Abstract: An image forming apparatus includes a light source that emits light beam; an illumination-current generating unit that generates an illumination current that causes the light source to emit the light beam; a deflecting optical unit, thereby forming a light spot and scanning the scanned surface; a detecting unit that detects a scanning position of the light spot on the scanned surface; a control unit that calculates a relation between a value of the illumination current and an intensity of light based on a plurality of intensities of emitted light, each intensity of the plurality of intensities being close to or equal to a prescribed light intensity, and causes the illumination-current generating unit to generate the illumination current based on the relation.

Abstract: A light emitting device includes a plurality of light emitting elements, a first storage unit that stores first correction values corresponding to the light emitting elements, a counting unit that counts the number of pixels whose gray-scale values designated by image data are within a predetermined range included in an image, a selection unit that selects a first mode or a second mode according to the relationship between the number counted by the counting unit and a threshold value, and a driving unit that drives the light emitting elements corresponding to the predetermined number of pixels to emit amounts of light corresponding to the first correction values when the first mode is selected by the selection unit, and drives the light emitting elements corresponding to the predetermined number of pixels to emit amounts of light corresponding to the image data when the second mode is selected by the selection unit.

Abstract: A method is provided for forming an image of a pattern of features on media with radiation beams emitted by an imaging head while scanning over the media along a scan direction. The method includes determining a pitch of a pattern of features along a first direction and controlling the imaging head to selectively emit the radiation beams to form the pattern of features on the media with a plurality of pixels that can include imaged pixels and non-imaged pixels. The plurality of pixels can include a first pixel having a first size along the scan direction and a second pixel having a second size along the scan direction. The second size can be different from the first size and is determined based at least on the pitch of the features along the first direction and the first size.

Abstract: A label pattern can be created on a label side of an optical disc under well focus control. An optical disc is first loaded in an optical disc drive with the label side thereof facing to an optical head of the optical disc drive. Then, the optical head is actuated along a focusing direction. Meanwhile, a light intensity addition signal is generated in response to optical signals reflected from the optical disc and received by the optical head. A closed-loop control operation of the optical head is performed according to the light intensity addition signal after the light intensity addition signal up-crosses a threshold. Then, a label pattern can be defined on the label side of the optical disc with the closed-loop control operation.

Abstract: A multi-beam image forming apparatus is disclosed in which a semiconductor laser array including plural semiconductor laser elements serves as an optical beam generation unit. The apparatus includes a printing ratio counting unit that counts printing ratios of the semiconductor laser elements in plural printing areas divided in a scanning direction based on image data transmitted from a host unit; and a light amount control unit that controls emission light amounts of the semiconductor laser elements based on a result from the printing ratio counting unit. The light amount control unit calculates droop correction values corresponding to the printing areas from the printing ratios of the semiconductor laser elements based on the printing ratios in the printing areas counted by the printing ratio counting unit so as to correct the light amounts of the semiconductor laser elements.

Abstract: The present invention relates to a system for optically adjusting a computer-to-plate (CTP) imaging head which includes an a light source (104), optical fiber (124) for transmitting light emitted from the light source; an imaging lens (204) for focusing light emitted from a distal end of the optical fiber (128) on a substrate; wherein a portion of light striking the substrate is reflected back to the distal end of the optical fiber; a fiber optic coupler (116) in the optical fiber which transmits the reflected light to a light detector (112); wherein the light detector measures intensity of the reflected light; and a control unit configured to adjust the imaging head according to the intensity of the reflected light.

Abstract: A disclosed device for optically scanning a target surface includes a light source unit configured to emit a light beam; a light intensity detecting unit; a coupling unit configured to substantially collimate the emitted light beam; a beam limiting unit configured to limit the amount of the collimated light beam; a beam splitting unit configured to split the beam limited light beam and thereby to cause a first portion of the beam limited light beam to enter the light intensity detecting unit, wherein the light intensity detecting unit is configured to detect the intensity of the first portion of the beam limited light beam; and a beam deflecting unit configured to deflect a second portion of the split light beam toward the target surface. In the disclosed device, the beam limiting unit and the beam splitting unit are integrated as a single unitary structure and positioned between the coupling unit and the light deflecting unit.

Abstract: A device is provided for setting up, adjusting, and/or controlling an apparatus that cyclically processes printed products. The device includes a lighting unit having at least one light source directed toward a processing area of the apparatus. The light source is controllable to selectively generate a continuous light or a flashing light synchronized with a processing cycle of the apparatus.

