JPH06332278A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device capable of automatically correcting the change in image density, etc., caused by the secular deterioration of a photosensitive body. CONSTITUTION:An EEPROM Q4 is attached to a photosensitive body (photosensitive drum). The photosensitive body constitutes an interchangeable unit. The number 50000 of remaining working amount equivalent to the life of the photosensitive body is written in the EEPROM Q4 of the new photosensitive body. When a power source is applied, a microcomputer Q1 writes the remaining working amount of the EEPROM Q4 in a built-in SRAM and counts down one by one every time an image is formed on one sheet. When the power source is turned off, the remaining working amount of the photosensitive body stored in the SRAM is overwritten on the EEPROM Q4. By changing developing bias in accordance with the working amount corresponding to the remaining working amount of the EEPROM Q4, the image density is automatically corrected in accordance with the secular deterioration of the photosensitive body.

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 such as a copying machine or a printer having a photoconductor.

[0002]

2. Description of the Related Art Sensitivity of a photoconductor in an image forming apparatus is deviated due to deterioration over time, and the density of image formation is changed. On the other hand, conventionally, the density is corrected by changing the developing bias and the exposure light amount with an adjustment volume that can be adjusted by the user or a service person (conventional example 1). In addition, the potential of the photoconductor is controlled to correct the shift in the sensitivity of the photoconductor due to deterioration over time (conventional example 2). In addition, a method of storing aged deterioration in a backup memory included in the control unit has been devised (conventional example 3).

[0003]

However, in the conventional example 1,
It is troublesome for the user or service person to adjust the correction value by observing the density change of the image. Further, the potential control of the conventional example 2 is high in cost, and if the photosensitive member is a cylinder and its diameter is small, it cannot be arranged in space. Further, in the conventional example 3, when the unit including the photoconductor is replaced, the contents of the aged deterioration of the backed up memory do not match the units currently mounted at that time, which is a problem.

The present invention has been made to solve such a problem, and an object thereof is to provide an image forming apparatus capable of automatically correcting a change in image density or the like due to aged deterioration of a photosensitive member. is there.

[0005]

In order to achieve the above object, in the present invention, an image forming apparatus is provided with the following (1), (2),
Configure as in (3).

(1) A replaceable unit having a photoconductor and a non-volatile storage means, a means for detecting an operating amount of the photoconductor and storing the same in the non-volatile storage means, and a storage in the non-volatile storage means. An image forming apparatus comprising: a control unit that controls image forming conditions based on contents.

(2) The image forming apparatus according to (1), wherein the image forming condition is a developing bias.

(3) The image forming apparatus according to the above (1), wherein the image forming condition is the amount of light in image exposure of the photosensitive member.

[0009]

With the constructions of (1), (2), and (3), the operating amount of the photoconductor in the unit is stored in the non-volatile storage means in the unit, and the image forming condition is determined based on the stored contents. Controlled. Based on the stored contents,
In the configuration (2), the developing bias is controlled, and in the configuration (3), the light amount of image exposure is controlled.

[0010]

EXAMPLES The present invention will be described in detail below with reference to examples.

(Embodiment 1) FIG. 1 is a sectional configuration diagram for explaining the configuration of an "image forming apparatus" which is Embodiment 1. As shown in FIG.

In the figure, the drive system includes a paper feed unit, a transport unit,
It is separated into a main drive system for driving the photoconductor and the fixing unit and an optical drive system for driving an optical system as a load. An AC synchronous motor 25 is used as a main drive source, and a stepping motor 26 is used as an optical drive source (including a mechanism for reading an image). CONT is a controller unit, which is a microcomputer Q1 and an expansion IC unit Q described later.
A circuit including 2 and the like is provided.

The extension I of the microcomputer Q1
When the excitation drive method is selectively designated by the C section Q2,
It outputs the phase excitation signal applied to each phase A, A *, B, B * of the stepping motor. Further, in the present embodiment, the excitation drive system is switched between the two types of the two-phase excitation system and the two-phase excitation system according to the speed information set in the load.

