Abstract: The optical sensor includes a light-emitting element configured to emit light to a light emitted surface, a light-receiving element configured to receive reflection light from the light emitted surface, the reflection light including light emitted from the light-emitting element and reflected at the light emitted surface, a circuit board including a mounting surface on which the light-emitting element and the light-receiving element are mounted, and a housing fixed to the circuit board. The housing includes a light shielding portion provided between the light-emitting element and the light-receiving element, and the light shielding portion is engaged with a hole formed in the circuit board at a position between the light-emitting element and the light-receiving element.

Abstract: Certain embodiments provide an image forming apparatus including a photoconductor, a latent image forming portion, an image processing portion, a developer, a transferred body, a sensor that detects an image density of a toner image by the amount of toner attached to a surface and has a sensor characteristic in which a sensor output substantially monotonously decreases according to an increase in the amount of toner, a nonlinear amplifier that has a nonlinear amplification characteristic having one or more inflection points, and enlarges and corrects a value read by the sensor in a range where the sensor output monotonously decreases with respect to the amount of toner by amplification, and an image quality control portion that controls a forming condition of an electrostatic latent image using a correction value of a variation amount of the value at a side where the amount of toner is large in the range.

Abstract: Methods for determining an amount of toner in a target area are provided. In one method, the target area is illuminated with a first light from a first illumination position that is on a first side of a plane that is normal to the target area so that any toner particles in the target area direct a reflected portion of the first light to the first side and a light is sensed at a surface at a sensing position on the first side of the plane to which toner particles at the target area direct the reflected portion of the first light and a sensed light signal is generated that is indicative of the sensed light.

Abstract: Methods for operating a toner printer are provided. In one method a toner image is printed according to first printing instructions. An amount of toner in a target area of the toner image is determined and second printing instructions are generated causing the toner printer to print at least one subsequent toner image based upon the determined amount of first toner.

Abstract: Toner sensor modules are provided. In one aspect, a toner sensor module has a first light source emitting a first light, a first light sensor that generates a sensed light signal that is indicative of a sensed light, and a frame. The frame positions the light source to illuminate a target area from a first side a plane that is normal to the target area so that illuminated portions of any toner particles at the target area direct a reflected a portion of the first light into the first side and positioning the first light sensor on the first side of the plane to which toner particles at the target area direct the reflected portion of the first light.

Abstract: In a reflective optical sensor in an image forming apparatus, an output from each N number of light-receiving elements (N?3), obtained when M number of light-emitting elements (M?3) included in a light-emitting unit emit detecting light, is separated into an amount of specularly reflected light and an amount of diffusely reflected light. The toner density of a pattern, which is formed on a supporting member in the image forming apparatus, is calculated based on a sum of the amounts of specularly reflected light and a sum of the amounts of diffusely reflected light.

Abstract: A toner density sensor comprising: a light emitting element that emits light; a light receiving element that receives reflected light emitted from the light emitting part and reflected at a detection target; a light path for passage of emitted and reflected light formed along the front surface of a printed substrate on which the light emitting element and the light receiving element are surface-mounted; and a diaphragm unit that is formed at and partially narrows this light path, wherein the diaphragm unit is divided into two portions, a diaphragm unit upper-portion and a diaphragm unit lower-portion, and these are disposed in an upper case covering the front surface of the printed substrate and in a lower case covering the rear surface of the printed substrate. In the printed substrate, a through hole is formed for protrusion of the diaphragm unit lower portion from the rear surface to the front surface.

Abstract: According to an embodiment, provided is an image forming apparatus that forms an image on a moving body using toner. The image forming apparatus includes a pattern creating device that creates a first pattern for toner density detection and a second pattern for positional deviation detection on the moving body, the first pattern and second pattern being disposed to be arrayed in a main-scanning direction; a reflecting optical sensor including an emitting system that includes at least three light-emitting elements of which positions at least in the second direction are different and a light-receiving system that includes at least three light-receiving elements that receive light beams that are emitted from the emitting system and reflected from the first pattern and second pattern; and a processing device that obtains toner density information and positional deviation information simultaneously based on an output signal of the light-receiving system.

Abstract: A reflective optical sensor includes a light emitting element to irradiate a target object with a light beam, a light receiving element to receive the light beam reflected by the surface of the target object, a circuit board on which the light emitting element and light receiving element are mounted, a cover element supported on the circuit board to surround the light emitting element and light receiving element, and a light shielding wall provided in the cover element to be a partition between the light emitting element and light receiving element to prevent a part of the light beam from the light emitting element from leaking to the light receiving element. A layer in a certain thickness is formed on the surface of the circuit board along either or both sides of the light shielding wall.

