A mold of ductile metal has a shape comprising consecutive sub-shapes corresponding to respective optical sub-elements having substantially identical shapes arranged in a pattern. The mold is shaped by means of a die having a die surface corresponding to the sub-shape, which sub-shape is imprinted in the ductile metal with a predetermined force one at a time in consecutive positions in accordance with the pattern, each position corresponding to a single optical sub-element.

A method of manufacturing a mould and a method of manufacturing an optical element as mentioned in the opening paragraphs are known from JP-A-58-171021. The optical element to be manufactured by the known methods is a so-called lens array, which comprises a two-dimensional array of spherical lenses. According to the known methods, a die corresponding to the lens array is manufactured by joining together a number of sub-dies corresponding to the number of lenses of the lens array, each having a spherical die surface corresponding to a lens of the lens array, in the pattern of the lens array. The die is then pressed into a mold made from a clay-type ceramic material by means of a press, so that the mold is given a mould shape corresponding to the lens array, and the clay-type ceramic material of the mould is hardened in a heat treatment. Then a molten synthetic material is poured into the mold, put under pressure, and cooled down, so that a synthetic-resin lens array is formed which corresponds to the mold shape.
A disadvantage of the known methods is that the manufacture of the die used in the known methods is complicated and time-consuming because each sub-die of the die must be individually provided with a die surface corresponding to a lens of the lens array in an accurate manner. The known methods for this reason are particularly unsuitable for the manufacture of so-called microlens arrays which comprise a comparatively large number of microlenses of 1 mm, or even 0.1 mm diameter or smaller. In addition, no sharp boundaries between adjoining sub-moulds corresponding to individual lenses of the lens array arise in the mould because the clay-type ceramic material cannot fully penetrate the interstices between the sub-dies when the die is being pressed into the mould. As a result, the individual lenses of the lens arrays manufactured by means of the known mould merge fluently into one another, and the optically useful surface area of the lens array is limited by unsharp boundaries between the lenses of the lens array.
It is an object of the invention to provide a method of manufacturing a mold and a method of manufacturing an optical element of the kind as mentioned in the opening paragraphs wherein the disadvantages of the known methods mentioned above are avoided as much as possible, so that the mould and the optical element are manufactured in a manner which is less complicated and less time-consuming, while the optical elements manufactured by the methods have comparatively large optically useful surface areas.
According to the invention, the method of manufacturing a mold and the method of manufacturing an optical element are for this purpose characterized in that the mould is manufactured from a ductile metal and is given the mould shape by means of a die which is provided with a die surface corresponding to a shape of the optical sub-element and which is imprinted in the mold with a predetermined force in consecutive positions in accordance with the pattern. Said die is imprinted in the mould in consecutive positions in accordance with the pattern, i.e. a number of times which corresponds to the number of sub-elements of the optical element. This means that a die surface corresponding to the optical sub-element need be made only once in an accurate manner in the manufacture of the die. Since the time required for making a replica of the die in the mould is very short compared with the time necessary for making a die surface corresponding to the optical sub-element, the methods according to the invention can be implemented in a comparatively short time. The die required has a comparatively simple construction and can be positioned relative to the mould in the consecutive positions in accordance with said pattern by means of a positioning device which is usual and known per se. Since the die is imprinted in the mould with a predetermined force each time, the consecutive sub-shapes of the mould shape corresponding to the individual optical sub-elements have substantially identical shapes. It is achieved through a suitable choice of the force with which the die is imprinted in the mould that the ductile metal of the mould is plastically deformed exclusively at the area of the contact surface between mould and die, while the deformation around the contact surface is negligibly small, so that a sub-shape already provided in the mould and corresponding to an optical sub-element is not deformed any more upon the formation of an adjoining sub-shape. Since the sub-shape is imprinted is imprinted in the mold one at a time in consecutive positions in accordance with the pattern, it is in addition achieved that the ductile metal adjoining the die surface is optimally deformed each time, so that sharp boundaries between the sub-shapes are formed. The mould thus manufactured accordingly has a particularly high dimensional accuracy, while the optical elements manufactured by means of the mould have a high dimensional accuracy and a comparatively large optically useful surface area.
A special embodiment of a method according to the invention is characterized in that the mould is given the mould shape by means of the die after the mould has been previously provided with a surface smoothness desired for the optical element. The ductile metal is plastically deformed during the manufacture of the mould shape, for which the die is imprinted in the mould each time with the predetermined force, but a surface smoothness of the ductile metal present before deformation is substantially maintained. If the mould is first provided with a surface smoothness of an optical quality desired for the optical element, and is subsequently given the mould shape by means of the die, the mould shape and the optical elements manufactured by means of the mould will have the desired surface smoothness.
A further embodiment of a method according to the invention is characterized in that the mould is immersed in a liquid bath during the application of the mould shape by means of the die. The immersion of the mould in a liquid bath prevents in a simple and effective manner that dust and dirt particles present in the air enter between the die and the mould and damage the mould shape to be manufactured by means of the die.
A yet further embodiment of a method according to the invention is characterized in that the ductile metal comprises copper, aluminium, or zinc. These metals are eminently suitable for use in the methods according to the invention thanks to their good deformability.
A particular embodiment of a method according to the invention is characterized in that the die is provided with a spherical die surface and is imprinted in the mould in accordance with a hexagonal pattern. The optical element manufactured by this embodiment of the method has a two-dimensional hexagonal matrix of spherical lenses which have a substantially unlimited optically useful surface area.
A further embodiment of a method according to the invention is characterized in that the die has a flat die surface and is imprinted in the mould in accordance with an orthogonal pattern, while the die is pivoted through predetermined angles about two mutually perpendicular pivot axes in the consecutive positions of the pattern, which axes intersect one another in a centre of the die surface. The optical element manufactured by this embodiment of the method is a so-called faceted lens which comprises a two-dimensional orthogonal matrix of facets, each facet of the faceted lens having a flat lens surface which has been pivoted relative to a reference plane of the faceted lens about two mutually perpendicular pivot axes which extend parallel to the reference plane. The angles through which the die is pivoted in the consecutive positions of the pattern are determined beforehand, so that faceted lenses whose corresponding facets have different pivot angles can be manufactured by means of this embodiment of the method.
A device for implementing a method according to the invention the device is provided with a workpiece holder for fastening the mould, a tool holder for fastening the die, and a positioning device, the tool holder being provided with a straight guide which is displaceable relative to the workpiece holder by means of the positioning device, and with a die holder which slides relative to the straight guide and which rests against a stop of the straight guide under the influence of a predetermined elastic pretensioning force. The die is placed in the consecutive positions relative to the mould in accordance with the pattern by means of the positioning device and imprinted in the mould. When the die is moved into a next position by the positioning device, the die holder rests against the stop, and is released from this stop and exerts a force on the die and the mould corresponding to the elastic pretensioning force when the die is imprinted in the mould by means of the positioning device. The elastic pretensioning force is provided, for example, by a mechanical spring. It is achieved through a suitable choice of the elasticity modulus of the mechanical spring that the force with which the die is imprinted in the mould is substantially independent of the position occupied by the die holder in a direction parallel to the imprinting direction. This force thus has an accurately defined value, so that the mould shape is achieved in an accurate manner.
A special embodiment of a device for implementing a method according to the invention, in which the die is pivoted through predetermined angles about two mutually perpendicular pivot axes in the consecutive positions of the patter, is characterized in that the die holder is provided with a first carrier which slides relative to the straight guide, a second carrier which is pivotable relative to a pivot guide of the first carrier, and a third carrier which is pivotable relative to a pivot guide of the second carrier, while the die can be fastened to the third carrier and the two mutually perpendicular pivot axes form virtual axes of the pivot guide of the first carrier and of the pivot guide of the second carrier, respectively. The use of the two pivot guides renders it possible to set the angles through which the die is pivoted about the two pivot axes independently. Two actuators which are usual and known per se, for example, may be used in the device for setting said angles.
A liquid crystal display panel in which the properties of the optical element used therein and manufactured by a method according to the invention are used to particularly good purpose is characterized in that the optical element is a microlens array, and the display panel is provided with a liquid crystal layer which comprises a pattern of picture display elements and which adjoins the microlens array at a side where the light is incident, while each optical sub-element of the microlens array corresponds to one of the picture display elements of the liquid crystal layer.
A picture display device in which the properties of the optical element used therein and manufactured by a method according to the invention are used to particularly good purpose is characterized in that the optical element is a microlens array, while the picture display unit is provided with, in that order, an optical radiation source, a beam-forming optical system, a picture display system with at least one picture display panel, a system of projection lenses, and a picture projection screen, the picture display panel being provided with the microlens array at a side which faces the radiation source.
A flat panel display device in which the properties of the optical element used therein and manufactured by a method according to the invention are used to particularly good effect is characterized in that the optical element is a microlens array, while the flat panel display device is provided with, in that order, an illumination system for supplying an illumination beam, a picture display panel with a defined pattern of picture display elements for modulating picture information to be displayed, the microlens array being arranged between the illumination system and the picture display panel and being provided with a pattern of optical sub-elements which corresponds to the pattern of picture display elements of the picture display panel. Such a flat panel display device (back-light display) provided with a microlens array which is known per se is known from, for example, the article "Developers Cultivate TFT LCDs Specifically for Notebook Computers" by Sakae Arai in Display Devices, Spring 1994, no. 9, pp. 14–17.
