Abstract: A method can include placing a substrate over a chucking region, wherein the substrate has a primary surface; quantifying a distortion in the substrate, the lithographic template, the imprint apparatus, or any combination thereof; and dispensing a formable material based at least in part on the distortion. The distortion can include a deviation in planarity, a magnification or orthogonality error or the like. In another aspect, an imprint apparatus can include a substrate holder including a chucking region; a template having an imprint surface that includes protrusions, wherein the protrusions define a primary surface; and a processor configured to determine an amount of a formable material to dispense in a particular area based at least in part on an distortion in the substrate, the lithographic template, the imprint apparatus, or any combination thereof.
Abstract: An image encoding apparatus which encodes an image includes a first acquiring unit configured to acquire an evaluation value for a block being a division of the image, a determining unit configured to determine a class to which the block belongs to among a plurality of classes based on the evaluation value acquired by the first acquiring unit, a second acquiring unit configured to acquire count information describing the number of blocks belonging to a predetermined class of the plurality of classes, and a setting unit configured to set a quantization parameter usable for encoding a block belonging to a different class from the predetermined class based on the count information acquired by the second acquiring unit.
Abstract: A control method for an information processing apparatus includes transmitting, by a first communication unit, information about an access point to which a second communication unit is connected, to a communication apparatus to which the first communication unit is connected. In a case where the information about the access point to which the second communication unit is connected is received, the communication apparatus connects to and communicates with the access point to which the second communication unit is connected by the second wireless communication method.
Abstract: A communication apparatus comprises a first communication unit that communicates with an external apparatus and to share, with the external apparatus, first and second communication parameters for establishing a communication with the external apparatus using a second communication unit that communicates with the external apparatus using the first communication parameter set by the user operation or the second communication parameter shared by the first communication unit; a holding unit that holds the communication parameter used in the communication with the external apparatus using the second communication unit; and a control unit that controls the holding unit, in the case where the holding unit holds the second communication parameter, to hold the second communication parameter so that the second communication parameter is distinguished from the first communication parameter that is set based on the user operation.
Abstract: A communication apparatus comprises a first obtaining unit configured to obtain from another communication apparatus information indicating a type of a service that can be executed by using a first communication unit, by using a second communication unit whose power consumption is less than the first communication unit; a second obtaining unit configured to, using the first communication unit, obtain from the another communication apparatus detail information necessary for performing a service indicated by the information obtained by the first obtaining unit; and a control unit configured to perform the service using the first communication unit based on the detail information obtained by the second obtaining unit.
Abstract: A position detector, including: a scale including a pattern array formed cyclically in a movement direction, the scale being provided to a fixed member or a movable member; a detector including detection elements arranged in the movement direction, the detector being provided to the other; a generating unit that selectively generates, from signals received from the detection elements, a first signal obtained by a first combination of the signals or a second signal obtained by a second combination of the signals; an output unit that outputs the first or second signal received from the generating unit; and a switcher that switches over between the first and second signals as a signal to be generated, wherein the first signal changes within a first range, corresponding to a relative position; and the second signal does not change beyond a second range smaller than the first range, corresponding to the relative position.
Abstract: A solid-state imaging device includes a photoelectric conversion unit including one microlens and a plurality of photoelectric conversion elements, a read-out circuit unit configured to read out a first signal based on charges accumulated by one of the photoelectric conversion elements and a second signal based on charges accumulated by another one of the photoelectric conversion elements, and a signal processing unit configured to, in a case where the first signal is larger than a predetermined saturation signal level and the second signal, correct the first signal to a predetermined signal level based on the second signal so that a change rate of a third signal obtained by adding the first and second signals relative to a light amount approximates to the change rate in a case where the first signal is smaller than the predetermined saturation signal level.
Abstract: A liquid container mounted on a recording apparatus and containing a liquid in a liquid containing portion, including a first surface which faces the recording apparatus when the liquid container is mounted on the recording apparatus, and a second surface opposite to the first surface, wherein the liquid containing portion has, on a bottom surface which is a lower surface in a gravity direction when the liquid container is mounted on the recording apparatus, a first inclined surface inclining downward in the gravity direction from the first surface side to the second surface side and a second inclined surface inclining upward in the gravity direction from the first surface side to the second surface side in this order from the first surface side.