The paper feeding method is as follows:
Paper feeding from the multi-manual feeding section 24 can be selected. When the paper is fed from the cassette 23, the state is managed by a switch group 31 for detecting the presence / absence of the cassette 23, a switch group 31 for detecting the size of the cassette 23, and a switch 37 for detecting the presence / absence of paper in the cassette 23. Switch 31,
When an abnormality is detected at 37, it is displayed on the display unit described later.

In the case of multi-manual feeding, the state is managed by the switch 32 for detecting the state of the manual feeding portion 24, and when an abnormality is detected, it is displayed on the display portion described later.

The photosensitive member (photosensitive drum) 12 rotates clockwise as viewed in FIG. The photoconductor 12 constitutes a replaceable unit. The photoconductor 12 charged by the primary charger 13 is exposed at a photosensitive position, which will be described in detail later, is developed by the developing unit 15, and is imaged on the transfer paper sent from the paper feeding unit by the transfer unit 14. Is transcribed. The photoconductor 12 after transfer is. The cleaning unit 38 removes the residual toner, and
The process in which the residual potential is removed by the pre-exposure lamp 16 and image formation is performed again is repeated. The transfer sheet on which the image is transferred is mounted on the conveyor belt of the conveyor unit 20 and sent to the fixing unit 21. Fixing unit 2
Reference numeral 1 is composed of three rollers: a drive roller 35, a tension roller 45, and a pressure roller 44. As a heater, a heater 43 in which a resistor is applied on a ceramic substrate
This heater 43 is supported by a heat-resistant plastic supporter 42. Further, a metal stay is attached to the plastic supporter 42 to make it strong.
Further, an endless film 47 is provided on the drive roller 35, the tension roller 45, and the heater 43.

A temperature detecting element (thermistor) 41 is attached to the metal stay, and the temperature detecting element 41 is in direct contact with the back surface of the heater 43. Similarly to the temperature detecting element 41, the other temperature detecting element 48 is attached to the metal stay. Heater 43, plastic supporter 4
2. The heater portion composed of a metal stay and the endless film 47 press the pressing roller 44.

The paper that has passed through the fixing unit 21 is discharged from the fixing unit 21 by the paper discharge roller 22 and is stored on the paper discharge tray 39.

The paper discharge sensor 34 is a sensor for detecting whether or not the transfer paper has normally passed through the fixing unit 21.

FIG. 9 shows an outline view of the ceramic heater. As can be seen from this figure, this heater has a plurality of branches. The branch positions correspond to B4, A4R, B5R, and A5R, respectively, depending on the paper size. When the size is known by the cassette size detection switch group 31, the heater branch is switched according to the size. The switching is performed by the five relay contacts 104, 105, 106 of FIG.
It is performed by 107 and 108.

The drive source of the optical drive system is the stepping motor 26 as described above. As will be described later in detail with reference to FIG. 6, this drive source is configured so that the stepping motor 26 drives a completely different load by operating the drive switching solenoid 27. One load is a unit that constitutes the exposure lamp 4, the first mirror 5, the second mirror 6, and the third mirror 7, and the other load is a unit that constitutes the zoom lens 8. These loads that do not need to be driven synchronously can be driven by a common drive source.

The present apparatus uses a stepping motor 26 of an optical drive unit to control the position of the zoom lens 8 and the multi-step magnification selection function by controlling the speed of the lamp systems 4 to 7, and the original placed on the original glass 3 surface. A function of automatically selecting a density by an optical sensor 40 that detects the reflected light of the sheet, a function of automatically selecting a copying magnification (having communication means) by connecting to an external device (not shown), and an exposure lamp 4 by a stepping motor 26. The page continuous shooting function by controlling the position of the developing unit 15, and further, by forming the plural color images by exchanging the developing unit 15, by providing the switch 36 for detecting the exchange of the developing unit 15, this state is provided. It has a function to switch the control by. Further, as shown in FIG. 11, when the EEPROM / Q3 is connected to the expansion IC / Q2 as a memory backup function, and if an abnormality such as a paper jam occurs, the remaining number of sheets, magnification value, abnormality information, etc. are stored. To do. Further, an EEPROM Q4 is attached to the photoconductor 12 to store the operating amount of the photoconductor (a factor of deterioration over time).
The operating amount of the photoconductor will be described in detail later.