Abstract: An optical writing unit includes a light-emitting-element array in which a plurality of light emitting elements is arranged and an optical system that guides light flux emitted from the light emitting elements as a light spot. A result of comparison of a property value of the light emitting elements at a predetermined threshold in an exposure intensity distribution of the light emitting elements is within a preset range over an entire effective image area. An emission condition of the light emitting elements is set such that a fluctuation of amounts of exposure of the light emitting elements or a result of comparison of the amounts of exposure does not exceed a preset range over the entire effective image area.

Abstract: An image forming apparatus is provided with a modulator producing a modulated signal of a pulse width decided on given image data and a driver driving an optical generator such as laser to generate a light beam. The image forming apparatus is further provided with a scanner periodically scanning the light beam generated by the optical generator and a power detector detecting information indicative of a power of the light beam scanned by the scanner. A pulse width adjustor uses the information detected by the power detector, in order to adjust the pulse width of the light beam.

Abstract: An image forming apparatus includes light sources, a light intensity controller, an optical writing unit, a controller, and an image forming unit. The light sources are switchable between activated and deactivated conditions according to supplied image data. The light intensity controller controls light intensity of the light sources. In the optical writing unit, light beams output from the light sources are deflected in a main scanning direction. The controller sets a given number of light sources to activated condition to write a latent image on an image bearing member according to an image forming line speed. The controller instructs the given number of light sources to emit light beams onto an image area on the image bearing member, and instructs all of the light sources to emit light beams at a blank area on the image bearing member to execute a light intensity control for all of the light sources.

Abstract: A method of manufacturing integrated circuits includes measuring a reflectivity value of a wafer. An optimum energy level for laser marking the wafer is determined using the reflectivity value. A laser beam having the optimum energy level is then emitted to make laser marks on the wafer.

Abstract: Aspects of the disclosure provide a method for improving performance of a raster output scanner (ROS) system with a reduced cost. The method can include identifying a current mirror facet of a motor polygon assembly (MPA) including multiple mirror facets that each mirror facet has a reflectivity characteristic, determining a driving signal based on the reflectivity characteristic of the current mirror facet and a performance characteristic of a light source, and driving the light source based on the driving signal to emit light that is reflected by the MPA onto a photoreceptor.

Abstract: A method of adjusting an exposure device suited for an electrophotographic printer, the exposure device includes a plurality of light-emitting elements. The method includes the steps of energizing selected light-emitting elements according to a selection scheme, using a pre-determined energy level for energizing each selected light-emitting element and obtaining a corresponding exposure intensity distribution from the exposure device. The method further includes the steps of predicting a toner area coverage distribution, based on the obtained exposure intensity distribution and on a pre-established transfer function, obtaining an attribute of the predicted toner area coverage distribution and determining the setting values for the energy levels for energizing each selected light-emitting element such that the obtained attribute becomes a target attribute.

Abstract: An exposure device for a non-impact printing apparatus which includes a plurality of light-emitting elements for forming images, a driver element for individually applying energy output levels to the light-emitting elements, lens for focusing the light emitted by the light-emitting elements, storage ability for storing a list of setting values for setting the energy output levels, wherein the list includes a plurality of series of setting values, each one of the series enabling to attribute at least one setting value to each one of the light-emitting elements, each one of the series being selectable as a function of an exposure device condition. A method is also provided for adjusting a non-impact printing apparatus which includes the step of selecting the most adequate series of setting values on the basis of an analysis of the optical density of printed images on a receiving medium.

Abstract: An image forming apparatus is capable of controlling an exposure in accordance with sensitivity variations of a photosensitive body. An actual exposure position (Pr) sometimes precedes an exposure position (Pc) recognized based on the count value (C). In this case, the correction value (Dc) of the exposure position (Pc) recognized based on the count value (C) is calculated by linear interpolation using reference correction values (D0?Dn) corresponding to the position until the home position (HP) of a photosensitive drum is detected. When the home position (HP) is detected, the correction value (Dc(Pc0)) of an exposure position (Pc) recognized after detecting the home position (HP) is so calculated as to make the difference between the correction value of the exposure position and that of a previous exposure position (Pn?) fall within a preset range (?).

Abstract: A rotating deflection unit deflects a laser light emitted from a light-emitting element and performs a scanning with the laser light. A light-intensity detecting unit detects a light intensity of the laser light. A current control unit controls a current to be supplied to the light-emitting element so that the light intensity of the laser light reaches a target light intensity. An initializing unit determines an initial current value with which the target light intensity is obtained from the light-emitting element by eliminating an influence of a noise caused by a reflected light input into the light-intensity detecting unit from the rotating deflection unit.

