Abstract: A method of fabricating a sub-millimeter scale curved surface on a substrate (10) includes cutting a plurality of trenches (12) of varying depth into the substrate (10). The depth of the trenches (12) corresponds to a desired surface profile. The substrate (10) is etched to remove material left (16) between the trenches to form the curved surface.

Abstract: A liquid lens includes a segmented electrode that allows the simultaneous application of different potentials across the lens's meniscus to obtain a predetermined aberration correction condition and to adjust focal length as necessary to conform to the topography of the object being scanned. The lens also includes a gas plenum interfacing with one of the liquids of the lens to allow for volume changes in the lens cell due to temperature variations. This combination of features produces a liquid-lens cell capable of maintaining substantially constant transverse magnification and diffraction-limited image quality over a useful range of focal length. As such, the lens is particularly suitable for incorporation in an array of micro-objectives used in a scanning microscope.

Abstract: A vario-astigmatic beam expander is capable of collimating an astigmatic light beam, or inducing astigmatism in a well-collimated beam, by passing the light beam through a combination of spherical and cylindrical lenses, whereby both the degree of astigmatism and the axis of astigmatism induced are continuously adjustable. The beam expander has applications in industrial laser processing systems.

Abstract: A zoom lens system includes a positive first lens group, a negative second lens group, and a rear lens group which is provided on the image side of the negative second lens group, and has a combined positive refractive power, in this order from the object; and the zoom lens system satisfies the following conditions: 5.0<f1/fw<6.5 ??(1) 0.4<fRt/ft<0.55 ??(2) wherein f1 designates a focal length of the positive first lens group; fw designates a focal length of the entire the zoom lens system at the short focal length extremity; fRt designates a combined focal length of the positive rear lens group at the long focal length extremity; and ft designates a focal length of the entire zoom lens system at the long focal length extremity.

Abstract: A zoom lens system includes a negative first lens group, a positive second lens group, and a positive third lens group. Each of the first to third lens groups is moved along the optical axis to perform zooming. The first lens group includes a negative lens element, a negative lens element and a positive lens element. The second lens group includes a positive lens element, a positive lens element and a negative lens element. A combined refractive power of the image-side positive lens element and the negative lens element is negative, and these lens elements are cemented to each other. The third lens group includes a positive lens element and a negative lens element which are cemented to each other, in this order from the object. The zoom lens system satisfies the following condition: 1.2<f2G/f21<2.0 ??(1) wherein f2G: a focal length of the second lens group; and f21: a focal length of the most object-side positive lens element in the second lens group.

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: the first lens unit comprises a first lens element having a concave surface at least on the image side and negative power and a second lens element having a convex surface at least on the object side and positive power; the second lens unit comprises a single third lens element, a cemented lens element of two lens elements having power of mutually different signs and a single sixth lens element; in zooming, all of the lens units move along an optical axis; and conditions (1): 5.0<?iW<20.0 and (I-2): n11?1.9 (where, 3.

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: the first lens unit comprises a first lens element having a concave surface at least on the image side and negative power and a second lens element having a convex surface at least on the object side and positive power; the second lens unit comprises a cemented lens element fabricated by two lens elements having optical power of mutually different signs and one single lens element; in zooming, all of the lens units move along an optical axis; and conditions (1): 5.0<?i W<20.0 and (I-2): n11?1.9 (where, 3.

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: the first lens unit comprises a first lens element having a concave surface at least on the image side and negative power and a second lens element having a convex surface at least on the object side and positive power; the second lens unit comprises a first cemented lens element of two lens elements having power of mutually different signs and a second cemented lens element of two lens elements having power of mutually different signs; in zooming, all of the lens units move along an optical axis; and conditions (1): 5.0<?iW<20.0 and (I-2): n11?1.9 (where, 3.

Abstract: The present invention provides a side emitting lens that may reduce optical loss and improve light emitting ratios, and a backlight unit and liquid crystal display including the side emitting lens. The side emitting lens may have a substantially dome-shaped body. The body includes a base part on which external light is incident, a refracting part to refract incident light and emit the light from side surfaces, and a reflecting part. The reflecting part is in the shape of a conical recess at a central portion of the refracting part to fully reflect the incident light toward one of the refracting part and the base part and the reflecting part comprises two or more reflecting surfaces. Each of the two or more reflecting surfaces is a curved surface.

