JP3776168B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reduction in time required for warming up in an image forming apparatus that forms an image using an electrophotographic process.
[0002]
[Prior art]
An image forming apparatus using an electrophotographic process charges a photoconductive photoconductor to a predetermined potential and then irradiates the image or an area other than the image with light to selectively attenuate the potential. An electrostatic latent image is formed, and a toner image obtained by developing the electrostatic latent image with toner as a developer is transferred to a transfer material, thereby forming a copy image of an object to be copied or an image to be printed. .
Around the photoconductor, a charging device that applies a predetermined surface potential to the photoconductor, a developing device that supplies toner to the electrostatic latent image on the photoconductor surface to form a toner image, and the toner image on the photoconductor surface is transferred A transfer device for transferring to the material and a cleaning device for removing residual toner remaining on the surface of the photoconductor and returning the charge distribution on the surface of the photoconductor to the initial state are arranged in order along the direction in which the photoconductor is rotated. Yes. An exposure device that exposes an image on the photoconductor to form an electrostatic latent image is disposed at a position where image information can be exposed upstream of the developing device in the direction in which the photoconductor is rotated. ing. A fixing device for fixing the toner image on the paper is disposed at a position where the paper peeled off from the surface of the photoreceptor by the transfer device is guided.
[0003]
The photoconductor is a photoconductive material such as selenium (Se) or OPC (Organic-Photo Conductor) on the surface of a conductor such as aluminum formed in a rotatable cylindrical or endless belt shape. An optical semiconductor in which a substance is formed to a predetermined thickness. When the photosensitive member is charged to a predetermined potential and irradiated with light from an exposure device to an image or a region other than the image, only the region irradiated with light functions as a conductor and the charged potential is erased. . Thereby, a potential distribution is generated between the region irradiated with light and the other region, and a latent image corresponding to the exposed image is formed on the surface of the photoreceptor.
[0004]
The charging device has a charging wire for corona discharge, and a voltage of 4 to 8 kilovolts is applied via a power supply device connected to the charging wire. Give surface potential.
[0005]
The exposure apparatus irradiates light on the photosensitive member surface with light for generating a potential distribution on the basis of image data stored in advance in an image memory or image data converted from an original image. A latent image is formed.
[0006]
The developing device is opposed to the photosensitive member at a developing position on the surface of the photosensitive member, and a static developer formed on the photosensitive member with a developer including toner and a carrier that frictionally charges the toner to a predetermined polarity and forms a magnetic brush. A toner image is formed by contacting the electrostatic latent image and attaching only toner to the electrostatic latent image. As a developing device, one-component development using only toner or two-component development including toner and carrier is widely used.
[0007]
The transfer device includes a corona discharge device similar to the charging device or a metal roller formed so as to be able to supply a predetermined transfer bias voltage to the photosensitive member, and the toner supplied from the developing device to the electrostatic latent image on the photosensitive member, The toner image formed on the photoconductor is transferred to a transfer material supplied as the photoconductor rotates.
[0008]
The fixing device is a pair of rollers in which a heater is incorporated. The fixing device is electrostatically attached to the transfer material by heating the paper and the toner with a predetermined pressure applied between the rollers. The toner is melted and fixed on the transfer material.
[0009]
The cleaning device has a static elimination lamp that irradiates light on the entire surface of the photoconductor and a cleaner that scrapes off untransferred toner that remains without being transferred to the surface of the photoconductor. The surface state of the photoreceptor is stabilized for the image forming operation.
[0010]
In the image forming apparatus described above, the electrostatic latent image corresponding to the image data is exposed by irradiating the exposure apparatus with light corresponding to the image data while the charging device is charged with a predetermined surface potential by the charging device. Formed in the body.
[0011]
The electrostatic latent image formed on the photoreceptor is developed by a developing device and converted into a toner image.
The transferred toner image is electrostatically attracted to the photoconductor by applying a transfer bias voltage having the same polarity as the surface potential provided to the photoconductor from the back surface of the transfer material via the transfer device. It is transferred to the material.
The toner image transferred to the transfer material is melted by heat from the fixing device, and is fixed to the transfer material by the pressure provided at the same time.
[0012]
[Problems to be solved by the invention]
By the way, the above-mentioned image forming apparatus is used until a predetermined time elapses after the power of the image forming apparatus is turned on for initial warm-up represented by initial (initial movement) check of the apparatus and heating time of the fixing device. During this time, a waiting time during which image formation is not possible is set.
[0013]
For this reason, in the above-described image forming apparatus, when the energization to the apparatus is interrupted for any reason during standby or during the image forming operation, the cause of the interruption of the energization is removed and the energization is performed again. Even in such a case, there is a problem in that image formation cannot be performed until a predetermined time elapses, as in normal warm-up. In this case, the cause of the interruption of the power supply to the image forming apparatus is, for example, a case where the exterior cover of the apparatus that has been on standby by the user who intends to use the image forming apparatus is instantaneously opened. In this case, image formation is prohibited for the same time as normal warm-up.
[0014]
SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of setting an image forming standby state in the shortest time when the energization to the image forming apparatus for forming an image based on the electrophotographic process is temporarily interrupted. Is to provide.
