JP2854627B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an image forming apparatus used for, for example, a laser printer, an electronic copier, and the like.

(Prior Art) Conventionally, for example, image formation in an image forming apparatus such as a laser printer includes charging, exposure, development, transfer, peeling, cleaning,
It is performed through various steps such as fixing. In such an image forming apparatus, a charging device, an exposure device, a developing device, a transfer device, a peeling device, a cleaning device, and the like are sequentially arranged around a photoconductor, and further, a fixing device for receiving paper from the peeling device is provided, By driving each of the above-described devices in accordance with the rotational movement of the photoconductor, the above-described image forming steps are executed to form an image.

Incidentally, the photoreceptor, the developing device, the fixing device and the like are so-called consumables that are worn by use. Therefore, the replacement time (lifetime) is determined according to the number of uses, and when the number of uses reaches a predetermined value, replacement is required. In order to facilitate such an exchange operation, a plurality of devices among the above devices have been integrated into a unit structure. For example, a photoreceptor, a charging device, an exposure device, a developing device, a transfer device, a peeling device, a cleaning device, and the like are integrally configured as a process unit, and a fixing device and its accessories are integrally configured as a fixing device unit. Have been.
By adopting such a unit structure, adjustment work or the like performed at the time of device replacement is extremely simplified, and maintenance work can be performed efficiently.

Such a consumable unit requires life management, which is performed as follows. First, the life of the unit is set. The life of the unit is such that the number of sheets maintaining the consumables characteristic greatly changes according to the operation status. For example, when an image having a black and white ratio of 6% is continuously copied,
Even if the number of characteristics maintained is about 50,000, the black and white ratio is 1% at 2%.
In the case of copying one sheet at a time, the number of sheets maintaining characteristics may be less than half of 50,000 sheets. Therefore, an appropriate paper passing mode (how to use the image forming apparatus) is set according to the product planning of the image forming apparatus, and the life is set for the paper passing mode. Then, the operation status of the unit is converted into, for example, the number of sheets of paper of a predetermined size and stored in a non-volatile memory provided inside the apparatus, and the content of this memory becomes the above-mentioned predetermined value determined as the life. Is displayed when the unit should be replaced. Such setting of the life of the unit is a very important factor in selling the product. That is, if the life setting is too short, the copy unit price is greatly affected, and if the actual life is shorter than the set life, it appears as a complaint from the customer.

Therefore, conventionally, in order to maintain the consumables characteristics until the set life, a unit having some margin of the set life in the paper passing mode according to the product plan of the image forming apparatus has to be designed. In particular, under strict specifications in terms of image quality, the image quality was designed to be substantially non-existent between the initial stage and the period near the life. With such a design, even if the set life is exceeded, the consumables characteristics do not deteriorate rapidly, and therefore the image quality characteristics do not change. Therefore, it is difficult to determine that the life has expired, and it is used up to about twice the set life. There were many cases.

However, when used beyond such a set life, even if the image characteristics that can be seen are good, contamination inside the apparatus that cannot be seen, deterioration of toner consumption, etc. are gradually progressing. There is no problem, but there is a problem that it occurs as a defect due to use beyond the set life.

(Problems to be Solved by the Invention) In the present invention, as described above, a unit having a margin of a certain percentage of the set life is designed to maintain the consumable property until the set life, so Also, the image quality characteristics do not change, and therefore, it is difficult to determine that the life has expired, so there are many cases where the image is used beyond the set life, and when used beyond such a set life, the image characteristics that can be viewed are good. Even when the unit is not visible, the contamination inside the apparatus, the deterioration of the toner consumption, etc. progress gradually, and this is made to solve the problem that the trouble occurs. It is an object of the present invention to provide an image forming apparatus that can surely determine an image and that can prevent the image forming apparatus from being used beyond a set life.

[Structure of the Invention] (Means for Solving the Problems) An image forming apparatus according to the present invention includes a charging unit configured to charge an image carrier to a predetermined potential, and an exposure unit configured to expose the image carrier charged by the charging unit. Exposing means for forming an electrostatic latent image by developing, an developing means for developing the electrostatic latent image formed on the image carrier by being exposed by the exposing means, and a developing bias voltage applied to the developing means. Voltage applying means for applying, a transfer means for transferring a developer image developed by the developing means to a transfer material, and a fixing means for fixing the developer image transferred by the transfer means on the transfer material. A counting means for accumulatively counting the number of images formed using each of the means, and when the value counted by the counting means reaches a predetermined value, the quality of the image formed by each of the means is reduced. And control means for changing.