Abstract: The liquid ejection apparatus includes a circulation unit configured to circulate a liquid along a circulation passage extending from a liquid supply source to the liquid supply source through a liquid ejection head. Further, the liquid ejection apparatus includes a deaeration unit configured to perform a deaeration operation of decreasing a dissolved gas amount of the liquid, a recovery unit configured to recover ejection performance of an ejection opening, and a control unit configured to control an operation of driving the circulation unit and the deaeration unit. The control unit starts the deaeration operation and circulates the liquid having been deaerated by the deaeration operation inside a circulation path after the recovery operation and before an initial printing operation after the recovery operation.
Abstract: Provided is a zoom lens, including, in order from an object side to an image side: a first lens unit having a positive refractive power; a second lens unit having a negative refractive power; a third lens unit having a positive refractive power; a fourth lens unit having a positive refractive power; a fifth lens unit having a negative refractive power; and a sixth lens unit having a positive refractive power, in which an interval between the first lens unit and the second lens unit is increased during zooming from a wide angle end to a telephoto end, an interval between adjacent lens units is changed during zooming, and the lens shapes of lenses included in the first lens unit are appropriately set.
Abstract: An image processing apparatus includes a tomographic image acquisition unit configured to acquire a polarization-sensitive tomographic image of a subject, and an extraction unit configured to extract, from the polarization-sensitive tomographic image of the subject, a region in which a polarization state is scrambled.
Abstract: A print control method that is capable of canceling the unprintable state without troubling a user. An image forming apparatus performs a print process according to print data transmitted from an information processing apparatus by the print control method. An anomaly detection step detects anomaly in a print related process, which is relevant to the print process, under execution by the information processing apparatus. A state shifting step stops the print process under execution by the image forming apparatus, and makes the image forming apparatus shift to a printable state for preparing a new print process that is different from the print process that the image forming apparatus is executing when anomaly is detected in the print related process. A reboot step reboots the information processing apparatus in response to the shift of the image forming apparatus to the printable state.
Abstract: An ink jet recording method comprising ejecting an ink from a recording head to record an image on a recording medium using an ink jet recording apparatus. The ink jet recording apparatus includes a main tank having an air communication part, a sub tank, and a recording head. The ratio of the maximum ink storage amount of the main tank to the maximum ink storage amount of the sub tank is 3.0 or more to 50.0 or less. The temperature of the ink in the sub tank is higher than the temperature of the ink in the main tank. The ink contains a coloring material and a particular surfactant.
Abstract: An information processing apparatus comprises an image capturing unit configured to output a maximum tone value for each tone point at which exposure exceeds a saturation light amount; a calculation unit configured to calculate individual tone intersections by interpolating tone distributions of a first and second luminance pattern lights that were output by the image capturing unit; and a light quantity adjustment unit configured to adjust the quantity of light that enters the image sensor such that the tone values of tone points that are adjacent to the tone intersections and are used in calculation of the individual tone intersections are lower than the maximum tone value, and the tone value of at least one tone point other than the adjacent tone points is equal to the maximum tone value.
Abstract: A liquid ejection head includes a liquid ejection board and a liquid ejection head component disposed on the liquid ejection board. The liquid ejection board includes a substrate, an energy generating device on the substrate, a channel defining member defining a liquid channel and having a liquid ejection opening in communication with the liquid channel, a liquid supply passage in communication with the liquid channel, a liquid supply opening in communication with the liquid supply passage and having a smaller opening cross-sectional area taken in a direction perpendicular to a flow direction of a liquid than the liquid supply passage, and an opening in communication with the liquid channel. The liquid channel allows a liquid to be in contact with the energy generating device. The liquid ejection opening allows a liquid to be ejected therethrough. The liquid ejection head component closes at least a portion of the opening.
Abstract: A belt feeding device includes a belt, a first roller, an opposing roller, a second roller, and a brush roller. (|D2s?D2m|/2)×10???(|D2s?D2m|/2)×(b/(a+b)) is satisfied, where D2m is a minimum diameter of the first roller, D2s is a maximum diameter of the first roller, ? is an entering amount of the opposing roller into the brush roller with respect to a reference line A between a portion of the first roller having the minimum diameter D2m and the second roller, a is a distance between a line passing through a rotation center of the first roller and a line passing through a rotation center of the opposing roller, and b is a distance between a line passing through a rotation center of the second roller and a line passing through the rotation center of the opposing roller.