[0015]
[Means for Solving the Problems]
  The present invention has been made on the basis of the above-described problems. Image forming means for forming an image on an image carrier;In the reverse development method, the aboveA developing unit for supplying a developer to the image formed on the image carrier by the image forming unit to form a developer image; and while the developer image is formed on the image carrier by the developing unit.ThroughWhen power is cut offIsAt the next energization,Until the residual potential of the image carrier disappearsWhen rotation of the image carrier is stopped and the power is shut off in a standby state in which formation of the developer image on the image carrier by the developing means is stoppedIsAt the next energization,When the operation history stored in advance in the storage means is referred to and the standby state is determined,the aboveUntil the residual potential of the image carrier disappearsWait time shorter than hoursAt the topAnd an image forming apparatus including a control unit that permits image formation by the image forming unit.
[0016]
  The present invention also provides an image forming means for forming an image on the image carrier,In the reverse development method, the aboveThe image forming means supplies the developer to the image formed on the image carrier to form a developer image, and the developing means can hold data even when the energization is interrupted. A data holding means for holding an operating state indicating whether the developing means and the image forming means immediately before being blocked are forming an image, or whether a predetermined time has elapsed since the check on the charging of the image carrier was performed; When the power is cut off, image formation by the image forming unit is performed at the time when the power is next applied based on the operation state data of the developing unit and the image forming unit held by the data holding unit.In association with the time until the residual potential of the image carrier disappearsAnd an image forming apparatus including a control unit to permit.
[0017]
  Furthermore, the present invention provides an image forming means for forming an image on the image carrier,In the reverse development method, the aboveThis is the case where the developer is supplied to the image formed on the image carrier by the image forming means to form a developer image, and the operation state of the developing means and the image forming means is cut off. Even if the data holding means to be held, and the data on the operating state of the developing means and the image forming means immediately before the energization held by the data holding means is cut off, the development to the image carrier by the developing means are performed. When the power supply is shut off in the standby state where the formation of the agent image is stopped, when the power is turned on next time, the check on charging to the image carrier is omitted and the image by the image forming means is used. And an image forming apparatus including a control unit that permits formation.
  In the image forming apparatus described above, when the power supply to the image forming unit is cut off, the control unit is operating the image forming unit immediately before the power supply to the image forming unit is cut off. If it is energized next time, the image forming operation by the above image formation is prohibited for the time until the residual potential of the image carrier disappears.
[0019]
  Still further, the present invention provides an image carrier that holds an image by selectively changing a potential distribution while being charged to a predetermined potential, and a charging unit that charges the image carrier to a predetermined potential. The developer and a developer holding member that imparts triboelectric charge to the developer are held, and the developer is supplied to the image held by the image carrier to form a developer image.Reverse development methodWhen the energization is interrupted and the energization is resumed immediately after the energization is interrupted, it is based on whether or not the charging of the image carrier by the charging means has been continued immediately before the energization is interrupted.Ki,When the energization is interrupted while the developer image is formed on the image carrier, the image carrier until the remaining potential of the image carrier disappears at the next energization. When the power supply is shut off in a standby state in which the developing means stops forming the developer image on the image carrier by the developing means, it is stored in advance when the power is turned on next time. When the operation history stored in the means is referred to and the standby state is determined, image formation by the image forming means is performed in a standby time shorter than the time until the residual potential of the image carrier disappears. to approveAnd an image forming control unit.
[0020]
  Furthermore, the present invention provides an image carrier that holds an image by selectively changing a potential distribution while being charged to a predetermined potential, and a charging unit that charges the image carrier to a predetermined potential. The developer and a developer holding member that imparts triboelectric charge to the developer are held, and the developer is supplied to the image held by the image carrier to form a developer image.Reverse development methodWhen the energization is interrupted again immediately after the energization is interrupted with the developing means, the charging to the image carrier by the charging means is stopped immediately before the energization is interrupted.Based on the operation history stored in the storage means in advanceDetectIn caseAnd an image forming control means for managing the time during which the operation of the image carrier is stopped to a minimum.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, a laser exposure type copying apparatus 2 generally includes a photosensitive drum 10 on which an electrostatic latent image corresponding to an image to be recorded is formed by a laser beam supplied from a laser exposure apparatus described later. Has in the center.
[0022]
Around the photosensitive drum 10, a charging device 12 that charges the surface of the photosensitive drum 10 to a predetermined potential along the rotational direction of the photosensitive drum 10 indicated by an arrow a, and a laser exposure device described later, the photosensitive member. A developing device 14 that develops an electrostatic latent image by supplying toner as a developer to the latent image formed on the drum 10, and a toner image on the photosensitive drum 10 developed by the developing device 14 as a recording medium. A transfer device 16 for transferring to a sheet of paper, a cleaning device 18 for scraping off untransferred toner remaining on the surface of the photosensitive drum 10, that is, a non-transferred toner, and a charge eliminating device 20 for removing residual charges on the surface of the photosensitive drum 10. Has been.
[0023]
The charging device 12 includes a corona wire 12a and a grid screen 12b, and is connected to a charging voltage generation circuit 112 and a grid bias voltage generation circuit 114, which will be described later with reference to FIG. 2, so that the surface of the photosensitive drum 10 has a predetermined potential. Charge.
[0024]
The developing device 14 holds a two-component developer D in which a non-magnetic toner and a carrier provided with magnetism are mixed at a predetermined ratio at the outer periphery, and a developing bias generation circuit described later with reference to FIG. A developing roller 14 a is provided for attaching toner negatively charged by the developing bias voltage from 116 to the electrostatic latent image formed on the photosensitive drum 10. A predetermined developing bias voltage is also applied to the carrier C and the toner T, that is, the developer D accommodated in the housing 14b by the developing bias voltage applied to the developing roller 14a.
