A light emitting diode is provided by the present invention which includes a pn junction-type light emitting unit having a light emitting layer (10) composed of n layers of a strained light emitting layer (12) and n−1 layers of a barrier layer (13), wherein when a barrier layer exists, the light emitting layer (10) has a structure in which one strained light emitting layer (12) and one barrier layer (13) are laminated alternately, n represents an integer of 1 to 7, and the thickness of the light emitting layer (10) is not more than 250 nm.

In recent years, plant growth using artificial light sources has been the subject of much research. In particular, cultivation methods using illumination from light emitting diodes (abbreviation: LED), which exhibit excellent monochromaticity, provide favorable energy conservation and long life, and can be easily miniaturized, are garnering much attention.
Based on the results of research to date, one emission wavelength band that has been confirmed as an effective light source for plant growth (photosynthesis) is red light having a wavelength within the region from 600 to 700 nm.
Light within the wavelength vicinity of 660 to 670 nm exhibits particularly favorable reaction efficacy for photosynthesis, and is thus a preferred light source. In order to generate this wavelength, light emitting layers composed of AlGaAs or InGaNP or the like are currently being investigated (for example, see Patent Documents 1 to 3).
On the other hand, compound semiconductor LEDs having a light emitting layer composed of an aluminum-gallium-indium phosphide (composition formula: (AlXGa1-X)YIn1-YP, wherein 0≦X≦1 and 0<Y≦1) are also known.
Among these types of LED compound semiconductors, a light emitting layer having the composition Ga0.5In0.5P exhibits the longest wavelength, and the peak wavelength obtained from this light emitting layer is in the vicinity of 650 nm.
Further, generally, a light emitting unit having a light emitting layer composed of (AlXGa1-X)YIn1-YP (wherein 0≦X≦1 and 0<Y≦1) is formed on a monocrystalline substrate of gallium arsenide (GaAs), which blocks the light from the light emitting layer and is not particularly strong mechanically.
Accordingly, much research is being conducted with the aims of obtaining higher brightness visible light LEDs, and achieving further improvements in the mechanical strength of these devices.
For example, Patent Document 4 discloses a so-called bonded LED prepared by removing the substrate material such as GaAs that blocks the light from the light emitting layer, and then bonding a support layer which is formed from a material that can transmit the light from the light emitting layer and exhibits excellent mechanical strength.
Patent Document 5 describes investigations that have been conducted, for laser devices having a different light emission mechanism, into light emitting layers having strain (hereafter also referred to as "strained light emitting layers"). However, there are currently no practical applications of strained light emitting layers in the field of light emitting diodes.
Patent Document 6 discloses the application of a quantum well structure to the light emitting unit of a light emitting diode. However, because the quantum effect obtained by utilizing a quantum well structure shortens the emission wavelength, this technique cannot be applied to techniques requiring wavelength lengthening.

Light emitting diode and light emitting diode lamp


A method and apparatus is provided for real-time detection of trace amounts of atmospheric and tropospheric halogen-containing compounds. The present invention can be used either for in situ detection or remote sensing. A laser is employed to induce photofragmentation of the halogenated molecules and facilitate detection of the characteristic atom fragment by stimulated emission spectrometry. For brominated compounds, the output of a single laser is tuned to the strong two-photon 4p.sup.4 5p .sup.4 D.degree..sub.3/2 .rarw.4p.sup.5 2 P.degree..sub.3/2 transition of Br at 260.634 nm. The Br atoms are subsequently detected by stimulated emission (SE) via the 4p.sup.4 5p .sup.4 D.degree..sub.3/2 .fwdarw.4p.sup.4 5s .sup.4 P.sub.5/2 transition at 844 nm. For comparison, the laser-induced fluorescence (LIF) signal at the same wavelength is also monitored. The SE signal is distinct from the fluorescence in that it is coherent, bidirectional, and propagates coaxially with the laser beam. As a result of photophysical amplification, it is approximately two orders of magnitude greater than the LIF signal. The present invention has been demonstrated for trace detection of CHBr.sub.3 and CHClBr.sub.2 in N.sub.2 or air at total gas pressures of 1-760 Torr. Detection limits are in the parts-per-million range. The absorption cross section of the two-photon 4p.sup.4 5p .sup.4 D.degree..sub.3/2 .rarw.4p.sup.5 2 P.degree..sub.3/2 transition is estimated to be 3.8.times.10.sup.-43 cm.sup.4.

In situ or remote detection and monitoring of trace amounts of halogen-containing compounds in real-time is critical to the safety of humans, wildlife, and the environment. Volatile halogenated organic compounds, particularly those containing chlorine (Cl) or bromine (Br), are of considerable environmental importance due to their stratospheric ozone depletion properties, their contributions to the global greenhouse effect and their utility as indicators of biological inputs in biogeochemical studies of marine and atmospheric systems. There are also developing concerns that chlorinated organics cause cancers in adults and adverse health and reproductive effects in the offspring of both humans and wildlife. As a result, the development of monitoring methods for halogenated species has received increasing attention.
The most common method used to determine halogenated species under ambient conditions is cryogenic preconcentration of the sample followed by gas chromatography with electron capture detection (GC-ECD). The method is very sensitive, part-per-trillion (ppt) in level, with absolute limits of detection of the halogen atom on the order of 1-100 pg, depending on the compound. Despite high sensitivity, the GC-ECD technique requires extensive sample manipulation and a long measurement cycle, typically about one hour. Other methods of detection include mass and ion mobility spectrometry. Although these methods are also sensitive, they are not conducive to real-time, in situ measurements since the sample needs to be retrieved into an analysis chamber. In addition, acquisition and analysis is relatively slow and the prior-art apparatus is not readily portable due to its size.
Laser-based methods offer the advantages of high sensitivity and speed for the real-time monitoring of small species such as atoms, diatomics, and triatomics. These methods include laser-induced multiphoton ionization and laser-induced fluorescence. These methods currently enjoy limited applications. Many halogen containing compounds are large and lack distinguishing spectral features or absences of any features in the ultraviolet-to-visible (UV-Vis) spectral region. In addition, dissociation processes of the target molecules subsequent to laser excitation competes with ionization or fluorescence processes, causing a decrease or absence of ionization or fluorescence detection signal. As a result of these limitations, other approaches have been sought to overcome these obstacles.
One successful approach involves the use of the laser photofragmentation/fragment detection spectrometry. Selected references include: (1) U.S. Pat. No. 5,364,795, issued to Sausa et al. on Nov. 15, 1994; (2) Simeonsson, Lemire, and Sausa, "Trace Detection of Nitrocompounds by ArF Laser Photofragmentation/Ionization Spectrometry," Applied Spectroscopy, Vol. 47, No. 11, p. 1907, 1993; (3) Simeonsson, Lemire, and Sausa, "Laser-Induced Photofragmentation/Photoionization Spectrometry: A Sensitive Method for Detecting Ambient Oxides of Nitrogen," Analytical Chemistry, Vol. 66, No. 14, p. 2272, 1994; (4) Simeonsson and Sausa, "Trace Detection of Ambient Brominated Compounds by Laser-Induced Photofragmentation Detection Spectrometry," Spectrochimica Acta, Vol. 49B, p. 1545, 1994; (5) Arepalli, Presser, Robie, and Gordon, "Detection of Cl Atoms and HCl molecules by Resonance-Enhanced Multiphoton Ionization," Chem. Phys. Lett., Vol. 118, p. 88, 1985; and (6) Arepalli, Presser, Robie, and Gordon, "Detection of Br atoms by REMPI," Chem. Phys. Lett., Vol. 117, p. 64, 1985; all of which are incorporated herein by reference.
In the laser photofragmentation/fragment detection approach, the target molecule is photolyzed to produce characteristic fragments, such as atoms and small molecules which can be detected by multiphoton ionization (PF/MPI) or laser-induced fluorescence (PF/LIF) since they possess favorable combination of usually strong optical transitions and sharp, well-resolved spectral features. However, PF/MPI is susceptible to high background noise as well as a high degree of interference due to nonresonant multiphoton ionization. For LIF, laser scatter can present a significant problem. Moreover, the collection of total LIF from the photofragment is difficult since it is isotropic and incoherent.

Detector of halogenated compounds based on laser photofragmentation/fragment stimulated emission

The United States of America as represented by the Secretary of The Army


A "DX" heat pump is provided herein which is based on the principle of providing optimal heat exchange in the heating mode through three parallel ground loops, two of which can be cut off from the system and evacuated of refrigerant in the cooling mode. The loops are designed in terms of volume so that the refrigerant charge is correct in the heating mode when split in three loops and also correct in the cooling mode when only one loop is used, but it contains the full system refrigerant charge.

