In a semitransparent liquid crystal display device comprising semitransparent layers having a projections and depressions structure including reflective portions and transparent portions, the transparent portions are formed so as to include nearly flat regions of the projections and depressions structure.

The present invention relates to a semitransparent liquid crystal display device with high intensity and low power consumption.
With the widespread use of mobile terminals and other similar equipment, the reflective liquid crystal panel has been drawn attention. This type of panel reflecting outer light for display shows sufficient display performance in bright conditions like outdoors; however, its visibility remarkably decreases in dark conditions.
In order to overcome this problem, a semitransparent liquid crystal panel capable of being used both indoors and outdoors has been developed by applying the technique of the reflective liquid crystal panel. In such a semitransparent liquid crystal panel, when a backlight is employed, each transparent portion in the form of a square is arranged at the center of a pixel in reflective layers which have a projections and depressions structure. In order to simplify manufacturing requirements, the projections and depressions structure is identical in all pixels (Refer to Japanese Laid-open Patent Application No. 10-319422).
However, in the case where such a large transparent portion is provided at the center of each pixel in the reflective layers, as in the above prior art case, the large total area of the transparent portions are irrelevant to reflection; intensity is insufficient when the panel is used as reflective type. As another problem, since the intensity in the reflective type is determined by the area of the transparent portions, providing transparent portions without regard to the projections and depressions structure makes reflectivity during reflection and permeability during permeation incompatible.
If the color filter layer has the same degree of thickness during permeation and during reflection, there is a problem that light has different degrees of absorption between during reflection and during permeation, thereby making color phases differ between during reflection and during permeation. The reason for this is considered that during reflection, light goes through the color filter layer and then returns through it, substantially making the color filter layer twice as thick as it is during permeation. As a result, for example, when a color filter for reflection with high permeability is used by giving reflectivity priority, there is a problem that the color is lightened during permeation
Further the pixels having the same projections and depressions structure also have the same capacity within the screen. Therefore, when the screen is larger, there is a problem that a decrease in gate voltage due to the line resistance of the gate and the source makes the punch-through voltage show different values within the screen, thereby causing flicker.
In order to solve the above-described problems, the inventors of the present invention have achieved a semitransparent liquid crystal display device with backlighting comprising semitransparent reflective layers having a projections and depressions structure as follows.
A first aspect of the invention is a semitransparent liquid crystal display device comprising semitransparent layers having a projections and depressions structure including reflective portions and transparent portions, wherein said transparent portions are so formed as to include nearly flat regions of said projections and depressions structure.
The nearly flat regions (regions of extremely small angles of inclination) in the projections and depressions structure do not contribute to an increase in panel reflectivity, and what is worse, deteriorate display performance because they cause specular reflection. Therefore, by so forming transparent portions as to include the nearly flat regions of the projections and depressions structure, the specular reflection can be prevented. In addition, the presence of the transparent portions can improve the permeability of light emitted from the backlight. The specific effects of the transparent portions will be described in the effects for a second aspect of the invention.
A second aspect of the invention is characterized in the first aspect of the invention, wherein the projections and depressions structure in the nearly flat regions has the angle of inclination of not less than 0 degree nor more than 2 degrees.
The reflection performance of the semitransparent layers having the projections and depressions structure is determined by the angle of inclination of the projections and depressions structure in the reflective portions. In order to efficiently gather ambient light in the viewer""s direction, it is necessary to arrange the angle of inclination of 2 to 10 degrees degrees in a specific distribution. Asperities having the angle of inclination of less than 2 degrees are likely to cause specular reflection and are not effective in light-gathering. The specular reflection causes degradation reverse, which remarkably lowers visibility. Thus, regions having the angle of inclination less than 2 degrees do not contribute to an increase in the panel reflectivity, and what is worse, may deteriorate the display performance due to the specular reflection. For this reason, in prior art devices, the reflective layers have been so arranged as not to create regions with small angles of inclination. However, the inventors of the present inventions have found that in a semitransparent display with backlighting, devoting the regions with small angles of inclination to transparent portions not only prevents the occurrence of specular reflection but also improves the panel reflectivity.
The specific effects of the present invention will be described as follows in comparison with a prior art device.
FIGS. 1 and 2 respectively show the top view and a cross sectional view of the array substrate of the liquid crystal panel in the prior art semitransparent liquid crystal display device. In the prior art device, the projections and depressions structure 204 is made from a resist in such a manner that as small flat regions as possible are created so as to prevent the reflective layers 202 from having small angles of inclination. However, no manner how the structure 204 is arranged, the peaks of the projective portions must be nearly flat, so that the reflective layers 202 are formed even in the nearly flat regions. On the other hand, since a large transparent portion 205 not provided with the reflective layers 202 is arranged at the center of a pixel so as to realize the semitransparent type, the projections and depressions structure 204 in the transparent portion 205 does not contribute to an increase in the reflectivity at all.
FIG. 3(a) shows an example of light trails on the reflective layers of the prior art semitransparent liquid crystal display panel. Light 210 reflected on an inclined surface in the projections and depressions structure 204 contributes to an increase in intensity, while light 211 regularly reflected near the peak of a projective portion is one cause of degradation reverse. Furthermore, the inclined surfaces of the projective portions in the transparent portions 213 are provided with transparent electrodes 214 only so that transparent light 215 can be generated without regard to the projections and depressions structure 204. Therefore, the inclined surfaces of the projective portions in the transparent portion 213 do not contribute to an increase in the panel reflectivity at all.
In contrast, the semitransparent liquid crystal display device of the present invention devotes the nearly flat regions of the projections and depressions structure in the reflective layers to transparent portions, which prevents a decrease in panel reflectivity and improves intensity during permeation. Thus devoting the regions not contributing to an increase in the panel reflectivity to transparent portions, both the reflectivity and the permeability can be improved.
FIG. 3(b) shows an example of light trails on the reflective layers of a semitransparent liquid crystal display panel of the present invention. Each transparent portion 301 having a transparent electrode 300 is formed near the peak of a projective portion. Light 302 reflected on an inclined surface which contributes to an increase in reflection performance is generated on the entire surface of the pixel, thereby improving the panel reflectivity. Furthermore, devoting the regions near the peaks of the projective portions which would cause degradation reverse in the prior art structure to the transparent portions 301 reduces the occurrence of gradation reverse and also secures the permeability of the backlight. These effects result from the fact that the panel permeability is determined by the total area of the transparent portions 301.
A third aspect of the invention is characterized in the first aspect of the invention, wherein the projections and depressions structure in the nearly flat regions has the angle of inclination of not less than 0 degree nor more than 4 degrees.
When the regions having the angle of inclination not more than 4 degrees are defined as nearly flat regions, the reflectivity decreases near the regular reflection direction, while the reflectivity in the visibility direction away from the regular reflection direction remains the same, thereby further improving the permeability.
A fourth aspect of the invention is characterized in the first aspect of the invention, wherein at least some of the transparent portions do not have transparent electrodes.
When the transparent portions are small in area, even if they do not have transparent electrodes, the electric field response of the liquid crystal on the transparent portions becomes possible in the electric field between the ambient reflective layers and the counter layers. Consequently the same effects as above can be obtained.
A fifth aspect of the invention is characterized in the first aspect of the invention, wherein the transparent portions have transparent electrodes.
As stated above, this is because if the transparent portions have a small area, transparent electrodes are dispensable; however, if they have a large area, it is preferable that they have transparent electrodes.
A sixth aspect of the invention is a semitransparent liquid crystal display device comprising semitransparent layers having a projections and depressions structure including reflective portions and transparent portions, wherein said transparent portions are so formed as to at least partly include projective portions of said projections and depressions structure.
Since the projective portions include nearly flat regions, areas including the nearly flat regions can be devoted to transparent portions so as to obtain the same effects as those of the first aspect of the invention.
A seventh aspect of the invention is characterized in the sixth aspect of the invention, wherein the transparent portions include peaks of the projective portions and are formed symmetric with respect to the peaks.
When the transparent portions are formed in the areas including at least the peaks of the projective portions of the projections and depressions structure, the peaks of the projective portions are the nearly flat regions of the projections and depressions structure, which can prevent a decrease in panel reflectivity and improve intensity during permeation. In other words, the devotion of the areas not contributing to an increase in the panel reflectivity like the peaks in the projective portions to the transparent portions can improve both the reflectivity and the permeability.
A eighth aspect of the invention is characterized in the sixth aspect of the invention, wherein the transparent portions include peaks of the projective portions and are formed asymmetric with respect to the peaks.
A ninth aspect of the invention is characterized in the sixth aspect of the invention, wherein the transparent portions are formed on half surfaces of the projective portions.
When the transparent portions are provided on the half surfaces of the projective portions to be more specific, when the transparent portions are mainly provided on the half surfaces of the projective portions on the viewer""s side and the reflective layers are provided on the other half surfaces, even if outer light is reflected by the viewer""s body and goes into the panel from the viewer""s side, the light is discharged through a transparent portion out to the rear side. As a result, mirroring is decreased and visibility is improved.
A tenth aspect of the invention is characterized in the sixth aspect of the invention, wherein a cross section of the projective portions has an asymmetrical figure comprising a plurality of inclined surfaces, and the transparent portions are formed on steeply-inclined surfaces of the asymmetrical figure.
When the steeply-inclined surfaces are arranged on the viewer""s side, light from the backlight goes diagonally from the transparent portions on the projective portions, which improves the intensity during permeation. Since approximately the entire surface becomes the reflective layers when seen from above, there is another effect of improving the reflectivity.
An eleventh aspect of the invention is a semitransparent liquid crystal display device comprising semitransparent layers having a projections and depressions structure including reflective portions and transparent portions, wherein a cross section of the projective portions of the projections and depressions structure is trapezoids, and the transparent portions are so formed as to at least partly include the top surfaces of the trapezoids.
Since the top surfaces of the trapezoids are nearly flat, the transparent portions can be so formed as to partly include the nearly flat top surfaces, thereby obtaining the same effects as above.
A twelfth aspect of the invention is characterized in the eleventh aspect of the invention, wherein the top surfaces of the projective portions are polygonal.
By making the top surfaces of the projective portions polygonal, the bearing angle of the inclined surfaces can be set freely, facilitating the adjustment of the visual angle.
A thirteenth aspect of the invention is a semitransparent liquid crystal display device comprising semitransparent layers having a projections and depressions structure including reflective portions and transparent portions, wherein the transparent portions are so formed as to include at least the bottoms of depressive portions of the projections and depressions structure.
A fourteenth aspect of the invention is characterized in the thirteenth aspect of the invention, wherein the depressive portions of the projections and depressions structure have bottoms, and the bottoms are nearly flat.
If the transparent portions are so formed as to include at least the nearly flat regions of the depressive portions, the nearly flat regions of the depressive portions do not contribute to the panel reflectivity, which makes it possible to improve both the panel reflectivity and the permeability. This will be described more specifically with reference to FIG. 4. FIG. 4 shows the light trails on the reflective layers of another semitransparent liquid crystal panel of the present invention. Regions 401 between projective portions 400 can be made nearly flat and be used as transparent portions so as to improve both reflectivity and permeability.
A fifteenth aspect of the invention is characterized in the thirteenth aspect of the invention, wherein the reflective portions are formed asymmetric with respect to the peaks of the projective portions.
A sixteenth aspect of the invention is characterized in the fifteenth aspect of the invention, wherein the reflective portions are formed on half surfaces of the projective portions.
