JP5939391B2 - Endless moving member detection apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an endless moving member detection device and an image forming apparatus including the endless moving member detection device.

  An electrophotographic color image forming apparatus such as a copying machine or a printer has four photoconductors corresponding to toners of four colors (yellow, cyan, magenta, black) in order to meet the recent demand for higher speed. A so-called tandem system in which (latent image carriers) are arranged side by side has become mainstream.

  In such a tandem system, a direct transfer system in which each color toner image is sequentially transferred onto a sheet-like recording medium conveyed by a transfer belt as an endless moving member, or each color photoconductor. From the intermediate transfer system in which each color toner image is sequentially transferred onto an intermediate transfer belt as an endless moving member, and then a full color toner image is collectively transferred onto the sheet-like recording medium from the intermediate transfer belt. Each color toner image developed on each color photoconductor is transferred onto a sheet-like recording medium (eg, paper, postcard, OHP (Overhead projector) sheet, etc.).

  In the direct transfer method, color misregistration occurs unless the conveyance belt that conveys the sheet-like recording medium is driven with high accuracy. In the intermediate transfer method, color misregistration occurs unless the intermediate transfer belt is driven with high accuracy. Resulting in.

  For this reason, in order to drive the intermediate transfer belt with high accuracy, the speckle pattern of the laser beam that is scanned on the intermediate transfer belt is received by a solid-state image sensor such as a CMOS image sensor (Complementary Metal Oxide Semiconductor Image Sensor). At the same time, the chronological change of the speckle pattern on the intermediate transfer belt is correlated to calculate the XY direction of the intermediate transfer belt (the X direction is the transport direction of the intermediate transfer belt, and the Y direction is a direction perpendicular to the X direction). A displacement detection device that detects a displacement in a so-called in-plane direction is known (for example, see Patent Document 1).

  In order to prevent meandering of the intermediate transfer belt, a sensor such as a photo interrupter provided with a light emitting portion and a light receiving portion facing each other is disposed at an end portion parallel to the conveyance direction of the intermediate transfer belt, and the sensor There is known a meandering correction device that drives a meandering correction roller based on an end detection signal from the sensor to correct meandering of an intermediate transfer belt (see, for example, Patent Document 2).

  However, in the conventional displacement detection device disclosed in Patent Document 1, the vector in the orthogonal direction (Y direction) with respect to the conveyance direction (X direction) of the intermediate belt is also changed by the change in the tension posture of the intermediate transfer belt. Therefore, the detected vector component in the Y direction is a combination of the component in which the intermediate transfer belt approaches the Y direction and the angle at which the intermediate transfer belt is stretched around the roller. Detects the vector where the intermediate transfer belt moves in the Y direction even if the intermediate transfer belt moves around without moving in the Y direction when the angle of the belt stretched around the roller is not right angle There was a problem of doing.

  For this reason, if the position of the intermediate transfer belt that moves around without moving in the Y direction is adjusted based on the detected vector that moves in the Y direction, the toner image transferred onto the intermediate transfer belt is adjusted. There is a possibility that the transfer position of the image is shifted.

  In addition, when the mounting angle of the solid-state imaging device is tilted from the original angle, the intermediate transfer belt detects a vector that approaches the Y direction, so that erroneous control is performed, and the intermediate transfer belt falls off the roller. Or it may be too close to the Y direction and damage surrounding parts.

  Further, in the conventional meandering correction device disclosed in Patent Document 2, the photointerrupter is affected by the orthogonality of the end of the intermediate transfer belt, and the received light amount of the phototransistor constituting the photointerceptor of the photointerrupter is increased or decreased. Accordingly, the end of the intermediate transfer belt is detected, so that there is a limit in detecting the amount of displacement of the intermediate transfer belt in the Y direction with high definition.

  Further, there is uneven cutting at the end (belt edge) of the intermediate transfer belt, and in order to accurately detect the end, the profile of the end is stored, or for one rotation of the intermediate transfer belt. It is necessary to remove the components such as the cutting unevenness by using the average value of the above, and there is a problem that the real-time property is lost.

  For this reason, in the image forming apparatus in which the conventional displacement detection device shown in Patent Document 1 or the conventional meandering correction device shown in Patent Document 2 is mounted, image position accuracy and position There is a limit to the improvement in alignment accuracy, and there is a limit to high-quality and high-quality image formation.

  The present invention aims to solve this problem. That is, the present invention can reduce the influence of the change in the stretching posture of the endless moving member and can reduce the influence of the change in the mounting posture of the solid-state imaging device, and the amount of displacement of the endless moving member can be high-definition. It is an object of the present invention to provide an endless moving member detection device capable of detecting, and an object of the present invention is to provide an image forming apparatus capable of forming a high-quality image with high accuracy.

  In order to solve the above problems and achieve the object, an endless moving member detection apparatus of the present invention includes a light source for irradiating coherent light to a circulating endless moving member, and a solid capable of acquiring a two-dimensional image. An imaging device, an imaging optical system that forms an image on the solid-state imaging device with a speckle pattern when coherent light is applied to the endless moving member from the light source, and constant along with the movement of the endless moving member Image pattern acquisition means for acquiring the speckle pattern imaged on the solid-state image sensor at time intervals as an image pattern, and the speed of the endless moving member by calculating the image pattern acquired by the image pattern acquisition means An endless moving member detecting device having a speed calculating means for calculating a home position corresponding to a home position of the endless moving member. A home position signal generating means for generating a transition signal, a timing generating means for generating an acquisition timing for acquiring an image pattern by the solid-state imaging device based on a home position signal from the home position signal generating means, and the image Orthogonal movement calculating means for calculating a movement amount in a direction orthogonal to the conveying direction of the endless moving member by calculating the image pattern acquired by the pattern acquisition means, and acquiring from the timing generating means The image information of the image pattern at the home position of the endless moving member acquired based on the timing is stored in the storage means, and the orthogonal movement calculation means includes the image information of the image pattern stored in the storage means, Acquired based on the acquisition timing from the timing generation means It is characterized by calculating the movement amount in the direction which is perpendicular to the conveying direction of the image information of the image pattern in the home position of the endless moving member, by comparing the endless moving member.

  The moving member detection apparatus of the present invention causes the orthogonal movement calculation means to compare and calculate the image information of the image pattern stored in the storage means and the image information of the image pattern acquired based on the acquisition timing from the timing generation means. Even if the mounting posture of the solid-state imaging device is tilted by calculating the movement amount (shift amount) in the direction (shift direction) orthogonal to the transport direction of the endless move member, the endless move member When no deviation occurs, a change in the deviation direction of the speckle pattern is not detected, so that the position of the endless moving member can be prevented from being unnecessarily adjusted.

  In addition, when the mounting posture of the solid-state imaging device is inclined and the endless moving member is shifted, the change in the direction of the speckle pattern can be detected, so the position of the endless moving member is adjusted. can do.

  If the endless moving member is tilted and the endless moving member is not displaced, a change in the direction of the speckle pattern is not detected, and the endless moving member is not stretched. When the position of the endless moving member is tilted and the endless moving member is deviated, a change in the direction of the speckle pattern can be detected, so that the position of the endless moving member can be adjusted appropriately. it can.

  In other words, by comparing and calculating the same location with respect to the conveying direction of the endless moving member, it is influenced by both the inclination of the stretching posture of the endless moving member and the inclination of the mounting posture of the solid-state imaging device. Therefore, it is possible to accurately detect the movement of the speckle pattern in the belt shift direction and perform stable shift control.

  Further, the speckle pattern is sufficiently fine, and the shift amount in the shift direction of the endless moving member is detected from the displacement of the speckle pattern, so that the shift amount of the endless moving member can be detected with high definition. .

  Therefore, the endless moving member can be prevented from dropping or damaged due to erroneous detection of the deviation amount of the endless moving member, and the meandering of the endless moving member can be controlled with high accuracy.

  In this way, the endless moving member can be prevented from falling off or damaged, and the meandering of the endless moving member can be controlled with high accuracy. Therefore, the transfer belt or the intermediate transfer belt as the endless moving member is provided. In the image forming apparatus, a high-quality image with high image position accuracy and alignment accuracy can be formed.

1 is a schematic diagram of an image forming apparatus according to a first embodiment of the present invention. It is a figure for demonstrating the structure of the endless moving member detection apparatus provided in the image forming apparatus shown in FIG. It is a schematic diagram of the circuit of the speed calculation means of the endless moving member detection apparatus shown in FIG. It is explanatory drawing for demonstrating the structure of a home position signal production | generation means. (A) is a top view, (B) is a schematic diagram of a speckle pattern. It is explanatory drawing for demonstrating the home position mark of a home position signal production | generation means. (A) is a partially enlarged view, and (B) is a schematic diagram of a home position mark imaged by an area sensor. It is a flowchart which shows the process sequence which performs a correlation calculation process in the endless moving member detection apparatus shown in FIG. It is a figure which shows the image pattern imaged by the area sensor. (A) is a figure which shows the image pattern of the 1st rotation, (B) is a figure which shows the image pattern of the 2nd rotation. It is a figure which shows the conveyance direction area utilized by a speed calculation means, and the shift direction area utilized by an orthogonal movement calculation means in the image pattern imaged by the area sensor. It is a timing chart of the home position sensor and image acquisition clock of the endless moving member detection apparatus concerning the 3rd Embodiment of this invention. It is a figure which shows the image pattern imaged by the area sensor of the endless moving member detection apparatus concerning the 3rd Embodiment of this invention. (A) is a figure which shows the image pattern of the 1st sample, (B) is a figure which shows the image pattern of the 2nd sample. It is a figure showing integration | accumulation of the shift component by the sampling in a fixed time period. It is a figure for demonstrating correction | amendment of the integration | accumulation result of a shift component. (A) is a figure before correction | amendment, (B) is a figure after correction | amendment. It is a figure which shows the detection area on the intermediate transfer belt of the endless moving member detection apparatus concerning the 4th Embodiment of this invention. (A) is a plan view and (B) is a diagram showing an image pattern corresponding to image information stored in a memory. It is the schematic of the image forming apparatus concerning the 5th Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The embodiments of the present invention described below are merely representative embodiments of the present invention, and the present invention is not limited to the embodiments. Therefore, the present invention can be implemented with various modifications without departing from the gist of the present invention, that is, those that can be easily assumed by those skilled in the art, substantially the same, and so-called equivalent ranges.