[0025]
Hereinafter, when developing the electrostatic latent image formed on the surface of the photoconductor drum 10, the spikes of carriers formed on the sleeve along the lines of magnetic force generated from the main magnetic pole of the magnetic medium of the developing roller 14a ( In the developing region where the photosensitive drum 10 and the developing roller 14a face each other, the toner adhered by the mirror image force is formed by the potential of the electrostatic latent image on the photosensitive drum 10 and the developing bias voltage. The electrostatic latent image is developed by being moved toward the latent image by the electric field.
[0026]
The transfer device 16 supplies toner from the developing roller 14a of the developing device 14 and develops the toner on the surface of the photosensitive drum 10 by a transfer bias voltage output from a transfer bias generating circuit 118 described later with reference to FIG. The image is electrostatically attracted and transferred to the recording paper. The transfer device 16 is integrally formed with a peeling device 17 that provides a peeling voltage for peeling the toner image on the photosensitive drum 10 together with the paper from the photosensitive drum 10. The peeling device 17 is supplied with a predetermined peeling voltage by a peeling voltage generating circuit (not shown).
[0027]
The cleaning device 18 has a blade 18 a that is pressed against the surface of the photosensitive drum 10 and scrapes off the transferred toner on the surface of the photosensitive drum 10, and scrapes and collects untransferred toner on the surface of the photosensitive drum 10.
[0028]
The static eliminator 20 is lit to provide a predetermined amount of light via a lamp regulator (lighting circuit) (not shown), and erases the remaining potential remaining on the surface of the photosensitive drum 10.
[0029]
Above the photosensitive drum 10, that is, at the top of the apparatus main body, an image reading unit 30 that reads an image of the document D that is a copy target as light brightness / darkness information is disposed.
The image reading unit 30 includes a document table 31 that holds the document D, an illumination lamp 32 that illuminates the document D placed on the document table 31, and a reflector 33 that collects illumination light emitted from the illumination lamp 32 on the document D. The first mirror 34 that guides the reflected light from the document D in a direction parallel to the document table, the second mirror 35 that bends the light reflected by the first mirror 34 by 90 °, and the second mirror 35. The light is further bent by 90 ° and has a third mirror 36 or the like for guiding the light again in a direction parallel to the document table. The illumination lamp 32 and the first to third mirrors 34 and 35 using a scanning motor (not shown). And 36 are moved along the document table 31, and the image of the document D placed on the document table 31 is transmitted to the subsequent CCD sensor 38 as light brightness / darkness information. To do. As is well known, the second mirror 35 and the third mirror 36 are driven by the first mirror 34 at a speed that is half the speed at which the first mirror 34 is moved by a drive mechanism (not shown).
[0030]
In the plane including the optical axis of the light reflected by the third mirror 36, an image forming lens 37 for converging the reflected light from the original D and a CCD for photoelectrically converting the reflected light focused by the image forming lens 37 A sensor 38 is arranged.
[0031]
In the vicinity of the photosensitive drum 10 and at a position where the surface of the photosensitive drum 10 can be irradiated with light corresponding to an original image, the surface of the photosensitive drum 10 to which a predetermined surface potential is applied by the charging device 12 is applied. A laser exposure device 40 for irradiating a laser beam whose light intensity is changed based on the image data of the document image is disposed.
[0032]
The laser exposure device 40 selectively changes the surface potential of the photosensitive drum 10 by irradiating the photosensitive drum 10 to which a predetermined surface potential is applied from the charging device 12 with light corresponding to an image, that is, a laser beam. A semiconductor laser element (not shown) that generates a laser beam for forming an electrostatic latent image on the photosensitive drum 10 by generating a potential difference with the surface potential of the unexposed portion not irradiated with the laser beam, A laser beam output from the semiconductor laser element is deflected in a substantially straight line in a direction parallel to the axis of the photosensitive drum 10, and the laser beam deflected by the polygon mirror device 42 is applied to the photosensitive drum 10. A plurality of mirrors 43, 44, and 45 (in this example, three mirrors) that sequentially irradiate the surface and a semiconductor laser element are emitted. The size of the beam spot of the laser beam is converted into a beam spot corresponding to the resolving power that the apparatus 2 can form an image to form an image on the surface of the photosensitive drum 10 as a straight line parallel to the axis of the photosensitive drum 10 (not shown). An image is exposed on the surface of the photosensitive drum 10 including a plurality of lenses.
[0033]
The positions corresponding to the upstream side of the direction in which the photosensitive drum 10 is rotated and the toner image developed by the developing device 14 is conveyed by the rotation of the photosensitive drum 10 are A3 size, B4 size, Inserts a paper cassette 52 that has a size display mechanism (not shown) that contains standard recording paper (hereinafter simply referred to as paper) such as A4 size or B5 size and displays the size of the paper that it contains. First and second slots 50a and 50b are formed. Each slot 50a, 50b accommodates in a cassette 52,... Based on a size display (not shown) of each cassette set corresponding to the size of the paper accommodated in an arbitrary cassette 52,. Size detection sensors 51a and 51b for informing a printer CPU 106 described later with reference to FIG.
