JP2006085032A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To resolve lateral displacement of a belt-shaped member to form good images in an image forming apparatus wherein a toner image is formed and is finally transferred and fixed onto a transfer object material to form an image on the transfer object material and to form a good image. <P>SOLUTION: A transfer object material carrying belt 17 is separated from a photoreceptor drum 11 to form a toner patch, and a density of the toner patch is measured and cleaning is performed. Thereafter, the transfer object material carrying belt 17 is brought into contact with the photoreceptor drum 11, and then a next image is formed after the transfer object material carrying belt 17 is idled for a period corresponding to the period for which the belt 17 was away from the photoreceptor drum, to resolve the lateral displacement of the belt 17. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus for forming an image on a transfer material by forming a toner image and finally transferring and fixing the toner image on the transfer material.

  Conventionally, an electrostatic latent image is formed on a photoconductor, the electrostatic latent image is developed with toner to form a toner image on the photoconductor, and the toner image is finally transferred onto a transfer material, For example, an image forming apparatus that forms an image on a transfer material by fixing the image on the transfer material by heating and pressurization is widely used as a copier, a laser printer, or the like. In this image forming apparatus, for example, a photoreceptor is formed in a belt shape, or an intermediate transfer body that receives the transfer of a toner image from the photoreceptor and mediates transfer of the toner image to a transfer material is formed in a belt shape. Various types of belt-shaped members may be used, such as a belt-shaped transfer material conveying member that conveys a transfer material that receives a transfer of a toner image.

  In addition, a color image forming apparatus that includes a plurality of photoconductors, forms a toner image of each color on each of the plurality of photoconductors, and transfers the toner images onto a transfer material in a superimposed state. Various types of color image forming apparatuses are also known, such as a type of color image forming apparatus that forms toner images of a plurality of colors on a photoreceptor.

  In such an image forming apparatus, a toner patch is formed and the density of the toner patch is measured using a density detection sensor called an ADC sensor, and the image forming conditions are set so that the density of the toner patch becomes a desired density. There is known a technique of changing and controlling so that the density of an image formed on a transfer material is optimized. The timing for forming the toner patch is different from the normal image forming cycle, for example, the timing for interrupting the formation of a plurality of images, the timing before the execution of the image forming cycle, It may be the timing after the completion of the formation cycle. The toner patch density measurement location by the ADC sensor may be on the photosensitive member, on the intermediate transfer member, or on the transfer material transport member. Such a toner patch is removed by a cleaner after density measurement by an ADC sensor.

  In such a configuration in which the toner patch density is measured using the ADC sensor, it is necessary to prevent the formed toner patch from being inadvertently transferred.

  For example, in Patent Document 1, a toner patch prepared on a photoconductor and used for density measurement is transferred onto a transfer material transport body, and cleaning cannot be sufficiently performed by a transfer material transport body cleaning unit. In order to solve the problem that the transfer material is stained on the back surface, a technology has been proposed in which the transfer material conveying member and the photosensitive member are separated at a timing when the toner patch reaches the transfer portion to prevent the back surface contamination.

  Patent Document 2 discloses a so-called tandem configuration in which a plurality of photoconductors are arranged, and a toner patch created on each photoconductor is transferred onto a transfer material conveyance body or an intermediate transfer body to be the most downstream. In the configuration in which the density is detected at the position of the toner, when the toner density detection pattern passes through the transfer position of each photoconductor, it is reversely transferred onto the photoconductor and the density of the toner patch becomes thin, so that the accurate toner density cannot be detected. On the other hand, a technique has been proposed in which reverse transfer is prevented by reducing the contact pressure of the transfer material conveyance body or intermediate transfer body to the photoconductor at the timing when the toner patch passes through the transfer position of each photoconductor. ing.