(First embodiment)
FIG. 1 is a schematic diagram of an image forming apparatus 30 according to the first embodiment of the present invention. FIG. 2 is a diagram for explaining the configuration of the endless moving member detection device 1 provided in the image forming apparatus 30. FIG. 3 is a schematic diagram of a circuit of the speed calculation unit 12. 4 and 5 are schematic views of the intermediate transfer belt 2.

  The image forming apparatus 30 according to the first embodiment of the present invention is a copying machine, a printer, a facsimile, or a complex machine thereof, and is, for example, a tandem type full-color image forming apparatus. The image forming apparatus 30 records a toner image on a sheet-like recording medium such as paper, recording paper, transfer paper, or an OHP (Overhead projector) sheet.

  As shown in FIG. 1, the image forming apparatus 30 includes an optical scanning device 31 as a latent image forming unit, photosensitive drums 33Y to 33K as a latent image carrier, and an intermediate transfer belt 2 as an endless moving member. Primary transfer rollers 38Y to 38K, a secondary transfer roller 43, and a fixing device 47.

  The optical scanning device 31 receives the reflected light reflected from the document on the contact glass (not shown) and converts the electrical signal from the image sensor into an electrical signal, and the image processing means processes the electrical signal. A laser light emitting device that performs line scanning of laser light in the main scanning direction based on image information, and an fθ lens that collects the laser light from the laser light emitting device and corrects the scanning speed in the main scanning direction to be constant. And a reflecting mirror that irradiates the respective photosensitive drums 33Y to 33K with laser light whose scanning speed in the main scanning direction is constant by the fθ lens.

  The laser light emitting device includes a light source composed of a semiconductor laser that emits laser light, and an optical deflector that deflects the laser light in the main scanning direction. The light source is provided with a semiconductor laser corresponding to each of yellow, cyan, magenta, and black, which are color separation components of a color image.

  As the optical deflector, for example, a known one capable of deflecting laser light in the main scanning direction, such as a rotating polygon mirror (polygon mirror) or a galvanometer mirror, can be adopted.

  The photosensitive drum 33Y includes a charging unit 35Y as a charging unit corresponding to yellow toner, a developing unit 36Y as a developing unit, and a cleaning device 37Y. The photosensitive drum 33C is a charging unit 35C corresponding to cyan toner. A developing device 36C and a cleaning device 37C. The photosensitive drum 33M includes a charging device 35M corresponding to magenta toner, a developing device 36M, and a cleaning device 37M. The photosensitive drum 33K corresponds to black toner. The charging device 35K, the developing device 36K, and the cleaning device 37K are provided.

  The photosensitive drums 33Y to 33K, the chargers 35Y to 35K, the developing devices 36Y to 36K, and the cleaning devices 37Y to 37K constitute a process unit that is detachably attached to the image forming apparatus 30.

  The photoconductor drums 33Y to 33K are made of, for example, a cylindrical aluminum base tube, and an organic photoconductor layer is provided on the outer peripheral surface of the aluminum base tube. On the photosensitive drums 33Y to 33K, electrostatic latent images are formed on the organic photosensitive layer by the laser beam scanned in accordance with the image forming signal, and toner as an unfixed image is formed by the developer of the developing units 36Y to 36K. An image is formed.

  The organic photoreceptor layer includes, for example, an undercoat layer coated on an outer peripheral surface of an aluminum base tube, a charge generation layer that generates both positive and negative charges by photoelectric conversion, and a positive charge generated in the charge generation layer. And a charge transport layer for neutralizing negative charges charged on the surface, and an overcoat layer for improving durability.

  The chargers 35Y to 35K are for uniformly charging the surfaces of the photosensitive drums 33Y to 33K. By applying a charging bias, the surfaces of the photosensitive drums 33Y to 33K are set to a desired polarity and a desired potential. A charging member for uniformly charging is provided. As the charging member, for example, a charging roller made of an elastic body, a scorotron charger having a wire electrode and a grid electrode, or the like can be used.

  The developing devices 36Y to 36K include a developer corresponding to each color, and a developing roller that is disposed to face the photosensitive drums 33Y to 33K and supplies toner onto the photosensitive drums 33Y to 33K.

  The developer 36Y contains a developer corresponding to yellow, which is a color separation component of a color image, and the developer 36C contains a developer, corresponding to cyan, which is a color separation component of a color image. The developer corresponding to magenta of the color separation component of the color image is accommodated, and the developer corresponding to black of the color separation component of the color image is accommodated in the developing device 36K.

  As the developer, for example, a two-component developer (including a case where an additive or the like is added) composed of a magnetic carrier and a nonmagnetic toner is used. The carrier and the toner are mixed in the casings of the developing units 36Y to 36K, so that the carrier is charged to the positive electrode and the toner is charged to the negative electrode. The carrier is formed, for example, by coating the surface of a fine powder such as iron or ferrite with an organic polymer.

  The toner includes, for example, transparent resin fine particles as an adhesive that is melted by heating, cyan (light blue) pigment, magenta (red purple) pigment, yellow (yellow) pigment, and black (black) pigment. Particles of any one of the above, fine particles of wax for suppressing the stickiness of the resin melted by heating, fine particles of a charge control agent for promoting frictional charging between the carrier and the toner, and adhesion between the particles And fine particles of an additive for suppressing the dispersion.

  As the developer, a magnetic toner can be used instead of the above-described configuration, and other known developers can be adopted.

  The developing roller includes a cylindrical magnet roller having a plurality of fixed magnetic poles, and a non-magnetic conductive cored bar that is externally attached to the magnet roller. The cored bar is made of, for example, a hollow aluminum base tube. In the developing roller, a region facing the photosensitive drums 33Y to 33K is a developing region.

  For this reason, the developing roller draws up the developer on the surface of the developing roller and rotates while being carried on the surface, and can carry the carried developer to the developing area facing the photosensitive drums 33Y to 33K.

  The developing roller is applied with a developing bias from a developing bias power source. For this reason, in the developing area, a potential difference is generated between the potential of the surface of the developing roller and the potential of the electrostatic latent image portion on the surface of the photosensitive drums 33Y to 33K, and the action of the developing electric field formed by this potential difference is caused. In response, the toner in the developer adheres to the electrostatic latent image.

  In this manner, by attaching toner from the developing roller to the electrostatic latent images on the photosensitive drums 33Y to 33K, the electrostatic latent images on the photosensitive drums 33Y to 33K become toner images as unfixed images.

  The cleaning devices 37Y to 37K are for removing residual transfer toner remaining on the surfaces of the photosensitive drums 33Y to 33K without being transferred onto the sheet-like recording medium from the surfaces of the photosensitive drums 33Y to 33K. The cleaning devices 37Y to 37K include blade members that scrape off and remove the transfer residual toner on the surfaces of the photosensitive drums 33Y to 33K.

  In addition to the untransferred toner, the blade member includes paper powder of the sheet-like recording medium, discharge products when the photosensitive drums 33Y to 33K are charged by the chargers 35Y to 35K, and additives added to the developer. Are removed from the photosensitive drums 33Y to 33K.

  Further, the blade member is made of, for example, a synthetic resin such as polyurethane resin, and is provided so as to be in a counter direction with respect to the rotation direction of the photosensitive drums 33Y to 33K, and the surface of the photosensitive drums 33Y to 33K. Is touching.

  The intermediate transfer belt 2 is an endless belt, and is stretched around a driving roller 39, a driven roller 40, and a tension roller 41. Further, the intermediate transfer belt 2 includes a belt cleaning device (not shown).

  The intermediate transfer belt 2 is a single layer or a plurality of layers such as, for example, vinylidene fluoride resin (PVDF resin), tetrafluoroethylene / ethylene copolymer resin (ETFE resin), polyimide resin (PI resin), polycarbonate resin (PC resin), or the like. A conductive material such as carbon black is dispersed.

  Further, a bias is applied to the intermediate transfer belt 2 with a polarity opposite to the polarity of the charge of the toner. For this reason, the toner image is transferred onto the intermediate transfer belt 2 by attracting the toner from the surface of the photosensitive drums 33Y to 33K to the intermediate transfer belt 2 side.

  The belt cleaning device includes a cleaning blade made of an elastic material such as urethane rubber that comes into contact with the intermediate transfer belt 2. The cleaning blade is detachably held by a swingable blade holder.

  The cleaning blade contacts the surface of the intermediate transfer belt 2 in a counter direction with respect to the circumferential direction of the intermediate transfer belt 2, and residual transfer toner on the surface of the intermediate transfer belt 2 is blocked and removed.

  As described above, since the cleaning blade comes into contact with the surface of the intermediate transfer belt 2, impurities such as paper powder of the sheet-like recording medium, additives added to the developer, and the like in addition to the transfer residual toner are present in the intermediate transfer belt. 2 is removed from the surface. Transfer residual toner or the like removed from the intermediate transfer belt 2 is collected by a toner collecting unit by a conveying unit provided in the belt cleaning device.

  The primary transfer rollers 38Y to 38K are disposed to face the photosensitive drums 33Y to 33K. The primary transfer rollers 38 </ b> Y to 38 </ b> K include a conductive shaft body and a conductive elastic body extrapolated to the conductive shaft body. A primary transfer nip is formed between the primary transfer rollers 38Y to 38K and the photosensitive drums 33Y to 33K.

  The primary transfer rollers 38Y to 38K are biased with a polarity opposite to the polarity of the charge on the photosensitive drums 33Y to 33K. Therefore, the toner is attracted from the surface of the photosensitive drums 33 </ b> Y to 33 </ b> K toward the intermediate transfer belt 2, and the toner image is primarily transferred onto the surface of the intermediate transfer belt 2.

  The conductive shaft is formed in a cylindrical bar shape, and is made of a metal such as stainless steel or aluminum. Note that the conductive shaft body may be made of a material having high mechanical strength and conductivity, such as carbon fiber, metal fiber, or a resin rod having a surface plated with metal.

