Abstract: An exemplary optical plate includes a first transparent layer, a second transparent layer and a light diffusion layer between the first and second transparent layers. The above-described three layers are integrally formed, with the first transparent layer in immediate contact with the light diffusion layer, and the second transparent layer in immediate contact with the light diffusion layer. The first transparent layer defines micro depressions protruding from an outer surface thereof. Each micro depression has at least three side surfaces connected to each other, and a transverse width of each side surface increases along a direction away from the light diffusion layer. The second transparent layer defines conical frustum depressions at an outer surface thereof.

Abstract: An exemplary optical plate includes a first transparent layer, a second transparent layer and a light diffusion layer. The light diffusion layer is between the first and second transparent layers. The light diffusion layer, the first transparent layer, and the second transparent layer are integrally formed. The light diffusion layer includes a transparent matrix resin, and diffusion particles dispersed in the transparent matrix resin. The first transparent layer defines first spherical depressions at an outer surface thereof that is farthest from the second transparent layer. The second transparent layer defines second spherical depressions at an outer surface thereof that is farthest from the first transparent layer. A backlight module using the optical plate is also provided.

Abstract: An antiglare light diffusing member is disclosed comprising a transparent base material; and an antiglare light diffusing layer including a binder matrix and a particle; wherein, as for the layer, arithmetic average roughness Ra1 (?c: 0.008 mm) on the basis of JIS-B0601-1994 is less than 0.008 ?m, Ra2 (?c: 0.8 mm) on the basis of JIS-B0601-1994 is 0.1-0.5 ?m and an internal haze is 1-7%.

Abstract: A solar concentrator may include a substantially planar surface, a curved primary mirror having a first perimeter, at least a portion of the first perimeter being in contact with the substantially planar surface, a secondary mirror disposed between the substantially planar surface and the curved primary mirror, the secondary mirror associated with a desired focal area, and a shield element disposed between the substantially planar surface and the curved primary mirror. The shield element is to prevent a portion of light reflected by the secondary mirror from reaching the primary mirror. In some aspects, a portion of the shield element may be disposed between the substantially planar surface and a plane which is substantially parallel to the substantially planar surface and which includes a portion of the desired focal area. The shield element may include a reflective surface to reflect light received from the secondary mirror toward the desired focal area.

Abstract: A film comprises: a transparent support; and an anti-glare layer having a haze value due to internal scattering of from 0 to 40% and a haze value due to surface scattering of from 0.3 to 20%.

Abstract: A pattern mask for forming a microlens includes mask pattern parts alternately arranged and corresponding to pixel regions in a matrix, wherein neighboring corners of the mask pattern parts overlap with each other.

Abstract: An apparatus, system and method are provided to inject an image into a viewing optical system, which is used for viewing a scene. An image injector includes first and second optical elements with first and second sides, respectively, and a reflective material. The first side adjoins the second side and the reflective material is between the adjoining sides. An image generator is optically coupled to the second optical element and generates an image. The image injector is placed at the aperture of the viewing optical system and passes energy from the scene into the viewing optical system. The reflective material reflects energy from the image generator into the viewing optical system. The image generator may produce the image based upon an information signal from an information generator. The reflective material may reflect energy from the scene into an output optical system and the information generator produce the information signal based on the energy received in the output optical system.

Abstract: Disclosed is a lighting optical system, including: a lighting optical system, comprising, a light separating means for separating incident light into three colored lights according to wavelength bands, and progressing the three separate colored lights for the same amount of distance from a light source of the incident light through different optical paths, and emitting the three separate colored lights to a first, a second and a third LCD, a first, a second and a third LCD for respectively receiving the three colored lights from the light separating means, and forming images therefrom; and a light combining means for synthesizing the three colored lights emitted from the first, second and third LCD, and outputting the synthesized light outside.

