JP2005126154A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing a photo-sensitive drum from allowing concentration of the electric fatigue caused by image formation started at the same region on the drum at all times depending upon the size of transcription material, precluding image fogging or a drop of the image density, preventing the drum from a drop of its durability, and in a rotor in its fixation part such as a heating roller, pressurizing roller, etc., precluding a thermal deformation etc. of the rotor caused by the heating started at the same region on the rotor, and eliminating a printing loss time till replacement of a damaged rotor which may generate a poor performance of image formation. <P>SOLUTION: The image forming device includes a control means 100 which changes the feeding intervals of the transcription material so that the ratio of the feeding interval L of the transcription material P to the peripheral circumferential length of the rotor (photo-sensitive drum 31, heating roller 381, pressurizing roller 382, etc.) does not become approximately integer times as large and controls a feeding means so as to change the feeding intervals of the transcription material in conformity to the information given by a transcription material feeding interval entering means. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an image forming apparatus using an electrophotographic system such as a printer, a copying machine, and a facsimile, and more particularly, to a transfer material feeding interval.

  In general, as an image carrier using an electrophotographic system, a photosensitive drum type is mainly used because of advantages such as manufacturing and downsizing of an apparatus, and a charging unit is provided around the image carrier (hereinafter referred to as a photosensitive drum). An exposure unit, a development unit, a transfer unit, a cleaning unit, and the like are arranged in the order of processing.

In such an image forming apparatus, image formation on the photosensitive drum is performed by writing with a laser beam in an exposure unit, and in order to form an image on one transfer material, an image region and a non-image are formed on the photosensitive drum. A region needs to be formed.

  In the present invention, the image area indicates a length L1 in the transfer material feeding direction (or the sub-scanning direction of the photosensitive drum), and the non-image area is a reference patch for checking image density or the like. Therefore, a space is provided between the next image area, the length L2 in the feeding direction of the transfer material (or also referred to as a sheet interval) L2, and L1 + L2 = L is referred to as a feeding interval.

  Further, a technique is known in which the interval between the continuously supplied transfer materials is changed in accordance with the transfer material size to secure a minimum inter-paper area for forming a detectable potential pattern (for example, Patent Document 1).

  In addition, when an image carrier (photosensitive drum, transfer belt, etc.) or a rotating body (heating roller, heating belt, etc.) is damaged for some reason, and an image defect occurs on the transfer material, image formation is performed. It is necessary to stop the device and remove the cause.

Depending on the cause, it is necessary to replace the rotating body, and parts are replaced by a service person. During this time, the image forming apparatus is stopped, and printing cannot be performed.
JP-A-9-127830

Therefore, in order to form an image on one transfer material, the length of the photosensitive drum in the sub-scanning direction, that is, the feeding interval L = L1 + L2 is necessary.
Since L1 corresponds to the transfer material size and L2 is constant regardless of the transfer material size, L is set corresponding to the size of the transfer material.

  On the other hand, since the photosensitive drum diameter D1 is determined in advance by the design concept of the image forming apparatus, the feeding interval L of one transfer material with respect to the photosensitive drum circumference πD1 (sub-scan necessary for image formation) If the ratio of the length in the direction (hereinafter referred to as the transfer interval of the transfer material), i.e., πD1 / L = K1, is substantially an integral multiple, writing of image formation is performed from substantially the same position on the photosensitive drum. Become.

  For example, when the transfer material A4 size is longitudinally fed (L1 = 297 mm), the photosensitive drum diameter D1 = 100 mm, and the paper gap L2 = 17 mm, L = 314 mm, and K1 = πD1 / L≈1, which is a substantially integer multiple.

  Usually, there are many models that adopt a photosensitive drum diameter D1 = 80 to 120 mm, selection of transfer material size (A4 portrait, A4 landscape, A3 portrait, B5 portrait, B5 landscape, B4 portrait, etc.) and setting between papers Depending on the combination, there is a high possibility of being an integer multiple.

  For this reason, when processing a large amount of transfer material of the same size, the same area of the photoconductor drum is always used for image formation, and the carrier trap existing on the photoconductor or the interface between the photoconductor drum substrate and the photoconductor As a result of the accumulation of electric charges in the photoconductor, a residual potential is generated in the photoconductor, causing fatigue of the photoconductor, and this fatigue is also a factor in reducing the life of the photoconductor.

  In the transfer process, active substances such as ozone and NOx generated during corona discharge cause a decrease in initial potential and an increase in dark decay during repeated use, a decrease in resolution due to the surface resistance of the photoconductor, image blurring, image blurring, etc. It is the cause.

  Due to such a phenomenon, only the same area of the photosensitive drum is always subjected to charging, exposure, development, and transfer processes as image areas, and thus electrical fatigue is severe. However, non-image areas do not require exposure and transfer processes, so Less fatigue.