  The conductive elastic body is formed in a cylindrical shape that is extrapolated to the conductive shaft body. For example, acrylonitrile butadiene rubber (NBR), ethylene / propylene / diene rubber (EPDM), chloroprene rubber (CR), etc. are carbon black. Sponge rubber to which a conductive material such as is added is used.

  The secondary transfer roller 43 is disposed to face the opposing roller 42 on which the intermediate transfer belt 2 is stretched, and a secondary transfer nip is formed between the secondary transfer roller 43 and the opposing roller 42. The secondary transfer roller 43 includes a conductive shaft and a conductive elastic body extrapolated to the conductive shaft.

  A bias is applied to the secondary transfer roller 43 with a polarity opposite to the polarity of the toner charge on the intermediate transfer belt 2. For this reason, the toner is attracted from the surface of the intermediate transfer belt 2 to the sheet-like recording medium side sandwiched by the secondary transfer nip, and the toner image is secondarily transferred onto the sheet-like recording medium.

  The conductive shaft body is made of a conductive metal similarly to the primary transfer rollers 38Y to 38K, and the conductive elastic body is made of a conductive sponge rubber like the primary transfer rollers 38Y to 38K. ing.

  Similar to the secondary transfer roller 43, the opposing roller 42 has a conductive shaft made of a conductive metal, and a conductive elastic made of a conductive sponge rubber that is extrapolated to the conductive shaft. And a body.

  The fixing device 47 heats and pressurizes a toner image as an unfixed image on a sheet-like recording medium and fixes it on the sheet-like recording medium. The fixing device 47 includes a fixing roller, and a pressure roller that is disposed to face the fixing roller and is pressed against the fixing roller to rotate the fixing roller. The fixing roller and the pressing roller are pressed against each other to form a fixing nip.

  The fixing roller is provided in the core metal, for example, a core metal formed in a cylindrical shape, an elastic layer that covers the outer peripheral surface of the core metal, a release layer that covers the outer peripheral surface of the elastic layer, and the like. And a heater as a heating source.

  The metal core is made of a known material such as a metal having high mechanical strength such as stainless steel or a carbon steel pipe for machine structure. The cored bar is formed wider (longer) than the sheet-like recording medium that passes through the fixing nip.

  The elastic layer is made of, for example, an elastic material such as silicone rubber, fluorine rubber, or foamable silicone rubber. The release layer is made of, for example, a fluororesin such as a tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin (PFA resin) or a tetrafluoroethylene resin (PTFE resin).

  As the heater, a known heating means such as a ceramic heater or a halogen heater is used. The output of the heater is controlled based on the surface temperature of the fixing roller detected by the temperature detection sensor, and the surface temperature of the fixing roller is held at a predetermined temperature.

  Similar to the fixing roller, the pressing roller includes a cored bar made of a metal having high mechanical strength, an elastic layer made of an elastic material, and a release layer made of a fluororesin. . The pressing roller is rotationally driven by a driving device such as a motor, and rotationally drives the fixing roller that is disposed opposite to and pressed against the pressing roller.

  As shown in FIG. 2, the image forming apparatus 30 configured as described above further includes an endless moving member detection device 1 for detecting the conveyance speed and the shift amount of the intermediate transfer belt 2 as an endless moving member. I have.

  The endless moving member detection apparatus 1 includes a light source 4 that irradiates the surface of the intermediate transfer belt 2 with a laser beam 5 as coherent light, an area sensor 7 that can acquire the surface of the intermediate transfer belt 2 as a two-dimensional image, Image pattern acquisition for acquiring a speckle pattern (see FIG. 4B) SP imaged on the area sensor 7 at regular time intervals as the intermediate transfer belt 2 moves as an image pattern (see FIG. 7A) P. Means 9; speed calculating means 12 for calculating the speed of the intermediate transfer belt 2 by calculating the image pattern P acquired by the image pattern acquiring means 9; and a home position corresponding to the home position of the intermediate transfer belt 2. Home position signal generating means for generating a signal, and based on a home position signal from the home position signal generating means A timing generation unit 11 that generates an acquisition timing for acquiring the image pattern P by the area sensor 7 and a conveyance direction of the intermediate transfer belt 2 by calculating the image pattern P acquired by the image pattern acquisition unit 9 (see FIG. 4 (A)) orthogonal movement calculation means 13 for calculating a movement amount (shift amount) in a direction orthogonal to X (shift direction Y), a controller 14 for controlling a series of means, and driving A drive unit (motor driver) 15 for driving both the motor 17 that rotationally drives the roller 39 and the steering adjustment device 19 that adjusts the steering of the driven roller 40 is provided.

  The light source 4 includes a semiconductor laser element that emits a laser beam 5 that is coherent light, and a collimator lens that makes the laser beam 5 emitted from the semiconductor laser element substantially parallel light. The semiconductor laser element is set to an output at which a speckle pattern (see FIG. 4B) SP is clearly formed on the intermediate transfer belt 2.

  The area sensor 7 uses a solid-state imaging device that acquires the surface of the intermediate transfer belt 2 as a two-dimensional image and a speckle pattern SP formed by the laser beam 5 irradiated on the surface of the intermediate transfer belt 2 as the solid-state imaging device. An imaging optical system (not shown) for forming an image.

  The area sensor 7 is arranged in parallel to the plane of the surface of the intermediate transfer belt 2. That is, the optical axis of the area sensor 7 is arranged so as to be orthogonal to the plane of the surface of the intermediate transfer belt 2. In addition, as shown in FIG. 4A, the area sensor 7 has a region where a part of a home position mark (see FIG. 4A) 3 described later can be detected as a detection region of the area sensor 7. As a detection area R0.

  As the solid-state imaging device, for example, a CCD image sensor (Charge Coupled Device Image Sensor) or a CMOS image sensor (Complementary Metal Oxide Semiconductor Image Sensor) is used. Note that the CMOS image sensor can be suitably used as a solid-state imaging device of the area sensor 7 because it can easily perform image processing since data in pixel units is obtained.

  As shown in FIG. 2, the image pattern acquisition means 9 is a speckle pattern (see FIG. 4B) SP that is imaged on the solid-state image sensor of the area sensor 7 at regular time intervals as the intermediate transfer belt 2 moves. An image is entered.

  Further, the image pattern acquisition unit 9 forms an area of the speckle pattern SP on the solid-state image pickup device of the area sensor 7 at a predetermined time interval (ie, exposure) as the intermediate transfer belt 2 moves. A control signal for controlling opening and closing of an electronic shutter of a shutter device (not shown) provided in the sensor 7 is output.

  Further, the image pattern acquisition unit 9 generates the speckle pattern SP on the intermediate transfer belt 2 according to the conveyance speed of the intermediate transfer belt 2, the sensitivity of the solid-state imaging device, the intensity of the laser beam 5 emitted from the light source 4, and the like. The exposure time is controlled so that it can be clearly read by the solid-state imaging device.

  Further, the image pattern acquisition means 9 uses the speckle pattern SP image acquired at regular time intervals as the intermediate transfer belt 2 moves as an image pattern (see FIG. 7A or FIG. 7B) P as a speed calculation means. 12 and the orthogonal movement calculation means 13.

  As shown in FIG. 3, the speed calculation unit 12 performs Fourier transform on an image pattern P that is a two-dimensional image output from the image pattern acquisition unit 9 at regular time intervals based on an acquisition timing from a timing generation unit 11 described later. The fast Fourier transform unit 21 and the result of transforming by the fast Fourier transform unit 21 are deleted from the low frequency region of the spatial frequency that is the background of the image that is not necessary for the correlation calculation of the speckle pattern SP. Memory 22 to be stored, conjugate complex number conversion unit 23 that reads the result stored in the memory 22, replaces the part deleted at the time of storage with 0, and converts it to a conjugate complex number, and results of the conjugate complex number conversion unit 23 The fast Fourier transform unit 21 changes the image pattern P having adjacent time intervals corresponding to the result of the conjugate complex number transform unit 23. A complex multiplication unit 24 that multiplies both the obtained results, an inverse fast Fourier transform unit 25 that performs inverse Fourier transform on the result of the complex multiplication unit 24, and a correlation peak obtained by performing subpixel processing on the result of the inverse fast Fourier transform unit 25. The peak position detection unit 26 for deriving and the correlation peak derived by the peak position detection unit 26 are vector-decomposed with respect to the transport direction (X direction) and the shift direction (Y direction) of the intermediate transfer belt 2 and the intermediate transfer belt 2 And a vector decomposing unit 27 for outputting the transport speed and displacement (skew).

  Further, the speed calculation means 12 is a home on the intermediate transfer belt 2 acquired based on the image information of the image pattern (see FIG. 7A) P1 stored in the memory 22 and the acquisition timing from the timing generation means. The moving speed in the transport direction Y of the intermediate transfer belt 2 is calculated by comparing the image information of the image pattern (see FIG. 7B) P2 at the position.

  Specifically, in this embodiment, when the home position signal generating means detects the home position mark 3 on the rotating intermediate transfer belt 2, the speed calculation means 12 rotates the intermediate transfer belt 2 at the first rotation. In some cases, the memory 22 stores the image information of the image pattern P1 of the first rotation (see FIG. 7A) P1, and the rotation of the intermediate transfer belt 2 is the second rotation (and the second and subsequent rotations). Sometimes, the correlation between the image information of the second rotation (and the second and subsequent rotations) image pattern (see FIG. 7B) P2 and the image information of the first rotation image pattern P1 stored in the memory 22 is calculated. To compare.

  Note that the image information of the image pattern P captured by the area sensor 7 is input to the speed calculation unit 12 at a different time interval different from the fixed time interval in the orthogonal movement calculation unit 13 to which the image information of the image pattern P is input. You may make it do.

  For example, the time interval of the speed calculation unit 12 is such that changes in the speckle pattern SP (displacement in the transport direction X and displacement in the shift direction Y) can be compared when correlation calculation is performed between image patterns P adjacent to each other in time interval. These time intervals are set to be relatively shorter than the time interval of the orthogonal movement calculating means 13.