(a) Field of the Invention
This invention relates to a geothermal heat pump for residential or commercial use falling under the general category of what is known in the industry as a "direct expansion" heat pump, (hereinafter referred to as a "DX" heat pump).
(b) Description of the Prior Art
Conventional technology concerned with heat pumps relies upon the transfer of heat from the ground by means of a secondary working fluid, e.g., water, which is pumped to the geothermal unit located in the heated structure. The conventional heat pump has its own internal heat exchanger which extracts the heat (heating mode) from this water, which is then pumped back to the earth to be reheated.
Such geothermal heat exchange is an efficient and effective way of achieving heat exchange in heating and air conditioning systems, and especially heat pump type systems. Since the ground temperature is relative constant at about 48.degree. F. at a depth below the frost line, the available heat is constant.
"DX" systems similarly use a ground coil system. However the working fluid is a refrigerant and the copper ground loop is the primary heat exchanger. A problem which has been associated with such systems is the means and manner in which the heat exchange coils, or outdoor coils, are placed into the ground to achieve geothermal heat exchange.
If the geothermal outdoor coils are placed into the ground in a vertical fashion, installation may be easily accomplished by drilling or boring holes into the ground, into which the vertical geothermal outdoor coils may be placed. The coils may quickly and easily be placed into the ground to a depth which is sufficient to overcome ground freezing problems associated with colder climates.
Heretofore, one reason why placing coils into the ground in a vertical fashion has not been workable was due to the fact that, when sufficient refrigerant was placed into the system to achieve maximum efficiency in both the heating and cooling cycles, the refrigerant, as it condensed in the ground coils, caused a liquid refrigerant build-up. The compressor was unable properly to move the refrigerant through the system when the liquid refrigerant settled within the ground coils, making the system unworkable. Damage to the compressor could occur when the compressor forced liquid refrigerant into the intake of the compressor, since compressors for such systems are designed for receiving and compressing gases.
Such problem associated with vertical outdoor geothermal coils was attempted to be solved by placing the coils into the ground in a horizontal fashion. Placing the coils into the ground in a horizontal fashion partially alleviated the problem of liquid refrigerant build-up. However, this technique required a vast amount of available ground to achieve the proper heat exchange, as well as the excavation of sufficient land to place enough ground coils to achieve sufficient heat exchange. In colder climates, this excavation must also be to a sufficient depth to place the coils for proper heat exchange. In short, placing the geothermal coils in a horizontal fashion was more difficult, expensive, and required much more available ground than does placing of the coils into vertical holes.
It has also been common practice to provide heat pump systems which included means for reversing the direction of flow of refrigerant from the compressor through two heat exchangers so that the functions of the heat exchangers were reversed. Thus, one of the heat exchangers was adapted to heat or cool the air of a room, for example, according to the direction of flow of refrigerant. When the direction of flow of refrigerant was reversed, it was necessary to alter the degree of restriction between the two heat exchangers to provide for proper operation of the system in the alternative function. Altering the degree of restriction relative to the direction of flow of refrigerant was necessary since a system optimized for cooling generally had insufficient restriction to provide optimum performance when operated to supply heat. That is, in a system optimized for cooling, the compressor normally circulated refrigerant through the evaporator faster than the surface could evaporate the refrigerant when the system was operated in the heating cycle. The compressor, in the heating cycle, then pumped unevaporated refrigerant and the system efficiency was low. To overcome this problem, variable restriction systems, using a "TX" or thermostatic expansion valve, have been employed in such heat pump systems. In many instances, two restrictors have been provided together with parallel valve systems, each of which was adapted to function in accordance with the direction of refrigerant flow.
A direct earth coupled heat pump was one that had its refrigerant evaporator/condenser in direct thermal contact with the earth from which heat was either extracted from in the heating mode or is introduced to in the cooling mode of operation. Many attempts have been made in the past to develop successful direct coupled heat pumps for residential and commercial uses. These attempts have failed adequately to meet a number of requirements associated with an economically and functionally viable system. Some of the shortcomings included: inadequate oil return to the compressor primarily in the heating mode; inadequate evaporator length and spacing for properly extracting heat from the earth resulting in low capacity and low efficiency of the systems; lack of a proper means to store additional refrigerant required during the cooling operation, but not needed during the heating mode; lack of volume control of the compressor for providing the necessary increase in displacement during the heating operation over that displacement needed for the cooling operation. This lack of displacement control resulted in insufficient heating capacity during the coldest weather.
U.S. Pat. No. 4,920,757 patented May 1, 1990 by J. Gazes et al attempted to provide a solution to overcome the problems associated with heat exchange with the outside air, water and geothermal means which have been employed for heat exchange. The patented solution was the provision of a geothermal heating and air conditioning system which included a compressor for compressing a refrigerant, and one or more indoor coils for heat exchange between the refrigerant and inside air. One or more outdoor coils were placed vertically below ground for heat exchange between the refrigerant and earth surrounding the outdoor coils. A condenser/receiver allowed the refrigerant to pass through the condenser/receiver in either direction, and was positioned between the indoor coil and the ground coils, allowing for heat exchange so as to control the state and temperature of the refrigerant. The condenser/receiver had sufficient volume capacity to accumulate liquid refrigerant to prevent liquid refrigerant from entering the compressor. A portion of the refrigerant travelling between the indoor coils and the outdoor coils was diverted to an inlet side of the compressor. A valve controlled a flow of refrigerant in response to refrigerant pressure on the inlet side of the compressor.
U.S. Pat. No. 5,038,580 patented Aug. 13, 1991 by D. P. Hart attempted to provide a solution to problems associated with heat pumps having direct earth coupled heat exchangers. The patented improvement provided a heat pump system having a sub-surface heat exchanger which used a heat exchanging fluid existing in gaseous and liquid form. The heat pump system included a compressor for compressing the heat exchanging fluid. A four-way reversing valve for directing the flow of the heat exchanging fluid was functionally connected to the compressor. An indoor heat exchange coil, functionally connected to the four-way reversing valve, was provided for transferring heat to or from the interior of a building. An accumulator, also functionally connected to the four-way reversing valve, was provided for trapping and storing liquids within the apparatus. A plurality of sub-surface tapered heat exchanger tubes were functionally connected to the four-way reversing valve. A bi-directional balanced expansion valve was functionally connected to the sub-surface heat exchanger. A receiver was provided for storing excess fluid functionally connected to the expansion valve and to the indoor heat exchange coil.
U.S. Pat. No. 4,327,560 patented May 4, 1982 by H. I. Leon et al, provided an earth-embedded heat pump system. That patent provided a system for transferring heat from the earth to a conditioned space wherein the heat transfer fluid was circulated in a substantially closed loop through an earth coil. Sections of the coil were jacketed with one or more hermetically-sealed enclosures which were adapted to be charged with a composition which, upon crystallization, released latent heat. The transition temperature at which the latent heat was released and the rate at which the latent heat was released to the heat transfer fluid was said to stabilize its temperature within a range which provided for an inlet condition to a water-to-air heat pump which was favourable to a high heat output from the heat pump system per unit energy input.
In U.S. Pat. No. 4,437,583 patented Mar. 8, 1983 by J. E. Downy, Jr., a complete system was disclosed for providing space heating and cooling, for an indoor living space which brought the heat from the geothermal storage capacity, (the earth), to the indoor living space during the heating season and extracted heat from the indoor living space and absorbed the heat into storage during the cooling season. In the patented system, a relatively massive thermal storage unit was interposed between the geothermal storage capacity, (the earth), and the indoor living space environment which was to be heated or cooled. A working fluid, e.g., water, was circulated between the massive thermal storage unit, and the geothermal storage capacity, (the earth). A heat pump was operatively connected between the massive thermal storage unit and the indoor living space environment. In addition, the working fluid, was circulated between heat exchangers, one of which was located in the massive thermal storage unit in contact with the working fluid therein and the second of which was located in the indoor living space environment.
U.S. Pat. No. 4,445,343 patented May 1, 1984 by W. J. McCarty provided a heat pump system comprising a compressor and two heat exchangers connected in a refrigerating circuit. Such refrigerating circuit was provided with refrigerant flow restricting means between the heat exchangers. Such restricting means imported relatively high restriction to the flow of refrigerant between the heat exchangers in one direction and a relatively lower restriction to the flow of refrigerant between the heat exchangers in the opposite direction.
U.S. Pat. No. 4,646,538 patented Mar. 3, 1987 by A. J. Blackshaw et al provided a heat pump system which had the capability of both space heating and cooling and which used the minimum number of components while at the same time permitting any two heat exchangers in the system to be used without involving the other heat exchanger so that any heat exchanger not being used in a particular mode could be bypassed. Further, those portions of the system not being utilized in any mode remained connected to the suction side of the compressor to depressurize that portion of the system. Liquid traps prevented the undesired build-up of refrigerant in that portion of the system not being currently used. The system design was said to permit the various operational modes by using only one additional externally controlled valve over that associated with a heat pump system used only to space heat and cool with the rest of the additional components used to interconnect the system being operated without any external control force.
The patented apparatus included a refrigerant pressurizing means whose high pressure outlet was connected to the input of a three-way valve. One output of the three-way valve was connected to the common input of a four-way valve. The common output of the four-way valve was connected to the suction side of the refrigerant pressurizing means. One of the reversible outlet ports on the four-way valve was connected to a space heat exchanger while the other reversible outlet port on the four-way valve was connected to a source heat exchanger. The opposite sides of the space and source heat exchangers were connected to each other through a reversible expansion device. The other output of the three-way valve was connected to an alternate heat exchanger. The other side of the alternate heat exchanger was connected to an alternate expansion device. The other side of the alternate expansion device was connected to the common point between the reversible expansion device and the space heat exchanger through a check valve allowing refrigerant to flow from the alternate heat exchanger to the space heat exchanger through a check valve. The other side of the alternate expansion device was also connected to the common point between the reversible expansion device and the source heat exchanger so that refrigerant could flow from the alternate heat exchanger to the source heat exchanger through a check valve.
As is evident from the above discussion, the general refrigeration cycle of a "DX" heat pump is similar to a conventional water-to-air or water-to-water heat pump in that it includes a compressor, an expansion device, a reversing valve, and a refrigerant-to-air heat exchanger. The unit functions as both a heating and cooling device and also generates domestic hot water. The "DX" heat pumps differ from conventional geothermal liquid source heat pumps in that the heat exchanger which transfers heat to and from the earth is an external part of the unit and is embedded directly in the earth in either a horizontal or vertical configuration. A "DX" machine takes the heat exchanger directly to the source of heat (the earth) while a conventional unit with a self-contained heat exchanger relies on having a fluid containing heat pumped to it for extraction. The heat pump and exchanger comprise one integral unit.