Abstract: A pyramidal microlens for observing hole wall structure and a camera lens structure using the microlens constructed by a cone and a hemisphere formed at the root of the cone, the tip part of which is placed into the observed hole wall, such that a user's naked eye may approach the hemispherical surface to observe a locally enlarging image of the inner surface of the hole wall, in addition, the lens being able to be placed longitudinally in a hollow lens tube, which may be placed on a surface, such that the lens may be used at any surface.

Abstract: A high-performance lens system including lens elements of small diameters for projecting on to a screen or the like in an enlarged fashion images from light valves such as mainly DMDs (Digital Micromirror Devices) for forming images by changing reflecting directions of light is provided. A lens system includes, sequentially in that order from a magnifying side, a first lens group which makes up a substantially afocal optical system as a whole and a second lens group having a positive refractive power as a whole, and depending upon applications, a third lens group made up of a single positive lens element is provided in the vicinity of a light valve such as a DMD on a contracting side of the second lens group.

Abstract: A high-performance lens system including lens elements of small diameters for projecting on to a screen or the like in an enlarged fashion images from light valves such as mainly DMDs (Digital Micromirror Devices) for forming images by changing reflecting directions of light is provided. A lens system includes, sequentially in that order from a magnifying side, a first lens group which makes up a substantially afocal optical system as a whole and a second lens group having a positive refractive power as a whole, the second lens group being configured to include, sequentially in that order from a magnifying side thereof, a first sub-lens group or 2a lens group having a negative refractive power as a whole and a second sub-lens group or 2b lens group having a positive refractive power as a whole, and depending upon applications, a third lens group made up of a single positive lens element is provided in the vicinity of a light valve such as a DMD on a contracting side of the second lens group.

Abstract: The electrowetting cel (15) that is primarily to be used as a variable focus lens, comprises a liquid chamber (50) containing a first and a second immiscible fluid (51, 52), which are in contact across a meniscus (14) and of which the first fluid (51) is a polar and the second (52) is electrically conductive. The liquid chamber (50) is provided with an inner face (18), at which a fluid contact layer (10) is present, which has an inherent attraction to the first liquid. An electrode is separated from the liquid chamber (50) through this fluid contact layer (10). The fluid chamber (50) is constructed such that it has a small diameter at an operating point (101) at the inner face (18) than at a point of tangency (102), while a tangent (R1) to the operating point (101) encloses a smaller angle with the optical axis (OA) of the cell (15) than a tangent (R2) to the second point (102).

Abstract: A piezoelectric-driven optical lens module is disclosed, including a lens body, a piezoelectric actuator for providing a driving force, and a position sensor for detecting position variations. The lens body includes at least a hollow base body, a lens barrel exhibiting axial and rotational freedom of movement positioned inside the hollow base body, and a lens set disposed inside the lens barrel. The lens barrel is driven by a piezoelectric actuator to move the lens set along the optical axis to achieve the optical functions of zooming and focusing. The position sensor is configured to detect the axial position of the lens barrel with respect to the hollow base body, thereby providing a simple structure to improve on the drawbacks of prior techniques.

Abstract: Provided is a lens apparatus mounted to a camera including an image-pickup element, including: a focus lens means movable in an optical axis direction for focusing; a zoom lens unit; a zoom detector for detecting a zoom value of the zoom lens unit; an aperture-stop device; a stop-value detector; a splitting optical unit; a focus-condition detection unit; an actuator; a controller for controlling the actuator based on an output from the focus-condition detection unit; and a manual operation member, wherein the controller obtains an F-number of the lens apparatus based on outputs from the zoom detector and stop-value detector and when the F-number exceeds a predetermined value, the controller causes the actuator to stop the focus lens unit and switches to a condition in which the focus lens unit is driven by the manual operation member.

Abstract: A first lens group having a negative refractive power, an aperture diaphragm, and a second lens group having a positive refractive power are arranged in order from an enlargement side. A reduction side of a projection lens is made essentially telecentric. Further, cemented triplet lenses, each of which includes cemented three lenses, are provided in the first lens group and the second lens group, respectively. Further, air spacing which enables placement of a mirror is ensured between the first lens group and the second lens group. Moreover, specific conditional expressions for the lens are satisfied.