In addition to the toner image and toner patch other than the toner image that is finally transferred and fixed on the transfer material, in addition to the purpose of density measurement described above, the photosensitive member, intermediate transfer member, or transfer material transfer When a blade-like cleaner is used as a cleaner for removing toner on the body, the toner is supplied for the purpose of supplying toner to the blade to play a role as a lubricant in order to prevent the blade from turning over. To form a band, to form a toner band for the purpose of expelling old toner in the development, or when multiple photoconductors are provided, the amount of deviation between the multiple toner images formed by these photoconductors can be reduced. In some cases, an image shift detection pattern for detection is formed. When these toner bands and image misalignment detection patterns are formed, the same problems as those in the above-described toner patch formation occur, and in order to prevent this, the transfer material carrier or intermediate transfer body is separated from the photoconductor. It is conceivable to reduce the contact pressure.
JP 2000-075762 A JP 2002-014509 A

  However, in the case of the proposals disclosed in the above-mentioned Patent Documents 1 and 2, the problem of back transfer material back surface contamination and reverse transfer can be solved. The belt that has been held by the contact force with the photosensitive member until then shifts in the width direction of the belt, and the positional deviation of the image with respect to the transfer material (alignment deviation) or the positional deviation of each color image ( Color registration misalignment) occurs, and if it is severe, there is a problem that the belt breaks.

  In view of the above circumstances, an object of the present invention is to provide an image forming apparatus that enables good image formation.

The first image forming apparatus of the image forming apparatus of the present invention that achieves the above object forms an image on a transfer material by forming a toner image and finally transferring and fixing the toner image on the transfer material. In an image forming apparatus for forming
Of the two members including the belt-like member that circulates and moves in contact with each other at a predetermined contact pressure, the toner image is transferred from the first member. A transfer unit that transfers a toner image onto a second member or a transfer material to be conveyed sandwiched between the two members;
A first state in which the two members are in contact with each other at a predetermined contact pressure, and a second state in which the two members are separated from each other or the contact pressure between them is reduced. A control member for controlling
A cleaner for removing toner on one of the two members,
An image forming cycle in which the two members are controlled to the first state to transfer the toner image on the transfer material, including the transfer of the toner image in the transfer unit, and the one member And an adjustment cycle in which the two members are controlled to be in the second state and the toner is removed by the cleaner.
The two members are moved to the second state, the adjustment cycle is executed, the two members are returned to the first state, and the two members are moved to the second state. And a sequence control unit for stopping the image forming apparatus or executing an image forming cycle after the belt-like member is circulated and moved for a time corresponding to the time from the first to the first state. Features.

  The amount of displacement in the width direction of the belt-like member is correlated with the time during which the two members are separated from each other or the contact pressure between them is weakened (the second state).

  Further, the two members are returned from the second state in which the two members are separated from each other or the contact pressure is weakened, to the first state in which the two members are in contact with each other at a normal contact pressure, thereby forming a belt shape. When the member is circulated and moved, the belt-like member gradually returns to the normal position even if the belt-like member is shifted laterally immediately after being returned to the first state.

  The adjustment cycle includes various scenes such as the toner patch formation, the toner band formation, and the image shift detection pattern formation described above, and the connection time of the adjustment cycle differs depending on each scene.

  Therefore, in the first image forming apparatus of the present invention, after the two members are returned to the normal contact pressure (returned to the first state), the second state continues for a time. The belt-shaped member is circulated and moved (idle operation) for a corresponding time, and then the next image forming cycle is executed or the image forming apparatus is stopped after the idling operation. .

  Therefore, in the next image forming cycle, the belt-like member is returned to the normal position, and good image formation is performed. In addition, if the belt-like member is idled and then stopped, it is not necessary to place a cycle for returning the belt-like member to the normal position before the image forming cycle when the operation is resumed thereafter. Can enter.

  The belt-like member returns to the normal position if the idle operation is performed for a sufficient time after the transition from the second state to the first state, but the present invention sets the idle operation time to a time corresponding to the time of the adjustment cycle. By doing so, it is not necessary to take an idling time longer than necessary, and the next operation can be performed in a short time.

The second image forming apparatus of the present invention that achieves the above object forms a toner image, and finally transfers and fixes the toner image onto the transfer material. In an image forming apparatus for forming an image on
Of the two members including the belt-like member that circulates and moves in contact with each other at a predetermined contact pressure, the toner image is transferred from the first member. A transfer unit that transfers a toner image onto a second member or a transfer material to be conveyed sandwiched between the two members;
The two members are divided into a first state in which the two members are in contact with each other at a predetermined contact pressure and a second state in which the two members are separated from each other or the contact pressure between them is weakened. A control member to control;
A cleaner for removing toner on one of the two members,
An image forming cycle in which the two members are controlled to the first state to transfer the toner image on the transfer material, including the transfer of the toner image in the transfer unit, and the one member And an adjustment cycle in which the two members are controlled to be in the second state and the toner is removed by the cleaner.
The adjustment cycle is executed by shifting the two members to the second state, the two members are returned to the first state, and the position in the width direction of the belt-shaped member is determined by the sensor. And a sequence controller for stopping the image forming apparatus or executing an image forming cycle after the belt-like member is circulated and moved until it is detected that the normal position is detected. To do.