A guide system for injecting continuous conduit or tubing into a well under pressure including a closed pressurized chamber for equalizing the interior and exterior pressure on the conduit in the area where the conduit is under maximum stress due to bending or flexing. The chamber may be installed on a standard wellhead or injection head. Low friction guide sleeves are provided as a bearing surface for the conduit in the pressurized chamber.

1. Field of Invention
The subject invention is generally related to a system for injecting continuous flexible conduit or pipe into a well against the pressure of the well and is specifically directed to an apparatus and method for pressurizing the exterior wall of the conduit as it is flexed to enter the well.
2. Discussion of the Prior Art
Apparatus for feeding continuous tubing or conduit into a well are well known. An example of such a system is shown and described in U.S. Pat. No. 4,091,867, entitled: "Flexible Conduit Injection System", issued to F. E. Shannon et al, on May 30, 1978. As there shown, the well typically includes a Christmas tree above the opening with a blow-out preventer at the top or outermost opening. A connector is attached to the blow-out preventer for receiving and feeding the flexible conduit into and out of the well casing. The conduit is fed from a spool located at a distance from the well. As the conduit is paid out from the spool, it is flexed around a guide member to direct the conduit into the connector and into the well.
The conduit is typically under well pressure during this operation. At the area where the conduit is flexed around the guide path member the wall stresses are greatly increased, particularly due to the pressure difference between the internal and external walls of the conduit. This added stress greatly contributes to reducing the life of the conduit.
A number of different methods and systems for bending or flexing the conduit have been developed in order to minimize the pressure induced stress at the points of maximum flex. Most have attempted to resolve the problem by minimizing the amount of flex or bending to which the conduit is subjected. U.S. Pat. No. 3,920,076, entitled: "Method for Inserting Flexible Pipe into Wells", issued to T. Laky on Nov. 18, 1975 utilizes a rotating capstan to maintain a tangential support of the pipe as it enters the well.
The aforementioned U.S. Pat. No. 4,091,867 provides for a closed guide member in fluid communication with the connector at the blow-out preventer and an injector drive means to maintain the conduit exterior under well pressure during the injection or withdrawal function. Rollers are provided in the interior of the guide means to minimize friction as the conduit is fed therethrough. While this apparatus includes the advantage of reducing the differential pressure on the conduit, and thereby minimizing the wall stress particularly at points of maximum stress, the device disclosed in the '867 patent has not gained widespread acceptance. In order to provide the external pressure equalization of the conduit at the point of maximum flex, it is necessary to provide a closed pressure chamber from the spool injector head to the blow-out preventer connector. This has proven to be a cumbersome apparatus with the improved results not worth the effort. Further, the rollers provided in the curved guide member proved to be both complicated and somewhat unreliable, with a substantial number of moving parts required to be maintained in good working order while the conduit is moved through the system.
While the advantages of maintaining reduced differential pressure on the interior and exterior walls of the conduit are well recognized as a viable means for reducing fatigue in the highest stressed areas, a reliable functional means for achieving this has not previously been available.

Pressurized flexible conduit injection system


A method for driving a liquid display having at least two groups of common electrodes intersecting a respective two groups of segment electrodes to form a display dot at every intersection is provided. Each group of common electrodes is simultaneously sequentially scanned in order. A voltage is applied to display dots formed and at least one common electrode positioned on an end portion of each segment electrode which is different than the voltage applied to the common electrodes positioned at the remaining portions of the segment electrodes.

