JP2008015166A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems that deterioration in electrifying capability and service life in a photoreceptor or an image forming part to which high voltage is applied are affected by application of the high voltage to a region other than an actual image region in the image forming region of the photoreceptor. <P>SOLUTION: The actual image region corresponding to the rotating direction of an image carrier is decided in the actual image region formed on the image carrier for each color component and a high voltage operation in the image forming region is controlled for each color component according to the decided region. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to operation control of an image forming unit in an image forming apparatus.

  In an image forming process such as a copying machine or a printer using an electrophotographic method, after the photosensitive member is charged, the photosensitive member is exposed and developed based on image information in order to record the image electrostatically. Thereafter, the toner image on the photosensitive member is transferred to a recording sheet to form an image. In some systems, the toner image on the photosensitive member is transferred to a recording sheet via an intermediate transfer member to form an image.

  In conventional image forming processes, in particular, each unit that applies a high voltage to the photosensitive member (hereinafter, image forming unit, for example, charging, developing, transferring, and cleaner bias) is controlled in the rotational direction of the photosensitive member for easy control. It is applied in the section corresponding to the paper size.

  However, such high-pressure control tends to cause deterioration of the charging performance of the photoreceptor and the image forming unit, and has a great influence on the life.

In Patent Documents 1 and 2, when the transfer interval to the continuous recording paper is widened, the high voltage applied in accordance with the interval is reduced to suppress the deterioration of the photoconductor, the charging unit, and the transfer unit.
JP 11-125982 A JP 2004-046213 A

  However, the image formed on the recording paper is not necessarily formed on the entire surface of the recording paper. For example, an image may be formed only on a part of a recording sheet at a cover, a page or chapter break, or the like. In such a case, if the high pressure of the image forming unit is applied in a section corresponding to the paper size in the rotation direction of the photoconductor, the high pressure is applied to a region where image formation is not performed. As a result, there is a problem that it affects the deterioration and life of the photoreceptor and the image forming unit.

  If the image formed on the recording paper is black, it is rare that the image is formed on only a part of the recording paper. However, in the case of a color image, a color image is formed on only a part of the recording paper. Is often a monochromatic image. In such a case, when the high pressure of the image forming unit is applied in a section corresponding to the paper size in the rotation direction of the photosensitive member regardless of the color to be formed, the high pressure is applied to a region where no image is formed, Deterioration and life of the photoreceptor and the image forming unit are accelerated. As a result, the frequency of parts replacement is increased, running costs are required, and the amount charged for using the apparatus is also affected.

  The present invention has been made in view of the above-described problems in the prior art. The actual image area corresponding to the rotation direction of the image carrier is determined from the actual image area formed on the image carrier, and the determination is made. An object of the present invention is to provide an image forming apparatus that controls the operation of an image forming unit in accordance with a region.

  In order to achieve the above object, an image forming apparatus according to the present invention mainly includes the following configuration.

  That is, an image carrier, a charging unit for charging the image carrier, an exposure unit for exposing an image to the charged image carrier to form an electrostatic latent image, and developing the electrostatic latent image on the image carrier to a toner image In an image forming apparatus having at least one image forming station comprising a developing means and a transfer means for transferring a toner image of an image carrier to a recording medium, the image is carried in an actual image area where the toner image is formed on the image carrier. The image processing apparatus includes: a determination unit that determines an actual image area corresponding to the rotation direction of the body; and a control unit that controls an operation of any one of the charging unit, the development unit, and the transfer unit based on the determination unit.

  Further, the determining means determines a start position and an end position of the actual image area, and the control means controls an operation according to a period of the start position and the end position.

  Further, when forming a color image, the image forming station is configured to correspond to a plurality of color components forming the color image, and the determining means includes the start position of the actual image region for each of the plurality of color components forming the color image. An end position is determined, and the control unit performs the operation of any one of the charging unit, the developing unit, and the transfer unit for each image forming station with respect to a start position and an end position for each of a plurality of color components forming a color image. It controls according to a period.

  When a color image is formed by a single image forming station, the developing means is configured to correspond to a plurality of color components forming the color image, and the judging means is an actual image area for each of the plurality of color components forming the color image. The control means determines the start position and end position for each of a plurality of color components forming a color image, by controlling the operation of any of the charging means, developing means, and transfer means of the image forming station. It controls according to a period. In the case of forming a color image, the transfer unit includes a second transfer unit that transfers the image onto the intermediate transfer member as a recording medium, and transfers the toner image transferred to the intermediate transfer member onto the recording paper. When controlling the operation of the transfer means, the first start position and the last end position are determined from the start position and end position for each color component obtained by the determination means, and control is performed according to the period. And

  In particular, it has a high voltage supply means for supplying a voltage to any one of the charging means, the developing means, and the transfer means, and the control means controls the high voltage supply means.