(Function) In the present invention, the image carrier is charged to a predetermined potential, the charged image carrier is exposed to form an electrostatic latent image, and the image carrier is formed on the image carrier by exposure. The electrostatic latent image is developed by a developing unit to which a developing bias voltage is applied, the developed developer image is transferred to a transfer material, and the transferred developer image is fixed on the transfer material. The accumulated number is counted, and the quality of the image quality formed when the counted value reaches a predetermined value is changed.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows the appearance of an electrophotographic image forming apparatus (laser printer) using a semiconductor laser, and FIG. 3 shows the internal configuration thereof. This image forming apparatus is connected to a host system (not shown), which is an external device such as an electronic computer or a word processor, via a transmission controller such as an interface circuit. And
When a print start command is received from an external device, an image recording operation is started, and the image is recorded on a sheet as a material to be transferred and output.

This image forming apparatus is configured as follows. That is, in the drawing, reference numeral 1 denotes an apparatus body, and a main control board 2 is disposed at a central portion in the apparatus main body 1 as shown in FIG. An electrophotographic process unit 3 for forming an image is formed behind the main control board 2 (to the right in the state of FIG. 3), and a plurality of function addition control boards 4 are accommodated in a lower front part. A substrate accommodating section 5 is arranged, and a paper discharge section 6 is formed at an upper front portion.

The function addition control board 4 can be mounted up to a maximum of three according to the function to be added (for example, additional types of fonts, kanji, etc.). Further, other functions can be added by inserting the function adding IC cards 17 into three IC card connectors 16 arranged at the front edge of the lowermost function adding control board 4. It has become. Two interface connectors (not shown) are provided on the left end face of the function addition control board 4 at the bottom.
Are provided, and these interface connectors are formed in an opening formed in the left side surface of the apparatus main body 1.
18 (see FIG. 2).

A lower portion of the inside of the apparatus main body 1 is a cassette accommodating section 8 for accommodating the sheet feeding cassette 7.

As shown in FIG. 2, the paper discharge unit 6 is formed of a recess formed on the upper surface of the front part of the apparatus main body 1, and the front edge of the paper discharge unit 6 is folded over the paper discharge unit 6 or as shown in FIG. And a rotatable paper discharge tray 9 that can be deployed to the printer. A notch 9a is formed at the center of the front end of the sheet discharge tray 9, and a rotatable U-shaped auxiliary sheet discharger that can be accommodated in the notch 9a or developed as shown in FIG. A tray 10 is provided, and the size of the paper discharge unit 6 can be adjusted according to the size of the paper P to be discharged. Further, on the upper surface of the left frame portion 1a of the apparatus main body located on the left side of the paper discharge portion 6,
Display LED 11, 7-segment display 1 for 2-digit status display
2, and a control panel 14 on which a switch 13 is disposed, and a manual feed tray 15 is provided on the rear side of the apparatus main body 1.

Next, an electrophotographic process unit 3 that performs an electrophotographic process such as charging, exposure, development, transfer, peeling, cleaning, and fixing will be described with reference to FIGS. 3 and 4. FIG.

A drum-shaped photoreceptor 20 as an image carrier is disposed substantially at the center of the unit accommodating portion. A charger 21, an exposure unit 22a of a laser exposure unit 22 for forming an electrostatic latent image, a magnetic brush type developing device 23 for simultaneously performing a developing process and a cleaning (cleaning) process, a transfer charger 24 including a scorotron, and a brush member Memory removal brush 25 and pre-exposure lamp
26 are sequentially arranged to form the process unit 3. The photoconductor 20 uses an organic photoconductor, and has a configuration in which a charge generation layer and a charge transport layer that covers the charge generation layer are formed on the surface of an aluminum cylinder.

Further, in the apparatus main body 1, the sheet P fed from the sheet cassette 7 via the sheet feeding means 27 and the sheet P manually fed from the manual tray 15 are transferred to the photosensitive body 20 and the transfer charger 24. A paper transport path 29 is formed to lead to a paper discharge unit 6 provided on the upper surface side of the apparatus main body 1 via an image transfer unit 28 therebetween.

On the upstream side of the image transfer section 28 of the paper transport path 29, a transport roller pair 30, an aligning roller pair 31, and a transport roller pair
A fixing device unit 33 and a paper discharge roller unit 34 are disposed downstream. Further, a cooling fan unit 35 is provided above the position where the pair of transport rollers 32 is provided.

