Abstract: The present invention provides a multicolor display optical composition comprising a dispersion medium, a periodic structure having a porous structure inside communicated with the outside, and mobile particles contained in the dispersion medium so as to be movable and having a volume average primary particle diameter from 1 nm to 80 nm in a dispersion state in the dispersion medium, a volume average particle diameter of coagulated particles of 100 nm or larger in optical coagulation state by stimulation application, and having a refractive index different from that of the dispersion medium by 0.1 or more, wherein the mobile particles show no coloration in the dispersion state when the particles are dispersed in the dispersion medium and show white coloration with a predetermined whiteness value or higher in the coagulation state when the particles are coagulated, an optical device, and a display method of the optical device.

Abstract: A method of manufacturing an electrophoretic display sheet, comprising: forming a wall material on a first substrate, the wall material defining a disposing region; disposing a plurality of microcapsules to the disposing region, each of the plurality of microcapsules including an electrophoretic dispersion liquid in a shell; and arranging at least a part of the plurality of microcapsules on the disposing region by rubbing the wall material with a plate to sweep the plurality of microcapsules.

Abstract: A transmission apparatus designed to be capable of monitoring faults which occur between the input stage of an optical multiplexer and the input stage of an optical amplifier, appropriately switching between automatic gain control and automatic level control, and outputting signal lights with appropriate optical power, without using a spectrum analyzer. The optical multiplexer combines the wavelengths of a plurality of signal lights. The optical amplifier is connected at the latter stage of the optical multiplexer, and operates in the automatic gain control mode or in the automatic level control mode, the automatic gain control mode maintaining a constant gain for wavelength-multiplexed signal light, the automatic level control mode maintaining constant output power for the wavelength-multiplexed signal light.

Abstract: Method, apparatus and arrangement according an exemplary embodiment of the present invention can be provided for analyzing and/or illustrating at least one portion of an anatomical structure. For example, light can be forwarded to such portion so as to generate first information which is related to the portion. For example, the light can be provided on or within a subject. The first information can be received, and at least one section of the portion may be selected based on the first information so as to generate second information. A magnification of a display of the portion may be progressively modified as a function of the second information.

Abstract: An optical filter of a plasma display panel (PDP) and its fabrication method are disclosed. The optical filter includes an electromagnetic wave shield layer having a bias angle formed by cutting a mesh film along a predetermined direction.

Abstract: A microscope imaging apparatus and a biological-specimen examination system that can accurately carry out measurement even for an object under examination having substantial brightness non-uniformity are provided. The microscope imaging apparatus includes a stage that holds the object under examination, an illumination unit that illuminates the object under examination, an image-acquisition unit that acquires images of the object under examination, and a motion unit that moves the stage and the image-acquisition unit relative to each other. The image-acquisition unit includes an imaging device capable of image acquisition using a time delay integration method. When acquiring a plurality of images of the object under examination, the exposure time during which accumulated charge is produced in the imaging device is made different for each of the acquired images, and the plurality of images are combined into a single image.

Abstract: A microscope imaging apparatus and a biological-specimen examination system that can accurately carry out measurement even for an object under examination having substantial brightness non-uniformity are provided. The microscope imaging apparatus includes a stage that holds the object under examination, an illumination unit that illuminates the object under examination, an image-acquisition unit that acquires images of the object under examination, and a motion unit that moves the stage and the image-acquisition unit relative to each other. The image-acquisition unit includes an imaging device capable of image acquisition using a time delay integration method. When acquiring a plurality of images of the object under examination, the exposure time during which accumulated charge is produced in the imaging device is made different for each of the acquired images, and the plurality of images are combined into a single image.

Abstract: A microscope imaging apparatus and a biological-specimen examination system that can accurately carry out measurement even for an object under examination having substantial brightness non-uniformity are provided. The microscope imaging apparatus includes a stage that holds the object under examination, an illumination unit that illuminates the object under examination, an image-acquisition unit that acquires images of the object under examination, and a motion unit that moves the stage and the image-acquisition unit relative to each other. The image-acquisition unit includes an imaging device capable of image acquisition using a time delay integration method. When acquiring a plurality of images of the object under examination, the exposure time during which accumulated charge is produced in the imaging device is made different for each of the acquired images, and the plurality of images are combined into a single image.