Next, the operation of this apparatus will be described. The power cord (not shown) of this device is connected to a predetermined power source. FIG. 2 shows an operation panel of this device, which is arranged on the upper surface of this device. When one side of the power switch 51 is pressed, power is supplied to the device and at the same time, the power display lamp 52 is lit and displayed.

When the power is turned on, the display on the operation panel is set as the standard mode as follows. Number display 59
Indicates 1, the magnification display 67 displays the same magnification, and A of the automatic density adjustment display 76 lights up.

Further, the display portion of the start key 56 is displayed in red at the time of initial setting when the power is turned on (moving the lens to the same magnification position, etc.) and during copying, and normally copying operation is possible in green display. Is shown.

The controlled temperature of the fixing unit 21 differs depending on the type of the developing unit 15, and the developing unit 1
The type of the developing unit 15 is discriminated by the switch 36 provided at 5, and the set temperature is switched.

Next, the operation of the optical drive system after the power is turned on will be described. The exposure lamp systems 4 to 7 scan and move the document on the document glass 3 from the left end to the right in FIG. 1 to move the document image to the first mirror 5, the second mirror 6, the third mirror 7, the zoom lens 8 and the fourth lens. Mirror 9, fifth mirror 10, sixth mirror 11
Image exposure is performed on the photoconductor 12 via the. That is,
Set the start point of movement to the left end. This position is called a home position (hereinafter referred to as HP). H. H.P. A P sensor 29 is provided. When the power is turned on, the H. When the P sensor 29 does not detect the position of the exposure lamp 4, the control unit by the one-chip microcomputer shown in FIG. 3 controls the stepping motor 26 to rotate the exposure lamp units 4 to 7 to H.264. Move to P side. The start of the rotation control unit will be described with reference to FIG. 6. First, the drive switching solenoid 27 is in the off state (the force of b is not present).
At this time, the switching gear moves in the A direction by the spring pressure. As a result, the output of the stepping motor 26 is connected to the lamp driving gear via the switching gear, and the exposure lamp units 4 to 7 are driven. When the gear for driving the switching gear trump is fitted, the stepping motor 26
Control to lower the rotation speed of.

The exposure lamp units 4 to 7 are H.264. When it is located at P, the stepping motor 26 drives the zoom lens unit 8. As described above, when the power is turned on, the equal magnification value is selected as the standard mode. Further, since the home position (ZHP) of the zoom lens is set to the same size position, the position of the zoom lens 8 when the power is turned on is Z.P. H. It is unknown which side it is with respect to P. Therefore, before the power is turned off, the position of the zoom lens 8 is set to Z. H. It is stored in a non-volatile memory that stores which one is for P.

The operation will be described with reference to FIG. The drive switching solenoid 27 is turned on. As a result, the plunger of the solenoid 27 moves in the b direction. Therefore, the force of b causes the switching gear to move in the B direction against the spring force.
By this movement, the switching gear and the lamp driving gear are disengaged. By further moving in the B direction, the switching gear is fitted with the zoom lens drive gear.
The rotation control when the gears are fitted is the same as described above.

The zoom lens 8 is a Z. H. The lens position is set to Z.P. with the P sensor as a reference position. H. When it is at the position of the P sensor, it is 1 × and the Z. H. The optical system H.P. When it is on the P side, it is an enlargement, and when it is on the contrary, it is a reduction. Expansion rate 2
Position control is performed within the range of 00% to 50% reduction.

At the start of driving the zoom lens, the Z.
H. The operation is understood as follows depending on the state of P.

1) Z. H. When the position of the zoom lens 8 is detected by the P sensor.