Note that an aligning switch 36 is provided near the aligning roller pair 31, and an image transfer unit 28 is provided.
Near the non-image surface side of the paper P
Is provided. The transport guide 37 is grounded and functions to electrostatically float the paper P by suction.

When a print start command is received from an external device 401 (not shown), the photoconductor 20 rotates and is charged by the charger 21. Next, recording data from the external device 401 is input, and a laser beam modulated according to the recording data is generated by the laser
Exposure scanning is performed on the surface 20 to form an electrostatic latent image on the photoconductor 20 corresponding to image information. The electrostatic latent image on the photoconductor 20 is developed by the toner t in the developer magnetic brush D 'of the developing device 23 to be visualized to obtain a toner image.

On the other hand, the paper P taken out of the paper feed cassette 7 or manually supplied from the manual feed tray 15 in synchronization with the toner image forming operation is sent to the image transfer unit 28 via the aligning roller pair 31, and The toner image formed on the sheet 20 is transferred to the sheet P by the operation of the transfer charger 24. Next, the paper P passes through the paper transport path 29 and is sent to the fixing unit 33, where the toner image is fused and fixed to the paper P. Thereafter, the sheet is discharged to the sheet discharge unit 6 via the sheet discharge roller unit 34.

After the transfer of the toner image onto the paper P, the residual toner remaining on the photoconductor 20 is removed by a memory removal brush 25 made of a conductive brush.

Further, as shown in FIG. 4, the fixing device unit 33 includes a heat roller 41 having a built-in heater lamp 40, and a pressure roller 42 pressed against the heat roller 41. The toner image is fused and fixed to the sheet P by passing the sheet P through the sheet P.

The heat roller 41 is in a state in which a cleaner 45 is in contact with the heat roller 41, is in a clean state so as to always perform good fixing, and is controlled by a thermistor 46 to maintain a temperature necessary for fixing. The configuration is made.

In addition, a contact portion between the heat roller 41 and the pressure roller 42
A paper guide 48 is arranged near the upstream side of 47 so that the leading end of the paper P guided to the fixing unit 33 is reliably guided between the heat roller 41 and the pressure roller 42. A paper guide 49 is provided on the paper exit side of the fixing device unit 33, and guides the fixed paper P to the paper discharge roller unit.

The paper discharge roller unit 34 includes a lower roller 50 and an upper roller 51, and a discharging brush 52 that contacts the non-image forming surface side of the paper P is provided in the transport direction.
The upper half including the upper roller 51 and the neutralizing brush 52 is attached to the lower surface of the top cover of the apparatus main body 1 and the transport guide 37, the transfer charger 24, and the like.

In addition, as shown in FIG.
Reference numeral 22 denotes a semiconductor laser oscillator 90, a polygon scanner 93 including a polygon mirror 91 and a mirror motor 92, a first for fθ.
It comprises a lens 94, a second lens 95 for fθ, and reflection mirrors 96 and 97 for guiding the laser beam a to a predetermined position. The control board 101 of the laser exposure unit 22 is connected to the main control board 2 via a connector 102.

Further, the laser exposure unit 22 is housed in a synthetic resin casing 103 having an open bottom surface, and the bottom opening of the casing 103 is closed by a metal shield plate 104, and the upper surface of the casing 103 is closed. Is a state in which the metal shield cover 105 also serving as a reinforcing plate is superimposed. The shield cover 105 has a conductive contact piece 1
When the laser exposure unit 22 is mounted at a predetermined position via mounting means (not shown), the contact piece 106 is in contact with a metal guide rail that guides the developing device 23 slidably. And the charger 21
This prevents erroneous operation due to electrostatic adverse effects from inside or the like.

In order to simplify the electrophotographic process, the developing device 23 employs a reversal developing method and a method of removing the transfer residual toner t simultaneously with the development. The developing device 23 includes a casing 121 having a developer accommodating section 120 as shown in FIG. Contains a two-component developer D composed of a toner (colored powder) t and a carrier (magnetic powder) c.
Further, a portion of the developer magnetic brush D 'formed on the surface of the developing roller 122 in sliding contact with the photoconductor 20, that is, a developing position
A doctor 124 that regulates the thickness of the developer magnetic brush D ′ is provided upstream of the photoconductor 20 in the rotation direction of the photoconductor 20. Further, the developer accommodating section 120 has
Second developer stirring bodies 125 and 126 are accommodated therein. In addition,
The developing device 23 is provided with a toner cartridge (not shown) as a toner replenishing device so that toner t is supplied to the developer accommodating portion 120 as appropriate.

