This disclosure provides methods and systems that adaptively adjust the gain of the drive signal to a slow-scan mirror to compensate and stabilize the mirror to achieve desired performance metrics. Non-ideal characteristics of the slow-scan mirror, including the mirror and related assembly, exhibit behaviors that impact the overall gain of the device, which changes over time and operating environment. To compensate for these non-ideal characteristics, the drive signal to the slow-scan mirror may need to be adjusted to achieve the desired beam deflection angle. An adaptive inner loop gain control structure may be employed to dynamically adjust the gain of the inner-control loop to achieve a target gain such that the overall gain variations from the slow scan mirror and other components are scan mirror such that compensated and stabilized. The parameters, logic and blocks of the inner loop gain control may be implemented in hardware, software, or combinations thereof.

Examples are disclosed herein related to controlling a scanning mirror system. One example provides a display device, comprising a light source, a scanning mirror system configured to scan light from the light source in a first direction at a first, higher scan rate, and in a second direction at a second, lower scan rate, and a drive circuit configured to control the scanning mirror system to display video image data by providing a control signal to the scanning mirror system to control scanning in the second direction, and for each video image data frame of at least a subset of video image data frames, combining the control signal with an adjustment signal to adjust the scanning in the second direction, the adjustment signal comprising a low pass filtered signal with a cutoff frequency based on a lowest resonant frequency of the scanning mirror system in the second direction.

A light scanning unit includes a plurality of light source portions to emit modulated light beams intermittently according to image information of an image forming job while the image forming job is performed, and a plurality of polygonal mirrors, having different numbers of deflection facets, to rotate at a same rotational speed while is image forming job is performed so that the modulated light beams are incident on a subset including at least one of the deflection facets of the plurality of polygonal mirrors that rotate and the subset including the at least one of the deflection facets deflects the modulated light beams incident thereon to scan an object to be exposed.

An optical scanning device includes a light source, a deflector, a random number generator, a selection part, a random number assignment part and an exposure control part. The light source includes a plurality of light emitting parts arranged in a predetermined direction at fixed intervals in a sub-scanning direction. The random number assignment part is configured to assign a random number sequence to each light emitting part constituting a set of target light emitting parts as an index for specifying a timing at which a light emitting time of the set of target light emitting parts is set to a correction value different from a reference value and to update the assignment of the random number sequence at a random number update period. The random number update period coincides with a scanning period of each light emitting part constituting the set of target light emitting parts.

Mirror control circuitry operates to control a movable mirror. The mirror control circuitry includes drive circuitry for providing a drive signal to the movable mirror, and a processor. The processor causes the drive circuitry to generate the drive signal so as to have pulses with leading edges occurring an offset period of time after a maximum opening angle of the movable mirror and trailing edges occurring an offset period of time before a zero crossing of the movable mirror. The processor may sample a mirror sense signal from the movable mirror at times at which a derivative of capacitance of the movable mirror with respect to time is zero, and then perform an action based upon the samples.

The detector that detects a light beam emitted from a light source of a second image forming device and reflected by a polygon mirror, and an adjustment device that performs adjustment processing of adjusting the velocity of the polygon mirror based on an output of the detector are provided. Before a first image forming device performs the image forming processing, the adjustment device performs the adjustment processing while causing the light source of the second image forming device to emit the light beam during a time period including at least a time period in which a photosensitive member of the second image forming device is emitted with the light beam. Before the adjustment processing is finished, the first image forming device starts to move a developing member to a developing position.

In one embodiment, a lidar system includes a light source configured to emit a first set of optical signals that include a first optical signal. The lidar system also includes a scanner that includes a polygon mirror configured to: rotate around an axis of rotation at a rotation rate, and direct the first set of emitted optical signals into a field of regard of the lidar system with the polygon mirror rotating at a first rotation rate. The lidar system further includes a receiver configured to detect a first received optical signal that includes a portion of the first optical signal that is scattered by a target located a distance from the lidar system. The lidar system also includes a controller configured to adjust the rotation rate of the polygon mirror for a second set of optical signals emitted by the light source.

An image forming apparatus including: a drive motor configured to rotate a rotary polygon mirror to deflect light beam; a signal generation unit configured to generate a rotation synchronous signal; and a rotation control unit configured to control a rotation speed of the rotary polygon mirror, wherein the rotation control unit executes a disabling processing of disabling control of the drive motor based on the rotation synchronous signal, wherein a term of a first disabling processing for a first rotation speed is shorter than a term of a second disabling processing for the second rotation speed, and wherein when the rotation speed of the rotary polygon mirror is changed from the first rotation speed to the second rotation speed, the rotation control unit switches the disabling processing from the first disabling processing to the second disabling processing after reduction of the rotation speed of the rotary polygon mirror is started.

A laser scanning unit (LSU) identification method and an image forming device are provided. The image forming device includes a processor and a target LSU, where the target LSU includes a laser diode, a laser diode drive unit, a polygon mirror, and a motor. The method includes providing a signal related to a quantity of reflective surfaces of the polygon mirror to the processor by the target LSU; identifying the quantity of the reflective surfaces of the polygon mirror of the target LSU according to the signal related to the quantity of the reflective surfaces of the polygon mirror provided by the target LSU, and determining a control parameter of the target LSU according to an identified quantity of the reflective surfaces by the processor, thereby controlling the target LSU according to the control parameter; and operating according to the control parameter by the target LSU.

In one example, a method of fabricating a polygon assembly of a Light Detection and Ranging (LiDAR) module is provided. The method comprises: forming, on a backside surface of a first silicon-on-insulator (SOI) substrate, a multi-facet polygon of the polygon assembly; forming, on a frontside surface of the first SOI substrate, an axial portion of a support structure of the polygon assembly, the axial portion forming a stack with the polygon along a rotation axis; forming, on a frontside surface of a second SOI substrate, a plurality of radial portions of the support structure; forming, on a backside surface of the second SOI substrate, a cavity that encircles the plurality of radial portions; and bonding, based on a wafer bonding operation, the axial portion to the plurality of radial portions to form the polygon assembly.