The present invention relates to a method for driving a liquid crystal display device, and in particular, to a method for driving a dot matrix liquid crystal display device.
Matrix liquid crystal displays are known in the art. Reference is made to FIGS. 1 through 3 in which a conventional matrix liquid crystal display is provided. A liquid crystal panel generally indicated as 1 is composed of a liquid crystal layer 5, a first substrate 2 and a second substrate 3 for sandwiching the liquid crystal layer 5 therebetween. A plurality of common electrodes Y1 through Y6 are oriented on substrate 2 in the horizontal direction and a plurality of segment electrodes X1 through X6 are formed on substrate 3 in substantially the vertical direction to form a matrix. Each intersection of common electrodes Y1 through Y6 and segment electrodes X1 through X6 forms a display dot 7. Display dots 7 marked by the hatching indicate an ON state, and the blank dots 7 indicate an OFF state. The dot structure of liquid crystal panel 1 is limited to a six by six matrix for simplicity however, in exemplary embodiments the number of dots of liquid crystal panel 1 may be much greater.
The voltage standard method is conventionally used for driving the prior art matrix liquid crystal display device. A selected voltage or non-selected voltage is sequentially applied to each of common electrodes Y1 through Y6. The period required to apply the successive selected voltage or non-selected voltage to all the common electrodes Y1 to Y6 is one frame.
Simultaneous to the successive application of the selected voltage or non-selected voltage to each common electrodes Y1 through Y6, an ON voltage or OFF voltage is applied to each segment electrode X1 through X6. Accordingly, to turn a display dot 7, the area in which one common electrode intersects one segment electrode, to the ON state, an ON voltage is applied to a desired segment electrode when the common electrode is selected by providing a selected voltage to the desired common electrode. Similarly if the display dot is turned OFF, the OFF voltage is applied to the desired segment electrode.
Reference is now also made to FIGS. 2 and 3 in which examples of the actual driving waveforms (waveform of the applied voltage) applied at the electrodes are provided. FIG. 2A shows the segment voltage waveform applied to segment electrode X5 over time. FIG. 2B shows the common electrode waveform applied to common electrode Y3 over time. FIG. 2C shows the voltage waveform applied for producing the ON state at display dot 8, the intersection of segment electrode X5 and common electrode Y3.
FIG. 3A shows the segment voltage waveform applied to segment electrode X5 over time. FIG. 3B shows the common voltage waveform applied to common electrode Y4 over time. FIG. 3C shows the voltage waveform applied to the display dot at the intersection of segment electrode X5 and common electrode Y4 to produce the OFF state.
In FIGS. 2 and 3, F1 and F2 indicate the frame period.
______________________________________ During frame period F1, selected voltage = V0, non-selected voltage = V4 ON voltage = V5, OFF voltage = V3 During frame period F2, selected voltage = V5, non-selected voltage = V1 ON voltage = V0, OFF voltage = V2, ______________________________________
wherein; EQU V0-V1=V1-V2=V EQU V3-V4=V4-V5=V EQU V0-V5=nV
(n is a constant).
Accordingly, by changing the polarity of the voltage which is applied to display dots 7 during frame periods F1 and F2, alternating driving is accomplished. It follows that whether the display dot 7 is ON or OFF depends on whether the ON voltage or OFF voltage is applied to the desired segment electrode when the selected voltage is applied to the intersecting common electrode corresponding to the desired display dot. This driving method is the voltage standard means used in the prior art.
The prior art structure and driving method has been less than satisfactory. When matrix liquid crystal display 1 is driven by the above conventional voltage standard method, the uniform rectangular waveforms illustrated in FIGS. 2 and 3 are not actually applied to display dots 7. Distortions in the applied waveforms occur. A first reason for the distortion is that each display dot 7 has an inherent electrical capacity based on the area of each dot 7, the thickness of the liquid crystal layers, the dielectric constant of the liquid crystal materials and so on. Secondly, both the common electrode and segment electrode are formed of a transparent conductive film having a surface resistance of about several tens of ohms as well as fixed electrical resistance. Therefore, even if the uniform rectangular waveforms as shown in FIGS. 2 and 3 are applied by the driving circuit, the waveform which is actually applied to the display dots becomes deformed and cross talk results. As a result, it becomes necessary to generate the difference of the effective voltage of the waveform which is applied to each display dot, resulting in the generation of contrast cross talk.
Observation has demonstrated that deformation of the voltage waveform being applied to the display dots occurs based upon relationship dependent on the pattern of the characters or drawings which is displayed by the liquid crystal display device. Secondly, the change of the effective voltage based on the deformation of the voltage waveform which is applied to the display dots causes the contrast crosstalk.
1. The first mode (zebra crosstalk)
Reference is now made to FIGS. 1, 4, 5, and 6A through 6C wherein zebra crosstalk is depicted. For simplicity of explanation, the common electrodes Y1 through Y6 are sequentially selected from the first common electrode Y1 to the sixth common electrode Y6, again returning to the first common electrode Y1. Additionally, liquid crystal panel 1 is a positive display wherein the greater the effective voltage applied to the display dots 7, the darker the display dot. A scale is provided in FIG. 4 to indicate relative darkness. This type of display is used for each explanation unless otherwise indicated.
If the display of FIG. 1 is desired and the inputs of FIGS. 2 and 3 are provided, the crosstalk of the display contrast as shown in FIG. 4 actually occurs in the liquid crystal display device 1. As can be seen, segment electrodes X1 through X4 receive identical inputs. The segment voltage waveform at the display dots portion of segment electrodes X1 through X4 is shown in FIG. 5A, the common voltage waveform applied at the display dot portion of the common electrode Y3 is shown in FIG. 5B. The voltage waveform applied at the display dots located at the intersections of segment electrodes X1 through X4 and common electrode Y3 is shown in FIG. 5C. The voltage waveforms applied to the four display dots will differ from each other slightly. However, this slight difference can be ignored here.
A spike shaped deformation of the voltage waveform occurs at the non-selected voltage level of the common voltage waveform as shown in FIG. 5B. The relationship between the direction and the size of the spike shaped voltage and the display pattern is as follows. Generally, when the selection of the successive common electrode moves from the nth common electrode to the (n+1)th common electrode, the number of segment electrodes to which the ON voltage is successively added is a, the number of segment electrodes to which the OFF voltage is successively applied is b, the number of segment electrodes to which a voltage is applied by switching from the ON voltage to OFF voltage is c and the number of segment electrodes to which the voltage is added by switching from the OFF voltage to ON voltage is d. The number of ON dots 7 on the nth common electrode is N.sub.ON. The number of OFF dots 7 on the nth common electrode is N.sub.OFF and the number of ON dots 7 on the (n+1)th common electrode is M.sub.ON while the number OFF dots on the (n+ 1)th common electrode is M.sub.OFF. The relationship between the segmented electrodes and common electrodes is as follows: ##EQU1##
K is a constant and equal to the total number display dots on each common electrode Y.
A value of I equal to the difference in ON dots between successive segment electrodes is defined as follows: ##EQU2## so, when the value of I is negative, the direction of the spike shaped voltage is in the direction of the ON voltage. On the other hand, where the value of I is positive, the direction of the spiked shaped voltage is in the direction of the OFF voltage. The size of the spike increases in accordance with the absolute value of I.
In other words, when the number d of segment electrodes in which the applied voltage switches from the OFF voltage to ON voltage is larger than the number c of segment electrodes in which the applied voltage switches from the ON voltages to OFF voltage, the spike shaped voltage occurs on the common voltage waveform in the direction of the ON voltage. In contrast thereto, when the sign of I, which is the difference between c and d, changes the spike shaped voltage occurs in the direction of the OFF voltage. Additionally, the value of the spike shaped voltage corresponds to the absolute value of I.
As shown in FIGS. 5A and 5B, when the relationship between the change of the segment voltage waveform and the direction of the spike shaped voltage of the common voltage waveform on the non-selected voltage are in-phase, a rounded corner occurs in the voltage waveform of the voltage applied at the display dots (FIG. 5C). The longer the in-phase period, the smaller the effective voltage value of the applied waveform, resulting in the displayed color becoming very light.
Reference is now made to FIG. 6 which illustrates the change of the segment voltage waveform and the direction of the spike on the common voltage waveform when the waveforms are out of phase. FIG. 6A shows the segment voltage waveform applied at the display dot portion of the segment electrode X5 of display 10. FIG. 6B shows the common voltage waveform applied at the display dot 7 portion of the common electrode Y3. FIG. 6C shows the combined voltage waveform which is applied to the display dot at the intersection of segment electrode X5 and common electrode Y3. As shown, where the relationship between the change in the segment voltage waveform (FIG. 6A) and the direction of the spike shaped voltage of the common voltage waveform of the non-selected voltage (FIG. 6B) are out of phase, a spike shaped voltage is generated in the combined voltage waveform applied to the display dots 7 (FIG. 6B), thereby increasing the effective value of the applied voltage. The longer the out of phase period, the larger the effective value, resulting in a darkening of the displayed color. Therefore, display dots 7 on segment electrodes X1 to X4 become light, and the display dots on the segment electrode X5 become dark regardless of the applied ON state or OFF state voltages. The darkness of display dots 7 on segment electrode X6 become a color of intermediate degree between the above on segment electrodes X1 to X4 and those on X5.
2. The second mode (horizontal crosstalk)
Reference is now made to FIGS. 7 through 10 in which a desired pattern is illustrated. FIG. 7 illustrates a display 11 on which a horizontal crosstalk pattern is displayed. Display 11 is the same as liquid crystal panel 1. The actual contrast crosstalk generated by display 11 is shown by display 12 of FIG. 8.
Display dot 7 acts as a capacitor. The capacity of this capacitor has a different value in the ON state than in the OFF state. The value of the capacitance in the ON state is larger than the capacitance in the OFF state. This occurs because the liquid crystal 5 acts as an anisotropic dielectric and the resulting alignment change occurs between the ON state and OFF state. Accordingly, the capacitance of all dots 7 on common electrode Y2 having many ON dots 13 is larger than that on common electrode Y4 having a few ON dots 13. Since common electrodes have the same circuit resistance, the rounded waveform generated in the voltage waveform of common electrode Y2 becomes larger.
FIG. 9A shows the segment voltage waveform over time applied at the display dot portion on the segment electrode X1 of display 11. FIG. 10B shows the common electrode waveform over time applied at the display dot portion on the common electrode Y2. FIG. 9C shows the combined voltage waveform over time applied to dot 7 at the intersection of segment electrode X1 and common electrode Y2.
FIG. 10A shows the segment voltage waveform over time applied at the display dot portion on the segment electrode X1 of display 11. FIG. 10B shows the common voltage waveform over time applied at the display dot portion on the common electrode Y4. FIG. 10C shows the combined voltage waveform over time which is applied to the dot at the intersection of segment electrode X1 and common electrode Y4.
As can be seen from a comparison of FIG. 9B and FIG. 10B, the waveform of common electrode Y2 which has many ON dots is more rounded when a change from the non-selected voltage to selected voltage occurs. This area is marked by the hatched area. As can be seen by comparing FIG. 9C with FIG. 10C the voltage effective value of the waveform which is applied to dots 13 on common electrode Y2 also decreases by the hatched area. Accordingly, the color produced at each display dot 7 of common electrode Y2 having many ON dots 13 becomes very light. Thus, if the number of ON dots on each common electrode is represented by Z, the larger the value of Z of the common electrode, the lighter the displayed color.
3. The third mode (vertical crosstalk)
Reference is now made to FIGS. 12 through 17C in which vertical crosstalk is illustrated. The pattern of display 14 is actually displayed a display 15 due to vertical crosstalk. the segment voltage waveform applied at the display dot portion on segment electrode X6 is shown in FIG. 13A. The common voltage waveform applied to the display dot portion on the common electrode Y2 is shown in FIG. 13B. The combined voltage waveform which is applied at the display dot at the intersection of segment electrode X6 and common electrode Y2 is shown in FIG. 13C. Further, FIGS. 14A through 14C show each voltage waveform on segment electrode X5 and common electrode Y2 and the voltage waveforms which are combined to form the actual waveform at the display dot at the intersection of segment electrode X5 and common electrode Y2.
A second example of vertical crosstalk is now described. The segment voltage waveform applied at the display dot portion of segment electrode X6 is shown in FIG. 17A. A desired pattern is input to produce the pattern on display 15. However, due to vertical crosstalk a pattern such as that of display 16 results. The common voltage waveform applied at the display dot portion of common electrode Y3 is shown in FIG. 17B. FIG. 17C shows the combined voltage waveform which is applied to the display dot at the intersection of segment electrode X6 and common electrode Y3. Similarly, FIGS. 18A through 18C show each voltage waveform applied at segment electrode X5, common electrode Y2 and the combined voltage waveform applied at display dot 7 at the intersection of segment electrode X5 and common electrode Y2.
The non-selected voltage level of the common voltage waveform during the displaying of the pattern of display 14 having many ON dots varies in the ON voltage direction as shown in FIG. 13B. Conversely, the non-selected voltage level of the common voltage waveform of display 15 having few ON dots varies in the OFF voltage direction as shown in FIG. 17B.
Where there are many ON dots, the variation is caused because each of common electrodes Y1 through Y6 is electrically connected to the segment electrode to which the ON voltage is applied through the condenser of display dots to a greater extent than to the segment electrode to which the OFF voltage is applied. The reason for this phenomenon is unclear, but it may occur due to a lack of sufficient output impedance of the power circuit relative to the load of the liquid crystal panel. The relationship for the generated voltage shift is described below.
For all display dots 7 of displays 14 and 15 T is the number of ON dots and L is the number of OFF dots. A value T' is defined as T'=T-L when T' is positive, the non-selected voltage level varies in the ON voltage direction. On the other hand, when T' is negative the non-selected voltage level varies in the OFF voltage direction. The size of the variation increases in accordance with the absolute value of T'.