The developing roller 122 includes a magnetic roll 130 having three magnetic pole portions 127, 128, and 129, and a non-magnetic sleeve 131 that is fitted around the magnetic roll 130 and rotates clockwise in the drawing. Three magnetic pole portions 127, 128, 1 of the magnetic roll 130
Of the 29, the magnetic pole portion 128 facing the developing position 123 is an N pole, and the other magnetic pole portions 127 and 129 are S poles. The angle theta ₁ between the magnetic pole portion 127 and the magnetic pole portion 128 150 °, the magnetic pole portion 1
Angle theta ₂ between the 28 and the magnetic pole portion 129 is 120 ° set. Then, the electrostatic scraping force of the magnetic brush development using the two-component developer D, the electrostatic potential on the reversal development, and the potential difference between the developing bias applied to the magnetic brush D ′ and the electrostatic potential on the photoconductor 20 cause The residual toner t is mechanically and electrically collected simultaneously with the development of the latent image.

Further, the developing device 23 integrally incorporates the photoconductor 20, the charging charger 21, the memory removing brush 25, and the like to constitute a process cartridge 85. The process cartridge 85 can be inserted into and removed from the apparatus main body 1. It has become. Further, a cleaning brush 144 for cleaning the lower roller 31a of the aligning roller pair 31 is mounted on the upper surface side of the process cartridge 85.

Next, a control system of the image forming apparatus will be described with reference to a block diagram shown in FIG. In the figure, reference numeral 401 denotes an external device such as an electronic computer, a word processor, an image processing device, etc., which is connected to the device by the interface connector. This external device 401 is electrically connected to a control circuit 402 of the present device by a video interface.

The control circuit 402 includes a microcomputer (not shown) (hereinafter, referred to as “CPU”), a RAM 402a, and an erasable
ROM A402b, a PROM, R, an electrically erasable PROM
OM B402c and the like, and the CPU performs various data processing and various controls. The RAM 402a temporarily stores image data to be processed by the CPU, or stores various data necessary for the operation of the CPU. ROM A402
b mainly stores a program for operating the CPU. The ROM B402c stores the accumulated value of the number of printed sheets and the like by using the characteristic that the contents are not erased even when the power is cut off and are electrically rewritable (for details, see FIG. See below).

The cooling fan unit 35, various solenoids 404, a main motor 405, and various switches 406 are connected to the control circuit 402 via a driver circuit 403. Further, in addition to the control of the laser exposure unit 22 and the control panel 14 described above, a high-voltage power supply 407 is controlled, or a signal from the cassette size switch 408 is input. Further, by turning on the main switch 410, 100V AC power is supplied to the AC power supply 411, and the DC power supply 412 generates necessary DC power, which is supplied to the control circuit 402 and other circuits. It has become. The output of the AC power supply 411 is supplied to the fixing unit 33.

Listing the main functions of the control circuit 402,
It is as follows. (1) Decoding the information from the video interface, that is, the command from the external device 401,
Each part of the device is controlled according to the instruction. Also, the status corresponding to the command is output to the external device 401 via the video interface. (2) The display contents are output to the LED 11 and the 7-segment display 12 of the control panel 14. (3) On / off control of various solenoids 404 is performed. (4) The information from the various switches 406 is fetched and processed. (5) On / off control of the mirror motor 92, power setting of laser emission, and power monitoring are performed. (6) Process the toner density information from the toner density sensor. (7) Control the high voltage power supply 407. That is, output on / off control and output power setting for the charging charger 21, output on / off control and output power setting for the transfer charger 24, developing bias on / off control and output power setting, and memory removal brush 25 on / Off control and output power setting.
It also monitors whether each output is operating normally.
(8) On / off control of the main motor 405 and monitoring of whether or not steady rotation is performed. (9) On / off control of the fan motor of the cooling fan unit 35 is performed. (Ten)
On / off control of the pre-exposure lamp 26 is performed. (11) The temperature of the heat roller 41 of the fixing unit 33 is monitored, and the on / off control of the heater lamp 40 is performed.

As described briefly above, the control circuit 402
Is equivalent to a command unit of the main unit 1 and performs various controls.

Next, the operation of the above configuration will be described with reference to the flowchart of FIG.