Abstract: A stereomicroscope (1) is disclosed, having a main objective (2) which defines an optical viewing path and determines a beam base (16a) on an object (16) which is to be examined. In addition, at least one deflecting element is provided which deflects the optical viewing path coming from the main objective (2). At least one of the deflecting elements is provided with a deformable mirror surface, the deflecting element being connected to a control unit (32) for adjusting the deformable mirror surface.

Abstract: A stereoscopic microscope workstation providing high-resolution, real-time data to a display means. Various embodiments are disclosed including desktop and free-standing workstations. An image processing unit can be implemented, providing for natural orientation of the magnified image of the viewed object, also allowing rotation, cropping, filtering and other image manipulation features. Methods of performing a procedure utilizing the stereoscopic microscope workstation are disclosed, including a method of manipulating an object while viewing the object in a high-resolution real-time magnified image.

Abstract: A stereoscopic microscope workstation providing high-resolution, real-time video signals to a display means. A stereoscopic microscope workstation providing high-resolution, real-time data to a display means. Various embodiments are disclosed including desktop and free-standing workstations. An image processing unit can be implemented, providing for natural orientation of the magnified image of the viewed object, also allowing rotation, cropping, filtering and other image manipulation features. Methods of performing a procedure utilizing the stereoscopic microscope workstation are disclosed, including a method of performing a procedure of simultaneously utilizing both foveal vision and peripheral vision.

Abstract: The invention relates to a microscope having an optics system which represents an object on an image sensor and a screen that shows the image data provided by the image sensor and which is the only output medium for visually observing the object, wherein the representation capability of the optics system and the resolution (A) of the image sensor complies with the following correlation: F×N/M=0.5 A, wherein F indicates a factor, N indicates the numerical aperture of the optics systems, M is the magnification factor and A indicates the resolution of the image sensor in pixels per millimeter.

Abstract: Light in the visible spectrum is modulated using an array of modulation elements, and control circuitry connected to the array for controlling each of the modulation elements independently, each of the modulation elements having a surface which is caused to exhibit a predetermined impedance characteristic to particular frequencies of light. The amplitude of light delivered by each of the modulation elements is controlled independently by pulse code modulation. Each modulation element has a deformable portion held under tensile stress, and the control circuitry controls the deformation of the deformable portion. Each deformable element has a deformation mechanism and an optical portion, the deformation mechanism and the optical portion independently imparting to the element respectively a controlled deformation characteristic and a controlled modulation characteristic. The deformable modulation element may be a non-metal.

Abstract: A portable screen assembly includes a first side support and a second sides support, where the first side support and the second side support are connected to a fabric. The portable screen assembly also includes a center support brace connected to the fabric. A first support leg extends downward from the first side support and the a second support leg extends downward from the second side support. A motorized portable screen assembly includes a fabric, a first side support, a second side support, and a center support assembly. The fabric is connected to the first side support and the second side support. An expandable support brace is connected to the first side support, the second side support, and the center support assembly. An automatic deployment mechanism is connected to the expandable support brace, and the automatic deployment mechanism drives the expandable support brace to open in a horizontal direction.

Abstract: A lens sheet, transmission screen, and a rear projection display are provided. The lens sheet includes fly-eye lens elements periodically arranged on one side of a transparent base, wherein the lens elements are composed of a UV-curing type resin, and the storage elastic modulus at a reference temperature of 25° C. and a frequency of 1031 6 Hz, in a master curve obtained from measurement of dynamic viscoelasticity of the resin, ranges from 1×107 Pa to 1×109 Pa.

Abstract: A transmissive screen includes a first board member on a light source side, the first board member including a Fresnel lens on the surface of the light source side and one of a vertical lenticular lens or a horizontal lenticular lens on the surface of a viewer side; and a second board member on the viewer side, the second board member including the other of the vertical lenticular lens or the horizontal lenticular lens. The first board member includes a diffusing layer between the Fresnel lens and the lenticular lens on the surface of the viewer side at a position close to the Fresnel lens, wherein a relation represented by ??tan?1(fp/2L) is obtained, where ? is a diffusion angle at which a distribution characteristic of diffused light passing through the diffusing layer is half the peak gain, fp is a pitch of the Fresnel lens and L is a light path between the diffusing layer and the lenticular lens on the surface of the viewer side.