[0034]
Above the first slot 50a, a manual feed passage 53 is formed integrally with the first slot 50a so that a special recording material such as non-standard-size paper or an OHP sheet can be fed. In the manual feed path 53, a paper guide 53a that prevents the paper or the recording material guided through the manual feed path 53 from being inclined with respect to the direction in which the paper or the recording material is conveyed is disposed.
[0035]
The paper guide 53a is movable in accordance with the size (width) of the paper or the recording material, and detects the position of the paper guide 53a, so that the size (width) of the paper or the recording material inserted into the manual feed path 53 is determined. The paper sensor 53b to be detected is formed so that the size of the paper or the recording material can be input.
[0036]
  Between the photosensitive drum 10 and each of the slots 50a and 50b, the first and second sheets are arranged corresponding to the respective slots 50a and 50b, and each sheet is pulled out from an arbitrary cassette 52 inserted into each slot. The second paper feed rollers 54a and 54b and the paper drawn by the paper feed rollers 54a and 54b are transferred to the photosensitive drum 10.ForFirst and second transport rollers 56a and 56b that are sent out are arranged. Note that the sheet and recording material fed by the manual feed path 53 are also guided to the transport roller 56a.
[0037]
Paper transported toward the photoconductive drum 10 between each of the transport rollers 56a and 56b and the photoconductive drum 10 (in this case, including a case of a recording material, the paper will be described as a representative below). Is temporarily stopped to correct the inclination of the sheet with respect to the direction in which the sheet is conveyed, and a registration roller 58 is provided for aligning the leading edge of the toner image on the photosensitive drum 10 with the leading edge of the sheet. The registration roller 58 is formed in a pair with a driven roller 59 that is contacted at one point on the outer peripheral surface and whose axis is arranged in parallel, and is also in contact with each roller via a pressure mechanism (not shown). In FIG. 5, the pressure is slightly applied to each other, so that a propelling force is reliably applied to the paper to be guided to the photosensitive drum 10. The registration roller 58 is rotated at a rotation speed at which the moving speed of the outer peripheral surface is equal to the moving speed of the surface of the photosensitive drum 10.
[0038]
In the vicinity of the registration roller 58, a stop switch 58a for detecting the leading edge of the sheet being conveyed in order to temporarily stop the sheet conveyed toward the registration roller 58 is disposed.
[0039]
At a position corresponding to the downstream side of the rotation direction of the photosensitive drum 10, a toner image formed on the photosensitive drum 10 is transferred, and a conveying belt 60 that conveys the sheet on which the toner is electrostatically attached is conveyed. A fixing device 62 that heats the toner transferred to the paper and presses it against the paper to fix it on the paper, and a paper discharge roller 64 that discharges the paper on which the toner image has been fixed to a paper output tray outside the copying apparatus 2 are arranged. Has been.
[0040]
FIG. 2 is a schematic block diagram showing a control block mainly showing an image forming unit, that is, a printer unit of the laser exposure type copying apparatus shown in FIG.
As shown in FIG. 2, each mechanism of the laser exposure type copying machine 2 is controlled by a CPU 101 as a main control device. The CPU 101 controls reception of image data supplied from a unit via a host device (not shown) such as a personal computer or a transmission line, and an image forming instruction to the image forming unit described below.
[0041]
The CPU 101 temporarily stores ROM (read only memory) 102 in which an initial program for enabling the laser exposure type copying apparatus 2 to warm up and form an image, and numerical data input from a control panel not described in detail. A random access memory (RAM) 103 and an NVM (nonvolatile memory) 104 for semi-permanently holding numerical data set when the apparatus 2 is assembled are connected. Note that the NVM 104 holds check flags indicating whether reset switches or secondary circuit energization switches arranged at various positions of the apparatus 2 are shut off after the warm-up operation.
[0042]
Further, the CPU 101 exposes a laser drive circuit 105 that exposes an image on the photosensitive drum 10 by the laser exposure device 40 and an original image read by the image reading unit 30 from the laser drive circuit 105 toward the photosensitive drum 10. An image processing circuit 106 that processes image data to be processed, and a CCD drive that controls reading of a document image by the CCD sensor 38, converts the document image into an image signal based on a predetermined rule, and outputs the image signal to the image processing circuit 106 A circuit 107 is connected.
[0043]
Next, the printing operation of the laser exposure type copying apparatus shown in FIGS. 1 and 2 will be described in detail.
The photosensitive drum 10 has an outer peripheral surface of, for example, 125 mm / s due to the rotation of a main motor (not shown) that is rotated in response to a motor drive signal output from the paper conveyance control unit 108 in response to a ready signal from the CPU 101. It is rotated so as to have a moving speed of seconds (hereinafter referred to as mm / s).
[0044]
Subsequently, the surface of the photoconductive drum 10 is charged to a surface potential of a predetermined magnitude by supplying the charge by the charging device 12. Specifically, the amount of corona discharge emitted to the surface of the photosensitive drum 10 by corona discharge by the corona wire 12a of the charging device 12 is appropriately adjusted by the grid bias voltage applied to the grid screen 12b.
[0045]
As an example, when a grid bias voltage of approximately −600 V is applied to the grid screen 12b by the grid voltage generation circuit 114 of the process control unit 110, the charging voltage generation circuit 112 (process control unit 110) to the corona wire 12a. In relation to the amount of corona discharge radiation corresponding to the supplied charging voltage, the initial surface potential supplied to the photosensitive drum 10 is set to approximately -600V.