For this reason, problems such as image fogging due to poor charging and image density reduction due to insufficient static elimination during exposure due to an increase in residual potential are caused, and the durability of the photosensitive drum is reduced due to a reduction in the lifetime of the photosensitive member.

Further, in tandem type image forming apparatuses and the like, there are many models that employ an endless transfer belt for image formation, but the entire circumference of the belt is L3, and {L3 / (L1 + L2)} =
Even in the case where K2 indicates a substantially integer multiple, as in the case of the photosensitive drum described above, in a portion that is always subjected to transfer discharge, transfer failure due to photoconductor fatigue accompanying increase in residual potential due to generated ozone, NOx, etc. Occurs, and the durability of the transfer belt is lowered.

Furthermore, in the fixing unit, there are many models that employ a roller heating method, in which case the heat of the heating roller is taken away by the transfer material, but the diameter of the heating roller is D2, as in the case of the photosensitive drum described above, When πD2 / L = K3 indicates a substantially integer multiple, the heat of the heating roller is less deprived by the transfer material in the non-image area, that is, the inter-paper portion, than in the image area, that is, the transfer material portion. The temperature rise of the heating roller that hits the inter-paper portion becomes more intense than that of the heating roller that hits the transfer material portion, causing deformation of the heating roller due to temperature deviation distribution of the heating roller, and causing hot offset and gloss unevenness.

In the heating belt, the entire circumference of the belt is L4, and {L4 / (L1 + L2)} =
Even when K4 indicates a substantially integer multiple, the above-described problem occurs as in the heating roller described above.

Also, in the pressure roller that is paired with a roller heating method or a heating belt method, the amount of heat received from the heating roller or the heating belt is large between the papers, and the temperature rises at that portion, causing the same phenomenon. It will be.

The object of the present invention is to prevent concentration of electrical fatigue of the photosensitive drum due to image formation always being performed from the same area surface of the image carrier depending on the transfer material size, to prevent image fogging and image density reduction, An object of the present invention is to provide a corresponding image forming apparatus so as to prevent a decrease in durability of the photosensitive drum.

  It is another object of the present invention to provide a corresponding image forming apparatus so as to prevent a print loss time until replacement of a damaged rotating body that causes an image defect.

  The above object is achieved by the following image forming apparatus of the present invention.

  (1) At least one endless image carrier that has a charging unit, an exposure unit, and a development unit in the periphery, and carries and rotates the toner image formed in each unit, and toner transferred onto a transfer material The image forming apparatus includes a rotating body that fixes an image on a transfer material, a transfer material feeding unit, and a control unit. The control unit includes an image area and a non-image per image formation in the sub-scanning direction of the image carrier. When the sum of the length with the region is substantially an integral multiple of the length of one rotation of the image carrier or the rotating body, the feeding unit is controlled to change the transfer material feeding interval. An image forming apparatus.

  (2) The image forming apparatus according to (1), wherein the length of the transfer material in the conveyance direction uses information detected by a paper size automatic detection unit.

  (3) The image forming apparatus according to (1), wherein the length of the transfer material in the conveyance direction uses information input from an operation panel.

  (4) The transfer material feeding means, the transfer material feeding interval input means, and the control means, and the control so as to change the transfer material feeding interval according to information from the input means. An image forming apparatus characterized in that the means controls the feeding means.

  (5) At least one endless image carrier that has a charging unit, an exposure unit, and a development unit in the periphery, and carries and rotates the toner images formed in the respective units, and toner transferred onto the transfer material A rotating body for fixing an image on a transfer material, an input means for arbitrarily rotating the image carrier and the rotating body on an operation panel, and a control means, according to information from the input means; The image forming apparatus is controlled by the control means so that the image carrier and the rotating body are independently rotated.

  (6) The image forming apparatus according to (5), wherein an input unit of rotation by the operation panel is an angle.

  The present invention has the following effects.

  According to the first to third aspects of the present invention, the sum of the lengths of the image area and the non-image area in the sub-scanning direction of the image carrier is an abbreviation of the length of one rotation of the image carrier or the rotating body. Since the feeding interval of the transfer material is changed so that it does not become an integral multiple, the durability of the photoconductor is reduced due to image fogging on the image bearing member or a decrease in image density, and the heat of the heating roller or pressure roller of the fixing unit An image forming apparatus capable of preventing deformation is provided.

  According to the fourth aspect of the present invention, the control unit controls the feeding unit so as to change the feeding interval of the transfer material in accordance with information from the feeding interval input unit of the transfer material. Damage to the image carrier or the rotator is caused by widening the gap between the inputs so that the ratio between the length of the circumference of the carrier or the rotator and the feeding interval of the transfer material is approximately an integral multiple. An image forming apparatus capable of preventing occurrence of image defects on a transfer material is provided.

  According to the fifth to sixth aspects of the present invention, since the image carrier and the rotating body are independently rotated in accordance with information from the input means, damaged portions such as scratches on the image carrier or the rotating body are removed. An image forming apparatus that can be brought into the inter-paper area and can prevent image defects on the transfer material is provided.