Abstract: A light amount correcting method for a light emitting apparatus having a plurality of light emitting devices, includes: measuring light amount values of a plurality of the light emitting devices; extracting high frequency components from the measured light amount values; extracting low frequency components from the measured light amount values; calculating a first correction value for correcting a light amount value of a first light emitting device on the basis of the high frequency components; and correcting a second correction value for correcting the light amount value of the first light emitting device on the basis of the low frequency components; and correcting a light amount value of a second light emitting device such that it is included in both of the first allowable range and the second allowable range.

Abstract: An optical scanning apparatus includes a plurality of light sources capable of emitting light. A detection unit detects a light quantity of the light emitted from the plurality of light sources. A control unit controls drive current of a light source designated as a control object based on a detection result obtained by the detection unit. The control unit controls the drive current based on an activation state of the light source designated as the control object and an activation state of a light source other than the control object.

Abstract: An image forming apparatus includes light source having multiple light-emitting portions, rotating polygonal mirror which deflects a beam that is emitted from light source, and photosensitive member which is exposed by beams in an image period that is included in one scanning cycle of the beam. One scanning cycle of the beam includes an image period and a non-image period. This apparatus includes selection unit which selects one or more light-emitting portions to be used in image period from among multiple light-emitting portions, and driving unit which drives selected light-emitting portions to emit a beam in a non-image period that is immediately before image period. This apparatus further includes control unit which executes auto light power control for one or more light-emitting portions to be used in image period according to light power of beams detected by beam detection unit.

Abstract: A control method for controlling an optical head having a plurality of light emitting devices, includes: dividing the plurality of light emitting devices into a plurality of blocks by grouping adjacent light emitting devices of the plurality of light emitting devices; adjusting levels of driving signals supplied to the adjacent light emitting devices for each of the plurality of blocks so that emission luminances of the adjacent light emitting devices belonging to the each of the plurality of blocks become substantially equal to each other; and adjusting emission periods so that the equalized emission luminances of the plurality of blocks become substantially equal to each other.

Abstract: A method and system for a color xerographic machine determines a lower bound for the ROS power levels so that color defects are not produced by light attenuation from one or more layers of toner particles on a latent image. The method computes a minimum ROS power level for the photoreceptor at its maximum and minimum charge levels. The minimum ROS power level is the level at which the discharge voltage does not drop beyond a maximum discharge voltage difference. The difference is related to a toner particle density that affects color reproduction. The minimum ROS power levels for the minimum and maximum photoreceptor charge levels are used to compute a functional relationship for minimum ROS power levels at other photoreceptor charge levels. Thereafter, the minimum ROS power level function may be used to compute minimum ROS power levels for other photoreceptor charge levels. The computed minimum ROS power levels may be used to control the power levels used during color reproduction performed by the machine.

Abstract: A drive signal for driving a semiconductor laser is generated on the basis of an image signal inputted in synchronism with a pixel clock. A bias signal to the semiconductor laser is generated at a timing earlier than the drive signal by a predetermined time. The bias signal is disabled in synchronism with the leading edge of the drive signal.

Abstract: An image forming apparatus forms an image by laser beams from a plurality of lasers. The image forming apparatus includes a light amount control circuit that detects displacement in a sub-scanning direction of the main scanning line of a laser beam from the predetermined laser, from a reference position. The apparatus decides an allotted amount of light for each of the plurality of lasers in accordance with the detected displacement and controls to drive each of the plurality of lasers in accordance with the decided allotted amount of light for each laser.

Abstract: An image recording apparatus (1) causes a recording head (20) to move through a distance corresponding to one half of the recording width of the recording head (20) in a sub-scanning direction each time a recording drum (10) makes one rotation. This, light emitting devices (23, 24) record two line data in advance, and thereafter following light emitting devices (21, 22) record the same line data repeatedly at the same position. This increases the energy of laser light beams given to a recording position on a printing plate (P) to accomplish the recording of an image with reliability. The recording speed is not extremely decreased because not all light emitting devices (21 to 24) are used to make the repeated recordings at the same position on the printing plate (P). Further, the construction of optical systems and driving systems in the image recording apparatus is not complicated.