Where the pattern includes many ON dots 13 as shown in display 14, the difference between the OFF voltage and the non-selected voltage becomes large and the difference between the ON voltage and the non-selected voltage becomes small. Therefore, comparing the voltage waveform (FIG. 14A) which is added to display dots 7 on segment electrode X5 of display 15 (FIG. 12) having no ON dot 13, with the voltage waveform FIG. 13A which is added to display dots 7 on segment electrode X6 having ON dot 13, illustrates that the effective combined voltage which is applied to display dot 7 on the segment electrode X5 is larger for the portion marked by the hatched area (FIG. 14C), thereby making the display dots on the segment electrode X5 dark when they should be blank.
Similarly, where the display has few ON dots 13 such as display 15, the difference between the ON voltage and the non-selected voltage becomes large, and the difference between the OFF voltage and the non-selected voltage becomes small. Therefore, comparing the voltage waveform which is provided to display dots 7 by segment electrode X6 including ON dot 13, and the voltage waveform which is provided to display dots 7 on the segment electrode X5 having no ON dot 13, the effective voltage which is provided to the display dots on the segment electrode X6 is larger than that of electrode X5 for the period marked by the hatched area (FIG. 17C) resulting in a dark display dot on segment electrode X6.
4. The fourth mode (inversion crosstalk)
Reference is made to FIGS. 18 through 21 in which inversion crosstalk is illustrated. A desired pattern is input to a display 17 (FIG. 19), but in reality appears as the pattern on a display 18 (FIG. 20) due to inversion crosstalk. FIG. 21A shows a segment voltage waveform provided at the display dot portion on segment electrode X6. FIG. 21B shows a common voltage waveform provided at the display dot portion on common electrode Y2. FIG. 21C shows a combined voltage waveform which is provided to display dot 7 at the intersection of segment electrode X6 and the common electrode Y2. FIG. 22 shows the combined voltage waveform provided to display dot 7 at the intersection of segment electrode X5 and common electrode Y2.
Reference is now made to FIGS. 23 through 26 wherein a second example of inversion crosstalk is provided. A pattern is input to appear as display 20 (FIG. 23), but in reality appears as the pattern of display 19 (FIG. 24) due to inversion crosstalk. FIG. 25A shows a segment voltage waveform provided at the display dot portion of segment electrode Y6. FIG. 25B shows a common voltage waveform provided at the display dot portion of common electrode Y2. FIG. 25C shows the combined voltage waveform which is provided at display dot 7 at the intersection of segment electrode X6 and common electrode Y2. FIG. 26 shows a combined voltage waveform provided by electrodes Y2 and X5 to display dot 7 at the intersection of segment electrode X5 and common electrode Y2.
The time period of switching between frame periods, i.e. before or after the switching from F1 to F2 of FIG. 21 and FIG. 25 is known as the inversion. As shown in FIG. 19 when the number of segment electrodes in which the voltage applied to the segment electrode is an ON voltage before and after the inversion (only the 6th segment electrode X6 in FIG. 19) is less than the number of segment electrodes in which the voltage applied to the segment electrode is an OFF voltage before and after the inversion (the five segment electrodes X1 to X5 in FIG. 19), a rounded waveform is as shown in FIG. 21B occurs at the time of inversion.
Therefore, when the pattern as shown in FIG. 19 is displayed, the rounded waveform occurs in the common voltage waveform as shown in FIG. 21B at the time of inversion.
Simultaneously, the voltage waveform applied to the segment electrode X6 (FIG. 21A) applied to display dots 7 on segment electrode X6 for changing from an ON voltage to an ON voltage before and after the inversion, generates a spike shaped voltage as shown in FIG. 21C, thereby increasing the effective voltage making the display dark. On the other hand, for the voltage waveform which is applied to display dots 7 of segment electrodes X1 through X5 for changing from an OFF voltage to an OFF voltage before and after the inversion, the rounded portion of the waveform as shown in FIG. 22 occurs, thereby decreasing the effective voltage, thus lightening the display.
Conversely in display 20 (FIG. 23) the spike shaped voltage is generated in the common voltage waveform as shown in FIG. 25B at the time of inversion. Simultaneously, when the applied waveform changes from an ON voltage to an OFF voltage before and after the inversion, a rounded section (FIG. 25C) is generated in the voltage waveform which is applied to display dots 7 on segment electrodes X1, X2, X3, X4 and X6, thereby decreasing the effective voltage and further lightening the displayed color. Additionally, when the voltage applied to the display dots on the segment electrode X5, switches from an OFF voltage to an OFF voltage before and after the inversion, a spike shaped voltage (FIG. 26) is generated thereby increasing the effective voltage, darkening the displayed color.
The above relationship is defined as follows. The number of segment electrodes switching from an ON voltage to an ON voltage at the time of inversion is a. The number of segment electrodes switching from an OFF voltage to an OFF voltage at the time of inversion is b. The number of segment electrodes for switching from an ON voltage to an OFF voltage is c. The number of segment electrodes for switching from an OFF to an ON voltage is d. Further, the number of ON dots on the common electrode (Y6, FIGS. 19 and 23) which is selected just before the inversion is NON and the number of OFF dots on the common electrode is NOFF while the number of ON dots on the common electrode (Y1, FIGS. 19 and 23) which is selected just after the inversion is M.sub.ON and the number of OFF dots on the common electrode is M.sub.OFF. ##EQU3## K is a constant representing the number of display dots on each common electrode. Wherein, ##EQU4## If the value of F is negative, at the time of the inversion, the rounded waveform occurs when the non-selected voltage changes on the common electrode. Conversely, if the value of F is positive, the spike shaped voltage occurs in the direction of the ON voltage. The value the applied voltage increases in accordance with the absolute value of F. This introduces the display crosstalk as mentioned above.
The general crosstalk problem has been well known in the art. A method for correcting crosstalk is also known in the art and is illustrated in Japanese Laid-open patent Nos. 31825/87, 19195/85 and 19196/85. The method consists of reversing the polarity of the voltage which is applied to the liquid crystal panel a predetermined number of times per frame. This method is known as the line reverse driving method.
However, this method has been less than satisfactory. The line reverse driving method corrects only one mode of crosstalk (zebra crosstalk) of the plurality of cross talkmodes. As mentioned above, there are four modes of crosstalk in the display relating to the mechanism which arise due to changes of the voltage waveform. Accordingly, the cross talk of the display contrast is not completely removed.
Another dot matrix display device known in the prior art has a plurality of groups of common electrodes as well as a respective plurality of groups of intersecting segment electrodes. As in the single electrode group embodiment discussed above, the common electrodes of each group are sequentially scanned and a voltage is applied at the intersections of the common electrodes and segment electrodes to form a display dot.
Reference is now made to FIG. 80 wherein an example of such a prior art matrix device, generally indicated as 700, having two groups of segment electrodes 706, 708 and two groups of common electrodes 702, 704 is provided. The common electrodes are positioned in order and are divided into two distinct groups the first group 702 including common electrodes Y.sub.1 through Y.sub.n and the second group of common electrodes 704 consisting of electrodes Y.sub.1 ' through Y.sub.n '. A plurality of segment electrodes is also divided into two groups, the first group 708 including segment electrodes X.sub.1 through X.sub.m and the second group of electrodes 706 including segment electrodes X.sub.1 ' through X.sub.m ' intersecting with the respective common electrodes of the first and second groups 702, 704. The common electrodes of each group are connected to each other in pairs of two so that each group is simultaneously sequentially scanned, i.e. common electrodes Y.sub.1 and Y.sub.1 ' are scanned simultaneously.
The prior art display matrix has been satisfactory. However, the display provided results in display dots on the common electrodes positioned on opposite ends of each segment electrode which differ in display density from display dots located intermediate the ends of the segment electrodes. For example, displayed dots formed on common electrodes Y.sub.2 through Y.sub.n-1 and common electrodes Y.sub.2 ' through Y.sub.n-1 ' which are positioned at intermediate portions of each segment electrodes X.sub.1 through X.sub.m and X.sub.1 ' through X.sub.m ', respectively have a uniform appearance of a substantially predetermined display density. However, a display dot formed on common electrode Y.sub.1 corresponding to an end portion of each segment electrode is less dense and a display dot formed on common electrode Y.sub.n is more dense. Similarly, a dot formed on common electrode Y.sub.1 ' is less dense than the intermediate display dots while a display dot formed on common electrode Y.sub.n ' is more dense. In particular, the display dots formed on common electrodes Y.sub.n and Y.sub.1 ' which are adjacent each other are strikingly uneven in density and therefor appear to have a large difference in shade thus appearing as a linear unevenness within the display.
The difference in display dot density at opposite ends of each segment electrode is generally caused due to capacitor type behavior within the display. The electrode intersections may be regarded as a capacitor having a predetermined capacity and display points along segment electrodes X.sub.1 and X.sub.1 ' may be defined as the equivalent circuit shown in FIG. 81. A display dot at an intersection of common electrodes Y.sub.1 and Y.sub.1 ' are denoted as d.sub.1 through d.sub.n and d.sub.1 ' through d.sub.n ' respectively. r and r' denote resistances along the segment electrodes X.sub.1 and X.sub.1 ' between adjacent common electrodes and have a value of several tens of .OMEGA. to several .OMEGA.. r.sub.1 and r.sub.1 ' denote resistances of the common electrodes between respective voltage supplies E and E' and the first segment electrodes X.sub.1 and X.sub.1 ' for respective common electrodes Y.sub.1 and Y.sub.n ' which have a value of several hundred .OMEGA. to several tens of K .OMEGA.. r.sub.2 and r.sub.2 ' correspond to the resistances of segment electrodes X.sub.1 and X.sub.1 ' between common electrodes Y.sub.1 through Y.sub.n and Y.sub.1 ' through Y.sub.n '. Generally, r.sub.2 and r.sub.2 ' may be represented as follows: EQU r.sub.2 =n.times. r EQU r.sub.2 '=n'.times. r'
Accordingly, EQU r.sub.1, r.sub.2 >> r EQU r.sub.1 ', r.sub.2 '>> r'
Assuming, that all display dots d.sub.1 through d.sub.n of segment electrode X.sub.1 and all display dots d.sub.1' through d.sub.n' of segment electrode X.sub.1' are illuminated regardless of the display pattern, and that common electrode Y.sub.1 is first selected, a selective voltage is applied to common electrode Y.sub.1 from voltage supply E and a voltage is input on display dot d.sub.1 through resistance r.sub.1 to form an illuminated display dot. Then, when common electrode Y.sub.1 is selected, common electrode Y.sub.2 is selected concurrently therewith and an illuminated voltage is input at segment electrode Y.sub.1. Selected voltages are then similarly applied on common electrodes Y.sub.3 through Y.sub.n and an illuminating voltage is applied to the segment electrode X.sub.1 corresponding to display dot d.sub.3 through d.sub.n. The selection process is again repeated in order beginning with common electrode Y.sub.1. Display dots d.sub.1 ' through d.sub.n ' on segment electrode Y.sub.1 ' are similarly illuminated.
When common electrode Y.sub.2 has been selected, as shown for example in FIG. 82, a charge C(n-1)V is discharged, where C represents the capacity of the display dot, V represents the difference between a non-selected voltage and a non-illuminating voltage and V represents a difference between the selected voltage and an illuminating voltage. However, the next scanning voltage applied at segment electrode X.sub.3 is concurrently selected, therefore, the charge is absorbed in the display d.sub.3. In such an occurrence, a charge flows through resistance r. However, since the resistance value is sufficiently small, the discharge and absorption are smoothly carried out, a distortion does not occur within the voltage waveform and the effective value remains unchanged. The common electrodes Y.sub.3 through Y.sub.m-1 are then sequentially selected in order. Accordingly, discharge and absorption of the charge are smoothly carried out through display dots d.sub.2 through d.sub.n-1 and the display density has a substantially predetermined uniform appearance. Display dots d.sub.2' through d.sub.n-1 ' of common electrode Y.sub.2 ' through Y.sub.n-1 ' are illuminated in a similar manner.
However, when common electrodes Y.sub.n and Y.sub.n ' have been selected and common electrodes Y.sub.1 and Y.sub.1 ' are next selected since the display dots d.sub.n+1 and d.sub.n+1 ' do not exist to follow after the display dots d.sub.n and d.sub.n ', the charge flowing from display dots d.sub.n and d.sub.n' must flow back to display dots d.sub.1 through resistances r.sub.2 and r.sub.2 '. However, resistances r.sub.2 and r.sub.2 ' are high enough that they can not be neglected and therefore the charge is not smoothly discharged and is rather stored at display dots d.sub.n and d.sub.n ' over a long period of time. As a result, the effective voltage becomes higher and the display density for display dot d.sub.n and d.sub.n ' becomes relatively high in comparison with the intermediate display dots.
On the other hand, when first display dots d.sub.1 and d.sub.1 ' are selected on common electrodes Y.sub.1 and Y.sub.1 ' no charge is absorbed from a previous display dot. Additionally, as described above when common electrodes Y.sub.1 and Y.sub.1 ' are selected after the selection of common electrodes Y.sub.n and Y.sub.n ' they do not absorb the charge from display dot d.sub.n and d.sub.n ' due to the high resistances r.sub.2 and r.sub.2 '. Accordingly, less of a charge is stored at display dots d.sub.1 and d.sub.1 ' providing a relatively less dense display.
Display dots d.sub.n and d.sub.1 ' of common electrode Y.sub.n and Y.sub.1 ' are disposed a distance from the voltage supply E and E'. Therefore, the shade unevenness becomes obvious. However, because charge and discharge are effected from the voltage supplied through respective resistances r.sub.1 and r.sub.1 ', the shade unevenness is minimized at display dot d.sub.1 and d.sub.n ' on common electrode Y.sub.1 and Y.sub.n '. Thus, density of display dot d.sub.1 and d.sub.n, d.sub.1 ' and d.sub.n ' on common electrodes Y.sub.1 and Y.sub.n, Y.sub.1 ' and Y.sub.n ' positioned at opposite ends of given segment electrodes X.sub.1 and X.sub.1 ' is different from that of other display dot d.sub.2 through d.sub.n-1 and d.sub.2 ' through d.sub.n-1 '. This also follows for the inverse electrode pairs Y.sub.1 and Y.sub.n and Y.sub.1 ' and Y.sub.n ' which are positioned at the end portions of the other segment electrodes X.sub.2 through X.sub.n and X.sub.2 ' through X.sub.n '. In particular, the density unevenness of display dots d.sub.n and d.sub.1 ' of common electrode Y.sub.n and Y.sub.1 ' of common electrodes Y.sub.1, and Y.sub.n and Y.sub.1 ' and Y.sub.n ' which are adjacent to each other becomes more obvious due to the shade difference and since it is usually positioned at the center of the display picture becomes even more noticeable.
Accordingly, a mechanism and method for driving a liquid crystal display which overcomes the limitations of the prior art is desired.

