JPH07129035A - Image forming device and control method therefor - Google Patents

Abstract

PURPOSE:To provide an image forming device capable of more large amount of printing output by reducing the quantity of toner consumed in a nonimage region. CONSTITUTION:In this laser printer 2, a discharging lamp 28 is turned on before a photoreceptor drum 12 is rotated and a developing bias voltage is applied to a developing device 22 and erasing beam is provided from an exposing device 30 at the same time of electrifying a photoreceptor drum 12 by an electrifier 20. Moreover, when the irradiation of an image forming beam provided from the exposing device 30 is ended, the electrification of the photoreceptor drum 12 by the electrifier 22 is completed, and when the electrification is completed and the region of the photoreceptor drum 12 approaching the electrifier 20 passes the developing device 22, the application of the developing bias voltage is stopped, further, a motor is stopped based on an idle running time that the region is carried up to the vicinity of the discharge lamp 28 by the inertia of the motor, so that all image formation can be completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image based on image data by an electrostatic photography process, developing the image with a heat-melting toner, and outputting the image onto a sheet, and a control method for the image forming apparatus. Regarding

[0002]

2. Description of the Related Art In a reversal development printer device using an electrostatic photography process, for example, a printer device using a two-component reversal development method, a photosensitive drum is generally about -500 volts to -700. Charged by the bolt. By irradiating the photoconductor drum with light, an electrostatic latent image is formed in the region where the light is radiated.

This electrostatic latent image is developed by supplying only toner through a developing device containing a two-component developer consisting of toner and carrier. At this time, in order to prevent the carrier from being attached to the photosensitive drum from the developing device, a bias voltage of approximately -300 to -500 V is applied to the developing roller of the developing device prior to charging the photosensitive drum. It In order to prevent the carrier from being attached to the photosensitive drum, this developing bias voltage is similarly applied for a predetermined time even after the charging of the photosensitive drum is completed. On the other hand, it is known that when a developing bias is applied to the developing roller of the developing device and the charging of the photosensitive drum is completed, toner adheres to the surface of the photosensitive drum. These toners, that is, the toners (waste toners) not used for the image are collected in a waste toner tank arranged near the photosensitive drum.
Incidentally, in many printer devices today, the photosensitive drum, the developing device, and the waste toner tank are integrally formed as a process unit.

[0004]

By the way, when developing a latent image with a two-component developer, when the photosensitive drum is charged and the developing bias voltage is not applied,
As described above, while the carrier is attached to the photosensitive drum, while the developing bias voltage is applied and the photosensitive drum is not charged, as described above, undesired toner is applied to the photosensitive drum. Is attached.

As described above, the undesired toner adheres to the photosensitive drum at the time of non-image formation, that is, when the charging of the photosensitive drum is started or ended. There is a problem that the number of prints that can be printed is reduced. This, at the same time, causes a rapid increase in waste toner. When the waste toner is increased rapidly, there is a risk that the process unit may have to be replaced or the mechanism for collecting the waste toner may be damaged despite the unused toner remaining. There is a problem. An object of the present invention is to provide an image forming apparatus that enables more print output by reducing the amount of toner consumed in the non-image area.

[0006]

SUMMARY OF THE INVENTION The present invention has been made based on the above-mentioned problems, and includes a rotatably formed photoconductor, driving means for rotating the photoconductor, and a predetermined unit on the photoconductor. A charging means for supplying an electric potential, an exposing means for irradiating the photoconductor with light, a developing means for developing a latent image formed on the photoconductor via the exposing means, and a charging means for the developing means. Bias means for supplying a bias potential having a polarity to reduce the effective value of the potential provided to the photoconductor, static erasing means for erasing the potential provided to the photoconductor, and instructing the drive means to start driving. And an instruction means for driving the photoconductor by the driving means via the instruction means, the destaticizing means is energized prior to the driving of the photoconductor so that the rotation speed of the photoconductor is predetermined. Up when the value is reached The charging means and the exposing means are energized, the exposing means is stopped when the output of the charging means reaches a predetermined value, and the charging means is stopped when the potential supply from the charging means is started. Immediately before the area of the photoconductor that has been in close proximity is opposed to the developing means, the bias means is energized, and the exposure means is activated at substantially the same timing as the bias voltage is energized via the bias means. The intensity is modulated according to the image information, the charging means and the exposing means are stopped when the image information supplied to the exposing means is completed, and the charging is performed when the potential supply from the charging means is completed. The bias means is stopped at the time when the driving means is energized until the area of the photosensitive member which is close to the means is opposed to the developing means, and the potential is supplied from the charging means. And a control means for stopping the driving means at a predetermined timing so that the driving means is completely stopped in a state where the area of the photoconductor which has been close to the charging means at the time of completion is opposed to the discharging means. An image forming apparatus having the above is provided.

Further, according to the present invention, the photosensitive member rotatably formed, the driving means for rotating the photosensitive member, the photosensitive member integrally formed with the photosensitive member, and detachable integrally. Charging means for supplying a predetermined potential on the photoconductor, exposure means for irradiating the photoconductor with light, integrally formed with the photoconductor and the charging means, and detachable integrally Developing means for developing the latent image formed on the photoconductor via the exposing means, and a bias potential having a polarity for reducing the effective value of the potential provided to the photoconductor from the charging means to the developing means. Biasing means for supplying,
A charge removing unit that is integrally formed with the photoconductor, the charging unit, and the developing unit and is detachably attached to erase the potential provided to the photoconductor; and an instruction to start driving to the drive unit. And an instruction means for performing the driving of the photoconductor by the driving means via the instruction means,
The charge eliminating means is energized prior to the driving of the photoconductor, the charging means and the exposing means are energized when the rotation speed of the photoconductor reaches a predetermined value, and the output of the charging means is a predetermined value. When the exposure means is stopped, the exposure means is stopped, and at the time when the supply of the electric potential from the charging means is started, the region of the photoconductor which is close to the charging means is immediately before facing the developing means. The bias means is energized, and the exposure means is intensity-modulated according to the image information at substantially the same timing as the bias voltage is energized via the bias means, and the image information supplied to this exposure means ends. At that time, the charging means and the exposing means are stopped, and when the supply of the electric potential from the charging means is completed, the area of the photoconductor which is close to the charging means is opposed to the developing means. The biasing means is stopped when the driving means is energized, and the area of the photoconductor which is close to the charging means at the time when the supply of the electric potential from the charging means ends is opposed to the discharging means. And a control unit that stops the driving unit at a predetermined timing so that the driving unit is completely stopped in this state.

