Abstract: A method for transferring objects includes providing a medium in a reservoir, the medium containing objects; providing a substrate having an acceptor surface, the acceptor surface facing an opening of the reservoir; determining a first target focus point in the medium; and generating a first laser pulse or first laser pulse train focused onto the first target focus point. Pulse intensity of the first laser pulse or pulse train at the first target focus point and/or pulse duration of the first laser pulse or pulse train is/are chosen to generate a droplet of the medium ejected towards the acceptor surface. A center wavelength of the first laser pulse or pulse train is larger than 500 nm, larger than 650 nm, or between 0.9 ?m and 1.35 ?m. The first target focus point is determined relative to the position of at least one object of the objects.

Abstract: A light-emitting device includes: a first light-emitting unit that extends in one direction and that has a first emission surface that emits light located along the one direction; a second light-emitting unit that is located in the one direction with respect to the first light-emitting unit, that extends in the one direction, and that has a second emission surface that emits light located along the one direction; a cleaning unit that is capable of moving in the one direction and an opposite direction that is opposite to the one direction to clean the first emission surface; a transmission part that extends from the cleaning unit in the one direction and that transmits a moving force for moving the cleaning unit to the cleaning unit; and an extending part that extends from the transmission part in the one direction to elongate the transmission part.

Abstract: Systems and methods for manipulation of the polarization state of light emitted by a laser projector to reduce the angle range of a scanning mirror articulated by a micro-electromechanical system MEMS to reduce power consumption are disclosed. A system includes a light source configured to emit laser light, a scanning mirror, and an angle expander disposed between the light source and the scanning mirror, the angle expander being configured to cause the laser light from the light source to be reflected at least once from the angle expander and at least twice from the scanning mirror.

Abstract: Systems and methods for medication fillings management are disclosed. For example, user information and/or refill schedules associated with users may be utilized to predict which users are likely to miss a medication refill. The presently disclosed systems and methods may determine health indicators associated with users and, by utilizing one or more machine learning techniques, determine which health indicators, alone or in combination, are associated with users prone to missing refills. As such, the system may predict users that are likely to miss a refill and may generate preemptive, targeted refill reminders in order to prevent the missed refill before it occurs.

Abstract: A holding member includes a first side wall portion and a second side wall portion, and a part of a surface of a substrate on a side opposite from a mounting surface and a holding member are fixed to each other by an adhesive. In the first side wall portion, an inserting hole is disposed opposing a corner portion as of the substrate in a widthwise direction of the substrate and also, in the second side wall portion, another inserting hole is disposed opposing another corner portion of the substrate.

Abstract: An image forming apparatus is operable in a first mode in which a photosensitive drum is rotated at a first rotational speed and a second mode in which the photosensitive drum is rotated at a second rotational speed slower than the first rotational speed. In this image forming apparatus, the light-emitting portions are controlled such that the number of light-emitting rows for multiply exposing regions, each of which corresponds to one pixel on the photosensitive drum in the first mode, is greater than that in the second mode.

Abstract: Provided is a light scanning apparatus including a deflector deflecting a light flux to scan a scanned surface, and an imaging optical element including an optical surface and guiding light flux from deflector to scanned surface. The light scanning apparatus causes a first marginal ray on a side closer to a first deflection point on deflector in a first cross section including first deflection point and being perpendicular to a main scanning section and a sub-scanning section, the first marginal ray being included in an on-axis light flux reflected by the optical surface after being deflected at first deflection point, to travel toward a position spaced apart from first deflection point in a sub-scanning direction by 4 mm or more in first cross section. A sub-scanning width of on-axis light flux on first cross section is smaller than a sub-scanning width of on-axis light flux on optical surface.

Abstract: An image forming apparatus includes a controller. The controller is configured to switch between (i) first speed printing in which a rotation speed of the polygon mirror is a first speed and the power of a laser beam from a first and second laser light sources is a first laser power, and (ii) second speed printing in which the speed of the mirror is slower than the first speed and the power of laser beam from the light sources is a second power weaker than the first power. The controller is configured to control an output timing of the laser beam from the light sources in the second speed printing based on the timings at which the laser beam is detected by first photodetector and second photodetectors when the laser powers of the first laser light source and the second laser light source are changed, respectively.