Abstract: In a bonded optical element, a second optical element is bonded to a first optical element by forming the second optical element by heating and pressing against the first optical element a second optical element material. The first optical element is a concave lens. A bonded face of an intermediate portion between a lens potion and an edge portion of the first optical element is substantially in an R shape in section.

Abstract: In a bonded optical element, a second optical element is bonded to a first optical element by forming the second optical element by heating and pressing against the first optical element a second optical element material. The second optical element includes an element body part and a contact part extending from the element body part to be in contact with the outer peripheral face of the fist optical element.

Abstract: An optical axis tilting device of a laser optical system, includes a lens barrel inside of which provided with a laser optical system; a tilt frame supported at the lens barrel; a tilt sensor which is provided at the tilt frame and is configured to detect a preset reference position of the tilt frame; a fixed frame fixed to the lens barrel and provided with a tilting mechanism which tilts the tilt frame relative to a horizontal plane; a leveling mechanism which supports the lens barrel tiltably, and tilts the lens barrel so as to detect the reference position by the tilt sensor and then levels the tilt frame; a feed screw which is rotatably driven by a driving motor; a feed piece which is reciprocated by the feed screw and engages with the tilt frame and tilts the tilt frame relative to the reference position; a piece position detection device configured to detect a position of the feed piece; and a computing device configured to calculate a tilting angle based on the position of the feed piece detected by th

Abstract: A lens unit including a lens barrel for receiving at least one lens, a motor arranged to displace the lens barrel between an initial position and a maximum displacement, wherein the displacement of a lens barrel is proportional to the level of an electrical signal applied to the motor when the electrical signal is between first and second levels, the first level corresponding to a level for starting movement of the lens barrel from the initial position and the second level corresponding to a level for bringing the lens barrel to the maximum displacement; a first conductor fixed to the lens barrel and arranged to make electrical contact with a second conductor when said lens barrel is at one of said initial position and said maximum displacement; and a processor arranged to detect a change in the contact situation between the first and second conductive surfaces, to determine one of said first and second levels based on level of the electrical signal at the time of the change and to generate, based on said det

Abstract: There are provided a piezoelectric actuator and a lens driving apparatus having the piezoelectric actuator. The lens driving device includes: a lens barrel having a lens hole where at least one lens is disposed, and having a tip friction member on an outer surface thereof; a base having a guiding part guiding the lens barrel to move along an optical axis direction; a piezoelectric actuator having a piezoelectric body disposed at an edge of the base to apply a driving force when a power is applied, the piezoelectric body having at least one friction member at one side thereof to be in contact with the tip friction member; and a preload member applying an elastic force for elastically supporting the piezoelectric actuator against the lens barrel to keep the tip friction member and the friction member in contact with each other.

Abstract: A small-sized lens barrel and camera have the following configuration. The lens barrel has a first barrel, a second barrel movable between retracted position retracted in the inner diameter side of the first barrel and shooting position shifted toward the incident side in an optical axis direction with respect to the first barrel, a lens moved relative to the second barrel, a support part formed into a ring shape and supported by the end of the first barrel on the exit side in the optical axis direction, the support part being arranged on the inner diameter side of the first barrel, a projecting part formed so as to project in the optical axis direction from the end of the second barrel on the exit side in the optical axis direction, and an accommodating part being formed at the support part and accommodating the projecting part at the retracted position.

Abstract: An exemplary camera module includes a lens module and a lens holder. The lens module is coupled with the lens holder using threads. The thread coupling section between the lens module and the lens holder is filled with a damping oil for sealing the thread coupling section.

Abstract: A movement preventing structure for a color separation prism prevents or reduces the movement in an optical axis direction of the color separation prism caused by the thermal expansion or contraction of a color separation prism supporting member.

Abstract: In a vehicle outside mirror device, a gear case of a casing has an engagement portion with which a shaft bearing member engages so as not to be movable in a direction orthogonal to an axial direction of a shaft. In addition, the gear case and a cover of the casing include a fixation portion that sandwiches the shaft bearing member in the axial direction of the shaft and fixes the shaft bearing member.