First, the main switch 410 of the image forming apparatus is turned on and A
When power is supplied to C power supply 411, + 5V of DC power supply 412
Stand up. At this time, a reset signal is generated by a reset signal generation circuit (not shown) and the control circuit 40
2 CPU is reset. Next, the CPU performs an initialization operation. That is, the RAM 402a,
Data such as an input / output port (not shown) and an interface between external devices is initialized (step S1). Next, an error check accompanying the initialization is performed (step S2). This error check is for checking whether or not an error factor has occurred in the initialization operation. If an error occurs during initialization, error processing is performed, and a predetermined code corresponding to the cause of the error is displayed on, for example, the 7-segment display 12 on the control panel 14.

When the above error check is completed, the fixing unit 33
Is started (step S3), and the warm-up operation starts. The temperature control of the fixing unit 33 is performed by a subroutine (not shown) called every 30 msec in a main routine (not shown). Note that the temperature control of the fixing unit 33 is continued not only during warm-up but also during standby and printing.

When the warm-up operation starts, the mirror motor
92, rotate the main motor 405 (steps S4 and S5), check the mirror motor rotation, check the main motor rotation,
Various checks such as a laser emission check are performed (step S6). During the warm-up, the pre-exposure lamp 26 and the charging charger 2 are used to initialize the process control.
1. The memory removal brush 25 and the developing bias are sequentially turned on / off. At this time, the mounting check of the transfer charger 24 is also performed by turning on the transfer output to the transfer charger 24 for a short time while checking the mounting of the charging charger 21 (steps S6 and S7).

In this state, if the temperature of the fixing unit 33 reaches the specified temperature and the end of the warm-up is determined without any error (Step S7), the main body device 1 enters the ready state, The mirror motor 92 and the main motor 405 are stopped (Step S8). Next, a print request signal is output as the status of the main device 1 (step S9). Then, the main unit 1 enters a state of waiting for a print command to be issued while performing an error check (steps S10 to S11). In such a state,
When the external device 401 transmits a print command and the main device 1 receives the print command, the printing operation is started.

That is, when it is determined that the print command has been received (step S11), first, it is checked whether or not the print unit 3 or the fixing unit 33 has passed the replacement time (step S12). The replacement time is determined by referring to a counter (details described later) provided in the ROM B402c. Then, when it is determined that the replacement time has passed, image quality reduction processing is performed (step S13). In the subsequent transfer operation, the transfer of the toner image formed on the photoconductor 20 to the sheet P is performed in a state where the image quality is deteriorated.

Here, the image quality reduction processing will be described. First, the processing when the life of the photosensitive drum 20 has expired will be described.
When the life of the photoconductor drum 20 comes to an end, the residual potential Vr of the photoconductor generally increases, and the ground fog increases,
Phenomena such as white streaks and black streaks appearing in the image due to an increase in 20 scratches occur. Such a state is referred to as a developing bias potential.
A process of artificially creating a process condition change of V _B and charging potential V _O is performed.

FIG. 6 shows the developing bias potential V _B and the charging potential V _O when the residual potential Vr is artificially raised to cause ground fogging.
FIG. To the set lifetime regular cleaning potential is regarded that there is no residual potential Vr 'V _B -V _W "is the condition is sufficient. Control circuit 402 is ROM B402c
When it is determined that the life of the photosensitive member has expired by referring to the counter provided in the printer, as shown in FIG.
A developing bias V _B to lower. Although actually less contributes to the amount of the head when the residual potential Vr is greater potential "V _B -Vr" is realized by this to lower the developing bias conductive zone V _B. In this case, when only the lower developing bias potential V _B, the developing potential "V _O -V _B" increases, as shown in FIG. 6 (b), the charge potential V _O also developing bias potential V _B
As well as the change in This developing bias potential V _B ,
By increasing the change in the charging potential V _{O as} the number of sheets passing over the set life is increased, an image having the same image quality as the life of the photoconductor is approached can be obtained.

The scratch on the photosensitive drum 20 is realized by the following method. Figure 7 shows the timing of the developing bias voltage V _B is applied. This shows how to apply the developing bias near the set life + 10% in the above example. In the image portion, which reduces the development bias potential V _B in order to generate a background fogging. In the non-image portion between the image portion and the image portion, the control circuit 402, it is determined that the photoreceptor life came by reference to the counter provided in the ROM B402c, than the normal developing bias potential V _B The carrier c is caused to adhere to the photosensitive drum 20 in the non-image area by setting the height to be higher. Then, the photosensitive drum 20 is rotated with the carrier c attached thereto, and the carrier c is sandwiched between the memory removing brushes 25. As a result, the carrier c has a sufficiently high hardness, so that the photosensitive drum 20 is forcibly damaged. Due to this scratch, white streaks and black streaks appear on the image, and it is possible to inform the user that the drum life has expired.

