X direction is set constant because of a restriction of a space for disposing the Y-axis robot and a restriction of a movable range for a mounting head on the X-axis robot. On the other hand, in order to secure the substrate size and the number of arrangement of component supplying means, the width in the X direction of the device is increased so that the device fails to achieve compact mounting equipment by reducing the width dimension of the device.
Meanwhile, when the plurality of nozzles are provided on the mounting head, it is possible to reduce operating time per component to some extent because it is possible to reduce the number of times that the mounting head moves between the component supplying unit and the substrate. However, since such reduction in operating time has a limitation, there is a demand for a component mounting apparatus which can achieve further enhancement in mounting efficiency and reduction in equipment costs.
Meanwhile, in the configuration of attaching the plurality of mounting heads to the X-axis table as well, an operation of holding components and a mounting operation still involve serial operations of the respective mounting heads. Although the operation efficiency may be improved to some extent as some of the operations can be carried out simultaneously, this component mounting apparatus is basically configured to perform the same mounting operation as the case of increasing the numbers of the nozzles. Therefore, the component mounting apparatus has a limitation of efficiency in the mounting operation, and also develops a problem that it is difficult to ensure mounting accuracy when the plurality of mounting heads are provided.
In view of the foregoing problems, it is an object of the present invention to provide a component mounting apparatus which is capable of performing operations efficiently and accurately while achieving a compact configuration.

Matsushita Electric Industrial Co., Ltd.