  Since the second image forming apparatus of the present invention includes the sensor and detects the presence or absence of lateral displacement of the belt-like member, it can move to the next operation in the shortest time, although the sensor is required.

  Here, in each of the first and second image forming apparatuses of the present invention, the first member is a photosensitive member on which an electrostatic latent image is formed and subjected to development with toner to carry the toner image. The second member may be an intermediate transfer member that receives the transfer of the toner image from the photosensitive member and mediates the transfer of the toner image between the photosensitive member and the transfer material, or the first member. The member is a photosensitive member on which an electrostatic latent image is formed and is subjected to development by toner to carry the toner image, and the second member transfers the transfer target material on a path in contact with the photosensitive member. It may be a material conveying belt, and further, the first member is an intermediate transfer belt that receives the transfer of the toner image and mediates the transfer of the toner image to the transfer material, and the second member is The transfer material transports the transfer material on the path in contact with the intermediate transfer belt. It may be a timber transporting member.

  As described above, the present invention can be applied to image forming apparatuses having various configurations.

  As described above, according to the present invention, the lateral displacement of the belt-like member is eliminated, and good image formation is performed.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention.

  The image forming apparatus 10 includes a photosensitive drum 11 that rotates in the direction of arrow A, a charger 12 that primarily charges the photosensitive drum 11, and a photosensitive drum 11 that is primarily charged, and is modulated based on an image signal. The exposure device 13 irradiates the exposure light 13 a to form an electrostatic latent image on the photosensitive drum 11, and the electrostatic latent image on the photosensitive drum 11 is developed with toner to form a toner image on the photosensitive drum 11. A developing device 14 is provided.

  The image forming apparatus 10 creates a toner image in this way, and further, an image forming cycle for transferring and fixing the toner image onto a transfer material, and a density adjustment for creating a toner patch for density adjustment. Have a cycle.

  The image forming apparatus 10 includes a sensor 15 called an ADC sensor that is used in a density adjustment cycle. Details of the sensor 15 and the density adjustment cycle will be described later. Continue the explanation.

  The image forming apparatus 10 further includes an endless transfer material conveying belt 17 that is stretched between two stretching rollers 161 and 162, and is developed on the photosensitive drum 11 by development by the developing device 14. In synchronism with the movement of the formed toner image to the transfer point T, the transfer material is transported to the transfer point T along the transport path P by the transfer material transport belt 17, and the transfer point T is prepared. The toner image on the photosensitive drum 11 is transferred onto the transfer material by the action of the transfer bias applied to the transfer roller 18. The transferred material that has received the transfer of the toner image is further conveyed to the fixing device 19 and is heated and pressurized to fix the toner image on the transferred material.

  The toner remaining on the photosensitive drum 11 after being transferred onto the transfer material at the transfer point T is removed by a cleaner 20 having a blade 21 in contact with the photosensitive drum 11. When this image forming cycle is executed, the transfer material conveyance belt 17 is in contact with the photosensitive drum 11 as long as the transfer material is not sandwiched between the transfer drum and the photosensitive drum 11.

  The above is the operation of the image forming cycle of the image forming apparatus 10. The operation of each part in this image forming cycle and the operation of each part in the adjustment cycle described below are performed based on instructions from the control unit 21.

  In this image forming apparatus 10, there are a plurality of types of adjustment cycles. In the following, a density adjustment cycle, which is one of them, will be described first.

  The two stretching rollers 161 and 162 and the transfer roll 18 are movable up and down in FIG. 1 under the control of the control unit 21. In the density adjustment cycle, the stretching rollers 161 and 162 and the transfer roll 18 are movable. 1 is in a state where it is lowered to the lower side in FIG. 1, whereby the transfer material conveying belt 17 is separated from the photosensitive drum 11. In this embodiment, the two tension rolls 161 and 162 and the transfer roll 18 correspond to the control member referred to in the present invention.