  Further, the speed calculation means 12 is configured to sequentially compare the image information of the image patterns P adjacent to each other at time intervals, and obtain the positional deviation of the image pattern P as the correlation peak position.

  Furthermore, the speed calculation unit 12 reduces the storage capacity by deleting the low-frequency region of the spatial frequency that is the background of the image that is not necessary for the correlation calculation of the speckle pattern SP and storing it in the memory 22. In addition, the number of executions of Fourier transform can be reduced and the calculation efficiency can be improved as compared with the case of storing without deleting.

  As shown in FIG. 8, in the speed calculation unit 12, a rectangular conveyance direction that is long in the conveyance direction X so that image information on the image pattern P is sufficiently obtained in the conveyance direction X. Area H is processed as image information.

  That is, the speed calculation unit 12 can accurately calculate the transport speed by sufficiently securing the image information in the transport direction X, and reduce the load of the correlation calculation process by reducing the image information in the shift direction Y. It can be reduced.

  The memory (see FIG. 3) 22 of the speed calculation unit 12 can hold the storage of the image information of the image pattern (see FIG. 7A) P even if no power is supplied. A nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read-Only Memory) capable of selectively erasing a part and rewriting is used.

  Thus, since the non-volatile memory is used as the memory 22 of the speed calculation unit 12, for example, when the moving member detection device 1 is restarted, a step for storing the image information of the image pattern P is performed. This can be omitted, and the actual operation can be shifted to early.

  Note that information relating only to the conveyance speed of the intermediate transfer belt 2 is input from the vector decomposing unit (see FIG. 3) to a controller 14 (see FIG. 2) described later.

  As shown in FIGS. 2 and 4, the home position signal generation means includes a home position mark 3 provided on the surface of the intermediate transfer belt 2 and a home position sensor 10 that detects the home position mark 3. Yes.

  For example, as shown in FIG. 5A, the home position mark 3 includes a pair of extending portions 3a and 3b extending from the front side to the rear side in the transport direction X. The home position mark 3 is formed in a> shape of an inequality sign which is a mathematical symbol.

  The pair of extending portions 3a and 3b are formed so as to be gradually separated from the front side to the rear side in the transport direction X. The pair of extending portions 3a and 3b are formed on the intermediate transfer belt 2 by, for example, a method similar to a known registration mark.

  That is, as shown in FIG. 5A, the home position mark 3 is formed so that its shape changes in the direction Y of the intermediate transfer belt 2 in the detection area R of the area sensor 7. Yes.

  Specifically, as shown in FIGS. 5B to 5D, the pattern 6 of the home position mark 3 in the detection area R of the area sensor 7 is different from the shifting direction Y of the intermediate transfer belt 2. Is formed.

  Therefore, as shown in FIGS. 5B to 5D, a different pattern 6 of the home position mark 3 is obtained with respect to the direction Y of the intermediate transfer belt 2, so that pattern matching processing and edge detection are performed. The approximate position in the direction Y of the intermediate transfer belt 2 can be detected by processing or the like.

  The home position mark 3 is only required to have a shape in which a different pattern 6 of the home position mark 3 can be obtained with respect to the direction Y of the intermediate transfer belt 2, and is therefore limited to an> sign of an inequality sign which is a mathematical symbol. Without limitation, various shapes can be employed.

  The home position sensor 10 (see FIG. 2) includes a light emitting element such as a light emitting diode (LED) and a light projecting device that projects light onto the intermediate transfer belt 2, and a light receiving device such as a phototransistor. A so-called reflective photosensor is used, which is provided with a light receiver that is provided and receives light reflected from the intermediate transfer belt 2.

  The home position sensor 10 includes an amplifier unit that outputs a voltage corresponding to the amount of light received by the light receiving element of the light receiver, for example. The voltage output from the amplifier unit is the home position signal in the home position signal generating means.

  The home position signal output from the home position sensor 10 is received by timing generation means (see FIG. 2) 11 described later.

  Since the home position sensor 10 only needs to detect the home position mark 3 and output a home position signal to the timing generation unit 11, a known photo interrupter or the like can be employed.

  The timing generation unit 11 (see FIG. 2) includes, for example, an oscillation circuit unit that generates a periodic signal having a constant time period, a counter unit that counts the periodic signal of the oscillation circuit unit, and a reset that resets the count of the counter unit Generating timing at which the image sensor P is acquired at regular time intervals by the area sensor 7 based on the counter, the count of the counter unit, the home position signal, and the periodic signal And a section.

  Further, the timing generation unit 11 is configured to output the acquisition timing generated by the timing generation unit at regular time intervals so that the acquisition timing is input to the image pattern acquisition unit 9.

  Therefore, the acquisition timing output from the timing generation unit 11 is input to the image pattern acquisition unit 9 at regular time intervals, and a control signal for controlling opening and closing of the electronic shutter of the shutter device at regular time intervals is an image pattern. Output from the acquisition means 9.

  That is, based on the acquisition timing output from the timing generation unit 11 at regular time intervals, the image pattern acquisition unit 9 controls the opening and closing of the electronic shutter of the shutter device at regular time intervals. The image pattern P on the intermediate transfer belt 2 can be imaged at intervals.

  As shown in FIG. 3, the orthogonal movement calculation unit 13 is a two-dimensional image output from the image pattern acquisition unit 9 at regular time intervals based on the acquisition timing from the timing generation unit, similarly to the speed calculation unit 12. A fast Fourier transform unit 21 that Fourier transforms a certain image pattern P, and of the result of transforming by the fast Fourier transform unit 21, a low spatial frequency that is a background of an image that is not necessary for the correlation calculation of the speckle pattern SP. A memory 22 that deletes and stores a frequency region, a conjugate complex number conversion unit 23 that reads a result stored in the memory 22, replaces a portion deleted at the time of storage with 0, and converts the result to a conjugate complex number; The image pattern P adjacent to the result of the conjugate complex number conversion unit 23 and the time interval corresponding to the result of the conjugate complex number conversion unit 23 is the high speed A complex multiplication unit 24 that multiplies both the results converted by the Fourier transform unit 21, an inverse fast Fourier transform unit 25 that performs inverse Fourier transform on the result of the complex multiplication unit 24, and subtracts the result of the inverse fast Fourier transform unit 25. A peak position detection unit 26 that derives a correlation peak by pixel processing, and a correlation peak derived by the peak position detection unit 26 is subjected to vector decomposition with respect to the conveyance direction (X direction) and the shift direction (Y direction) of the intermediate transfer belt 2. And a vector decomposing unit 27 for outputting the conveyance speed and displacement (skew) of the intermediate transfer belt 2.

  Further, the orthogonal movement calculating means 13 is the intermediate transfer belt 2 acquired based on the image information of the image pattern (see FIG. 7A) P1 stored in the memory 22 and the acquisition timing from the timing generating means 11. Compared with the image information of the image pattern (see FIG. 7B) P2 at the upper home position, the movement amount (shift) in the direction (shift direction Y) orthogonal to the transport direction of the endless moving member (Quantity) is calculated.

  In this embodiment, when the home position signal generating means detects the home position mark 3 on the circulating intermediate transfer belt 2, the orthogonal movement calculating means 13 detects that the rotation of the intermediate transfer belt 2 is the first rotation. When the image information of the image pattern P1 of the first rotation (see FIG. 7A) P1 is stored in the memory 22 and the rotation of the intermediate transfer belt 2 is the second rotation (and after the second rotation), The image information of the second rotation (and the second and subsequent rotations) image pattern (see FIG. 7B) P2 and the image information of the first rotation image pattern P1 stored in the memory 22 are subjected to correlation calculation. It comes to compare.

  That is, the orthogonal movement calculation unit 13 obtains the image information of the image pattern P1 of the first rotation and the home position mark 3 on the rotating intermediate transfer belt 2 by the home position signal generation unit and detects the second rotation. It is configured to sequentially compare image information of subsequent image patterns P2. Further, the orthogonal movement calculation means 13 is configured to obtain the positional deviation of the image pattern P as the correlation peak position.

  Further, the orthogonal movement calculating means 13 reduces the storage capacity by deleting the low frequency region of the spatial frequency which is the background of the image which is not necessary for the correlation calculation of the speckle pattern SP and storing it in the memory 22. In addition, the number of executions of Fourier transform can be reduced and the calculation efficiency can be improved as compared with the case of storing without deleting.

  Further, as shown in FIG. 8, the orthogonal movement calculation means 13 has a rectangular shift that is long in the shift direction Y so that image information on the image pattern P can be sufficiently obtained with respect to the shift direction Y. The direction area V is processed as image information.

  That is, the orthogonal movement calculation means 13 can accurately calculate the displacement (skew) by sufficiently securing the image information in the shift direction Y, and can reduce the correlation information by reducing the image information in the transport direction X. The processing load can be reduced.

  For example, the memory 22 of the orthogonal movement calculation means 13 can hold the storage of the image information of the image pattern P1 of the first rotation without supplying power, and can selectively erase a part of the stored contents. A nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read-Only Memory) that can be written and rewritten is used.

  Thus, since the non-volatile memory is used as the memory 22 of the orthogonal movement calculation means 13, for example, when the moving member detection device 1 is restarted, the image information of the first rotation image pattern P1 is stored. The step for making it possible can be omitted, and the actual operation can be quickly shifted to.

  Note that information relating only to displacement (skew) of the intermediate transfer belt 2 is input from the vector decomposing unit 27 to the controller 14 described later.

  As shown in FIG. 2, for example, the controller 14 outputs a control signal for controlling the timing generation unit 11, receives information on the conveyance speed of the intermediate transfer belt 2 from the speed calculation unit 12, and calculates orthogonal movement. Information on displacement (skew) of the intermediate transfer belt 2 is inputted from the means 13 and an I / O circuit to which a control signal for controlling the drive unit 15 to be described later is outputted; information on the conveyance speed and displacement (skew) And an integrated circuit (IC) that determines control of both the timing generation unit 11 and the drive unit 15 based on the information of the row).