Abstract: A method includes transferring multiple discrete components from a first substrate to a second substrate, including illuminating multiple regions on a top surface of a dynamic release layer, the dynamic release layer adhering the multiple discrete components to the first substrate, each of the irradiated regions being aligned with a corresponding one of the discrete components. The illuminating induces a plastic deformation in each of the irradiated regions of the dynamic release layer. The plastic deformation causes at least some of the discrete components to be concurrently released from the first substrate.

Abstract: Multi-polygon, vertically-separated laser scanning apparatus and methods are disclosed. An example apparatus includes a multi-polygon. The multi-polygon includes a first polygon, a central axis, and a second polygon. The first polygon includes a first plurality of outwardly-facing mirrored facets. The second polygon includes a second plurality of outwardly-facing mirrored facets angularly offset about the central axis relative to the first plurality of outwardly-facing mirrored facets. The second polygon is positioned relative to the first polygon along the central axis. The first and second polygons are rotatable about the central axis.

Abstract: Methods for manufacturing a display device are provided. The methods include providing a plurality of light-emitting units and a substrate. The methods also include transferring the light-emitting units to a transfer head. The methods further include attaching at least one of the plurality of light-emitting units on the transfer head to the substrate by a bonding process, wherein the transfer head and the substrate satisfy the following equation during the bonding process: Q?|?T1T2A(T)dT??T1T3E(T)dT|<0.01, wherein A(T) is the coefficient of thermal expansion of the transfer head, E(T) is the coefficient of thermal expansion of the substrate, T1 is room temperature, T2 is the temperature of the transfer head, and T3 is the temperature of the substrate.

Abstract: A printer includes a spindle that rotates a fibrous object opposite a plurality of printheads while a forced air heater directs heated air toward the surface of the fibrous object. The plurality of printheads eject drops of solid ink onto the surface of the fibrous object to form a solid ink image on the fibrous object and the heated air affixes the solid ink image to the surface of the fibrous object without requiring pressure to affix the solid ink image to the fibrous object.

Abstract: A device may include a multispectral filter array disposed on the substrate. The multi spectral filter array may include a first metal mirror disposed on the substrate. The multi spectral filter may include a spacer disposed on the first metal mirror. The spacer may include a set of layers. The spacer may include a second metal mirror disposed on the spacer. The second metal mirror may be aligned with two or more sensor elements of a set of sensor elements.

Abstract: The device and method according to the invention are used to transfer an electronic ferromagnetic component from a carrier to a substrate using a magnetic assembly. The magnetic assembly is designed and arranged to aid in the correct positioning of the at least partly ferromagnetic electronic component on the substrate. The magnetic field generated by the magnetic assembly produces a magnetic force oriented from the carrier towards the substrate, said magnetic force aiding the transfer of the component from the carrier to the substrate such that a significantly increased positioning accuracy of the component is achieved compared to a transfer without said magnetic force.

Abstract: A laser processing method comprises generating a laser beam comprising laser pulses having a duration less than 1000 ps, focussing the laser beam to form a focal region inside a transparent material and varying the position of at least one of the focal region and the transparent material so as to provide a pulse-to-pulse overlap of between 45% and 99%, thereby to form a smooth material modification inside the transparent material.

Abstract: A display device, to provide compensation for change in color level due to different viewing directions of a display surface and compensation for other optical characteristics of the display surface in a compatible manner, includes a light-emitting element layer including a light-emitting layer including a light-emitting element, a first electrode disposed below the light-emitting layer, and a second electrode disposed above the light-emitting layer, wherein an optical compensation layer is disposed above the light-emitting element layer, the optical compensation layer being configured to compensate for prevention of external light reflection on a display surface and compensate for change in color level of the display surface due to different viewing directions of the display surface.

Abstract: An image forming apparatus includes an apparatus body, an image forming unit, a covering member, and a light emitting unit. The apparatus body has an opening through which an internal space is exposed. The image forming unit includes an image carrier to form an image on a sheet. The covering member has a closing face capable of closing the opening of the apparatus body from above. The covering member is pivotally supported on the apparatus body to pivot between a close position where the closing face closes the internal space and an open position where a portion of the image forming unit is exposed to the outside. The light emitting unit is attached to the closing face, and emits a light to the circumferential surface of the image carrier to form the electrostatic latent image in a state where the covering member is at the close position.