Further, according to the present invention, the photoconductor, the driving means for rotating the photoconductor, the charging means for supplying a predetermined potential to the photoconductor, and the photoconductor charged through the charging means. Exposure means for irradiating light to a latent image to form a latent image, developing means for developing the latent image formed via the exposure means, bias means for providing the developing means with a predetermined bias potential, and In an image forming apparatus including an erasing means for erasing the electric potential provided via the charging means, T _E0 is a timing at which the charge eliminating means is energized, T _E1
Is the timing for stopping the charge eliminating means, T _M0 is the timing for _{activating the} driving means, T _M1 is the timing for stopping the driving means, _TL0 is the timing for _{activating the} exposing means, and Y _L1 is the above. Timing of stopping the exposure means,
T _C0 is the timing when the charging means is energized, T _C1 is the timing when the charging means is stopped, T _B0 is the timing when the biasing means of the developing means is energized, and T _B1 is the biasing means stopped. At the timing, T _D0 is the time when the surface of the photoconductor charged through the charging means reaches the developing position of the developing means, and T _D1 is the time when the surface of the photoconductor after the charging from the charging means is finished. When the developing position of the above-mentioned developing means is reached, T _11
Is the interval between T _M0 and T _C0 and T ₁₂ is T _C0 and T _B0
, T ₁₃ is the interval between T _D0 and T _B0 , T ₁₄ is the interval between T _B1 and T _D1 ,
₁₅ for the interval between T _B1 and T _M1 , T ₁₆ for T _E0 and T
When the interval between the _M0, the T ₁₈ interval between T _E1 and T _M1, and, in T _11, a minimum stabilization time of the drive means, the T _{12, the} T _{D0, T 13, 0, At T 14} ,
0.02 seconds or less, the T _16, a time until the brightness of the static eliminating light from the charge removing means is stabilized, enter each as a parameter, the control of the image forming apparatus characterized by setting the T _M1 A method is provided.

[0009]

According to the present invention, when the driving of the photoconductor is instructed, the charge eliminating means is energized prior to the driving of the photoconductor, and the rotation speed of the photoconductor reaches a predetermined value. The charging means and the exposing means are energized at the same time, the exposing means is stopped when the charging means and the output reach a predetermined value, and the charging means is started when the potential supply from the charging means is started. The biasing means is biased immediately before the region of the photoconductor that has been close to the developing means is opposed to the developing means, and the exposure means is approximately at the same timing as the bias voltage is biased via the biasing means. Is intensity-modulated according to the image information, the charging means and the exposing means are stopped at the time when the image information supplied to the exposing means is finished, and the voltage is increased at the time when the potential supply from the charging means is finished. When the biasing means is stopped at the time when the driving means is energized until the area of the photoconductor that has been close to the charging means faces the developing means, and when the supply of the potential from the charging means ends. Then, the drive means is controlled so that the drive means is completely stopped in a state where the region of the photoconductor which has been close to the charging means faces the charge removing means. Therefore, the amount of toner consumed in the non-image area can be reduced, and an image forming apparatus that enables more print output can be provided.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows an image forming apparatus, that is, a laser beam printer in which an embodiment of the present invention is incorporated.

The image forming apparatus, that is, the laser printer 2 includes a photosensitive drum 12 which is rotatable in the direction of an arrow and is formed in a cylindrical shape, and forms an image based on image data supplied from an external device. A printer main body 100 that feeds a transfer target material, that is, a sheet P toward the unit 10 and the process unit 10, and outputs an image formed through the process unit 10 as a print output (hard copy).
have.

The process unit 10 is formed so as to be attachable to and detachable from the printer body 100 which outputs an image formed through the unit 10. In the printer body 100, first and second cassettes (to be described later) that accommodate a sheet P for transferring an image formed via the photoconductor drum 12 are detachably formed.

Around the photoconductor drum 12 in the process unit 10, a charging device 20 for charging the photoconductor drum 12 with a predetermined electric charge and a photoconductor drum 12 are opposed to each other.
A developing area 22a is formed between the developing device 22 and the photosensitive drum 12, and the electrostatic latent image formed on the photosensitive drum 12 is supplied with heat-melting toner to develop the developing device 22, which faces the photosensitive drum 12. The photosensitive drum 12 or process unit
A transfer region 24a is formed between the transfer device 24 and the transfer drum 24, which transfers the toner image formed on the photosensitive drum 12 to the paper P fed from a paper cassette (described later). A cleaning device 26 for scraping off the residual toner, and a charge eliminating lamp 28 for stabilizing the amount of electric charges charged on the photosensitive drum 12 are arranged in order along the rotation direction.

The photosensitive drum 12 is rotated at a rotation speed corresponding to the recording density, which will be described later, that is, the number of laser beams emitted from the laser exposure device 30 per inch through a motor (not shown).

The charging device 20 uses a scorotron in which a grid screen is arranged between the corona wire and the photoconductor drum 12 and the amount of electric charge directed to the photoconductor drum 12 can be limited.