  According to the present invention, an actual image region corresponding to the rotation direction of the image carrier is determined in the actual image region where an image is formed on the image carrier, and the operation of the image forming unit is controlled according to the determined region. As a result, the deterioration of the image carrier and the image forming unit can be suppressed. In addition, an image carrier for each color component is determined by determining an actual image area for each of the plurality of color components and controlling the operation of the image forming unit of each image forming station according to the determined actual image area for each color component. And deterioration of the image forming unit can be minimized. Further, when controlling the operation of the second transfer means for the intermediate transfer member, the first start position and the last end position are determined from the start position and end position of the actual image area for each of the plurality of color components, By controlling according to the period, it is possible to suppress deterioration of the intermediate transfer member and the second transfer unit. In particular, by controlling the timing of applying a high voltage to the image forming unit, it is possible to suppress deterioration in charging performance of the image carrier and the image forming unit. As a result of extending the service life, it is possible to improve running costs by reducing the frequency of parts replacement and to optimize the charge amount related to the use of the apparatus.

(First embodiment)
The configuration and operation of the image forming apparatus will be described with reference to FIGS. FIG. 1 is a block diagram of the digital image processing unit 212. FIG. 2 is a cross-sectional view showing the overall configuration of the image forming apparatus. FIG. 3 is a block diagram of the overall control unit 200. FIG. 4 is a diagram showing an external device connected to the external interface (I / F) 213.

  First, the configuration of the color reader unit will be described. An automatic document feeder 202 that automatically feeds a document on the document table glass 201 is mounted on the document table glass 201. A mirror surface pressure plate or a white pressure plate may be mounted instead of the automatic document feeder. The carriage 214 houses light sources 203 and 204, reflectors 205 and 206, and a mirror 207. The light sources 203 and 204 are configured by a halogen lamp, a fluorescent lamp, a xenon tube lamp, or the like, and are provided for illuminating the original on the original table glass 201.

  Light emitted from the light sources 203 and 204 is condensed on the original by the reflectors 205 and 206. The reflected light (image light) is collected on a charge coupled device image sensor (hereinafter, CCD) 101 via a mirror 207, mirrors 208 and 209 in the carriage 215, and a lens 210. At this time, the carriage 214 is moved at a speed V and the carriage 215 is moved at a speed V / 2 and mechanically moved in the sub-scanning direction Y orthogonal to the electrical scanning direction (main scanning direction X) of the CCD 101, thereby Is exposed and scanned.

  The CCD 101 is configured as a color imaging device, and for example, RGB color filters are arranged inline in the order of RGB on a one-line CCD. A color imaging function can be realized by using three light sources of RGB or using a dichroic prism for color separation without using a color filter. The CCD 101 is mounted on a circuit board 211 having a CCD drive circuit. The image signal captured by the CCD 101 is subjected to image processing by the digital image processing unit 212 and output to the printer control I / F 253 via the overall control unit 200.

  The overall control unit 200 is a control unit that controls the entire image forming apparatus, and includes a CPU 301 and a memory 303 as shown in FIG. A digital image processing unit 212, a printer control I / F 253, an external I / F 213, and an operation unit 302 are connected to the CPU 301. The memory 303 stores program codes for controlling the digital image processing unit 212, the printer control I / F 253, and the like. A work area for the CPU 301 to execute the program code is also formed. The memory 303 stores program codes corresponding to flowcharts described later, and is backed up by a secondary battery or the like. The program code may be stored in a ROM (not shown). The printer control I / F 253 is connected to a high voltage supply unit 304 that supplies a voltage to each unit (charging unit, developing unit, transfer unit, secondary transfer unit cleaner bias, etc.) of the image forming unit. The high-voltage supply unit 304 is controlled by the CPU 301 at the timing of supplying a voltage to each unit (charging unit, developing unit, transfer unit, secondary transfer unit cleaner bias, etc.) of the image forming unit.

  The operation unit 302 includes a liquid crystal touch panel, and can easily instruct processing by simply touching an icon indicating processing content. In addition, the execution status of the instructed process, warning information, and the like can be displayed. The external I / F 213 is an external interface with a device outside the apparatus. As shown in FIG. 4, a facsimile apparatus 401, a LAN I / F apparatus 402, and the like are connected to the external I / F 213. Transmission / reception control of image information and code information between the facsimile apparatus 401 and the LAN I / F apparatus 402 is performed by mutual communication between a control unit (not shown) of each connection apparatus and the CPU 301.