A. Once set the zoom lens 8 to the optical system H.264. P. Move to P. H. Stops by putting it in a range that the P sensor does not detect.

B. Move to the right and Z. H. From the time when the P sensor detects it, it moves for a predetermined distance and then stops.

2) Z. H. When the position of the zoom lens 8 is not detected by the P sensor.

A. Depending on the position of the zoom lens 8 stored in the nonvolatile memory, the moving direction of the zoom lens (Z.
H. (P sensor side), and move the zoom lens.

B. When moving to the right, Z. H. From the time when the P sensor detects it, it moves for a predetermined distance and then stops.

C. When moving to the left side, the zoom lens 8 is once moved to the optical system H.264. P. Move to P. H. Stops by putting it in a range that the P sensor does not detect. Move to the right and Z. H. P
It moves for a certain distance from the time when the sensor detects it and then stops.

The above-described operation is the control necessary to prevent the setting position error due to the back crash of the gears.

After that, the drive switching solenoid 27 is turned off. As a result, as described above, the switching gear moves in the direction in which it is fitted with the lamp driving gear. However, in order to fit the zoom lens, it is necessary to rotate the switching gear as described above. At this point, the exposure lamp units 4 to 7 are H.264. It is located on P29.
Therefore, the stepping motor 26 rotates the exposure lamp units 4 to 7 in the direction to move them to the right.

As a result, the exposure lamp units 4 to 7 are H.264. The rotation is stopped at the time when it is disengaged from the P sensor 29 (the fitting of the switching gear and the lamp drive gear is completed), and the rotation is made to rotate in the opposite direction again. After the P sensor 29 is detected, it stops at a predetermined position.

Upon completion of the initial operation of the optical drive system described above, the preparation for the copying operation of this apparatus is completed.

Next, the copying operation by feeding the paper from the cassette 23 will be described.

When the copy start key 56 is pressed, the transfer paper size data by the input signal from the switch group 31 for detecting the cassette size, the number data set by the number key 54, the magnification selection keys 61, 62, 64, 6
The copying operation is started based on the magnification data by 5, 66 and the data by various other mode selecting means.

When the copy start key 56 receives a start instruction, the display of the start key is switched from green to red, and the numeric key 54, magnification keys 61, 62, 64,
Input of mode switching keys such as 65 and 66 is prohibited.
The main drive motor 25 starts rotating, and the paper feed roller 1
8, photoconductor 12, transport unit 20, fixing unit 21
Etc., the driving force is transmitted.

From the start of rotation of the main drive motor 25, 0.
After 5 seconds, a paper feeding solenoid (not shown) is operated, the paper feeding roller 17 is rotated accordingly, and the transfer paper in the cassette 23 is fed toward the paper feeding feed roller 18. The transfer paper feed amount of the paper feed roller 17 is controlled by the cassette size data. That is, when the transfer paper is larger than the predetermined value, the feed amount is increased. When the transfer paper reaches the paper feed roller 18, the transfer paper is sent to the registration roller 19 by the paper feed roller 18, and is stopped when the transfer paper reaches the registration roller 19.
A manual feed switch 33 installed between the paper feed roller 18 and the registration roller 19 detects the transfer state of the transfer paper.

At a predetermined timing until the transfer paper is sent on the paper feed path and reaches the registration roller 19, the exposure lamp units 4 to 7 are permitted to start scanning the original.
At this time, the exposure lamp units 4 to 7 are H.264. P sensor 29
It is in the position detected by. More specifically, during the initial operation or the backward movement of the copy operation,
H. The vehicle is stopped at a position which is moved backward from the position detected by the P sensor by a distance corresponding to the selection magnification at that time.

When the scanning of the original is started, the pulse motor 26, which is the optical system drive source, reaches the drive pulse rate corresponding to the selected magnification value in the direction in which the exposure lamp units 4 to 7 move forward (to the right). Up to, the pulse rate gradually increases (called slow-up control). That is, the moving speed is gradually accelerated to reach the target speed. Although not shown in particular, the pulse motor drive circuit of the present apparatus adopts a constant current control method and has a plurality of drive current values (in the embodiment, 2).
The configuration is such that it can be switched to (stage) (selected by the PB4 output signal of the optical drive pulse motor control signals shown in FIG. 3).