Next, a process for creating a state where the life of the developer has expired will be described. As a simple example of the life of the developer, when the image density ID decreases, a problem such as occurrence of background fog occurs. 8 is a diagram showing in performing state life came in the developer in the process conditions change, the developing bias potential V _B, a change in the charging potential V _O. This is a method similar to the method shown in FIG. 6, except that the potential “V _O
−V _B ”is gradually reduced, and the potential“ V _B −Vr ”that contributes to the amount of fog is gradually reduced. That is, when lowering the developing bias potential V _B for example 50 V,
Charging potential V _O is not 50V Similarly, larger value, the image density ID reducing generated by a method of lowering example 200V.

In addition to the above, after the set life has elapsed, the image density ID can be reduced by changing the reference value of the automatic toner control to make the toner density lower than the established value.

When the image quality lowering process is completed, the control temperature of the fixing unit 33 is increased (step S14). This is because the temperature of the fixing unit 33 is set lower in the standby state than during the fixing operation, so that the heater lamp 40 is forcibly turned on so that the fixing temperature is quickly reached at the same time as the start of the printing operation. And set the control temperature higher. Next, the mirror motor 92 and the main motor 405 are rotated (step S
15, S16). Further, a feed solenoid (not shown) is turned on for a predetermined time (step S18). When the feed solenoid is turned on for a predetermined time, a half-moon feed roller is turned on.
27 rotates once, and the paper P is taken out of the paper feed cassette 7 and transported to the transport roller pair 32. In the case of paper feeding from the paper feed cassette 7, the transport roller pair 32 is always rotating,
The sheet is conveyed to the aligning roller 31 via the aligning switch. At this time, the CPU sets the aligning switch 36 to the paper P within a specified time after operating the paper feed solenoid.
Is detected, and if the paper P is not detected, it is processed as a paper feed unit jam (step
S18).

By the way, when the paper P reaches the position of the aligning roller 31, the aligning roller 31 is stopped, and the transport roller 32 tries to transport the paper P further. However, when the leading end of the sheet P comes into contact with the aligning roller 31, the conveyance roller 32 slips, and the sheet P is controlled so as not to bend. On the other hand, in parallel with the conveyance of the sheet P, an image data transfer request is transmitted from the main device 1 to the external device 401 (step S19). Thereafter, when a synchronization command notifying the start of the transfer of the image data is received within a predetermined time (step S20), the transfer of the image data is started (step S2).
1), an unillustrated aligning solenoid is turned on (step S22). As a result, the aligning roller 31 rotates, and the paper P is transported to the photosensitive drum 20. On the other hand, if no synchronization command is received within the predetermined time, it is processed as a synchronization error.

When receiving the synchronization command, main device 1 transmits an image clock. Since the external device 401 transfers the image data in synchronization with the clock, the main device 1 receives the image data. This image data is sent to the laser unit driver 22a of the laser exposure unit 22 via the control circuit 402, and further the semiconductor laser oscillator 90
Supplied to Thereby, laser exposure is started. That is, the laser unit driver 22a modulates the laser light by driving the semiconductor laser oscillator 90 according to the signal level of the image data. The modulated laser light is converted into a parallel light flux by a collimator lens (not shown) and is incident on a polygon mirror 91. The polygon mirror 91 is directly driven by a mirror motor 92 and rotates at a constant speed. The laser light reflected by the polygon mirror 91 is converted into a first lens 94 for fθ, reflection mirrors 96 and 97,
The light is condensed on the photoconductor 20 via the second lens 95 for fθ,
The light spot scans the photoconductor 20 at a constant speed.

In parallel with the scanning, the conveyance of the paper P and the rotation of the photosensitive drum 20 are continued. That is, the pre-exposure lamp 26 is turned on and the charge is removed from the photoconductor 20, and then the charger 21 is turned on and the surface of the photoconductor 20 is uniformly charged. Charging is performed by corona discharging the output of the high voltage power supply 407 with a scorotron charger, and is charged to a negative potential.

By scanning and exposing the negatively charged photoconductor drum 20 with laser light, an electrostatic latent image corresponding to the image data is formed on the photoconductor drum 20. This electrostatic latent image is developed by the toner t in the magnetic brush D 'of the developing device 23,
It is visualized.