  In the density adjustment cycle, in the state where the transfer material transport belt 17 is separated from the photosensitive drum 11 in this manner, the exposure device 13 uses the exposure light 13a for forming a patch having a predetermined uniform density. The drum 11 is exposed to form an electrostatic latent image for the patch, the electrostatic latent image is developed by the developing device 14 to form a toner patch on the photosensitive drum 11, and the density of the toner patch is read by the sensor 15. It is done. The toner patch whose density is read by the sensor 15 passes through the transfer point T as it is, and is removed from the photosensitive drum 11 by the cleaner 20. The density measurement value read by the sensor 15 is reflected in the image forming conditions, for example, the light amount adjustment of the exposure light 13a, the development bias adjustment of the developing device 14, and the like. It is not the subject, and detailed description here is omitted.

  In the image forming apparatus 10, there are a plurality of types of density adjustment cycles. A density adjustment cycle in which a plurality of types of toner patches are formed from a low density toner patch to a high density toner patch, the plurality of types of toner patches are measured by the sensor 15, and the image forming conditions are adjusted precisely. There is a density adjustment cycle in which one or a small number of toner patches are formed and measured by the sensor 15 to monitor image formation conditions and make rough adjustments. The time required for the plurality of density adjustment cycles varies. Yes.

  Further, in the image forming apparatus 10 shown in FIG. 1, in addition to the above-described density adjustment cycle, the developing device 14 and the photosensitive drum are configured so that excessive friction does not occur between the blade 21 of the cleaner 20 and the photosensitive drum 11. There is no need for an adjustment cycle in which the toner is discharged onto the blade 11 (that is, a pattern called a toner band is formed on the photosensitive drum 11) and the toner is supplied to the blade 21 as a lubricant, and there is no need to supply the blade 21 with toner. However, the toner in the developing device 64 is discharged onto the photosensitive drum 11 to form a toner band on the photosensitive drum 11 for the purpose of discharging toner that has remained in the developing device for a long period of time and has deteriorated due to stirring during that time. There is an adjustment cycle in which the toner band is removed by the cleaner 20. Also in these adjustment cycles, the transfer material conveying belt 17 is in a state of being separated from the photosensitive drum 11.

  As described above, the image forming apparatus 10 shown in FIG. 1 has a plurality of types of adjustment cycles, and the time required for each adjustment cycle is also different.

  Here, in the adjustment cycle, the transfer material conveyance belt 17 is in a state of being separated from the photosensitive drum 11, but the mechanical drive mechanism is connected, and the transfer material conveyance belt 17 is connected to the photosensitive drum 11. Circulate as it rotates. The transfer material transport belt 17 is devised so as not to cause a lateral shift (shift in a direction perpendicular to the paper surface of FIG. 1) when contacting the photoconductive drum 11 with a predetermined contact pressure. If it rotates in a state away from the drum 11, a lateral shift may occur.

  FIG. 2 is a diagram illustrating the relationship between the separation time (sec) and the shift amount (μm).

  As illustrated in FIG. 2, when the transfer material conveying belt 17 of FIG. 1 rotates while being separated from the photosensitive drum 11, the longer the rotation time (separation time) of the transfer material is, the longer the transfer time is. The amount of lateral deviation of the material conveying belt 17 increases.

  FIG. 3 is a diagram illustrating the relationship between the elapsed time (sec) after contact and the deviation (μm).

  When the transfer material conveying belt 17 is brought into contact with the photosensitive belt 11 again with a predetermined contact pressure while causing a lateral deviation, as illustrated in FIG. Return to.

  Returning to FIG. 1, the description will be continued.

