Abstract: A disclosed optical scanning apparatus for scanning a scanning surface using a light beam, the optical scanning apparatus comprises: a light source having a plurality of luminous sources; a deflection unit collectively deflecting a plurality of light beams emitted from the plural luminous sources; a light guiding unit guiding at least a portion of each of the plural light beams to a predetermined direction without using the deflection unit; and a photo-detection system receiving the plural guided light beams and the plural deflected light beams and outputting a signal based on the received light beams.

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 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: A line head includes a plurality of the light emitting element columns which has a main light emitting element column exposing a light amount necessary for exposure to an image carrier and an auxiliary light emitting element column exposing the image carrier so as to obtain the light amount necessary for exposure even when a light emitting element having a pixel defect is existed in the main light emitting element column. Also, a line head includes a plurality of the light emitting element columns. The light emitting element columns includes a main light emitting element column exposing an image carrier and an auxiliary light emitting element column exposing the image carrier when a light emitting element having a pixel defect is existed in the main light emitting element column.

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: To provide an exposure device and an image forming apparatus using the same, in which the exposure device can detect light intensity with improved reliability and thereby controls the light intensity with high precision, the exposure device includes an EL (electro-luminescence) element having a first electrode (an anode), a second electrode (a cathode), and a light emitting layer disposed between the first and second electrodes, thereby forming a light emitting unit, and a light detecting element detecting light emitted from the EL element, in which the EL element and the light detecting element are stacked onto each other. The light detecting element is provided at an inner side of a principal surface of the electrode (the anode) which is disposed closer to the light detecting element than the other electrode. A light emitting area of the EL element is provided at an inner side of a principal surface of the light detecting element.

Abstract: A line head, includes: a substrate which is transmissive and includes a first surface and a second surface facing the first surface; a plurality of light emitting elements which are arranged on the first surface of the substrate and emit light beams; a wiring which is arranged on the first surface of the substrate and is connected with the plurality of light emitting elements; a lens array that includes a plurality of imaging lenses which are arranged facing the light emitting elements at a side of the second surface of the substrate and focus the light beams emitted from the facing light emitting elements to form spots; and an optical sensor which detects the light beams emitted from the light emitting elements and is arranged on the second surface of the substrate.

Abstract: An image forming apparatus illuminates a pixel formation member with optical energy according to image data specifying a value for each pixel in the image. Some of the optical energy emitted to form a pixel is distributed over surrounding pixels; similarly, a pixel may receive peripheral optical energy that was emitted to form surrounding pixels. The amount of peripheral optical energy thus received is calculated, and the amount of optical energy emitted to form the pixel is adjusted to compensate for the peripheral optical energy, so that the total optical energy received by the pixel has the intended value. Image irregularities are thereby avoided, even if the image formation apparatus employs multiple light-emitting elements with different energy emission distributions.

Abstract: Various exemplary embodiments include an electrostatographic printing apparatus and a method of correcting one or more associated uniformity profiles. In various exemplary embodiments the apparatus includes first and second actuators. In various exemplary embodiments the method includes measuring an image and generating at least one corresponding TRC, generating a charge profile, subtracting a reference patch density from a patch value to obtain a difference profile, converting the difference profile to a ROS intensity profile and an LED intensity profile, and iteratively repeating the steps of measuring, generating, subtracting and converting until within an acceptable range.

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: An imaging apparatus for imaging on a recording medium is improved to permit the imaging power to be balanced between various groups of individual radiation sources with a low outlay and high accuracy. Two or more imaging heads that respectively include a multiplicity of individual radiation sources that can be electrically driven individually with light beams directed onto a radiation-sensitive layer of the recording medium. A drive moves the recording medium and the radiation sources relative to one another. A control device controls the power of the light beams of the radiation sources separately for each imaging head. A least one light guide is provided that guides a portion of the light beams emanating from the radiation sources to the receiver surface of a photoelectric sensor, which sensor is connected to the control device.

Abstract: A light source driving device which drives a plurality of light emitting parts provided in a light source to emit a plurality of light beams based on image information, includes a plurality of driving circuits configured to drive the plurality of light emitting parts. Each of the driving circuits includes a signal generation circuit that generates a modulation signal to control a light emitting intensity of the corresponding light emitting part based on the image information, a detection circuit that detects a light emitting status of the corresponding light emitting part; and a light emitting circuit that outputs a driving signal to the corresponding light emitting part to emit a light beam in accordance with the modulation signal and adjustment data obtained based on the light emitting status of at least one of the plurality of light emitting parts.