The picture display panel used in the above picture display device and flat panel display device is, for example, a liquid crystal display or LCD as mentioned above. Such display panels have a large number of picture display elements or pixels which are arranged in a two-dimensional array and are separately adjustable. The individual pixels each have an electronic adjustment element whereby the optically useful surface area of the pixels is limited. The microlens array, in which each optical sub-element of the microlens array corresponds to one of the pixels of the display panel, focuses the light incident on the display panel onto the optically useful surface area of each individual pixel. Since the microlens array manufactured by the method according to the invention has a comparatively large optically useful surface area, the light beam coming from the beam-forming optical system is substantially entirely focused into the optically useful portions of the individual pixels, so that the display device has a particularly high light output. It is noted that the display panel used in the display device may alternatively be, for example, a digital micromirrored device or DMD, which is known per se.
A solid state image sensor device in which the properties of the optical element used therein and manufactured by a method according to the invention are used to particularly good effect is characterized in that the optical element is a microlens array and the image sensor device comprises a semiconductor body which is provided at a surface with a charge coupled device and with a pattern of image sensor elements for converting radiation into electric charges and which adjoins the microlens array at a side where the radiation is incident, while each optical sub-element of the microlens array corresponds to an image sensor element of the semiconductor body.
A camera in which the properties of the optical element used therein and manufactured by a method according to the invention are used to particularly good effect is characterized in that the optical element is a microlens array, and the camera is provided with, in that order, an objective lens system and an image sensor system with at least one solid state image sensor device which is provided with the microlens array at a side which faces the objective lens system.
The solid state image sensor device used in the camera has a large number of image sensor elements which are arranged in a two-dimensional array. The optically useful surface area of the solid state image sensor device is limited by the presence of the charge coupled device or CCD by means of which the electric charges generated by the image sensor elements are transported. The microlens array, in which each optical sub-element of the microlens array corresponds to one of the image sensor elements of the image sensor device, focuses the light incident on the image sensor device onto the optically useful surface areas of the individual image sensor elements. Since the microlens array manufactured by the method according to the invention has a comparatively large optically useful surface area, the light originating from the objective lens system is focused substantially entirely onto the optically useful portions of the individual image sensor elements, so that the solid state image sensor device has a particularly high light sensitivity.
A method of manufacturing a front panel for a colour picture tube in which the properties of the optical element used therein and manufactured by a method according to the invention are used to particularly good effect is characterized in that an inside of the front panel is provided with a layer of photosensitive material, and in that the front panel is subsequently illuminated through a shadow mask positioned at the inside of the front panel by means of a point-shaped light source, while the optical element is positioned between the shadow mask and the light source.
A device for manufacturing a front panel for a colour picture tube in which the properties of the optical element used therein and manufactured by a method according to the invention are used to particularly good effect is characterized in that the device is provided with, in that order, a point-shaped light source, a first holder for the optical element, and a second holder for the front panel and for a shadow mask to be arranged at an inside of the front panel.
Illumination of the photosensitive material on the front panel by means of the point-shaped light source through the shadow mask and subsequent development of the illuminated material forms a so-called symmetrical black matrix on the inside of the front panel with openings in which a phosphor is deposited during subsequent manufacturing steps of the picture tube. The optical element used is a faceted lens which comprises a two-dimensional orthogonal array of facets. The use of the faceted lens achieves that the projections of the light source formed by the shadow mask on the front panel coincide with the meeting points of the electron beams which are formed on the front panel by the shadow mask in the colour picture tube designed for the front panel and shadow mask. Such a method of manufacturing front panels for colour picture tubes is known, for example, from EP-A-0 294 867. When the faceted lens used is manufactured by a method according to the invention, this lens will have a particularly small pitch between individual facets, so that also discontinuities in the faceted lens formed by the boundaries between individual facets are particularly small. A very even illumination of the front panel is achieved thanks to the comparatively small discontinuities.
The device 1 for implementing a method according to the invention as shown in FIGS. 1 and 2 comprises a workpiece holder 3 with a support surface 5 which extends parallel to an X-direction and to a Y-direction perpendicular to the X-direction, and on which a mould 7 to be manufactured can be placed and fastened by clamping means 9 diagrammatically shown in FIG. 2. The device 1 further comprises a positioning device 11 diagrammatically shown in FIGS. 1 and 2 with a straight guide 13 extending parallel to the X-direction and an X-slide 15. The X-slide 15 is displaceable along the straight guide 13 by means of a spindle 17 which can be driven by an electric motor 21 via a transmission 19. The spindle 17 is journalled relative to a frame 23 of the device 1, and the electric motor 21 is fastened to the frame 23. The X-slide 15 is provided with a straight guide 25 extending parallel to the Y-direction along which a Y-slide 27 is displaceable by means of a spindle 29 which can be driven by an electric motor 33 via a transmission 31. The spindle 29 is journalled relative to the X-slide 15, and the electric motor 33 is fastened to the X-slide 15. As FIG. 2 shows, the Y-slide 27 is provided with a straight guide 35 which extends parallel to a Z-direction which is perpendicular to the X-direction and to the Y-direction. A Z-slide 37 is displaceable along the straight guide 35 by means of a spindle 39 which can be driven by an electric motor 43 via a transmission 41. The spindle 39 is journalled relative to the Y-slide 27, and the electric motor 43 is fastened to the Y-slide 27. It is noted that only the transmission 41 and the electric motor 43 of the Z-slide 37 are visible in FIG. 1.
As FIG. 2 further shows, a tool holder 45 is fastened to the Z-slide 37, which holder is provided with a circular-cylindrical stepped chamber 47 with a centreline 49 which extends parallel to the Z-direction. The stepped chamber 47 comprises a first chamber portion 51 and a second chamber portion 53 which has a smaller diameter than the first chamber portion 51. The second chamber portion 53 constitutes a straight guide for a round shaft 55 of a die holder 57 which slides parallel to the Z-direction relative to the second chamber portion 53 and is provided with an end disc 59. The end disc 59 bears on a stop 63, formed by a shoulder of the stepped chamber 47, under the influence of a previously defined pretensioning force of a mechanical helical spring 61 arranged in the first chamber portion 51. As FIG. 2 further shows, a die 65 is fastened to the die holder 57, with a smooth spherical die surface 67 and manufactured from, for example, a hard steel or sapphire. The tool holder 45 and the die holder 57 are jointly displaceable relative to the workpiece holder 3 in directions parallel to the X-direction, Y-direction and Z-direction by means of the positioning device 11.
The mould 7 is shown in detail in FIGS. 4a, 4b and 4c and is manufactured by the device 1 in accordance with a method to be described in more detail below. The mould 7 is designed for the manufacture of optical elements which are provided with mutually adjoining optical sub-elements arranged relative to one another in a pattern such as, for example, so-called lens arrays or so-called faceted lenses. FIGS. 5a and 5b show an example of such a lens array 69. The optical sub-elements of the lens array 69 are spherical lenses 71 provided at one side 73 of the lens array 69 in accordance with a two-dimensional hexagonal array. As FIG. 5b shows, the lens array 69 is provided with a plane surface 75 at the other side. The lens array 69 is manufactured by means of the mould 7 by a replication technique which is usual and known per se such as, for example, a replication technique whereby the mould 7 is filled with a liquid synthetic resin which cures under the influence of ultraviolet radiation, the mould 7 being subsequently covered with a plate 77 shown in FIGS. 4b and 4c and manufactured from a transparent synthetic material with a refractive index corresponding to the refractive index of the synthetic resin in the mould 7. It is noted that FIG. 4a only shows an outline of the plate 77 with a broken line. The synthetic resin in the mould 7 is cured in that it is exposed to ultraviolet radiation through the transparent plate 77, and the lens array 69 shown in FIGS. 5a and 5b is formed, built up from said transparent plate 77 and the array of optical sub-elements 71 formed by means of the mould 7.
The mould 7 is manufactured from a ductile metal such as, for example, copper, aluminium, zinc, or an alloy comprising these metals. As FIG. 4a shows, the mould 7 comprises a mould chamber 79 with a plane bottom 81 in which a mould shape 83 is provided by the device 1 in accordance with the method, so as to correspond to the pattern of sub-elements 71 of the optical element 69 to be manufactured. It is noted that FIG. 4a shows only a few parts of the mould shape 83 for simplity's sake. According to the method, the bottom 81 of the mould chamber 79 is first given a surface smoothness of optical quality desired for the optical element 69 in a manner usual and known per se, for example, by means of a diamond milling tool.
The mould 7 is subsequently fastened to the tool holder 3 of the device 1 such that the bottom 81 of the mould chamber 79 extends parallel to the X-direction and Y-direction. The spherical die surface 67 of the die 65 corresponds to one optical sub-element, i.e. a single spherical lens 71 of the optical element 69 to be manufactured. According to the method, the mould shape 83 in the bottom 81 of the mould chamber 79 is provided in that the die 65 is displaced into consecutive positions on the bottom 81 by means of the positioning device 11 in accordance with the hexagonal pattern of sub-elements 71 of the optical element 69 to be manufactured, the die 65 being imprinted in the bottom 81 in each position. The imprinting process of the die 65 is shown in detail in FIG. 3. After the die 65 has been displaced into a next position through a displacement of the X-slide 15 and/or the Y-slide 27, during which the die holder 57 rests against the stop 63 of the chamber 47, the die 65 is pressed into the bottom 81 through a displacement of the Z-slide 37. As FIG. 3 shows, the end disc 59 of the die holder 57 then clears the stop 63, so that the die 65 is imprinted in the bottom 81 with a force which corresponds to the predetermined pretensioning force of the mechanical helical spring 61. It is achieved through a favourable choice of the pretensioning force and of the elasticity modulus of the helical spring 61 that the increase in the pretensioning force of the helical spring 61 upon clearance of the end disc 59 is negligibly small, so that the force with which the die 65 is imprinted in the bottom 81 is substantially independent of the position occupied by the Z-slide 37 and the tool holder 45 parallel to the Z-direction during imprinting. No stringent requirements need accordingly be imposed on the positioning accuracy of the Z-slide 37.