[0046]
Subsequently, under the control of the laser drive circuit 105, the laser exposure device 40 supplies image data to be copied or printed on the surface of the photosensitive drum 10, that is, image information corresponding to the image of the document, or a host device (not shown). A laser beam whose intensity is modulated in accordance with a print signal corresponding to the image signal is emitted.
[0047]
An electrostatic latent image corresponding to the print signal (image data) is formed on the outer peripheral surface of the photosensitive drum 10 by the laser beam irradiation by the laser exposure device 40.
The electrostatic latent image formed in this way is supplied by the developing bias generation circuit 116 of the process control unit 110 by, for example, rotation of the developing roller 14a of the developing device 14 to which a developing bias voltage of −400 V is applied. The toner T is developed. In this development process, the spikes (chains) of chained carriers C formed on the outer peripheral surface of the developing roller 14a along the magnetic lines generated from the main magnetic pole of a magnet (not shown) fixed inside the developing roller 14a. ) In the developing region where the photosensitive drum 10 and the developing roller 14a are opposed to each other due to the mirror image force, the action of an electric field formed by the potential of the electrostatic latent image on the photosensitive drum 10 and the developing bias voltage. As a result of the movement of the toner, the electrostatic latent image formed on the surface of the photosensitive drum 10 is developed. Here, as the developer charged in the developing device 14, a magnetic carrier having an average particle diameter of 65 microns (hereinafter referred to as μm) and a toner having an average particle diameter of 9 μm are preferably 6% by weight. (wt%) mixed is used.
[0048]
In parallel with the formation of the electrostatic latent image on the photosensitive drum 10, the paper feed drive control unit 109 controls the paper size input based on the paper size or image data input from the control panel (not shown). The paper feed roller 54a or 54b corresponding to one of the slots 50a and 50b in which the cassette 52 containing the paper of the specified size is set is rotated so that the paper of the desired size is directed to the registration roller 58. Are transported. Needless to say, paper of any paper size may be fed through the manual feed path.
[0049]
The toner image developed by the developing device 14 is conveyed by the transfer device 16 to which the transfer bias voltage is applied from the transfer bias generating circuit 118 at the transfer position where the photosensitive drum 10 and the transfer device 16 are opposed to each other. The image is guided in advance to the registration roller 58 via the control unit 108, and the leading edge of the image formed on the photosensitive drum 10 and the leading edge of the paper are aligned and transferred onto the paper in order.
[0050]
The toner image transferred to the paper is separated from the surface of the photosensitive drum 10 while being electrostatically adhered onto the paper by the peeling device 17, and is transported to the fixing device 62 by the transport belt 60. As a result, it is fixed on the paper.
[0051]
The sheets on which the toner images are fixed are sequentially discharged to a discharge tray 66 via a discharge roller 64 and stacked.
The photosensitive drum 10 on which the toner image has been transferred to the paper is continuously rotated as the main motor (not shown) rotates, the untransferred toner is removed by the cleaning device 18 and the charge is removed by the charge removing device 20, and then the next image is obtained. Used for formation.
[0052]
In this way, a series of image formation is repeated. When the image data exposed to the photosensitive drum 10 from the laser exposure device 40 by the control of the laser drive circuit 105 is image information corresponding to the image of the document set on the document table 31, it is located near the document table 31. After the presence of a document to be copied is detected by a document detection sensor (not shown) and a document table cover switch (not shown), the illumination lamp 32 is moved by a scan motor (not shown) at a speed corresponding to the reading magnification. Needless to say, the reflected light of the image of the document illuminated by the illumination light is input to the CCD sensor 38.
[0053]
By the way, in a known laser exposure type copying apparatus, a waiting time during which an image cannot be formed is set for a certain period of time after the power of the image forming apparatus is turned on for warming up. This waiting time is requested in the same way as normal warm-up even when the power supply to the apparatus is cut off for some reason during the image forming operation, the cause of the interruption of the power supply is removed, and the power supply is turned on again. Is done. Therefore, when the power supply to the apparatus is interrupted during the image forming operation, the waiting time required until the next image can be formed can be reduced by reducing the time required for warming up. Become.
[0054]
However, the reversal development type image forming apparatus including the laser exposure type copying apparatus of FIGS. 1 and 2 has a toner charging potential and polarity with respect to the charging (surface) potential of the photosensitive drum and the carrier charge as shown in FIG. Depending on the relationship between the charging potential and the polarity, the timing of applying the developing bias voltage or the interruption of the developing bias voltage must be controlled in a specific order or a control pattern according to a time series.
[0055]
Specifically, in the laser exposure type copying apparatus 2 shown in FIGS. 1 and 2, the charging (surface) potential charged on the surface of the photosensitive drum 10 by the charging device 12 is approximately −600 V, and the developing bias voltage. Are set to -400V, respectively. Further, since the charging polarity of the toner is − (minus), the charging polarity of the carrier is + (plus).
[0056]
Hereinafter, as shown in FIG. 3, the region corresponding to the white background on the photosensitive drum 10 is not irradiated with the laser beam from the laser exposure device 40, so that the surface potential charged by the charging device 12, that is, −600 V is applied. Keep it as it is. In this case, since the surface potential is lower than the developing bias potential, the negatively charged toner does not adhere to the photosensitive drum 10. That is, a white background image is formed.