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: 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: A shape or position of a shielding member is set corresponding to an image focusing property of each rod lens element to prevent an MTF from deteriorating, to provide a clear exposure image, and to prevent a defective image such as having a vertical streak or the like, from occurring on a printed image. To achieve the above, an exposure device used for an image forming apparatus of an electrophotographic type, comprises a lens array having a plurality of lens elements for condensing light from a light source onto a photosensitive drum; and a shielding member for shielding at least one portion of a peripheral portion with respect to a direction of an optical axis of each lens element from the light radiated from the light source, wherein the shielding member has a shape or a position set depending on an image focusing property with each lens element.

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: In a printing system, a method is used for adjusting currents to LEDs in an LED printbar to achieve uniformity of the print. The line test pattern and halftone strips test pattern are printed. The test patterns are scanned. An LED line metric of each LED test pattern line and reflectance uniformity of each halftone test strip are measured. A line uniformity difference profile and a set of halftone strips uniformity difference profiles are concurrently calculated. A current value supplied to each LED associated with the test patterns is adjusted to simultaneously optimize the uniformity in the lines test pattern and the halftone strips test pattern.

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: An image forming apparatus in which a BD signal, which is a main-scanning reference signal, and image data are input to an image signal generating unit. Using a converting unit, main-scanning coordinate information, output from a main scanning coordinate measuring counter, and correction amounts, recorded in a correction amount LUT, are referred to, to convert a proper amount of image data. Here, the converting unit performs calculations in accordance with the main-scanning coordinate information, to obtain the image data of correction amounts that differ in accordance with coordinates. The correction amounts are in correspondence with different amounts of driving current in a main-scanning direction. Therefore, laser light emission, which provides a light quantity in accordance with the image data, is controlled.

Abstract: The invention is directed to the provision of an exposure apparatus that can determine a correction value for each individual light-emitting part by employing a method that detects the amount of light corresponding to one particular light-emitting part from composite light containing light rays from adjacent light-emitting parts, and also to the provision of a method for producing such an exposure apparatus.

Abstract: A light beam scanning device is disclosed that includes a light emission source to emit a light beam, a deflection part to deflect the emitted light beam in the main scanning direction, first and second light beam detection parts to detect the deflected light beam at first and second positions, respectively, outside an image area on the opposite sides thereof in the main scanning direction, a time difference measurement part to measure the time difference between the light beam detections by the first and second light beam detection parts, and a control part to perform control so as to correct image magnification in the main scanning direction in the image area from the measured time difference. The control part performs control so that the condition of the amount of light at the time of detecting the light beam by the first and second light beam detection parts is constant.

Abstract: A method for calibrating a printer including a light-emitting diode (LED) printhead for non-uniformity on an image plane. The LED recording elements are arranged in a plurality of arrays. A plurality of characteristics (102, 104, 106, 108, 110) associated with each recording element are measured and from the measured characteristics a plurality of parameters (112, 114, 116, 118, 120) associated with each recording element is determined. Adjustment factors for a plurality of parameters are combined mathematically to determine an adjusted power density (122) for each recording element on the image plane. Correction factors (130) are then assigned to each recording element to correct for the adjusted power density (122). The correction factors (130) are stored in a memory (132) associated with the LED printhead.

Abstract: An adjustment quantity required for adjusting a quantity of light emission is computed based on an image density calculated from a measured quantity of light emission and sensitivity characteristics of an exposed photosensitive material to be exposed so that the image density of each of the light emitting devices within a device row becomes substantially equal to each other and the quantity of the light emission is adjusted based on the computed adjustment quantity.

Abstract: An image exposing apparatus forms an image on photosensitive material by the technique of exposing and forming an image through direct modulation of a semiconductor laser device. The exposing apparatus includes a beam scanning unit for scanning a beam emitted from a semiconductor laser device to photosensitive material, a laser driving unit for driving the semiconductor laser device, the laser driving unit being operable to vary its driving current to the semiconductor laser device in accordance with a received image signal, and a laser output controller operable to measure current-beam output characteristics of the semiconductor laser device over a predetermined current range and then set a correlation between the image signal for the laser driving unit and the driving current for the semiconductor laser device, based on the measurement information.