Abstract: The invention provides a substrate treatment method and apparatus. Embodiments show a substrate in the form of a rotary encoder ring having a pattern of marks producable by means of a laser treatment device controllable to produce the pattern in the correct manner while there is continuous relative displacement between the ring and the laser treatment device.

Abstract: An image forming apparatus includes a main assembly and a drawer unit. The drawer unit includes a rotatable photosensitive member, an optical print head including a light emitting element, a substrate, an electroconductive member, and a first grounding member. The accommodating portion includes a second grounding member configured to ground the electroconductive member in contact with the first grounding member when the drawer unit is positioned between an accommodated position and a drawn-out position.

Abstract: An arrangement is therefore employed in which a flexible flat cable is guided by a guide member situated at a position facing a metal rear plate and the flexible flat cable extending from a connector to the metal rear plate is brought into contact with a wall portion of the metal rear plate so that the flexible flat cable is grounded.

Abstract: An image forming apparatus that includes a cover. By rotation of the cover from a closed position toward an open position, a pressing portion urges a portion-to-be-urged, and a slidable portion is slid (moved) from one end side toward the other end side with respect to a rotational axis direction of a photosensitive drum by the urging, so that an optical print head moves from an exposure position toward a retracted position.

Abstract: A backlight assembly includes an optical plate, a light source provided near the optical plate, and a brightness redistribution film provided above the optical plate. When light emitted from the light source passes through the optical plate and the brightness redistribution film, a front view angle brightness measured in a normal direction of a light exiting surface of the brightness redistribution film relative to a maximum brightness emitted from the backlight assembly has a brightness ratio N, wherein the brightness ratio N is greater than or equal to 60% and is smaller than 100% (60%?N<100%).

Abstract: A displaying apparatus including: a panel substrate; a plurality of light emitting devices arranged on the panel substrate; and at least one connection tip disposed on one surface of each of the light emitting devices. Each of the light emitting devices includes a light emitting structure including a first conductivity type semiconductor layer, a second conductivity type semiconductor layer, and an active layer interposed between the first and second conductivity type semiconductor layers; and first and second electrode pads disposed on the light emitting structure.

Abstract: An imageable material can be used to form a mask element that in turn is useful for providing relief images such as in flexographic printing plates. The imageable material has, in order: (a) a transparent polymeric carrier sheet; (b) a non-ablatable light-to-heat converting having an average dry thickness of 1-5 ?m and comprising: (i) an infrared radiation absorbing material at 0.1-5 weight %; (ii) a thermally crosslinked organic polymeric binder material; and (iii) non-thermally ablatable particles having an average particle size of 0.1-20 ?m in an amount of 0.2-10 weight %; and (c) a non-silver halide thermally-ablatable imaging layer (IL) disposed on the LTHC layer, the IL comprising a second infrared radiation absorbing material and a UV-light absorbing material dispersed within one or more thermally-ablatable polymeric binder materials.

Abstract: A spectral color measuring apparatus includes a light source, an optical emitting element configured to regulate a position of the light source in an emission direction of a light flux, and to guide the light flux emitted from the light source onto a color-patch image formed on a surface of a sheet, and an urging member configured to urge the light source toward the optical emitting element in the emission direction of the light flux. With this, relative positional accuracy between the light source and the optical emitting member is enhanced, thereby enabling accurate measurement of a color of an image in a short color measuring takt (time period).

Abstract: A technical object of the present invention is to devise a glass substrate that is suitable for supporting a substrate to be processed to be subjected to high-density wiring and enables correct recognition of production information and the like, and a laminate using the glass substrate. In order to achieve the technical object, the glass substrate of the present invention has a total thickness variation of less than 2.0 ?m and includes an information identification part formed of a plurality of dots.

Abstract: In a method of inspecting liquid chemicals discharged from an ink jet head according to example embodiments, at least two laser beams may be irradiated onto the liquid chemicals discharged from the ink jet head, and the conditions of the liquid chemicals may be identified by detecting an interference pattern obtained from a laser scattering generated by passing the liquid chemicals through the at least two laser beams.

Abstract: An image forming apparatus includes a rotatable photosensitive drum, an optical print head that exposes the photosensitive drum and is insertable and removable through a front side of the apparatus body by an operator, a front plate that forms a part of a housing of the apparatus body and that includes an opening through which the optical print head passes when inserted and removed, a cable having one end connected to the optical print head and running along the optical print head toward the front side of the apparatus body when the optical print head is mounted to the apparatus body, and a connector which is arranged so as to have at least a part located on an outer side of the opening and to which another end of the cable is connected to be detachably attachable in order to transmit a drive signal to the optical print head.