  Next, the digital image processing unit 212 will be described with reference to FIG.

  The analog image signal output from the CCD 101 is sampled and held in a clamp & amp & sample hold (S / H) & A / D unit 102. The dark level of the sampled and held analog image signal is clamped at a reference potential, amplified, and converted into, for example, a digital signal of 8 bits for each of RGB. The RGB signal is subjected to shading correction and black correction by the shading unit 103. The corrected RGB signal is input to the stitching & MTF correction correction & document detection unit 104. When the CCD 101 is a three-line CCD, the connection correction is different in the reading position between lines. Therefore, the delay amount for each line is adjusted according to the reading speed, and the signal timing is corrected so that the reading position of the three lines is the same. To do. The MTF correction corrects the change because the reading MTF changes depending on the reading speed and magnification. In the original detection, the original size is recognized by scanning the original on the platen glass 201. The digital signal whose reading position timing is corrected is input to the input masking unit 105. The input masking unit 105 corrects the spectral characteristics of the CCD 101 and the spectral characteristics of the light sources 203 and 204 and the reflectors 205 and 206. The output of the input masking unit 105 is input to a selector 106 that can be switched to the external I / F unit 114. The signal output from the selector 106 is input to the color space compression & background removal & LOG conversion unit 107 and background removal unit 115. The signal input to the background removal unit 115 is input to the black character determination unit 116 after the background is removed, and it is determined whether the document is a black character. The color space compression in the color space compression & background removal & LOG conversion unit 107 determines whether or not the read image signal is within a range that can be reproduced by the printer. If the image signal is not within the range that can be reproduced by the printer, the image signal is corrected so as to be within the range that can be reproduced by the printer. Then, background removal processing is performed, and RGB signals are converted to CMY signals by LOG conversion. Thereafter, the timing of the output signal of the color space compression & background removal & LOG conversion unit 107 is adjusted by a delay 108. The moiré is removed from the output signal of the delay unit 108 and the signal generated by the black character determination unit 116 by the moire removal unit 109, and the magnification processing unit 110 performs the scaling process in the main scanning direction. The signal subjected to the scaling process is input to the UCR & masking & black character reflecting unit 111. In the UCR process, the CMY signal is processed into a yellow (Y), magenta (M), cyan (C), and black (K) signal. The masking process corrects the signal according to the output of the printer. In black character reflection, the determination signal generated by the black character determination unit 116 is fed back to the CMYK signal. The signal processed by the UCR & masking & black character reflecting unit 111 is subjected to density adjustment by the γ correction unit 112 and smoothed or edge processed by the filter unit 113.

  Finally, the image area determination unit 114, which is a feature of the present invention, has a memory (not shown) and outputs the output of the filter unit 113 to the memory 303. Stores data 1 and 0 indicating the presence or absence of data in a memory (not shown). 1 and 0 data indicating the presence or absence of document image data are two-dimensionally mapped into the memory area corresponding to the main scanning direction and the sub-scanning direction of the document image surface, and the color component Y / M / C / K image of the document image. Stored every time. The main scanning direction corresponds to the axial direction of the image carrier, and the sub-scanning direction corresponds to the rotation direction of the image carrier. The first start position and the last end position in the sub-scanning direction for each color component image that is an actual image area in which an actual image is to be formed are the storage addresses in the sub-scanning direction of each memory area stored for each color component image Judgment from. That is, the color component Y image of the original image will be described. In the color component Y image memory, a value of 0 is displayed in a two-dimensional manner corresponding to the main scanning direction and the sub-scanning direction of the original image surface in a portion having no image. Stored, and a value of 1 is stored in a certain part of the image. The first start position and the last end position in the sub-scanning direction, which are actual image areas of the color component Y image of the original image, are the first address and the last address in the sub-scanning direction that store a value of 1 for a certain part of the image. Judgment from the address. Hereinafter, similarly, the first start position and the last end position in the sub-scanning direction, which are actual image areas for each M / C / K image, are one part of an image for each color component M / C / K image memory. Is determined from the first address and the last address in the sub-scanning direction storing the value of. The CPU 301 determines the operation timing of the image forming unit based on the position information, document size, recording paper size, magnification information, process speed, and notifies the printer unit. Note that the determination of the start position and end position of the actual image area is not limited to this.

  The output image from the image processing unit 212 is temporarily stored in the memory 303, and is transmitted from the memory 303 after the CPU 301 notifies the printer unit of necessary information.