  FIG. 1 is a block diagram showing the overall structure of the image forming apparatus.

  An automatic document feeder (hereinafter referred to as ADF) 1 is provided on the upper part of the image forming apparatus main body of the present embodiment, and an image reading unit 2, an image forming unit 3, a paper storage unit 4, and a paper feeding unit 5 are provided in the main body. , A reverse paper discharge / refeed unit 6, and an ADU 8 as a circulation reverse means.

  The ADF 1 is a device that sends out originals one by one, conveys the originals to an image reading position, and discharges the originals after image reading to a predetermined place.

The automatic document feeder 1 includes a document placing table 11 on which a document is placed, a document separating unit 12 that separates a document placed on the document placing table 11, and a plurality of documents that are transported by the document separating unit 12. A document conveying means 13 including a plurality of rollers, a document discharging means 14 for discharging a document conveyed by the document conveying means 13, a document discharging table 15 for placing a document discharged by the document discharging means 14,
In addition, the document reversing unit 16 includes a pair of rollers for reversing the front and back of the document when reading images on both sides of the document.

  In terms of the processing process, a plurality of documents (not shown) placed on the document placing table 11 are separated one by one by the document separating means 12 and conveyed toward the image reading position by the document conveying means 13. Is done.

  The document reading position is provided at a lower portion of the document conveying means 13, where an image of the document is read through a slit 21 constituting the image reading section 2, and a document discharge table 15 is read by the document discharge means 14. The paper is discharged upward.

  Further, the ADF 1 is configured to be retractable, and the ADF 1 is raised to open the platen glass 22 so that the original can be directly placed on the platen glass 22 and copied. It is.

  The image reading unit 2 is a means for reading an image of a document to obtain image data, and includes a slit 21, a lamp 231 that is a light source that irradiates the document, and a first mirror 232 that reflects light reflected from the document. From the integrated first mirror unit 23, the second mirror unit 24 that integrates the second mirror 241 that reflects the light from the first mirror 232, and the third mirror 242, and the second mirror unit 24 An imaging lens 25 that forms an image of reflected light on an imaging device (hereinafter referred to as a CCD) 26 described later, and a linear CCD 26 that photoelectrically converts a light image formed by the imaging lens 25 to obtain image information. have.

The image information is temporarily stored in a memory (not shown) after appropriate image processing.

  In a mode in which the document sent by the ADF 1 is read by the image reading unit 2, the first mirror unit 23 and the second mirror unit 24 are fixed at positions as shown in the drawing.

  On the other hand, in an aspect in which an image of a document placed directly on the platen glass 22 is read, the first mirror unit 23 and the second mirror unit 24 are moved along the platen glass while maintaining the optical path length.

  The image forming unit 3 finally forms an image on the transfer material P based on the image data obtained by the image reading unit 2.

  The image forming unit 3 in the embodiment forms an image by an electrophotographic process, and includes a photosensitive drum 31 having a photoconductive photosensitive layer on the surface, and a charging unit that uniformly charges the surface of the photosensitive drum 31. 32. A laser writing system 33 which is an exposure unit that is operated based on image data after image processing and exposes the photosensitive drum 31 to form a latent image, and a latent image formed on the photosensitive drum 31. A developing unit 34 that reversely develops an image to form a toner image, a transfer pole 35 that transfers the toner image onto a transfer material P, and an AC corona discharge from the photosensitive drum 31 onto the transfer material P onto which the toner image has been transferred. A separation pole 36 that promotes separation by performing static elimination, a cleaning unit 37 for cleaning the photosensitive drum 31 after the transfer process is completed, a heating roller type fixing unit 38 for fixing the toner image on the transfer material P, Preliminary and a reverse discharge, re-feeding section 6 and ADU8 described above.

  In the image formation with the above-described configuration, the photosensitive drum 31 rotating in the direction of the arrow is sequentially charged by the charging unit 32 and then electrostatic latent at the point A on the photosensitive drum 31 by dot exposure by the laser writing system 33. The registration roller unit 56 serving as the second paper feeding unit starts to rotate by a registration roller driving motor 560 (see FIG. 2) so that an image is formed and a toner image is formed by the developing unit 34 and then overlapped with the toner image region. Then, the transfer material P is fed in synchronism and transferred onto the transfer material P through the pre-transfer roller pair 57 via the action of the transfer pole 35.

  Thereafter, the transfer material P onto which the toner image has been transferred is separated from the photosensitive drum 31 by the separation pole 36 and is heated and pressed while being held between the heating roller 381 and the pressure roller 382 of the fixing unit 38. The toner image is fixed on the transfer material P.

  Next, the toner is discharged to a paper discharge tray 64 through a fixing discharge roller 61 and a discharge roller 63.

On the other hand, the photosensitive drum 31 that has passed through the transfer region continues to rotate, and the cleaning unit 37.
Thus, the residual toner is removed and preparation for the next image formation is made.