The developing device 22 includes a developer in which a toner (not shown) and a carrier (not shown) are mixed, and a magnet roller 22 which conveys the developer toward the photosensitive drum 12.
By selectively supplying toner to the electrostatic latent image formed on the photoconductor drum 12 including b, the image data to be output is developed. A toner cartridge (not shown) can be attached to and detached from the developing device 22, and the toner consumed by developing the electrostatic latent image is replenished according to the consumed amount.

As the transfer device 24, a corotron that can reliably attract the toner image on the surface of the photosensitive drum 12 to the paper P is used. The cleaning device 26 includes an elastic blade 26a that contacts the photosensitive drum 12 and a toner collecting case.
26b, is developed by the developing device 22, and is transferred to the transfer device 24.
The remainder (residual toner) of the toner image transferred onto the paper P is scraped off from the photosensitive drum 12 and collected.

An exposure window 14 for irradiating the photoconductor drum 12 with a laser beam from an exposure device (which will be described later) is formed between the charging device 20 and the developing device 22 of the process unit 10.

An exposure window 14 of the process unit 10, that is, a position capable of irradiating the laser beam toward the photosensitive drum 12, includes a laser diode (not shown) and exposes the laser beam whose intensity is modulated based on image data to be output. A laser exposure device 30 that irradiates the body drum 12 is arranged.

The laser exposure device 30 is, for example, 600 [d
The laser beam generated from a laser diode (not shown) formed so as to provide a recording density of [pi = dot per inch] is transmitted through the focusing lens 32 to a beam spot corresponding to a predetermined beam spot, that is, 600 [dpi]. Is given and is sequentially deflected in the axial direction of the photosensitive drum 12 by the deflecting device, that is, the rotary polygon mirror 34. Rotating polygon mirror 34
The laser beam deflected through is focused by the fθ lens 36 so as to have the same beam spot at any position on the photosensitive drum 12, is reflected by the exit mirror 38, and is passed through the exposure window 14 through the exposure window 14. The photoconductor drum 12 is irradiated. Needless to say, the rotation speed of the rotary polygon mirror 34 corresponds to 600 lines / inch.

A cassette 1 attached to the printer body 100
First and second take-outs for drawing out the papers P one by one from either one of the cassettes 02 and 122 and the process unit 10 and feeding the drawn-out papers P to the transfer area 24a. Rollers 104 and 124, first and second sheet take-out guides 106 and 126, first and second conveyance roller pairs 108 and 128, first and second sheet conveyance guides 110 and 130, and feed from respective cassettes. A pair of aligning rollers for removing the inclination of the conveyed paper P during conveyance, and for aligning the position of the paper P with the image formed on the photosensitive drum 12 of the process unit 10.
150, a pre-transfer paper guide 152 that guides the leading end of the paper P toward the photoconductor drum 12, and a transfer guide roller 154 for surely bringing the paper P into close contact with the photoconductor drum 12
Etc. are arranged in order.

In the vicinity of the cassettes 102 and 122, a paper detection switch (not shown) for detecting the presence or absence of the paper P stored in each cassette, and the size of the paper P stored in each cassette (Actually, the identification code displayed on the cassette) (not shown) Paper size detection switch, and that each cassette is installed in the printer 2 (not shown) Cassette detection switch Are arranged.

A manual paper feed guide 156 capable of feeding papers P of various sizes is incorporated on the side of the second paper feed guide 130 independently of the cassettes 102 and 122. The paper P inserted into the printer 2 via the manual paper feed guide 156 is guided to the second paper transport guide 130,
It is used similarly to the paper P fed from the cassettes 102 and 122.

The space between the cassettes 102 and 122 is
Process unit control circuit board for controlling the process unit 10 (described later) (process unit control unit 200)
, And controls all electronic circuits or electrical components in the printer 2 (described later) Main control circuit board (main control unit 300)
However, it is removably incorporated through a housing (not shown) corresponding to each substrate.

The paper P on which the toner image has been transferred, which is on the side of the process unit 10 and which has passed through the transfer area 24a and the side opposite to the transfer guide roller 154, that is, the transfer area 24a.
A paper guide 158 for conveying the paper P on which the toner image is transferred, and a fixing device 160 for fixing the toner of the toner image transferred on the paper P to the paper P by heating and pressing are arranged in the direction in which the toner image is transferred. Has been done.

The fixing device 160 includes a heating roller 162 having a heater 164 installed therein, a pressure roller 166 extending along the axis of the roller 162, and a pressure roller 166 arranged to face the roller 162 so as to come into pressure contact with the roller 162. And housing 166 for housing 166.

The housing 160a is formed so that heat from the heater 164 does not escape in order to secure a temperature that enables good fixing. The heating roller 162 is a hollow cylinder made of a metal having good thermal conductivity, such as aluminum, and has a coating (not shown) on its surface to prevent adhesion of melted toner. There is. The pressure roller 166 has an elastic layer, for example, a rubber layer, formed on the surface. On the outer peripheral surface of the heating roller 162, dirt on the roller surface, that is, the adhered toner or the paper P
Cleaner 162 for removing fine powder and dust from
a is pressed along the axis. A thermistor 162b for detecting the temperature of the outer peripheral surface of the roller 162 is also located on the outer peripheral surface of the heating roller 162, and the heater 164 is controlled based on the temperature of the outer peripheral surface of the roller 162 detected via the thermistor 162b. Therefore, the outer peripheral surface of the roller 162 is maintained at the optimum temperature.