Abstract: A toner amount measuring unit irradiates a toner image formed on an image carrying member with light, and an image capturing unit captures an image of a reflected waveform according to light reflected by the toner image. Then, an amount of applied toner is calculated based on the peak position or peak height of the reflected waveform in accordance with information associated with the density of the toner image to be formed.

Abstract: An optical sensor includes: a light-emitting unit; a light-receiving unit that receives light radiated from the light-emitting unit and reflected from a detection target and that outputs an output value in response to the light received; and a correcting unit that corrects the output value of the light-receiving unit when receiving the light reflected from the detection target based on the output value of the light-receiving unit obtained by irradiating a detection area of the optical sensor with light without any light reflective objects being present in the detection area.

Abstract: A reflection sensor includes the following elements. A light emitting unit emits light to an area of an image forming apparatus where first detection images of plural colors used for detecting amounts of their misregistration are formed. A first light restricting member/configuration restricts light emitted from the light emitting unit. A light receiver is disposed in an optical path of regular reflection light, and receives reflected light and outputs a signal representing an amount of received light. A second light restricting member/configuration is disposed in the optical path of the regular reflection light and restricts light to be received by the light receiver. The value obtained by dividing a diameter of the first light restricting member/configuration by that of the second light restricting member/configuration ranges from substantially 0.5 to 1.9, and the diameters of the first and second light restricting members/configurations are each 1.5 mm or smaller.

Abstract: An image information detecting apparatus comprises a light source comprising a light emitting surface, an image bearing member, a light receiving unit comprising a light receiving surface, an illumination optical system for causing the light emitting surface and the image bearing member to have a conjugate relationship and illuminating a pattern for detecting the overlap positional deviation with a beam; and a light receiving optical system for causing the image bearing member and the light receiving surface to have a conjugate relationship and guiding the beam for detecting the overlap positional deviation to the light receiving unit, wherein a straight line portion of a conjugate image of the light emitting surface on the image bearing member and a straight line portion of a conjugate image of the light receiving surface on the image bearing member are parallel with each other.

Abstract: In this toner concentration sensor, as the magnetic permeability of a two-component developer 3 containing toner and carrier in a two-component developing unit 1 has changed with changing TC ratio of the two-component developer, the oscillation frequency of a first oscillation circuit 20 having a detection coil 5 changes, on the other hand the oscillation frequency of a second oscillation circuit 30 having a reference coil 6 does not change. While, changes in temperature conditions cause the oscillation frequency of the second oscillation circuit to change in the same way as the oscillation frequency of the first oscillation circuit. Therefore, utilizing a difference between the oscillation frequencies of the first and second oscillation circuits makes it possible to cancel out changes in the temperature conditions so that a value corresponding to only the magnetic permeability of the two-component developer can be obtained.

Abstract: An image forming apparatus includes an image bearing member, a detector that detects a density of developer on the image bearing member, a support member supported in the image forming apparatus and removably supporting the detector, a separator disposed with a space from the detector, a first connected unit disposed on the support member between the separator and detector, a second connected unit disposed on the support member on an opposite side of the detector from the first connected unit, a fixing member including a first connecting unit that passes through the space and is supported by the first connected unit and a second connecting unit supported by the second connected unit, where the fixing member fixes the detector to the support member, and a disengagement restricting unit disposed on an opposite side of the detector from the separator so as to be adjacent to the second connecting unit.

Abstract: A photosensor includes a light emitting element to emit light to a target object, a light receiving element to receive the light emitted from the light emitting element and reflected by the target object, and a circuit board on which the light emitting element and the light receiving element are mounted, including at least one protrusion thereon. The light emitting element and the light receiving element each have a terminal. The at least one protrusion is configured to support one of the light emitting element and the light receiving element in a contact manner in a state that the terminal is electrically connected to the circuit board.

Abstract: An optical sensor unit includes: a light-emitting device; a light-receiving device that receives light which is emitted from the light-emitting device and reflected from an object to be detected, and outputs an output value in accordance with the light; a shutter member that openably and closably covers an incident/exit plane having an exit part where light of the light-emitting device is emitted to the object to be detected and an incident part where light reflected from the object to be detected enters, and has a facing surface facing the incident/exit plane that is an inclined surface inclined to the incident/exit plane; and a corrector that corrects an output value of the light-receiving device when receiving light reflected from the object to be detected, based on an output value of the light-receiving device obtained by emitting light to the inclined surface of the shutter member.