While the die 65 is being imprinted in the bottom 81 of the mould 7, the ductile metal of the mould 7 present below the die surface 67 is plastically deformed, so that said metal assumes a shape corresponding to that of the die surface 67, i.e. to an optical sub-element 71 of the optical element 69. The complete mould shape 83 is formed in the bottom 81 in that the die 65 is imprinted repeatedly in consecutive positions in accordance with the pattern of the optical element 69.
It is noted that a suitable choice of the force with which the die 65 is imprinted in the mould 7 achieves that the ductile metal of the mould 7 is plastically deformed exclusively in the immediate vicinity of the contact surface between the die 65 and the bottom 81. The plastic deformation at some distance from said contact surface is found to be negligibly small, so that a portion of the mould shape 83 adjoining the contact surface and already formed in the mould 7 is not deformed again upon imprinting of the current shape corresponding to the sub-element. It is assumed that the negligibly small deformation at some distance from the contact surface can be explained from the fact that the ductile metal of the mould 7 has a polycrystalline structure, with cavities present between the individual crystals. When a comparatively small force is exerted on the surface of the ductile metal, no shearing takes place between the crystals and inside the lattices, and only the cavities present between the crystals are made smaller through compression of the ductile metal present below the die 65. Since no shearing takes place, there will be no plastic deformation of the portion of the mould shape 83 already formed. If shearing should take place between the crystals and in the lattices in the case of stronger forces, so that a plastic deformation occurs of the metal present at some distance from the die 65, this deformation will be comparatively small because the quantity of metal to be displaced is comparatively small in view of the comparatively small impression depths of the spherical die surface 67 and because the metal to be displaced is spread over a comparatively large volume.
The mould 7 shown in FIGS. 4a, 4b, 4c and used for the manufacture of the lens array 69 shown in FIG. 5a has a two-dimensional hexagonal array of spherical imprints 85. The pitch s of the adjoining imprints shown in FIGS. 4b and 4c is approximately 0.15 mm in the example shown, while the impression depth d shown in FIGS. 4b and 4c is approximately 6 μm. Such an array is formed by means of a spherical die surface 67 with a radius of approximately 0.5 mm and a pretensioning force of approximately 10 N. Since the die surface 67 corresponds to a single optical sub-element 71 of the optical element 69, the ductile metal can flow optimally around the die surface 67 upon each impression of the die 65, so that particularly sharp boundaries 87 are formed between the individual imprints 85 forming the mould shape 83. As FIGS. 4b and 4c show, the boundaries 87 between the imprints 85 of the mould 7 each form part of a circle, i.e. the boundaries 87 each correspond to a portion of a parallel of latitude of the spherical die surface 65. The mould 7 thus has a particularly high dimensional accuracy, i.e. substantially all points on the surface of the mould shape 83 form part of the spherical surface of one of the imprints 85. The optical elements 69 to be manufactured by means of the mould 7 as a result have a particularly large useful optical surface, i.e. substantially all points at the side 73 of the optical element 69 form part of the spherical surface of one of the optical sub-elements 71.
The lens matrix 69 shown in FIGS. 5a and 5b and manufactured with mould 7 is a so-called microlens array. Such a microlens array comprises a large number of microlenses with a diameter smaller than, for example, 1 mm. Since the die surface 67 of the die 65 used corresponds to only one optical sub-element, i.e. one microlens 71 of the lens array 69, the die 65 can be manufactured in a simple manner. It was found in practice that the surface smoothness of the bottom 81 of the mould 7 is not affected by the imprinting process of the die 65 in the bottom 81 of the mould 7. Since the bottom 81 is first provided with the desired surface smoothness according to the invention and is then given the mould shape 83 by the die 65, the desired surface smoothness is achieved in a comparatively simple manner.
While the mould shape 83 is being provided, the presence of dust and dirt particles between the bottom 81 of the mould 7 and the die surface 67 should be prevented because such dust and dirt particles can damage the mould shape 83. Providing the mould shape 83 by means of the die 65 should accordingly take place in a substantially dust-free environment such as, for example, in a conditioned space. In a special embodiment of the device 1, the tool holder 3 is arranged in a liquid bath 89, indicated with a broken line in FIG. 2 and filled, for example, with water during operation. In this special embodiment, the mould 7 is immersed in the liquid bath 89 while the mould shape 83 is being provided, whereby the presence of dust and dirt particles between the die 65 and the bottom 81 of the mould 7 is prevented in a simple and effective manner.
FIGS. 6 and 7 diagrammatically show a tool holder 91 and a die holder 93 of an alternative embodiment of a device 95 for carrying out a method according to the invention. The tool holder 91 is substantially identical to the tool holder 45 of the device 1, and corresponding parts of the tool holders 45 and 91 and of the devices 1 and 95 are given the same reference numerals below. Like the die holder 57, the die holder 93 has a round shaft 97 which slides in the second chamber portion 53 of the tool holder 91 and an end disc 99 which bears against the stop 63 of the stepped chamber 47 under the influence of a predetermined pretensioning force of a mechanical helical spring 101 arranged in the first chamber portion 51. The round shaft 97 and the end disc 99 belong to a first, furcate carrier 103 of the die holder 93. As FIGS. 6 and 7 show, the first carrier 103 comprises two circular pivot guides 105, 107 for a second carrier 109 of the die holder 93 which is provided with two circular slots 111, 113 for cooperating with the pivot guides 105, 107. The second carrier 109 is pivotable relative to the first carrier 103 about a first virtual pivot axis 115 of the pivot guides 105, 107, which is directed parallel to the X-direction, through the use of pivot guides 105, 107. As FIGS. 6 and 7 further show, the second carrier 109 comprises two circular pivot guides 117, 119 for a third carrier 121 of the die holder 93 which is provided with two circular slots 123, 125 for cooperating with the pivot guides 117, 119. The third carrier 121 is pivotable relative to the second carrier 109 about a second virtual pivot axis 127 of the pivot guides 117, 119, which is directed parallel to the Y-direction and intersects the first virtual pivot axis 115, through the use of pivot guides 117, 119. A die 129 is fastened to the third carrier 121 and is provided with a plane, rectangular die surface 131. In a neutral position of the second carrier 109 relative to the first carrier 103 and of the third carrier 121 relative to the second carrier 109, the die surface 131 extends parallel to the X-direction and the Y-direction, while the point of intersection of the first virtual pivot axis 115 and the second virtual pivot axis 127 is situated in a centre M of the die surface 131.
As FIGS. 6 and 7 further show, a first linear electrical actuator 133, which is usual and known per se, is fastened to the first carrier 103, an output shaft 135 of the actuator being coupled to a coupling rod 137 fastened to the second carrier 109. A second linear electrical actuator 139 identical to the first actuator 133 is fastened to the second carrier 109 and has an output shaft 141 which is coupled to a coupling rod 143 fastened to the third carrier 121. A pivot angle α of the second carrier 109 about the first virtual pivot axis 115 is adjustable by means of the first actuator 133, while a pivot angle β of the third carrier 121 about the second virtual pivot axis 127 is adjustable by means of the second actuator 139. As FIGS. 6 and 7 show, the round shaft 97 of the die holder 93 is fastened to the first chamber portion 51 via an elastically deformable membrane 145, so that the carriers 103, 109, and 121 and the die 129 are not rotatable about the centreline 49 of the tool holder 91.
The device 95 is used for the manufacture of a mould 147 shown in FIGS. 8a, 8b, 8c and designed for the manufacture of so-called faceted lenses. FIGS. 9a, 9b and 9c show an example of such a faceted lens 149. The faceted lens 149 is provided at one side with a plane surface 151 and at the other side 153 with a two-dimensional orthogonal array of rectangular optical sub-elements 155, each sub-element 155 having a plane lens surface 157 which has been pivoted about two mutually perpendicular pivot axes relative to a reference plane of the faceted lens 149 which may be, for example, the plane surface 151. The faceted lens 149 is manufactured by means of the mould 147 by a replication technique such as, for example, the replication technique described above for the manufacture of the lens array 69.
Like the mould 7, the mould 147 is made from a ductile metal, a bottom 159 of the mould 147 being first provided with a surface smoothness of optical quality as desired for the faceted lens 149. Then the mould 147 is fastened on the workpiece holder 3 of the device 95 such that the bottom 159 of the mould 147 lies parallel to the X-direction and the Y-direction. The rectangular plane die surface 131 of the die 129 corresponds to one optical sub-element 155 of the faceted lens 149. According to the method, the bottom 159 of the mould 147 is given a mould shape 161 corresponding to the faceted lens 149 by moving the die 129 into consecutive positions on the bottom 159 by the positioning device 11 of the device 95 in accordance with the orthogonal pattern of sub-elements 155 of the faceted lens 149, while pivoting the die 129 in each position about previously defined angles α and β about the virtual pivot axes 115, 127 by means of the actuators 133, 139 and subsequently imprinting in the bottom 159 with a force corresponding to the predetermined pretensioning force of the helical spring 101. The angles α and β are independently adjustable. In addition, the angles α and β may be differently adjusted for consecutive moulds to be manufactured, so that a large number of different moulds can be manufactured by means of the device 95. It is noted that FIG. 8a shows only a few portions of the mould shape 161 for simplicity's sake.
As was also noted above with reference to the device 1, the device 95 is particularly suitable for the manufacture of optical elements which comprise a comparatively large number of optical sub-elements of comparatively small dimensions. As FIGS. 9b and 9c show, the faceted lens 149 manufactured by means of the mould 147 comprises usual discontinuous boundaries 163 between the individual sub-elements 155 which cause an undesirable scattering of the light radiated through the faceted lens 149. When the faceted lens 149 is positioned, for example, between a point-shaped light source and a flat screen, irregularities in the illumination of the screen arise from scattering. Since the faceted lens 149 manufactured by means of the mold 147 has a comparatively large number of sub-elements 155 each of comparatively small dimensions (for example, 1 mm or smaller), the discontinuous boundaries 163 have comparatively small dimensions so that irregularities are comparatively small and an even illumination of the screen is provided.