  In the image forming apparatus 10 of FIG. 1, the transfer material transport belt 17 is separated from the photosensitive drum 11 and some adjustment cycle is performed. When the adjustment cycle is completed, the control unit 21 causes the stretching rolls 161 and 162 and the transfer roll 18 to move. Rises and the transfer material conveying belt 17 comes into contact with the photosensitive drum 11 with a predetermined contact pressure. The control unit 21 has a correspondence table between the types of adjustment cycles and the idle operation time after the transfer material transport belt 17 is brought into contact with the photosensitive drum 11. Knowing the elapsed time after the material conveying belt 17 is brought into contact with the photosensitive drum 11, and when the time corresponding to the type of the immediately preceding adjustment cycle has elapsed, the image formation is performed when the image data to form an image already exists. When the process proceeds to a cycle and there is no image data to form an image, the operation of the image forming apparatus is stopped.

  FIG. 4 is a diagram illustrating a form of a sequence of an image forming cycle and an adjustment cycle.

  In FIG. 4A, an adjustment cycle for forming a toner patch or a toner band is inserted between two image forming cycles. In the image forming cycle, the transfer material conveying belt 17 (see the drawing) is in contact with the photosensitive drum 11, and in the adjustment cycle, it is in a separated state. When the adjustment cycle is completed, the transfer material transport belt 17 is returned to the state in contact with the photosensitive drum 11, but thereafter, the idle operation is performed for a time corresponding to the time of the immediately previous adjustment cycle, and then the next operation is performed. The image forming cycle is executed.

  In FIG. 4B, when image formation is to be performed, an adjustment cycle is first performed, then an idle operation is performed, and then an image formation cycle is performed.

  In FIG. 4C, after the image forming cycle is completed, the adjustment cycle is executed and the idle operation is performed, and then the operation of the image forming apparatus 10 is stopped.

  Any of these sequences shown in FIGS. 4A to 4C may be adopted, and these sequences may be mixed.

  Here, the transfer material conveying belt 17 is described as being separated from the photosensitive drum 11 in the adjustment cycle, but the transfer material conveying belt is not completely separated from the photosensitive drum 11 but with a weak contact pressure. A reverse bias that prevents the toner on the photosensitive drum 11 from being transferred to the transfer material conveying belt 17 may be applied to the transfer roll 18 in the contact state. In this way, the amount of lateral displacement of the transfer material conveyance belt 17 in the adjustment cycle can be suppressed to a small value, and the idling operation after the transfer material conveyance belt 17 is brought into contact with the photosensitive drum 11 with a normal contact pressure. This shortens the time required for image formation and increases the productivity of image formation.

  FIG. 5 is a schematic configuration diagram of an image forming apparatus according to the second embodiment of the present invention.

  The image forming apparatus 50 includes four photosensitive drums 11Y, 11M, 11C, and 11K that rotate in the direction of arrow A, and around the four photosensitive drums 11Y, 11M, 11C, and 11K. Is based on the image signals on the chargers 12Y, 12M, 12C, and 12K that primarily charge the photosensitive drums 11Y, 11M, 11C, and 11K, and the photosensitive drums 11Y, 11M, 11C, and 11K that are primarily charged. Exposure units 13Y, 13M, 13C, and 13K that irradiate the modulated exposure lights 13Ya, 13Ma, 13Ca, and 13Ka to form electrostatic latent images on the photosensitive drums 11Y, 11M, 11C, and 11K The electrostatic latent images on the body drums 11Y, 11M, 11C, and 11K are toners of various colors (Y: yellow, M: magenta, C: cyan, K: black). It has developed to the photosensitive drums 11Y, 11M, 11C, the developing unit 14Y for forming a toner image of each color on the 11K, 14M, 14C, and 14K.

  Further, the image forming apparatus 50 includes a transfer material conveying belt 17 that is stretched around two stretching rolls 161 and 162 and circulates along the four photosensitive drums 11Y, 11M, 11C, and 11K. In the image forming cycle, the transfer material conveying belt 17 is transferred to each photosensitive drum by transfer rollers 18Y, 18M, 18C, and 18K provided corresponding to the photosensitive drums 11Y, 11M, 11C, and 11K. It is pressed so as to come into contact with 11Y, 11M, 11C, and 11K with a predetermined contact pressure.

  These transfer rolls 18Y, 18M, 18C, and 18K are movable in the direction of contacting and separating from the respective photosensitive drums 11Y, 11M, 11C, and 11K. The transfer rolls 18Y, 18M, 18C, and 18K are control units. In response to the instruction from 21, the transfer material conveyance belt 17 is pressed and adjusted so that the transfer material conveyance belt 17 contacts the photosensitive drums 11Y, 11M, 11C, and 11K with a predetermined contact pressure in the image forming cycle. In the cycle, the transfer material transport belt 17 moves away from the photosensitive drums 11Y, 11M, 11C, and 11K.