Abstract: In an embodiment, a diffuse reflection output conversion method is executed in an apparatus detecting a plurality of gradation patterns. The apparatus includes a light emitter and light receiver, and detects specular reflection and diffuse reflection simultaneously. A region before specular reflection saturation is a region where the specular reflection component decreases and saturates at minimum level. A diffuse reflection detector is calibrated by: obtaining a diffuse reflection output resulting from an amount of attached powder at a border between the region before specular reflection saturation and the region after specular reflection saturation; calculating a ratio between the diffuse reflection output and a reference diffuse reflection output calculated in advance as a calibration coefficient; and multiplying a diffuse reflection output obtained from the gradation patterns by the calibration coefficient calculated at the calculating.

Abstract: An image forming apparatus includes a sensor having a light emitting section for irradiating a detection area and a light receiving section for outputting a light sensitive signal indicative of the amount of the light received from the detection area. A sensor adjustment section adjusts the sensitivity of the sensor by varying the set value of an adjustable characteristic value associated with the sensitivity, based on explorative measurement of the adjustable characteristic value corresponding to a predetermined reference level of the light sensitive signal. If an estimation section estimates that the amount of a leakage current generated on the light receiving section is larger than a reference amount, a mitigation section mitigates the influence of the leakage current on the explorative measurement, by at least one of adjustment of the light receiving section for reduction of the leakage current and modification of the predetermined reference level.

Abstract: A toner amount measuring unit irradiates a toner image formed on an image carrying member with light, and an image capturing unit captures an image of a reflected waveform according to light reflected by the toner image. Then, an amount of applied toner is calculated based on the peak position or peak height of the reflected waveform in accordance with information associated with the density of the toner image to be formed.

Abstract: A toner density sensor has a light emitting unit that emits light to detect toner density, a light receiving unit that receives the light emitted from the light emitting unit and reflected from a detection target, and a board on which the light emitting unit and the light receiving unit are surface-mounted. A penetration space that penetrates the board in a thickness direction is formed in at least one of portions in which the light emitting unit and the light receiving unit are attached to the board.

Abstract: The change in an output voltage when a control voltage is changed is calculated, and the change in the control voltage divided by the calculated change in the output voltage is defined as a sensitivity coefficient. The sensitivity coefficient is recalculated for each predetermined time interval or whenever a predetermined condition is satisfied, and the control voltage is corrected based on the recalculated sensitivity coefficient. Example of the predetermined condition include the time of start-up of the apparatus, the time at which the accumulated number of printed sheets reaches a predetermined number, and the time of carrying out process control.

Abstract: A printer apparatus 100 includes a reflection densitometer 102 comprising an optical sensor 104 that detects light reflected from each color patch on each page in a sequence of measurements, and a processor 106 which is coupled to the optical sensor 104 and manages the calibration and measurement operations. The processor 106 determines the magnitude of a gloss component of the illumination and compares the gloss component magnitude from a plurality of measurements at selected dissimilar ink coverage.

Abstract: An image forming apparatus to detect the toner density of a patch pattern formed on a photosensitive medium or a transfer belt without a deviation in light intensity includes a density sensor including a light emitter to scan light onto at least one patch pattern formed as a toner image and a light receiver to receive light reflected from the at least one patch pattern and convert the received light to an electrical signal, a switch to turn on or off the light emitter, and a controller to maintain light intensity of the light emitter within a reference range by controlling on-time and off-time of the switch.

Abstract: A toner amount measuring unit irradiates a toner image formed on an image carrying member with light, and an image capturing unit captures an image of a reflected waveform according to light reflected by the toner image. Then, an amount of applied toner is calculated based on the peak position or peak height of the reflected waveform in accordance with information associated with the density of the toner image to be formed.

Abstract: An image forming device has a conveying member, a light source, a photo-sensor, a shutter member, a shutter driving unit, a reflecting member and a judging member. The shutter member located between the photo-sensor and the conveying member is moved between a close position and an open position. The reflecting member provided on shutter member reflects light emitted by the light source when the shutter member entirely or partially shields the light emitted by the light source and directed toward the conveying member, and an intensity of light reflected by the reflecting member and detected by the photo-sensor varying depending on a position of the shutter member. The judging member judges whether the shutter member is located at the close position or the open position and whether the conveying member is present or absent based on the intensity of the light detected by the photo-sensor.