Abstract: An image processing apparatus has: a depth map acquiring unit configured to acquire a depth map that records information indicating a depth distance corresponding to each point on a photographed image; an in-focus position acquiring unit configured to acquire an in-focus position on the photographed image; a reference distance determining unit configured to acquire a depth distance corresponding to the in-focus position from the depth map and sets the acquired depth distance as a reference distance; and an image processing unit configured to perform image processing on the photographed image by using the depth map and the reference distance.
Abstract: Provided is a cleaning blade including: an elastic member; and a supporting member supporting the elastic member. The elastic member includes a free end portion, and the free end portion has an edge and a first surface and a second surface that form the edge. At least one of the first surface and the second surface has a hardened surface. The following expression (1): 0.1?DHs?0.4 and the following expression (2): DHs<DHm are satisfied, where DHs (mN/?m2) represents a dynamic hardness of the hardened surface, and DHm (mN/?m2) represents a maximum value of the dynamic hardness obtained in a positional range in which a distance L from the edge on a straight line that bisects an angle of the edge in a cross-section of the elastic member orthogonal to a longitudinal direction thereof satisfies 0 ?m<L?100 ?m.
Abstract: A distance between a plurality of discharge orifice rows that discharge ink having a high permeation speed at a plurality of recording parts is made to be shorter than a distance between a plurality of discharge orifice rows that discharge ink having a low permeation speed at a plurality of recording parts.
Abstract: An image forming apparatus includes a movement member arranged to move a cartridge and is movable between a first position for disposing the cartridge at a position where image formation is possible and a second position where the cartridge is attachable to and detachable from the movement member. At least one coupling provided in the cartridge is, when the movement member is at the first position, moved to a drive position where the coupling is arranged to engage with a drive member to rotate at least one rotating member, and while the movement member is being moved from the second to first positions, the at least one coupling is at an inclined position.
Abstract: A sheet conveying apparatus includes a pair of first conveying rollers, a pair of second conveying rollers provided at a downstream of the pair of first conveying rollers in a conveying direction of a sheet, a loop being formed in the sheet when a head of the sheet conveyed by the pair of first conveying rollers butts against the pair of second conveying rollers, and a controller which executes a first control mode in which the sheet is conveyed by the pair of first conveying rollers and the pair of second conveying rollers without dissolving the loop formed in the sheet, or a second control mode in which the loop formed in the sheet is dissolved, and the sheet nipped by the pair of first conveying rollers and the pair of second conveying rollers is conveyed.
Abstract: A cartridge detachably mountable to an image forming apparatus including a main assembly and a detachably supported supporting member movable between a first position where the cartridge is provided at an image formable position, and a second position retracted from the first position. The cartridge includes a supported portion for being supported by contacting with a supporting portion provided in the supporting member when the supporting member is in the second position, and a suppressed portion for suppressing rotation of the cartridge about the supported portion by engaging with a suppressing portion in the supporting member when the supporting member is in the second position. When the supporting member is at the first position, the supported portion is spaced from the supporting portion and the suppressed portion is spaced from the suppressing portion.
Abstract: This invention employs an object information acquiring apparatus including a probe for receiving, as a received signal, an acoustic wave which is generated within an object irradiated with light and propagates on an object surface, and a processor for generating object information, which is information based on an internal optical characteristic value of the object, by using intensity of the received signal. The processor corrects the intensity of the received signal by using the reflectance upon the acoustic wave entering the probe which is calculated based on the angle of the acoustic wave entering the probe, and on the acoustic impedance and acoustic velocity of the object and the probe.
Abstract: A cartridge that can be inserted in an apparatus main body of an image forming apparatus by moving along an axial direction of an image bearing member includes the image bearing member, a frame configured to support the image bearing member, a storage member configured to store therein information on the cartridge, and include an electrical contact, and a first pressed section and a second pressed portion configured to be pressed by the apparatus main body. The electrical contact is disposed between the first pressed section and the second pressed section, and is configured to be in contact with the main body contact on a lower side in a state where the cartridge is attached to the apparatus main body.
Abstract: According to an aspect of the present invention, there is provided a sheet processing device including a first teeth portion, a second teeth portion that clamps and binds a sheet bundle with the first teeth portion, a first support portion supporting the first teeth portion, a shaft, and a second support portion supporting the second teeth portion. The second support portion includes first and second arm members integrally supported to be capable of swinging around the shaft between a binding position in which the second teeth portion clamps and binds the sheet bundle with the first teeth portion and a standby position in which the second teeth portion is apart from the first teeth portion. The second arm member is provided over the first arm member so as to cover a part of the first arm member.