In the direction in which the paper P on which the toner image is fixed via the fixing device 160 is sent out, that is, in the downstream of the fixing device 160, there is provided a first discharge roller pair 170 for discharging the paper P to the outside of the printer 2, A switching gate 172 that guides the paper P sent from one discharge roller pair 170 to a reversing path 174 for turning the inside and outside of the paper P, and the paper P that has been reversed through the switching gate 172 and the reversing path 174 to the printer. The second discharge roller pair 176 is disposed to discharge the toner to the outside. At a position where the sheet P, which is urged through the first pair of discharge rollers 170 and passed through the switching gate 172, is discharged,
The first stock tray 178 is again the switching gate 172
The second stock tray 180 (a part of the outer cover of the printer body) is located at a position where the paper P that is branched through the reverse path 174 and the second discharge roller pair 176 is discharged. , Respectively.

2 and 3, the connection between the process unit controller incorporated in the laser printer shown in FIG. 1 and peripheral electronic circuits and electrical components, and the main controller and peripheral electronic circuits and Connections with electrical components are shown.

According to FIG. 2, the process unit controller 2
00 is the process control circuit 210 and the process control circuit 2
Electronic circuits (including connection circuits) connected to 10, eg,
A high voltage generation circuit 220, an electrical component drive circuit 230, a laser exposure control circuit 240 for energizing the laser exposure apparatus 30, and a plurality of I / O ports for receiving signals from many switch groups and sensor groups. It includes (unsigned) and multiple connection circuits (unsigned). The respective circuits and devices are connected to each other via an internal bus line 260. Further, the process control circuit 210 is a main control circuit 31 for controlling the printer main body 100 (shown in FIG. 3 described later).
Like 0, it has a CPU 212, a ROM 214, a RAM 216, and a non-volatile memory 218.

The process control circuit 210 includes a printer body.
+5 from power supply located at 100 (unsigned)
The voltages of [V] and +24 [V] are input. +5
The voltage of [V] is used as a signal in the process unit 10 and the process unit controller 200. A voltage of +24 [V] is supplied to the process control circuit 210 via a plurality of cover switches (not shown) arranged on all exterior covers (which can be opened and closed by the user) of the printer main body 100 to control the printer. Circuit 210 and (connected to control circuit 210)
It is supplied to each electric component through an electronic circuit including a connection circuit. The voltage of +24 [V] is 100
Since any one of the outer covers is shut off when it is opened, the user can be protected even if the cover is opened by the user.

The ROM 214 contains rules for operating the printer body 100, such as the timing of energizing the charging device, the amount of electric charge radiated from the charging device 20 toward the photosensitive drum 12, or the paper shape. A print start position (laser exposure start position with respect to the length of the photoconductor drum 12) defined according to the above is stored in advance.

The high voltage generating circuit 220 generates a high voltage applied to the charging device 20 (not shown) and a developing bias applied to the developing roller 22a of the developing device 22 (not shown). ) Generates a high voltage that is applied to the developing bias generator and transfer device 24.
A transfer voltage generating circuit (not shown) is included, and a predetermined high voltage is supplied to each device via a connection (not shown).

The electric component drive circuit 230 includes a motor drive circuit (not shown), a lamp lighting circuit (not shown),
Further, a solenoid drive circuit (not shown) is further connected. The electrical component drive circuit 230 energizes, for example, the static elimination lamp 28, the main motor, the sheet feeding solenoid, the aligning solenoid, the toner replenishing solenoid, the gate solenoid, etc. independently or at the same time via a connection (not shown).

The laser exposure control circuit 240 is a semiconductor laser.
242, a motor 244 for energizing the rotary polygon mirror 34, a laser driver 246a for energizing the semiconductor laser, a laser modulation circuit 246b for intensity-modulating the laser beam output from the laser, a laser light detection sensor 248, and the like. An electrostatic latent image is formed on the photoconductor drum 12 by intermittently generating a laser beam based on image data externally supplied via the printer body 100.

To each of the plurality of I / O ports and the connection circuit, a toner sensor (not shown), a PE switch for detecting the presence or absence of paper, a size switch for detecting the size of the paper, and the detection of the mounting of the cassette are detected. A size switch, a discharge switch (not shown), an aligning switch (not shown), and the like are connected, and the operation status of each part in the printer main body 100 or the process unit 10 is input.

According to FIG. 3, the main control unit 300 has the CPU 3
A memory unit 320 having 12 and a main control circuit 310 for controlling the printer body 100, a ROM 322, a RAM 324, an expansion memory 326, a nonvolatile memory 328, and the like, a ROM 3
22, RAM 324, expansion memory 326, non-volatile memory 328
And a data expansion unit 330 including a video RAM 332, a parallel-serial conversion circuit 334, and the like. The main controller 300 is also shown in FIG.
The printer interface 340 for matching the conditions of signal transfer between the process unit control circuit 210 and the main control circuit 310 shown in FIG. 2, an external device for supplying image data, for example, between the host computer and the main control circuit 310. Host interface that matches the conditions for passing signals 35
0 and a plurality of connection circuits or input / output circuits 362, 36
It has 4, 366, etc. The respective circuits and elements are connected to each other via a bus line 370.

The main control circuit 310, that is, the CPU 312, is a ROM
The printer main body 100 is initialized (initialized) based on a program stored in advance in the 322, and the process unit is based on the input image data.
Energize 10 to output the desired image.

The ROM 322 has a personal identification number to be collated when data is changed, and print data necessary for outputting an image based on image data supplied from an external device, that is, a host computer, for example, a leading edge. The margin, the left and right margins, the paper shape, and the like are stored.

The RAM 324 temporarily stores the image data supplied from the host computer and is also used as a buffer for data processed through the main control circuit 310.

The expansion memory 326 is used to temporarily store a large amount of data supplied from the host computer that cannot be accommodated in the RAM 324. The non-volatile memory 328 is the time when the printer main unit 100 is operated.
The (total number of prints) and the time when the process unit 10 is used (the number of prints per unit) are sequentially stored.