As shown in FIGS. 5(a) and 5(b), when the reflective portions are provided asymmetric with respect to the peaks of the projective portions, the outer light can be gathered effectively in the viewer""s direction by the same principle as stated above. When the reflective portions 410 are provided more in the side opposite to the viewer""s side in the projective portions as shown in FIG. 5(a), the outer light coming from the side opposite to the viewer""s side can be collectively gathered. On the other hand, when the reflective portions 410 are provided more in the viewer""s side as shown in FIG. 5(b), the outer light reflected by the viewer""s body or coming from the back of the viewer can be collectively gathered. When the patterns of FIGS. 5(a) and 5(b) are mixed in an appropriate ratio, their respective light-gathering properties can be averaged in accordance with the mixture ratio, thereby adjusting the light-gathering properties more effectively.
A seventeenth aspect of the invention is a semitransparent liquid crystal display device comprising semitransparent layers having a projections and depressions structure including reflective portions and transparent portions, wherein the transparent portions are formed at least in regions including the peaks of the projective portions and in regions including the bottoms of the depressive portions.
In this structure, both the reflectivity and the permeability can be further improved.
A eighteenth aspect of the invention is characterized in the seventeenth aspect of the invention, wherein both the peaks of the projective portions and the regions including the bottoms of the depressive portions are nearly flat.
A nineteenth aspect of the invention is characterized in the eighth aspect of the invention, wherein the transparent portions are formed separately from each other.
A twentieth aspect of the invention is characterized in the eleventh aspect of the invention, wherein the transparent portions are formed separately from each other.
A twenty-first aspect of the invention is characterized in the nineteenth aspect of the invention, wherein the transparent portions are arranged at random.
A twenty-second aspect of the invention is characterized in the twentieth aspect of the invention, wherein the transparent portions are arranged at random.
Thus arranging the transparent portions at random realizes a panel without having diffraction, coloring, or inconsistencies in intensity.
A twenty-third aspect of the invention is characterized in the thirteenth aspect of the invention, wherein the transparent portions are partly connected with each other.
A twenty-fourth aspect of the invention is characterized in the seventeenth aspect of the invention, wherein the transparent portions are partly connected with each other.
A twenty-fifth aspect of the invention is characterized in the thirteenth aspect of the invention, wherein the reflective portions are partly connected with each other.
A twenty-sixth aspect of the invention is characterized in the seventeenth aspect of the invention, wherein the reflective portions are partly connected with each other.
When the reflective portions are made from conductive material, connecting the reflective portions partly with each other facilitates the electric connection in the contact hole.
A twenty-seventh aspect of the invention is characterized in the thirteenth aspect of the invention, wherein a color filter layer is formed on the projections and depressions structure, and the color filter layer has a thickness of d1 on the projective portions and a thickness of d2 on the depressive portions, the thickness d2 being greater than the thickness d1.
A twenty-eighth aspect of the invention is characterized in the seventeenth aspect of the invention, wherein a color filter layer is formed on the projections and depressions structure, and the color filter layer has a thickness of d1 on the projective portions and a thickness of d2 on the depressive portions, the thickness d2 being greater than the thickness d1.
Light entering as outer light and reflected by the reflective layers permeates through the portions of the color filter layer that have a thickness of d1. The outer light permeates through the color filter layer before reaching the reflective layers, and again permeates through the color filter layer after being reflected by the reflective layers in other words, the outer light permeates through the color filter layer of the thickness d1 twice. On the other hand, transparent light emitted from the backlight through the depressive portions permeates through the color filter layer of the thickness d2 only once. Consequently, even if a color filer layer for reflection with high permeability is used, the transparent light from the backlight passes through the portions of the color filter layer that have a larger degree of thickness, so that enough color reproducibility can be obtained in the case of transparent light.
A twenty-ninth aspect of the invention is characterized in the twenty-seventh aspect of the invention, wherein the thickness d2 is approximately two times larger than the thickness d1.
A thirtieth aspect of the invention is characterized in the twenty-eighth aspect of the invention, wherein the thickness d2 is approximately two times larger than the thickness d1.
In the above structure, the transparent light from the backlight and the outer light have an equal distance to pass through the color filter layer, so that the obtained color reproducibility is approximately equal during permeation and during reflection.
A thirty-first aspect of the invention is a semitransparent liquid crystal display device comprising semitransparent layers having a projections and depressions structure, the semitransparent layers partly overlaying a gate line on a substrate, wherein capacitance in an overlaid area of the semitransparent layers with the gate line decreases with increasing distance from a gate writing side of a liquid crystal panel.
A thirty-second aspect of the invention is characterized in the thirty-first aspect of the invention, wherein an average degree of thickness of said overlaid area increases with increasing distance from the gate writing side of said liquid crystal panel.
A thirty-third aspect of the invention is characterized in the thirty-second aspect of the invention, wherein an area ratio of the projective portions to the depressive portions in the overlaid area increases with increasing distance from the gate line side of the liquid crystal panel.
A thirty-fourth aspect of the invention is a semitransparent liquid crystal display device comprising semitransparent layers having a projections and depressions structure, the semitransparent layers partly overlaying a source line on a substrate, wherein capacitance in an overlaid area of the semitransparent layers and the source line decreases with increasing distance from a gate writing side of a liquid crystal panel.
A thirty-fifth aspect of the invention is characterized in the thirty-fourth aspect of the invention, wherein an average degree of thickness of the overlaid area increases with increasing distance from the gate writing side of the liquid crystal panel.
A thirty-sixth aspect of the invention is characterized in the twenty-fifth aspect of the invention, wherein an area ratio of the projective portions to the depressive portions in the overlaid area increases with increasing distance from the gate line side of the liquid crystal panel.
A thirty-seventh aspect of the invention is characterized in the thirty-first aspect of the invention, wherein the capacitance changes continuously.
A thirty-eighth aspect of the invention is characterized in the thirty-fourth aspect of the invention, wherein the capacitance changes continuously.
The effects of the thirty-first to the thirty-eighth aspects of the invention will be described as follows.
During the panel is being operated, the gate voltage decreases due to the line resistance of the gate as it gets far from the writing side. As a result, when the pixels have a uniform capacity within the screen, flicker occurs after writing. The counter potential Vcom necessary to eliminate the flicker differs within the screen. Difference xcex94Vcom in counter potential at each position within the screen, as compared with the counter potential Vcom on the line side is expressed in Formula (1) below.
xcex94Vcom=[(Cst+Cgd+Csd)/Clc]xc3x97xcex94Vgxe2x80x83xe2x80x83(1)
Cst: storage capacity
Cgd: gate-drain capacity
Csd: source-drain capacity
Clc: liquid crystal capacity
xcex94Vg: difference in gate voltage at each position within the screen, as compared with the initial value of the gate voltage on the line side
In order to reduce flicker, it is necessary to maintain xcex94Vcom below a fixed value, even if xcex94Vg continuously increases with increasing distance from the writing side. Therefore, it is necessary to reduce all or either one of Cst, Cgd, and Csd in accordance with an increase in xcex94Vg.
The parasitic capacity due to the projections and depressions structure formed in the overlaid area of the gate line with the reflective layers is included in Cst in terms of an equivalent circuit. Consequently, the parasitic capacity due to the projections and depressions structure formed in the overlaid area of the gate line with the reflective layers with increasing distance from the writing side can be decreased, so as to obtain the effect of reducing flicker. The degree of a decrease in potential due to the resistance of the gate line continuously increases in accordance with the distance from the writing side, provided that the lines have a uniform width. As a result, continuously changing the parasitic capacity can reduce flicker further effectively.
The parasitic capacity can be changed by the average degree of thickness of the projections and depressions structure formed in the overlaid area of the gate line with the reflective layers. The average degree of thickness is defined by the value obtained by dividing the volume of the overlaid area by the bottom space of the overlaid area. Alternatively, the parasitic capacity can be changed by varying the area ratio of the projective portions to the depressive portions. This can be done because the average degree of thickness increases when the projective portions are larger in area than the depressive portions, and decreases when the depressive portions are larger in area.
Generally, when nearly flat reflective layers are used, the space of the overlaid area is changed, and the degree of thickness is fixed so as to continuously change the value of the parasitic capacity for each pixel. This is because it is difficult to change the degree of the thickness of the layers which is determined by how it is deposited from pixel to pixel. However, by using the layers having the projections and depressions structure, the value of the parasitic capacity is easily changed by the ratio of the projective portions to the depressive portions, even if the resist is deposited with a uniform degree of thickness. On the other hand, in a semitransparent panel with the projections and depressions structure, if the parasitic capacity is changed by the space of the overlaid area, regions without the projections and depressions structure are expanded, which decreases intensity and causes its variations within the screen, thereby degrading the display quality. However, by changing the parasitic capacity by varying the ratio of the projective portions to the depressive portions, the projections and depressions structure can be formed on the entire surface, eliminating the occurrence of problems such as an intensity decrease. Consequently, in a semitransparent panel comprising semitransparent layers having the projections and the depressions structure, the occurrence of flicker can be effectively prevented by changing the ratio of the projective portions to the depressive portions that is, average degree of thickness.
The parasitic capacity of the overlaid area of the reflective layers with the source line is included in Csd in Formula (1). Therefore, in the same principle as above, the occurrence of flicker can be reduced by decreasing the parasitic capacity due to the projections and depressions structure formed in the overlaid area of the source line with the reflective layers with increasing distance from the writing side. In this case, too, it is effective to change the parasitic capacity by the average degree of thickness of the projections and depressions structure.
A thirty-ninth aspect of the invention is a semitransparent liquid crystal display device comprising semitransparent layers having a projections and depressions structure including reflective portions and transparent portions, wherein the transparent portions are so formed as to include at least the peaks of projective portions of the projections and depressions structure, and micro lenses are arranged under the projective portions.
In this structure, light from the backlight is gathered by micro lenses and emitted through the transparent portions arranged at the peaks of the projective portions, thereby achieving high intensity during permeation
A fortieth aspect of the invention is a semitransparent liquid crystal display device comprising semitransparent layers having a projections and depressions structure including reflective portions and transparent portions, wherein pixels comprise the transparent portions of different area ratios.
In this liquid crystal display device, variations in intensity occur in accordance with the distance from the backlight. The intensity of the panel is likely to increase as it is closer to the backlight. Therefore, intensity within the screen can be uniformed by changing the area ratio of the transparent portions to the pixels according to the position within the screen. To be more specific, the area ratio of the transparent portions can be made smaller as they are closer to the backlight.
A forty-first aspect of the invention is characterized in the fortieth aspect of the invention, wherein the transparent portions have a range of area ratio where panel reflectivity is approximately constant.
When the transparent portions are arranged in the nearly flat regions in the projections and depressions structure, the regions do not contribute to an increase in panel reflectivity, so that the panel reflectivity becomes approximately constant without regard to the area ratio of the transparent portions. Therefore, the intensity within the panel screen can be uniformed both during permeation and during reflection.
A forty-second aspect of the invention is a semitransparent liquid crystal display device comprising semitransparent layers having a projections and depressions structure including reflective portions and transparent portions, wherein the transparent portions are formed in regions where the projections and depressions structure has the angle of inclination of not less than 10 degrees.
A forty-third aspect of the invention is a semitransparent liquid crystal display device comprising semitransparent layers having a projections and depressions structure including reflective portions and transparent portions, wherein the transparent portions are formed in regions where the projections and depressions structure has the angle of inclination of not less than 10 degrees and in regions where the projections and depressions structure has the angle of inclination of not more than 2 degrees.
The distribution of the angles of inclination of the projections and depressions structure has a strong correlation with the reflection properties of the panel. For example, when light enters with the angle of 30 degrees and the reflected light is gathered in the polar angle of 0 to 25 degrees, the angle of inclination involved with light-gathering is in the range of about 2 to 10 degrees. The light reflected in the nearly flat regions of less than 2 degrees becomes light of regular reflection, which causes display defect. On the other hand, the light reflected in regions having a large angle of inclination of not less than 10 degrees is either reflected to the side opposite to the direction of visibility or enclosed inside the panel without being involved with light-gathering. Consequently, as stated above, even if the regions with the angle of inclination of not less than 10 degrees are included in the transparent portions in addition to the nearly flat regions, the reflection properties within the visible range remain the same. Furthermore, the intensity during permeation is improved by the expansion of the area of the transparent portions.