Circuit for driving a liquid crystal display device and method for driving same


A system for reconstruction of an explosion blast loading on a subject can include at least two pressure sensors and a computing system configured to: receive sensor data from the at least two pressure sensors, the sensor data being generated in response to an explosion blast wave; compute an explosion location and explosive charge mass of an explosive that caused the explosion blast wave based on the sensor data; and compute explosion blast loading on a subject from the explosion location and explosive charge mass. The pressure sensors can be configured as wearable pressure sensors or on equipment. The computing of the explosion location and explosive charge mass includes processing the sensor data through an inverse problem solver (IPS); and/or the computing of the explosion blast loading on the subject includes simulating the explosion blast wave with a forward problem solver (FPS).

Improvised explosive devices (IED) have become the common weapon used against military targets and in terrorism acts against civilian populations. Such devices can be deployed as road side bombs, vehicle mounted explosives, suicide vests and other forms, causing serious damage including loss of life [Homeland Department, 2018, Feldhoff, et. al., 1999]. The monitor report [Overton et. al., 2017] shows there were 7223 IED explosive incidents worldwide from year 2011 to 2016, which caused a total of 133,317 deaths and injuries (e.g., equal to 22,219 per year). Among all deaths and injuries civilian's deaths and injuries are 109,696 and armed actor's deaths and injuries are 23,621. The civilian casualty rate is 81% during this period.
Therefore, it would be advantageous to be able to identify the location and explosion charge mass of an IED event and can provide a great help for military (e.g., preparedness), law enforcement (e.g., investigations), protective gear manufacturers (e.g., design protective equipment), medical emergency personnel (e.g., emergency response), and general medical professionals (e.g., medical response to injuries).