  For example, the drive unit 15 is a motor that drives the intermediate transfer belt 2 to rotate by a control signal output from the controller 14 based on information on the conveyance speed of the intermediate transfer belt 2 and information on displacement (skew). 17 is configured to output electric power for controlling the driving of the steering adjustment device 19 of the driven roller 40 on which the intermediate transfer belt 2 is stretched.

  Therefore, when the controller 14 determines that the intermediate transfer belt 2 is skewed (the inclination of the stretching posture) based on the displacement (skew) information from the orthogonal movement calculation means 13. Alternatively, if it is determined that the intermediate transfer belt 2 is displaced in the shifting direction Y, a control signal is output from the controller 14 as shown in FIG. A steering adjustment device 19 for adjusting the steering of the driven roller 40 to be mounted and a motor 17 for driving a driving roller 39 for rotating the intermediate transfer belt 2 are driven by the drive unit 15, and the intermediate transfer belt 2. The skew or displacement of the intermediate transfer belt 2 or the skew and displacement of the intermediate transfer belt 2 can be eliminated.

  As the steering adjustment device 19, a known device such as a steering mechanism or a steering device that can adjust the steering of the driven roller 40 with respect to the intermediate transfer belt 2 can be adopted. Further, the image pattern acquisition means 9, the speed calculation means 12, the orthogonal movement calculation means 13, the controller 14 and the drive unit 15 may be constituted by a one-chip microcomputer, for example.

  Next, the operation and processing in the image forming apparatus 30 according to the first embodiment of the present invention configured as described above will be described.

  As shown in FIG. 1, when the start key of the operation unit of the image forming apparatus 30 is pressed, the photosensitive drums 33Y to 33K corresponding to the respective colors of yellow, cyan, magenta, and black are rotationally driven. The surfaces of the body drums 33Y to 33K are uniformly charged to a predetermined polarity by the chargers 35Y to 35K.

  Further, the image information of the document on the contact glass is read by line scanning in the sub-scanning direction by an image reading device (not shown) and sent to the optical scanning device 31.

  The image information sent to the optical scanning device 31 is single-color image information obtained by separating the image information, which is a full-color image, into color information of yellow, cyan, magenta, and black by the image processing unit. Based on the image information, the laser beam is line-scanned in the main scanning direction, and the laser beams are irradiated onto the photosensitive drums 33Y to 33K corresponding to the respective colors.

  An electrostatic latent image corresponding to single-color image information of the original is formed on the photosensitive drums 33Y to 33K by the laser light emitted from the optical scanning device 31, and each color is supplied from the developing units 36Y to 36K corresponding to each color. Is supplied onto the photoconductive drums 33Y to 33K, and an unfixed toner image is formed from the electrostatic latent image.

  At this time, the intermediate transfer belt 2 and the primary transfer rollers 38Y to 38K are applied with a bias having a polarity opposite to the charging polarity of the toner of the unfixed toner images on the photosensitive drums 33Y to 33K, and the photosensitive drums 33Y to 33K. And an intermediate transfer belt 2 form a transfer electric field.

  The intermediate transfer belt 2 is rotated in the direction of the arrow b (clockwise in the drawing), and the toner images on the photoconductive drums 33Y to 33K are sequentially superimposed and transferred onto the intermediate transfer belt 2 by the transfer electric field. A full color toner image is formed on the belt 2.

  A sheet-like recording medium is fed from a paper cassette (not shown), and the timing is measured by a registration roller and is fed to the transfer nip of the secondary transfer roller 43 (arrow a).

  At this time, a bias having a polarity opposite to the charging polarity of the toner of the full-color toner image on the intermediate transfer belt 2 is applied to the secondary transfer roller 43, and between the intermediate transfer belt 2 and the secondary transfer roller 43. A transfer electric field is formed.

  Due to the transfer electric field, the full-color toner image on the intermediate transfer belt 2 is collectively transferred onto a sheet-like recording medium held in the transfer nip of the secondary transfer roller 43.

  At this time, transfer residual toner and the like remaining on the surfaces of the photosensitive drums 33Y to 33K are removed from the surfaces of the photosensitive drums 33Y to 33K by the cleaning devices 37Y to 37K. Further, the surfaces of the photosensitive drums 33Y to 33K are subjected to a charge removing action from the charge removing device, and the surface potential thereof is initialized to prepare for the next image formation.

  Further, residual toner remaining on the surface of the intermediate transfer belt 2 is removed from the surface of the intermediate transfer belt 2 by a belt cleaning device.

  The sheet-like recording medium to which the full-color toner image has been transferred is conveyed to the fixing device 47 by the conveying device 45, and heat and pressure are applied to the sheet-like recording medium to fix the full-color toner image.

  The sheet-like recording medium on which the full-color toner image is fixed is discharged to a discharge tray (not shown) of the image forming apparatus 30 and stacked on the discharge tray.

  At this time, the conveyance speed and displacement (skew) of the intermediate transfer belt 2 are detected by the endless moving member detection device 1 shown in FIG. As shown in FIG. 4 (A), the detection area R0 on the intermediate transfer belt 2 is irradiated with a laser beam (see FIG. 2) 5 from the light source 4, and as shown in FIG. A speckle pattern SP that is scattered light of the laser beam 5 is formed on the surface.

  The speckle pattern SP formed in the detection area R0 is controlled by the image pattern acquisition unit 9 based on the acquisition timing from the timing generation unit 11 that has detected the home position mark 3 for each rotation of the intermediate transfer belt 2. The image is taken by the solid-state imaging device of the area sensor 7 and output to the image pattern acquisition means 9 as an image pattern P (steps S1 and S2).

  Specifically, the image pattern P of the intermediate transfer belt 2 having a different time interval different from the constant time interval in the orthogonal movement calculation unit 13 is input to the speed calculation unit 12.

  The orthogonal movement calculation means 13 includes an image pattern P1 for the first rotation of the intermediate transfer belt 2 (see FIG. 7A) P1 and an image pattern for the second and subsequent rotations of the intermediate transfer belt 2 (FIG. 7B). ) Reference) Each of P2 is input.

  7A and 7B schematically show an image pattern P1 captured by a solid-state imaging device having a resolution of 6 pixels × 6 pixels, and the present invention is not limited to this. is not.

  In the speed calculation unit 12, image information of the image pattern P acquired at a different time interval different from the fixed time interval in the orthogonal movement calculation unit 13 is stored in the memory 22, and the image information stored in the memory 22 is also stored. The image information of the newer image pattern P and the image information stored in the memory 22 are subjected to correlation calculation processing and compared, and the conveyance speed of the intermediate transfer belt 2 is detected.

  Further, the speed calculation means 12 sequentially stores the image information of the image pattern P acquired sequentially in the memory 22, and the image of the image pattern P newer than the image information acquired sequentially and stored in the memory 22 sequentially. Since the information and the image information sequentially stored in the memory 22 are subjected to correlation calculation processing and compared, the conveyance speed of the intermediate transfer belt 2 can be detected in real time.

  In the orthogonal movement calculating means 13, the image information of the first image pattern P 1 is stored in the memory 22, the image information of the second and subsequent image patterns P 2, and the first image pattern P 1 stored in the memory 22. The image information is subjected to correlation calculation processing and compared, and displacement (skew) for each rotation of the intermediate transfer belt 2 is detected (step S3: NO, steps S5 to S7).

  Specifically, for example, when the first image pattern P1 and the second and subsequent image patterns P2 as shown in FIGS. 7A and 7B are obtained, the first image pattern P1. On the other hand, the displacement of the speckle pattern SP in the second and subsequent image patterns P2 is represented by a vector indicated by an arrow e.

  That is, when the image pattern P as shown in FIGS. 7A and 7B is obtained, the intermediate transfer belt is caused by the component in the direction Y of the vector indicated by the arrow e of the speckle pattern SP. It can be determined that a shift in 2 has occurred.

  Further, since the displacement in the direction Y of the vector indicated by the arrow e of the speckle pattern SP is one pixel on the image pattern P2, the movement amount (shift amount) corresponding to the one pixel is calculated. be able to.

  Since the image pattern P2 at the home position for each rotation of the intermediate transfer belt 2 (that is, the second and subsequent rotations) and the image pattern P1 at the home position of the first rotation are compared by performing correlation calculation processing, If the intermediate transfer belt 2 is rotated in a state where there is no deviation even if the attachment position of 7 is inclined, the specifications in the image pattern P1 for the first rotation and the image pattern P2 for the second and subsequent rotations. The displacement in the shift direction Y of the blue pattern SP is not detected. For this reason, unnecessary adjustment of the intermediate transfer belt 2 can be prevented.

  Further, when the attachment position of the area sensor 7 is tilted and the intermediate transfer belt 2 is rotated in a state where a deviation occurs, the deviation of the speckle pattern SP on the image pattern P2 in the second and subsequent rotations. Since the displacement in the direction Y can be detected and the shift amount can be detected, the intermediate transfer belt 2 can be adjusted appropriately.

  In this way, the image pattern P1 at the home position of the intermediate transfer belt 2 for the first rotation and the image pattern P2 at the home position of the intermediate transfer belt 2 for the second and subsequent rotations are compared by performing correlation calculation processing, thereby comparing the image pattern P1. Since the displacement (skew) and moving amount (shift amount) in the shift direction of the transfer belt 2 can be detected, a tension posture that becomes an error component with respect to the superposition (color overlap) of the toner images of the respective colors can be detected. By detecting and controlling the tension posture or adjusting the output image, it is possible to obtain a high-precision full-color image without color misregistration.

  Further, since the steering control can be performed based on the detected deviation direction Y and deviation amount, the conveyance position of the intermediate transfer belt 2 can be controlled to be kept constant with respect to the deviation direction Y.

  Therefore, by controlling so that the position of the intermediate transfer belt 2 in the shifting direction Y does not change, it is possible to carry a high-quality full-color toner image with no positional deviation or color deviation on the intermediate transfer belt 2, The accuracy of the output image output from the image forming apparatus 30 can be increased.