Semitransparent liquid crystal display device

Matsushita Electric Industrial Co., Ltd.


A digital-to-analog conversion system is provided. The digital-to-analog conversion system includes a digital-to-analog converter configured to receive a pre-distorted digital signal from a digital circuit, and to generate an analog signal based on the pre-distorted digital signal. Further, the digital-to-analog conversion system includes a feedback loop for providing a digital feedback signal to the digital circuit. The feedback loop includes an analog-to-digital converter configured to generate the digital feedback signal based on the analog signal, and wherein a sample rate of the analog-to-digital converter is lower than a sample rate of the digital-to-analog converter.

Digital PreDistortion (DPD) is a digital technique mainly known for improving the linearity of power amplifiers. Power amplifiers operate with better or more energy efficiency when a certain degree of nonlinearity is allowed—typically compression of the input signal (i.e. a smaller gain at higher amplitudes is allowed). The nonlinear input-output relationship changes the harmonic content of the signal. This causes, e.g., harmonic distortions (i.e. overtones that are multiples of the input signal frequencies) or inter-modulation distortions (i.e. additional signal components at frequencies that are the sum and difference of the frequencies of the original input signal components and at frequencies that are multiples of those sum and difference frequencies). These distortions may introduce interference in both adjacent and distant signal channels. With each new communication standard, the requirements regarding the maximum allowed interference in other radio channels are getting stricter.
Similarly, digital to analog converters (DAC) are also affected by nonlinearity (although the nonlinearity may be reduced as described above)—for example if the digital to analog converters are designed for low power consumption. In addition to the inherent nonlinearity of the digital to analog converter itself (e.g. due to the use of nonlinear elements such as transistors, see above), there are other effects that translate into nonlinear behavior. For example, a non-ideal power supply, an associated network, component mismatches or clock distribution skew.
DPD may be used to mitigate the digital to analog converter nonlinearity. For proper mitigation of the digital to analog converter nonlinearity, a trained DPD (e.g. a DPD algorithm) is needed.
Hence, there may be a desire for improved DPD training architectures.


A control circuit is described herein. The control circuit includes an oscillator and a processor. The oscillator is configured to generate a reference signal. The processor is coupled to the oscillator. The processor is configured to receive a first output current sample, a second output current sample, and a third output current sample, all of an output current. The first output current sample is first-in-time, the second output current sample is second-in-time, and the third output current sample is third-in-time. The processor is further configured to compute a time-derivative of the output current. The processor is further configured to compute a command variable based on the reference signal, a time-derivative of the reference signal, the third output current sample, and the time-derivative of the output current.

The present application relates generally to uninterruptible power supplies (UPSs), and more specifically, to a controller for an inverter circuit and a method of use thereof.
Modern power electronic systems, such as uninterruptible power supplies (UPSs), use switched converters coupled with LC filters to remove high-frequency components. The switched converters have an output impedance that represents the ability of the switched converter to maintain a target output voltage under varying load conditions. This is sometimes referred to as output dynamic stiffness. For example, in certain fields, the load varies non-linearly, as in a typical computer load. In other fields, such as medical imaging, the load pulses, in which case a higher output dynamic stiffness is preferred. For a given load, the output dynamic stiffness of an inverter can be characterized by a voltage total harmonic distortion (THD), which is expressed as a percentage. An ideal inverter has zero output impedance and a THD of 0%. The voltage THD is not an absolute measure of dynamic stiffness. Voltage THD allows a comparison of performance of various inverters for a same load, for example, the full non-linear load according to IEC 62040-3.
Output dynamic stiffness is typically a function of control strategy, modulation, DC-link voltage, and design of the inverter filter. In transformer-based UPS systems, the coupling of transformer windings is an additional factor.

System and method for controlling dynamic output impedance of an inverter


Phenoxyalkylcarboxylic acid derivatives of the following formula, ##STR1## wherein R.sup.1 indicates hydrogen atom, methyl group or ethyl group, m is an integer from 2 to 5, and n is an integer from 3 to 8, X.sup.1 and X.sup.2 each independently represent sulfur atom, oxygen atom, sulfinyl group or sulfonyl group, proviso X.sup.1 and X.sup.2 are not simultaneously oxygen atom; their alkali salts and hydrates thereof are useful as antiallergic agents.