Abstract: An optical device includes a structure defining an enclosed volume that is empty or filled with a non-solid, such as an aerogel or a gas, within which reflective surfaces bounce incoming light back and forth, focusing the light toward an exit aperture. The structure of the device may be formed from two halves, which are molded or machined to form the inner faces used to reflect and focus incoming light. The structure halves may be made of a moldable material. The moldable material may have reflective material, such as aluminum, deposited on inner faces that are used to reflect and focus incoming light. The halves of the structure are joined together, such as by use of a suitable adhesive. The enclosed volume may be substantially empty except for an ambient gas. The resulting hollow optical device provides a greatly reduced weight compared with folded optics made from solid materials.

Abstract: A device for a vehicle including a support, a control on the support, the control actuatable by a user to control movement of a rear-view mirror, and a selector on the support, the selector being actuatable by the user to select between: a first mode of controlling the rear-view mirror whereby the movement of the rear-view mirror is controlled by the control, or a second mode of controlling the rear-view mirror whereby the movement of the rear-view mirror is controlled by another mechanism not located on the support.

Abstract: Security rearview mirror for the opening of the vehicle rear door, set to show the outer, side and back area of a car while proceeding with the opening of the rear door by the occupant of the back part of the vehicle.

Abstract: Element for the protection and therapy of eyes applied to the transparent vertical surfaces of buildings. The invention is prepared by applying a yellow pigmented filter to the transparent or translucent surfaces of a building in which a subject may be found, and is designed to protect the eyes from the short wavelengths of the visible spectrum in the range 500 to 380 nm. The invention avoids the difficulties and risks of existing ways of protecting healthy eyes or eyes subjected to cataract surgery, and improves the protection of eyes suffering neurodegeneration, simply by applying a filter to the transparent or translucent surfaces of any building in which a subject may be found to provide protection against the neurodegenerative components of light (short wavelengths).

Abstract: This invention decreases a spectral reflectance in the entire visible wavelength range, to decrease inconveniences in an image such as flare or ghost. A non-reflective periodic layer including a large number of fine uneven periodic structure bodies is formed on a substrate, and an ND film is formed on the other surface of the substrate by vacuum deposition, to improve an anti-reflection function. Regarding a beam entering the ND filter, the MgF2 film of the formed ND film suppresses the spectral reflectance at the boundary of the atmosphere and the ND film and at the boundary of the ND film and the substrate. The non-reflective periodic layer decreases the reflectance at the boundary of the substrate and the atmosphere.

Abstract: An exemplary color wheel assembly comprises a carrier, a locking member, a color filter unit and an elastic member. The carrier includes a main body, a shaft and a lock-receiving portion. The shaft coaxially protrudes outwardly from the main body. The lock-receiving portion is defined in the shaft. The locking member is lockingly received in the lock-receiving portion. The color filter unit is disposed on the main body. The elastic member is interposed between the locking member and the color filter unit and is compressed therebetween to push the color filter unit against the main body. In this way, the color filter unit is firmly fixed on the main body and the color wheel assembly is assembled.

Abstract: An optical actuator is disclosed. The optical actuator includes a seat bearing the optical element, a yoke comprising an end, a suspension system comprising at least one spring sheet connecting the seat and the end, and a driving device moving the seat relative to the yoke. The spring sheet constrains the movement of the seat. The spring sheet includes an inner connecting portion connected to the seat, an outer connecting portion surrounding the inner connecting portion and connected to the end, and a spring structure disposed between the inner and outer connecting portions and connecting the inner and outer connecting portions.

Abstract: If a large minimum data unit for recorded data is used to record a small data amount of management information, the recording time is long, and furthermore when a WO (write once) is used as the recording medium, the number of recording operations which can be performed is restricted. To solve the above problems, the present invention can record data in a management area in units smaller than ordinary units for recorded data to suitably record information in a limited management area and thereby efficiently use the user data area. At that time, the present invention simplifies interleave processing usually applied to ordinary recorded data, and performs the simplified interleave processing on a data structure (for data of small size) of the present invention so as to ensure the signal processing compatibility between the ordinary data and data having the data structure according to the present invention.

Abstract: According to one embodiment, a disk drive that effectively corrects data errors, which are changes in the total number of data bits at the time of reproducing the data. The disk drive has a disk and a disk controller. The disk has a data-recording area constituted by a set of magnetic dots that are physically separated from one another. The disk controller uses error-correcting codes, determining an error that shows a change in the total number of bits in a data-bit string of the data set reproduced.