The video RAM 332 has a bit image.
The expanded parallel data is stored in (print data for print output). Parallel-serial conversion circuit 3
Reference numeral 34 converts the parallel data stored in the video RAM 332 into serial data used for intensity modulation of the laser beam output from the laser exposure device 30 toward the photosensitive drum 12.

The printer interface 340 is used for matching the conditions of data transfer between the data expansion unit 330 and the process unit 10 (printer unit), and the image data converted into serial data is laser exposure apparatus.
Send to 30.

The host interface 350 has a serial transfer line 352 and a parallel transfer line 354, and matches the conditions for data transfer according to the type of data to be transferred.

The input / output circuit group (without reference numeral) is an external RO.
M, for example, connection circuits 362 and 364 for connecting an IC card or the like in which character fonts are stored, an operation panel that receives an input from an operation panel (not shown) and turns on an LED or the like incorporated in the operation panel It has a control circuit 366 and the like, and operates a device added to the printer main body 100 via each port or circuit.

The internal bus line 370 is connected to the main control circuit 310,
The ROM 322 and the RAM 324, the video RAM 332, the printer interface 340, the host interface 350, and the input / output circuit group are connected to each other and are used for transferring data between them.

Next, the operation of the printer body 100 of the present invention will be described. The printer main body 100 is initialized (initialized) according to a program stored in the ROM 322 when a main switch (not shown) is turned on.

Image data supplied from an external device such as a word processor or a host computer via the host interface 350 is sequentially stored in the RAM 324 (and the expansion RAM 326 depending on the amount of data).

More specifically, by initializing the printer main body 100, the RAM 324 (and the expansion RAM 326) becomes
It is maintained in a state of waiting for input of image data from the host computer.

The image data input to the RAM 324 is R
Based on the paper shape and the size of each margin stored in the OM 322, it is expanded in the RAM 324 (or expansion RAM 326), converted into parallel data, and converted into the video RAM 3
Supplied to 32. The parallel data stored in the video RAM 332 is converted into serial data through the parallel-serial conversion circuit 334, the timing is adjusted through the main control circuit 310, and the serial data is supplied to the laser exposure apparatus 30.

On the other hand, in accordance with the input data or the control signal input from the operation panel, the paper cassette containing the paper P suitable for printing the data to be output is selected, and the toner to be described later is selected. Waiting for image transfer.

In parallel with this, the photosensitive drum 12 is rotated at a desired rotation speed, and a desired potential is applied through the charging device 20. At the same time, the selected paper P is taken out via the take-out roller and the paper guide corresponding to each, and is conveyed to the aligning roller pair 150.

The image data converted into serial data is supplied to the laser exposure device 30 according to a vertical synchronizing signal from a vertical synchronizing control circuit (not shown), and the intensity of the laser beam generated from the laser is changed according to the data. Change continuously. The laser beam whose intensity is continuously changed according to the image data is successively transmitted to the photosensitive drum 12 and converted into an electrostatic latent image. The image converted into a latent image on the photoconductor drum 12 is guided to a developing area facing the developing device 22 as the photoconductor drum 12 moves, and toner is selectively applied to the latent image via the developing device 22. It is supplied and developed, and is conveyed with the rotation of the photosensitive drum 12, and the transfer device 24
It is conveyed to the transfer area facing.

On the other hand, with respect to the paper P temporarily stopped by the aligning roller pair 150, the leading edge of the image and the leading edge of the paper P are aligned according to a vertical synchronizing signal from a vertical synchronizing circuit (not shown), and the photosensitive drum Sent to 12. Therefore, the toner image on the photoconductor drum 12 and the paper P are attracted (adhered) to the photoconductor drum 12 by the electric charge remaining on the photoconductor drum 12 at a predetermined timing. After this, the photosensitive drum 12 and the paper P have already been transferred (for latent image formation).
A charge having the same polarity as the charge applied to the photoconductor drum 12 is supplied to the photoconductor drum 12 from the transfer device 24, and the toner image on the photoconductor drum 12 is transferred to the paper P.

The paper P on which the toner image is placed is fixed by the fixing device 160.
The toner image having a heat melting property is melted, and the toner image is fixed (fixed) on the paper P. On the other hand, the photoconductor drum 12 from which the paper P and the toner image have been separated is further rotated, the charge distribution on the surface is returned to the initial state by the cleaning device 26, and the photoconductor drum 12 is used for the next image formation.

The paper P on which the image data is output by the series of image forming processes described above is sequentially stocked in the stock tray 178 or 180 to be discharged through the switching gate 172.

Here, the charging of the photosensitive drum 12 and the application of the developing bias to the developing device 22 will be described in detail. FIG. 9 shows a conventionally known one-sheet print.
(When the print start signal is input, the photosensitive drum 12
Is rotated and the rotation of the photoconductor drum 12 is stopped after printing on one sheet is finished. Hereinafter, referred to as intermittent printing), the charging and developing device for the photoconductor drum 12
The timing of applying the developing bias to 22 is shown.

According to FIG. 9A, a print start signal (not shown) is input, and a main motor (not shown) for rotating the photosensitive drum 12 at a predetermined speed is energized at T _M0 .
The main motor, that is, the photosensitive drum 12 is rotated for at least the time corresponding to the length of the paper P to be printed, and T
Stopped at _M1 .

According to FIG. 9B, at T _M0 the photosensitive drum
The charging device 20 is energized at T _C0, which is T ₀₁ seconds after T 12 is rotated, and a predetermined charge is supplied to the photoconductor drum 12 (hereinafter, T _{C0 is referred} to as a charging start time, and is indicated as T _C1) . Charged until the end time of charging). This charging is continued for at least the time corresponding to the length of the paper P to be printed, and T
Stopped at _C1 .