In the embodiment, the separation electrode 36 is provided between the separation electrode 36 and the fixing unit 38.
A conveying belt 39 for conveying the transfer material P separated by the above is provided.

The sheet storage unit 4 includes storage units 405 and 4 each including a storage container that stores the transfer material P in a stacked state.
15, 425 and paper feed units 400, 410, 420 integrally configured with paper feed units 51, 52, 53 as first paper feed means are arranged in the vertical direction,
Transfer materials P of different sizes are accommodated.

  The paper feed units 51, 52, and 53 include paper feed rollers 505, 535, and 555 having substantially fixed positions in a state where the paper feed trays 400, 410, and 420 are pushed into predetermined positions in the apparatus and have been loaded, Including separation rollers 506, 536, 556 for prevention.

  The sheet feeding unit 5 includes a pair of conveying rollers R1, R2, R3, R4, R5, and R6 as conveying units for conveying the transfer material P from each of the sheet feeding trays 400, 410, and 420 to the image forming unit 3. Have.

  PS1 is a photo sensor, and has a function of detecting whether or not the transfer material P fed from the paper feed tray 400 by the paper feed roller 505 has reached the transport roller pair R1 provided downstream of the separation roller 506. Further, it is disposed at a position immediately before the conveying roller pair R1.

  Note that the photosensor PS1 as described above is similarly provided for the paper feed trays 410 and 420.

The reverse paper discharge / refeed unit 6 is an area for refeeding the transfer material P after image formation in accordance with the reverse paper discharge or double-sided copying process, and the transfer material P discharged by the fixing discharge roller 61 There is a switching means 62 for switching the conveyance path between when the sheet is discharged as it is, when the sheet is reversed after being turned upside down, and when the transfer material P is re-fed to form an image on the back surface of the transfer material P. doing.

  FIG. 2 is a block diagram showing an example of the electrical configuration of the image forming apparatus according to the embodiment of the present invention.

  This will be described with reference to FIG.

  1 and 2, reference numeral 100 denotes a control that controls each part of the image forming apparatus, and also performs detection of the passing position of the transfer material P, determination of the image writing position, detection control of the position detection sensor, and the like in the present embodiment. The operation of the photosensitive drum driving motor 310, the registration roller driving motor 560, the fixing heating roller driving motor 380, and the like is controlled.

  Although the image reading unit 2 has been described above, in more detail, reading of image information from a document passing through the image reading position by the ADF 1 or a document placed on the platen glass 22 on the document placing table 11 is movable. The light is reflected by the first mirror unit 23 including the lamp 231 and the first mirror 232 and the second mirror unit 24 including the second mirror 241 and the third mirror 242, and forms an image on the CCD 26 via the imaging lens 25. Is done.

  The line-shaped optical image formed on the CCD 26 is sequentially converted into an electric signal (luminance signal), A / D converted, and subjected to processing such as density conversion and filter processing in the image processing unit 130. The image data is temporarily stored in a memory.

  Further, the image processing unit 130 receives the information on the writing position determined by the control unit 100 and performs control for displacing the writing position in the main scanning direction.

  Reference numeral 140 denotes an image writing unit including a laser writing system 33 that receives a processing result in the image processing unit 130 and writes an image on the photosensitive drum 31 with a laser beam.

  The operation panel unit 7 has keys for setting a copy size selection, a copy number selection, a copy start, a specific copy mode selection, and the like, and has a display function. The signal is sent to the control means 100 by the pressed key. The command is issued to each part of the image forming apparatus and the storage / calculation is executed so as to operate the required function.

  When the initial state is set in advance on the operation panel unit 7, the transfer material size selection, the number of prints, etc. are set, and the copy start key is pressed, the photosensitive drum drive motor 310 is driven based on a command from the control means 100. Then, the photosensitive drum 31 rotates in the direction of the arrow, and the charging drum 32 charges the photosensitive drum 31 uniformly.

  When the photosensitive drum driving motor 310 is started, the photosensitive drum 31 rotates clockwise as shown by an arrow (see FIG. 2), and a potential is applied to the photosensitive drum 31 by the charging action of the charger 32. .

  Thereafter, the image writing unit 140 including an exposure optical system as an image exposure unit serving as a writing unit uses a laser diode as a light emission source, passes through a rotating polygon mirror, and passes through a reflection mirror to the photosensitive drum 31. At the position A indicated by the arrow, image writing in the main scanning direction starts image writing based on the image data stored in the memory of the image processing unit 130, and the photosensitive member is subjected to sub-scanning by the rotation of the photosensitive drum 31. An electrostatic latent image corresponding to the document image is formed on the drum 31.

  FIG. 3 is a flowchart showing control of the transfer material feeding interval, which will be described below.