Abstract: Provided are a read channel, storage drive and method using a measured error to determine coefficients to provide to an equalizer to use to equalize an input signal. A read channel is incorporated in a storage device to process signals read from a storage medium. An equalizer uses coefficients to equalize input read signals to produce equalizer output signals. A detector processes adjusted equalizer output signals to determine output values comprising data represented by the input read signals. An equalizer adaptor is enabled to provide a reference measured error and coefficients used to produce the adjusted equalizer signals that are associated with the reference measured error. The equalizer adaptor computes new equalizer coefficients to use to equalize input read signals that result in a new measured error from the detector and computes a new measured error for the new equalizer coefficients.

Abstract: A hard disk drive with a disk that has a servo field with an A servo burst and a B servo burst. The A servo burst has a trimmed erase band. The trimmed erase band can be created by offsetting the write head relative to a burst centerline to reduce the width of the erase band. For example, the write head can be moved toward a centerline of the A servo burst. The offset can be a function of write current and cylinder location of the disk. The offsets are selected so that the resultant burst profiles do not contain a flat minimum portion.

Abstract: The present invention predicts and diagnoses damage to a read head element of a magnetic head used in a magnetic storage device. The present invention includes a control circuit for implementing a write data protection operation and for implementing a write and read operation using a different magnetic head when damage to the read head element is predicted, so as to allow detection of write data using a read element of a different magnetic head. The control circuit includes a monitor configured to detect a voltage of a read head element of a magnetic head, a comparator that determines whether the detected voltage exceeds a threshold voltage, the threshold voltage preferably being less than a maximum tolerable voltage of the read head element, and a counter configured to count signals passing through the comparator.

Abstract: According to one embodiment, in a disk drive having a disk and a flash memory, the disk controller controls the timing of performing a block erase when the flash memory is accessed, so that this timing may differ from the timing of a seek operation that is performed when the disk is accessed. This prevents the current flowing in the disk drive from exceeding the maximum operating current.

Abstract: A data recording apparatus of the present invention includes a head that records data signals by magnetizing a magnetic tape 10 and a recording control portion that controls the recording operation by causing recording current to flow to the head. The recording control portion controls the operation of the head, so that in the magnetic tape 10, which is direct current demagnetized continuously in the longitudinal direction, a magnetic field is formed intermittently in an opposite direction to the magnetization direction of the direct current demagnetization. Thus, when recording data signals on the magnetic recording medium, it is possible to make the current flowing to the head small and to realize apparatus power consumption reductions, load reductions for the head and circuitry, and reduction in crosstalk noise from the head chip used for writing to the head chip used for reading.

Abstract: Embodiments in accordance with the present invention provide a drive unit that is capable of satisfactorily performing the positioning control with disturbance components included in a position error signal being effectively controlled. According to one embodiment, an error signal generator of a drive unit generates a position error signal (PES) on the basis of servo data read out from a magnetic disk. On the assumption that a frequency of a periodic variation component included in the PES is a target frequency, if a target frequency deviates from an effective frequency range of a digital filter, a downsampler down-samples the PES, and then supplies the PES to the digital filter so that the effective frequency range is shifted. As a result, within the shifted effective frequency range, a setting changing unit can control a setting frequency of the digital filter so that the setting frequency follows the target frequency.

Abstract: The present invention discloses a hard disk drive head loading and unloading device, including a working division and a positioning division. The working division and the positioning division are fixedly connected or integrated as a whole, the former being provided with a slide rail on which a magnetic head can move, the latter a structure for mounting and positioning. The positioning division has an underside and two side faces, the underside being flat, the side faces having positioning bulges protruding from their surfaces, respectively; and the underside and the positioning bulges constitute the positioning structure of the head loading and unloading device.

Abstract: A grooved cam plate for vertically moving a roller as a crank pin is provided to move the roller vertically correspondingly to a movement of a movable table by slipping the roller in and slipping the roller up from the groove of the camp plate. A disk is reversed by the rotation of a chucking mechanism due to a half rotation of a crank shaft by the vertical movement of the roller.