  As described above, the endless moving member detection apparatus 1 according to the first embodiment of the present invention includes the light source 4 for irradiating the circulating intermediate transfer belt 2 with the laser beam 5, the two-dimensional An area sensor 7 capable of acquiring an image; and an imaging optical system that forms an image on the area sensor 7 of a speckle pattern SP when the laser beam 5 is irradiated from the light source 4 onto the intermediate transfer belt 2; An image pattern acquisition unit 9 that acquires the speckle pattern SP imaged on the area sensor 7 at regular time intervals as the intermediate transfer belt 2 moves, and an image acquired by the image pattern acquisition unit 9. An endless moving member detection apparatus 1 having speed calculation means 12 for calculating the speed of the intermediate transfer belt 2 by calculating a pattern P, A home position signal generating means for generating a home position signal corresponding to the home position of the intermediate transfer belt 2 and an image pattern P is acquired by the area sensor 7 based on the home position signal from the home position signal generating means. A timing generation unit 11 that generates the acquisition timing of the intermediate transfer belt 2 and a direction perpendicular to the conveyance direction Y of the intermediate transfer belt 2 by calculating the image pattern P acquired by the image pattern acquisition unit 9 (shift direction Y). Image information of the image pattern P at the home position of the intermediate transfer belt 2 acquired based on the acquisition timing from the timing generation unit 11. Is stored in the memory 22, and the orthogonal movement calculating means 13 The image information of the image pattern P stored in the memory 22 is compared with the image information of the image pattern P at the home position of the intermediate transfer belt 2 acquired based on the acquisition timing from the timing generation means 11. Thus, a movement amount (shift amount) in a direction (shift direction Y) perpendicular to the conveyance direction X of the intermediate transfer belt 2 is calculated.

  Further, in the endless moving member detecting apparatus 1 according to the first embodiment of the present invention, the intermediate transfer belt 2 acquired by the orthogonal movement calculating unit 13 based on the initial acquisition timing from the timing generating unit 11. The image information of the image pattern P1 of the first rotation at the home position is stored in the memory 22 and at the home position of the intermediate transfer belt 2 acquired based on the second and subsequent acquisition timings from the timing generation means 11. The image information of the image pattern P2 after the second rotation and the image information of the image pattern P1 of the first rotation stored in the memory 22 are compared and orthogonal to the conveyance direction X of the intermediate transfer belt 2. The movement amount (shift amount) in a certain direction (shift direction Y) is calculated.

  In this manner, the image information of the image pattern P stored in the memory 22 and the image information of the image pattern P acquired based on the acquisition timing from the timing generation unit 11 are compared and calculated by the orthogonal movement calculation unit 13. Since the movement amount (shift amount) in the direction (shift direction Y) orthogonal to the conveyance direction X of the intermediate transfer belt 2 is calculated, even if the mounting posture of the area sensor 7 is tilted, the intermediate transfer belt 2 When no deviation occurs, no change in the deviation direction Y of the speckle pattern SP is detected. For this reason, it is possible to prevent the position of the intermediate transfer belt 2 from being adjusted inappropriately.

  Further, when the mounting posture of the area sensor 7 is inclined and the intermediate transfer belt 2 is shifted, the shift amount of the speckle pattern SP in the shift direction Y can be detected. The position can be adjusted appropriately.

  Further, when the tension posture of the intermediate transfer belt 2 is inclined and the intermediate transfer belt 2 is not shifted, a change in the shift direction Y of the speckle pattern SP is not detected, and the intermediate transfer is not performed. When the tension posture of the belt 2 is inclined and the intermediate transfer belt 2 is shifted, a change in the shift direction of the speckle pattern SP can be detected, so that the position of the intermediate transfer belt 2 is appropriately set. Can be adjusted.

  That is, by comparing and calculating the same position (that is, the home position) with respect to the conveyance direction X of the intermediate transfer belt 2, the inclination of the tension posture of the intermediate transfer belt 2 and the mounting posture of the area sensor 7 are determined. The movement of the speckle pattern SP in the shift direction Y of the intermediate transfer belt 2 can be accurately detected without being affected by both of the tilts, and stable shift control can be performed.

  Further, the speckle pattern SP is sufficiently fine, and the shift amount in the shift direction of the intermediate transfer belt 2 is detected from the displacement of the speckle pattern SP, so that the shift amount of the intermediate transfer belt 2 is detected with high definition. Can do.

  Therefore, it is possible to avoid the possibility of the intermediate transfer belt 2 being dropped or damaged due to erroneous detection of the shift amount of the intermediate transfer belt 2, and to control the meandering of the intermediate transfer belt 2 with high accuracy.

  Further, in the endless moving member detection apparatus 1 according to the first embodiment of the present invention, since the memory 22 is a nonvolatile memory, the image information of the image pattern P (P1) can be stored without supplying power. Since the memory can be held, when the moving member detection apparatus 1 is restarted, the step for storing the image information of the image pattern P (P1) can be omitted, and the process can be shifted to the actual operation quickly. be able to.

  Further, in the endless moving member detection apparatus 1 according to the first embodiment of the present invention, the home position signal generating means includes a home position mark 3 provided on the surface of the intermediate transfer belt 2, and the home position mark 3 However, since the pattern is formed so as to be different with respect to the shifting direction of the intermediate transfer belt 2, the image pattern P captured by the area sensor 7 in the state where the shifting of the intermediate transfer belt 2 is generated. A different pattern 6 of the home position mark 3 is obtained with respect to the lateral direction Y of the intermediate transfer belt 2. For this reason, the approximate position in the shifting direction Y of the intermediate transfer belt 2 can be detected by pattern matching processing or edge detection processing.

  That is, since the absolute position at the home position mark 3 can be detected by the area sensor 7, the detection range of the displacement of the intermediate transfer belt 2 can be expanded and the calculation processing load of the orthogonal movement calculating means 13 can be reduced. Can be planned.

  Further, the endless moving member detection apparatus 1 according to the first embodiment of the present invention includes image information in the conveyance direction X of the intermediate transfer belt 2 among the image information of the image pattern P acquired by the image pattern acquisition unit 9. Since the transport direction area H from which the image is extracted is calculated by the speed calculation unit 12 and the shift direction area V from which the image information in the shift direction Y of the intermediate transfer belt 2 is extracted is calculated by the orthogonal movement calculation unit 13, By reducing the image information in the direction Y, the load of the correlation calculation process in the speed calculation unit 12 can be reduced, and by reducing the image information in the transport direction X, the load of the correlation calculation process in the orthogonal movement calculation unit 13 Can be reduced.

  Further, the endless moving member detection apparatus 1 according to the first embodiment of the present invention stores the data obtained by Fourier transforming the image pattern P in the memory 22, and therefore stores the image pattern P in the memory 22. The capacity of the memory 22 can be reduced as compared with the case of making it.

  In addition, the image forming apparatus 30 according to the first embodiment of the present invention includes photosensitive drums 33Y to 33K on which electrostatic latent images are carried, and chargers 35Y to 35K that charge the photosensitive drums 33Y to 33K. An optical scanning device 31 that forms electrostatic latent images on the photosensitive drums 33Y to 33K, developing devices 36Y to 36K that develop the electrostatic latent images with toner to form toner images, and the toner images The intermediate transfer belt 2 onto which the toner image is transferred and the endless moving member detection device 1 that detects the conveyance speed and displacement of the intermediate transfer belt 2, thereby avoiding the possibility of the intermediate transfer belt 2 being dropped or damaged. Since meandering of the intermediate transfer belt 2 can be controlled with high accuracy, a high-quality image with high image positioning accuracy and positioning accuracy can be formed.

(Second Embodiment)
Next, an endless moving member detection apparatus 1 according to a second embodiment of the present invention will be described. Note that the same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In this embodiment, the home position of the intermediate transfer belt 2 is used as a reference, and the image pattern P for one rotation of the intermediate transfer belt 2 is sequentially acquired from the reference at regular intervals, and the image information of the image pattern P is stored in the memory. The intermediate transfer belt 2 is subjected to correlation calculation processing between the image information of the image pattern P for one rotation stored in the memory 22 and the image information of the image pattern P captured by the area sensor 7. It is different from the endless moving member detection apparatus 1 according to the first embodiment that a shift change within one rotation can be detected.

  That is, the image information of the image pattern P for one rotation of the intermediate transfer belt 2 is stored in the memory 22 as a reference, and the area sensor 7 captured at a position corresponding to the acquisition position of the image information stored in the memory 22 is stored. The correlation between the image information of the image pattern P and the image information corresponding to the acquisition position stored in the memory 22 is calculated.

  Specifically, as shown in FIG. 2, the timing generation unit 11 generates an image pattern P by the area sensor 7 at regular intervals from the time when the home position sensor 10 detects the home position mark (see FIG. 4A) 3. An acquisition timing for acquisition is generated. Further, the acquisition timing generated by the timing generation unit 11 is set to be a plurality of times within one rotation of the intermediate transfer belt 2.

  For this reason, correlation calculation with the image pattern P picked up by the area sensor 7 can be performed after the second rotation of the intermediate transfer belt 2, and a shift change within one rotation of the intermediate transfer belt 2 can be observed. .

  Further, the home position signal and the acquisition timing are count-managed so that the same location on the intermediate transfer belt 2 can be imaged and subjected to correlation calculation.

  As described above, the endless moving member detection apparatus 1 according to the second embodiment of the present invention makes one rotation of the intermediate transfer belt 2 at a constant time period with the home position of the intermediate transfer belt 2 as a reference. Since the image pattern P is acquired and the image information of the image pattern P is stored in the memory 22, it is possible to detect a shift in one rotation of the intermediate transfer belt 2.

(Third embodiment)
Next, an endless moving member detection apparatus 1 according to a third embodiment of the present invention will be described with reference to FIGS. 9 to 12. FIG. 9 is a timing chart of the home position sensor 10 and the image acquisition clock. FIG. 10 is a diagram showing an image pattern P acquired based on the image acquisition clock. FIG. 11 and FIG. 12 are diagrams illustrating the integration of shift components of the intermediate transfer belt 2. Note that the same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, the home position of the intermediate transfer belt 2 is used as a reference, and the image pattern P is sequentially acquired from the reference at regular time intervals, whereby the shift amount of the intermediate transfer belt 2 (movement amount in the shift direction Y) is constant. It differs from the endless moving member detection apparatus 1 according to the first and second embodiments in that it sequentially accumulates in a time period so that the position of the intermediate transfer belt 2 in the shifting direction Y can be detected.