System and method for reconstruction of explosion blast and blast loading on humans using pressure sensor data

The Government of the United States, as represented by the Secretary of the Army


A temperature compensated filter comprises a block (1) of dielectric material having at least one transmission line resonator (3) formed herein. All surfaces except one side surface of the block are substantially coated with an electrically conductive layer (11). For achieving temperature compensation, a capacitor (6) coupled to the conductive layer (11) through a strip line (7) is attached, in a heat conductive way, to the uncoated side surface of the dielectric block. The capacitor (6) tunes the main resonator and the temperature dependence of its frequency is opposite that of the dielectric body so that it compensates the temperature dependence of the frequency of the main resonator.

The present invention relates to a temperature compensated filter comprising a body of dielectric material having at least one transmission line resonator formed therein.
A dielectric filter is disclosed in European patent application EP-A-0,401,839 and corresponding U.S. Pat. No. 5,103,197, comprising a body of dielectric material which has upper and lower surfaces, two side surfaces, two end surfaces, and at least one hole extending from said upper surface towards said lower surface, an electrically conductive layer covering major portions of the lower surface, one side face, both end faces and the surface of said at least one hole so as to form said at least one transmission line resonator.
The properties required from the dielectric material are a high proportional dielectrical coefficient .epsilon.r and a small dissipation coefficient. The difficulty with this is that although materials with sufficiently high dielectric coefficients (about 8-100) and low temperature dependence, are available on the market they are relatively expensive and difficult to procure. Relatively good .epsilon.r values and a low temperature dependence of frequency can be obtained with ceramic compounds, for example, but the dissipation coefficients generally increase in these compounds.
The purpose of the present invention is to arrange, by using comparatively simple means, the temperature compensation of the frequency of a dielectric filter in which the material of the dielectric body can be chosen relatively freely on the basis of price and an advantageous dissipation coefficient.
According to the present invention a dielectric filter having the features mentioned in the opening paragraph above is characterized in that a capacitor is coupled to the transmission line resonator for tuning the filter and having a temperature coefficient of frequency opposite that of the dielectric body.
The capacitor itself forms part of the resonance circuit the frequency of which varies with temperature in the opposite sense to the frequency variation of the filter. Since the capacitor is coupled to the "main" transmission line resonator it has the effect of temperature compensating the filter.
Suitably, the filter may have a structure in accordance with that disclosed and claimed in the aforementioned European patent application and the corresponding US patent.
The capacitor may be a so-called chip capacitor which is attached to the dielectric body adjacent the hole therein, preferably on a side surface where the conductive layer is not present.
In a preferred embodiment the capacitor has one terminal electrically coupled to the electrically conductive layer, preferably through a conductive strip provided on the side surface of the dielectric body where the conductive layer is not present. The other terminal of the capacitor may also be coupled to a further conductive strip on the same side face.

Temperature compensated dielectric filter


The present invention provides adjuvants, vaccines and related methods that are useful in eliciting immune responses, particularly immune responses against tumor antigens. We discovered that flagellin is capable of inhibiting tolerance when it is administered in conjunction with a tolerogenic antigen. This effect is likely mediated by the ability of flagellin to induce IL-12 while keeping IL-10 levels low. Furthermore, flagellin can be provided in an extended-releasing manner by using a flagellin-expressing cell. Preferably, the flagellin-expressing cell is treated such that it is no longer capable of replicating, yet retaining the ability to express flagellin, such as by lethal irradiation.

The discovery of tumor specific antigens (neoantigens) that arise during tumor development inspired Burnet's immune surveillance theory. This theory states that the immune system is able to recognize and eliminate newly developing tumors based on the presence of neoantigens. However, since then many experiments have shown that immunocompromised individuals do not develop more malignancies than normal immunocompetent individuals, thus contradicting the idea that the immune system plays a protective role against the development of cancer. Therefore, it appears that tumors and their specific antigens do not provoke any immune response.
This phenomenon can be explained by the "two signal model of lymphocyte activation" of Brestcher and Cohn (Brestscher, P. and M. Cohn, A theory of self-nonself discrimination, Science (1970) 169(950):1042). This model states that for full activation of a T cell, two signals must be provided. Signal one comes from the recognition of a specific antigen through engagement of the T cell receptor, and signal two is provided by costimulatory molecules present on the antigen-presenting cell (APC). In the absence of costimulation, the T cell will not elicit an immune response against the antigen. Rather, it will assume a state known as anergy (Jenkins, M. K., and Schwartz R. H., Antigen presentation by chemically modified splenocytes induces antigen-specific T cell unresponsiveness in vitro and in vivo, J Exp Med (1987) 165(2): p. 302-319), which will be maintained even if the antigen is provided again.
APCs remain in a resting state in the absence of danger signals that indicate the presence of a pathogen and/or tissue damage. In the resting state, the APCs express low levels of costimulatory molecules and cytokines that would otherwise cause T cell activation. This mechanism is known as peripheral tolerance and avoids the production of harmful immune responses against self-antigens. Only when "danger" is associated with antigen presentation would APCs mature to an "activating state", leading to T cell priming. Recent studies suggest that although tumor antigens are presented by antigen presenting cells, the antigens are not effective in inducing maturation of the antigen presenting cells. As a result, the antigen presenting cells do not express sufficient costimulatory molecules, and the T cells engaged by such antigen presenting cells become tolerant to the antigen being presented.
Vaccination against cancer has been explored to eradicate tumor cells. In order for tumor cells to survive and proliferate, they must be able to avoid and/or overcome the immune system of the host. For example, induction of antigen specific CD4+ T cell tolerance is one of the mechanisms by which tumor cells overcome immune responses. Therefore, it is desirable to develop a vaccine that is capable of inhibiting tolerance or activating T cells that have escaped tolerance induction due to their low affinity for the tumor antigens.


A method and apparatus for aligning eccentricities in optical fibers arrayed in a fiber optic bundle is disclosed. The optical fibers are initially constrained from movement in a lateral or longitudinal direction. A light meter is used to detect the orientation of the eccentricity in the core of at least one optical fiber. The orientations of the optical fibers can be aligned such that all optical fiber cores have the same orientation relative to the fiber optic bundle.

1. Field of the Invention
The invention relates to optical fiber bundle technology and more particularly relates to aligning optical fibers.
2. Related Art
Optical fibers are considered a significant improvement over the information carrying capacity of metal wires. Optical fibers have greater bandwidth than metal wires i.e. they can transmit more data per unit time than a metal wire. According to current technology a single optical fiber has the capacity to carry 8.44 megabits per second (Mbps) of data.
Bandwidth can be increased by combining optical fibers together into bundles. For example, an Optical Carrier 1 (OC1) fiber optic bundle has a bandwidth of 51.84 megabits per second. Fiber optic bundles comprise, for example, up to 40 optical fibers in a single bundle, typically in the form of a ribbon cable where all the optical fibers are side to side in a row relative to each other. There are plans to place up to 128 optical fibers in a single fiber optic bundle.
Optical fibers have a central core through which the light carrying the data must travel. The central core must line up to whatever element it is desired to receive the information carried in the light traveling through that fiber. With single fibers it is difficult enough to align the core of the fiber and the receiver of the element to which the optical fiber is to deliver the information. The difficulty in aligning multiple optical fibers is multiplied by the number of additional optical fibers in the fiber optic bundle. Within an optical fiber, the core of the fiber can have an eccentricity removing the core from the center of the fiber by as much as one micron. Contributing to this misalignment as greater numbers of optical fibers are placed in fiber optic bundles is any warp inherent in the fiber optic bundle structure. Thus, alignment issues present a significant challenge in implementing optical fiber systems.

Eccentricity detect and alignment for fiberoptic bundle


Overlay measurement systems and methods are disclosed that control the relative phase between the scattered and specular components of light to amplify weak optical signals before detection. The systems and methods utilize model-based regressional image processing to determine overlay errors accurately even in the presence of inter-pattern interference.