Abstract: The present invention provides a compact printer that can print images of high quality even if the images are printed successively. A temperature at the time of turn-on is detected by a temperature sensor, and a CPU estimates the temperature of an exposure head at the start of exposure based on the detected temperature. The CPU creates print data by referring to a look-up table in accordance with the estimated temperature and drives the exposure head in accordance with the print data, thereby forming a latent image on an instant film sheet.

Abstract: The invention concerns an image recording apparatus suitable for forming a medical image that is used for a medical diagnosis, and a test pattern for evaluating a quality of the medical image. The image recording apparatus includes a printing section to either the medical image or the test pattern on the recording medium, based on image date; a printing-condition setting section to set a printing condition for printing the test pattern; and a printing-condition displaying section to display the printing condition set by the printing-condition setting section. The printing section prints at least one of a sharpness-evaluating pattern and a granularity-evaluating pattern.

Abstract: The image recording apparatus scans a heat mode recording material with a light beam modulated in accordance with image information, to thereby record an image on the heat mode recording material. The apparatus includes an unit for generating a modulated signal, an unit for generating an additional signal at a timing of at least one of rising and falling of the modulated signal and a unit for generating a drive signal by adding the additional signal to the modulated. The image forming method and apparatus scan a photosensitive material with the light beam to record an image, and a power of the light beam is set to a power of a level at which a recording line width or a recording dot size, which is determined depending upon a threshold value for the photosensitive material to blacken, is substantially fixed even if defocus occurs.

Abstract: An image quality detecting apparatus detects image quality based on a specified image pattern formed on an image carrier. This apparatus includes a light-emitting device that radiates a spotlight on the image carrier, a lens, a scanning unit that scans the image pattern with the spotlight, and a photoelectric conversion element that detects a quantity of light reflected from the image pattern and the image carrier or light transmitted through the image pattern and the image carrier during the scanning. The image quality is detected by setting a diameter of the spotlight at least in a scanning direction to the reciprocal number of a spatial frequency or smaller in which human eyesight is the most sensitive, for example, to 1000 ?m or less.

Abstract: A beam detection sensor detects power of a laser beam from one of a plurality of light sources for each scanning of a scanning section to provide a light power signal. A laser control circuit compares a value of the light power signal with a predetermined value, adjusts a terminal voltage of a capacitor based on a result of the comparison, controls emission power of one of the light sources in accordance with the terminal voltage of the capacitor, and executes the control once for each light source during a plurality of scanning operations. An APC correction circuit corrects a reduction in the power of a laser beam in accordance with a reduction in electric charges applied to the capacitor caused by a leakage current during the plurality of scanning operations.

Abstract: This invention provides an image forming apparatus that can suppress variations in writing densities of LED heads and form stable images. An image forming apparatus has an image retainer 1 for retaining a toner image, an image writing unit 3 equipped with a plurality of LED heads 31 to form a static latent image the image retainer 1, a developing unit 4 for developing the static latent image formed by the image writing unit 3 with a developing agent, a patch formation controller 23 for forming patches for each LED head on the image retainer 1, a density detector 25 for detecting the density of each patch formed by the patch formation controller 23, and a correction controller 26 for correcting the light amount of each LED head by the density detected by the density detector 25.

Abstract: An exposure apparatus for exposing a substrate to a light pulse via a mask. The apparatus includes an array of photoelectric converters to detect the light pulse, and a read circuit to read electrical signals from the array. The read circuit reads electrical signals from a part of the photoelectric converters sequentially switched with respect to each time interval between a successive two of the light pulses thereby to obtain cumulative electrical signals corresponding to a plurality of the light pulses.

Abstract: A printing apparatus 10 exposes an image onto a photosensitive medium 14, having a printhead 20 with a linear array of exposure sources 40, each exposure source 12 operable at a variable intensity. A shuttle mechanism 16 moves the printhead 20 over the photosensitive medium 14 in a reciprocating motion between one end of a carriage assembly 72 and the other. An encoder 38 is coupled to the shuttle mechanism (16) for providing an index encoder pulse 60 at each of a plurality of increments of position of the shuttle mechanism 16 along the carriage assembly 72. Exposure control logic calculates a shuttle velocity according to index signal timing and adjusts the variable intensity of each exposure source 12 according to the shuttle velocity.