  The memory in the image area determination unit 114 that has determined the start position and end position of the actual image area described above may be performed in the memory 303, and the CPU 301 may perform the above determination.

  Next, the configuration of the color printer unit will be described.

  An image forming station for Y / M / C / K that forms a full-color electrostatic image includes the following. The photosensitive member 225Y / 225M / 225C / 225K as an image carrier is rotated in the direction of the arrow by a motor (not shown). Around the photoconductor 225Y / 225M / 225C / 225K, there are a primary charging unit 222Y / 222M / 222C / 222K, an exposure unit 218Y / 218M / 218C / 218K, a developing unit 223Y / 223M / 223C / 223K, and a transfer unit 220Y / 220M. / 220C / 220K, cleaner portion 221Y / 221M / 221C / 221K is arranged.

  The developing unit 223K develops the latent image on the photoreceptor 225K with K toner. The developing units 223Y / 223M / 223C develop the latent image on the photoreceptors 225Y / 225M / 225C with Y, M, and C toners.

  The four color toner images developed on the photoconductors 225Y / 225M / 225C / 225K are collectively transferred to a transfer belt 226 as an intermediate transfer member, which is a recording medium, by a transfer unit 220Y / 220M / 220C / 220K. . The transfer belt 226 is stretched around rollers 227, 228, and 229. The roller 227 functions as a driving roller that is coupled to a driving source (not shown) and drives the transfer belt 226. The roller 228 functions as a tension roller that adjusts the tension of the transfer belt 226. The roller 229 functions as a backup roller for the transfer roller 231 serving as a secondary transfer unit. The transfer roller attaching / detaching unit 250 is a drive unit that causes the transfer roller 231 to adhere to and detach from the transfer belt 226. A cleaner blade 232 is provided at a position facing the roller 227 across the transfer belt 226, and residual toner on the transfer belt 226 is scraped off by the blade 232.

  The cassettes 240 and 241 and the manual paper feed unit 253 have pickup rollers 238, 239 and 254. Recording paper as recording media stored in the cassettes 240 and 241 and the manual paper feeding unit 253 is fed to a nip portion between the transfer roller 231 and the transfer belt 226 by a registration roller 255 and a pair of conveying rollers 235, 236, and 237. The The transfer roller 231 is brought into contact with the transfer belt 226 by driving the transfer roller attaching / detaching unit 250 in the contact direction. The toner image formed on the transfer belt 226 is transferred to the recording paper at the nip portion. The recording paper is heat-fixed by the fixing unit 234 and discharged outside the apparatus. The cassettes 240 and 241 and the manual paper feed unit 253 include sheetless sensors 243, 244, and 245 that detect the presence or absence of recording paper, and paper feed sensors 247, 248, and 249 that detect recording paper pickup defects.

  The color printer configured as described above performs image formation as follows.

  First, the recording paper transport operation in the paper feed unit will be described. The recording sheets stored in the cassettes 240 and 241 are conveyed onto the sheet feeding path 266 one by one by the pickup rollers 238 and 239. The recording paper on the paper feed path 266 is conveyed to the registration roller 255 by the conveyance roller pairs 235, 236, and 237 and is detected by the registration sensor 256. The conveyance of the recording paper is temporarily interrupted after a predetermined time has elapsed when the registration sensor 256 detects the passage of the recording paper. As a result, the recording paper abuts on the stopped registration roller 255 and the conveyance is stopped. The position of the recording paper is fixed so that the end of the recording paper in the traveling direction is perpendicular to the transport path. In this case, correction of paper feed registration in the paper feed path transport direction is performed when skew feeding occurs due to the transport direction of the recording paper deviating from the transport path. Paper registration is essential for minimizing the inclination of the image forming direction with respect to subsequent recording paper. The recording paper is supplied to the transfer roller 231 by activating the registration roller 255 after the paper feeding registration.

  Next, a procedure for forming an image on the recording paper supplied to the transfer roller 231 will be described. First, a voltage is applied to the primary charging units 222Y / 222M / 222C / 222K from the high voltage supply unit 304, and the surface of the photoconductor 225Y / 225M / 225C / 225K is uniformly negatively charged at a specified charging potential. A latent image is formed on the charged photosensitive member 225Y / 225M / 225C / 225K by an exposure unit 218Y / 218M / 218C / 218K including a laser scanner unit so as to have a predetermined exposure potential. The exposure unit 218Y / 218M / 218C / 218K is turned on / off based on the image signal to form a latent image corresponding to the image.