Abstract: An image forming apparatus includes circuitry, a reader, and an exposure device that drives lighting elements aligned in a main scanning direction to form a first test image. The circuitry acquires density of first sub-areas, into which the first test image is divided in the main scanning direction, and calculates first correction data based on density of each of the first sub-areas and average density of the first sub-areas, to correct light amounts of the lighting elements. The exposure device forms a second test image with the light amounts corrected. The circuitry acquires density of second sub-areas, into which the second test image is divided in the main scanning direction, and calculates second correction data based on density of a second sub-area adjacent to each of the second sub-areas, to further correct the light amounts. The second sub-areas are differently located from the first sub-areas in the main scanning direction.

Abstract: Compact hybrid developing machine that exposes a photosensitive substrate (1) using an LED or LCD display (2,3) wherein the substrate (1) is placed in direct contact with the image generating layer (colour generating layer+channelling layer) of the display (2,3). When the display is of LCD technology, the filters (21) of the colour generating layer are placed closer to the substrate (1) than the liquid crystal layer (22). In both types of display (2,3), a channelling layer is installed within the image generating layer, for example, a black matrix (4) of opaque elements. When using an LCD display (2), this may have a unifying filter (24) or a black translucent filter (25) before the light diffusing layer.

Abstract: An optical scanning device has a housing body and an upper lid. The upper lid is formed at the end part thereof with a plurality of engagement holes, the housing body is provided at the sidewall thereof with a plurality of upper lid engaging projecting parts that project outward from a housing and are engaged with the engagement holes, an input gear is held to an end part of one side or the other side of the upper lid in a predetermined direction, and the plurality of upper lid engaging projecting parts are formed such that amounts of projecting outward from the housing are increased as the plurality of upper lid engaging projecting parts are positioned at a side near the input gear in the predetermined direction.

Abstract: Surface identification processing is performed using a period of a BD signal when an amount of light incident on a BD sensor reaches an amount equal to or more than a threshold value, and the surface identification processing is not performed using the period of the BD signal in a state where the amount of light incident on the BD sensor is less than the threshold value. Thus, malfunction of the image forming apparatus due to failure of the surface identification processing is suppressed.

Abstract: An alignment method and an alignment system are provided. The alignment method includes: providing a wafer including an exposed surface, wherein an alignment mark and a reference point with a reference distance are provided on the exposed surface; placing the wafer on a reference plane; performing an alignment measurement on the exposed surface to obtain a projection distance, configured as a measurement distance, between the alignment mark and the reference point on the reference plane; performing a levelling measurement between the exposed surface and the reference plane to obtain levelling data of the exposed surface; obtaining a distance, configured as an expansion reference value, between the alignment mark and the reference point in the exposed surface; obtaining an expansion compensation value based on a difference between the expansion reference value and the reference distance; and adjusting parameters of a photolithography process based on the expansion compensation value for an alignment.

Abstract: An example laser assembly for a laser printer may include a plurality of lasers to emit respective photons; a prism to redirect the respective laser beams emitted from the plurality of lasers toward a collimator lens of the laser printer to generate a photon beam; and one or more processors to: determine a timing schedule for individually activating the plurality of lasers based on a resolution setting of the laser printer, and when printing at a resolution corresponding to the resolution setting, control activation of each of the plurality of lasers to emit the respective photons according to the timing schedule to form the photon beam.

Abstract: An adjustment method of an optical scanning device, in which an uppermost position at an incident surface of the image forming lens, through which a light beam being deflected and scanned passes, and a lowermost position at the incident surface of the image forming lens, through which a light beam being deflected and scanned passes, are detected in a height direction perpendicular to the main scanning direction in an effective range corresponding to a latent image formation target range on the scanning target surface, and a center height between the uppermost position and the lowermost position is allowed to approximately coincide with a height of a bus line of the image forming lens at the incident surface of the image forming lens.