  In the image forming cycle, the toner images formed on the photosensitive drums 11Y, 11M, 11C, and 11K are sequentially stacked on the transfer material that has been transferred by the transfer material transfer belt 17 at each transfer point T. It is transcribed as it is. The material to which the toner image is transferred is further conveyed to the fixing device 19 where it is heated and pressurized to fix the toner image on the material to be transferred.

  The toner remaining on the photosensitive drums 11Y, 11M, 11C, and 11K after the toner image is transferred onto the transfer material at the transfer points T is the blades that are in contact with the photosensitive drums 11Y, 11M, 11C, and 11K. It is removed by each of the cleaners 20Y, 20M, 20C, 20K provided with 201Y, 201M, 201C, 201K.

  Further, the image forming apparatus 50 has a density adjustment cycle as a kind of adjustment cycle. In this density adjustment cycle, the transfer material transport belt 17 is separated from the photosensitive drums 11Y, 11M, 11C, and 11K. Toner patches for density measurement are formed on the photosensitive drums 11Y, 11M, 11C, and 11K, and the density is measured by the sensors 15Y, 15M, 15C, and 15K, and the image forming conditions are adjusted.

  There are a plurality of types of density adjustment cycles, and there are also other adjustment cycles such as an adjustment cycle for forming a toner band on the photosensitive drum 11, and the transfer material transport belt 17 is also used in the adjustment cycle. The point of circular movement is the same as in the case of the first embodiment described above.

  The image forming apparatus 50 shown in FIG. 5 is further provided with a sensor 23 that measures the amount of lateral deviation of the transfer material transport belt 17.

  FIG. 6 is a diagram illustrating an arrangement state of sensors for measuring the lateral deviation amount of the transfer material conveyance belt.

  As shown in FIG. 6, the sensor 23 is arranged on both sides of the transfer material conveyance belt 17 so as to sandwich both side edges of the transfer material conveyance belt 17 vertically.

  FIG. 7 is an explanatory diagram of the measurement principle of the sensor shown in FIG.

  The sensor 23 includes a light projecting portion 231 and a light receiving portion 232, and a part of the light flux is blocked by the side edge portion 17 a of the transfer material transport belt 17. When the transfer material transport belt 17 moves in the direction of arrow B due to lateral deviation, the light amount blocked in the light beam changes, and the lateral shift amount of the transfer material transport belt 17 is measured by capturing the change in the light amount by the light receiving unit 232. Is done. As shown in FIG. 6, the lateral deviation amount is measured on both sides of the transfer material conveyance belt 17, and the average value of the lateral deviation measurement values by the two sensors 23 is obtained, whereby the transfer material conveyance belt 17. The partial width fluctuation is canceled, and the lateral deviation amount is measured with high accuracy.

  Returning to FIG.

  The measured value of the lateral deviation amount of the transfer material transport belt 17 from the sensor 23 shown in FIG. In the control unit 21, the adjustment cycle ends, the four transfer rolls 18Y, 18M, 18C, and 18K rise, and the transfer material transport belt 17 is transferred to the photosensitive drums 11Y, 11M, 11C, and 11K for the image forming cycle. After contact with a predetermined contact pressure, the image forming apparatus 50 is idled, and each part is imaged in response to a measurement result from the sensor 23 indicating that the lateral deviation amount of the transfer material transport belt 17 is within a predetermined allowable range. Control for the forming cycle.

  In the case of the image forming apparatus 50 shown in FIG. 5, since the sensor 23 is installed, the lateral deviation amount of the transfer material transport belt 17 is measured in real time, and the image is obtained in the shortest idle time until the lateral deviation amount falls within a predetermined allowable range. Transition to the formation cycle.

  FIG. 8 is a schematic configuration diagram of an image forming apparatus according to the third embodiment of the present invention.

  Here, the elements opposite to the elements of the image forming apparatus 50 of the second embodiment shown in FIG. 5 are denoted by the same reference numerals as those shown in FIG. 5, and only differences will be described.