  The transfer material P stored in the paper storage unit 4 is sent out from the paper storage unit 4 by the rotation of the paper feed roller 505 based on a command from the control unit 100, and then sent out one by one by the separation roller 506 for preventing multilayering. Then, the paper is conveyed toward the registration roller portion 56 (the roller is stopped at this point) via the feed rollers R1 and R4 and the loop forming roller 55 (ST1).

  Whether the sensor PS1 disposed immediately after the downstream side of the separation roller 506 detects the leading edge (hereinafter simply referred to as the leading edge) of the transfer material P in the feeding direction within a preset time from the rotation command of the paper feeding roller 505 Is checked by the control means 100.

  The sensor PS1 detects the rear end of the transfer material P in the feeding direction (hereinafter simply referred to as the rear end), so that the detection time in the transfer direction of the transfer material P and the transfer speed of the transfer material P can be changed. Since the rotation speed is known in advance, the length L1 of the transfer material in the conveyance direction can also be obtained.

  Next, the transfer material P conveyed by the loop forming roller 55 is detected by the sensor PS2 disposed immediately upstream of the conveyance path (ST2), and abuts against the registration roller 56 that has once stopped rotating. Thus, a loop of the transfer material P is formed between the loop forming roller 55 and the registration roller portion 56 (ST3).

  The control means 100 determines whether or not the preset time T1 has been reached from the detection of the leading edge of the transfer material P by the sensor PS2 (ST4). If it is determined that T1 has been reached (YES), the registration roller The drive of the part drive motor 560 is started (ST5).

  On the other hand, if it is determined that T1 has not been reached (NO), ST4 is repeated.

  When the registration roller unit driving motor 560 starts driving, the registration roller unit 56 starts rotating, the transfer material P is re-conveyed, and passes through the pre-transfer roller 57 and is synchronized with the toner image formed on the photosensitive drum 31. Is electrostatically adsorbed while being removed, and is fed to the transfer electrode 35.

  As described above, once the transfer material P is abutted against the registration roller unit 56, it is possible to prevent misalignment of the front end of the transfer material P, variations in conveyance, and the like, and the image writing unit 140 can be easily synchronized. The load on the registration roller drive motor 560 due to the loop formation can be reduced, and an image can be formed on the transfer material P at an accurate position.

  Subsequently, when the rear end of the transfer material P is detected by the sensor PS2 (ST6), the conveyance speed V1 by the constant speed rotation of the registration roller unit 56 and the rear end of the transfer material P are driven by the registration roller unit drive motor 560. From the detection time T11 by the sensor PS2 from the start, the length L1 in the feeding direction of the transfer material P is measured as L1 = T11 × V1 (ST7).

  For special sizes other than the standard size (A4, B4, etc.) of the transfer material P (non-standard size such as wide paper, index paper, etc.), the special size is selected from the operation panel unit 7 in advance. By inputting the length L1 in the feeding direction, the feeding interval L can be set.

  When processing the transfer material P of the same size continuously, it is between the rear end of the transfer material P in the feed direction and the front end of the next transfer material P, that is, between the sheets (or also referred to as a non-image area). L2 is set in advance for the purpose of a reference patch creation region, a potential check region, and the like, and usually about 60 mm is secured.

  Therefore, the feeding interval L necessary for the image forming apparatus to perform image formation on one transfer material P is calculated as L = L1 + L2 (ST8).

  On the other hand, the length of one rotation of each rotator (photosensitive drum 31, heating roller 381, pressure roller 382), that is, the circumferential length is πD1, πD2, where the diameter of each rotator is D1, D2, and D3, respectively. Since it is expressed by πD3, the control means determines whether or not at least one of the values of (L / πD1) = K1, (L / πD2) = K2, and (L / πD3) = K3 is a substantially integer multiple. 100 (ST9).

  The photosensitive drum 31 is not only an image carrier but also a rotating body.

  When it is determined that at least one of K1, K2, and K3 is a substantially integer multiple (YES), the control unit 100 resets the preset sheet interval L2 to L2 + k (k> 0). It does not become an integral multiple (ST10).

  k is selected for a rotating body that has not been determined to be an approximate integer multiple, even if a k-long paper gap is added, a value that does not become an approximate integer multiple is selected, and a value that does not affect the processing capacity decline is set. Is done.

  If it is determined in ST9 that K1, K2, and K3 are not all integer multiples (NO), the rotating body executes a normal continuous processing sequence (ST15).

  Since the sheet interval L2 is set to L2 + k, the feeding interval L + k is obtained, so that L + k> πD1 (or πD2 or πD3), and the rotating body (for example, the case of the photosensitive drum 31 as shown in FIG. 4B). The same applies to the heating roller 381 and the pressure roller 382.) Since the image formation start position shifts by k every rotation of the rotating body, the image forming start position is always shifted on the photosensitive drum 31. It is possible to prevent image formation in the same area.

  In FIG. 4B, (1) to (4) indicate the order of the continuous image forming process of the transfer material P, the arrow indicates the transport direction of the transfer material P, and a conventional processing method is shown for comparison. It is shown as 4 (a).