Referring to FIG. 9C, the developing bias voltage of the developing device 22 is activated at T _B0 , which is T ₀₂ seconds after the charging device 20 is activated at T _C0 . This developing bias voltage is applied for at least the time corresponding to the length of the paper P to be printed, and stopped at T _B1 .

The time between T _M0 and T _C0 , ie T _01, is
The time from when the motor is energized until the rotation is stabilized, that is, the rising time lag, is defined by the size of the motor of the printer device 2. Further, the time between T _C0 and T _B0, that is, T _02, is the time during which the position charged via the charging device 20 on the circumference of the photosensitive drum 12 is moved to the developing position of the developing device 22. That is, the development interval, which is defined by the diameter of the photosensitive drum 12 and the rotation speed of the motor.

By the way, generally, the developing bias application start time indicated by T _B0 is from the exposure device 30 to the photosensitive drum.
In order to surely develop the image exposed on 12, the front end region of the photosensitive drum 12, which is charged via the charging device 20 at T _C0, that is, the charging start position is opposed to a developing roller (not shown) of the developing device 22. It is defined prior to the time T _D0 for reaching a certain position, that is, a developing position. The time T ₀₃ between T _D0 and T _B0 is called the tip margin time. Also, the developing bias application end time indicated by T _B1 is similarly set in the charging device.
The time T _C1 at which the charging by 20 ends is defined to be slightly longer than the time T _D1 until it reaches the developing position. This T _B1
The time T ₀₄ between T _D1 and T _D1 is called the trailing margin.

However, it is known that the increase in the leading edge margin time T ₀₃ and the trailing edge margin time T ₀₄ causes a large amount of toner that does not contribute to image formation to adhere to the surface of the photosensitive drum 12. ing. In this case, as shown in FIG. 10, there is a problem that black stripes (due to unnecessary toner) occur before and after the image area to be printed. As is clear from FIG. 10, it is known that this black band is most often formed under the intermittent printing, that is, the printing condition in which the rotation of the photosensitive drum 12 is stopped for each printing. .

When the photoconductor drum 12 is rotated and the charging by the charging device 20 and the application of the developing bias by the developing device 22 are stopped,
It is known that the toner contained in the developing device 22 is randomly attached to the photoconductor drum 12 (generally called fogging). This fogging phenomenon occurs due to the rising time lag T ₀₁ described above and the idle running time T ₀₅ between the time T _B1 when the photosensitive drum 12 is stopped and the time T _M1 when the motor is stopped.

Next, the charging of the photosensitive drum 12 and the developing bias of the developing device 22 are performed to increase the number of prints which can remove the black band and the fog and can be printed with a certain amount of toner. The application will be described in detail.

FIG. 4 shows the timing of charging the photosensitive drum 12 and applying the developing bias to the developing device 22 during the intermittent printing according to the embodiment of the present invention. In FIG. 4, the respective positions T _M0 described in FIG.
T _M1 , T _C0 , T _C1 , T _B0 , T _B1 , T _D0 and T _D1 are shown in FIG.
The same reference numerals are used to omit detailed description. Incidentally, T ₀₁
The period of the between respective positions indicated by the through T ₀₅ is for identification, for displaying the T ₁₁ through T _15.

According to FIGS. 4 (a) to 4 (e), a print start signal (not shown) is input, and at T _M0 the photosensitive drum 12
The static elimination lamp 28 is turned on at T _E0 before the (motor) is rotated. This T _E0 and the T at which the photosensitive drum 12 is rotated
The time T ₁₆ until _M0 is used as a margin time until the brightness of the static elimination light generated from the static elimination lamp 28 becomes stable.

Subsequently, after the time T _{16 has} elapsed, T _M0
Then, the photosensitive drum 12 is rotated, and when the motor reaches the steady speed (0.5 seconds later in the present application), the charging device 20 is energized (T _C0 ). That is, in the present application, the rising time lag T
₁₁ is defined as approximately 0.5 seconds. The charging device 20 is
It continues for at least the length of the paper P to be printed and is stopped at T _C1 .

When the surface of the photosensitive drum 12 charged at T _C0 reaches the developing position of the developing device 22 (T _D0 ), the developing bias is applied (T _B0 , see FIG. 4C). still,
As is clear from FIGS. 4 (b) and 4 (c), in the present invention, T _B0 and T _D0 coincide with each other. Further, the developing bias is a time slightly longer than the time obtained by adding the developing interval T ₁₂ to the charging end T _C1 (0.0 in this embodiment).
2 seconds) and then terminated at T _B1 .

According to FIG. 4D, the charging device 20 is energized at T _C0 , and at the same time, the charge erasing beam is emitted from the exposure device 30 (T _L0 ). This charge erase beam is used in the developing device.
The photosensitive drum 12 immediately before the developing bias is applied from 22
It is used to remove the fog that may occur immediately before the leading edge of the image area by erasing the electric charges on the surface of the image area. The charge erasing beam is stopped before the image is exposed, slightly earlier than the timing T _B0 when the developing bias from the developing device 22 is applied (T _L1 ). Also,
In this case, the developing bias may be applied simultaneously with the charge erasing beam (T _B0 ′ and T ₁₃ ′, see FIG. 4C).
The irradiation of the charge erasing beam (or the simultaneous application of the developing bias) is useful for removing the black band that may occur until the amount of charge supplied from the charging device 20 to the photosensitive drum 12 is stabilized. Is.

FIG. 5 shows a method of defining the timing for stopping the motor (photosensitive drum 12) shown in FIG. 4 (a). As is apparent from FIG. 5, the toner is attracted from the developing roller of the developing device 22 to the region E of the photoconductor drum 12 located immediately below the charging device 20 at the time T _C1 when the charging device 20 is stopped. A sufficient amount of charge is given for this. Therefore, the timing T _M1 at which the motor is stopped is defined as T ₁₇ when the toner attached to the area E is rotated until it is removed via the cleaning device 26 (see FIG. 4B).