  Specifically, as shown in FIG. 9, the timing generation unit 11 performs a sampling time having a fixed time period after a waiting time (delay time) Td that is a fixed time from when the home position sensor 10 detects the home position mark 3. It is configured to generate Ts.

  The sampling time Ts is a change in the speckle pattern SP (displacement in the transport direction X and displacement in the shift direction Y) when the adjacent image patterns P of the time intervals acquired based on the sampling time Ts are subjected to correlation calculation. Are set to such a period that can be compared.

  That is, the sampling time Ts is a time interval such that the speckle patterns SP overlap between the adjacent image patterns P in the time interval.

  In the endless moving member detection apparatus 1 according to the third embodiment of the present invention thus configured, as shown in FIGS. 10 (A) and 10 (B), the endless moving member detection apparatus 1 is set to 1 when the waiting time Td has elapsed. The image pattern P1 of the sample is acquired, and the image pattern P2 of the second sample is acquired when the first sampling time Ts after the acquisition of the image pattern P1 of the first sample has elapsed.

  At this time, the electronic shutter of the shutter device of the area sensor 7 is cut based on the image acquisition clock generated by the timing generation unit 11, and the data of each pixel is transferred to the image pattern acquisition unit 9 after the set accumulation time. The

  Further, since the intermediate transfer belt 2 moves in the conveyance direction X after the image pattern P1 of the first sample is acquired and before the image pattern P2 of the next second sample is acquired, FIG. Move in the X direction. At the same time, if the intermediate transfer belt 2 is moved in the Y direction, the component in the shifting direction Y is also added, so that the movement occurs in the vector direction e that is the sum of the X direction and the Y direction.

  The orthogonal movement calculation means 13 performs a correlation operation between the acquired image pattern P1 of the first sample and the image pattern P2 of the second sample, and per unit time of the intermediate transfer belt 2 at the first sampling time Ts. The amount of shift (the amount of movement in the shift direction Y) is calculated.

  Further, by decomposing the vector obtained by the correlation calculation into the X direction and the Y direction, the conveyance speed of the intermediate transfer belt 2 and the movement in the shifting direction Y can be obtained.

  A third sample image pattern (not shown) is acquired at the elapse of the second sampling time 2Ts after the acquisition of the second sample image pattern P2, and the orthogonal movement calculation means 13 and the second sample image pattern P2 A correlation calculation with the image pattern of the third sample is performed, and a deviation amount (movement amount in the deviation direction Y) of the intermediate transfer belt 2 per unit time at the second sampling time 2Ts is calculated.

  In this manner, the image patterns P are sequentially acquired at the sampling time Ts having a constant time period, and the shift amount of the intermediate transfer belt 2 is sequentially calculated by the correlation calculation between the adjacent image patterns P in the time interval.

  The shift amounts calculated sequentially are integrated sequentially as shown in FIG. In FIG. 11, the sampling time Ts of a constant cycle is taken on the horizontal axis, and the Y-direction displacement (shift amount) is taken on the vertical axis. In addition, the straight line shown with the broken line in a figure is obtained by carrying out linear regression with respect to the integrated value Ysum of a Y direction displacement.

  In addition, in the sampling at regular intervals, the amount of movement in the transport direction X per unit time is calculated, so that the transport speed of the intermediate transfer belt 2 can be obtained.

  Further, in the case of deviation control of the intermediate transfer belt 2, since positional information of the intermediate transfer belt 2 is necessary, the data in the Y direction obtained by each sampling is integrated by multiplying the sampling period. Then, the position of the intermediate transfer belt 2 in the shift direction can be obtained.

  That is, even if the image pattern P for one rotation of the intermediate transfer belt 2 is not stored as in the second embodiment, it is possible to observe a shift in one rotation of the intermediate transfer belt 2, and the memory 22 savings can be made.

  Since the Y direction vector includes errors such as the inclination of the intermediate transfer belt 2 and the inclination of the area sensor 7, the error is also integrated into the integrated Y-direction displacement integrated value Ysum. There is a possibility that the value will be different from the correct position observed at the home position.

  That is, as shown in FIG. 12A, the Y-direction displacement accumulated value Ysum accumulated by a plurality of turns of the intermediate transfer belt 2 is shifted in the Y-direction by every rotation of the intermediate transfer belt 2. The integrated value Yhp integrated is included.

  For this reason, if the Y-direction position shift at the home position for each rotation of the intermediate transfer belt 2 is Yhp, and the sum of the Y-direction components for each sampling is Ysum, the intermediate transfer belt is not an actual shift. The sum Yerr of the inclination component of 2 and the inclination component of the area sensor 7 is obtained by the following equation 1.

    Yerr = Ysum−Yhp (Formula 1)

  Also, assuming that the time from the home position of the intermediate transfer belt 2 to the sampling is t, and the period of one rotation of the intermediate transfer belt 2 is T, the change Yadj in the Y direction within one rotation as the correct shift data is It is calculated | required by Formula 2.

    Yadj = Ysum−Yerr × (t / T) (Formula 2)

  In this way, as shown in FIG. 12B, since the correct shift position of the home position of the intermediate transfer belt 2 is obtained, the intermediate transfer belt 2 is based on the corrected correct Y-direction displacement (shift amount). The positional deviation in the Y direction can be accurately corrected.

  In FIGS. 12A and 12B, the rotational speed (first rotation T, second rotation 2T, third rotation 3T) of the intermediate transfer belt 2 is taken on the horizontal axis, and the displacement in the Y direction (shift amount). Is on the vertical axis.

  As described above, the endless moving member detection apparatus 1 according to the third embodiment of the present invention moves in the direction of the intermediate transfer belt 2 in a fixed time period with the home position of the intermediate transfer belt 2 as a reference. Since the movement amount (shift amount) of Y is detected and the shift amount of the intermediate transfer belt 2 is measured by the integrated value Ysum of the movement amount, the image pattern for one rotation (particularly, the front circumference) of the intermediate transfer belt 2 is measured. Even if P is not stored, it is possible to observe a shift in one rotation of the intermediate transfer belt 2 and save the memory 22.

(Fourth embodiment)
Next, an endless moving member detection apparatus 1 according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 13 is a diagram showing detection areas R0 to R3 on the intermediate transfer belt 2. As shown in FIG. Note that the same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In this embodiment, a detection area R0 detected by the area sensor 7 for each rotation of the intermediate transfer belt 2 provided with the home position mark 3 for generating a home position signal, and a fourth detection from the detection area R0. By comparing the speckle pattern SP stored in advance over the area R3, the shift direction of the intermediate transfer belt 2 can be determined based on a wide range of speckle patterns SP in the shift direction (Y direction) of the intermediate transfer belt 2. The adjustment is different from the endless moving member detection apparatus 1 according to the first embodiment.

  More specifically, as shown in FIG. 13A, the detection position includes a home position end 2a of the intermediate transfer belt 2 that is located at the same position in the conveyance direction X for each rotation by the home position mark 3. The speckle pattern SP in the area R0, the speckle pattern SP in the second detection area R1 adjacent above the detection area R0, and the specification in the third detection area R2 adjacent above the second detection area R1 And the speckle pattern SP of the fourth detection area R3 adjacent above the third detection area R2 is a memory (see FIG. 2) 22 for both the speed calculation means 12 and the orthogonal movement calculation means 13. Is stored in advance.

  That is, the range from the detection area R0 to the fourth detection area R3 adjacent to each other is the shift detection range W of the intermediate transfer belt 2, and the intermediate transfer belt 2 in the shift detection range W is shown in FIG. The upper speckle pattern SP is stored in the memory 22.

  For this reason, the speckle pattern SP in the deviation detection range W on the intermediate transfer belt 2 and the speckle pattern SP in the detection area R0 detected for each rotation of the intermediate transfer belt 2 are subjected to correlation calculation. The displacement of the intermediate transfer belt 2 can be detected.

  In this manner, the speckle pattern SP in the shift detection range W and the speckle pattern SP in the detection area R0 can be subjected to correlation calculation to detect the displacement of the intermediate transfer belt 2, so that the detection area R0 can be detected. It is possible to enlarge the detection area as compared with the case where only the data is stored in the memory 22.

  For this reason, when the number of pixels of the area sensor 7 is increased and the detection area is enlarged, there is a problem that the storage area of the memory increases as the number of pixels increases. An increase in the storage area can be suppressed by the endless moving member detection device 1 according to the fourth embodiment.

  Further, when the imaging magnification of the imaging optical system of the area sensor 7 is lowered and the detection area is enlarged, there is a problem that the detection resolution is lowered. However, the fourth embodiment of the present invention has the problem. Such an endless moving member detection device 1 can prevent a decrease in detection and decomposition.

  Further, for example, in an image apparatus that forms an image on a large sheet-like recording medium such as an A3 printer, an intermediate transfer belt 2 having a circumferential length of about 1 meter and a width in a lateral direction Y of about 350 millimeters is used. In many cases, in an image forming apparatus or an electrophotographic apparatus for production, an intermediate transfer belt 2 having a circumference exceeding 2 meters may be used.

  When the intermediate transfer belt 2 having such a size is installed in the image forming apparatus 30, precise alignment is difficult, and a positional deviation of about ± 5 mm is expected. On the other hand, the accuracy of the color shift required for the image is about 20 to 30 micrometers, and when trying to control the shift of the intermediate transfer belt 2, it is 2 to 3 micrometers (1/10 of the color shift precision). A resolution for detecting misalignment is required.

  In addition, when trying to obtain a resolution of position shift detection of 2 to 3 micrometers, the area sensor 7 having a very large pixel size is required, and the amount of correlation calculation is enormous. However, since the endless moving member detection apparatus 1 according to the fourth embodiment of the present invention can use the area sensor 7 having a relatively small pixel size, the storage area and the calculation amount can be suppressed. .