1. Field of the Invention
This invention is concerned with certain novel phenoxyalkylcarboxylic acid derivatives which have strong and selective leukotriene antagonist activity, and are useful for prevention and treatment of allergic diseases such as bronchial asthma and so on, their intermediates and their preparation processes thereof.
Moreover, it relates to certain novel phenoxyalkylcarboxylic acid derivatives of the general formula (I), ##STR2## wherein R.sup.1 indicates hydrogen atom, methyl group or ethyl group, m is an integer from 2 to 5, and n is an integer from 3 to 8, X.sup.1 and X.sup.2 each independently represents sulfur atom, oxygen atom, sulfinyl group or sulfonyl group, proviso X.sup.1 and X.sup.2 are not simultaneously oxygen atom; their alkali salts and hydrates thereof.
2. Description of the Prior Art
Leukotrienes (leukotriene C.sub.4, D.sub.4, E.sub.4), which are metabolites of arachidonic acid through 5'-lipoxygenase pathway, are constituents of SRS-A (slow reacting substance of anaphylaxis), being an important mediator of the immediate type allergic diseases such as bronchial asthma. Accordingly, the drugs which exert antagonistic effects on leukotrienes are promising in the treatment of allergic diseases. But, only few drugs having those effects through the internal use are known and none is practically used.
Compounds having somewhat similar structure with those of the present invention are described in Japanese Patent Unexamined Publication (Kokai) Sho No. 58-189137 which corresponds to U.S. Pat. No. 4,507,498. These compounds can be characterized by the ether bond, but they never have thioether bond and thus, they are structurally different from the compounds of the present invention. Moreover, the compounds described in the art have been revealed to be less effective and are not useful as compared with the compounds of the present invention.
3. Detailed Description of the Invention
As the result of diligent studies about leukotriene antagonists, the inventors have found that the compounds represented by the general formula (I) possess strong and selective leukotriene antagonist activity even after an oral administration and further found that they have surprisingly therapeutic effects on airway hyperreactivity induced in guinea pigs, which lead to completion of the present invention.
According to the present invention, the compounds of the general formula (I) can be prepared on the hereinafter mentioned routes. (1) Compound of the general formula (Ia) can be prepared by allowing compounds of the general formula (II) to react with compounds of the general formula (III) ##STR3## (wherein R.sup.2 indicates methyl group or ethyl group, m is an integer from 2 to 5, n is an integer from 3 to 8, X.sup.1 indicates sulfur atom, oxygen atom, sulfinyl group or sulfonyl group, X.sup.3 indicates sulfur atom or oxygen atom, proviso X.sup.1 and X.sup.2 are not simultaneously oxygen atom) ##STR4## (wherein R.sup.2, n and X.sup.3 are as defined in the above) ##STR5## (wherein Y indicates halogen atom and X.sup.1 are as defined in the above)
It is preferable that this reaction is conducted in an organic solvent, for example acetone, methylethylketone, diethylketone or dimethylformamide etc. under a reaction temperature of the room temperature to the solvent refluxing temperature. In addition, the presence of an inorganic base, for example potassium carbonate or sodium carbonate etc. and further the addition of potassium iodide are also recommendable.
(2) Compounds represented by the general formula (Ib) can be prepared by allowing compounds of the general formula (IV) to react with compounds of formula (V). ##STR6## (wherein R.sup.2 indicates methyl group or ethyl group, m is an integer from 2 to 5, n is an integer from 3 to 8, X.sup.2 indicates sulfur atom, oxygen atom, sulfinyl group or sulfonyl group and X.sup.3 indicates sulfur atom or oxygen atom, proviso X.sup.2 and X.sup.3 are not simultaneously oxygen atom) ##STR7## (wherein Y.sup.1 indicates halogen atom, and R.sup.2, X.sup.2, m and n are as defined in the above) ##STR8## (wherein X.sup.3 is as defined in the above)
It is preferable that this reaction is conducted in an organic solvent, for example acetone, methylethylketone, diethylketone or dimethylformamide etc. under a reaction temperature of the room temperature to the solvent refluxing temperature. In addition, the presence of an inorganic base, for example potassium carbonate or sodium carbonate etc. and further the addition of potassium iodide are also recommendable.
(3) Compounds represented by the general formula (IIa) can be prepared by allowing compounds of the general formula (VI) to react with compounds of the general formula (VII), followed by removing the protective group. ##STR9## (wherein R.sup.2 indicates methyl group or ethyl group and n is an integer from 3 to 8) ##STR10## (wherein R.sup.3 indicates a protective group) EQU Y.sup.2 --(CH.sub.2).sub.n COOR.sup.2 (VII)
(wherein Y.sup.2 indicates halogen atom, and R.sup.2 and n are as defined in the above)
It is preferable that this reaction is conducted in an organic solvent, for example acetone, methylethylketone, diethylketone or dimethylformamide etc. under a reaction temperature of the room temperature to the solvent refluxing temperature. In addition, the presence of an inorganic base, for example potassium carbonate or sodium carbonate and further the addition of potassium iodide are also recommendable.
In the compounds of the general formula (VI), dimethylaminocarbonyl group or benzyl group etc. can be exemplified as the protective group for thiol group.
(4) The compounds represented by the general formula (IIa) can also be prepared by the following process. The compounds of the general formula (VI) are allowed to react with compounds of the general formula (VIIIa) to give compounds of the general formula (IX). EQU Y--(CH.sub.2).sub.n --Y.sup.1 (VIIIa)
(wherein Y and Y.sup.1 indicate identical or different halogen atom, and n is an integer from 3 to 8) ##STR11## (wherein R.sup.3 indicates a protective group, Y.sup.1 and n are as defined in the above)
It is preferable that this reaction is conducted in an organic solvent, for example acetone, methylethylketone, diethylketone or dimethylformamide under a reaction temperature of the room temperature to the solvent refluxing temperature. Then, the compounds represented by the general formula (IX) are allowed to react with sodium cyanide or potassium cyanide to give compounds of the general formula (X). ##STR12## (wherein R.sup.3 and n are as defined in the above)
It is preferable that this reaction is conducted in an organic solvent, for example dimethyl sulfoxide or dimethylformamide under a temperature of the room temperature to 100 .degree. C. Further, the compounds represented by the general formula (X) are subjected to hydrolysis and then to esterification with alcohol to give the compounds of the general formula (IIa). The hydrolysis of nitrile proceeds preferably with sodium hydroxide or potassium hydroxide in aqueous solution, and the esterification is preferably performed by refluxing in alcohol and in the presence of conc. sulfuric acid or a certain amount of a catalyst.
(5) Compounds represented by the general formula (IVa) can be prepared by allowing the compounds of the general formula (IIa) to react with compounds of the general formula (VIII). ##STR13## (wherein R.sup.2 indicates methyl group or ethyl group, Y.sup.1 indicates a halogen atom, m is an integer from 2 to 5 and n is an integer from 3 to 8) EQU Y--(CH.sub.2).sub.m --Y.sup.1 (VIII)
(wherein Y indicates a halogen atom, Y.sup.1 and m are as defined in the above)
It is preferable that this reaction is conducted in an organic solvent, for example acetone, methylethylketone, diethylketone or dimethylformamide under a reaction temperature of the room temperature to the solvent refluxing temperature. In addition, the presence of an inorganic base, for example potassium carbonate or sodium carbonate and further the addition of potassium iodide are also preferable.
(6) Compounds of the general formula (III) or (IV), in which X.sup.1 and X.sup.2 are both sulfinyl group, can be prepared by oxidizing compounds represented by the general formula (IIIa) or (IVa). ##STR14## (wherein Y indicates a halogen atom and m is an integer from 2 to 5) ##STR15## (wherein Y.sup.1 indicates a halogen atom, R.sup.2 indicates methyl group or ethyl group, m is an integer from 2 to 5 and n is an integer from 3 to 8)
The compounds of the general formula (III) or (IV) can typically be prepared by allowing the compounds represented by the general formula (IIIa) or (IVa) to react with a mild oxidizing agent, for example m-chloroperbenzoic acid, hydrogen peroxide etc., of equimolar or excess amount in an adequate solvent, for example methylene chloride, alcohol etc. respectively.
(7) Compounds of the general formula (III) or (IV), in which X.sup.1 and X.sup.2 are both sulfonyl group, can be prepared by allowing the compounds of the general formula (IIIa), (IVa) to react likewise as in (6), but with not less than bimolar amount of the mild oxidizing agent.
(8) Compounds of the general formula (I), in which R.sup.1 is methyl group or ethyl group X.sup.1 is oxygen atom or sulfonyl group and X.sup.2 is sulfinyl group, and compounds of the general formula (I), in which R.sup.1 is methyl group or ethyl group, X.sup.1 is sulfinyl group and X.sup.2 is an oxygen atom or sulfonyl group, can be respectively prepared by allowing the compounds represented by the general formula (Ia'), (Ib') to react with equimolar or excess amount of the mild oxidizing agent likewise as in (6). ##STR16## (wherein R.sup.2 indicates methyl group or ethyl group, m is an integer from 2 to 5, n is an integer from 3 to 8, and X.sup.1 indicates oxygen atom or sulfonyl group) ##STR17## (wherein R.sup.2, m, n and X.sup.2 are defined in the above)
(9) Compounds of the general formula (I), in which R.sup.1 is methyl group or ethyl group, X.sup.1 oxygen atom or sulfonyl group and X.sup.2 is sulfonyl group, and compounds of the general formula (I), in which R.sup.1 is methyl group or ethyl group, X.sup.1 is sulfonyl group and X.sup.2 is oxygen atom or sulfonyl group can be respectively prepared by allowing the compounds represented by the general formula (Ia'), (Ib') to react with the mild oxidizing agent likewise as in (6) but with not less than bimolar amount.

Phenoxyalkylcarboxylic acid derivatives and process for their preparations


Metal ions selected from the group consisting of Fe.sup.+3, Mn.sup.+2, Cu.sup.+2 and Zn.sup.+2 are administered to plant roots in a composition comprising citric acid, whereas the molar ratio of citric acid to metal ions in this composition is about 0.8 to 2.5.