[0057]
Further, the area corresponding to the halftone image on the photosensitive drum 10 is a laser beam in which the density of the laser beam irradiated on the surface of the photosensitive drum 10, that is, the exposure amount per unit area is arbitrarily set according to the image density. As a result, a part of the surface potential is attenuated and changed to, for example, −300V ± 50V. That is, the surface potential of the halftone image area is shifted to 0 V compared to the development bias voltage, and the intermediate potential is changed according to the potential difference between the development bias potential and the surface potential (of the photosensitive drum on which the halftone image is exposed). A predetermined amount of toner is attached to the toned image, and the halftone image is developed.
[0058]
On the other hand, the region corresponding to the black image on the surface of the photosensitive drum 10 is irradiated with a laser beam continuously, so that the surface potential is a potential in the vicinity of the intrinsic residual potential of the photosensitive member on the photosensitive drum 10, for example, It is changed to about -200V. That is, the surface potential of the black image area is greatly shifted to 0 V compared to the developing bias voltage, and a predetermined amount of toner is attached to the black image according to the potential difference between the developing bias potential and the surface potential of the black image area. The black image is developed.
[0059]
By the way, when the energization to the apparatus is interrupted during an image forming operation for some reason, the electrification potential charged on the photosensitive drum is interrupted by the dark attenuation characteristic inherent to the photosensitive drum. The developing bias voltage becomes 0 V almost simultaneously when the energization to the apparatus is cut off, while remaining for a predetermined time after being applied. In this case, when the photosensitive drum is rotated by inertia, a carrier pulling phenomenon in which the carrier in the developer contained in the developing device is electrostatically attracted to the photosensitive drum due to the influence of the residual potential remaining on the photosensitive drum. Arise. When the carrier pulling phenomenon occurs, the carrier attracted to the photosensitive drum is captured by the cleaning device, and then the carrier is damaged on the surface of the photosensitive drum due to the contact between the cleaning device and the photosensitive drum. Therefore, when the power supply to the apparatus is interrupted, the rotation of the photosensitive drum due to inertia is stopped by a brake mechanism (not shown). For this reason, in the reversal development type image forming apparatus, when the energization to the apparatus is interrupted and the energization is started again during the image forming operation, the next time until the remaining potential of the photosensitive drum is surely extinguished. The image forming operation is limited.
[0060]
FIG. 4 shows a warm-up (reset) in the case where the energization of the laser exposure type copying apparatus is cut off during standby or image forming operation after the initial operation of the laser exposure type copying apparatus shown in FIGS. It is a flowchart which shows operation | movement. In FIG. 4, the checking process in the warm-up operation and various processes performed in a predetermined procedure are set for each block such as a signal processing unit including an image reading unit, an image forming unit, and a communication control unit. However, the following description will focus on the image forming unit.
[0061]
As shown in FIG. 4, when the laser exposure type copying apparatus 2 is in a standby state or during an image forming operation, if the power to the apparatus is cut off for some reason and is turned on again, first, it is connected to the CPU 101. All the outputs of each mechanism unit are turned off, and then the initial setting is set. Each task is suspended.
[0062]
Next, the output of paper detection switches (not shown) arranged at various positions inside the apparatus 2 is checked to determine whether or not a paper jam (jam) has occurred inside the apparatus. Here, when a jam is detected, a predetermined symbol mark or a sheet remaining due to a paper jam is removed from a display area of a control panel (not shown) so as to remove a paper remaining inside the apparatus due to a paper jam. A message prompting processing, that is, a service call is displayed.
[0063]
Subsequently, it is checked whether or not the developing device 14 is mounted at a predetermined position. Here, when it is detected that the developing device 14 is not mounted or when the mounting state is not preferable, a message prompting to check the mounting of the developing device 14 or the mounting state of the developing device 14 is displayed on a control panel (not shown). Displayed in the area.
[0064]
Next, a heater (not shown) of the fixing device 62 is turned on. The heater abnormality typified by disconnection of the heater is detected by monitoring the temperature of the fixing device 62. Therefore, after the heater is turned on, the waste toner collected by the cleaning device is accommodated. It is checked whether the container is filled with waste toner, that is, toner full. Here, when toner full is detected, a message or a symbol mark that prompts the user to discard the waste toner in the storage unit, that is, a service call, is displayed on a control panel (not shown).
[0065]
Next, the remaining amount of toner in a toner replenishing portion (not shown) formed integrally with the developing device 14 or detachably attached to the developing device 14 and the amount of toner mixed with the carrier in the developing device 14 at a predetermined ratio are mixed. The ratio, that is, the toner density is checked based on the output of a density sensor (not shown). The toner remaining amount is the number of times the toner is replenished by supplying toner from the toner replenishing unit to the developing device 14 by a toner replenishing mechanism (not shown) when the toner density is lower than a predetermined ratio, that is, when toner empty is detected. If the toner density does not increase even though the predetermined number of times has been exceeded, it is determined that the toner for replenishment in the toner replenishing portion has been exhausted. In this case, a message prompting the toner supply unit (not shown) of the developing device 14 to supply toner, that is, a service call, is displayed in a display area of the control panel (not shown).
[0066]
Hereinafter, at a predetermined timing, the temperature of the fixing device 62 is detected by a temperature sensor (not shown), and it is detected whether the heater is disconnected and whether the heater is heated to a predetermined temperature.