FIG. 6 shows a method of defining the timing T _{E1 at} which the static elimination lamp 28 shown in FIG. 4 (e) is stopped. As is apparent from FIG. 6, when the motor (photosensitive drum 12) is stopped at the same time as the charging device 20, the photosensitive drum 12 positioned immediately below the charging device 20 is stopped.
The electric charge is left in the region E of. The electric charge left in the area E is moved by the inertia of the motor and conveyed to the developing roller of the developing device 22. Therefore, as in the example shown in FIG. 5, the toner is attracted to the area E. This may cause a black band to be formed at the leading edge of the image area during the next image formation (printing). Therefore, the static elimination lamp 28 has a predetermined time T after the photosensitive drum 12 is stopped at T _M1 and before the area E passes through the static elimination lamp 28 due to the inertia of the motor.
It is stopped at time T ₁₈ when it has been rotated until ₁₈ has passed. In other words, the time T _E1 at which the static elimination lamp 28 is stopped is defined to be sufficiently longer than the time T _M1 at which the motor is stopped, and the surface of the photosensitive drum 12 rotated to T ₁₇ depends on the inertia of the motor. It is lit up until time T ₁₈ at which the residual potential that may be generated due to the movement can be surely erased (see FIG. 7).
.

FIG. 8 shows the difference in the number of printable sheets obtained by the conventional control method shown in FIG. 9 and the control method of the present invention shown in FIG. still,
In FIG. 4, the description has been made by taking the intermittent single-sheet printing as an example, but the two-sheet printing (the photosensitive drum 12 is rotated at the time when the print start signal is input, and the continuous printing on two sheets of paper is finished, (The state where the rotation of the drum 12 is stopped),
Three-sheet printing (similarly, the photoconductor drum 12 is rotated during continuous printing on three sheets of paper) and ten-sheet printing (similarly, the photoconductor drum 12 during continuous printing on ten sheets of paper). (State of being rotated) is also described.

As is clear from FIG. 8, according to the control method of the present invention, the number of printable sheets is secured approximately 2 to 1.5 times under each printing condition. In particular,
If one sheet is repeatedly printed, the toner collection case of the cleaning device 26 will be increased due to the rapid increase of waste toner.
A situation in which the process unit has to be replaced despite the unused toner remaining on 26b is avoided.

[0075]

As described above, according to the image forming apparatus of the present invention, the charge eliminating lamp is turned on before the photosensitive drum is rotated, and at the same time when the charging device starts charging the photosensitive drum, the developing process is performed. A development bias to the device and an erase beam from the exposure device are provided. Therefore, it is possible to prevent the black toner band from being formed in front of the image forming area. Also, when the image forming beam from the exposure device is finished,
The charging of the layer on the photosensitive drum by the charging device is completed,
The application of the developing bias is stopped when the area of the photoconductor drum, which has been close to the charging device when the charging is completed, passes the developing device, and the area is near the static elimination lamp due to the inertia of the motor. The motor is stopped based on the idle running time that is carried up to, and all image formation is completed.

Therefore, the amount of toner consumed in the non-image area can be reduced, and an image forming apparatus capable of more print output can be provided. Further, since the amount of waste toner that is not used for the image is significantly reduced, there is no need to replace the process unit despite the unused toner remaining. As a result, the number of prints that can be printed with a certain amount of toner is increased, and the print cost per sheet can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a printer device in which an embodiment of the present invention is incorporated.

FIG. 2 is a schematic block diagram showing a printer unit controller incorporated in the printer apparatus shown in FIG.

FIG. 3 is a schematic block diagram showing a control device for controlling the entire printer device shown in FIG.

FIG. 4 is a timing chart showing the timing of applying a charge to the photosensitive drum and a developing bias to the developing device, which is an embodiment of the present invention.

FIG. 5 is a schematic diagram showing a method of defining a timing for stopping a motor.

FIG. 6 is a schematic view showing a method of defining the timing for stopping the static elimination lamp.

FIG. 7 is a schematic diagram in which the timings shown in FIGS. 5 and 6 are superimposed.

FIG. 8 is a graph showing the difference in the number of prints that can be printed by the control method of the present invention and the conventional control method.

FIG. 9 is a timing chart showing the timing of applying the charging to the photosensitive drum and the application of the developing bias to the developing device according to the conventionally used control method.

FIG. 10 is a schematic plan view showing a toner black band which may be caused by the timing shown in FIG.

[Explanation of symbols]

2 ... Printer device, 10 ... Process unit, 12 ... Photosensitive drum, 20 ... Charging device, 22 ... Developing device, 24 ... Transfer device,
26 ... Cleaning device, 28 ... Static eliminator lamp, 30 ... Exposure device, 32 ... Focusing lens, 34 ... Rotating polygon mirror, 36 ... f.theta. Lens, 38 ... Emission mirror, 100 ... Printer body, 102, 122
… Cassette, 104, 124… Take-out roller, 106, 126…
Paper ejection guide, 108, 128 ... Conveying roller pair, 110,
130… Paper transport guide, 150… Aligning roller pair,
152 ... Paper guide before transfer, 154 ... Transfer guide roller, 1
56 ... Manual paper feed guide, 160 ... Fixing device, 162 ... Heating roller, 164 ... Heating heater, 166 ... Pressure roller, 170 ... Discharge roller pair, 172 ... Switching gate, 174 ... Inversion passage, 176
… Second discharge roller pair, 178… First stock tray,
180 ... Second stock tray, 200 ... Process unit controller, 210 ... Process unit control circuit, 212 ... CP
U, 214 ... ROM, 216 ... RAM, 220 ... High voltage generation circuit, 230 ... Electrical component drive circuit, 240 ... Laser exposure control circuit, 260 ... Internal bus line, 300 ... Main control unit, 310 ... Main control circuit, 312 ... CPU, 322 ... ROM, 324 ... RA
M, 326 ... Expansion RAM, 328 ... Non-volatile memory, 332 ... Video RAM, 334 ... Parallel-serial conversion circuit, 340
… Printer interface, 350… Host interface, 370… Bus line.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location G03G 15/04 15/043 15/047 15/06 21/08 9122-2H G03G 21/00 365 9122-2H 342 (72) Inventor Taizo Kawakami 70, Yanagimachi, Saiwai-ku, Kawasaki-shi, Kanagawa Toshiba Intelligent Technology Co., Ltd.