FIG. 10a diagrammatically shows a picture display device 169 comprising a microlens array 171 manufactured by a method according to the invention. Such a picture display device provided with a microlens array which is known per se is known from, for example, EP-A-0 574 269. The picture display device 169 comprises an optical radiation source 173 and a reflector 175. The light radiated by the radiation source 173 is shaped into a parallel light beam 177 by means of a converging optical system represented in FIG. 10a as a single condenser lens 179 for simplity's sake. The picture display device 169 further comprises a picture display system such as, for example, a liquid crystal display panel 181 diagrammatically shown in FIG. 10a. The display panel 181 is provided with a liquid crystal layer 183 which is usual and known per se and which comprises a two-dimensional orthogonal array of picture display elements or pixels 185. It is noted that only a lateral edge of the liquid crystal layer 183 is visible in FIG. 10a. As FIG. 10b shows, the pixels 185 each comprise an optically useful portion 187 surrounded by an electronic switching element 189 which is shown diagrammatically only and by means of which the optically useful portion 187 of the pixel 185 is separately optically adjustable. As FIG. 10b shows, the optically useful portion 187 of each pixel 185 is limited to a central portion of the pixel 185 by the presence of the switching element 189. As FIG. 10a shows, the liquid crystal display panel 181 is provided with the microlens array 171 mentioned above at a side 191 of the liquid crystal layer 183 where the light is incident. As FIG. 10c shows, the microlens array 171 comprises a two-dimensional orthogonal matrix of spherical microlenses 193 wherein each microlens 193 corresponds to one of the pixels 185 of the liquid crystal layer 183. The microlens array 171 focuses the parallel light beam 177 onto the optically useful surfaces 187 of the individual pixels 185 of the liquid crystal layer 183. As FIG. 10a shows, the picture display device 169 further comprises a field lens 195 by means of which the light originating from the display panel 181 is converged towards a projection lens system which is represented as a single projection lens 197 for simplicity's sake, and a projection screen 199. Since the microlens array 171 was manufactured by a method according to the invention, the microlens array 171 has a particularly large useful optical surface, so that the parallel light beam 177 is scattered to a very limited degree only and is focused substantially completely onto the optically useful surfaces 187 of the individual pixels 185 of the liquid crystal layer 183. The picture display device 169 accordingly has a particularly great light output.
FIG. 11a diagrammatically shows a camera 201 provided with a microlens array 203 manufactured by a method according to the invention. The camera 201 comprises an objective lens system which is represented as a single objective lens 205 in FIG. 11a for simplicity's sake. The camera 201 further comprises an image sensor system with a solid state image sensor device 207 diagrammatically shown in FIG. 11a and provided with the microlens array 203 at a side which faces the objective lens 205. It is noted that lateral edges of the microlens array 203 and of the solid state image sensor device 207 are visible only in FIG. 11a. The solid state image sensor device 207 is diagrammatically shown in FIG. 11b. Such a solid state image sensor device of the IT type (Interline Type) provided with a microlens array known per se is disclosed in, for example, JP-A-1-257901. As FIG. 11b shows, the solid state image sensor device 207 comprises a semiconductor body 209 which is provided at a surface 211 with a two-dimensional orthogonal array of image sensor elements or photodiodes 213 for converting radiation into electric charges which can be transported to an electronic read-out unit 218 shown diagrammatically only in FIG. 11b through a system of so-called vertical charge coupled devices 215 and a horizontal charge coupled device 217. The charge coupled devices 215, 217 are shielded against radiation by a protective layer of, for example, aluminum. As is apparent from FIG. 11b, the optically useful surface area of the solid state image sensor device 207 is limited to the areas of the photodiodes 213. The microlens array 203, which is not shown in FIG. 11b for the sake of clarity, comprises a two-dimensional orthogonal array of spherical microlenses 219 corresponding to the microlens array 171 shown in FIG. 10c, each microlens 219 corresponding to one of the photodiodes 213 of the solid state image sensor device 207. The microlens array 203 at the light incidence side of the solid state image sensor device 207 focuses the light incident on the solid state image sensor device 207 through the objective lens 205 onto the optically useful surfaces of the individual photodiodes 213. Since the microlens array 203 was manufactured by a method according to the invention, the microlens array 203 has a particularly large useful optical surface area, so that the light incident on the solid state image sensor device 207 is scattered to a very limited degree only and is substantially completely focused onto the optically useful surface areas of the individual photodiodes 213. The camera 201 and the solid state image sensor device 207 used therein accordingly have a particularly high photosensitivity. It is noted that a microlens array manufactured by the method according to the invention is also applicable in a solid state image sensor device of the FT type (Frame Transfer type), in which the charge coupled devices used are themselves provided with the required image sensor elements, and in, for example, "still-picture" image sensor devices.
FIG. 12 diagrammatically shows a device 221 for manufacturing a front panel 223 for a color picture tube. The device 221 is provided with a faceted lens 225 manufactured by a method according to the invention. Such a device provided with a faceted lens known per se is known, for example, from EP-A-0 294 867 (=U.S. Pat. No. 4,866,466). As FIG. 12 shows, the device 221 comprises a housing 227 with a bottom 229 on which a point-shaped light source 231 is centrally positioned. A first holder 233 for the faceted lens 225 and a second holder 235 for the front panel 223 to be manufactured by means of the device 221 are further present in the housing 227. As FIG. 12 shows, a shadow mask 239 belonging to the front panel 223 is also arranged on the second holder 235 at an inside 237 of the front panel 223. The shadow mask 239 is in a position relative to the front panel 223 which corresponds to a position occupied by the shadow mask 239 relative to the front panel 223 in a color picture tube which is to incorporate the front panel 223 and the shadow mask 239.
The inside 237 of the front panel 223 is provided with a so-called symmetrical black matrix, in which openings are present, by means of the device 221. A phosphor will be deposited in the openings of the black matrix during subsequent steps in the manufacture of the front panel 223, so that the latter is provided with the required phosphor dots. The inside 237 of the front panel 223 is for this purpose first provided with a layer of photosensitive material such as, for example, a positive photoresist which is usual and known per se. Then the photosensitive material on the front panel 223 is exposed through the shadow mask 239 by means of the device 221, after which the exposed material is developed with a developer liquid. Since the openings in the black matrix to be formed in this way must coincide with the points of incidence of the electron beams formed in the relevant color picture tube by the shadow mask 239, and since the electron beams in the relevant color picture tube in general follow curved paths, the light of the light source 231 must so be deflected by means of the faceted lens 225 that the projections of the light source 231 formed by the shadow mask 239 on the front panel 223 coincide with the points of incidence of the electron beams. The faceted lens 225 for this purpose has a two-dimensional orthogonal array of rectangular plane facets 241 corresponding to the faceted lens arrangement 149 shown in FIG. 9a, which facets have all been pivoted about two mutually perpendicular pivot axes which extend parallel to the surface 151 of the faceted lens 225 through angles whose values follow from paths of the electron beams. As was discussed above with reference to the faceted lens 149 shown in FIGS. 9a, 9b, 9c, the faceted lens 225 manufactured by the method according to the invention has a comparatively large number of sub-elements 241 of comparatively small dimensions, so that the light from the light source 231 incident on the faceted lens 225 is scattered to a very limited degree only and a particularly even illumination of the front panel 223 by the faceted lens 225 is achieved.
The optical elements 69, 149, 171, 203, 225 mentioned above all have regular patterns of optical sub-elements 71, 155, 193, 219, 241, the optical sub-elements 71, 193 and 219 of the optical elements 69, 171 and 203 being identical to one another. It is noted that it is also possible to manufacture optical elements with optical sub-elements which are not identical by means of the method according to the invention. Among the examples mentioned above were the faceted lenses 149, 225 whose facets 155, 241 were pivoted about mutually different angles. According to the method, however, lens arrays may also be manufactured which are provided with mutually differing lenses. To achieve this, however, a number of different dies must be used corresponding to the number of different lenses in the lens array to be manufactured. In addition, the method allows for the manufacture of optical elements wherein the optical sub-elements are arranged in a different pattern, wherein the optical sub-elements are arranged in an irregular pattern, or wherein a different type of sub-element is used. It is also possible to manufacture optical elements by the method wherein the optical sub-elements are not convex, concave, or flat lenses, as in the lens matrices 69, 171, 203 and the faceted lenses 149, 225, but wherein the optical sub-elements are, for example, plane, convex, or concave mirrors.
The dies 65, 129 mentioned above have die surfaces 67, 131 each corresponding to a single optical sub-element 71, 155, 193, 219, 241 of the optical elements 69, 149, 171, 203, 225 to be manufactured. It is noted that it is also possible to use a die provided with a die surface corresponding to two or more optical sub-elements of the optical element to be manufactured. The manufacture of such a multiple, single-piece die is more time-consuming, but the provision of the shape proceeds more quickly by means of said multiple die. In addition, such a multiple die must be positioned relative to the mold with a higher accuracy in the X- and Y-directions, otherwise a deviation in the interspacings between the optical sub-elements will arise at regular intervals, which leads to an optical deviation of the optical element to be manufactured. When a single die is used, this deviation in the interspacings between the optical sub-elements will arise between each pair of adjoining sub-elements, so that no regularly repeated deviation arises here.
It is further noted that instead of the replication technique described above, whereby the optical elements are manufactured from a synthetic resin material which is cured under the influence of ultraviolet radiation, an alternative replication technique may be used, for example a replication technique whereby the optical elements are manufactured from a thermosetting synthetic resin.
The molds 7, 147 described above have planar bottoms 81, 159 in which the desired mold shapes 83, 161 are provided by means of the dies 65, 129. It is noted that the mold shape may alternatively be provided in a non-planar bottom of the mold, given a positioning device for the die which is suitable for this purpose. A non-planar mold bottom may be used, for example, in the manufacture of faceted lenses in which the pivot angles of the facets have a strong gradient. The mold bottom may be provided here, for example, with a curvature corresponding to an average gradient of the pivot angles. When the facets are provided in the mold bottom thus manufactured, the die need be pivoted relative to the mold bottom locally over small angles only, so that the mold bottom is plastically deformed to a small degree only during imprinting of the die, and a plastic deformation of the adjoining facets already formed is prevented. It is also possible to manufacture an optical element by the method, for example, which is provided with a pattern of spherical lenses arranged on a spherical or aspherical basic body.
It is further noted that instead of the positioning device 11 an alternative type of positioning device may be used. Also, the device 1, 95 may be provided with a different type of die holder such as, for example, a die holder in which the predetermined impression force of the die is supplied by a hydraulic cylinder.
The picture display device 169 and camera 201 shown diagrammatically only in the Figures and discussed briefly above only comprise a single display panel 181 and only a single solid state image sensor device 207, respectively. It should finally be noted that such a picture display device and camera may alternatively comprise more than one display panel and more than one solid state image sensor device, respectively, which device and camera are each provided with a system of colour separation prisms, usual and known per se, for splitting up the light beam into a number of basic colors, while the picture display device and camera are provided with a separate display panel and a separate solid state image sensor device, respectively, for each color.