Abstract: An image forming apparatus includes image forming sections that forms images of different colors, respectively, a correction image formation controlling section that forms correction images of the respective colors, a density sensor that detects a density of each of the correction images in synchronization with passage of each correction image on an image carrying body, a detecting section that detects a position and the density of each of the correction images, based on a binary signal of a density detection output of each of the correction images, a density correction controlling section that corrects and controls an image density of the color, based on the detected density of each of the correction images, and a color deviation correction controlling section that corrects and controls the color deviation, based on the detected position of each of the correction images.

Abstract: An image forming apparatus includes a sensor member having first and second ends opposite to each other in a longitudinal direction of the sensor member and supported by support structures consisting of the first and second ends, and first and second support portions supporting the first and second ends; a first support structure including a first protruding portion fitted on a first recess portion supporting the first protruding portion; and a second support structure including a second protruding portion fitted on a second recess portion supporting the second protruding portion. The second protruding portion has first and second cylinder portions extending in a longitudinal direction of the second protruding portion. The second recess portion has an insertion portion allowing the second protruding portion to be inserted, a pass portion allowing the first cylinder portion to pass therethrough, and a positioning portion fitted on the second cylinder portion.

Abstract: A detection device includes: an imaging unit that forms an image of an incident beam on an image detection unit; an emission unit that includes a guided portion that is guided to a guiding portion provided at the imaging unit and guiding an attachment-detachment operation of the guided portion, a positioned portion that is positioned in a positioning portion provided at the imaging unit, and an emission member that emits a beam toward a direction of a transportation path such that a beam reflected from the medium is incident to the imaging unit; and a setting unit that includes a positioned portion that is positioned in a positioning portion provided at the emission unit when a drawing unit is pressure-inserted into the image forming apparatus and a setting surface that sets a position on the medium at which the beam is reflected.

Abstract: An image forming apparatus includes an image carrying member, an image forming mechanism, an optical sensor, and a controller. The image forming mechanism performs an image forming operation for forming a reference toner image on the image carrying member under a specific setting associated with the image forming mechanism. The optical sensor is arranged in a vicinity to the image carrying member. The controller performs an optical toner test for checking, by using the optical sensor, optical characteristics of the reference toner image formed on the image carrying member and to adjust the specific setting based on a result of the optical toner test.

Abstract: A method and system for improved image quality using an image quality matching method is used to match the optical density of single prints produced on multiple print engines by first sensing the optical density of a first image produced on a first print engine and then sensing the optical density of a second image produced on a second print engine before comparing the optical densities and determining if they are substantially equal. If they are not equal set points and exposures are adjusted on one or both print engines until the differences between the optical densities is less than 0.05, preferably 0.03. The density is changed by adjusting the initial voltage on the primary imaging member of at least one print engine and/or by adjusting the exposure of the primary imaging member of at least one print engine.

Abstract: An image forming apparatus includes a toner carrier, a toner image forming unit, and a toner concentration sensor. The toner carrier includes a transparent film. The toner image forming unit forms a toner image onto the toner carrier. The toner concentration sensor senses the concentration of toner on the toner carrier. The toner concentration sensor includes first and second light emitting elements and a light receiving element. The light emitting elements each radiate light directly or indirectly to the toner carrier. The light receiving element receives reflecting light originating from the light emitting elements. The first light emitting element radiates light having a wavelength of a predetermined reflectance resulting from direct radiation to the toner carrier. The second light emitting element radiates light having a wavelength that causes a lower reflectance resulting from direct radiation to the toner carrier than a reflectance resulting from radiation to the toner.

Abstract: An image forming apparatus includes an image forming unit configured to form a plurality of toner images on an image carrier, an optical detector configured to detect reflection light from the toner image, and dedicated to detect infrared rays and near-infrared rays, and a controller configured to perform a predetermined control using a detection results of the optical detector. Gradation pattern that is comprised of a plurality of toner patches formed in the image forming unit with an image forming condition to have different adhesive amounts, and is formed of at least two colors, and detection values detected by the optical detector are used for the predetermined control.