Abstract: An image forming device employs a multi-laser beam system in which the light intensity of the second semiconductor laser is adjusted while simultaneously emitting laser beams from both the first and second semiconductor lasers. This configuration makes it possible to reduce the number of change-over circuits indispensable for line APC control of semiconductor lasers by one. Thus the maximum voltage stored in the second peak hold circuit is the voltage generated to light the first semiconductor laser and the second semiconductor laser simultaneously. The voltage generated to light the first semiconductor laser and the second semiconductor laser simultaneously is inevitably larger than the voltage generated to light only the semiconductor laser. For this reason, the second peak hold circuit does not require a separate change-over circuit to switch the circuit from the sampling state to hold state since the voltage stored in the second peak hold circuit is not updated when only the first semiconductor lights.

Abstract: An electro-optical system for adjusting beam to beam power non-uniformity in a multi-beam scanning system is disclosed. The electro-optical system consists of N×M array of light beams and N×M array of photodetectors wherein optical means deflect the light beams onto a photodetector array. A circuit consisting of N×M array of programmable laser drivers programmed with uniformity values for each light beam and having an N×M array of feedback loops is used to adjust the power intensity of each beam through the programmable laser drivers wherein each programmable laser driver uses the photodetector array summed with non-linearity inputs to adjust for beam to beam power uniformity correction.

Abstract: In an image exposing apparatus and an image exposing method, a deterioration of an image quality caused by stray light is suppressed, while both a sensitive level and a non-sensitive level are properly set in accordance with a type of photosensitive material. In the image exposing apparatus, a recording level setting unit calculates a recording level corresponding to a light amount level stored in a recording level light amount memory and sets the calculated recording level. A non-recording level setting unit calculates a non-recording level from an extinction ratio, which corresponds to a type of photosensitive material stored in a photosensitive material information memory, and the recording level. An output voltage setting unit sets an output voltage such that a detected voltage becomes equal to one of the recording level and the non-recording level.

Abstract: In an optical recording apparatus, a detecting section detects disk identification information of an optical disk for selecting a constant which relates to the detected disk identification information. A test OPC section performs test writing operation for OPC at a predetermined linear velocity prior to recording of data so as to obtain a test value. A formulating section formulates an equation expressing a target value in function of a recording linear velocity based on the constant, the predetermined linear velocity and the test value. A running OPC section performs running operation of OPC by monitoring an actual value while irradiating a laser beam for the recording of data at the recording linear velocity. A controlling section controls the power of the laser beam such that the monitored actual value coincides with the target value which is determined by the equation with respect to the recording linear velocity.

Abstract: The present invention uses an open loop feedback technique to control emissive pixels of a printhead of a printer. The open loop feedback technique involves integrating the light intensity of the emissive pixel over a predetermined period of time, averaging the integrated value, comparing the averaged value to a threshold value, and adjusting the input voltage to the OLED of the pixel based on the comparison.

Abstract: An image processing apparatus, comprising: an exposing device for exposing an image forming material so as to form a latent image on the image forming material based on image data; a thermal developing device for developing and visualizing the latent image on the exposed image forming material so as to form an image; a measuring device for measuring the image density of the image on the developed image forming material; a calibrating device for forming a table to define a relation between an image signal and image density on the basis of plural different test image data and measured-image densities thereof; a counting device for counting the number of the image forming material developed within predetermined time; and a controlling device for controlling the exposing device, the thermal developing device, the measuring device, the calibrating device and the counting device; wherein the controlling device stop forming the table for predetermined time when the counting device counts the number of the developed

Abstract: There is described an image-forming apparatus, which can prevent unevenness of an image by controlling the brightness of light-sources. The apparatus includes a light source, including a plurality of light-emitting elements aligned within a predetermined width; an exposure-controlling section to individually control each of intensities of light beams emitted by the plurality of light-emitting elements; and a memory section to store light-intensity compensation data for each of the plurality of light-emitting elements. The image is formed by simultaneously exposing the light beams aligned within the predetermined width onto the photosensitive recording medium, and the exposure-controlling section controls each of the plurality of light-emitting elements based on the light-intensity compensation data concerned, so that each of intensities of the light beams substantially coincides with each of target intensities set in advance.