Method of manufacturing a mold for use in the manufacture of an optical element comprising optical sub-elements mutually arranged in a pattern, and device for implementing such a method


Certain exemplary embodiments comprise a breaker interlock device adapted to mechanically resist switching a handle of a first circuit breaker from an OFF position to an ON position when a handle of a second circuit breaker is in an ON position, wherein the first circuit breaker is adjacent to the second circuit breaker.

United States Patent Application No. 20040045796 (Azzola), which is incorporated by reference herein in its entirety, allegedly recites a "device for interlocking at least two single- or multipole circuit breakers, of which:—a first circuit breaker, suitable to be fixed to a mounting plate of the first and second circuit breakers;—a second circuit breaker, suitable to be fixed by virtue of fixing means to the first bracket and to be supported thereby;—an interlocking element, provided with a contoured body that is operatively coupled to the second bracket so that it can move with respect to it, the interlocking element being suitable to be rigidly connected to the second bracket, by virtue of locking means, in a chosen position in which it interacts operatively with at least the first opening/closure lever in a condition that corresponds to the opening of the first circuit breaker, preventing its movement and preventing the circuit breakers from being closed simultaneously." See Abstract.
U.S. Pat. No. 4,924,041 (Yee), which is incorporated by reference herein in its entirety, allegedly recites a "universal circuit breaker interlock arrangement allows two circuit breakers to be interlocked such that only one of the circuit breakers is on at one time. The circuit breakers can be interlocked, per se, or when used with an electrical motor operator or with a manual rotary operator. The slidably mounted interlock arrangement also allows interlock function between two electric switches as well as between an electric switch." See Abstract.
U.S. Pat. No. 5,763,844 (Seymour), which is incorporated by reference herein in its entirety, allegedly recites a "circuit breaker interlock arrangement of the invention utilizes a pair of detector assemblies, one mounted on the rear surface of each one of a pair of first and second adjoining circuit breakers and interconnected by means of an elongated rod. The operating mechanism tripping plunger rod in the first circuit breaker trips the associated first circuit breaker operating mechanism to open the first circuit breaker contacts when an attempt is made to close the first circuit breaker contacts when the second circuit breaker contacts in the second circuit breaker are already closed, and vice versa." See Abstract.

Circuit breaker interlock devices, systems, and methods


Methods and apparatus for providing a projection system. In one embodiment, the system provides plurality of light sources collimating light using a parabolic concentrator. The system may direct light from a plurality of light sources towards a light collector which directs light towards a fresnel lens which directs light to a polarizing recombiner. The system may also usiethe recombiner to allow light having a first polarization to pass. The recombiner to convert light of a second polarization to light having the first polarization and letting converted light pass to an LCD image panel. In another embodiment, a projection system having a light source capable of achieving a bright, homogenized output is disclosed. The present invention provides such a projection system through at least two embodiments. The first projection system may use a cubic projection system. The second may use a conical projection system.

The present invention relates to projection systems. More particularly, some embodiments of the present invention relate to a projection system having uniform, bright, homogenized output.
Projection systems have been known for some time. Cinema projectors until recently have all been based on analog technology. Historically, Thomas Edison invented a device called the "kinescope", which passed a light through a transparent medium. This device used an electric arc lamp to produce the light required for projection. Because of the size of the arc gap, significant amounts of light were lost and only a very small percentage was usable for the projected image. Modern advancements were mostly mechanical in nature, the film was perforated, mechanisms were designed to carry the film reel in front of the light etc . . . . The nature of the light source, however, did not change until the invention of the Xenon bulb, which is a high pressure glass container with the electrodes inside the glass cavity. Xenon bulbs for cinema today vary in watts depending on the screen size. They range from 2500 watts to 15,000 watts. Their efficiency was greater than the metallic arc lamps as well as a longer life, sometimes as long as 1000 hours. But like the metallic arc, the gap between the electrodes is still quiet wide at 7 to 10 mm. This gap is especially important when one is using a small (less than an inch) imager. The physical principle that limits the amount of usable light is the "optical invariant" or "etendu", which is based on the acceptance angle of the arc gap/reflector relationship to the image plane. The smaller the gap the more light can be captured for the projection imager. All the current digital cinema projectors (TI, JVC, Kodak) use this approach with the xenon arc lamp reflector combination. Unfortunately they cannot over come the optical invariant and like the original Edison metallic arc and lose a significant portion of the usable light. Frequently, these systems are unable to provide a uniform, bright, homogenized output. Such a system remains wanting.
Projection systems using LCD image panels are at a further disadvantage since the LCD panel polarizes light and in do so, rejects 50% of the light that are at the wrong polarization. So immediately, those LCD panels are only half as bright as other image panels and have an additional hurdle to overcome.

Method and apparatus for a projection system


Various imaging processing techniques for displaying a pre-subpixel rendered image. The pre-subpixel rendered image can be transmitted directly to a display capable of displaying a subpixel rendered image. The pre-subpixel rendered image can also be stored for later transmission for output to the display. Additionally, the pre-subpixel rendered image can be embedded in an image data stream and later extracted and displayed.

In commonly owned U.S. patent applications: (1) United States Publication No. 2002/0015110 ("the '110 application) [Ser. No. 09/916,232] entitled "ARRANGEMENT OF COLOR PIXELS FOR FULL COLOR IMAGING DEVICES WITH SIMPLIFIED ADDRESSING," filed Jul. 25, 2001; (2) United States Publication No. 2003/0128225 ("the '225 application) [Ser. No. 10/278,353] entitled "IMPROVEMENTS TO COLOR FLAT PANEL DISPLAY SUB-PIXEL ARRANGEMENTS AND LAYOUTS FOR SUB-PIXEL RENDERING WITH INCREASED MODULATION TRANSFER FUNCTION RESPONSE," filed Oct. 22, 2002; (3) United States Publication No. 2003/0128719 ("the '719 application) [Ser. No. 10/278,352] entitled "IMPROVEMENTS TO COLOR FLAT PANEL DISPLAY SUB-PIXEL ARRANGEMENTS AND LAYOUTS FOR SUB-PIXEL RENDERING WITH SPLIT BLUE SUBPIXELS," filed Oct. 22, 2002; (4) United States Publication No. 2004/0051724 ("the '724 application) [Ser. No. 10/243,094] entitled "IMPROVED FOUR COLOR ARRANGEMENTS AND EMITTERS FOR SUBPIXEL RENDERING," filed Sep. 13, 2002; (5) United States Publication No. 2003/0117423 ("the '423 application) [Ser. No. 10/278,328] entitled "IMPROVEMENTS TO COLOR FLAT PANEL DISPLAY SUB-PIXEL ARRANGEMENTS AND LAYOUTS WITH REDUCED BLUE LUMINANCE WELL VISIBILITY," filed Oct. 22, 2002; (6) United States Publication No. 2003/0090581 ("the '581 application) [Ser. No. 10/278,393] entitled "COLOR DISPLAY HAVING HORIZONTAL SUB-PIXEL ARRANGEMENTS AND LAYOUTS," filed Oct. 22, 2002, novel subpixel arrangements are therein disclosed for improving the cost/performance curves for image display devices and herein incorporated by reference.
These improvements are particularly pronounced when coupled with subpixel rendering (SPR) systems and methods further disclosed in those applications and in commonly owned U.S. patent applications: (1) United States Publication No. 2003/0034992 ("the '992 application) [Ser. No. 10/051,612]entitled "CONVERSION OF A SUB PIXEL FORMAT DATA TO ANOTHER SUB-PIXEL DATA FORMAT," filed Jan. 16, 2002; (2) United States Publication No. 2003/0103058 ("the '058 application) [Ser. No. 10/150,355] entitled "METHODS AND SYSTEMS FOR SUB-PIXEL RENDERING WITH GAMMA ADJUSTMENT," filed May 17, 2002; (3) United States Publication No. 2003/0085906 ("the '906 application) [Ser. No. 10/215,843] entitled "METHODS AND SYSTEMS FOR SUB-PIXEL RENDERING WITH ADAPTIVE FILTERING," filed Aug. 8, 2002. The above-referenced and commonly owned applications are hereby incorporated herein by reference.

