In an image-forming apparatus, an optical scanning device that is adjustable in a turn available manner around a turn axis line parallel to an axis line orthogonal to a main scanning direction of a light beam is attached to an image-forming apparatus body. The image-forming apparatus body has a shaft support that supports the optical scanning device in a turn available manner around a turn axis line and a holder facing a housing at a position different from that of the shaft support. The optical scanning device is held by the image-forming apparatus body in a state in which an elastic member is sandwiched between the housing and the holder in a pressed manner.

Disclosed is an optical deflector which includes: a polygonal mirror, a drive motor, a cover member, and a temperature detection unit. The cover member includes: a first cover portion defining a first space in which the polygonal mirror is installed, wherein the first cover portion is formed with a first opening opened in opposed relation to an outer peripheral surface of the polygonal mirror; a second cover portion defining a second space which is communicated with the first space and in which the drive motor is installed, wherein the second cover portion is formed with a second opening opened in opposed relation to a motor body of the drive motor; and a third cover portion defining a third space which is communicated with the second space. The temperature detection unit is mounted to the third cover portion so as to close the third space.

Disclosed is an optical deflector including a polygonal mirror and a drive motor each mounted on a substrate, a cover member covering the polygonal mirror and the drive motor, and an electronic component. The cover member includes: a first cover portion defining a first space in which the polygonal mirror is installed, wherein the first cover portion is formed with a first opening opened in opposed relation to an outer peripheral surface of the polygonal mirror; and a second cover portion defining a second space which is communicated with the first space and in which the drive motor is installed, wherein the second cover portion is formed with a second opening opened in opposed relation to a motor body of the drive motor. When viewed in the first direction, the electronic component is disposed such that it falls within an open region of the second opening.

A method of reducing jitter error in a laser scanning system adapted to produce a scanned image including a number of lines of an object. The method includes the steps of providing a reference object arranged such that the scanned image produced by the laser scanning system includes a reference image of the reference object, processing the reference image to calculate an error arising from non-repeatable displacement of the lines of the reference image, and adjusting at least one operating parameter of the laser scanning system in response to the calculated error.

A laser scanning unit includes a first light source, a second light source, a scanning portion, a light detection portion, a timing control portion, and a light source control portion. The scanning portion is configured to cause light emitted from the first light source and the second light source to be scanned. The light detection portion is configured to detect the light that is scanned by the scanning portion. The timing control portion is configured to control a timing of writing an electrostatic latent image according to a timing of light detection by the light detection portion. The light source control portion is configured to: cause the light detected by the light detection portion to be emitted from the first light source in the first mode; and cause the light detected by the light detection portion to be emitted from the second light source in the second mode.

The present application discloses methods and systems for calibrating a scanning system. In one embodiment, the calibration method determines a dark level of at least one pixel, determines a maximum white level for at least one pixel and adjusts the current of an illumination source based upon an output of an analog to digital converter. In another embodiment, the scanning system has a circuit for dynamically adjusting the output of an illumination source. The circuit has a pulse width modulated signal generator for generating a pulse width modulated signal and a driver for receiving the pulse width modulated signal and causing current to the illumination source to be modulated based on the pulse width modulated signal.

A method and system are disclosed for using circular symmetry to eliminate the angle limitations of an optical axis in a scanned aperture holography system. A Room-sized Holography System may be a scanned aperture holographic video display and may comprise a rotating platform, a telescope comprising a first lens and a second lens, and scanners at the Fourier plane where the focal length of the first lens and the second lens meet. The platform may rotate around an axis aligned with a spatial light modulator. When the platform rotates, the scanners rotate, thereby de-rotating a SAW image. The second lens may be a spherical reflective surface for redirecting light from the spatial light modulator, having passed through the first lens and reflected off a mirror-scanner, toward a user's eyes. The user may be on a chair above the spatial light modulator, wherein the chair is configured to rotate with the spatial light modulator.

Systems and techniques for scanning-beam display are provided to use local dimming on the optical energy of at least one optical beam to minimize the non-uniform image brightness across the screen. This local dimming during the beam scanning can be achieved by adjusting optical energy of at least one optical beam during the scanning based on (1) the location of the scanning optical beam and (2) the predetermined distortion information at the location.

A light scanning apparatus, including: a light source configured to emit a light beam; and a rotary polygon mirror configured to deflect the light beam emitted from the light source so that the light beam scans a surface of a photosensitive member, wherein the rotary polygon mirror is formed in a four-sided polygon, and wherein a difference between a pair of diametrically opposed interior angles of the rotary polygon mirror is larger than 0.03°, and a difference between another pair of diametrically opposed interior angles of the rotary polygon mirror is 0.03° or less.

An image forming apparatus includes a rotating polygon mirror, a motor, a bearing portion, a measurement processing portion, and a determination processing portion. The rotating polygon mirror causes a light beam emitted from the light source to be scanned. The motor rotates the rotating polygon mirror. The bearing portion rotatably supports a rotation shaft of the motor via a lubricant. The measurement processing portion measures a transition time that is a time required for the motor to transition from a stationary state to a driving state in which the motor rotates at a predetermined speed. The determination processing portion determines whether or not a maintenance is required, based on the transition time measured by the measurement processing portion.