Abstract: Laser beam scan line nonlinearity is compensated for by providing algorithms for generating linearity profiles which are used by a corresponding registration system in an electrophotographic device to determine the placement of Pels across a scan line.

Abstract: As a scanning light beam which is scanning and traveling away from an effective image region moves passed the location of a sensor, a horizontal synchronizing signal Hsync is obtained as a first detection signal. A deflection mirror surface turns around, thereby reversing the direction in which the scanning light beam scans. This scanning light beam therefore scans an effective image region IR, and a latent image forming operation using this scanning light beam is controlled based on the horizontal synchronizing signal Hsync. Hence, there is a relatively long period of time (T4+T5) since the horizontal synchronizing signal Hsync is obtained until formation of a latent image starts in accordance with the signal Hsync. This secures sufficient time for control of the latent image forming operation based on the horizontal synchronizing signal Hsync, and hence, realizes the latent image forming operation as desired during the time T6.

Abstract: A reference developing image is formed on a photoreceptor drum under an image forming condition measured in advance, and the density of this reference developing image is detected. A development bias voltage is corrected based on the detection result, and when a correction value of the development bias voltage exceeds a predetermined range, a reference output voltage of an ATC sensor for detecting the density of toner in a developing device is corrected based on the detected value of humidity around the developing device, the frequency of use of the apparatus, and the agitation stress of developer.

Abstract: The invention is directed to the provision of an exposure apparatus in which is stored an electric current value appropriately determined for supply to a light-emitting device, and a method for producing such an exposure apparatus. The production method according to the invention comprises the steps of supplying a reference electric current to the light-emitting device, and measuring the amount of light from each of the plurality of pixels of the light modulating device, determining whether a minimum value among the amounts of light measured from the plurality of pixels lies within a predetermined range, and determining the value of the electric current to be supplied to the light-emitting device so that the minimum value of the amounts of light falls within the predetermined range when the minimum value of the amounts of light is outside the predetermined range.

Abstract: Image forming units each form an image of one color, which are superimposed to form a color image, and a pattern used for correcting deviation of the image. A first detector positioned at an image writing starting side, and a second and a third detector each detects the pattern. A first and a second correcting unit having different precisions correct a deviation of an image writing position based on detection by the first, second, and third detectors. A third and a fourth correcting unit having different precisions correct a total-width magnification error based on detections by the first and the third detectors. The fourth correcting unit further corrects a partial magnification error.

Abstract: A method for detecting and optimizing the quality of a mark made by a laser on a recording medium, comprising (a) recording a test mark at a selected level of laser power and a selected speed of movement of the recording medium, (b) measuring at least one dimension of the test mark, (c) comparing the at least one dimension of the test mark to a stored reference value for at least one reference dimension, and (d) determining whether the at least one dimension of the test mark is comparable to the at least one dimension of the stored reference value.

Abstract: In an optical control apparatus, a semiconductor laser emits a laser beam having a power corresponding to an energizing current. A light power detecting device detects a light power of the laser beam. A monitor voltage generating device generates a monitor voltage set based on the light power. A reference voltage generating device generates a reference voltage set based on a target light power of the laser beam. A current control device controls the energizing current such that the monitor voltage approaches the reference voltage based on a deviation of the monitor voltage from the reference voltage. A pseudo voltage input device inputs a predetermined pseudo voltage to the current control device instead of the monitor voltage under a predetermined condition such that a variation range of the deviation lies within a predetermined range.

Abstract: Methods are provided for an EP device such as a laser printer or copier, to compensate for variations in scanning rate. At intervals during a scanning process, actual scanning rate is measured and compared to a basal scanning rate of the EP device. Adjustments in the laser light source intensity are then implemented to preserve a predetermined image darkness notwithstanding variations in scanning rate, thereby preserving print quality. To implement the adjustments, a compensation factor is calculated based on a difference between the basal scanning rate of the device and the measured actual scanning rate. The steps of measuring an actual scanning rate, calculating a compensation factor, and adjusting laser operating intensity may be performed during a warming-up function at EP device at start-up, during a print job, or both. An EP device utilizing the method of the present invention is provided also.

Abstract: A correction value determining method for each of a plurality of electro optical elements whose light intensity is controlled in accordance with a gray scale value and a correction value, the method comprising the steps described below. (a) Measuring a light intensity of the each electro optical element when the same gray scale value is specified to each of the electro optical elements. (b) Determining the correction value for each of the plurality of electro optical elements so that a light intensity after correction of one of the electro optical elements when a predetermined gray scale value is specified thereto whose light intensity measured in step (a) is a first light intensity exceeds a light intensity after correction of another one of the electro elements when the predetermined gray scale value is specified thereto whose light intensity measured in step (a) is a second light intensity which exceeds the first light intensity.