Image data set with embedded pre-subpixel rendered image


An integrated circuit for analog to digital conversion using a plurality of unit capacitors (201). The value of each unit capacitor (201) has a nonlinear spatial component determined by the location of the unit capacitor (201) on the integrated circuit. A plurality of array capacitors (101a-101e) are formed from the unit capacitors (201) such that each array capacitor (101a-101e) includes a selected group of unit capacitors (201). The unit capacitors (201) that make up each array capacitor (101a-101e) are selected based upon the nonlinear spatial component in the unit capacitance value.

1. Field of the Invention
The present invention relates, in general, to layout and arrangement of components on a semiconductor chip, and, more particularly, to arrangement of capacitors for precision matching in an integrated circuit.
2. Relevant Background
Because capacitors are easily implemented in MOS fabrication technology, capacitors rather than resistors are used as the precision components in many analog-to-digital converters (ADCs) and digital-to-analog converters (DACs). A plurality of capacitors are used as the precision elements in an array. A technique referred to as "charge redistribution" is used to operate ADCs and DACs using capacitors as the storage element. The accuracy of the ADC converter using the charge redistribution technique is primarily determined by the matching of the capacitors in the array.
In a charge redistribution converter, a sample is stored dynamically with minimum loss in an array of precision matched capacitors. The sample is stored as charge that is moved from one array capacitor to another by MOSFET switches. One of the more widely used charge redistribution converter techniques is based on successive approximation. This technique primarily uses capacitors having binary weighted values with a top plate of all the capacitors connected to one input of a comparator and the bottom plates switched between various voltages. The steering of the various switches is controlled by the comparator through auxiliary logic circuitry.
The charge redistribution conversion process is begins with a sampling step followed by a charge redistribution step in which the output digital word (or "byte") is determined. In the sampling step, the top plates of the capacitors are normally connected to ground or some suitable sample reference voltage, and the bottom plates are coupled to the input voltage. This results in a stored voltage on the bottom plate that is proportional to the input voltage.
The sample step may be followed by an optional hold step in which the top plate is electrically isolated and the bottom plates are normally connected to ground or some suitable hold reference voltage. During a hold step, the charge on the top plate is conserved and the top plate potential goes to the negative of the input voltage. Because the hold step can complicate the conversion process, it is often not used.
In the conversion or redistribution step, each individual bit of the output byte is determined by sequentially connecting the bottom plates of each of the capacitors to either a redistribution reference voltage or to ground until the voltage on the top plate reaches a predetermined voltage. This is usually the trip point of the comparator.
The array is a collection of capacitors having top plates that are all connected to a comparator input node. As used herein, the term "array capacitor" means any of the capacitors used for charge redistribution and is not intended to imply that the capacitors are arranged in a grid or geometric array. Most often, a binary array is used, meaning that the ratios of the capacitors within the array are powers of 2 (i.e., C.sub.N =2C.sub.N-1 =4C.sub.N-2 =2.sup.N-1 C1). The ADC linearity is determined by the errors in these ratios.
Error mechanisms in semiconductor fabrication processes that affect these ratios include patterning and etching variations when fabricating the capacitor plates and dielectric thickness variations when fabricating the insulator layer. Other error mechanisms are known and may dominate in a particular fabrication process including variations in dielectric constant or insulator composition. The present invention addresses ADC linearity limitations that are caused by the control of the fabrication process.
To reduce factory variations, each array capacitor is formed from a plurality of small, identical "unit capacitors". In this manner, process variations that affect the periphery of a unit capacitor have a proportionate affect on each of the array capacitors. The grouping of the unit capacitors in the array mimics the desired capacitor ratios. For example, if a ratio C.sub.2 =2C.sub.1 is desired, then C.sub.2 has two capacitors identical to C.sub.1 connected in parallel. This means that a binary array of N capacitors has of 2.sup.N -1 identical unit capacitors. The capacitance of each unit capacitor is typically that of the smallest capacitor in the array.
To minimize differences between unit capacitors they are typically placed on a regular two-dimensional grid. The grid is extended one extra unit in all four directions to surround the array by a perimeter of dummy unit capacitors. The dummy unit capacitors make the local environment of all interior unit capacitors as identical as possible. In spite of this great care in array layout, the complete elimination of fabrication errors is virtually impossible.
It has been recognized that many fabrication processes have spatial variations across a wafer and across a single integrated circuit chip. These variations make precision device matching difficult. Capacitor arrays for charge redistribution ADC devices have been formed from symmetrically arranged groups of the unit capacitors to compensate for spatial parameter variation across the chip. However, it has been discovered that such groupings only compensate for linear parametric variations. Hence, certain fabrication technologies that exhibit nonlinear parametric variations have produced poor device matching when simple symmetric arrangement is used.
Although capacitors can be formed using thin film materials such as polysilicon or polycide for the electrodes, such processes are relatively expensive to add to a conventional CMOS fabrication process. Also, in conventional CMOS processes, the dielectric placed between layers of thin films is typically quite thin. Although maximizing the capacitance per unit area is often desired, the thin film capacitors resulting from a conventional CMOS flow have such high capacitance per unit area that each of the array capacitors must be physically small to provide a suitable input impedance for the ADC. However, physically small capacitors exhibit greater process variability. Hence, it would be desirable to fabricate the unit capacitors using structures that allow physically large capacitors with low capacitance per unit area.
Metal-to-metal capacitors are formed during the interconnect metallization portion of conventional CMOS processing. The metal layers are typically separated by a thick dielectric that gives them relatively low capacitance per unit area. Unfortunately, prior efforts to arrange the metal-to-metal capacitors using the same symmetrical arrangements used for polysilicon capacitors have resulted in poor matching and greater ADC linearity errors. What is needed is a capacitor arrangement and method for arranging capacitors that compensate for process variations not handled by conventional symmetrical layouts.
A great deal of effort and expense has occurred in the industry recently to develop methods and structures that correct these errors. One method uses a second binary array of capacitors that adds to the regular charged redistribution capacitor array and error correcting signal to compensate for the mismatch. This error correcting signal is then stored and the other error correcting signals for the other capacitors in the regular capacitor array are determined and subsequently stored for later correction of other capacitance mismatch.
The present invention has particular application in charge redistribution ADCs that use an array of matched capacitors. However, it should be understood that the present invention is useful in any device requiring matched performance between devices on the chip. For example, matched capacitor arrays are used in digital to analog converters and switched capacitor filters also. Moreover, other types of matched devices, such as matched resisters or matched active devices including field effect transistor or bipolar transistors, can make use of the layout method and structure in accordance with the present invention. However, for purposes of discussion the present invention will be illustrated in terms of a charge redistribution ADC only.

Weighted capacitor array with selective grouping to form array elements


A device and method for ferrofluid power generator and cooling system, wherein the waste heat of electronic device is used as a heat source to vaporize fluid and form bubbles as a forwarding pump of the ferrofluid. The fluid with magnetic nano particles is pumped forward and rotated by a fluid mechanism, then passes through a high density coil to result in the time varying magnetic flux and induced current. No additional heat-dissipating device is needed for this invention to dispose the waste heat, which requires the waste heat to produce electricity, which provides cooling and saves power.

1. Field of the Invention
The invention relates to a device and method for ferrofluid power generator and cooling system, especially to a device and method applied to a ferrofluid power generator and cooling performed by the phase change of fluid that may remove waste heat generated from an electronic device.
2. Description of the Prior Art
Since IC was invented in 1959, IC fabrication technology has advanced tremendously. It is expected that an era of nano (nm) technology will come in the 21st century. Micro electronic devices have a huge impact on companies and systems because they added chip functions within a common space causing increased heat, which is a big challenge to the engineers and researchers. It is predictable that more functions embedded in a chip, require more cooling.
For either a personal computer or notebook, cooling is always an issue. Although cooling fans are already installed on a typical computer, they increase weight, consume extra power, and are not very effective. With the increased processing speed, the computer generates more waste heat. For a CPU (central processing unit) made by either INTEL or AMD, cooling must be done effectively, or the computer will become unstable, dead, or even burnt.
A notebook computer is convenient, light, and portable, consequently, it is preferably made as small and light as possible. Therefore, an interior of the notebook is always very limited. The most power-consuming component of a typical notebook is the central processing unit (CPU). The higher the processing speed, the more power consumed by CPU. Especially for a new generation Pentium 4 processor, much more power is consumed then Pentium 3 processor or Celeron model, therefore generating more heat.
Consequently, current manufacturers of electronic devices, especially for producers of notebook, are anxious to solve this heat-dissipating problem of the electronic component. As shown in FIG. 1, the traditional way to dissipate heat is to arrange a fan 11 and heat-dissipating fin 12 on a central processing unit (CPU) 10, such that CPU waste heat is conducted to the large area of heat-dissipating fin 12, then forced convection is performed by the fan 11.
Currently, for most notebooks, a CPU-attached fan (as shown in FIG. 1) and a system fan are installed, but for notebooks with Pentium 4 CPU, this method is not only power consuming (the consuming power ranges from 1.6 W to 7.7 W, the average is around 4.5 W) but also very noisy (the level of noise is around 39 dBA). Furthermore, the poor cooling efficiency of this type of cooling fan is far from perfect (cooling efficiency is only 0.1 W/cm2) because of the limited heat-dissipation capacity of forced convection.
According to the shortcomings of aforementioned prior arts, the inventor proposes a device and method fo ferrofluid power generator and cooling system, such that the heat-dissipating problem of notebook may be resolved effectively, wherein the waste heat generated from the CPU may be applied as an energy source for power generating, such that the double effects of cooling and power saving of a notebook are achieved.