Claims (3)

[Claims] 1. A rotatably formed photoconductor, drive means for rotating the photoconductor, charging means for supplying a predetermined potential onto the photoconductor, and exposure means for irradiating the photoconductor with light. Developing means for developing the latent image formed on the photoreceptor through the exposing means, and a bias having a polarity for reducing the effective value of the potential provided to the photoreceptor from the charging means. Biasing means for supplying an electric potential, discharging means for erasing the electric potential provided to the photoconductor, instructing means for instructing the driving means to start driving, and the photoconductor by the driving means via the instructing means. When the driving of the photoconductor is instructed, the charge eliminating unit is energized prior to the drive of the photoconductor, and the charging unit and the exposure unit are energized when the rotation speed of the photoconductor reaches a predetermined value. ,
When the output of the charging means reaches a predetermined value, the exposure means is stopped, and when the supply of the potential from the charging means is started, the area of the photoconductor which is close to the charging means is developed. The bias means is energized immediately before facing the means, and the exposure means is intensity-modulated according to image information at a timing substantially equal to the timing when the bias voltage is energized via the bias means. The charging means and the exposing means are stopped when the image information supplied to the charging means is stopped, and the area of the photoconductor that is close to the charging means when the supply of the potential from the charging means is ended. The bias means is stopped when the driving means is biased until it opposes the developing means, and the bias means is approached when the potential supply from the charging means ends. A control means for the region of which was the photoreceptor stops the driving means so that the drive means is stopped completely while being opposed to the discharging means at a predetermined timing, the image forming apparatus having. 2. A rotatably formed photoconductor, drive means for rotating the photoconductor, and a photoconductor integrally formed with the photoconductor and detachably attached to the photoconductor. A charging unit that supplies a predetermined potential, an exposure unit that irradiates the photoconductor with light, and a unit that is integrally formed with the photoconductor and the charging unit and that is detachably attached via the exposure unit. Developing means for developing the latent image formed on the photoconductor, and bias means for supplying to the developing means a bias potential of a polarity that reduces the effective value of the potential provided to the photoconductor from the charging means. A charge removing unit that is integrally formed with the photoconductor, the charging unit, and the developing unit and that is detachably attached and that erases the potential provided to the photoconductor; Instructing means to instruct and this finger When the driving of the photoconductor by the driving means is instructed via the means, the charge eliminating means is energized prior to the driving of the photoconductor, and the rotation speed of the photoconductor reaches a predetermined value. Energizing the charging means and the exposure means,
When the output of the charging means reaches a predetermined value, the exposure means is stopped, and when the supply of the potential from the charging means is started, the area of the photoconductor which is close to the charging means is developed. The bias means is energized immediately before facing the means, and the exposure means is intensity-modulated according to image information at a timing substantially equal to the timing when the bias voltage is energized via the bias means. The charging means and the exposing means are stopped when the image information supplied to the charging means is stopped, and the area of the photoconductor that is close to the charging means when the supply of the potential from the charging means is ended. The bias means is stopped when the driving means is biased until it opposes the developing means, and the bias means is approached when the potential supply from the charging means ends. A control means for the region of which was the photoreceptor stops the driving means so that the drive means is stopped completely while being opposed to the discharging means at a predetermined timing, the image forming apparatus having. 3. A photoconductor, driving means for rotating the photoconductor, charging means for supplying a predetermined potential to the photoconductor,
An exposing unit that irradiates the photoconductor charged through the charging unit with light to form a latent image, a developing unit that develops the latent image formed through the exposing unit, and a developing unit. In an image forming apparatus including a bias unit for providing a predetermined bias potential and an erasing unit for erasing the potential provided via the charging unit, T _E0 is a timing at which the charge eliminating unit is energized, and T _E1 is The timing for stopping the charge eliminating means, T _M0 for the timing of _{activating the} driving means, T _M1 for the timing of stopping the driving means, _TL0 for the timing of _{activating the} exposing means, and Y _L1 for the exposure timing of stopping means, tie the timing of the T _C0 is the charging means is energized, the timing of the T _C1 stops the charging means, the T _B0 is the bias means of said developing means is urged Ing, the timing of the T _B1 stops the biasing means, when the surface of the photoreceptor to T _D0 is charged through the charging means reaches the developing position of the developing means, the T _D1 from said charging means When the surface of the photoreceptor, which has been charged, reaches the developing position of the developing means,
Respectively, T ₁₁ is the interval between T _M0 and T _C0 , T ₁₂ is the interval between T _C0 and T _B0 , T ₁₃ is the interval between T _D0 and T _B0, and T ₁₄ is Interval between T _B1 and T _D1 , T ₁₅ between T _B1 and T _M1 , T ₁₆ between T _E0 and T _M0 , T ₁₈ between T _E1 and T _M1 Where T ₁₁ is the minimum stabilization time of the drive means, T ₁₂ is T _D0 , T ₁₃ is 0, T ₁₄ is 0.02 seconds or less, and T ₁₆ is from the static elimination means. The method for controlling the image forming apparatus is characterized in that the time until the luminance of the static elimination light is stabilized is input as parameters, and the above-mentioned T _M1 is set.