Abstract: A scanning time is divided by the number of sides of a polygon mirror to obtain a value N. Then, it is determined whether an error has occurred. When no error has occurred, the value N is stored in an NVRAM, and a magnification correction value is calculated. Values M and N of a PLL are set based on the correction value. A difference between a clock set by the PLL and an ideal pixel clock frequency is corrected to an optimal magnification by changing a phase. The ideal pixel clock frequency after magnification correction is calculated from V=N0/N×F. The values M and N of the PLL that provide a frequency closest to the ideal frequency V are acquired. A difference between a frequency V? acquired from the values M and N and the ideal pixel clock frequency V is corrected by the clock phase.

Abstract: A system and method for improving FIB milling endpointing operations. The methods involve generating real-time images of the area being milled and real-time graphical plots of pixel intensities with an increased sensitivity over native FIB system generated images and plots. The images and plots are generated with raw signal data obtained from the native FIB system. More specifically, the raw signal data is processed according to specific algorithms for generating images and corresponding intensity graphs which can be reliably used for accurate endpointing. In particular, the displayed images will display more visual information regarding changes in milled material, while the intensity graphs will plot aggregate pixel intensity data on a dynamically adjusting scale to dramatically highlight relative changes in milled material.

Abstract: A method for setting a laser power of an optical disc drive is provided. To perform a label-printing operation on a label surface of an optical disc, an optical pickup unit is shifted to a control feature zone of the label surface, and a laser power operation is performed prior to initiating label printing using power setup data and sensitivity related to an internal laser diode sensor of the optical pickup unit detected during manufacture of the optical disc drive. Alternatively, power setup data associated both a data surface and a label surface of the optical disc may be detected and stored during manufacture of the optical disc drive, and a laser power of predetermined magnitude may determined based on the power setup data previously stored in association with the seated surface of the optical disc. The power setup data may be represented by a substantially linear equation relating the input voltage to the output laser power.

Abstract: In this light beam synchronization detector, an enable circuit 34 outputs a first control signal Se1 to an output circuit 35 when at least one of the absolute values of a voltage signal V1 from a first amplifier 31 and a voltage signal V2 from a second amplifier 32 exceeds the absolute value of a threshold voltage ?Vth, thereby putting the output circuit 35 into an operative state. The enable circuit 34 outputs a second control signal Se2 to the output circuit 35 when both the absolute values of the first output voltage V1 and the second output voltage V2 are equal to or lower than the absolute value of the threshold voltage ?Vth, thereby putting the output circuit 35 into an inoperative state. This light beam synchronization detector can prevent the occurrence of an error in the detection timing of a light beam due to a change in the quantity of light of the light beam and preventing the occurrence of erroneous detection due to reflected light.

Abstract: An optical scanning apparatus includes a light source and a structure for performing light-power control for the light source, the structure including a light-power-detection optical unit that establishes an optically conjugate relationship between a deflecting surface of a deflecting unit and a light-receiving surface of a light-power detector in a main-scanning plane. Accordingly, the storage time of a light beam on the light-power-detection optical unit is increased and variation in the power of light emitted by the light source due to heat generated by the light source and environmental variation is accurately detected.

Abstract: In a laser beam printer, even when an inexpensive CPU having low throughput capacity is used, stable power can be obtained by following a sudden change in temperature of a laser chip. A control unit sets a scanning cycle for performing the automatic power control based on ambient temperature of a photoconductive drum and the number of continuously-printed sheets. Then, the control unit output a horizontal synchronizing signal to a laser driving circuit and causes a laser scan unit to output a scanning laser beam. Substantially, when scanning corresponds the scanning cycle, the automatic power control is performed based on an output signal of a photodiode. When scanning does not correspond to the scanning cycle, a horizontal synchronizing signal of the next line is output. Whereby, the scanning cycle for performing the automatic power control according to a change in temperature of the laser chip, thereby reducing loads applied to the control unit.

Abstract: An image forming apparatus is provided with a modulator producing a modulated signal of a pulse width decided on given image data and a driver driving an optical generator such as laser to generate a light beam. The image forming apparatus is further provided with a scanner periodically scanning the light beam generated by the optical generator and a power detector detecting information indicative of a power of the light beam scanned by the scanner. A pulse width adjustor uses the information detected by the power detector, in order to adjust the pulse width of the light beam.