Abstract: An image forming apparatus comprising: an exposing unit including: a first light source comprising a first light emitter and a first light receiver including a first electric output responsive to a received light quantity of the first light emitter; a second light source comprising a second light emitter and a second light receiver including a second electric output responsive to a received light quantity of the second light emitter; and a first light-source driver electrically connected to the first light source and the second light source. The first light-source driver includes: a first output terminal electrically connected to the first light emitter; a second output terminal electrically connected to the second light emitter; and an input terminal electrically connected to both the first electric output and the second electric output.

Abstract: An exposure unit includes first and second exposure heads. The first exposure head includes: first light emitting devices each emitting a first light beam; a first optical system performing imaging of each of the first light beams; a first coupler; and a first base member. The first coupler is provided at a first position, in the first base member, based on a position at which the imaging performed by the first optical system is performed. The second exposure head includes: second light emitting devices each emitting a second light beam; a second optical system performing imaging of each of the second light beams; a second coupler; and a second base member. The second coupler is provided at a second position, in the second base member, based on a position at which the imaging performed by the second optical system is performed and is fit into the first coupler.

Abstract: A light-beam-scanning apparatus includes first and second array-light sources including plural light-emitting units and a light-receiving unit; first and second light-source-control units for controlling light emission of the light-emitting units; a write-control unit for controlling the light-source-control units; a deflection unit for deflecting a direction of light emitted from the light-emitting units; and a synchronization-detection element for generating a synchronization-detection signal according to the light deflected by the deflection unit incident onto the synchronization-detection element. Initialization of the light-emitting units of the second array-light source is performed after initialization of the first array-light source is performed; and when the initialization of the light-emitting units of the first array-light source is being performed, a signal for causing the light-emitting units of the second array-light source not to emit light is input to the second light-source-control unit.

Abstract: An image forming apparatus has a light scanning apparatus which is capable of aligning a lens with a plurality of light-emitting devices and forming a high-quality image while suppressing generation of moiré. In a first image formation mode, light-emitting devices outputting light beams exposing both ends of the photosensitive member in a rotational direction and at least a part of light-emitting devices exposing an area between exposure positions of the light-emitting devices outputting the light beams exposing the both ends are used to form an electrostatic latent image on the photosensitive member. In a second image formation mode, the light-emitting devices outputting the light beams exposing both ends are not used, and at least a part of light-emitting devices exposing an area between exposure positions of the light-emitting devices outputting the light beams exposing both ends are used to form the electrostatic latent image on the photosensitive member.

Abstract: An image forming apparatus including: a light irradiating unit configured to irradiate a photosensitive member charged by a charging unit with light to form an electrostatic latent image; a processing unit configured to generate M-bit (M is an integer not less than 2) density data indicating a density based on the input image data, to generate (M+N)-bit processing data based on the M-bit density data and N-bit (N is an integer not less than 1) correction data, to convert the processing data into a plural-bit binary drive data corresponding to a value of the processing data, and to serially output the plural-bit drive data bit by bit to generate a drive signal; and a drive unit configured to drive the light irradiating unit based on the drive signal.

Abstract: Methods for ultrashort pulse laser processing of optically transparent materials. A method for scribing transparent materials uses ultrashort laser pulses to create multiple scribe features with a single pass of the laser beam across the material, with at least one of the scribe features being formed below the surface of the material. This enables clean breaking of transparent materials at a higher speed than conventional techniques. Slightly modifying the ultrashort pulse laser processing conditions produces sub-surface marks. When properly arranged, these marks are clearly visible with side-illumination and not clearly visible without side-illumination. In addition, a method for welding transparent materials uses ultrashort laser pulses to create a bond through localized heating. The ultrashort pulse duration causes nonlinear absorption of the laser radiation, and the high repetition rate of the laser causes pulse-to-pulse accumulation of heat within the materials.

Abstract: An LED scanning array driver chip and a regulation method capable of self-regulating brightness linear change are provided. The LED scanning array driver chip is provided with LED current non-linear automatic control circuits to automatically regulate the average current of LEDs for the brightness of the LEDs to become bright or dark linearly, enabling each LED of the LED array to control the current non-linear change individually. This greatly reduces the time resource for a MCU to write registers inside the driver chip.