Abstract: A perpendicular magnetic recording (PMR) head is fabricated with a pole tip shielded laterally by a separated pair of bottom side shields and shielded from above by an upper shield. The bottom side shields surround a lower portion of the pole tip while the upper portion of the pole tip is surrounded by non-magnetic layers. The bottom shields and the non-magnetic layer form wedge-shaped trench in which the pole tip is formed by a self-aligned plating process. The wedge shape is formed by a RIE process using specific gases applied through a masking layer formed of material that has a slower etch rate than the non-magnetic material or the shield material. A masking layer of Ta, Ru/Ta, TaN or Ti, formed on a non-magnetic layer of alumina that is formed on a shield layer of NiFe and using RIE gases of CH3OH, CO or NH3 or their combinations, produces the desired result. A write gap layer and an upper shield is then formed above the side shields and pole.

Abstract: A perpendicular recording head for a hard disk drive. The head includes a non-magnetic backside shield that minimizes or eliminates the flow of backside flux through the head. The head can be fabricated by forming a non-magnetic backside shield layer on a main pole. Portions of the backside shield and main pole can be removed to form a tapered pole portion. A non-magnetic write-gap layer and write shield are then formed onto the backside shield and main pole.

Abstract: The present invention provides a magnetic disk in a discrete track medium and a patterned medium, which prevents the loss of the magnetically recorded data when a head of a magnetic disk device contacts the magnetic disk, and a manufacturing method thereof. A magnetic disk has a protrusion as a non-magnetic member formed on a disk surface to prevent a head from being in contact with a recording section. When the protrusion formed in a disk substrate collides against the head, the protrusion 7 does not collapse, and accordingly, the recording layer is not damaged. Alternatively, concave and convex portions are formed on the substrate surface to use the convex portion as the protrusion.

Abstract: A suspension for a HGA includes a flexure having a tongue region and an out trigger. The out trigger has a pair of rigid beams and a pair of spring beams. The pair of spring beams enables the flexure to possess favorable flexibility and assists a slider to have enough displacement. The pair of rigid beams provides the flexure enough stiffness which not only successfully prevents the HGA with the out trigger from suspension deformation and dimple separation, but also assists to improve shock performance of the HGA. Furthermore, such configuration of the suspension provides the slider a good static performance and thus improves dynamic performance of the HGA. The present invention also discloses a HGA with the suspension, a manufacturing method of the HGA, and a drive unit with such HGA.

Abstract: When a piezoelectric element is deformed in the direction of decreasing a flying height, a pressure at a trailing pad increases, and the flying height of a magnetic head is not efficiently decreased and may be increased conversely in some occasions. A position of contact between a suspension and a dimple is set toward a leading edge with respect to a piezoelectric element, and a pad for generating a positive pressure is disposed between the dimple and the piezoelectric element in addition to a trailing pad. Fluctuations of a positive pressure generated toward the leading edge with respect to the dimple are thus suppressed when the piezoelectric element is deformed.

Abstract: The magnetic signal reproduction system comprises a magnetic recording medium comprising a magnetic layer comprising a ferromagnetic powder and a binder on a nonmagnetic support; and a reproduction head, wherein a number of protrusions equal to or greater than 10 nm in height on the magnetic layer surface, as measured by an atomic force microscope, ranges from 50 to 2500/10,000 ?m2, a quantity of lubricant on the magnetic layer surface, denoted as a surface lubricant index, ranges from 0.5 to 5.0, a surface abrasive occupancy of the magnetic layer ranges from 2 to 20 percent, and the reproduction head is a magnetoresistive magnetic head comprising a spin-valve layer.

Abstract: In a perpendicular magnetic recording head comprising a main magnetic pole layer and a return yoke layer which have respective front end faces exposed at a surface opposing a recording medium and are laminated with a nonmagnetic material layer interposed therebetween on the medium-opposing surface, an end magnetization control layer for generating an exchange-coupling field is provided on the upper or lower side of both end parts in a track width direction of the return yoke layer. The exchange-coupling field fixes magnetization in the end parts to the track width direction.

Abstract: To provide a thin-film magnetic head which suppresses PE while securing magnetic recording capability by controlling a domain of a leading end part of a main magnetic pole layer. The first flare part has a first flare angle smaller than a second flare angle of the second flare part. The second flare angle is smaller than 90°. The auxiliary yoke layer has a flare angle not smaller than the first flare angle but not greater than the second flare angle. The length h from the medium-opposing surface of the pole straight part to the end on the deeper side in the height direction of the first flare part satisfies the following conditional expression: h×Bs<0.000008[m·T] where Bs is the saturated magnetic flux density of the main magnetic pole layer.