Abstract: A system and method for uniformity correction having light leak and shadow compensation is provided. The system includes multiple correction elements and an optical compensation plate. Adjacent correction elements are separated by a gap. The optical compensation plate includes a pattern having multiple gap compensation segments. The pattern has an attenuation which is different than the attenuation of the remaining portions of the optical compensation plate. The location of each compensation segment on the compensation plate corresponds to the location of the corresponding gap between adjacent correction elements in the illumination slot. The width of each compensation segment is dependent upon the angle of the light incident on the correction system. The pattern can be located on the top surface or on the bottom surface of the compensation plate. In addition, the compensation plate can be located above or below the plurality of correction elements.

Abstract: A zoom lens having a plurality of lens groups which performs zooming by changing distances between groups includes a reflective member to bend an optical axis which passes through the plurality of the lens groups. The plurality of lens groups includes, in order from an object side to an image plane side: a first lens group having a positive refractive power and fixed in position; a second lens group having a negative refractive power and to be moved along the optical axis direction when zooming; a third lens group having a positive refractive power and fixed in position; a fourth lens group having a positive refractive power and to be moved in the optical axis direction to compensate a position change of the image plane when zooming and focusing; and a fifth lens group having a negative refractive power and fixed in position when zooming.

Abstract: An imaging lens includes: in order from an object side, an aperture diaphragm; a first lens of a positive lens having a convex surface on the object side; a second lens of a meniscus lens having a concave surface on the object side; and a third lens. The imaging lens satisfies: f/f3<0.95 and BR2<0. BR2 satisfies BR2=A/D4, A represents a distance from a vertex position on a object-side surface of the second lens and on an optical axis to a position on a image-side surface of the second lens through which a light ray passes toward a corner of an image height, provided that a traveling direction of the light ray is taken as appositive direction, and D4 represents a center thickness of the second lens. f represents a focal length of the imaging lens. f3 represents a focal length of the third lens.

Abstract: A light refracting device includes: a mounting seat adapted for mounting at least one LED thereon; and at least one transparent cap mounted on the mounting seat and adapted to be capped on the LED. The cap defines an inner space and has a dome-shaped end portion that has a curved inner surface formed with a plurality of refracting protrusions protruding into the inner space for refracting light therethrough into the environment, and a plurality of recesses disposed alternately with the protrusions.

Abstract: An improved device for reflecting, radiating, or receiving electromagnetic radiation, acoustic waves, or other energy forms through the use of a membrane stretched across a lightweight, round, frame structure. A near perfectly round and flat semi-rigid backplane surface (1) and a near perfectly round ring or stack of rings (2) are mutually reinforced, forming a raised circumferential planar surface, and a cavity within. A membrane (3) is attached to the top of the rings, forming one wall of a sealed chamber. A source of sub-ambient pressure (4) is applied to the chamber, causing a primary uniform deformation in the membrane for the purpose of manipulating electromagnetic radiation, acoustic waves, or other energy. The backplane surface also deforms uniformly, increasing the strength of the structure. A flat, rigid floating batten (5) prevents waves or wrinkles from forming in the membrane material.

Abstract: Disclosed are an external light shielding film with a substrate including a transparent resin, an external light shielding pattern formed on a surface of the substrate and having a plurality of external light shielding parts including a light absorbing material, a method of manufacturing the external light shielding film, and a filter for a display having the external light shielding film. The light absorbing material consists of a base resin and a light absorbing substance, and at least one of a concentration of the light absorbing substance and a refractive index of the base resin varies in a stepwise manner.

Abstract: In a magnetic tape device, upon receiving a magnetic tape cartridge from an insertion slot, an authentication unit reads data that is stored in an electronic tag and based on the read data, checks validity of the magnetic tape cartridge. A robot conveys only a valid magnetic tape cartridge to a drive.