  The leading edge of the transfer material P that is continuously conveyed is detected by the sensor PS2 (ST11), and is transferred between the loop forming roller 55 and the registration roller unit 56 by striking the registration roller unit 56 that has once stopped rotating. A loop of the material P is formed (ST12).

  The control means 100 determines whether or not a preset time T2 has been reached from detection of the leading edge of the transfer material P by the sensor PS2 (ST13). If it is determined that it has reached (YES), the registration roller unit drive is performed. The driving of the motor 560 is started (ST14).

  On the other hand, if it is determined that T2 has not been reached (NO), (ST13) is repeated.

  The control means 100 may be controlled to drive the registration roller drive motor 560 after a time T2 (a time corresponding to the distance k) plus a preset time.

  In synchronization with the transfer material P that has been transported again by the rotation of the registration roller driving motor 560 of the registration roller unit 56, the control unit 100 sends an exposure start command to the image processing unit 130, and the image data stored in advance is written into the image. The image writing unit 140 forms a latent image on the photosensitive drum 31 through image exposure in the main scanning direction and sub-scanning by rotation of the photosensitive drum 31 by the image writing unit 140. It is possible to secure L2 + k in the interval.

  From the above embodiment, each rotating body has the following effects.

  First, the photosensitive drum 31 will be described. In the photosensitive drum 31, aluminum is mainly used for a drum base, and an OPC (organic photoconductor) photosensitive body as a photosensitive body is used on the base. The laminated type is adopted.

  In the laminated OPC photoreceptor, an undercoat layer is formed on a drum substrate, and a charge carrier generation layer (CGL) and a charge carrier transport layer (CTL) are laminated and coated thereon. The photosensitive layer has a thickness of about 25 μm. ing.

  As described above, since the entire circumference of the photosensitive drum 31 is used, it is possible to disperse carrier traps existing in the photosensitive member and charge accumulation at the photosensitive drum substrate and the photosensitive member interface. Further, the residual potential generated in the photoconductor can be reduced, and the photoconductor is less fatigued, thereby extending the life of the photoconductor.

  With respect to the fixing unit 38, the toner image formed on the photosensitive drum 31 is transferred onto the transfer material P by the transfer electrode 35, and then reliably separated from the photosensitive drum 31 by the separation electrode 36. The toner image is fed to the portion 38 and heated while being held by the heating roller 381 and the pressure roller 382, and the toner image is fixed on the transfer material P.

  The heating roller 381 is configured by providing a Si rubber layer having a thickness of about 1.5 mm as an elastic body on a cylindrical metal core, and coating or tubing with a fluororesin (PFC) as a release layer thereon. A halogen heater lamp is mounted as a heating source inside the cylindrical metal core, a temperature sensor is provided on the surface of the heating roller 381, and the output of the halogen heater lamp is controlled by the detected temperature.

  Further, the diameter of the heating roller 381 prevents the area of the transfer material P heated by the heating roller 381 from being always the same area as shown by the photosensitive drum 31 in FIG. Can do.

  Since the heating roller 381 generally employs D2 = about 50 mm, the most used transfer material size A4 is that one transfer material is heated by two rotations. Become.

  By heating the transfer material P with the heating roller 381 in this way, the surface temperature of the heating roller 381 can be uniformly consumed in the circumferential direction by the transfer material P, and on the heating roller 381 Therefore, the unevenness of the gloss on the transfer material P and the occurrence of high temperature offset due to the deformation of the heating roller 381 such as the distortion in the cylindrical direction and the unevenness of the heat in the circumferential direction can be prevented.

  Note that the same measures can be taken in the heating belt system.

  The pressure roller 382, which is the other roller of the fixing unit 38, is provided with a Si rubber layer having a thickness of about 1.0 mm as an elastic body on a cylindrical metal core, and a fluorine resin (PFC) as a release layer thereon. ) Coating or tubing.

  The Si rubber is made harder than the Si rubber of the heating roller 381, so that the transfer material P is curled toward the pressure roller 382 and prevented from being caught in the heating roller 381.

  Some devices are provided with a halogen heater lamp (having a lower electric capacity than the heating roller 381) inside the cylindrical cored bar of the pressure roller 382 in order to accelerate the rise of the fixing unit 38 in the same manner as the heating roller 381. .

  The diameter of the pressure roller 382 is such that the area of the transfer material P pressed by the pressure roller 382 is always the same area as shown by the photosensitive drum 31 in FIG. Can be prevented.

  Since the pressure roller 382 generally employs around D2 = 50 mm, one transfer material P is pressed by two rotations at the most used transfer material size A4. It will be.

  As the transfer material P is pressed by the pressure roller 382 in this way, the surface temperature of the pressure roller 382 pressed against the heating roller 381 is uniformly consumed by the transfer material P in the circumferential direction. It becomes possible to eliminate unevenness of heat on the pressure roller 382, deformation of the pressure roller 382 such as distortion in the cylindrical direction, and occurrence of uneven gloss or high temperature offset on the transfer material P due to the unevenness of heat in the circumferential direction. Can be prevented.