Abstract: A portable screen assembly includes a first side support assembly connected to a fabric, a second side support assembly connected to the fabric, and a center support assembly. The first side support assembly has a first engagement subassembly fastened to the first side support assembly and the second side support assembly has a second engagement subassembly fastened to the second side support assembly. The center support assembly has a first receiving subassembly to receive a first engagement tab of the first engagement subassembly and also has a second receiving subassembly to receive a first engagement tab of the second engagement subassembly. The first receiving subassembly, the second receiving subassembly, the first engagement subassembly, and the second engagement subassembly hold the first side support assembly and the second side support assembly to the center support assembly.

Abstract: A layered polarized diffractive filter capable of changing the wavelength of light to be transmitted or diffraction-shielded is provided. A polarized diffractive filter is capable of receiving light having at least two different peak wavelengths so as to shield light having at least one of the peak wavelengths by diffraction and to transmit light having the other peak wavelengths. The polarized diffractive filter comprises transparent substrates 11, 13 on which cyclic concave/convex portions 12 are formed as a diffractive grating and the concave/convex portions 12 are filled with a liquid crystal material as an optical member, thereby constituting a diffractive filter. The layered polarized diffractive filter comprises two polarized diffractive filters layered so that longitudinal directions of the diffractive grating of the polarized diffractive filters intersect orthogonally each other.

Abstract: An antiglare antireflective film is provided and includes: a transparent substrate; and at least one layer. The antiglare antireflective film having a surface having asperities in which: 15% to 70% of the total asperities are asperities, each having a tilt angle of 1° or below, which a line normal to each asperity profile form with a line normal to the transparent substrate; and at most 3% of the total asperities are asperities, each having the tilt angle of 10° or above.

Abstract: A semi-conductor based imager includes a microlens array having microlenses with modified focal characteristics. The microlenses are made of a microlens material, the melting properties of which are selectively modified to obtain different shapes after a reflow process. Selected microlenses, or portions of each microlens, are modified, by exposure to ultraviolet light, for example, to control the microlens shape produced by reflow melting. Controlling the microlens shape allows for modification of the focal characteristics of selected microlenses in the microlens array.

Abstract: A tunable micro-aspherical lens is disclosed, which employs two potential differences provided by two sets of electrodes to dynamically change the bottom area and the central height of the liquid polymer lens. The tunable micro-aspherical lens includes a tunable lens, a lower electrode plate, a hydrophobic pattern, an insulation layer and an upper transparent electrode plate. Also, a manufacturing method of a tunable micro-aspherical lens is disclosed, which includes forming a lower electrode plate, forming an insulation layer, determining a position of the tunable lens, controlling the bottom area and the central height of the tunable lens. The tunable micro-aspherical lens of the present invention eliminates spherical aberration and improves the focus spot resolution to shrink the focus spot and thus to provide better optical quality.

Abstract: A compact zoom lens includes, in order from an object side to an image side, a first lens group (1) of negative refractive power, and second, third, fourth and fifth lens groups (2, 3, 4, 5) of positive refractive power. The second, third and fourth lens groups are movable to effect zooming and focusing. During zooming from the telephoto end to the wide-angle end, the fourth lens group moves from the object side to the image side. The compact zoom lens has a long back focal length with various aberrations satisfactorily corrected, and a small F-number for enhanced image brightness.

Abstract: At least one exemplary embodiment is directed to a zoom lens system which includes a first lens unit having negative refractive power and a second lens unit having positive refractive power. The first and second lens units are provided in order from the object to image sides. The distance between the first and second lens units change during zooming. The first lens unit includes a compound optical element including a lens element and a resin layer having optical performance different from that of the lens element and being stacked on the lens element. The zoom lens system can satisfy: 20<|?dg??dj| and fg/fj<0, where fg and ?dg represent the focal length and the Abbe number of the lens element and fj and ?dj represent the focal length and the Abbe number of the resin layer.

Abstract: At least one exemplary embodiment is directed to a zoom lens includes first, second, and third lens units having negative, positive, and positive refractive powers, respectively, in order from an object side to an image side and performs zooming by moving each lens unit. The first lens unit includes a negative lens whose surface on the image side has a concave shape and a positive lens whose surface on the object side has a convex shape in order from the object side to the image side. At least one surface of the negative lens has an aspheric shape.

Abstract: A zoom lens system comprising, in order from an object side, a first lens unit having a negative refractive power, a second lens unit having a positive refractive power and a third lens unit having a positive refractive power, wherein during zooming from a wide-angle end to a telephoto end, a space between the first lens unit and the second lens unit narrows, at least the second unit move only toward the object side, and the third lens unit G3 is constituted of one positive lens.