[0067]
Next, whether or not the charging device 12 is mounted at a predetermined position and the abnormality of the charging device 12 are checked.
Specifically, as shown in FIG. 5, charging by the charging device 12 is started 2000 milliseconds after the rotation of the main motor (not shown), the development bias to the developing device 14 is stopped, and the PCC and the discharge lamp are turned on. After 100 milliseconds, it is confirmed that the charging device 12 is mounted by the charging device mounting detection port.
[0068]
Next, after 200 milliseconds elapses, the charging is turned off, and approximately 20 milliseconds (the image exposed at the exposure position from the exposure position on the photosensitive drum 10 to the development position where the developing device and the photosensitive drum 10 are opposed to each other). The development bias is applied after (corresponding to the time to be moved).
[0069]
Thereafter, the development bias is stopped after 346 milliseconds, and the polarity of the development bias is reversed after another 138 milliseconds. At this time, each of the PCC and the charge eliminating lamp is turned off. Further, a main motor (not shown) is rotated reversely for 100 milliseconds at a predetermined timing.
[0070]
The charging check of the charging device generally takes 3 seconds.
When this check detects that the charging device 12 is not mounted or an abnormality of the charging device 12 is detected, a message prompting the user to check whether the charging device 12 is mounted or the charging device 12 is abnormal is displayed in a display area of a control panel (not shown). Is displayed.
[0071]
In addition, when the mounting check of the charging device 12 described above is performed, the carrier pulling described above occurs due to undesired interruption of the power supply to the device 2 as in the case where the image forming operation is executed. The next image forming operation is limited until the remaining potential of the photosensitive drum 10 is surely extinguished.
[0072]
By the way, the check up to this point is similarly performed when the device 2 is energized or when the device 2 is on standby and the device 2 is de-energized for some reason and is energized again. . The result of each check is written in the NVM 104.
[0073]
Next, the time until the next image formation becomes possible when the power supply to the apparatus 2 is interrupted during the image forming operation, that is, the time during which the image forming operation is restricted will be described.
[0074]
As shown in FIG. 6, the time required for each check other than the initial setting and the charging device 12 check described above is approximately 0.1 seconds. Further, the time required for the mounting check of the charging device 12 is approximately 3 seconds as described above with reference to FIG. On the other hand, as already described, when the power supply to the apparatus 2 is interrupted during the image forming operation, the carrier pulling phenomenon shown in FIG. Until the image disappears, the next image forming operation is limited. The time during which the image forming operation is restricted is approximately 20 seconds as shown in FIG. 6 although it is governed by the dark decay characteristics of the photosensitive drum 10.
[0075]
Therefore, even when the power supply to the device 2 is cut off by identifying the case where the power supply to the device 2 is cut off during the image forming operation and the case where the check for the charging device 12 is performed, the It is possible to return to the standby state in a short time. Here, the operation state of the device 2 immediately before the energization of the device 2 is interrupted, that is, whether or not a predetermined time has elapsed since the device 2 is in the image forming operation or the charging device 12 is checked is written in the NVM 104. It is easily determined based on the operation history of each mechanism of the device 2.
[0076]
Therefore, as shown in FIG. 4, whether the image forming operation has been performed when a predetermined time has passed since the charging device 12 was checked or the power supply to the device 2 was cut off is written in the NVM 104. If the device 2 is in a standby state, the check for the charging device 12 is deleted, and even if the power supply to the device 2 is cut off, the device 2 is in a short time. It becomes possible to return to the state. In addition, as an event similar to when the power to the device 2 is cut off, a safety switch for protecting a user who is placed in various positions on the exterior cover or the device 2 not described in detail of the device 2 is turned off. There is a reset action. For this reason, when the exterior cover is opened or when the safety switch is turned off, the device 2 is identified by identifying when the device 2 is waiting based on the data written in the NVM 104. In the case of waiting, it is possible to return to the waiting state in a short time.
[0077]
As described above, when the power supply to the device 2 is cut off, the operation state of the device 2 immediately before the power supply to the device 2 is cut off is identified on the basis of the data written in the NVM 104. It is possible to shorten the warm-up time for conditions where there is no risk of occurrence.
[0078]
Thereby, for example, when the device 2 is on standby, the device 2 is energized again even if the exterior cover is accidentally opened by the user or the power switch is inadvertently turned off. The warm-up can be completed in a short time. Therefore, the user is not unnecessarily waited, and the use efficiency of the apparatus is improved. This reduces copying costs (personnel and overhead).
[0079]
Also, for example, when assembling the device 2, when energizing is intentionally interrupted in a series of operations, the next operation (process) can be performed after a short waiting time without causing carrier pulling. Work efficiency is improved. This reduces the assembly cost of the device.
[0080]
【The invention's effect】
As described above, the image forming apparatus according to the present invention determines the operating state of the apparatus immediately before the power supply to the apparatus is cut off based on the data written in the nonvolatile memory, and the apparatus causes carrier pulling. When there is no fear of waiting, it is possible to return to the waiting state in a short time. This prevents the user from waiting undesirably and improves the use efficiency of the apparatus. Also, for example, when assembling the device 2, when energizing is intentionally interrupted in a series of operations, the next operation (process) can be performed after a short waiting time without causing carrier pulling. Work efficiency is improved.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a laser exposure type copying apparatus to which an embodiment of the present invention is applied.