Abstract: A magnetic writer includes a write element and an oscillation device disposed adjacent to the write element. The first oscillation device includes a first magnetic layer, a second magnetic layer having a magnetization vector including a component perpendicular to a major plane of the first magnetic layer. The first nonmagnetic layer disposed between the first magnetic layer and the second magnetic layer. The first oscillation device generates a high-frequency oscillation field when a current is directed perpendicular to the major plane of the first magnetic layer.

Abstract: An apparatus, system, and method are disclosed for fly height detection. The apparatus includes an actuator configured to induce vibrations in a glide head that is configured to detect physical asperities on a disk surface. The apparatus may also include a second end of the suspension arm coupled with the glide head and a sensor module that is configured to communicate with a control module in response to the glide head coming in contact with at least one physical asperity. The system includes the apparatus, a disk having a surface comprising physical asperities, and a head gimbal assembly configured to calibrate a fly height margin for the disk. The method includes inducing vibrations in a glide head, detecting physical asperities on a disk surface, and communicating with a control module in response to the glide head coming in contact with at least one physical asperity.

Abstract: According to one embodiment, in a disk drive having the function of performing a self-servo writing, the CPU is configured to calculate correction values for only those of servo tracks which have been designated and to store the correction values in servo sectors, when a process of calculating STW-RRO correcting values during a self-run test.

Abstract: Embodiments of the present invention relate to retracting a magnetic head of a disk drive device to a retract position in accordance with a fall state, and to suppressing the performance degradation due to erroneous fall determinations as well as occurrence of damage by a head-disk crash. According to one embodiment of the present invention, in a Hard Disk Drive (HDD), a servo controller moves a head slider to a cylinder at the side of a ramp at a predetermined timing that a fall determiner determines that it is falling and an unload controller starts an unload process. This shortens the time between determination by the fall determiner that it is falling to retraction of the head slider to the retract position. Furthermore, it prevents increase of the erroneous determinations by relaxing the fall determination condition for safety. Also, it shortens the time that the head slider returns to the initial position before the seek in case that it is not determined that it is falling.

Abstract: A magnetic disc drive includes a head that is configured to record information in a recording medium or reproduce the information from the recording medium, a housing that houses the recording medium and the head, and a vibration damping mechanism that reduces a vibration of the housing, and includes a weight attached to the housing and a deformation reducer that reduces a deformation of the housing caused by the weight.

Abstract: A hydrodynamic bearing device which can enhance operating efficiency of a step of filling a lubricant and also effectively suppress leakage of the lubricant to an outer peripheral portion of the hydrodynamic bearing device; a spindle motor including the same; and an information recording and reproducing apparatus are provided A hydrodynamic bearing device includes a sleeve, a shaft, a lubricant, a plurality of lube repellent application areas, and a lube repellent non-application area. The sleeve has an insertion hole as a bearing hole on at least one end. The shaft is inserted into the insertion hole of the sleeve and is supported so as to be relatively rotatable with respect to the sleeve. The lubricant is interposed in a clearance between the sleeve and the shaft. The plurality of lube repellent application areas are formed into a circular pattern with the shaft being a substantial center on at positions outside the insertion hole of an open upper surface of the sleeve in a radial direction of the shaft.

Abstract: An EMI protective magnetic read head for use in a magnetic rule position feedback system to read signal from a magnetic rule is disclosed to include a sensor for reading signal from a magnetic rule, and an outer shell that houses the sensor and is made out of a magnetic conductive material, for example, pure ferrite or silicon steel that guides surrounding electromagnetic noises away from the sensor when the sensor is reading a magnetic rule.

Abstract: Provided are a magnetic recording medium and a method of fabricating the same. The magnetic recording medium includes a substrate; and a recording layer, wherein the recording layer is formed of a plurality of magnetic dots, and a non-magnetic region that is formed on the substrate to isolate each of the magnetic dot.