  The image forming apparatus 60 shown in FIG. 8 includes an intermediate transfer belt 600 in place of the transfer material conveying belt 17 in the image forming apparatus 50 shown in FIG. The intermediate transfer belt 600 is stretched between two stretch rolls 161 and 162 and a secondary transfer roll 601 and circulates in the direction of arrow C. In the case of this image forming apparatus 60, the primary transfer rolls 18Y, 18M, 18C, 18K are not movable like the transfer rolls shown in FIG. 5, and the intermediate transfer belt 600 is always moved to the photosensitive drums 11Y, 11M, 11C and 11K are pressed. On the other hand, the secondary transfer roll 601 provided inside the intermediate transfer belt 600 of the pair of secondary transfer rolls 601 and 602 receives the instruction from the control unit 21 and the intermediate transfer belt 600 is connected to the other transfer belt 600. It moves so as to be in contact with and away from the secondary transfer roll 602.

  Further, in the case of the image forming apparatus 60 shown in FIG. 8, the sensors 15Y, 15M, 15C, and 15K provided for the photosensitive drums 11Y, 11M, 11C, and 11K in the image forming apparatus 50 shown in FIG. As an alternative, a sensor 151 that detects the density and displacement of the toner patch on the intermediate transfer belt 600 is provided.

  In the image forming apparatus 60 shown in FIG. 8, in the image forming cycle, the secondary transfer roll 601 presses the intermediate transfer belt 600 against the other secondary transfer roll 602 so as to have a predetermined contact pressure. The toner images formed on the photosensitive drums 11Y, 11M, 11C, and 11K are transferred so as to be sequentially stacked on the intermediate transfer belt 600 by the action of the primary transfer rolls 18Y, 18M, 18C, and 18K. The toner image transferred onto the intermediate transfer belt 600 is transferred onto the transfer material conveyed to the secondary transfer position T in synchronization with the movement of the toner image by the intermediate transfer belt 600 at the secondary transfer position T. Transcribed. The transfer material is transferred to the fixing device 19 after receiving the transfer of the toner image, and the toner image on the transfer material is fixed to the transfer material. Further, the toner remaining on the intermediate transfer belt 600 after the transfer at the secondary transfer position T is removed from the intermediate transfer belt 600 by the cleaner 603.

  For example, a density adjustment cycle in which a toner patch for density adjustment is formed on the image forming apparatus 60 in FIG. 8 and transferred onto the intermediate transfer belt 600 and the density is measured by the sensor 151 to adjust the image forming conditions. A misregistration detection pattern for detecting the relative misregistration of the toner images formed by the four photosensitive drums 11Y, 11M, 11C, and 11K is formed on the belt 600, and the sensor 151 detects the deviation amount. Then, the adjustment cycle for correcting the deviation and the deteriorated toner accumulated in the developing units 14Y, 14M, 14C, and 14K are discharged onto the photosensitive drums 11Y, 11M, 11C, and 11K and transferred onto the intermediate transfer belt 600. There are a plurality of types of adjustment cycles such as the adjustment cycle removed by the cleaner 603. In executing these adjustment cycles, the control unit 21 controls the secondary transfer roll 601 to move the intermediate transfer belt 600 away from the secondary transfer roll 602. When the adjustment cycle ends, the control unit 21 completes the adjustment cycle. Under the control, the secondary transfer roll 601 comes into contact with the intermediate transfer belt 600 so as to press it. Thereafter, the control unit 21 performs the idling operation, and executes the next image forming cycle upon receiving the detection by the sensor 23 that the lateral shift of the intermediate transfer belt 600 has returned to the allowable range.

  The image forming apparatus 60 shown in FIG. 8 is configured to detect the lateral deviation amount of the intermediate transfer belt 600 using the sensor 23, but as in the case of the present embodiment described with reference to FIG. It may be configured to perform the idling only for the time according to.