Various metal ions are essential elements in plant nutrition and soil deficiency thereof is very often the cause of poor plant growth. Of particular importance for plant growth are iron, manganese, copper and zinc ions, iron being especially important. The following description of the prior art will focus in particular on the problems associated with the iron administration, but it should be understood that similar problems are associated also with the administration of the other three metals mentioned before.
Iron ions in the soil are present either in their di--(Fe.sup.+2) or trivalent (Fe.sup.+3) form, neutral or alkaline conditions favouring the latter. In their trivalent form iron ions hydrolyse water to form highly stable precipitates, the solubility coefficient being in the order of 10.sup.38. Thus, in soils having a neutral or basic pH, such as calcareous soils in which the calcium carbonate acts as a buffer maintaining a high pH, iron precipitates rapidly becoming unavailable to plants' roots.
It has been hitherto proposed to administer iron in a divalent ionic salt form. However, this method did not prove to be sufficiently efficient.
The most widely accepted method for the administration of iron is in the form of a complex of a synthetic chelate, in particular FeEDDHA or FeEDDHMA (Chen and Barak, 1982, Advances in Agronomy, 35:217-239). The main disadvantage of these synthetic chelates is in their high price (see, for example, Barak and Chen, 1987, Soil Sci. Soc. Am. J. 51:893-896) but, as noted by Barak and Chen and others, the use of FeEDDHA to the administration of iron to the soil was nevertheless the method of choice. The high efficiency of using the synthetic chelate EDDHA for the administration of iron has also been shown by Bell, 1977 (Principles and Application of Metal Chelation, Clarendon Press, Oxford).
The use of organic acids, such as citrate, as chelating agents of metal ions has been proposed but as has been shown (e.g. Bell, 1977, supra), citrate was found to be far inferior in its properties than the above synthetic chelating agents at pH below 11 (see page 133, fourth paragraph of Bell, 1977, supra). As shown by Cline et al., 1982 (Soil Sci. Soc. Am. J. 46:1158-1164), ion chelates comprising citrate as the chelating agent were unstable at pH above 7.
A composition comprising citric acid and metal ions has been described in SU-886874. The composition according to this patent is probably a pesticidal composition intended for topical application onto plant leaves and comprises various other ingredients including an adherent substance and sulfur which latter is probably the pesticidally active agent. A compositon comprising ferric ions and citric acid has been described in CA-1,152,769. The composition according to this latter patent comprises also a nitrogen source which is an essential ingredient, and is used for the topical administration of ferric ions to plants, via their leaves. None of these patents discloses or even suggests that citric acid may be used as a chelating agent in composition for administering metal ions to plant roots.
The prior art thus taught away from using organic acids in general, and citrate in particular, as chelating agents for the administration of metal ions to the soil in a form available to plant roots. The entire research was concentrated on finding more efficient ways of using synthetic chelates to this end.

Fertilizer compositions for administering ionic metal microelements to plant roots


A pattern recognition method of dynamic time warping of two sequences of feature sets onto each other is provided. The method includes the steps of creating a rectangular graph having the two sequences on its two axes, defining a swath of width r, where r is an odd number, centered about a diagonal line connecting the beginning point at the bottom left of the rectangle to the endpoint at the top right of the rectangle and also defining r-1 lines within the swath. The lines defining the swath are parallel to the diagonal line. Each array element k of an r-sized array is associated with a separate array of the r lines within the swath and for each row of the rectangle, the dynamic time warping method recursively generates new path values for each array element k as a function of the previous value of the array element k and of at least one of the current values of the two neighboring array elements k-1 and k+1 of the array element k. The latter step of recursively generating new path values is repeated for all of the rows of the rectangle and the value of the middle array element is selected as the output value sought.

Pattern recognition systems are used, for example, for the recognition of characters and speech patterns.
Pattern recognition systems are known which are based on matching the pattern being tested against a reference database of pattern templates. The spectral distance between the test pattern and the database of reference patterns is measured and the reference pattern having the closest spectral distance to the test pattern is chosen as the recognized pattern.
An example of the prior art pattern recognition system using a distance measure calculation is shown in FIGS. 1, 2 and 3, to which reference is now made. FIG. 1 is a flow chart illustrating the prior art pattern recognition system for speech patterns using a conventional linear predictor coefficient (LPC) determiner and a distance calculator via dynamic time warping (DTW). FIG. 2 illustrates the relationship between two speech patterns A and B, along i-axis and j-axis, respectively. FIG. 3 illustrates the relationship between two successive points of pattern matching between speech patterns A and B.
Referring to FIG. 1, the audio signal 10 being analyzed, has within it a plurality of speech patterns. Audio signal 10 is digitized by an analog/digital converter 12 and the endpoints of each speech pattern are detected by a detector 14. The digital signal of each speech pattern is broken into frames and for each frame, analyzer 16 computes the linear predictor coefficients (LPC) and converts them to cepstrum coefficients, which are the feature vectors of the test pattern. Reference patterns, which have been prepared as templates, are stored in a database 18. A spectral distance calculator 20 uses a dynamic time warping (DTW) method to compare the test pattern to each of the reference patterns stored in database 18. The DTW method measures the local spectral distance between the test pattern and the reference pattern, using a suitable method of measuring spectral distance, such as the Euclidean distance between the cepstral coefficients or the weighted cepstral distance measure. The template whose reference pattern is closest in distance to the analyzed speech pattern, is then selected as being the recognized speech pattern.
In a paper, entitled "Dynamic Programming Algorithm Optimization for Spoken Word Recognition", published by the IEEE Transactions on Acoustics, Speech and Signal Processing in February 1978, Sakoe and Chiba reported on a dynamic programming (DP) based algorithm for recognizing spoken words. DP techniques are known to be an efficient way of matching speech patterns. Sakoe and Chiba introduced the technique known as "slope constraint", wherein the warping function slope is restricted so as to discriminate between words in different categories.
Numerous spectral distance measures have been proposed including the Euclidean distance between cepstral coefficients which is widely used with LPC-derived cepstral coefficients. Furui in a paper, entitled "Cepstral Analysis Techniques for Automatic Speaker Verification", published by the IEEE Transactions on Acoustics, Speech and Signal Processing in April 1981, proposed a weighted cepstral distance measure which further reduces the percentage of errors in recognition.
In a paper, entitled "A Weighted Cepstral Distance Measure for Speech Recognition", published by the IEEE Transactions on Acoustics, Speech and Signal Processing in October 1987, Tahkura proposed an improved weighted cepstral distance measure as a means to improve the speech recognition rate.
Referring now to FIG. 2, the operation of the DTW method will be explained. In FIG. 2, speech patterns A and B are shown along the i-axis and j-axis, respectively. Speech patterns A and B are expressed as a sequence of feature vectors a.sub.1, a.sub.2, a.sub.3 . . . a.sub.m and b.sub.1, b.sub.2, b.sub.3 . . . b.sub.m, respectively.
The timing differences between two speech patterns A and B, can be depicted by a series of `points` Ck(i,j). A `point` refers to the intersection of a frame i from pattern A to a frame j of pattern B. The sequence of points C1, C2, C3 . . . Ck represent a warping function 30 which effects a map from the time axis of pattern A, having a length m, on to the time axis of pattern B, having a length n. In the example of FIG. 2, function 30 is represented by points c1(1,1), c2(1,2), c3(2,2), c4(3,3), c5(4,3) . . . ck(n,m). Where timing differences do not exist between speech patterns A and B, function 30 coincides with the 45 degree diagonal line (j=i). The greater the timing differences, the further function 30 deviates from the 45 degree diagonal line.
Since function 30 is a model of time axis fluctuations in a speech pattern, it must abide by certain physical conditions. Function 30 can only advance forward and cannot move backwards and the patterns must advance together. These restrictions can be expressed by the following relationships: EQU i(k)-i(k-1).ltoreq.1 and (j(k)-j(k-1).ltoreq.1; and i(k-1).ltoreq.i(k) and j(k-1).ltoreq.j(k). (1)
Warping function 30 moves one step at a time from one of three possible directions. For example, to move from C3(2,2) to C4(3,3), function 30 can either move directly in one step from (2,2) to (3,3) or indirectly via the points at (2,3) or (3,2).
Function 30 is further restricted to remain within a swath 32 having a width r. The outer borders 34 and 36 of swath 32 are defined by (j=i+r) and (j=i-r), respectively.
A fourth boundary condition is defined by: EQU i(1)=1, j(1)=1, and i(end)=m, j(end)=n. (2)
Referring now to FIG. 3, where, for example, the relationship between successive points C10(.sub.10,10) and C11(.sub.11,11), of pattern matching between speech patterns A and B is illustrated. In accordance with the conditions as described hereinbefore, there are three possible ways to arrive at point C11(.sub.11,11), that is, either directly from C10(.sub.10,10) to C11(.sub.11,11), indicated by line 38 or from C10(.sub.10,10) via point (.sub.11,10) to C11(.sub.11,11), indicated by lines 40 and 42, or thirdly from C10(.sub.10,10) via point (.sub.10,11) to C11(.sub.11,11), indicated by lines 44 and 46.
Furthermore, associated with each arrival point (i,j), such as point C11(.sub.11,11), is a weight W.sub.ij, such as the Euclidean or Cepstral distance between the ith frame of pattern A and the jth frame of pattern B. By applying a weight W.sub.ij to each of indirect paths 40, 42, 44 and 46 and a weight of 2W.sub.ij to direct path 38, the path value S.sub.ij, at the point (ij) can be recursively ascertained from the equation: ##EQU1##
In order to arrive at endpoint S.sub.nm, it is necessary to calculate the best path value S.sub.ij at each point. Row by row is scanned and the values of S.sub.ij for the complete previous row plus the values of the present row up to the present point are stored. The value for Snm is the best path value.