Device and method for ferrofluid power generator and cooling system

Industrial Technology Research Institute


A yarn traversing apparatus includes a first traverse member having rotary blades for traversing a yarn from a center toward ends of a traverse stroke, and a second traverse member having rotary blades for traversing the yarn from the ends toward the center of the traverse stroke in order to wind the yarn onto a bobbin to form a yarn package. Guide rails are provided so as to maintain the speed of the yarn constant as it is conveyed by the first traverse member, and to gradually decrease the speed of the yarn from the ends of the traverse stroke to the center of the traverse stroke as it is conveyed by the second traverse member, from a speed that is 1.5 to 7 times that of the first traverse member, to a speed substantially the same as that of the first traverse member.

This invention relates to a yarn traversing apparatus for obtaining a wound yarn package at a high speed winding with a good wound shape and without cob-webbing.
More specifically, the present invention relates to a yarn traversing apparatus, which comprises at least one pair of rotary blades which rotate in opposite directions and a mechanism for transferring the yarn between the blades.
Conventionally known yarn traversing apparatus of the above-described type are, for example, disclosed in Japanese Patent Publication No. Sho 53-22178, Japanese Patent Publication No. Sho 46-36258, and Japanese Patent Laid-open No. Sho 59-194977.
However, in these conventionally known apparatus, the yarn temporarily becomes free i.e., the yarn becomes in an unstable condition, when the yarn is transferred from one of the oppositely rotating yarn guides to the other yarn guide. Accordingly, there occurs a disadvantage that the obtained yarn quality is deteriorated because high shoulders are formed at ends of the package corresponding to traverse ends.
Further, there occurs another disadvantage, which is sometimes referred to as "cob-webbing" and wherein a yarn wound on the shoulders is slipped down from the shoulders.
In addition, in the conventionally known apparatus, since a so called "free length", i.e., a distance from the yarn guide to the contact roller, becomes long, there occurs the result that excessively high shoulders occur.
Besides, in the conventional apparatus, when a yarn is wound at a high speed higher than 5,000 m/min, the yarn is fluctuated due to the moment of inertia when the traverse motion is reversed, and the above-described disadvantages are even further pronounced.
Furthermore, in the conventional apparatus, since a common guide rail is disposed corresponding to rotary blades which are rotating in opposite directions and since the rotary blades rotating in opposite directions are arranged adjacent to each other, the traverse speed cannot be set freely. As a result, the following problems are inherent to the apparatus.
When the yarn is moved from the center of the traverse stroke toward the end of the traverse stroke, the yarn is moved behind the movement of the rotary blade by a distance equal to a distance from the position of the rotary blade to the point where the yarn reaches the contact roller multiplied by tan .theta., wherein .theta. is a winding angle. Further, when the traverse motion of the yarn is reversed at the end of the traverse stroke, the winding angle .theta. is also reversed, and the movement of the yarn in a traversing direction is temporarily stopped while the traverse motion is reversed. Thus, high shoulders are generated at the ends of the obtained package. Accordingly, the yarn quality may be deteriorated because of the high shoulders, and cob-webbing may occur due to loosening of the yarn.


A rotor, which includes a rotor main body and a fan. The rotor main body includes a rotor core, a rotary shaft extending through the rotor core, and a permanent magnet mounted in the rotor core. The fan includes a plurality of fixing portions embedded in the rotor main body and configured to fix the permanent magnet. The rotor has a simple structure, can be easily assembled, and has a low cost.

A rotor is used to cooperate with a stator, and rotate relative to the stator under the action of electromagnetic force, thereby driving a load connected to the rotor to rotate. A direct current motor, of which a rotor generally includes a rotary shaft, a rotor core, and a permanent magnet embedded in the rotor core. In order to cool the motor, a fan is generally mounted on an end of the rotor, and is driven by the rotor to rotate to cool the motor.
However, an assemble process of the motor with fan is complex.

Rotor, manufacturing method of the rotor, and motor


A telepresence robot includes a mobile platform, a camera, and a computer in communication with the platform and the camera. The computer receives video information from a remotely located camera relating to a gesture made by a remote human operator, and the robot is configured to operate based on the gesture. The computer may further predict an emotional state of a person interacting with the robot, based on video information received from the robot camera. A telepresence robot system includes: a telepresence robot having a mobile platform, a robot camera, a robot display, and a robot computer; and a control station, located remote to the robot, having a control station camera, a control station display, and a control station computer.

Known telepresence robots generally suffer a variety of issues. They are often very expensive, heavy and difficult to ship, require remote setup often involving skilled information technology assistance, incorporate proprietary hardware and/or software, provide low quality video and voice communications, and require frequent maintenance by skilled technicians.
While there has been a substantial amount of research in the field, mobile telepresence remains very expensive. Moreover, each device and even component devices that make up the telepresence robot are often unique and specific to a particular use, and that has substantially limited their use.
Traditionally, telepresence robots have been controlled using a joystick, a mouse or some similar input device. However, such input requires a human operator to communicating the robot in ways similar to how humans naturally interact with other humans, e.g. using body language, gestures and recognizing emotions.
Furthermore, telepresence robots and systems are typically limited to sensing in two dimensions only, and control of telepresence robots is typically limited to two dimensional controls.
Currently there is no central repository for gesture-based communication that crosses all platforms. Even for a single device, such as the Microsoft Kinect, there are very few common gestures; each interface design defines its own unique set.

Gesture enabled telepresence robot and system


A microcomputer for checking a flag in a flag circuit to determine whether or not to decrement a count of a program counter. If the flag indicates execution of a STOP instruction, the program counter value is decremented so that the address of a destination to return to at the end of debug interrupt handling is replaced by the address of the STOP instruction. If the flag gives any other indication, the program counter value is used unchanged as the return destination address that will be in effect at the end of debug interrupt handling.

1. Field of the Invention
The present invention relates to a microcomputer using a basic clock stop instruction (called the STP instruction hereunder) to execute debug-dedicated interruption (called debug interruption hereunder) whereby a program under development (called the user program hereunder) is debugged.
2. Description of the Prior Art
Heretofore, microcomputers for which a user program was being developed were provided with an interrupt circuit including a debug interrupt request generating circuit for debugging the program in question. Debug interrupt requests were issued illustratively by an externally furnished program debugger (called the external debugger hereunder) to interrupt user program execution for debug interrupt handling.
FIG. 1 is a block diagram showing how a conventional microcomputer is connected to an external debugger. In FIG. 1, reference numeral 1 stands for a microcomputer and 2 for an external debugger. Inside the microcomputer 1, reference numeral 10 is a central processing unit (CPU); 11 is an address bus; 12 is a data bus; 13 is a control signal line; 14 is a random access memory (RAM); 15 is a program memory; 16 is an interrupt control circuit; 17 is a debug support circuit; 18 is an interrupt request signal line over which a interrupt request signal is transmitted; and 19 is a debug bus.
FIG. 2 is a block diagram depicting an internal structure of the debug support circuit 17 inside the microcomputer 1. In FIG. 2, reference numeral 20 represents a trace circuit that outputs onto the debug bus 19 the run state of the CPU 10, i.e., the status of the address bus 11, data bus 12 and control signal line 13. Reference numeral 21 denotes a register to and from which data may be written and read by the external debugger 2 and by the CPU 10 of the microcomputer 1.
The microcomputer 1 of the above constitution works as follows:
Suppose that the microcomputer 1 is executing a user program stored in the program memory 15. In that case, the external debugger 2 reads trace data from the debug support circuit 17 of the microcomputer 1 over the debug bus 19, whereby the workings of the CPU 10 in the microcomputer 1 are monitored. When the effective address of the trace data in the CPU 10 has illustratively reached a predetermined address value, the external debugger 2 outputs an interrupt request signal onto the interrupt request signal line 18. Upon receipt of the interrupt request signal, the microcomputer 1 halts temporarily the current user program execution to carry out debug interrupt handling. With debug interrupt handling initiated, the CPU 10 performs a debug handling program held in the program memory 15 and communicates with the external debugger 2 via the register 21 of the debug support circuit 17.
Illustratively, after issuing the debug interrupt request, the external debugger 2 communicates with the CPU 10 through the register 21 of the debug support circuit 17 to know the register contents in the microcomputer 1 as well as the contents of the RAM 14. Debug interrupt requests are handled in the same manner as ordinary interrupt requests. That is, on accepting an interrupt request, the CPU 10 saves the program counter value (i.e, program counter contents) indicating what should be executed next into a memory area pointed to by a stack pointer (the area is generally allocated in the RAM 14). Then interrupt handling is carried out. At the end of the handling, an interrupt return instruction (called the RTI instruction hereunder) is executed whereby the program counter value in effect at the start of the interruption is read from the memory area designated by the stack pointer for transfer to the program counter. In the manner described, the user program is first interrupted by a debug interrupt request, the request is then handled appropriately, and the temporarily halted user program execution is resumed from the instruction next to the interrupted program instruction.
Debug interruption initiated by an interrupt request signal sent from the external debugger 2 over the interrupt request signal line 18 halts user program execution temporarily for debug handling. Generally, arrangements are made so that the debug interrupt handling time per request is sufficiently short so as not to hinder user program execution. For example, where memory contents in the microcomputer 1 are to be retrieved by the external debugger 2, the address range of the memory is divided into a plurality of portions so that each pass of debug interrupt handling will involve retrieving memory contents of only several addresses and will be finished over a sufficiently short period of time.
It should be noted that even where the STP instruction is executed to stop the basic clock inside the microcomputer 1, a debug interrupt request when issued cancels the STP instruction in order to perform debug interrupt handling. This means that upon return to the user program following execution of the RTI instruction, processing is resumed from the instruction next to the STP instruction in accordance with the program counter value which was saved upon interrupt initiation and which is retrieved from the memory area pointed to by the stack pointer.
The above-mentioned conventional techniques related to microcomputers are described illustratively by JP-A Nos. Sho 58-205226, Hei 5-73349, Sho 62-95644, and Hei 1-250143.
As described, conventional microcomputers suffer from the problem of the STP instruction getting canceled by an unintended event, i.e, by debug interrupt handling while a program is being debugged. For the external debugger 2 to circumvent the above problem requires performing three steps:
(1) Disassemble the program execution address portion in effect when a debug interrupt request is accepted, and search for an STP instruction. PA0 (2) Match analyzed trace data with the outcome of the disassembly to verify whether any STP instruction has been carried out. PA0 (3) If the STP instruction is judged to have been executed, decrement the program counter value saved into the memory area pointed to by the stack pointer at the time of debug interrupt initiation, thereby obtaining the address at which to execute the STP instruction upon completion of the current debug interruption.
Carrying out the additional steps above prolongs the time required to perform debug interrupt handling per request.