Abstract: A developer container includes a developer containing portion capable of containing a developer, a discharge port through which the developer contained in the developer containing portion is discharged, and a storing portion configured to store the developer to be discharged through the discharge port. The storing portion is in fluid communication with an inside of the developer containing portion and the discharge port. In addition, a displacement portion is provided in the storing portion and arranged to be displaceable, and includes a displaceable shaft portion configured to extend along the storing portion and a coil spring which biases the displaceable shaft portion. A rotatable member is provided above the storing portion and has first and second portions arranged in a rotational direction of the rotatable member, the first portion being contactable to a part of the shaft portion and the second portion not being contactable to the shaft portion.
Abstract: An image forming apparatus includes a main assembly; a door; a discharging portion provided in the main assembly and provided with a first opening for discharging toner; and a toner receptor detachably mounted to the door to accommodate the toner, the toner receptor being provided with a second opening cooperative with the first opening to form a toner flow passage, wherein the receptor is movable, in a state that it is mounted on the door, between a contacting position in which the receptor contacts the discharging portion such that the second opening is in fluid communication with the first opening and a spacing position in which the receptor is spaced from the discharging portion, and wherein the receptor mounted on the door is movable between the contacting and the spacing positions in a direction inclined with respect to a contact plane of the discharging portion relative to the receptor.
Abstract: A system control unit displays, on a display unit, a menu screen corresponding to an operation mode designated through a mode change-over switch, and sets various conditions for the operation mode according to operation on an operation unit. The system control unit displays a predetermined menu item in a selected state on an initially opened menu screen. When a menu screen subjected to setting change is opened, the system control unit displays a menu item subjected to setting change last time in the selected state. A table indicating a menu item to be displayed in the selected state is stored in a nonvolatile memory.
Abstract: In a toner containing a resin, a pigment, and a pigment dispersant, the resin contains a polar resin having an acid value of 2.0 to 30.0 mgKOH/g, and the pigment dispersant has the structure represented by the following formula (1) and a polymer moiety bonded thereto.
Abstract: The present invention relates to an information processing apparatus including a power supply part and a voltage compensating circuit. The power supply part is configured to supply electric power to a first electronic device and a second electronic device. The voltage compensating circuit is configured, when the first electronic device is connected to the information processing apparatus, to increase a voltage output from the power supply part and to switch a power supply path for supplying the output voltage to the second electronic device from a first power supply path to a second power supply path including a step-down element so as to decrease the increased output voltage and to supply the decreased output voltage to the second electronic device.
Abstract: A cylindrical shaft of a roller has facing surfaces which form a depression-protrusion-shaped portion of a joint of the cylindrical shaft and which face or make contact with each other and moreover which extend in a direction non-parallel to an axial direction of the cylindrical shaft, and the facing surfaces are inclined at a predetermined engagement angle with respect to a circumferential direction. A generating line of a circumferential surface of a coating layer that coats an outer circumference of the cylindrical shaft and a generating line of a circumferential surface of a photosensitive drum cross each other at a crossing angle smaller than the engagement angle.
Abstract: A search apparatus comprises a determining unit configured to determine a plurality of attributes of an object designated in a first image, and determine a plurality of attributes of an object that is different from the designated object; and a search unit configured to search a second image for the designated object in accordance with a search condition based on the plurality of attributes of the designated object and the plurality of attributes of the object that is different from the designated object.
Abstract: A developer carrying member is disposed below a storage chamber of a frame and has a surface configured such that a plurality of dielectric portions are dispersed on a conductive portion, an upper region of the storage chamber of the frame is enlarged further in a horizontal direction than a lower region in which the developer carrying member is disposed, and the frame has a lower guide surface and includes a curved surface having a tangent plane inclined at a first angle equal to or greater than a degree of an angle of repose of the developer and less than 90 degrees, in an inner wall of the lower region, and an upper guide surface includes a curved surface having a tangent plane inclined at a second angle that is less than the first angle relative to a horizontal plane in an inner wall of the upper region.
March 28, 2017
Date of Patent:
June 12, 2018
CANON KABUSHIKI KAISHA
Kazuhiro Okubo, Jun Miura, Takaaki Shinkawa
Abstract: When an instruction to access a web server of an external device connected via a local interface is acquired from a user, access destination information for accessing the web server via the local interface is acquired. Based on the acquired access destination information, communication is performed with the web server of the external device via the local interface.