Abstract: A magnetic head includes: a coil; a pole layer; a shield having an end face located in a medium facing surface forward of an end face of the pole layer along a direction of travel of a recording medium; a gap layer between the shield and the pole layer; and a substrate on which the foregoing elements are stacked. The top surface of the pole layer includes: first and second portions with a difference in height therebetween; and a third portion connecting the first and second portions to each other. The first portion has an edge located in the medium facing surface, and the second portion is located farther from the medium facing surface and from the substrate than the first portion. The magnetic head further includes a nonmagnetic layer disposed between the second portion and the gap layer. The nonmagnetic layer has a surface touching the second portion, the surface having an edge located at the boundary between the second and third portions.

Abstract: A magnetic sensor includes a plurality of giant magnetoresistive elements, each of which includes a free layer, a conductive layer, and a pin layer sequentially laminated on a substrate, wherein the pin layer formed by sequentially laminating a first magnetic layer, an Ru layer, a second magnetic layer, and an antiferromagnetic layer is subjected to magnetization heat treatment so as to fix the magnetization direction thereof. The first and second magnetic layers differ from each other in thickness and magnetic moment thereof, and the thickness of the Ru layer ranges from 4 ? to 10 ?. The magnetization heat treatment is performed so as to maintain an anti-parallel state between the first and second magnetic layers. In order to detect magnetic fields in three-axial directions, one giant magnetoresistive element is formed using a planar surface, and the other giant magnetoresistive elements are formed using respective slopes on the substrate.

Abstract: A device includes a pair of individual sensors spaced apart from each other. A current source provides current to both of the individual sensors. A differential temperature sensor is coupled thermally proximate the individual sensors and provides a temperature difference signal that is combined with current from the current source to provide a correction factor for a temperature gradient across the individual sensors. Alternatively, temperature responsive excitation sources may be positioned thermally proximate the sensors to provide temperature compensation.

Abstract: A method of electronic ballast protection including providing an electronic ballast having an AC/DC converter 104 with an electronic ballast input and a mains voltage connection 103 connectable to a mains voltage 102, an inverter 120 operably connected to the AC/DC converter 104 and having an electronic ballast output 125 connectable to a lamp 124, a control circuit 116 controlling the inverter 120, and a low voltage power supply 114 providing low voltage power to the control circuit 116; supplying power to the low voltage power supply 114 from the electronic ballast input when the mains voltage connection 103 is wired to mains voltage 102; and disconnecting the power to the low voltage power supply 114 when the electronic ballast output 125 is wired to the mains voltage 102.

Abstract: A system and method for controlling an over current protection trip point for a voltage regulator includes an input for receiving a monitored operating parameter of the voltage regulator. Control logic responsive to this input generates a digital current control signal. A digital to analog controller converts the digital current control signal to an analog current control signal and this analog current control signal is used for controlling a current source for generating a current that establishes the over current protection trip point of the voltage regulator.

Abstract: When a failure of an electric current flow occurs in any one of phases, a microcomputer calculates a d-axis current command value that changes along a tangent curve with predetermined rotation angles as asymptotic lines. The microcomputer continuously outputs a motor control signal using two phases other than the phase with the failed electric current as electric current flowing phases by performing current feedback control in correspondence with the d-axis current command value. In such two-phase drive operation, the microcomputer calculates the d-axis current command value and a q-axis current command value in such a manner that the phase current values of the electric current flowing phases become constant at respective maximum values of flowable electric currents, which are set for the phases, in rotation angle restriction ranges in which the phase current values need to be restricted in correspondence with the maximum values, or electric current restriction ranges.

Abstract: A motor driving circuit comprising: a synchronous rectification driving circuit to carry out synchronous rectification, to energize a driving coil connected between a first connection point at which a first source and first sink side transistors are connected in series and a second connection point at which a second source and second sink side transistors are connected in series; a backflow detecting resistor connected to electrodes of the first and second sink side transistors, the electrodes being on an opposite side of the first and second sink side transistors to the first and second connection points; a backflow detecting comparator to output a comparison signal indicating a result of comparison of voltage between a first and second terminals of the backflow detecting resistor, and a backflow prevention circuit to prohibit the synchronous rectification when the comparison signal indicates that the second terminal is higher in voltage than the first terminal.