Art-Advanced Recognition Technologies Inc.


A first belt tensioner includes an arm, spring case, coil spring, and arm plate. The arm is adapted to support an idler pulley and has a hook portion. The spring case is disposed in the arm and has a first spring seat. The spring is disposed in the spring case. The arm plate has a second spring seat. The spring is longitudinally compressed between the arm plate and the spring case. The spring is in torsion with the end portions of the spring seated against a corresponding spring seat and with the arm plate rotationally positioned under the hook portion. A method for assembling the first belt tensioner includes using the arm plate to longitudinally compress the spring and rotating the arm plate. A second belt tensioner includes an arm, spring case, coil spring, arm plate, and pivot bushing.

The automotive industry utilizes belt tensioners to create a generally constant tension on a belt as it changes in length from normal wear, or from changes in span lengths due to span speed differences, wherein the belt is driven by a single drive pulley from the output shaft of the engine and wherein the belt rotates driven pulleys, each operating an automotive accessory. In known designs, the belt tensioner includes either a flat-wound spring or a helical spring, a spring casing, and an arm. One end of the spring is attached to the spring casing and the other end of the spring is attached to the arm. The arm pivots with respect to the spring casing when the spring exerts torque. The spring casing is attached to the engine, and an idler pulley is attached to the arm. The spring is preloaded by twisting the arm relative to the spring casing. The idler pulley on the arm is then placed against the belt. As the belt span lengthens, the torque from the preloaded spring continues to cause the idler pulley of the arm to apply pressure against the belt keeping the belt in tension.
In one known arrangement patented as U.S. Pat. No. 5,772,549, a helical spring has a first end screwed into a first screw-like passage of the arm of the spring tensioner and has a second end screwed into a second screw-like passage of the spring casing. The spring is under tension and holds the parts together while permitting the arm to rotate relative to the spring casing. A cone-shaped bushing is disposed inside the spring between a portion of the arm and a portion of the spring casing to facilitate the rotation of the arm relative to the spring casing. This arrangement is open to contamination and the spring configuration creates a moment loading.
In one known example of a belt tensioner, a square-shaped hole in the idler pulley is engaged by a square head, often as would be common to a ½″ or ⅜″ leveraging or ratchet or similar wrench, to lift (preload) the arm. In a different known example, the idler pulley is mounted on a post of the arm, wherein the post has an annular rim which is deformed radially outward and over the bearing of the idler pulley creating a radial rivet joint to retain the idler pulley to the arm
In one known method, the arm is cast using a mold having first and second sections, and the spring case is cast using a mold having first and second segments. In this method, a path in the belt tensioner from the arm's seat for the bearing of the idler pulley to the engine mounting surface of the spring case crosses a line on the spring case corresponding to the parting line of the first and second segments.
Still, engineers continue to seek improved belt tensioners.


An oil free screw compressor having a low-pressure stage compressor body and a high-pressure stage compressor body. Power of a motor driven by an inverter is transmitted to the compressor bodies through gears. A low-pressure stage blow-off two-way valve is provided in a pipe branching off midway an air pipe connecting between the high-pressure stage compressor body and the low-pressure stage compressor body, and a high-pressure stage blow-off two-way valve is provided in a pipe branching off from a discharge air pipe provided on a discharge side of the high-pressure stage compressor body. During no-load operation, a controller gives a command to the inverter to make the rotational speed of the motor a set lower limit rotational speed, and also gives an open command to the low-pressure stage blow-off two-way valve.

The present invention relates to a variable rotational speed oil free screw compressor and a control method therefor and, more particularly, to a variable rotational speed oil free screw compressor having a low-pressure stage compressor body and a high-pressure stage compressor body and a control method therefor.
In a conventional variable rotational speed oil free screw compressor, for example, as disclosed in Japanese Patent Laid-Open No. 82391/1998, a low-pressure stage screw compressor body and a high-pressure stage screw compressor body are connected to each other in series, and a cooler is provided between the two compressing sections. A motor is connected to each of the low-pressure stage screw compressor body and the high-pressure stage screw compressor body, and the motor is driven at a variable speed by an inverter. In the variable rotational speed oil free screw compressor constructed above, with a small flow rate, both of the low-pressure stage screw compressor body and the high-pressure stage screw compressor body rotate at low speed, so that an amount of internal leakage cannot be ignored. Therefore, a blow-off valve is connected to an outlet pipe, by which blow-off control is carried out while the low-pressure stage screw compressor body and the high-pressure stage screw compressor body are operated at the lowest rotational speed.
With an oil free screw compressor having two stages of low-pressure and high-pressure stages, power consumption with no load is smaller than that with full load as compared with a single-stage oil free screw compressor. Therefore, even if the method disclosed in the above-described Publication is applied at the time of no-load operation, there is a disadvantage that power consumption is not decreased so much as compared with a conventional method, in which a suction throttle valve is throttled.
The present invention has been contrived in view of the above problems of the prior art, and has its object to provide a variable rotational speed oil free screw compressor having a low-pressure stage compressor body and a high-pressure stage compressor body, in which power consumption is reduced both at no load and at low load.
A first feature of the present invention for attaining the above object is a variable rotational speed oil free screw compressor, comprising a low-pressure stage compressor body and a high-pressure stage compressor body, which are variable in rotational speed, and blow-off means for blowing off compressed air to the atmosphere midway a pipe connecting between the high-pressure stage compressor body and the low-pressure stage compressor body. In this feature, it is preferable that an inter-cooler and blow-off means is provided midway the pipe connecting between the high-pressure stage compressor body and the low-pressure stage compressor body, and an after-cooler is provided on a discharge side of the high-pressure stage compressor body. Also, another blow-off valve may be provided between the high-pressure stage compressor body and a check valve to blow off compressed air discharged from the high-pressure stage compressor body, and wherein compressed air is blown off through the blow-off valve and another blow-off valve at the time of no-load or low-load operation.
Also, a pressure detector may be provided on the discharge side of the high-pressure stage compressor body for detecting pressure of high-pressure air discharged from the high-pressure stage compressor body, and a controller may be provided to receive a signal of discharge pressure detected by the pressure detector and output a control signal for controlling the blow-off means. The variable rotational speed oil free screw compressor may further comprise an electric motor for rotatingly driving the low-pressure stage compressor body and the high-pressure stage compressor body, and an inverter for driving the electric motor, and wherein the controller controls the inverter based on a signal of discharge pressure detected by the pressure detector.
Preferably, a suction throttle valve is provided on a suction side of the low-pressure stage compressor body, and another blow-off means is provided on a discharge side of the high-pressure stage compressor body, another blow-off means interconnecting with the suction throttle valve.
A second feature of the present invention for attaining the above object is a method of controlling a variable rotational speed oil free screw compressor adapted to operate in accordance with a volume of consumed air on a usage side while changing rotational speeds of a low-pressure stage compressor body and a high-pressure stage compressor body, the method comprising the steps of: performing a load operation to change rotational speeds of the low-pressure stage compressor body and the high-pressure stage compressor body in a region, in which a volume of consumed air based on pressure detected by a pressure detector provided on a discharge side ranges from a maximum air volume to a preset volume of air; operating the low-pressure stage compressor body and the high-pressure stage compressor body at set lower limit rotational speeds preset every compressor body in a no-load operation, in which a volume of consumed air is substantially zero, and blowing off compressed air from blow-off means provided in a pipe connecting between the high-pressure stage compressor body and the low-pressure stage compressor body; and repeating the load operation and the no-load operation when a volume of consumed air is equal to or smaller than a set air volume.
Preferably, during the load operation, the rotational speeds of the low-pressure stage compressor body and the high-pressure stage compressor body are changed substantially in proportion to a volume of consumed air. Also preferably, during no-load operation, compressed air discharged from the high-pressure stage compressor body is blown off.
A third feature of the present invention for attaining the above object is a method of controlling a variable rotational speed oil free screw compressor adapted to operate in accordance with a volume of consumed air on a usage side while changing rotational speeds of a low-pressure stage compressor body and a high-pressure stage compressor body, the method comprising the steps of: performing operations including a no-load operation to blow off compressed air from blow-off means provided in a pipe connecting between the high-pressure stage compressor body and the low-pressure stage compressor body when a volume of consumed air based on pressure detected by a pressure detector provided on a discharge side is not exceeding a preset volume of air and pressure of compressed air discharged from the low-pressure stage compressor body is at least the atmospheric pressure.
A suction throttle valve provided on a suction side of the low-pressure stage compressor body may be made to interlock with blow-off means for compressed air compressed by the high-pressure stage compressor body to make control to throttle the suction throttle valve when a volume of consumed air is not exceeding a set air volume.

Oil free screw compressor operating at variable speeds and control method therefor


In a moving magnet type linear motor including a stator with a plurality of coils placed in one direction and a mover with a permanent magnet opposed to the stator, a position detector detects the position of the mover. The position detector includes a magnetic body fixed to the mover. One or two or more coils are selected and a voltage is applied to the selected coil while a current or a voltage induced in a coil adjacent to the selected coil is measured, and the position of the magnetic body that changes in response to the position of the mover is determined based on the measured current or the measured voltage.

In a moving magnet type linear motor with coils provided to a stator and a permanent magnet provided to a mover, expensive magnets are not required to be placed along a path. Further, the mover does not generate heat, and does not require power supply. So, the moving magnet type linear motor is widely used as a driving source of a transport mechanism especially with a long path.
In this moving magnet type linear motor, the stator has a plurality of coils placed in one direction, and the permanent magnet of the mover is so placed as to be opposed to the coils of the stator. So, when a polyphase alternating voltage is applied to the coils of the stator to form a shifting magnetic field, thrust to act in the same direction as the shifting magnetic field is generated in the mover, by which the mover is caused to move in the direction.
In recent years, such use of the moving magnet type linear motor as a driving source of an elevator as is described above has been suggested (as introduced for example in patent document 1).