Abstract: An image pickup apparatus includes a main mirror holder rotating between a mirror down position in an image pickup optical path and a mirror up position outside the image pickup optical path in accordance with drive of a mirror driving unit, which drives in accordance with rotation of a motor, a sub mirror holder being supported by the main mirror holder to abut against the main mirror holder positioned at the mirror up position, and a driving pin rotating in accordance with the drive of the mirror driving unit and rotating the main and sub mirror holders. The driving pin includes an abutting part that abuts against the mirror driving unit while the mirror driving unit drives. The abutting part is provided with a reduction structure to reduce a bound of the sub mirror holder when the main mirror holder reaches the mirror up position.
Abstract: An element which oscillates or detects terahertz waves includes a resonance unit including a differential negative resistance element, a first conductor, a second conductor, and a dielectric body, a bias circuit configured to supply a bias voltage to the differential negative resistance element, and a line configured to connect the resonance unit and the bias circuit to each other. The differential negative resistance element and the dielectric body are disposed between the first and second conductors. The line is a low impedance line in a frequency fLC of resonance caused by inductance of the line and capacitance of the resonance unit using an absolute value of a differential negative resistance of the differential negative resistance element as a reference.
Abstract: The disclosed structure includes a belt-shaped conveying member configured to convey developer. The conveying member includes a partitioning portion, which is a partition for developer contained in a casing with respect to a conveying direction in which the developer is conveyed, wherein, when the developer container is new, a first developer amount which is an amount of the developer contained at an upstream side that is upstream of the partitioning portion in the conveying direction, is larger than a second developer amount which is an amount of the developer contained at a downstream side that is downstream of the partitioning portion in the conveying direction.
Abstract: A printing apparatus includes a detecting unit, a determination unit, a holding unit, and an instruction unit. The detecting unit detects a sheet type of a sheet used for a print job. The determination unit determines, in a case where a cassette is opened, whether the cassette is used for the print job and the print job is suspended because of a sheet empty state. The holding unit holds, in a case where the determination unit determines that the cassette is used for the print job and the print job is suspended because of the sheet empty state, the sheet type detected by the detecting unit. The instruction unit instructs, in a case where printing is restarted, a printer unit to restart printing of the print job using the sheet type held by the holding unit.
Abstract: Image formation is properly performed by suppressing an influence on a transfer property in the image formation due to variation in a toner particle charge amount. An image forming apparatus comprises a developing device for performing development using developer including a charged toner particle, a toner supply container for supplying the toner particle to a development unit, and a CPU for controlling a toner particle amount supplied to the developing device. The CPU calculates a toner consumption amount consumed by the development. Then, from the result, the CPU calculates a toner supply amount which makes the toner charge amount in the developing device constant. Then, the CPU supplies the toner of the calculated amount to the developing device.
Abstract: An image processing apparatus performs an image recognition process, such as pattern matching or contour detection, on image data supplied from an image pickup device, and stores history data of the image recognition process in an external storage apparatus. In this case, an extraction image is extracted from an extraction region determined in accordance with the image recognition process performed on the input image data and is stored in the external storage device as history data. Furthermore, the history data logged in the external storage device may include a compressed image that is obtained by compressing, using lossy compression, the entire image data subjected to the image processing performed by the image processing apparatus.
Abstract: A power transmission apparatus that wirelessly transmits power includes a detection unit that detects an object, an authentication unit that performs authentication processing including a determination whether the object detected by the detection unit is a power reception apparatus, a power transmission unit that wirelessly transmits power according to a result of the authentication processing performed by the authentication unit, a reception unit that receives a power transmission stop request, and a control unit that stops power transmission according to reception of the power transmission stop request and controls the authentication unit so that the authentication processing is not performed in a period from when the power transmission is stopped to when another object different from the object determined to be a power reception apparatus is detected by the detection unit.
Abstract: An image processing apparatus includes an acquirer which acquires a blurred image, and a generator which acquires a blur estimation area of at least a part of the blurred image to generate an estimated blur based on the blur estimation area, and the generator generates the estimated blur by performing iterative calculation processing that repeats correction processing and estimation processing, the correction processing correcting a blur included in information relating to a signal in the blur estimation area to generate information relating to a correction signal, and the estimation processing estimating a blur based on the information relating to the signal and the information relating to the correction signal, and generates, as the information relating to the correction signal, information relating to a plurality of correction signals by using a plurality of different calculation expressions in at least one correction processing during the iterative calculation processing.