Abstract: A variable magnification optical system for forming an optical image of an object onto a light acceptance surface of an image sensor, has in order from an object side: a first lens group having negative optical power; a second lens group having positive optical power; and a third lens group having positive optical power, the third lens group including at least two lenses. In magnification change from a wide-angle limit to a telephoto limit, the first lens group moves along a locus convex to an image side, the second lens group moves monotonically to the object side, and the third lens group moves along a locus convex to the object side.

Abstract: A zoom lens system comprising a first lens unit having negative power, a second lens unit having positive power and a third lens unit having positive power, wherein in zooming from a wide-angle limit to a telephoto limit, the lens units move respectively along an optical axis in such a manner that an interval between the first lens unit and the second lens unit decreases while an interval between the second lens unit and the third lens unit changes so that variable magnification is achieved, the first lens unit comprises one object side negative lens element and one image side positive lens element with a convex surface facing the object side, which have an aspheric surface, and the conditions: n12>1.88 and ?12<26 (n12 and ?12 are refractive index and Abbe number, respectively, of the image side positive lens element of the first lens unit) are satisfied.

Abstract: A method for designing and fabricating lens unit comprises the steps of: establishing a set of known parameter values of a properly focused lens unit; inputting an image height desired; calculating a corresponding lens wall thickness and an air gap based on the image height inputted; and designing and fabricating a new lens unit based on the calculated lens wall thickness and air gap to accord with the image height inputted. As such, the present invention only needs to alter the wall thickness and air gap of optical lens to obtain different image heights. The alteration of wall thickness is achieved by adjusting the space between the male and female parts of the mold assembly; the alteration of air gap is achieved by providing a pad of predetermined thickness on the optical lens without the need to redesign the mold assembly for the fabrication of optical lens.

Abstract: A subminiature imaging optical system with two lenses is provided. The optical system includes an aperture stop. A first meniscus lens has a positive refractive power, and includes aspherical surfaces at both of object and image sides. The object side of the first meniscus lens is convex. A second meniscus lens has a positive refractive power, and includes aspherical surfaces at both of the object and image sides. The image side of the second meniscus lens is convex. In addition, the first lens has a gap from the second lens according to following relation 1: 0.1<D/TL<0.2??relation 1, where D is the gap between the first and second lenses and TL is a distance from the aperture stop to an image plane. The invention ensures a high-definition subminiature imaging optical system improved in various aberrations and superior in MTF properties.

Abstract: A third holding barrel is set to a stationary work holder, and a lens frame holding an eighth lens group is set to a movable work holder. The movable work holder is moved to insert the lens frame inside the third holding barrel. In this state, a chart image through the eighth lens group is projected on a screen. While checking the center and clarity of the projected image on the screen, position of the eighth lens group is adjusted. After the position adjustment, an adhesive is injected through openings of the third holding barrel by an injector, thereby fixing the lens frame to the third holding barrel.

Abstract: A lens barrel for holding a lens system including at least a plastic lens disposed between two glass lenses separated from each other by a spacer ring comprises a cylindrical lens holding barrel fixedly holding the two glass and the plastic lenses, a cylindrical spacer ring fitted in the cylindrical lens holding barrel for elastically supporting the plastic lens therein and positioning the two glass lenses at a predetermined axial distance on opposite sides of the plastic lens.

Abstract: An optical element holding apparatus provided with a holding portion for holding a flange portion of an optical element. The holding portion includes a bearing surface block having a bearing surface, which contacts the flange portion, and a bearing surface block support mechanism, which rotatably supports the bearing surface block about a tangential axis of the optical element. This structure holds the optical element with the optical element holding apparatus in a kinematical manner and maintains satisfactory imaging performance in the optical element.

Abstract: An optical pick-up actuator includes a lens holder, a magnetic circuit, a wire spring, a wire holder, and a damper material receptacle. The lens holder includes an objective lens. The magnetic circuit moves the lens holder. The wire spring is coupled at one end thereof to a side of the lens holder, and supports the lens holder. The wire holder fixes the other end of the wire spring. The damper material receptacle defines an insert hole and a through-hole, through which the other end of the wire spring is inserted and passes. The damper material receptacle holds a predetermined damper material that absorbs vibrations imparted on the wire spring. The damper material defines an injecting hole, through which the damper material is injected, separately from the insert hole and the through-hole.