Position detector for moving magnet type linear motor


A coupling device for mechanically coupling a fuel rail to a cylinder head of a combustion engine comprises a fuel injector cup designed to be hydraulically and mechanically coupled to the fuel rail and comprising a through hole extending between a first surface and a second surface of the fuel injector cup, the second surface arranged to face the cylinder head, and a fastening element designed to be fixedly coupled to the cylinder head, the fastening element comprising a head portion facing the first surface of the fuel injector cup and a shank portion partially arranged in the through hole and designed to be in engagement with the cylinder head. The coupling device comprises a first spring element arranged axially between the head portion and the first surface of the fuel injector cup, and a second spring element facing the second surface of the fuel injector cup and arrangeable axially between the second surface of the fuel injector cup and the cylinder head.

Coupling devices for hydraulically and mechanically coupling a fuel rail to a cylinder head of a combustion engine are in widespread use, in particular for internal combustion engines. Fuel can be supplied to an internal combustion engine by the fuel rail through a fuel injector. The fuel rail can be coupled to the cylinder head in different manners.
In order to keep pressure fluctuations during the operation of the internal combustion engine at a very low level, internal combustion engines are supplied with a fuel accumulator to which the fuel injectors are connected and which has a relatively large volume. Such a fuel accumulator is often referred to as a common rail. Known fuel rails comprise a hollow body with recesses in form of fuel injector cups, wherein the fuel injectors are arranged.


Apparatus for supplying water to a Christmas tree stand continuously from a large reservoir including a supporting stand to maintain a constant level supply of water and a delivery tube to provide a siphon action to supply water to the tree stand.

This invention relates broadly to apparatus for supplying water to a supporting stand of the type used for cut Christmas trees and more specifically to method and apparatus for maintaining a constant water level in such a tree stand by providing a continuous flow from a constant level remote reservoir.
It is common practice in the United States to display within the home during the Christmas Season decorated evergreen trees which have been cut and sold specifically for such display which normally lasts only a few weeks. In order to keep the tree as well preserved as possible and to prevent it from drying out and losing its needles, it is common to employ a stand which includes a water receptacle in which the bottom or cut end of the tree's trunk is immersed. By keeping the bottom end of the trunk so immersed in water, the owner reduces the possible fire hazard which a dried out tree would present.
One of the problems with such tree stands is the fact that it is difficult to observe the water level in the tree stand receptacle and it is also difficult to fill the receptacle when the water evaporates therefrom or is absorbed by the tree supported therein.
The recently issued U.S. Pat. No. 4,653,224 to Weckesser is illustrative of one approach to solving these problems. The Weckesser patent is directed to a Christmas tree irrigation device that supplies water from a separate receptacle through a flexible tube to the water container in a tree stand. The device of the Weckesser patent includes no means to continuously supply water to the tree stand and requires that the user observe the water level in the tree stand to determine when additional water is needed and how much water is needed. It would be preferable to have an irrigation or watering device which would automatically supply water on a continuous basis to the tree stand to maintain a predetermined, constant level of water therein.

Apparatus for supplying water continuously to tree stand


A method and apparatus is disclosed for improving the performance of a digital computer by reducing the latency of read operations and increasing available write bandwidth by utilizing a subset of the address bits which are the same from one operation to the next. A faster cycle type (e.g. page mode or static column) can thereby be employed in the Dynamic Random Access Memory (DRAM) memory by eliminating the DRAM precharge and RAS address portions of the cycle.

High speed computer memories, in particular cache memory performance is strongly influenced by the amount of time necessary to fill the cache memory with new data required by the processor. The sooner such a read operation can be started in main memory, the less time it will take to fill the cache. The influence of read latency on performance is derived from the read latency times the cache miss rate. This is the amount of time by which an average processor cycle will be increased due to cache read latency.

Method and apparatus for DRAM memory performance enhancement


Discussed herein are devices, systems, and methods for software-based animation. A method can include receiving data indicating a first object name, a corresponding file path of a model, a camera location, a reference point, and an animation of the first object, the animation comprising a stack of atomic animation functions that affect the view of one or more of the first object or the camera, storing the object name, the file path, the camera location, the reference location, and atomic animation functions in a memory, in response to receiving data indicating the first object was selected, automatically retrieving the model based on the file path, providing, by the display, a view of the model of the first object consistent with the camera location and the reference point, and executing the stored atomic animation functions to animate the model of the first object.

3D image development is typically very labor intensive. A graphic artist can develop different perspective views of the object. Each perspective developed typically requires the graphic artist to laboriously and tediously generate a new rendering of a 3D object in the image. This is especially tedious and time consuming for moving views of the object in the 3D image.

Efficient three-dimensional, interactive image rendering


A method for fabrication of semiconductor device in which a tungsten film only exists on contact hole which is comprising the steps of depositing a insulator layer on the silicon substrate being doped by impurity, depositing a photoresist high temperature resistant resin on the insulator layer in order to form a contact hole, forming a contact hole by etching the insulator layer using the photoresist resin as a mask, selectively depositing tungsten film on the contact hole and removing the photoresist layer, and a method for fabrication of semiconductor device which is comprising the steps of depositing the first photoresist resin layer followed by depositing the second photoresist resin layer on the insulator layer forming a pattern to the first and the second photoresist resin layer, forming a contact hole by etching the insulator layer, selectively depositing tungsten film on the contact hole after removing the second photoresist resin layer and removing the first photoresist resin layer.

The present invention relates to method for the fabrication of a semiconductor device and, more particularly to a method for selective deposition of tungsten film into a contact hole by a chemical evaporating method during a process for deposition of metallic circuits on the contact hole.
It is already known that the selective deposition of tungsten film into deep contact hole by a chemical evaporating method during fabricating a metallic circuit is a very useful technique.
However, there are two critical problems in the conventional selective deposition technique of tungsten film which is to be improved.
That is,
(1) Tungsten residue 5 remains on the insulator layer 3 because of selective loss between silicon substrate 1 and the insulator layer 3, as shown in FIG. 3.
(2) Leakage current increases due to tunneling caused by enchroachment of electrodes.
In order to remove tungsten residue 5 on the insulator layer 3, it was proposed to clean the surface of the insulator before the deposition of the tungsten film after fabricating a contact hole by a plasma etching method, or to etch back the residue after deposition of the tungsten film.
However, the methods mentioned above are not desirable, because the reproducibility of the process deteriorates if there is cleaning of the surface of the insulator before the deposition of the tungsten film. Moreover, the etchback method overetched inside of the contact hole resulting in water or other chemical substances attacking during the succeeding process as shown in FIG. 4.

Method of preventing residue on an insulator layer in the fabrication of a semiconductor device


A method and apparatus for mounting an airbag module to a vehicle, the apparatus comprising a backing plate for mounting the airbag module to the vehicle, the backing plate comprising: a plurality of elongated mounting members each being drawn from the material of the backing plate wherein the plurality of elongated mounting members are integrally formed with the backing plate and each of the plurality of elongated mounting members has a portion comprising a periphery formed from the material of the backing plate and an opening extending into the elongated mounting member, the opening defining the periphery of the plurality of elongated mounting members. The method comprising: stamping a blank material to form a periphery and a central opening of the backing plate, wherein a mounting surface is located between the central opening and the periphery; and deep drawing at least one mounting member from the mounting surface, wherein the at least one mounting member provides a securement feature for the backing plate.

This application is also related to U.S. Pat. Nos. 5,380,037; 6,196,573; and 6,237,944, the contents of which are also incorporated herein by reference thereto.
Vehicles are supplied with driver side airbag modules; generally the driver side airbag module is located in the center of the steering wheel. This is also the same location where a horn-activating switch has traditionally been mounted. In addition, other inflatable cushions or airbag modules have been installed in vehicles.
Various mounting mechanisms have been used for securing airbag modules to support structures in a vehicle. Non-limiting examples of such support structures include steering wheels and vehicle instrument panels. In one known mounting mechanism, mounting bolts are passed through openings in the vehicle support structures wherein a threaded portion of the mounting bolts engages a complimentary nut or threaded portion of the airbag module.
Another mechanism for use with a driver side airbag module includes a means for providing a horn activation circuit wherein horn contact members are forced into contact in order to complete a horn activation circuit.
However, current attachment mechanisms for use with driver side airbag modules comprising horn activation circuits comprise numerous parts that require additional installation steps and costs.
Therefore, it is desirable to provide an apparatus and method for providing a securement feature for an airbag module that uses a minimal amount of components and is easy to install and manufacture thereby reducing the associated costs.

Airbag module with integral locking mechanism and method of making


A fastener assembly for detachably connecting a molded door trim panel to an apertured inner door panel of a vehicle, where upon disassembly, the fastener assembly will disengage, or a replaceable portion will fracture without damaging the molded door trim panel. A detent is utilized to connect a hook portion to a retainer housing that is molded into the molded door trim panel. Upon the hook portion being mistakenly pulled against the inner door panel during disassembly, the detent will either disengage the hook portion from the retainer housing, or the hook portion will fracture before the retainer housing is damaged or disconnected from the molded door trim panel. By preventing damage to the retainer housing and molded door trim panel, only the hook portion of the hook fastener assembly need be replaced or reconnected, instead of the entire molded door trim panel.