Abstract: An image forming apparatus includes an image bearing member configured to bear a toner image formed using a liquid developer containing toner particles and a carrier liquid, a transfer member, an input portion into which information on a kind of a recording material is inputted, an adjusting device configured to adjust an amount of the carrier liquid of the toner image, and an executing portion configured to execute an operation of the adjusting device depending on the information when the toner image is in the adjusting position. The executing position executes either of a plurality of operations including a first operation in which the amount of the carrier liquid of the toner image is increased, a second operation in which the amount of the carrier liquid is decreased, and a third operation in which the amount of the carrier liquid is not adjusted.
Abstract: The present invention provides an evaluation method of evaluating optical characteristics of a projection optical system by obtaining, by a prediction formula, a predicted value for a fluctuation amount of the optical characteristics relative to an exposure period of a substrate via the projection optical system, the method comprising determining the prediction formula by using a dedicated pattern in which a plurality of marks are arranged in a matrix on an object plane of the projection optical system, wherein the determining includes selecting, from the plurality of marks, at least two marks located in an illuminated region to be formed on the object plane when exposing the substrate, and obtaining the prediction formula based on positions of images of the at least two marks formed on an image plane of the projection optical system.
Abstract: A method and system associated with a camera view of a moving-object in a scene. The method comprises detecting and tracking the moving object over multiple video frames, estimating an orientation of the moving object in each of the video frames, and constructing a cost map from the estimated orientations over the multiple video frames for finding a minimum cost path over the cost map. The Method also comprises determining regularized orientation estimates of the moving-object from the minimum cost path, and locating the vanishing point of the camera view based on an axis of the moving-object from the minimum cost path, the axis formed by using the regularized orientation estimates.
August 30, 2016
Date of Patent:
June 12, 2018
Canon Kabushiki Kaisha
Quang Tuan Pham, Geoffrey Richard Taylor
Abstract: A substrate holder mounting device is provided that is compact and has a simple structure. The substrate holder mounting device according to the present invention is provided with: a first and a second mounting mechanisms (5, 7) that are housed in a chamber and that are respectively configured to be capable of mounting a plurality of substrate holders along a row; row direction drive means that moves the first mounting mechanism to a row direction relatively with respect to the second mounting mechanism; a shifting mechanism (30) that shifts the substrate holders between the first and second mounting mechanisms; and a link-up mechanism that changes positions of the substrate holders in the row direction in the first or second mounting mechanism by a linkage between the shifting mechanism and the above-described row direction drive means.
Abstract: A model containing a plurality of model edges is acquired, and a position that matches the model is searched for within a search image. Within the search image, a plurality of edge extraction regions including the respective plurality of model edges when the model is moved to the position searched for are set, and an arithmetic operation of extracting an edge in each of the plurality of edge extraction regions is performed. If there is an edge extraction region where no edge has been able to be extracted, of the model moved to the position searched for, a model edge located in the edge extraction region where no edge has been able to be extracted is incorporated into an edge set, and fitting is performed to the edge set.
Abstract: An information processing apparatus capable of executing near field wireless communication, comprises: a display unit configured to display a screen; an obtaining unit configured to obtain identification information regarding a device from a near field wireless communication tag with use of the near field wireless communication; a selection unit configured, in a case where the obtaining unit obtained the identification information, to select one of first processing for connecting to the device indicated by the identification information and second processing for connecting to the device indicated by the identification information and sending data to the device, based on a type of screen being displayed by the display unit; and a processing unit configured to execute the processing selected by the selection unit.
Abstract: In order to obtain an observation optical system which has high optical performance while having a wide field of view, and can easily reduce variation of aberration at the time when an eye relief has changed, the present invention provides an observation optical system which is used for an observer to observe an image displayed on an image display surface, and includes in order from an observation side to an image displaying surface side: a first lens having a positive refractive power; a second lens having a negative refractive power; and a third lens having a positive refractive power, wherein a focal length f1 of the first lens, a focal length f2 of the second lens and a focal length f3 of the third lens are each appropriately set so as to satisfy the conditional expression of: 0.40 < f ? ? 1 - f ? ? 2 × f ? ? 3 < 0.80 .