Abstract: A slide apparatus that provides horizontal support to a disc drive blade is described. The slide apparatus essentially includes a slider beam, a guide rail, a chassis and a retaining member. The slider beam possesses a slotted feature that extends at least partially along the length of the slider beam. The guide rail, which is adapted to be attached to a frame, constrains the slider beam to move only along the length of the guide rail. A retaining member is anchored to the chassis and extends into said slotted feature. The chassis, which supports the disc drive blade, is confined by the retaining member to move essentially only along the slotted feature in the slider beam.

Abstract: A head support mechanism includes a suspension for supporting a magnetic head slider with a thin-film magnetic head, having a slider mounting section on which the magnetic head slider is fixed, and a heating unit formed on the slider mounting section of the suspension. The heating unit is capable of producing heat.

Abstract: The head stack assembly of a hard disk drive includes a bobbin, and a printed circuit board attached to the bobbin. The bobbin forms an end of the head stack assembly that is rotatable about an axis of a shaft. The printed circuit board has a flat conductive pattern of a plurality of traces through which current is supplied. The conductive pattern constitutes the voice coil motor of the hard disk drive. The hard disk drive has magnets disposed above and below the bobbin, respectively, to generate a magnetic field across the conductive pattern and the poles of the magnets are arranged such that an electromotive force that rotates the HSA is produced when current flows through the conductive pattern. The flat conductive pattern allows the voice coil motor to be relatively thin and precisely manufactured. In addition, the magnets need to encompass only a small region and thus, a compact and lightweight hard disk drive can be realized.

Abstract: A tape head designed for transducing data on a magnetic recording tape that is subject to tape dimensional changes. The tape head includes two or more arrays of transducer elements having different transducer spacing distances corresponding to different track spacing distances to be transduced. One of the transducer arrays may be used for transducing the tape under nominal tape track spacing conditions. Another transducer array may be used for transducing the tape when the tape track spacing is reduced due to the tape shrinkage. Still another transducer array may be used for transducing the tape when the tape track spacing is enlarged due to tape expansion.

Abstract: A magnetic head of either CIP or CPP configuration is disclosed, having a read sensor with a strongly pinned ferromagnetic layer due to increased electronic exchange with the AFM layer. The read sensor includes a lower seed layer whose material is chosen from a group consisting of Ta, NiFeCr, NiFeCoCr, NiFe, Cu, Ta/NiFeCr, Ta/NiFeCr/NiFe, Ta/Ru and Ta/NiFeCoCr, and an upper seed layer where the upper seed layer material is chosen from a group consisting of Ru, Cu, NiFe, Cu(x)Au(1-x)(x=0.22-0.5) alloys, Ru(x)Cr(1-x)(x=0.1-0.5) alloys, NiFeCr and NiFeCoCr. An AFM layer is formed on the upper seed layer and a ferromagnetic pinned layer is formed on the AFM layer. The exchange coupling energy Jk between the AFM layer and pinned layers exceeds 1.3 erg/cm2. Also disclosed is a method of fabrication of a magnetic head including a read head sensor with a strongly pinned ferromagnetic layer due to increased electronic exchange.

Abstract: A magnetoresistive sensor having magnetically anisotropic bias layers for biasing the free layer of the sensor. The sensor includes a sensor stack with a pinned layer structure and a free layer structure and having first and second sides. Hard bias structures for biasing the magnetization of the free layer are formed at either side of the sensor stack, and each of the hard bias structure includes a hard magnetic layer that has a magnetic anisotropy to enhance the stability of the biasing. The hard bias layer is formed on a buffer layer and a seed layer, the seed layer being sandwiched between the buffer layer and the hard bias layer. The buffer layer has an anisotropic surface texture that promotes the magnetic anisotropy in the hard bias layer. The buffer layer can be CrMo or Ru or can be a bi-layer including a layer of CrMo with a layer of Ru over the CrMo. The seed layer can be constructed of a material having a BCC structure and is preferably constructed of CrMo.