  When acquiring the speckle pattern SP in the deviation detection range W on the intermediate transfer belt 2 as a reference image, for example, acquiring the speckle pattern SP in the detection area R0 including the end 2a of the intermediate transfer belt 2. Thereafter, a desired shift is generated in the intermediate transfer belt 2 by the steering adjustment device 19, and the speckle pattern SP in the second detection area R1, the speckle pattern SP in the third detection area R2, and the speckle pattern in the fourth detection area R3. Obtain SP sequentially.

  At this time, as shown in FIG. 13A, an overlapping portion B1 between the detection area R0 and the second detection area R1 is formed, and an overlapping portion B2 between the second detection area R1 and the third detection area R2 is formed. Then, an image is picked up by the area sensor 7 so that a part of the detection areas overlap each other so that an overlapping part B3 between the third detection area R3 and the fourth detection area R4 is formed.

  When each speckle pattern SP from the detection area R0 to the fourth detection area R3 has been captured, the operation is shifted to an actual operation for image formation, and adjustment is performed by the steering adjustment device 19 so that the intermediate transfer belt 2 is not shifted. .

  In actual operation, for example, when the speckle pattern SP of the detection area R0 captured by the area sensor 7 is compared with the speckle pattern SP of the detection area R0 stored in the memory 22, there is no correlation. A correlation between the speckle pattern SP in the second detection area R1, the speckle pattern SP in the third detection area R2, and the speckle pattern SP in the fourth detection area R3 is sequentially performed, and the position of the intermediate transfer belt 2 is specified.

  When the shift position is specified, intermediate transfer is performed by the steering adjustment device 19 so that the speckle pattern SP in the specified detection areas R1 to R3 and the speckle pattern SP of the detection area R0 imaged by the area sensor 7 are matched. Adjust the belt 2 offset.

  As described above, by storing the speckle pattern SP of each of the areas R0 to R4 as a plurality of reference images, it is possible to suppress a decrease in detection resolution and an increase in the load of arithmetic processing, and a shift detection range W Can be enlarged to an arbitrary size.

  The shift detection range W can be expanded more than the range of the detection area R0 to the fourth detection area R3, and is not limited to the illustrated example.

  As described above, the endless moving member detection apparatus 1 according to the fourth embodiment of the present invention uses the intermediate transfer belt 2 as the image information of the image pattern at the home position of the intermediate transfer belt 2. Since a plurality of image patterns P are acquired for Y and the image information of the plurality of image patterns P is stored in the memory 22, it is possible to prevent the resolution of the area sensor 7 from being lowered, and the correlation calculation processing can be performed. Without increasing the load, the shift detection range W of the intermediate transfer belt 2 can be expanded to an arbitrary size.

(Fifth embodiment)
Next, an image forming apparatus 30 according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 14 is a schematic configuration diagram of the image forming apparatus 30. Note that the same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In this embodiment, the transfer belt 2A is used as the moving member, and the toner images are sequentially superimposed from the photosensitive drums 33Y to 33K on the sheet-like recording medium conveyed by the transfer belt 2A. This is different from the image forming apparatus 30 according to the embodiment.

  Specifically, as shown in FIG. 14, the transfer belt 2 </ b> A stretched around the drive roller 39 and the driven roller 40 is an endless belt, and is the first to fourth embodiments described above. The offset position is adjusted by the endless moving member detection apparatus 1 in FIG.

  Similarly to the intermediate transfer belt 2 described above, the transfer belt 2A is composed of a single layer or a plurality of layers such as PVDF resin, ETFE resin, PI resin, and PC resin, and a conductive material such as carbon black is dispersed therein. The surface of the transfer belt 2A is cleaned by a belt cleaning device (not shown).

  The transfer belt 2A is biased with a polarity opposite to the polarity of the charge of the toner. For this reason, the toner image is transferred onto the sheet-like recording medium conveyed by the transfer belt 2A by attracting the toner from the surface of the photosensitive drums 33Y to 33K to the transfer belt 2A side.

  As described above, the image forming apparatus 30 is a so-called direct transfer system in which the toner image is transferred from the photosensitive drums 33Y to 33K onto the sheet-like recording medium conveyed by the transfer belt 2A.

  As described above, in the image forming apparatus 30 according to the fourth embodiment of the present invention, in the direct transfer type image forming apparatus, the transfer belt 2A is moved closer to the endless moving member detecting device 1 described above. Since the position is adjusted, both the conveyance speed and displacement of the transfer belt 2A can be detected with high accuracy.

  Further, by detecting both the conveyance speed and displacement of the transfer belt 2A with high accuracy, the transfer belt 2A can be controlled with high definition, and a high-quality image with high accuracy can be formed.

  The image forming apparatus 30 described above may be a four-cycle full-color image forming apparatus that transfers each color of yellow, cyan, magenta, and black onto a sheet-like recording medium with a single photosensitive drum.

  The basic operation of the image forming apparatus 30 is an image forming operation when a full-color image is formed on a sheet-like recording medium, and is monochrome using one of the photosensitive drums 33Y to 33K corresponding to each color. An image may be formed, or a two-color or three-color image may be formed using two or three photosensitive drums 33Y to 33K.

  Further, the image forming apparatus 30 can be applied to various image forming apparatuses such as a copying apparatus, a printer, a facsimile, and a plotter as an image forming apparatus to which the present invention can be applied.

  Moreover, although the endless moving member detection apparatus 1 demonstrated the intermediate transfer belt 2 or the transfer belt 2A as an endless moving member, an endless belt-like member or a drum-like member can be adopted.

DESCRIPTION OF SYMBOLS 1 Moving member detection apparatus 2 Intermediate transfer belt (moving member)
3 Home position mark 4 Light source 5 Laser beam (coherent light)
7 Area sensor (solid-state image sensor)
DESCRIPTION OF SYMBOLS 9 Image pattern acquisition means 10 Home position sensor 11 Timing generation means 12 Speed calculation means 13 Orthogonal movement calculation means 14 Control controller 15 Drive part 22 Memory (storage means)
31 Optical scanning device (latent image forming means)
33 Photosensitive drum (latent image carrier)
35 Charger (charging means)
36 Developer (Developer)
R0 detection area (detection area)
R1 Second detection area (detection area)
R2 Third detection area (detection area)
R3 4th detection area (detection area)
P Image pattern P1 First rotation image pattern P2 Second rotation image pattern SP Speckle pattern Td Wait time Ts Sampling time H Transport direction area V Shift direction area X Transport direction Y Shift direction

JP 2009-15240 A JP-A-6-56295

Claims (9)

A light source for irradiating coherent light to the endless moving member that circulates, a solid-state imaging device capable of acquiring a two-dimensional image, and when the endless moving member is irradiated with coherent light from the light source An imaging optical system that forms an image of a speckle pattern on the solid-state imaging device, and an image that acquires the speckle pattern that is imaged on the solid-state imaging device at regular time intervals as the endless moving member moves. An endless moving member detection apparatus comprising: a pattern acquisition unit; and a speed calculation unit that calculates a speed of the endless moving member by calculating an image pattern acquired by the image pattern acquisition unit,
Home position signal generating means for generating a home position signal corresponding to the home position of the endless moving member, and for acquiring an image pattern by the solid-state imaging device based on the home position signal from the home position signal generating means A timing generation means for generating the acquisition timing of the first and second orthogonal movement calculation for calculating a movement amount in a direction orthogonal to the conveying direction of the endless moving member by calculating the image pattern acquired by the image pattern acquisition means Means, and
Image information of the image pattern at the home position of the endless moving member acquired based on the acquisition timing from the timing generation unit is stored in the storage unit,
The orthogonal movement calculating means includes the image information of the image pattern stored in the storage means, and the image information of the image pattern at the home position of the endless moving member acquired based on the acquisition timing from the timing generating means. And calculating an amount of movement in a direction perpendicular to the conveying direction of the endless moving member.   The orthogonal movement calculating means causes the storage means to store image information of the first image pattern at the home position of the endless moving member acquired based on the first acquisition timing from the timing generating means, and the timing Image information of the second and subsequent image patterns at the home position of the endless moving member acquired based on the second and subsequent acquisition timings from the generation unit, and image information of the first image pattern stored in the storage unit The endless moving member detection apparatus according to claim 1, wherein a movement amount in a direction orthogonal to the conveying direction of the endless moving member is calculated.   An image pattern for one rotation of the endless moving member is acquired at a constant time period with respect to a home position of the endless moving member, and image information of the image pattern is stored in the storage unit. The endless moving member detection device according to claim 1.   Detecting the amount of movement of the endless moving member in the direction toward the end with a fixed period of time relative to the home position of the endless moving member, and measuring the amount of shift of the endless moving member based on an integrated value of the amount of movement. The endless moving member detection device according to claim 3.   As the image information of the image pattern of the home position of the endless moving member, a plurality of image patterns are acquired with respect to the direction of the endless moving member and the image information of the plurality of image patterns is stored in the storage unit. The endless moving member detection device according to claim 1, wherein the endless moving member detection device is stored.   The endless moving member detection apparatus according to any one of claims 1 to 5, wherein the storage means is a nonvolatile memory. The home position signal generating means comprises a mark provided on the surface of the endless moving member;
The endless moving member detection device according to any one of claims 1 to 6, wherein the mark is formed so that a pattern is different with respect to a direction toward the endless moving member. .   Among the image information of the image pattern acquired by the image pattern acquisition means, image information in the transport direction of the endless moving member is extracted and calculated by the speed calculation means, and the image in the direction of the endless moving member is shifted. 8. The endless moving member detection apparatus according to claim 1, wherein information is extracted and calculated by the orthogonal movement calculating unit. A latent image carrier on which an electrostatic latent image is carried, charging means for charging the latent image carrier, latent image forming means for forming an electrostatic latent image on the latent image carrier, and the electrostatic latent image Developing means for developing an image with toner to form a toner image, an endless moving member to which the toner image is transferred, an endless moving member detecting device for detecting a conveyance speed and displacement of the endless moving member; In an image forming apparatus having
The endless moving member detection device is the endless moving member detection device according to any one of claims 1 to 8,
The image forming apparatus, wherein the endless moving member is a transfer belt or an intermediate transfer belt.

Images