On the other hand, the sheet P conveyed to the image transfer section 28 of the photosensitive drum 20 is transferred to the sheet P by turning on the transfer charger 24 by turning on the transfer charger 24. . Next, the paper P passes through the paper transport path 29 and is sent in by the fixing unit 33. The fixing device unit 33 includes a heater roller housing a heater lamp 40.
41, and a pressure roller 42 pressed by the heater roller 41, and the toner image is fused and fixed by the paper P passing between the rollers 41 and 42. Then, the paper reaches a paper discharge roller unit 34 via a paper discharge switch (not shown), and is discharged to the paper discharge unit 6. Also in this case, the CPU sets the paper ejection switch to the sheet P at a specified time after operating the aligning roller 31.
Is monitored (step S23). If the paper discharge switch does not detect the paper P at this time, the paper is processed as a paper discharge section jam. After the toner image is transferred onto the paper P, the toner remaining on the photosensitive drum 20 is removed by a memory removing brush 25 made of a conductive brush, the memory is removed, and the toner is collected in the next developing step. become.

Also, an error check is performed during the printing operation, that is, until the transfer of the image data is completed. When an error occurs, an error process is performed (steps S24 and S25). on the other hand,
When the transfer of the image data is completed without any error, an image data transfer end process is performed (step S26).

Next, the aligning solenoid is turned off, and the aligning roller 31 is stopped (step S27). Then, it is determined whether or not the paper discharge switch detects the paper P at a specified time after the operation of the aligning roller 31 is stopped (step S28). At this time, if the paper discharge switch is kept on, that is, if the paper P is not detected, the paper is processed as a paper discharge unit jam. On the other hand, the paper discharge switch is turned off,
Is detected, the mirror motor 92 and the main motor 405 are stopped (step S29), and the control temperature of the fixing unit 33 is lowered (step S30). This makes the fuser unit 3
3 returns to the original standby state and ends printing of one sheet. To continue printing, the process returns to step S10, and the same operation is repeated.

When a paper jam occurs, the operator releases the cover, removes the jammed paper P, and then closes the cover to clear the error state. Then, when the error state is released, the process returns to step S2, and the same processing as described above is performed.

In the present image forming apparatus, the number of printed sheets P is counted in a nonvolatile memory in order to manage the use state. At this time, the A4 size horizontal feed (210 mm) is set to "1" as a counting reference, and each sheet P is converted to 210 mm for counting. For example, in the case of A3 size, since the length in the transport direction is 420 mm, the converted value is “2”.

In this embodiment, a ROM B402c composed of an electrically erasable PROM is adopted as the above-mentioned counter of the number of printed sheets.

FIG. 9 shows the allocation of the ROM B402c. The counting of the paper P is performed by converting the time during which the aligning roller 31 is rotating in the RAM 402a. When the time is rotated by A4 horizontal size, the counting area TOTALC in the ROM B402c is set to “+1”, and T
Every time OTALC is set to “+50”, PRCSC0 / PRCSC1, DVC0 / DVC
1. Each area of FXC0 / FXC1 is incremented by “+1”. In other words, TOTA
LC stores the total number of printed sheets in A4 horizontal size conversion, and this value converted to a 50-digit number is used as the total count, process unit life count, and fuser life count.
These are stored in the PRCSO0 / PRCSC1, DVC0 / DVC1, and FXC0 / FXC1 areas, respectively. According to such a counting method, when the process unit 3 or the fixing unit 33 reaches a predetermined value, the CP
Each U determines a life end (life), displays the effect, and indicates the life end on the interface status. When the new process unit 3 is mounted and normalization of the toner sensor is completed, the DVC0 / DVC1 area is cleared to "0", and printing becomes possible again, and the count of the process unit 3 starts from "0". Also,
FXC0 / FXC1 is cleared to “0” when replaced with a new fuser unit 33. Also, each area of ROM B402c is 100
Although data rewriting is guaranteed only up to 00 times, the life of each unit is as large as 300,000 or 500,000, so when TOTALC counts up to 10,000, the next address changes from "0" to "+1". Thereafter, the address is sequentially updated every 10,000 counts. That is, one storage area is discarded every 10,000 counts. Therefore, it is necessary to manage the current address. Therefore, the current address is held in BANK00 / BANK01 and used as an address pointer. Also, if a non-writable area occurs on the way, the counting area is moved to the area indicated by the next address. However, since the calculation of the total count to be performed later is performed with reference to the contents of BANK00 / BANK01, if no measures are taken, the count increases by a maximum of 1000 each time a defective area occurs. Therefore, the number of these defective areas is calculated as BANK10 / BANK11.
To be used for correction of the total count calculation performed later.