Abstract: An exposure apparatus reads an electrical signal from a photoelectric sensor by using the time interval between emission pulses even at a high emission frequency of the light source. A photoelectric sensor attached to an exposure apparatus which exposes a substrate to a pulse beam emitted by a light source for generating a pulse beam has a plurality of photoelectric converters. The photoelectric converters are divided into a plurality of blocks. While charges are read from each block by using one time interval between pulse beams, charges in all the photoelectric converters are read by using a plurality of time intervals between pulse beams.

Abstract: With a control device to optimize charge image generation in an electrophotographic process, a light-sensitive and temperature-sensitive photoconductor layer is exposed pixel-by-pixel with a temperature-sensitive light source. The photoconductor layer becomes more sensitive with rising temperature, such that given a predetermined light quantity it discharges deeper. With rising temperature, given the same actuating power, the light source emits a lesser luminous power. The luminous power of the light source and the discharge depth of the photoconductor layer are temperature-dependent via adjustment of the current and/or the luminous duration that flows through the light source and/or the luminous duration. During the measurement of the discharge depth, a temperature measured in the course of the measurement event is used as a reference value for the temperature compensation of the light source.

Abstract: A multibeam exposure device carrying out exposure processing by irradiating, onto an exposure surface of a photosensitive material, an exposure beam obtained by modulating a light beam, by a spatial light modulator and in accordance with an image to be exposed and formed, the multibeam exposure device having: an opening plate having an opening disposed on the exposure surface and blocking light which is other than an object of measurement of light quantity data at the spatial light modulator, the opening allowing passage of the exposure beam which corresponds to a pixel which is an object of measurement of light quantity data at the spatial light modulator; a feeding operation mechanism moving the opening plate such that the opening is moved in a direction intersecting a scanning direction at a time of scan-exposure; and a light-receiving element measuring a light quantity of the exposure beam which passes through the opening.

Abstract: An imaging apparatus includes a controller communicatively coupled to a first laser, a second laser, a scanning device and a light sensor. The controller is configured to perform actions including controlling the first laser, the second laser and the scanning device to simultaneously scan the first light beam and the second light beam across an image region of the photoconductive substrate over a plurality of scans to form a latent image on the photoconductive substrate; activating only the first laser outside the image region between first successive scans of the plurality of scans to sense with the light sensor the first light beam; and activating only the second laser outside the image region between second successive scans of the plurality of scans to sense with the light sensor the second light beam.

Abstract: An exposure head is provided in which light beams from light emitting parts 63 pass through a transparent substrate 62 and are projected on an image carrier. The transparent substrate 62 has plain faces substantially parallel to each other, one of the faces being a face on which the light emitting parts 63 are formed and the other being a face from which light beams are projected. The transparent substrate 62 is provided, at position(s) other than the face on which the light emitting parts 63 are formed and than the face from which light beams are projected, with light quantity detecting means 100 for detecting the quantity of light emitted from said light emitting parts 63.

Abstract: An image quality detecting apparatus detects image quality based on a specified image pattern formed on an image carrier. This apparatus includes a light-emitting device that radiates a spotlight on the image carrier, a lens, a scanning unit that scans the image pattern with the spotlight, and a photoelectric conversion element that detects a quantity of light reflected from the image pattern and the image carrier or light transmitted through the image pattern and the image carrier during the scanning. The image quality is detected by setting a diameter of the spotlight at least in a scanning direction to the reciprocal number of a spatial frequency or smaller in which human eyesight is the most sensitive, for example, to 1000 ?m or less.

Abstract: A movable light beam is controlled and set within a tolerable range of a beam position A by using a galvano-mirror, and then a circuit offset relating to the beam position A is measured. With the circuit offset being subtracted, the movable laser beam is exactly controlled and set at the beam position A, and an output value DA from a sensor at that time is stored. Subsequently, an output value DB from the sensor is similarly stored in connection with a beam position B. An ultimate beam position of the movable laser beam M is controlled such that a difference between the output values DA and DB coincides with a difference between an output value DS of the sensor with respect to a stationary laser beam S and an output value DM of the sensor in connection with the movable laser beam M.