Abstract: Actuator for an optical scanning device The invention relates to an actuator for an optical scanning device, having a focus lens mounted in a lens holder and having a damper base firmly connected to a mount, having a magnet arrangement arranged on the mount, and a coil arrangement interacting with the magnet arrangement, on a printed circuit board, for fine positioning of the focus lens, with the printed circuit board being connected to the damper base by means of elastically flexible suspension means arranged on both sides of the longitudinal axis of the actuator. It achieves the object of designing an actuator such as this in such a way that it has a reduced moment of inertia, because of a reduced mass. For this purpose, the printed circuit board is at the same time a mounting board for the lens holder, and the printed circuit board and the lens holder together form the moving part of the actuator.

Abstract: A brightness enhancement film includes a substrate, a plurality of curved prism units and a plurality of light scattering particles. The curved prism units are extended in parallel and formed on a first surface of the substrate. Each of the curved prism units includes at least one meandering surface to provide with changes in curvature. Thus, the meandering surface of the curved prism unit is able to refract incident light in two dimensions with respect to the substrate that may enhance entire light-collecting efficiency in two dimensions. The light scattering particles are disposed in the curved prism units.

Abstract: A vehicular external mirror module includes a mirror housing. A mirror glass is housed within the mirror housing. The mirror glass includes a non-mirrored surface facing out of the mirror housing and a mirrored surface facing the mirror housing. The vehicular external mirror module also includes a luminescent film fixedly secured to the mirror surface of the mirror glass. The luminescent film emits light out from the luminescent film through the mirror glass.

Abstract: An arrangement for use with a micro-mechanical beam, in which a plurality of support structures are configured to directly attach to the micro-mechanical beam to increase bending stiffness of the micro-mechanical beam without significantly influencing torsional stiffness. At least two of the support structures are arranged to touch each upon reaching a predetermined bending action of the micro-mechanical beam and prevent a further bending action of the micro-mechanical beam, and at least two of the support structures are non-identical.

Abstract: The present invention relates to a syringe (1) for use in spectroscopy to identify drugs within the syringe (8). The syringe comprises a optical window section (8) either integral with or attached to the syringe (1). The optical window section (8) has predetermined physical and optical properties that allows radiation to pass through in a known manner to facilitate spectroscopy.

Abstract: A color wheel of a projector includes a red segment, a green segment, a blue segment and a white segment. The white segment is coated so as to provide color temperature of 6500K or 7000K. The red, green and blue segments are coated so as to provide full-segment transmission. The area ratio of the red segment, the green segment and the blue segment on the color wheel is designed based on the color temperature of the color wheel, so that color coordinate deviations can be reduced.

Abstract: An information reproducing apparatus which reproduces information recorded on a medium includes an asymmetry correction circuit configured to correct an asymmetry of a signal read from a medium. The apparatus also includes a first high pass filter installed before the asymmetry correction circuit and configured to remove noise in the signal by a first cut-off frequency. The apparatus also includes a second high pass filter installed after the asymmetry correction circuit and configured to remove the noise in the signal by a second cut-off frequency, wherein the second cut-off frequency is higher than the first cut-off frequency.

Abstract: An information recording and reproducing apparatus which records information on a medium and reproduces information stored on the medium includes a write compensation circuit configured to perform compensation of the information recorded on the medium, wherein the write compensation circuit corrects, in advance, an asymmetry of a signal read from the medium by correcting a write signal in a pulse form along a time axis, and an amount of correction along the time axis is based on information included in the write signal.

Abstract: According to one embodiment, a disk drive is provided which has a head amplifier having a function of, at a data recording time, outputting AC pattern data to a write head prior to the recording of the write data to allow it to be recorded on a write splice section on a disk medium. The write head records an AC signal pattern of a high frequency on the write splice section on the disk medium according to an output timing of a write gate and then write data is recorded with a preamble as a header.