  On the other hand, conventionally, as shown in FIG. 4B, since image formation is always performed in a concentrated manner on a specified image area on the circumference of the photosensitive drum 31, the electrical connection to the photosensitive drum 31 is performed. Since the photoconductor fatigue due to the load is concentrated on the specified image region, the photoconductor fatigued region and the non-fatigue region at the size of the photoconductor drum 31 are used. And the like, and the photosensitive drum 31 is used on a biased side, so that there is a problem that the life of the photosensitive drum 31 is specified due to fatigue in some areas.

  When the transfer material P on which the toner image is formed is continuously fixed, the heat on the surface of the heating roller 381 corresponding to the sheet passing area of the transfer material P is consumed for heating the transfer material P. In the subsequent inter-sheet area, the heat on the surface of the heating roller 381 is not consumed, and the heat transfer in the feeding direction of the heating roller 381 is small, so that it is accumulated in the inter-sheet area, and the heat is deprived. In order to keep the surface temperature of the heating roller 381 in the sheet passing area at a predetermined fixing temperature, power is supplied to the heating means, so that the heat accumulation in the heating roller section corresponding to the inter-paper area is further increased. The temperature range suitable for fixing is greatly exceeded.

  In the state of overheating as described above, the temperature difference between the paper passing area and the inter-paper area causes gloss unevenness and high temperature offset phenomenon on the transfer material P, and the life of the rubber layer of the heating roller 381 is increased. There was a problem of causing problems such as shortening.

  The pressure roller 382 that forms a pair with the heating roller 381 also exhibits the same phenomenon as the heating roller 381, and in an overheated state as described above, an image area and a non-image area (also referred to as a sheet interval). Due to this temperature difference, there are problems such as uneven glossiness and high temperature offset phenomenon on the transfer material P, and problems such as shortening the life of the rubber layer of the pressure roller 382.

  Further, even when an intermediate transfer belt is used as the image carrier, it can be handled in the same manner as the photosensitive drum 31.

  Thereafter, a normal continuous processing sequence is executed (ST15), and when the number of prints set is reached (ST16), a series of operations are terminated, the apparatus is stopped, and a next image forming processing start command is awaited (ST17). ).

  Next, as another feature of the present embodiment, the following functions are provided.

  That is, when it is determined that an image defect due to scratches or the like by the rotating body occurs on the image-formed transfer material P and it is determined that the rotating body needs to be replaced by a serviceman, the replacement of the rotating body is completed. The device must be stopped until.

  For such a problem, it is possible to avoid stopping the apparatus by the following method.

  FIG. 5 is a flowchart showing control for shifting an image defect such as a scratch on a transfer material between sheets, which will be described below.

  When occurrence of image defects such as scratches is recognized on the image formed and output on the transfer material P (ST21), scratches and scratches generated at equal intervals in the transfer direction of the transfer material P Interval J1 (see FIG. 6A, J1 = S1 + S2 + L2) is measured (ST22).

  As shown in FIG. 6A, S1 is the distance between the trailing edge of the transfer material P (1) in the feeding direction and the tip of the scratch S, and S2 is the leading edge of the transfer material P (2) in the feeding direction and the scratch S. The distance L2 from the leading edge of the paper is between the sheets.

  Next, the interval J1 and the circumference of the rotating body (in the present embodiment, the photosensitive drum 31, the heating roller 381, and the pressure roller 382 as the image carrier, and the diameters are D1, D2, and D3 in order). The lengths (πD1, πD2, πD3) are compared (ST23).

  If it is equal to at least one circumference of the rotating body (YES), the wound rotating body is specified (ST24).

  At this time, it is determined that the damaged rotating body needs to be replaced by an expert such as a serviceman.

  If none of the rotating bodies is equal to the circumference in ST23 (NO), it indicates that the cause of scratches is not applicable to the rotating body. Become.

  Next, the control means 100 determines whether the ratio between the specified circumference of the rotating body and the feeding interval L of the transfer material P is substantially an integral multiple (ST25).

  If it is determined that it is not substantially an integral multiple (NO), if the position of the scratch S is always in the inter-sheet area, an image defect caused by a damaged object such as a scratch on the rotating body on the image of the transfer material P can be obtained. Since the occurrence can be avoided, the feeding interval L of the transfer material P is changed.

  For this purpose, a series of continuous output processes can be performed by increasing the ratio between the circumference of the rotating body and the feeding interval of the transfer material P to an approximately integral multiple, and making the scratched part of the rotating body come in the inter-paper area. It can be executed as a response to replacement of a defective rotating body by a man.

  This method can be used as long as the length of the transfer material P in the transfer material feed direction length of the transfer material P is within the length between the papers at a feeding interval that is approximately an integral multiple, and the merit of using the device without stopping the apparatus There is.