Abstract: A switching system is provided. The switching system includes electromechanical switching circuitry, such as a micro-electromechanical system switching circuitry. The system may further include solid state switching circuitry coupled in a parallel circuit with the electromechanical switching circuitry, and a controller coupled to the electromechanical switching circuitry and the solid state switching circuitry. The controller may be configured to perform selective switching of a load current between the electromechanical switching circuitry and the solid state switching circuitry in response to a load current condition appropriate to an operational capability of a respective one of the switching circuitries.

Abstract: A motor power device includes a power circuit having a low voltage part that receives and converts AC power and outputs DC voltage, wherein a first power for a motor drive coil and a second power for a control circuit controlling the motor drive coil are supplied by using the DC voltage outputted from the power circuit, and a motor may include the motor power device. In one aspect, a motor power device is provided that may supply a DC voltage by using an AC power regardless of the magnitude of the AC power. In another aspect, a power circuit may output suitable DC voltage with less cost even though the magnitude of the AC power has changed. In yet another aspect, a motor power device is provided that may supply power for driving a motor drive coil and a power for a control circuit controlling the motor drive coil using one power circuit.

Abstract: A system and method is provided for monitoring the speed signals of a first fan and a second fan. The system includes a selection signal generation device, a logic gate, a counter and a control device. The selection signal generation device outputs a selection signal to the logic gate having two different states. Based upon the speed signals and the state of the selection signal, the logic gate outputs an output speed signal representing the speed signal of the first fan or second fan to the counter. The counter converts the output speed signal to a digital speed datum. The control device calculates the speed of the first fan or the second fan according to the selection signal and the digital speed datum. The changes of state of the selection signal permit the system to obtain the respective speeds of the two fans in different access cycles.

Abstract: An anti-surge power adapter comprising: a transformer; a pair of copper sheets which, with a certain gap between themselves, is connected between said transformer and the power input terminal or on the said transformer to release instantaneous surge. The present invention features low cost, simple process and high reliability, and only requires two copper sheets or a PCB or other insulating board with copper sheets to be connected in the circuitry. The anti-surge power adapter uses copper sheets to release instantaneous high voltage, features quick response and can withstand an instantaneous high voltage of 6-17 KV. This invention is applicable to linear or switching power adapter.

Abstract: A HomePlug apparatus is electrically connected to a power network and includes a HomePlug processing circuit and a surge protecting circuit. The HomePlug processing circuit is electrically connected to the surge protecting circuit. The surge protecting circuit has at least one inductor, at least one capacitor and at least one arrester. The inductor is electrically connected to the power network. The arrester is electrically connected to a ground. The inductor, the capacitor and the arrester are connected in series to guide a surge originated from the power network to the ground.

Abstract: An ESD protection circuit is provided for protecting an integrated circuit from ESD damage and for protecting lightening surge. The ESD protection circuit includes a first snapback device and a second snapback device. The first snapback device is connected to a first terminal having a negative voltage of the integrated circuit during the operation of the integrated circuit. The first snapback device includes an anode coupled to the first terminal of the integrated circuit. The cathode of the first snapback device is coupled to a VCC terminal of the integrated circuit. The second snapback device has a cathode coupled to the VCC terminal. The anode of the second snapback device is connected to the ground of the integrated circuit. The snapback devices operate as silicon-controlled rectifiers (SCR) to protect the integrated circuit.

Abstract: An electrostatic discharge (ESD) protection circuit. The ESD protection circuit comprises a silicon controlled rectifier (SCR) device and a metal-oxide-semiconductor (MOS) triggering device. The SCR device has a cathode connected to a first fixed potential and an anode. The MOS triggering device has a gate and a source connected to the first fixed potential and a drain connected to the anode. In addition, the MOS triggering device is not physically disposed in the SCR device.