Most fine structured devices such as integrated circuit chips, microelectromechanical devices, etc. are made of multiple layers of precisely aligned circuit or mechanical patterns. The patterns are usually formed through multiple high precision lithography steps during manufacturing where most patterns are required to be aligned precisely with respect to each other. However, even with best systems and efforts, some amount of lateral misalignment between different patterns is unavoidable. Overlay error is the lateral misalignment between different patterns or targets.
Traditionally, overlay error has referred to the alignment error between successive device layers, which will be called between-layer overlay error herein. However, in some cases such as double- or multi-patterning lithography, overlay error may refer to the lateral misalignment between different patterns in the same layer. This will be called single- or within-layer overlay error herein.
Currently, controlling overlay error is one of the most difficult tasks in semiconductor manufacturing because of the ever shrinking design rules and the complexity in modern manufacturing processes. Because overlay error can affect yield, device performance and reliability, it must be measured precisely. Overlay error can be measured in many different ways. However, in most cases, overlay error is measured optically by capturing the image of specially designed alignment marks called overlay targets and processing the image with a computer. Optical measurement is preferred because it is non-destructive and fast.
The overlay we are interested in is in the functional pattern areas. Unfortunately, optical overlay measurement systems can rarely measure the overlay of functional patterns directly because most of the functional patterns are too fine to be resolved by optical systems. Optical overlay measurement systems usually measure the overlay of functional patterns indirectly using a special non-functional pattern called an overlay target or simply a target. Overlay targets are usually made much coarser than the functional patterns in order to be resolved by optical systems. Optical overlay measurement systems measure the overlay error in the target area and make the assumption that the overlay error in the functional pattern area is the same or at least well correlated with the overlay error in the target area.
Because of the indirectness of the measurement, it is very important to have a good correlation between the two overlay measurements, the functional pattern overlay and the target overlay. In order to have a good correlation between the two overlays, we need to bind the overlay targets to the functional patterns tightly. Their tight binding is commonly achieved by including overlay targets as a part of the pattern design and by printing both the functional patterns and the targets at the same time. This kind of same time design and printing of both functional patterns and targets assures a good correlation between the overlay error measured in the functional pattern area and the overlay error measured in the target area.
When targets are printed, targets belonging to different process layers are printed in the same area on wafer in order to facilitate an accurate measurement of overlay errors. The imaging system takes a picture of all the individual targets in a single image. Thus, an overlay target viewed by an overlay measurement system is not a single target but a group of individual targets, which will be called a target set herein. Thus, a target set is different from an individual target. However, a target set will also be called a target herein whenever the context makes its meaning clear. The measured overlay error is the lateral offset or misalignment between different individual targets printed in the same area. In order to facilitate an accurate overlay measurement, the individual targets are usually printed with no or little overlap with each other even if they are placed in the same area. Thus, all individual targets are usually well distinguishable in the image. A target set usually contains two individual targets. However, it can contain more than two individual targets. In an example, the target area is 100 μm2 or less.
Currently, two optical technologies are being used for optical overlay measurement. One is an image-based technology and the other is a diffraction-based technology. Image-based technology takes an image of a target set and processes the image based on intensity slopes to determine the overlay error. Diffraction-based technology uses multiple targets each of which is made of two interleaving gratings. It does not resolve individual grating lines but measures the variation of diffraction efficiency caused by the offset variation between the interleaved gratings. The variation of offset between the two interleaved gratings is the overlay error that needs to be determined.
Diffraction-based overlay measurement systems were developed to achieve higher measurement accuracy than image-based systems. However, these systems have several drawbacks such as a requirement for multiple targets, inflexible target design, complicated system calibration, higher cost, etc. Especially, multiple diffraction targets require a relatively large clear area on the wafer to print all the targets. This makes this technology difficult to employ in many important applications such as in-die overlay measurement where large clear areas for target printing are not available.
The existing image-based overlay measurement systems are reliable and robust. However, they have many critical drawbacks such as requiring large targets, poor handling of weak overlay signals, shallow depth of focus, severe influence from patterns around the target and also from imaging system aberrations, etc. Therefore, the existing image-based overlay measurement systems are not suitable for the future applications most of which require small targets, good handling of weak signals, good filtering of detrimental interferences or influences, etc.

Phase-controlled model-based overlay measurement systems and methods


A programmable controller is disclosed for the purpose of controlling devices such as machine tools and other machinery, and which is often mated with a host computer numerical controller. The programmable controller is configured such that certain user-designated "fast-scan" outputs can operate at much higher speeds than non-designated "normal" outputs, thereby greatly increasing the response time and efficiency of the operations that are controlled by those fast-scan outputs. The programmable controller uses a processor which scans through its user-definable program (including the value of all system inputs and outputs) before it attempts to change the value of any of its outputs. The physical input/output (I/O) interfaces are located on I/O racks, each of which also includes an intelligent bus adaptor. The intelligent bus adaptor includes its own processor which periodically communicates with the processor in the programmable controller. The intelligent bus adaptor's processor controls the fast-scan outputs located on that particular I/O rack within very short time intervals, and allows for a response time that is an order of magnitude faster than the response time of normal outputs of the programmable controller.

Programmable logic controllers (PLC's, or programmable controllers) are common in industrial manufacturing facilities for control of various types of manufacturing equipment and plant or process equipment. Programmable controllers can be used as "stand-alone" controllers, in which the PLC itself is the primary control intelligence of the system, or can be used in cooperation with a more powerful computing or control system. In the machine tool industry, programmable controllers are often mated with a host computer numerical controller (CNC), which performs the calculation intensive tool path tasks that are necessary to properly control the associated machine tool in real time.
Programmable controllers typically contain a set of logical instructions within their user-definable program. Such instructions are user-changeable, and typically include instructions to determine the value of certain physical inputs, perform logical and numeric calculations based upon that information, perform certain time-dependent or count-dependent operations based on that information, and to determine the proper value of certain physical outputs which are controlled by the PLC. An example of an exemplary programmable controller known in the art is disclosed in U.S. Pat. No. 4,486,830 by Taylor, Jr. et al.
The user-definable program of a PLC must be periodically reviewed or "scanned" so that the value of internal variables that are associated with inputs can be determined and updated, and also so that the value of the associated outputs can be controlled, as required by the results of any mathematical or logical equations. In common PCL's, the user-definable program is scanned in a manner dictated by the results of the PLC's user-definable program. After the scan has been completed, the outputs of the PLC can be set to their proper values. Typically, PLC's do not communicate directly with the input and output equipment via address or data buses, but instead have special serial or parallel communication paths between the equipment installed in the input/output (I/O) racks which hold a bus adaptor, the physical input interfaces (which typically contain several physical inputs each), and physical output interfaces (which typically contain several physical outputs each). Only after a complete scan of the user-definable program has been completed do the PLC's attempt to change any output values by sending down messages to their associated I/O racks.
PLC systems available heretofore can only update their associated outputs with new information at a maximum rate of once per "scan" cycle of the PLC's user-definable program. The amount of time required to perform a complete scan of the user-definable program is dependent upon the scanning rate and the size of the user-definable program used in a given PLC. Typical times for such a single scan often fall within the range of 25 to 50 ms for the more complex applications that are used in controlling machine tools.
In a machine tool application wherein a host CNC is associated with a PLC, the PLC still works along the general lines described above, communicating with its inputs and outputs via communication paths to interfaces on I/O racks. In such systems, the CNC will perform the tool path calculations and the PLC will perform many, if not most, of the binary calculations. The PLC in such systems is the device that directly controls many of the physical binary outputs (two-state "on" or "off" outputs) used to control devices such as tool changer mechanisms and pallet shuttles, or the like. In smaller (less complex) systems, the PLC can perform all of the above calculations (both analog and binary), thereby eliminating the need for a host CNC.
Systems heretofore using PLC equipment have not been capable of controlling their outputs in response to certain changes in any of the associated inputs in less time than one scan cycle. Since an entire scan cycle of the user-definable program must be completed before the PLC could implement changes, the associated outputs could also only change value at the end of at least one of such scan cycles which did not commence until after the associated inputs which control those outputs have changed state. This timing limitation exists even in systems using CNC equipment, since as the CNC communicates with its associated PLC, the PLC must then scan the input portion of the input/output table of its user-definable program for changes of value in any of its equations (due to state changes in physical inputs, for example) before "deciding" that the PLC should change the value of any of its outputs. The CNC, operating as a host computer to the overall system, cannot force the PLC to perform its scanning cycle and its output updating routines in less time than the PLC is capable. In modern day applications requiring ever increasing speed and complexity, such limitations are a substantial roadblock to efficiency and increased production.

Fast programmable scan logic controller method and apparatus


Presented herein are systems, methods, and computer-readable media for recording event times in particle detection scenarios. The systems, methods, and computer-readable media involve the identification of one facility device as a grandmaster clock among at least two facility devices of a facility device set, where the respective facility devices are selected from a facility device type set including a beam monitor; a neutron instrument; a neutron chopper; a nuclear reactor; a particle accelerator; a network router; and a user workstation. The system, method, and computer-readable medium also involve configuring the facility devices to synchronize a clock component with the grandmaster clock; and, upon detecting an event, retrieve from the clock component of the selected facility device an absolute event timestamp that is independent of event times of other events, and store a record of the facility event and the absolute event timestamp in the data store.

Field of the Invention
The present disclosure is related to the tracking of events within the field of particle detection.
Discussion of the Prior Art
In a particle detector facility, devices may be configured to detect events such as the detection of particles and particle collisions within a collider. The devices may also be configured to interoperate with other devices to identify, with high precision, the occurrence time of the events. Many such facilities are configured to record the time of such events in a relative manner. For example, a periodic clock signal may be broadcast throughout the facility over a proprietary network. Respective devices may include a clock component that identifies the amount of time elapsed since the latest periodic clock signal, and, upon detecting an event, may retrieve and record the offset from the latest clock signal. The absolute time, sequence, and/or duration of the respective events may later be calculated by adding the time of the clock signal and the offset recorded for the event.

Time protocol based timing system for time-of-flight instruments