Abstract: In an embodiment of the present invention, an image forming apparatus includes a transfer belt that primarily transfers a toner image formed on a photosensitive drum; a secondary transfer unit including a transfer mechanism portion that secondarily transfers the primarily transferred toner image to a paper; an optical sensor that detects a reference toner image on the transfer belt; and a shutter that protects a detection face of the optical sensor, wherein a separation/contact mechanism portion disposed so as to be brought into contact with both of the shutter and the secondary transfer unit is provided, and the separation/contact mechanism portion allows the shutter to move so as to open and allows the secondary transfer unit to move so as to separate from the transfer belt when the reference toner image is detected by the optical sensor, and allows the shutter to move so as to separate from the transfer belt when the secondary transfer unit is drawn out from an apparatus main body.

Abstract: An image forming apparatus includes an image bearing member, a toner image forming unit, a sensor, and a control unit. The toner image forming unit is configured to form a toner image on the image bearing member. The sensor includes a light-emitting unit for emitting light, a light-receiving unit for receiving reflected light, an electrical circuit board in which the light-emitting unit is attached, and a frame supporting the electrical circuit board with the electrical circuit board bonded with three supporting portions. The sensor is configured to detect the toner image formed on the image bearing member. The control unit is configured to control a toner image forming condition of the toner image forming unit according to an output of the sensor.

Abstract: Toner images of reference patterns having different resolutions are formed on an image carrier, image densities of the toner images of reference patterns are detected by a density sensor, and an output of the density sensor, when the detected densities equate among the reference patterns having different resolutions formed with the same image forming condition, is memorized as a reference value for calibrating the output the density sensor.

Abstract: An image forming apparatus includes a controller for detecting the opening and closing of a shutter from the output from an optical sensor and controlling the opening and closing operation of the shutter based on the detected result. The controller determines that if the optical sensor is turned “ON” within a predetermined period of time from when the shutter begins opening, the operation of the shutter from the closed state to the open state is correctly detected. When no reflected light is detected by the optical sensor even after a predetermined time has elapsed, the controller determines that an anomaly has occurred and closes the shutter and repeat another detecting process.

Abstract: An image forming apparatus includes an image bearing member for bearing a toner image; toner image forming means for forming a toner image on the image bearing member; a detecting member for directing light to an object and for detecting the light reflected by the object; a controller for controlling a toner image forming condition of the toner image forming means in accordance with an output of the detecting member with respect to the toner image formed on the image bearing member and an output of the detecting member with respect to the image bearing member; a cleaning member, in contact to the image bearing member, for cleaning the image bearing member; an executing portion for executing, when the output with respect to the image bearing member reaches a reference level, an operation in a cleaning mode in which the cleaning member cleans the image bearing member; and a change portion for changing the reference level in accordance with a use amount of the image bearing member.

Abstract: A density sensor detects a density of a subject according to a variation in received light. The density sensor comprises a base plate, a light emitting element irradiating a subject with light, the light receiving element receiving light reflected by the subject, lead terminals connected at one end with bottoms of the light emitting and receiving elements, respectively, and electrically connected at the other end with the base plate, and a package containing the light emitting and receiving elements and supported by the base plate, wherein at least one of the lead terminals is configured to be inclined from a halfway position so as to reflect light from the light emitting element in a direction away from the bottom of the light receiving element.

Abstract: An optical sensor attached to an apparatus includes a substrate and a light emitting element mounted on a first surface of the substrate. The light emitting element emits a light to a detection object in parallel to the substrate. A light receiving element is mounted on the first surface of the substrate. The light receiving element receives a regular reflection light reflected by the detection object. The said first surface serves as a positioning reference for positioning the optical sensor on an optical sensor mounting member provided in the apparatus.

Abstract: Disclosed is an evaluation device of an optical writing device, comprising: the optical writing device; a light reception section; a drive section; and a control section to light each light emitting element in a previously set lighting pattern based on a light amount; to drive the drive section to move the light reception section to a position opposite to the light emitting element to be lit; to calculate characteristic data based on a light amount value of the light received by the light reception section; to calculate a first calculation value based on the characteristic data for each light emitting element; to calculate a second calculation value different from the first calculation value based on the characteristic data; to calculate a third calculation value based on the first calculation value and the second calculation value; and to instruct the display section to display the third calculation value.

Abstract: An electrophotographic image formation device comprises an image transfer unit (including an image transfer member) attached to a main body in a detachable manner, a density detecting unit including a detector unit and thereby detecting density of a developing agent transferred to the image transfer member, a protective cover which protects the density detecting unit not detecting the density by covering the detector unit, first and second reflecting parts (differing in reflectivity) formed in a part of the protective cover facing the detector unit, and a shifting unit which places the protective cover at a first position (with the first reflecting part facing the detector unit) when the image transfer unit has been attached to the main body while placing the protective cover at a second position (with the second reflecting part facing the detector unit) when the image transfer unit has not been attached to the main body.