  FIG. 5 is a schematic diagram of the exposure unit. The laser 501 emits the beam L1. The beam L1 enters the rotating polyhedron 502 for scanning the drum via the condenser lens 513. The rotating polyhedron 502 is rotated by a drive motor 503 to deflect the beam L1. The deflected beam light L1 is scanned on the drum 515 at a uniform density via the imaging lens 514. The BD sensor 518 detects the beam light L1 and generates a horizontal synchronization signal in order to make the image writing timing of each line constant.

  A developing bias set in advance for each color from the high-pressure supply unit 304 is applied to the developing rollers of the developing units 223Y / 223M / 223C / 223K. The latent image on the photoconductor 225Y / 225M / 225C / 225K is developed with toner when passing through the position of the developing roller, and is visualized as a toner image. The transfer unit 220Y / 220M / 220C / 220K receives the transfer voltage from the high voltage supply unit 304 and transfers the toner image to the transfer belt 226. The transfer roller 231 is applied with a secondary transfer voltage from the high voltage supply unit 304 and transfers the toner image transferred to the transfer belt 226 onto a recording sheet. The recording paper is conveyed to the fixing unit 234 via the conveyance belt 230. The fixing unit 234 is charged by the pre-fixing charging units 251 and 252 in order to compensate for the toner adsorption force and prevent image disturbance. Thereafter, the toner image of the recording paper is thermally fixed by the fixing roller 233, the transport path is switched to the paper discharge path 258 side by the paper discharge flapper, and the paper is discharged to the paper discharge tray 242.

  The toner remaining on the photoreceptors 225Y / 225M / 225C / 225K is applied with a cleaner bias from a high-pressure supply unit 304 to a preliminary cleaning unit (not shown) so that the toner is easily cleaned, and the cleaner unit 222Y / 221M. Removed and recovered at / 221C / 221K. Finally, the photoreceptors 225Y / 225M / 225C / 225K are neutralized to near 0 volts by a neutralization unit (not shown) and are prepared for the next image forming cycle.

  The image formation start timing of the color printer is Y / M / C / K simultaneous transfer. Therefore, image formation can be performed at an arbitrary position on the transfer belt 226. However, the image formation start timing is determined while shifting the deviation of the position to transfer the toner image on the photoconductor 225Y / 225M / 225C / 225K in a timing manner.

  Since the operation of forming an image on the back side of the recording paper is well known, description thereof is omitted.

  Next, the operation of the image forming unit (charging unit, developing unit, transfer unit, secondary transfer unit cleaner bias, etc.) in each Y / M / C / K image forming station, which is a feature of the present invention, will be described. When the image is formed, the image region determination unit 114 of the digital image processing unit 212 starts and ends the actual image region in the sub-scanning direction for each color component Y / M / C / K image formed on the photoconductor. Determine. The operation of the image forming unit of the Y / M / C / K image forming station is determined according to the result. FIG. 6 is a flowchart of the high-voltage start-up and turn-off timing of the image forming unit. The flowchart shown in FIG. 6 is processed by the CPU 301 of the control unit 200.

First, in step 601 (hereinafter referred to as S601), the above-described image area determination unit 114 determines the start position and the end position of the actual image area in the sub-scanning direction of the first Y / M / C / K image of the image data n = 1. Make a decision.
The CPU 301 determines the operation timing of the image forming unit based on the position information and the like. At that time, image data to be output to the printer unit is variously processed in the digital image processing unit 212, but is not output to the printer unit as it is and is temporarily stored in the memory 303. Thereafter, the image data is read again from the memory 303 using the image writing timing signal as a trigger and output to the printer unit.

  FIG. 7 is a schematic diagram in which the original image is color-separated into Y / M / C / K images, and shows the start position and end position of the actual image area in the sub-scanning direction of the Y / M / C / K image, and the operation timing. In FIG. 7, a document image 701 is composed of a photograph part x, a character part y, and a logo mark part z. When a document image is input, the image is decomposed into a Y component 702, an M component 703, a C component 704, and a K component 705, and the start position and end position of the actual image area are determined for each color component image. Made. The image areas 706 (Y), 706 (M), 706 (C), and 706 (K) in the sub-scanning direction are based on the recording paper size designated by the user. Actually, the operation of the image forming unit is a period (time) corresponding to the actual image areas 707 (Y), 707 (M), 707 (C), and 707 (K) in which the image shown in FIG. 7 is formed. .