Abstract: A semiconductor device is disclosed, which includes first, second and third power supply pads arranged in a peripheral area of a semiconductor chip, the second pad applied with a higher potential than the first pad, and the third pad applied with a higher potential than the second pad, first, second and third power supply wirings arranged in the peripheral area, the first wiring connected to the first pad, the second wiring connected to the second pad, and the third wiring connected to the third pad, a plurality of first electrostatic protection circuits arranged in the peripheral area and connected between the first and second wirings in correspondence to the first, second and third pads, and a plurality of second electrostatic protection circuits arranged in the peripheral area and connected between the second and third wirings in correspondence to the first, second and third pads.

Abstract: A PCM current differential relay is provided with a sampling synchronizing circuit unit which, on the basis of a deviation in sampling timing between digital current data of a local end and digital current data of a remote end inputted from the remote end, synchronizes the digital current data of the local end and the digital current data of the remote end. In accordance with the digital current data of the local end and the digital current data of the remote end synchronized by the sampling synchronizing circuit unit, relay operation of the PCM current differential relay is carried out by a relay operation unit of the PCM current differential relay.

Abstract: Within a group of components in a circuit, each component in the group has a thermal detector that describes whether that component is operating at a temperature that is normal, high or fatal. A first signal representing a first component's temperature is sent downstream to a second component in the group. If the second component is operating at the first component's temperature or lower, then the first signal is passed on downstream from the second component. However, if the second component is at a higher temperature, then the second component generates a second signal that represents the second component's temperature, and sends that second signal downstream. A signal representing the highest temperature detected in the group eventually reaches a master controller that, depending on the signal received from the group, lets the group continue to operate normally, throttles the group down, or else shuts the group down.

Abstract: There is provided a backlight unit that determines whether a lamp performs an abnormal operation by detecting a voltage that is induced in a power conversion transformer without using a complicated and expensive detection circuit. A backlight unit having a protection circuit using induced voltage detection according to an aspect of the invention includes an inverter part including a primary coil receiving power and at least one secondary coil converting the power from the primary coil to AC power set beforehand, a lamp part including at least one lamp receiving the AC power from the inverter part to emit light, a detection part including conductors detecting voltages electromagnetically induced in the secondary coil, and an abnormality determining part comparing detection voltages from the detection part with a reference voltage set beforehand.

Abstract: A transient blocking unit (TBU) includes at least two depletion mode transistors connected to each other such that they can rapidly switch from a normal low-impedance state to a high-impedance current blocking state in response to an over-voltage or over-current condition. This behavior makes TBUs useful for protecting electrical devices and circuit from harmful electrical transients. Some kinds of transistors can exhibit a phenomenon known as current collapse, where channel conductance is temporarily reduced after exposure to high voltage. Although current collapse is undesirable, transistors exhibiting current collapse can have otherwise favorable properties for TBU applications. According to the present invention, a TBU is provided where a diode is placed in parallel with a TBU transistor that can exhibit current collapse. The diode prevents high power dissipation in a current collapsed transistor, thereby reducing the vulnerability of the TBU to permanent damage or destruction in service.

Abstract: A protection circuit with a positive field effect transistor coupled to a power source, a negative field effect transistor connected to a pass-gate and a circuit ground, a circuit input terminal, a multi-level source of protection voltage coupled to an external circuit and at least three additional field effect transistors. A drain of the negative field effect transistor couples to a gate of the positive field effect transistor. When the circuit input terminal is low the pass-gate is on; when the circuit input terminal is high the pass-gate is off. Embodiments of the invention also include stacks of three or more field effect transistors.

Abstract: A repair circuitry consisting of at least one electrical fuse forming part of a conduction path between a positive voltage supply (VQ) pad and a complimentary lower voltage supply source (Vss). The repair circuitry includes at least one switching device and at least one control circuit. The at least one first switching device has a control terminal and is coupled between the Vss and the at least one electrical fuse. The at least one control circuit is coupled to the control terminal and the Vss respectively. Upon an application of a positive high voltage to the VQ pad, the at least one control circuit delays the turn-on state of the at least one first switching device for a predetermined period of time, thereby preventing the at least one electrical fuse from being mistakenly programmed.