A pixel clock generating device includes a high-frequency clock generator, a comparer, a pixel clock generator, and a value switcher. The high-frequency clock generator is configured to generate a high-frequency clock. The comparer is configured to measure a time interval between a leading-end synchronizing signal and a trailing-end synchronizing signal in a main scanning and calculate an error between the time interval and a target value. The pixel clock generator is configured to generate a pixel clock based on the high-frequency clock and a pixel clock frequency and correct the pixel clock based on the error. The value switcher, including a plurality of groups of values with which the pixel clock is generated, is configured to switch between the plurality of groups of values according to a switching signal after the trailing-end synchronizing signal is inputted, the comparer calculates the error, and the pixel clock generator corrects the pixel clock.

An optical scanning apparatus includes: a casing having a bottom face; a cylindrical portion having a first opening through which a laser beam from a light source passes; a light-transmitting member arranged between the cylindrical portion and a rotary polygon mirror; a plate spring fixing the light-transmitting member; and a sealing member between the cylindrical portion and the plate spring, wherein a width of the first opening narrows progressively in a insertion direction of the plate spring, the sealing member comes into contact with the cylindrical portion in a first region when the plate spring is inserted, and in a second region closer to the bottom face than the first region, a region, in which the sealing member comes into contact with the cylindrical portion, expands toward a center part from two end portions of a leading end portion of the sealing member as the plate spring is inserted further.

A light scanning apparatus satisfies the following conditions: 0.60 (dY.sub.max/d)/(dY.sub.0/d)0.98; and 0.50<Sk/ft<1.00, where, when a deflecting unit rotates at a constant angular velocity, represents a scanning angle between a principal ray of a light flux immediately after deflected by the deflecting unit and an optical axis of an imaging optical system, Y.sub.0 represents an on-axis image height, Y.sub.max represents a first outermost off-axis image height on a side opposite to a light source with respect to the optical axis of the imaging optical system in a main scanning cross section, ft represents a focal distance of the imaging optical system in the main scanning cross section, and Sk represents a distance between a rear-side principal plane of the imaging optical system and a scanned surface on an optical path of a principal ray of the light flux that travels to the on-axis image height.

An image forming apparatus, including: an image signal generating portion configured to generate an image signal based on image data; a light source configured to emit a light beam based on the image signal; and a deflection device configured to deflect the light beam in a main scanning direction, wherein the image signal generating portion includes: a mode setting portion configured to set a plurality of modes including a mode in which a value of a pixel of the image data is not converted and a mode in which the value of the pixel in one or more lines is converted, to a plurality of areas into which a scanning area is divided in the main scanning direction, respectively; and a pixel value conversion portion configured to convert the value of the pixel in each mode in accordance with a position of the pixel in the main scanning direction.

The shifted laser surface texturing method is a method of writing of large arrays of small objects (5) on surface or inside of a material. The whole array of objects (5) is produced by repeated linear raster (1) laser processing with sequential shifting of linear raster between each repetition of the scanning process. The linear raster is a set of paths (1) for laser beam scanning. Distance between spots (2) in the laser beam path (1) of the linear raster is defined by speed of laser beam scanning and by period between laser pulses. Sequence of linear raster shifts (4) defines the form of the small objects (5) in the array. Computational data for an array of the same objects (5) is very low. It is comparable to the number of lines N in one linear raster plus number of spots in one object. The presented method eliminates heat accumulation effect and strongly decreases plasma shielding effect, while at the same time enables effective use of high average power pulsed lasers.

A light scanning apparatus, including: a light source; a rotary polygon mirror configured to deflect a light beam emitted from the light source; a plurality of optical members configured to guide the light beam, which is deflected by the rotary polygon mirror, to a photosensitive member; a drive motor configured to rotate the rotary polygon mirror; an optical box to which the light source is attached, the optical box containing the rotary polygon mirror, the drive motor, and the optical members; and a dynamic vibration absorber mounted inside the optical box and configured to be vibrated by vibrations of the optical box, wherein the plurality of optical members are supported on a bottom portion of the optical box, and the dynamic vibration absorber is disposed on the bottom portion of the optical box at a position between at least two adjacent optical members among the plurality of optical members.

An incidence angle of laser light with respect to a photosensitive member in a main-scanning direction is different depending on an exposure position. Hence, the spot shape of the laser light on the photosensitive member is different in the main-scanning direction. A filter coefficient is changed in the main-scanning direction, and image data is corrected with the filter coefficient.

To restrict an angle change of a reflection surface of a reflection member that reflects a scanning light beam, an optical scanning device includes a first support portion that supports a reflection mirror at one point at an end in a longitudinal direction of the reflection mirror, a second support portion that supports the reflection mirror at a plurality of points at the other end, a reinforcement portion that reinforces a structure of the second support portion side of a housing in the longitudinal direction of the reflection mirror, compared to a structure of the first support portion side of the housing, one first fixing portion that is used to fix the housing to an image forming apparatus on the first support portion side, and a plurality of second fixing portions that are used to fix the housing to the image forming apparatus on the second support portion side.

A method for making laser engravings on a web of paper, including prearranging a paper web conveying device; defining a working area along a path of the web; prearranging an emitter of laser pulses; prearranging a movable pointing device, selecting an engraving pattern to be engraved on the web; calculating an instruction file containing pointing instructions; selecting an emission power of the emitter of laser pulses; emitting laser pulses through the emission power; and operating the movable pointing device according to the instruction file.

A light source includes a light emitting element, and an optical system that directs light output from the light emitting element to a surface of a photosensitive member. An irradiation amount of light for forming a second electrostatic latent image is larger than an irradiation amount of light for forming a first electrostatic latent image. A position at which a propagation efficiency of light peaks in a scanning direction of the light is located between a center of an image height of the optical system and a surface area in which the second electrostatic latent image is formed out of the surface of the photosensitive member.