  Accordingly, the operation of the image forming unit is started from the start points of the image areas 706 (Y), 706 (M), 706 (C), and 706 (K), and the actual image areas 707 (Y), 707 (M), and 707 ( C), after a time corresponding to the start position of 707 (K). That is, the operation start is determined based on the times 708 (Y), 708 (M), 708 (C), and 708 (K). Similarly, the operation of the image forming unit is terminated from the start point of the image areas 706 (Y), 706 (M), 706 (C), and 706 (K) to the real image areas 707 (Y), 707 (M), and 707 ( C), the time corresponding to the end position of 707 (K). That is, the end of the operation is based on the times 708 (Y), 708 (M), 708 (C), 708 (K) and the times 709 (Y), 709 (M), 709 (C), 709 (K). It is determined.

  In S602, it is checked whether or not the image data is n = 1, that is, the first image data. If it is the first sheet, the process proceeds to S603, and if not, the process proceeds to S604.

If it is immediately after the start of image formation, since the image data n = 1, the process proceeds to S603. In step S603, the image forming unit is raised to a high pressure. FIG. 8 shows a high-pressure start-up sequence of the image forming unit of each image forming station. In S603, operation start times 708 (Y), 708 (M), 708 based on the start positions of the real image areas 707 (Y), 707 (M), 707 (C), 707 (K) determined in S601. In (C) and 708 (K), the image forming unit performs high-pressure startup processing in consideration of a constant startup high-pressure time _TF . In the conventional high-pressure start-up control of the image forming unit, the Y image forming station is used as a base point to take into account the misalignment of each M / C / K image forming station, and is delayed by an offset time T to obtain an image area 706 ( Y), 706 (M), 706 (C), and 706 (K) are started up (dotted line in FIG. 8). However, in the present embodiment, as described above, in the image forming unit of each image forming station of Y / M / C / K, start-up is determined based on the actual start position of the actual image area (see FIG. 8 solid line). The start-up of the secondary transfer unit is a timing at which a color image can be collectively transferred onto a recording sheet after Y / M / C / K image data has been multiple-transferred. That is, the operation of the secondary transfer unit is as follows. When there is one image, the first start position and the last end are selected from the real image areas 707 (Y), 707 (M), 707 (C), and 707 (K). Position. In other words, the operation start uses the first time from the times 708 (Y), 708 (M), 708 (C), and 708 (K), and the operation ends at the times 708 (Y), 708 (M), and 708. The last time is used among the addition times of (C), 708 (K) and times 709 (Y), 709 (M), 709 (C), 709 (K). Then, considering the time, the constant rising high pressure time _TF, and the constant falling high pressure time _TF , the secondary transfer portion is subjected to high pressure rising and falling. FIG. 8 shows the high-pressure startup of the secondary transfer portion.

  In S606, it is determined whether there is subsequent image data n + 1 (= 2). If there is subsequent image data n + 1, an actual image in the sub-scanning direction of the Y / M / C / K image of the image data n + 1 to be output to the printer unit. The start position and end position of the area are determined and the operation is determined. The details of the process are the same as S601, and are omitted. The start position and the end position of the actual image area of the image data n + 1 are necessary to determine the timing of image restart for subsequent image formation and temporary stop of previous image formation.

  In step S607, it is checked whether the image data is n = LAST and the image data of the last sheet. If it is the last sheet, the process proceeds to S608, and if it is not the last sheet, the process proceeds to S609.

  FIG. 9 shows the temporary lowering and starting sequence of the image forming unit at each image forming station.

  In S609, it is determined whether or not to temporarily stop the high-pressure of the image forming unit from the end position of the actual image area of the image data n and the start position of the actual image area of the image data n + 1. If the interval between the end position of the real image area of the image data n and the start position of the real image area of the image data n + 1 has a sufficient margin for the time required for the high voltage rise and fall of the image forming unit, the image The high pressure of the forming part is temporarily stopped. In the conventional high voltage fall control of the image forming unit, the image area 706 is delayed by an offset time T in consideration of the positional deviation of each of the M / C / K image forming stations from the Y image forming station. In accordance with (Y), 706 (M), 706 (C), and 706 (K), the fall is performed (dotted line in FIG. 9). However, in the present embodiment, the fall time is determined in consideration of the end position of the actual image area of the image data n = 1 in each image forming station of Y / M / C / K. That is, the operation end, which is the end position of the real image areas 707 (Y), 707 (M), 707 (C), 707 (K), is time 708 (Y), 708 (M), 708 (C), 708. Based on the addition time of (K) and times 709 (Y), 709 (M), 709 (C), and 709 (K), the high voltage falling of the image forming unit is determined (solid line in FIG. 9). The above-mentioned margin varies depending on the type of high pressure. For this reason, whether or not each fall is possible is determined independently. For example, if it is determined that the falling margin cannot be secured for only some of the high voltages as indicated by the circled portion 9 (a) in FIG. 9, the current high voltage output is continued.