  In order for the scratches S to be always at a fixed position of the feeding interval L of the transfer material P, the ratio between the feeding interval L and the circumferential length of the rotating body having damage such as scratches is approximately an integral multiple. Thus, the control unit 100 extends the time until the re-conveyance of the registration roller drive motor 560 by a time corresponding to m so that the preset sheet interval L2 becomes L2 + m (m> 0) (ST26). By controlling, the feeding interval takes a value that is substantially an integer multiple from L to L + m (see FIG. 6B).

  Next, in order to confirm where the position of the scratch S is on the image formed on the transfer material P, the transfer material P is output and the presence or absence of the scratch S is checked (ST27).

  When there is a scratch S on the transfer material P (YES), the scratch S on the image is measured as a distance J2 (see FIG. 6C) from the leading end of the transfer material P to the leading end of the scratch (see FIG. 6C). ST28).

  If there is no scratch S on the transfer material P (NO), it indicates that the scratch S has shifted to the inter-sheet area, and the process proceeds to ST30.

  Based on the numerical input data from the operation panel unit 7, the control unit 100 identifies the rotating body {photosensitive drum drive motor 310 (FIG. 2) so that the position of the scratch S comes from the determined J2 to the inter-paper area. Or a fixing unit drive motor 380 (see FIG. 2, drives the heating roller 381 and the pressure roller 382)}, and rotates the rotating body at an angle corresponding to the input data (ST29). .

  That is, the amount of shift after the scratch S from FIG. 7 can be determined by assuming that the length of the wound transfer material P in the feed direction is y, the maximum rotation angle (in the place of the scratch S2) (L2 + m + J2) / ( L + m), the minimum rotation angle (at the scratch S1) (y + J2) / (L + m), and from this value, it can be determined how much the corresponding rotating body should be rotated in the feeding direction of the transfer material P. By inputting a corresponding rotation angle from the operation panel unit 7, it is obtained by the control means 100 rotating the corresponding rotating body.

  In this way, it is possible to shift the scratches on the transfer material P to the inter-sheet area, and in this setting state, the rotating body is once put into a standby state, a series of operations are completed, and the apparatus is stopped (ST30). .

  Thereafter, based on the operation start command of the apparatus, the sequence control of a series of image forming processes is started and the continuous image forming process is executed.

1 is an overall configuration diagram of an image forming apparatus. 1 is a block diagram illustrating an electrical configuration of an image forming apparatus. 6 is a flowchart illustrating control of a transfer material feeding interval. The comparison figure which shows making a transcription | transfer material feeding interval substantially integer multiple. 7 is a flowchart showing control for shifting a scratch on a transfer material between sheets. The comparison figure which shows the transfer material continuous processing row | line | column which shifted the damage | wound on a transfer material between paper. The figure which shows the positional relationship in the case of shifting the damage | wound of a rotary body between sheets.

Explanation of symbols

2 Image reading unit 3 Image forming unit 4 Paper storage unit 5 Paper feeding unit 7 Operation panel unit 31 Photosensitive drum 310 Photosensitive drum drive motor 33 Laser writing system 38 Fixing unit 380 Fixing unit drive motor 381 Heating roller 382 Pressure roller 56 Registration roller 560 Registration roller drive motor 100 Control means 130 Image processing unit 140 Image writing unit L Feed interval L1 Transfer material feed interval L2 Paper interval P Transfer material PS1 sensor PS2 sensor S Scratches

Claims (6)

At least one endless image carrier that has a charging unit, an exposure unit, and a developing unit around it, and that supports and rotates the toner images formed at the respective units, and the toner image transferred onto the transfer material A rotating member fixed to the material, a transfer material feeding unit, and a control unit. The control unit includes an image area and a non-image area per image formation in the sub-scanning direction of the image carrier. When the sum of the lengths is substantially an integral multiple of the length of one rotation of the image carrier or the rotating body, the feeding unit is controlled to change the feeding interval of the transfer material. An image forming apparatus. The image forming apparatus according to claim 1, wherein the length of the transfer material in the conveyance direction uses information detected by a paper size automatic detection unit. 2. The image forming apparatus according to claim 1, wherein the length of the transfer material in the conveyance direction uses information input from an operation panel. A transfer material feeding unit; a transfer material feeding interval input unit; and a control unit, wherein the control unit is configured to change the transfer material feeding interval according to information from the input unit. An image forming apparatus that controls a feeding unit. At least one endless image carrier that has a charging unit, an exposure unit, and a developing unit around it, and that supports and rotates the toner images formed at the respective units, and the toner image transferred onto the transfer material A rotating body fixed on the material, an image carrier on the operation panel, an input means for arbitrarily rotating the rotating body, and a control means, and the image according to information from the input means An image forming apparatus, wherein the control unit controls the carrier and the rotating body to rotate independently of each other. The image forming apparatus according to claim 5, wherein an input unit of rotation by the operation panel is an angle.

Images