  As described above, the image forming apparatus of the present invention can be applied to both a type using a transfer material conveying belt and a type using an intermediate transfer belt, and to both a monochrome type and a color type. Can be applied. Further, although not shown, the present invention can be applied to an image forming apparatus of a type provided with a photosensitive belt instead of the photosensitive drum.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention. It is the figure which showed the relationship between separation time (sec) and deviation | shift amount (micrometer). It is the figure which showed the relationship between the elapsed time (sec) after contact | abutting, and deviation | shift amount (micrometer). It is the figure which showed the form of the sequence of an image formation cycle and an adjustment cycle. It is a schematic block diagram of the image forming apparatus of 2nd Embodiment of this invention. It is a figure which shows the arrangement | positioning state of the sensor which measures the amount of lateral deviation of a to-be-transferred material conveyance belt. It is a measurement principle explanatory drawing of the sensor shown in FIG. It is a schematic block diagram of the image forming apparatus of 3rd Embodiment of this invention.

Explanation of symbols

11, 11Y, 11M, 11C, 11K Photosensitive drum 12, 12Y, 12M, 12C, 12K Charger 13, 13Y, 13M, 13C, 13K Exposure unit 14, 14Y, 14M, 14C, 14K Developing unit 15, 15Y, 15M , 15C, 15K sensor 17 Transfer material conveying belt 18, 18Y, 18M, 18C, 18K Transfer roll 19 Fixing device 21 Control unit 23 Sensor 151 Sensor 600 Intermediate transfer belt

Claims (5)

In an image forming apparatus for forming an image on a transfer material by forming a toner image and finally transferring and fixing the toner image on the transfer material,
Of the two members including the belt-shaped member that circulates and moves in contact with each other at a predetermined contact pressure, the toner image is transferred from the first member. A transfer unit that transfers a toner image onto a second member or a transfer material conveyed by being sandwiched between the two members;
A first state in which the two members are in contact with each other at a predetermined contact pressure; and a second state in which the two members are separated from each other or the contact pressure between them is reduced. A control member for controlling
A cleaner for removing toner on one of the two members;
An image forming cycle in which the two members are controlled to the first state to transfer and fix the toner image on the transfer material, including the transfer of the toner image in the transfer unit, and the one member And an adjustment cycle for controlling the two members to the second state and removing the toner with the cleaner.
The two members are moved to the second state, the adjustment cycle is executed, the two members are returned to the first state, and the two members are further moved to the second state. A sequence control unit that stops the image forming apparatus or executes the image forming cycle after the belt-like member is circulated and moved for a time corresponding to the time from the start to the return to the first state. An image forming apparatus. In an image forming apparatus for forming an image on a transfer material by forming a toner image and finally transferring and fixing the toner image on the transfer material,
Of the two members including the belt-shaped member that circulates and moves in contact with each other at a predetermined contact pressure, the toner image is transferred from the first member. A transfer unit that transfers a toner image onto a second member or a transfer material conveyed by being sandwiched between the two members;
The two members are divided into a first state in which the two members are in contact with each other at a predetermined contact pressure and a second state in which the two members are separated from each other or the contact pressure between each other is weakened. A control member to control;
A cleaner for removing toner on one of the two members;
A sensor for detecting a position in the width direction of the belt-shaped member;
An image forming cycle in which the two members are controlled to the first state to transfer and fix the toner image on the transfer material, including the transfer of the toner image in the transfer unit, and the one member And an adjustment cycle for controlling the two members to the second state and removing the toner with the cleaner.
The adjustment cycle is executed by shifting the two members to the second state, the two members are returned to the first state, and the position of the belt-shaped member in the width direction is further detected by the sensor. A sequence control unit that stops the image forming apparatus or executes the image forming cycle after the belt-like member is circulated and moved until it is detected to be in a predetermined normal position; An image forming apparatus. The first member is a photosensitive member on which an electrostatic latent image is formed and which is developed by toner and carries a toner image;
The second member is an intermediate transfer member that receives transfer of a toner image from the photosensitive member and mediates transfer of the toner image between the photosensitive member and a transfer material. 2. The image forming apparatus according to 2. The first member is a photosensitive member on which an electrostatic latent image is formed and which is developed by toner and carries a toner image;
3. The image forming apparatus according to claim 1, wherein the second member is a transfer material conveyance belt that conveys the transfer material on a path in contact with the photosensitive member. The first member is an intermediate transfer belt that receives transfer of a toner image and mediates transfer of the toner image to a transfer material;
The image forming apparatus according to claim 1, wherein the second member is a transfer material transport member that transports the transfer material on a path in contact with the intermediate transfer belt.

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