  Further, the high pressure of each part in the temporary stop state is not completely stopped due to the control situation of each high pressure, and a low high pressure output state may be maintained in the recording paper interval.

  When the process is completed so far, the process returns to S602. When the process returns to S602, the processing after the image data n = 2 is performed. In S602, since n = 1 is not satisfied, the process proceeds to S604.

  In step S604, it is determined in step S609 whether the high pressure is temporarily stopped. If not paused, the process proceeds to S606. If it is temporarily stopped, the process proceeds to S605.

  In step S605, a high pressure restart determination process is performed for each unit that is temporarily stopped. The restart timing is set to the interval between the end position of the actual image area of the image data n = 1 and the start position of the actual image area of the image data n + 1 = 2, and the time (margin) required for starting up the high voltage of each part Determine the start-up in consideration. FIG. 9 shows the high-pressure restart sequence in S605. Since these margins differ depending on the high voltage of each part, the startup is determined independently. In some cases, the image data n + 1 may not include any of Y / M / C / K image data. In such a case, the temporary stop process of the image forming unit of each image forming station is continued as it is. In S606, it is determined whether there is subsequent image data n + 1 (= 3). If not, the process proceeds to S607.

  The above processing is repeated until image data n = LAST in S607. S608 is executed when n = LAST.

In S608, an accurate operation end determination is made from the end position of the actual image area with respect to the image data n + 1 (= 2), and image formation fall processing is performed for the high voltage of each part. FIG. 10 shows a high-pressure falling sequence of the image forming unit of each image forming station. In S608, the operation end, which is the end position of the real image areas 707 (Y), 707 (M), 707 (C), and 707 (K) detected in S601 and S606, is time 708 (Y) and 708 (M). , 708 (C), 708 (K) and time 709 (Y), 709 (M), 709 (C), 709 (K) are added to a certain falling high voltage time _TE to form an image. The high-pressure falling process is performed.

  In this embodiment, the operation of the image forming unit is controlled according to the start position and the end position of the actual image area in the sub-scanning direction, thereby minimizing the deterioration of the photoreceptor and the image forming unit and extending the life. Realized.

(Second Embodiment)
Next, the index value X indicating the usage frequency of the photosensitive member and the image forming unit in the present embodiment will be described using the sum of the time applied to the high voltage of the image forming unit with respect to the image forming time and the integrated value of the weighting. For example, the photoreceptor can be expressed by the following formula.

  Here, the high voltage application unit refers to a charging unit, a transfer unit, and the like, and weighting is set to 1 (maximum value) at the time of image formation, and 1 (when the high voltage is not turned off between sheets but in a low voltage state). The following values are used. The number of high voltage applied indicates the number of applied loads.

  If the image formation time for one sheet is 10 seconds and the high voltage of the charging unit is applied to the actual image area during image formation, the weighting is set to 1 and the application time is t1. Further, when the high voltage of the transfer portion is applied to the actual image area during image formation, the weighting is set to 1 and the application time is set to t2. Each of t1 and t2 is smaller than 10 seconds, and t1 + t2 is smaller than 10 seconds. The number of high voltage applied is 2 for the charging part and the transfer part. as a result,

It becomes.

  On the other hand, conventionally, a high voltage is continuously applied during image formation.

Conventionally, the lifetime of the photoconductor is calculated based on the number of copies 1.

In this embodiment, since the lifetime of the photoconductor is obtained based on the actual application time and weighting of each portion of the image forming unit, the lifetime can be calculated with higher accuracy. The above calculation is performed by the CPU 301, and the result is added to the RAM for each load and stored. In this embodiment, the stored index value is a facsimile machine connected via the operation unit 302 or the external I / F 213. And can be displayed on a LAN I / F device. As a result, the service person performs parts replacement or the like using this index value as a guideline, and the running cost can be improved.

  Furthermore, the usage fee of the conventional image forming apparatus is simply calculated from the unit price per sheet as the number of output sheets of recording paper. However, in the present embodiment, it is possible to charge based on the unit price per recording sheet output and the index value X indicating the usage frequency of the photosensitive member or image forming unit for the output. For this reason, even if the color is the same color, even if there is a color image in a part of the area, or even if there is a color image on the entire surface, it is possible to charge only for what was actually used for image formation. Can be realized.

(Other embodiments)
In the present embodiment, a system has been described in which a Y / M / C / K image forming station is independently provided and a color image is formed on a recording sheet via an intermediate transfer member. A system for forming a color image may be used. Alternatively, an image forming apparatus that forms a color image by forming Y / M / C / K image formation on a single photoconductor and multiplexing the image formation on an intermediate transfer member as a recording medium may be used. Furthermore, a monochrome image forming apparatus having a single photosensitive member may be used.