Abstract: In the light amount correction in the main scanning direction, sets of correction values of black and cyan for which the reflection frequency of optical elements are equal to an even number of times are made common to each other (a correction value set—KC), and sets of correction values of magenta and yellow for which the reflection frequency of optical elements are equal to an odd number of times are made common to each other (a correction value set—MY), whereby sets of correction values stored in a correction value storage portion in a correction value setting portion are reduced to two sets. Furthermore, in connection with this, the number of DA converters is reduced to two DA converters of a DA converter—K, C and a DA converter—M, Y.

Abstract: Illumination utilizing a plurality of light sources is disclosed. In one embodiment, an illumination level is set to result in a desired contrast level. Calculations are made to derive electrical current values for each of the plurality of light sources which will illuminate a plurality of selected locations at the set illumination level.

Abstract: An image forming apparatus is provided with a modulator producing a modulated signal of a pulse width decided on given image data and a driver driving an optical generator such as laser to generate a light beam. The image forming apparatus is further provided with a scanner periodically scanning the light beam generated by the optical generator and a power detector detecting information indicative of a power of the light beam scanned by the scanner. A pulse width adjustor uses the information detected by the power detector, in order to adjust the pulse width of the light beam.

Abstract: A method and apparatus for controlling light intensity from two or more light sources. A timing scheme is used to modulate the light sources. Light from the light sources is combined to form a beam and a photo-sensor senses the beam. In a time interval when only one of the light sources is activated, the signal from the photo-sensor is monitored and used in a feedback control circuit to control the active light source.

Abstract: The dynamic range of an electrophotographic device may be shifted by calibrating a laser power of a laser source to operate within a first range of power levels during a laser power adjustment operation. At least one laser control parameter is modified after calibrating the laser power so that the laser source is operable within a second range of power levels different from the first range of power levels and a beam emitted by the laser source is controlled within the second range of power levels when the beam is directed towards an image area of a photoconductive surface.

Abstract: Disclosed an image forming apparatus equipped with an exposure section including a plurality of LED elements, the apparatus forming an electrostatic latent image on a photosensitive body with the exposure section, the apparatus including: an RFID tag provided in the exposure section, the RFID tag including a light quantity correction data storing section and a communication section to perform wireless communication; an RFID reader/writer to perform the wireless communication with the RFID tag; a control section to allow the RFID reader/writer to perform the wireless communication with the RFID tag so as to read or write the light quantity correction data from/to the light quantity correction data storing section of the RFID tag during a period when no processing related to the image data is being performed; and a storage section to store the read light quantity correction data.

Abstract: The present disclosure includes systems and techniques relating to pulse laser printing. In general, in one implementation, an apparatus includes: a laser operable to produce a pulsed printing beam; an optics assembly operable to focus and direct the pulsed printing beam; and electronics communicatively coupled with the laser and the optics assembly, the electronics being operable to control the laser and the optics assembly to generate power pulses of the pulsed printing beam in synchronization with a series of moves that steer the pulsed printing beam in a non-raster scanning pattern to predefined locations on a material to alter an optical characteristic of the material at the predefined locations, which are arranged to form at least a portion of a symbol. The electronics may deliver the power pulses in synchronization with arrival at the predefined locations, and the electronics may be configured to receive sensed feedback in a closed loop.

Abstract: A laser scanning device includes a semiconductor laser that emits a laser beam, a laser power detector that detects laser beam power of the semiconductor laser, a reference voltage generator that generates reference voltage for controlling the laser beam power of the semiconductor laser in accordance with a laser power control signal provided from an external device, and a laser driver that compares the reference voltage generated by the reference voltage generator and the laser beam power detected by the laser power detector to control a driving current supplied to the semiconductor laser for emitting the laser beam. The laser scanning device further includes an abnormal condition detector that detects the laser power control signal received by the reference voltage generator.

Abstract: An apparatus for switching and controlling the intensity of a laser beam directed toward a beam detect sensor for an image forming device. A printing power reference signal and a beam detect power reference signal is selectively connected to a laser driver through a first switch. A printing power reference holding capacitor and a beam detect power reference holding capacitor is selectively connected to the laser driver through a second switch that is controlled in tandem with the first switch. During each scan cycle, the output laser power is monitored and used to adjust one of the two holding capacitors based such that both the printing power and the beam detect power have a controlled reference.