It is well known to use rigid hooks for connecting a molded door trim panel to an inner door panel of a vehicle. Such rigid hooks are typically molded into the molded door trim panel and utilized to engage corresponding apertures in the inner door panel. Upon servicing the door, it is often desired to remove the molded door trim panel from the inner door panel. Since the rigid hooks are hidden behind the inner door panel, the disassembler cannot see how the rigid hooks disconnect from the inner door panel. Upon pulling the molded door trim panel from the inner door panel, the rigid hook may be pulled against the inner door panel causing the rigid hook to fracture or become disconnected from the molded door trim panel. Because the rigid hooks are molded into the molded door trim panel, the entire molded door trim panel must be replaced. Such replacement is costly in light of the fact that the entire assembly must be replaced.
It would be desirable to provide a new and improved fastener assembly that detachably connects a molded door trim panel to an inner door panel of a vehicle and permits removal of the molded door trim panel without damage.

Fastener assembly for detachably connecting a door trim panel


A power generation system and method includes a first gas turbine system comprising a first combustion chamber configured to combust a first fuel stream of primarily hydrogen that is substantially free of carbon-based fuels. The first gas turbine system also includes a first compressor configured to supply a first portion of compressed oxidant to the first combustion chamber and a first turbine configured to receive a first discharge from the first combustion chamber and generate a first exhaust and electrical energy. The power generation system further includes a second gas turbine system comprising a second combustion chamber configured to combust a second fuel stream to generate a second discharge. The first compressor of the first gas turbine system is configured to supply a second portion of compressed oxidant to the second combustion chamber. The second turbine system also includes a second turbine configured to receive the second discharge from the second combustion chamber to generate a second exhaust and electrical energy and a second compressor configured to receive the second discharge comprising carbon dioxide. The second compressor is also configured to discharge a recycle stream to the second combustion chamber and a split stream to a separator system adapted to recover carbon dioxide.

The invention relates generally to power generation and the efficient recovery of carbon dioxide. More particularly, the invention relates to the integration of gas-turbine exhaust compression/recirculation with carbon dioxide separation/recovery.
Power generation systems that combust fuels containing carbon (e.g., fossil fuels) produce carbon dioxide (CO2) as a byproduct, because in the combustion, carbon is converted to CO2. Removal or recovery of the carbon dioxide (CO2) from power generation systems, such as from the exhaust of a gas turbine, is generally not economical due to low CO2 content and low (ambient) pressure of the exhaust. Therefore, unfortunately, the exhaust containing the CO2 is typically released to the atmosphere, and does not get sequestered into oceans, mines, oil wells, geological saline reservoirs, and so on. There is a need for a technique that provides for economical recovery of CO2 discharged from power generation systems (e.g., gas turbines) that rely on carbon-containing fuels.

Systems and methods for power generation with carbon dioxide isolation


The present description provides a water-reducible or water-dispersible coating system that can be used to form a durable, corrosion-resistant protective coating on a wide range of substrates. The coating system includes an alkyd resin prepared from a polyester feedstock that includes post-consumer recycled PET and a waste cooking oil feedstock. Methods for preparing the coating system and articles coated with the coating system are also described.

Alkyd resins are polyester resins derived from the reaction of polyols with dicarboxylic acids or anhydrides, and modified by fatty acids. Conventional methods for making alkyd resins use fatty acids derived from vegetable oils, tall oils, short oils, and the like. Although alkyd resins are typically solvent-based, environmental concerns over volatile organic compound (VOC) content in coating compositions has led to interest in water-reducible or water-dispersible alkyd resins.
Environmental concerns over increasing quantities of waste or post-consumer materials have created interest in coating compositions made from waste materials. For example, fast food restaurants generate large quantities of used vegetable oil or waste oil. The waste cooking oil can pose a pollution hazard and has the potential to clog waterways and drain systems during disposal. Therefore, used cooking oil, called yellow grease or brown grease, is typically trapped and filtered out of waste water streams and rendered into animal feed, biodiesel fuel and the like. In addition, waste cooking oil may be used as a fatty acid feedstock for producing alkyd resins, although these alkyd resins may lack the hardness, durability and early water resistance required of a water-reducible coating composition.
Other waste or post-consumer materials may also be used as feedstock for making alkyd resins. For example, polyethylene terephthalate is in widespread use, and recycling PET helps manage solid waste problems while conserving resources and energy. However, water-reducible resins with high PET content typically demonstrate poor water resistance and may not be useful in making corrosion-resistant coating compositions.
Therefore, in view of the foregoing, increasing environmental concerns may be met by new water-reducible or water-dispersible coatings derived from waste or post-consumer materials, where the coatings demonstrate optimal durability, water resistance and corrosion resistance.


Exemplary embodiments of the invention provide a casting apparatus for continuously casting a metal strip article (e.g. a twin-belt metal caster or a twin-block metal caster). The apparatus has a casting cavity defined between a pair of moving elongated opposed casting surfaces, and the casting cavity has an entrance and an exit aligned in a direction of casting. The casting cavity is also provided with a molten metal injector at its entrance, the injector having an internal metal channel including a downstream opening for introducing molten metal into the casting cavity, and a pair of side dams at each lateral side of the casting cavity for confining molten metal from the injector within the cavity. At least one of the side dams comprises an elongated element that is movable laterally relative to the direction of casting during a casting operation. The elongated element extends in the direction of casting from the injector longitudinally between the casting surfaces at least to a downstream position within the casting cavity where the metal adjacent the element is laterally self-supporting.

(1) Field of the Invention
This invention relates to the casting of metal strip articles by means of continuous strip casting apparatus of the kind that employs continuously moving elongated casting surfaces and side dams that confine the molten and semi-solid metal to the casting cavity formed between the moving casting surfaces. More particularly, the invention relates to such apparatus in which strip articles of variable width may be produced.
(2) Description of the Related Art
Metal strip articles (such as metal strip, slab and plate), particularly those made of aluminum and aluminum alloys, are commonly produced in continuous strip casting apparatus. In such apparatus, molten metal is introduced between two closely spaced (usually actively cooled) elongated moving casting surfaces forming a narrow casting cavity. The metal is confined within the casting cavity until the metal solidifies (at least sufficiently to form an outer solid shell), and the solidified strip article is continuously ejected from the casting cavity by the moving casting surfaces and may be produced in indefinite length. One form of such apparatus is a twin-belt caster in which two confronting belts are circulated continuously and molten metal is introduced by means of a launder or injector into a thin casting cavity formed between the confronting regions of the belts. An alternative is a rotating block caster in which the casting surfaces are formed by blocks that rotate around a fixed path and join together adjacent the casting cavity to form a continuous surface. The metal is conveyed by the moving belts or blocks for a distance effective to solidify the metal, and then the solidified strip emerges from between the belts at the opposite end of the apparatus.
In order to confine the molten and semi-solid metal within the casting cavity, i.e. to prevent the metal escaping laterally from between the casting surfaces, it is usual to provide metal side dams at each side of the apparatus. For twin-belt and rotating block casters, side dams of this kind can be formed by a series of metal blocks joined together to form a continuous chain aligned in the casting direction at each side of the casting cavity. These blocks, normally referred to as side dam blocks, are trapped between and move along with the casting surfaces and are recirculated so that blocks emerging from the mold exit move around a guided circuit and are fed back into the entrance of the mold. The blocks are guided on this circuit by means of a metal track, or the like, on which the blocks can slide in a loose fashion that allows for limited movement between the blocks, especially as they move around curved parts of the circuit.
When casting strip articles in this way, it is often desirable to produce strip articles of different lateral widths for different purposes. When using the conventional arrangement, this involves terminating the casting operation after the completion of casting of a product of a first width, and re-configuring the caster for the production of a strip article of a second width. For example, it may be necessary to replace one metal injector for a different one of different width, and to move the side dam blocks correspondingly towards or away from the center line of the casting surfaces (which involves moving the entire circuit for recirculating the side dam blocks through the casting cavity and around the external circuit). As this is cumbersome and time-consuming, it would be desirable to provide a system or arrangement for facilitating the change-over of the casting equipment when strip articles of different widths are to be produced.
U.S. Pat. No. 6,363,999 issued to Dennis M. Smith on Apr. 2, 2002 discloses a molten metal injector used with a twin roll caster (in which the metal is cast within the nip formed between the rolls) rather than a twin belt or moving block type caster in which the casting cavity is formed between elongated casting surfaces. The injector is provided with end dams along its sides and these are adjustable towards or away from the center line of the nip. However, the end dams do not extend beyond the nozzle of the molten metal injector.
U.S. pending patent application No. US 2008/0115906, published on May 22, 2008 naming Oren V. Peterson as inventor, describes a metal casting apparatus for steel in which molten metal is poured onto a single moving belt, where it at least partially solidifies, before it is conveyed onto a run-out table on which the solidification process is completed. The apparatus has movable side walls for laterally containing the molten metal and that can be adjusted to produce slabs of different widths. However, there is no upper casting surface and the molten metal is merely poured onto the lower belt rather than being injected from an entrance to a casting cavity.
Other references having side dam arrangements are disclosed, for example, in U.S. Pat. No. 3,063,348 issued on May 29, 1962 to Hazelett et al., U.S. Pat. No. 4,727,925 issued on Mar. 1, 1988 to Asari et al.; Japanese patent application No. JP 60-049841 published on Mar. 19, 1985, and Japanese patent application No. JP 61-0132243 published on Jun. 19, 1986.
There is a need for improved arrangements that can, in particular, make it possible to cast strip articles of different widths without terminating casting operations.

Continuous casting apparatus for casting strip of variable width