However, in the above-described method, in the case of one-sheet printing immediately after the power is turned on, TOTALC is not incremented by 1 when the size of the sheet P is smaller than the A4 horizontal size, for example, the size of the B5 size sheet P. Therefore, when printing the first sheet immediately after turning on the power,
Even when the paper P is smaller than the A4 horizontal size, “+1” is always set when the paper P passes. If the power-on state is continued at this time, the size of the second and subsequent sheets P is counted by the RAM 402a, so that the count error can be corrected.

The ROM B302c is used as the above-described counting area, and stores a top / left margin, an initial value of the toner sensor, and the like.

Although the case of cassette paper feeding from the paper cassette 7 has been described above, the case of manual paper feeding is basically the same. Printing by manual paper feed is started when the main device 1 receives a manual paper feed command from the external device 401. When a manual feed command is received, the main unit 1 operates a manual feed tray with a manual switch (not shown).
It is detected whether or not the paper P is inserted in the reference numeral 15. Paper P
Is not detected, the fact is displayed on the control panel 14 to notify the operator that there is no manual paper.
When the paper P is inserted into the manual paper feed tray 15 and the paper P is detected by the manual feed switch, the mirror motor 92 and the main motor 405 are rotated, the paper is transported by the transport roller 32 to the aligning roller 31, and the external device is Wait for a print command from 401. If the sheet P is pulled out by the operator before accepting the print command, it is displayed that the sheet P cannot be detected again. When the print command and the synchronization command are received from the external device 401 in a state where the paper P has reached the aligning roller 31 and the image data transfer is started, the aligning solenoid is turned on, and the aligning roller 31 is rotated to rotate the paper P. The sheet is conveyed to the photosensitive drum 20. Thereafter, the printing process, the detection of a jam, and the like are the same operations as the sheet feeding from the sheet feeding cassette 7 shown in FIG. However, for the paper size, a command for each paper size is received from the external device 401, and control such as counting of the number of prints is performed based on this data.

As described above, in the above-described embodiment, the number of times of printing is accumulated and counted in the ROM B402c, which is a nonvolatile memory, and when the counted value reaches a predetermined value, for example, the process condition is changed. The Uno control, which lowers the image quality by changing the image quality, makes it possible to determine that the unit has reached the set service life, and to prevent the unit from being used beyond the set service life. It can be done.

In the above embodiment, the case where the present invention is applied to laser printing has been described. However, the present invention can be applied to an apparatus employing an electrophotographic process system such as an electronic copying machine, and has the same effect as the above embodiment.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide an image forming apparatus that can reliably determine that a unit has reached a set life and that can prevent use of the unit beyond the set life. .

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a block diagram showing an overall configuration of a control system, FIG. 2 is an external perspective view of an image forming apparatus, FIG. FIG. 4 is a partial vertical sectional side view, FIG. 5 is a flowchart for explaining the operation, FIG. 6 is a diagram showing changes in the developing bias potential and the charging potential when the residual potential is increased in a pseudo manner. FIG. 7 is a diagram showing the application timing of the developing bias when the photosensitive drum is damaged, FIG. 8 is a diagram showing a change in the developing bias potential and the charging potential when creating a state where the life of the developer is over, and FIG. The figure is a diagram for explaining area allocation of ROM B. 20 photoconductor 21 charging charger (charging means) 22
…… Laser exposure unit (exposure means), 23 …… Developing device (developing means), 24 …… Transfer charger (transfer means), 33
... Fixing unit (fixing means), 90 Semiconductor laser oscillator, 402 Control circuit (control means), 402c
... ROM B (counting means), P ... paper (transfer material).

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 15/00 303 G03G 21/00 370-540 B41J 29/20 B41J 29/42 B41J 29/46

Claims (1)

(57) [Claims] A charging unit configured to charge the image carrier to a predetermined potential; an exposure unit configured to expose the image carrier charged by the charging unit to form an electrostatic latent image; Developing means for developing an electrostatic latent image formed on the image carrier by being exposed to light, voltage applying means for applying a developing bias voltage to the developing means, and a developer developed by the developing means Transfer means for transferring an image to a transfer material; fixing means for fixing the developer image transferred by the transfer means onto the transfer material; and cumulatively counting the number of images formed using the respective means. Counting means, when the value counted by the counting means reaches a predetermined value,
An image forming apparatus comprising: a control unit that changes a quality of an image formed by each of the units.