An expandable packer or anchor is disclosed. It features a gripping device integral to or mounted in a sleeve over the mandrel. Upon expansion, a sealing element engages an outer tubular and the gripping device, such as wickers on slips, preferably digs into the outer tubular. The expansion is preferably by pressure and can incorporate pressure intensifiers delivered by slick line or wire line. Release is accomplished by a release tool, which is delivered on slick line or wire line. It stretches the anchor or packer longitudinally, getting it to retract radially, for release. The release tool can be combined with packers or anchors that have a thin walled feature in the mandrel, to release by pulling the mandrel apart.

Traditional packers comprised of a sealing element having anti-extrusion rings on both upper and lower ends and a series of slips above or/and below the sealing element. Typically a setting tool would be run with the packer to set it. The setting could be accomplished hydraulically due to relative movement created by the setting tool when subjected to applied pressure. This relative movement would cause the slips to ride up cones and extend into the surrounding tubular. At the same time, the sealing element would be compressed into sealing contact with the surrounding tubular. The set could be held by a body lock ring, which would prevent reversal of the relative movement, which caused the packer to set in the first instance.
As an alternative to pressure through the tubing to the setting tool to cause the packer to set, another alternative was to run the packer in on wire line with a known electrically operated setting tool such as an E-4 made by Baker Oil Tools. In this application, a signal fires the E-4 causing the requisite relative movement for setting the packer. Some of these designs were retrievable. A retrieving tool could be run into the set packer and release the grip of the lock ring so as to allow a stretching out of the slips back down their respective cone and for the sealing element to expand longitudinally while contracting radially so that the packer could be removed from the well.
In the past, sealing has been suggested between an inner and an outer tubular with a seal material in between. That technique, illustrated in U.S. Pat. No. 6,098,717, required the outer tubular or casing to be expanded elastically and the inner tubular to be expanded plastically. The sealing force arose from the elastic recovery of the casing being greater than the elastic recovery of the inner tubular, thus putting a net compressive force on the inner tubular and the seal. Other expansion techniques, described in U.S. Pat. Nos. 5,348,095; 5,366,012; and 5,667,011 simply related to expansion of slotted tubulars, serving as a liner in open hole, as a completion technique. U.S. Pat. No. 4,069,573 illustrates the use of expansion to form a tubular casing patch.
The present invention relates to packers that can be expanded into sealing position. The surrounding tubular does not need to be expanded to set the packer of the present invention. Rather, an anchor such as slips is used to support the expanded sealing element and hold it in a set position. Preferably, existing setting tools, with minor modifications can be used to expand the packer of the present invention. Similarly releasing tools can be employed to remove the packer from its set position. The running string can be exposed to lower pressures than the packer through the use of pressure intensifiers. The expansion force can be pinpointed to the area of the packer, thus avoiding subjecting the formation or the running string to undue pressures during setting of the packer. Alternatively, the inner tubular may simply be an anchor for another tool or a liner string. The anchoring can be ridges on the exterior of the inner tubing directly or on a ring mounted over the inner tubular being expanded. The ring can be slotted to reduce the required expansion force.
The setting tool can be delivered through tubing on slick line or wire line or run into the well on rigid or coiled tubing or wire line, among other techniques. The release tool can be likewise delivered and when actuated, stretches the packer or anchor out so that it can be removed from the wellbore. Conventional packers, that have their set held by lock rings, can be released with the present invention, by literally pushing the body apart as opposed to cutting it downhole as illustrated in U.S. Pat. No. 5,720,343.
These and other advantages of the present invention will be more readily understood from a review of the description of the preferred embodiment, which appears below.

Expandable packer with anchoring feature


An endpoint system including one or more computing devices presents an object in a virtual environment (e.g., a shared virtual environment); receives gaze input corresponding to a gaze of a user of the endpoint system; calculates a gaze vector based on the gaze input; receives motion input corresponding to an action of the user; determines a path adjustment (e.g., by changing motion parameters such as trajectory and velocity) for the object based at least in part on the gaze vector and the motion input; and simulates motion of the object within the virtual environment based at least in part on the path adjustment. The object may be presented as being thrown by an avatar, with a flight path based on the path adjustment. The gaze vector may be based on head orientation information, eye tracking information, or some combination of these or other gaze information.

Virtual environments such as virtual reality environments, augmented reality environments, and the like, are growing in popularity. However, the ability of virtual environments to accurately model many real-world experiences remains limited by existing technology. Consider a scenario in which a user is engaged in a virtual activity, such as throwing an object at a target. Throwing objects with the human hand is a complex process: the release velocity of objects is a function of arm torque, hand grip, wrist flick, fingertip friction, and many more variables. Typical hand-tracking controllers are extremely simplistic relative to the human hand, and are incapable of reporting many of the throw properties outlined above. In fact, the only information provided by a typical VR controller is position and orientation, linear and angular velocity of the controller's center of mass, and the state of various buttons (if present), such as whether a trigger is depressed or not.
In the illustrative scenario, the hand/arm properties provided by typical controllers are sufficient to build object throwing interactions in virtual environments, but their lack of many hand properties described above means that users are unable to throw virtual objects with the same accuracy and precision as real world objects without unique training. Furthermore, such training may be a barrier to providing an immersive user experience in some contexts, such as entertainment and gaming, in which users expect to immediately participate in an activity without significant practice or training.

Systems and methods for assisting virtual gestures based on viewing frustum


A brush is provided for cleaning endoscope channels which comprises a tubular cannula having a first end and a second end. A wire insert is fitted within the cannula. A first brush having bristles supported on a first core is secured within the first end and a second brush having bristles supported on a second core is secured within the second end. The first core is spaced apart from the wire insert by a distance so as to leave a length of unsupported cannula. A flexible tubular tip is also secured on the first core with a substantial length of the tip free of the core. A depth limit stop having a stop surface thereon is fixed on the cannula spaced from the end of the second core by a distance which prevents the end of the second core from contacting endoscope channels.

The cross-sections of endoscopes are kept as small as possible because of the constraints of their uses. Very narrow structures often carry several tubular channels which must be cleaned and sterilized after each use. Their valves are manufactured to very close tolerances and are themselves made as small as possible. As a consequence, the cleaning of these expensive instruments is a painstaking procedure.
Conventional brushes for cleaning endoscopes have inherent shortcomings which make their use and the cleaning task unduly troublesome. Many brushes have a tendency to fold back upon themselves rather than to turn into a side channel or a port to clean it. Others expose the instrument to the risk of scratching by the metal core of their bristle brush.
It is an object of this invention to provide a cleaning brush with sufficient columnar strength that it can be pushed into a long channel but is still flexible enough at one of its ends to make the necessary turns, and with guidance means which assures that the turn will be made.
It is another object of this invention to provide at the other end of the cleaning brush a metal-cored bristle brush and a depth-limiting stop, which will prevent the metal core form reaching and scarring inside surfaces of the endoscope.


A protective relay utilizes a mechanism that averages a buffer of anticipated optimal closing times to provide for a more accurate method of determining when to permit the issuance of a breaker close signal. This is used in a Breaker Close Time (BCT) feature of performing synchronism checking in the electrical power industry (for example, in a generator protection device).

The present invention relates generally to the field of protective relaying, and more particularly to a xe2x80x9csynch checkxe2x80x9d algorithm for determining when to close a circuit breaker.
When both sides of an open circuit breaker are energized, caution must be taken so that, when the breaker closes, the two power systems can be tied together in a safe manner. This tying of power systems is called synchronization.
The synchronous check protective function measures the voltage magnitude, voltage phase angle, and power system frequency differences across an open circuit breaker. When all three of these parameters are within an acceptable level, the close command is issued, or permitted to be issued, in an attempt to close the circuit breaker. Circuit breakers do not close instantaneously. A typical breaker closing time is between 2 to 10 cycles (or 8-40 xc2xc-cycles). A goal of the present invention is to provide an improved algorithm for determining the optimal time to permit the breaker to close.
This invention utilizes a mechanism that averages a buffer of anticipated optimal closing times to provide for a more accurate method of determining when to issue a breaker close signal. This is used in a Breaker Close Time feature of performing synchronism checking in the electrical power industry (for example, in a generator protection device). Other features of the invention are described below.

Method for synchronizing two power systems using anticipation technique to compensate for breaker closing time