2 is a block diagram centering on an image forming unit of the laser exposure type copying apparatus shown in FIG. 1;
FIG. 3 is a schematic view showing development bias, toner and carrier movement in the laser exposure type copying apparatus shown in FIGS. 1 and 2;
4 is a flowchart showing an example of control of an initial operation of the laser exposure type copying apparatus shown in FIGS. 1 and 2. FIG.
FIG. 5 is a timing chart showing an example of a charging device mounting check of the laser exposure type copying apparatus shown in FIGS. 1 and 2;
6 shows an image forming operation performed in order to prevent carrier pulling that may occur when the laser exposure type copying apparatus shown in FIGS. 1 and 2 is turned off during the image forming operation. The timing chart explaining the time to be limited.
[Explanation of symbols]
2 ... Laser exposure type copying machine (image forming machine)
10 ... photosensitive drum,
12 ... charging device,
14: Developing device,
16: Transfer device,
18 ... cleaning device,
20 ... neutralizing device,
30: Image reading unit,
31 ... manuscript table,
32 ... Lighting lamp,
37 ... imaging lens,
38 ... CCD sensor,
40: Laser exposure apparatus,
52… cassette,
58 ... Registration roller,
58a: Stop switch,
60 ... conveyor belt,
62 ... fixing device,
101 ... CPU,
102… ROM,
103 ... RAM,
104 ... NVM,
105 ... Laser drive circuit,
106 Image processing circuit,
107 ... CCD drive circuit,
108... Paper conveyance control unit,
109 ... Paper feed drive control unit,
110 ... process control unit,
112 ... charging voltage generation circuit,
114... Bias voltage generation circuit,
116... Development bias voltage generation circuit,
118: Transfer bias generation circuit.

Claims (6)

An image forming means for forming an image on the image carrier;
In the reversal development method, a developing means for supplying a developer to the image formed on the image carrier by the image forming means to form a developer image;
Once conductible is when it is interrupted, the next is energized while the developer image is formed on the image carrier by the developing unit, to the residual potential of the image bearing member is eliminated rotation between the Kizo carrier with stops, when the formation of the developer image onto the image carrier by the developing unit power is interrupted in the standby state is stopped, it is then energized Once the, reference is operation history stored in advance in the storage means, it said if it is determined in the standby state, the upper in a shorter wait time than the time until the residual potential of the image carrier disappears Symbol Control means for permitting image formation by the image forming means;
An image forming apparatus comprising: An image forming means for forming an image on the image carrier;
In the reversal development method, a developing means for supplying a developer to the image formed on the image carrier by the image forming means to form a developer image;
Even when the energization is interrupted, the data can be retained, and the developing unit and the image forming unit immediately before the energization is interrupted are checking whether the image carrier is charged. Data holding means for holding an operating state indicating whether a predetermined time has passed since
If the power supply is cut off, based on the data of the operating state of the developing means and the image forming means said data holding means holds, then when it is energized, the image formation by said image forming means, the Control means for permitting in association with the time until the residual potential of the image carrier disappears ;
An image forming apparatus comprising: An image forming means for forming an image on the image carrier;
In the reversal development method, a developing means for supplying a developer to the image formed on the image carrier by the image forming means to form a developer image;
A data holding means for holding the operating state of the developing means and the image forming means even when the power is cut off;
The data on the operating states of the developing unit and the image forming unit immediately before the energization held by the data holding unit is cut off has stopped the formation of the developer image on the image carrier by the developing unit. A control means for permitting image formation by the image forming means by omitting a check on charging of the image carrier when the power is turned off next time when the power is cut off in a standby state;
An image forming apparatus comprising: When the energization to the image forming unit is interrupted, the control unit is configured to operate the energizing unit immediately after the energization to the image forming unit is interrupted. 4. The image forming apparatus according to claim 3, wherein an image forming operation by the image formation is prohibited for a time until the residual potential of the image carrier disappears . An image carrier that holds an image by selectively changing the potential distribution while being charged to a predetermined potential; and
Charging means for charging the image carrier to a predetermined potential;
A reversal developing type developing means that holds a developer and a developer holding member that imparts triboelectric charge to the developer, supplies the developer to an image held by the image carrier, and forms a developer image;
If the energization is again energized immediately after being cut off, just before the current is cut off, based-out on whether charging to said image bearing member has been continued by the charging means, above the image carrier When the energization is interrupted while the developer image is formed, the rotation of the image carrier is stopped until the remaining potential of the image carrier disappears at the next energization. When the power supply is shut off in a standby state in which formation of the developer image on the image carrier by the developing means is stopped, the operation stored in the storage means in advance when the power is turned on next time. Image formation control means for permitting image formation by the image forming means in a standby time shorter than the time until the residual potential of the image carrier disappears when the history is referred to and the standby state is determined. When,
An image forming apparatus comprising: An image carrier that holds an image by selectively changing the potential distribution while being charged to a predetermined potential; and
Charging means for charging the image carrier to a predetermined potential;
A reversal developing type developing means that holds a developer and a developer holding member that imparts triboelectric charge to the developer, supplies the developer to an image held by the image carrier, and forms a developer image;
When the energization is interrupted and then energized again immediately after the energization is interrupted, the fact that charging of the image carrier by the charging means has been stopped immediately before the energization is interrupted is based on the operation history stored in advance in the storage means. when detecting includes an image formation control means for managing to minimize the time the operation of the image carrier is stopped,
An image forming apparatus comprising:

Images