Abstract: Embodiments in accordance with the present invention relate to suppressing effects of the rotational jitter of a rotating medium during self-writing of patterns on the medium. In one embodiment, patterns are written on a track TE first. While a clock frequency is modulated using the difference between the readout time and target time of each pattern PE on the track TE, patterns PF are written on a track TF after a calculated delay time from the readout of each pattern PE. During pattern writing on the track TF, any timing errors of the patterns PE are stored into memory. While the target time for each pattern PF on the track TF is being corrected using the stored timing errors of the patterns PE and the clock frequency is being modulated using the difference between the readout time and corrected target time of each pattern PF, patterns PG are written on a track TG after a calculated delay time from the readout of each pattern PF.

Abstract: A portable apparatus for reproducing audio data includes a recording medium on which the audio data is recorded, a reading head for reading the audio data from the recording medium, an acceleration sensor for detecting acceleration, a buffer memory from which the audio data is read after the audio data is once stored therein; and a processor for executing control of retracting the head from the recording medium in a case where a predetermined value of acceleration is detected by the acceleration sensor when the audio data is temporarily stored into the buffer memory from the recording medium.

Abstract: A magnetic disk apparatus-purpose reproducing circuit capable of performing a high speed and under stable condition. In the magnetic disk apparatus-purpose reproducing circuit equipped with: a bias circuit for applying a bias voltage with respect to an MR (Magneto-Resistive) head, an amplification circuit for amplifying an output of the MR head, capacitors C0 and C1 for cutting a DC component contained in the output of the MR head, and a conductor amplifier for applying an input bias of the amplifier, a shortcircuit-purpose switch S0 for charging the DC cut capacitors are further provided. When a mode transition from a write mode to a read mode occurs, the shortcircuit-purpose switch S0 is turned ON so as to charge the DC cut capacitors, so that a mode transition characteristic capable of establishing a high speed characteristic and a stable characteristic can be obtained.

Abstract: A slider of a magnetic head device has a side that faces a recording medium and on which a first positive pressure is exerted on the leading side and a second positive pressure is exerted on the trailing side. In the area between the first positive pressure area and the second positive pressure area, a small second negative pressure is created at the front, a first negative pressure larger than the second negative pressure is created at the rear, and a third positive pressure is exerted on both sides of the first negative pressure area. When air density decreases, the small second negative pressure in a middle area and the large first negative pressure at the rear of the second negative pressure area stabilize the pitch angle of the slider and prevent an excessive decrease in the flying distance of a trailing end portion.

Abstract: In an electronic appliance, accelerations in X-direction, in Y-direction that is orthogonal relative to the X-direction and in Z-direction that is orthogonal relative to both the X-direction and the Y-direction are synthesized and the size of the synthetic acceleration vector formed by synthesizing the accelerations is detected, associated with the clock time of the detection and stored in a synthetic acceleration memory (4). A fall candidate is detected when the size of the synthetic acceleration vector is stabilized at a value close to a for a predetermined time period and clock time T1 that is associated with the synthetic acceleration vector that has a size equal to predetermined value b and closest to the clock time T1 when the fall candidate is detected is determined by retrieving the sizes of the synthetic acceleration vectors stored in the synthetic acceleration memory (4).

Abstract: Methods and systems are provided for writing a magnetic servo track. In one example, a system includes a head assembly having first and second write elements, and a controller. The controller operable to receive a position signal associated with a position of the magnetic storage medium and energize the first write element to write a first magnetic servo pattern (e.g., repeating servo frames including a tone field). The controller is further operable to energize the second write element to write a second magnetic servo pattern (e.g., a mid-frame mark) at least partially overlapping the first pattern, wherein the relative position of the second pattern is adjusted in response to the position signal. The second pattern may be displaced relative to the first pattern in response to a lateral displacement of the magnetic storage medium to maintain a desired center line condition of the servo track.

Abstract: According to one embodiment, a disk drive is provided which realizes an effective variable track pitch structure of a perpendicular magnetic recording system. The disk drive uses a magnetic head including a write head having a main magnetic pole structure with a bottom surface formed to have a trapezoidal or triangular shape. Tracks are recorded by the write head on a disk medium at a variable track pitch set based on the size of the bottom surface of the main magnetic pole structure, skew angle and bevel angle.

Abstract: A hard disk drive comprising balance weight integrally coupled to a clamp is provided. The hard disk drive comprises a disk stack assembly comprising a disk, a spindle motor comprising a rotational shaft and a spindle motor hub adapted to support the disk, and a clamp comprising a plurality of installation holes. The hard disk drive further comprises at least one clamp screw and a balance weight integrally coupled to the clamp and adapted to compensate for an imbalance in the disk stack assembly.