Abstract: An image forming apparatus to detect the toner density of a patch pattern formed on a photosensitive medium or a transfer belt without a deviation in light intensity includes a density sensor including a light emitter to scan light onto at least one patch pattern formed as a toner image and a light receiver to receive light reflected from the at least one patch pattern and convert the received light to an electrical signal, a switch to turn on or off the light emitter, and a controller to maintain light intensity of the light emitter within a reference range by controlling on-time and off-time of the switch.

Abstract: An image processing apparatus, according to the present invention can include a forming portion capable of forming a mark on a bearing member, a light projecting portion capable of irradiating a light onto the bearing member, a light receiving portion capable of receiving a reflection light from the bearing member and from the mark, and outputs a received light signal in accordance with the received light amount, a judging portion capable of judging the existence or non-existence of a mark on the bearing member based on the received light signal, an evaluating portion capable of evaluating a reflection state of the bearing member and an adjusting portion capable of adjusting a light receiving sensitivity of the light receiving portion at a time of a judgment by the judging portion, in accordance with an evaluation of the evaluating portion.

Abstract: An optical sensor includes: a light-emitting unit; a light-receiving unit that receives light radiated from the light-emitting unit and reflected from a detection target and that outputs an output value in response to the light received; and a correcting unit that corrects the output value of the light-receiving unit when receiving the light reflected from the detection target based on the output value of the light-receiving unit obtained by irradiating a detection area of the optical sensor with light without any light reflective objects being present in the detection area.

Abstract: An image output controller is capable of directly or indirectly controlling a printer printing a color chart and a color measuring apparatus carrying out color measurement for the color chart. When color authentication is executed for an optionally set image, a process is carried out in relation to user's setting or automatic optimization including at least one of a printing position of the color chart, a layout of the color chart and a color value of the color chart. The printer is controlled according to a printing condition based on the user's setting or the automatic optimization so that the color chart is printed on a sheet of predetermined printing paper. The color measuring apparatus is controlled so as to carry out color measurement for the printed color chart.

Abstract: A reflective optical sensor detects a position and/or a toner density of the toner pattern. The reflective optical sensor includes an illuminating system that has at least three light-emitting units, a light-receiving system that has at least three light-receiving units and receives light output from the illuminating system and reflected by the toner pattern, and an illuminating optical system that includes at least three illuminating condenser lenses individually corresponding to the at least three light-emitting units and that guides the light output from the illuminating system to the toner pattern. The at least three light-emitting units and the at least three light-receiving units are both arranged in equal distance with respect to one direction. Optical axes of the at least three illuminating condenser lenses are off-center in parallel to an axis passing through a center of and perpendicular to the corresponding light-emitting unit.

Abstract: A reflective optical sensor includes at least three light-emitting elements; a lighting optical system that guides light emitted from the light-emitting elements to a toner pattern; and at least three light-receiving elements that receive the beams of light reflected by the toner pattern. The lighting optical system has a lateral magnification m that satisfies m?P/S, where S is the size of the light-emitting elements and P is the arrangement pitch of the light-emitting elements.

Abstract: A light amount measuring device, according to the present invention can include, a light-receiving sensor capable of outputting a voltage corresponding to an amount of incident light, an A/D converting portion capable of converting an input voltage into a digital value, a light amount calculating portion capable of calculating the amount of light incident on the light-receiving sensor on the basis of the digital value obtained by conversion by the A/D converting portion, a resistor connected between the A/D converting portion and the light-receiving sensor, a zener diode has one end connected between the A/D converting portion and the resistor, wherein the zener diode is capable of allowing a breakdown current flow from the one end to another end if an output voltage from the light-receiving sensor is not less than a predetermined value.

Abstract: Disclosed is an image forming apparatus, a sheet finisher and an image forming system; each of them including: a display for displaying a work item for a maintenance in the form of a guidance display; a detection section for detecting whether the work item is executed or not; an energization controller for supplying/blocking power supply to electric components to be maintained; a connection judging section for judging whether the electric components are electrically connected with the power supply or not; and a controller for controlling the display to switch displays of the work item and for controlling the energization controller, in accordance with a detection result of the detection section; wherein the controller causes the display to display an alarm and a guidance display of a corresponding work, according to a judgment of the connection judging section.