Abstract: An optical system including a laser apparatus, a spatial light modulator to receive a laser beam, an optical-conditioning system to capture a propagating diffracted beam of the optical pattern and to form at least one of a magnified version and a demagnified version of the optical pattern and to control a quality of the optical pattern, a uniformity maintaining optical amplifier to receive the laser beam output from the spatial light modulator and generate an amplified laser beam such that a final optical pattern is an amplified version of the optical pattern as generated by the spatial light modulator, the amplified laser beam having a substantially uniform amplification across the cross-section of the beam, and at least one of a time-bandwidth pulse duration control mechanism including at least one of a pulse stretching element and pulse compression element, and a frequency conversion device.

Abstract: An optical scanning system includes a variable-focus element, an imaging lens and a deflector, wherein the reciprocal of the focal length f of the variable-focus element is changed from 1/fMIN to 1/fMAX, and for the case that the equation 1/f={(1/fMAX)+(1/fMIN)}/2 holds, a beam which has passed through the variable-focus element is a divergent beam, and x 2 + x 2 2 x 1 > x 3 ( 1 ) is satisfied, where x1 represents a distance from a virtual image point of the divergent beam to the principal point on the entry side of the variable-focus element, x2 represents a distance from the principal point on the exit side of the variable-focus element to the principal point on the entry side of the imaging lens, and x3 represents a distance from the principal point on the exit side of the imaging lens to an image point.

Abstract: A light-emitting element array module, image forming apparatus and method are provided. The light-emitting element array module includes a control driver configured to receive print data and operate according to the received print data, and light-emitting element array chips configured to receive a signal from the control driver and operate according to the received signal, wherein the control driver applies a start signal to a transfer element array by using a signal applied to a light-emitting element array of the light-emitting element array chips.

Abstract: A printhead for a device capable of printing, including: a frame; a light-emitting diode (LED) assembly including a housing engaged with the frame, a plurality of LEDs one the housing and extending in a first transverse direction, and at least one lens parallel to the plurality of LEDs in the first traverse direction and arranged to focus light from the LEDs; and a displacement assembly connected to the frame and engaged with the LED assembly and arranged to displace the LED assembly, with respect to the frame to a first position for an operating mode for the printhead, in which light from the plurality of LEDs illuminates media passing through the printbar in first or second process directions orthogonal to the first transverse direction and to a second position for a cleaning mode for the printhead, in which a cleaning operation for the at least one lens is enabled.

Abstract: The present invention is directed to a device and a laser, eye-safe method for laser marking slides for use in conjunction with a light microscope. The device is an attachment for a light microscope that allows the operator to make marks on preparations of biological tissues or other materials placed on a glass slide or between a glass slide and a cover slip. The marks can be used to indicate or highlight a microscopic structure or feature of interest. The marking on the slide is performed as the specimen is examined, without having to remove it from the microscope stage. In this way the invention has application in a biomedical or pathology laboratory for diagnostic, research, archival, and teaching or training purposes.

Abstract: Provided is a method for marking on a pressed metallic component whose visibility and corrosion resistance in a marking target is ensured. The method includes a step of irradiating a base treatment target region including a marking target region with a laser beam on a first irradiation condition, and a step of irradiating the marking target region with the laser beam on a second irradiation condition, in which a charged energy of the laser beam is set to be smaller on the first irradiation condition than the second irradiation condition, thereby providing between the marking pattern and a non-irradiation region, a base region having a residual stress greater than that of the non-irradiation region and a residual stress smaller than that of the marking pattern, so as to ensure a visibility. Furthermore, a corrosion resistance is ensured by using a metallic member which is heat-treated to enhance the hardness.

Abstract: An image processing apparatus has: an obtaining unit configured to obtain first information used to correct a deviation in an image in a sub scanning direction due to a curve of a scanning line of a first beam and second information used to correct a deviation in an image in the sub scanning direction due to a curve of a scanning line of a second beam; a setting unit configured to set a common position in a main scanning direction to image data of a single color plane for each of the first beam and the second beam based on the obtained first and second information; and a correcting unit configured to shift pixels included in the image data of the single color plane for each of the first beam and the second beam in the sub scanning direction at the set common position.

Abstract: An image forming apparatus determines a time length of a non-image-forming period in which image formation is not performed, the non-image-forming period being from when image formation on one recording sheet ends to when image formation on the next recording sheet starts, and based on the determined time length, decides the number of times of executing measurement (BD interval measurement) of a generation timing difference between detection signals corresponding to light beams emitted from two light emitting elements. The image forming apparatus executes the decided number of times of BD interval measurement and calculates an average value of the resultant measurement values.