  The present invention also provides a system or apparatus with a storage medium that records software program codes that implement the functions of the embodiments, and the system or apparatus computer (or CPU or MPU) is stored in the storage medium. It is also achieved by reading and executing the program code. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. As a storage medium for supplying such a program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM Etc. can be used.

  Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an OS (operating system) running on the computer based on the instruction of the program code Includes a case where the function of the above-described embodiment is realized by performing part or all of the actual processing.

  Furthermore, after the program code read from the storage medium is written to the memory provided in the function expansion board inserted into the computer or the function expansion unit connected to the computer, the function is based on the instruction of the program code. This includes the case where the CPU of the expansion board or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

  In addition, by distributing the program code of the software that realizes the functions of the above-described embodiments via a network, the program code is stored in a storage unit such as a hard disk or memory of a system or apparatus or a storage medium such as a CD-RW or CD-R. Needless to say, this can also be achieved by the computer (or CPU or MPU) stored in the system or apparatus reading and executing the program code stored in the storage means or the storage medium.

2 is a block diagram of a digital image processing unit 212. FIG. 1 is a cross-sectional view illustrating an overall configuration of an image forming apparatus. 3 is a block diagram of an overall control unit 200. FIG. It is a figure which shows the external device connected to external I / F213. It is a schematic diagram of an exposure part. 6 is a flowchart of start-up timing and fall timing of a high pressure in the image forming unit. A schematic diagram in which an original image is color-separated for each color component Y / M / C / K image shows the start position and end position of the actual image area in the sub-scanning direction of the Y / M / C / K image and the operation timing. The high-pressure startup sequence of the image forming unit of each image forming station is shown. A temporary high voltage lowering and starting sequence of an image forming unit of each image forming station will be described. 2 shows a high-pressure falling sequence of an image forming unit of each image forming station.

Explanation of symbols

212 Digital Image Processing Unit 114 Image Area Discriminating Unit 301 CPU
304 High voltage supply unit 225Y, 225M, 225C, 225K Photosensitive member 222Y, 222M, 222C, 222K Primary charging unit 223Y, 223M, 223C, 223K Developing unit 220Y, 220M, 220C, 220K Transfer unit 231 Secondary transfer unit

Claims (6)

An image carrier, a charging unit for charging the image carrier, an exposure unit for exposing the charged image carrier to form an electrostatic latent image, and the electrostatic latent image on the image carrier as a toner image. In an image forming apparatus having at least one image forming station comprising developing means for developing and transfer means for transferring the toner image of the image carrier to a recording medium,
Determination means for determining the actual image area corresponding to the rotation direction of the image carrier in the actual image area where the toner image is formed on the image carrier;
An image forming apparatus comprising: a control unit that controls an operation of any of the charging unit, the developing unit, and the transfer unit based on the determination unit.   The image according to claim 1, wherein the determination unit determines a start position and an end position of the real image region, and the control unit controls an operation according to a period of the start position and the end position. Forming equipment. When the image is a color image, the image forming station is configured to correspond to a plurality of color components forming the color image,
The determination unit determines a start position and an end position of the real image area for each of a plurality of color components forming the color image;
The control unit performs the operation of any one of the charging unit, the developing unit, and the transfer unit for each of the image forming stations in a period between the start position and the end position for each of a plurality of color components forming the color image. The image forming apparatus according to claim 1, wherein the image forming apparatus is controlled according to the control. When the image is a color image and the image forming station is one, the developing unit is configured to correspond to a plurality of color components forming the color image,
The determination unit determines a start position and an end position of the real image area for each of a plurality of color components forming the color image;
The control means performs any of the operations of the charging means, the developing means, and the transfer means of the image forming station during a period between the start position and the end position for each of a plurality of color components forming the color image. The image forming apparatus according to claim 1, wherein the image forming apparatus is controlled accordingly. When the image is a color image, the transfer unit includes a second transfer unit that transfers the toner image transferred to the intermediate transfer member to a recording sheet as the recording medium.
When the control means controls the operation of the second transfer means, the first start position and the last end position among the start position and the end position for each of the color components obtained by the determination means. The image forming apparatus according to claim 3, wherein the image forming apparatus is controlled according to the period. 6. The high voltage supply means for supplying a voltage to any one of the charging means, the developing means, and the transfer means, and the control means controls the high voltage supply means. The image forming apparatus described in 1.

Images