In general, the characteristic of the pulse motor is that the torque decreases as the pulse rate increases. Therefore, a means for switching the constant current set value is provided, and the current value is switched as needed.

In the present apparatus, the set current is lowered during the relatively low pulse rate from the start of movement, and the set current value is controlled to increase when the speed exceeds a predetermined value, and after reaching the target speed. The control for reducing the set current value is performed again after the elapse of a predetermined time. This is mainly for the purpose of preventing noise, temperature rise and out-of-step development of the pulse motor 26.

Next, a method for forming a margin at the leading edge of the image and a method for aligning the leading edge with the transfer sheet will be described with reference to FIG.

As a means for preventing toner adhesion in the non-image area, a charge eliminating means using a light source such as an LED (light emitting diode) lamp or a fuse lamp is generally used. In this apparatus, a grid provided in the primary charging unit 13 is used. 13a
The same effect is realized by controlling the voltage value of. This is an important method in the present situation where it is difficult to arrange a plurality of members around the photoconductor due to downsizing of the apparatus.

The distance e between the exposure point and the grid is Since the distance between the P sensor 29 and the document abutting position cannot be set sufficiently short as compared with the distance b, a predetermined time corresponding to the magnification selection value is set after the start of the movement of the exposure lamp 4 in order to form the front end margin 2 mm of the document. The grid is switched from the L level to a predetermined voltage. That is, when the grid voltage is at the L level, the toner image is not formed because the electric potential is not charged on the photoconductor 12, and the image is formed from the timing when the voltage is switched to the predetermined voltage. Forming a margin.

Next, regarding alignment of the leading edge of the image with the transfer paper, the distance c between the exposure point and the transfer portion is determined by the registration roller 19
And the distance between the transfer paper portion is shorter than the distance d. For this reason, it is necessary to re-feed the transfer paper waiting at the above-mentioned registration roller 19 before the image on the front end of the original is exposed on the photoconductor 12 and feed it toward the transfer section.

In the present apparatus, when the exposure lamp 4 starts moving and reaches the target speed, the exposure lamp 4 is still in the H.S. P
It is detected by the sensor 29. H. The value obtained by dividing the value of distance b + 2 mm by the speed according to the selected magnification from the timing of passing through the P sensor 29 is H.264. It is the time required for the exposure lamp 4 to reach the end portion of the white plate after passing the P sensor 29, and this time is defined as x.

A value obtained by subtracting the time required for the image at the exposure point of the photoconductor 12 to reach the transfer portion from the time from the start of re-feeding by the registration roller 19 to the transfer sheet reaching the transfer portion. Is defined as y, and the time required to feed the transfer paper by 2 mm to this y (2 mm / 100 mm / s = 0.02 sec ...
Transport speed = 100 mm / s) is added. Using the above numerical values, it is calculated by the following formula.

X- (y + 0.02) = Z (sec) From the time when it passes the P sensor 29, the above formula value Z
When the registration roller 19 is operated and the sheet is re-fed at the timing when lapsed, a transfer sheet image with a margin of 2 mm formed according to the selected magnification is obtained.

The exposure lamp units 4 to 7 move a predetermined distance according to the cassette size data, the magnification data, etc., and when the target position is reached, the pulse rate is gradually reduced (referred to as slowdown control), and after stopping, Again H. P sensor 29
Slow-up control and constant speed control in the direction to move backward. And H. At the time when the P sensor 29 is detected, slowdown control for stopping at a position corresponding to the selected magnification is performed and the exposure lamp units 4 to 7 are stopped.

Further, the control of the original scanning distance is also executed by the trailing edge signal of the transfer paper. The control operation described above is shown in FIG.
It is controlled by the one-chip microcomputer shown in. Q1 in FIG. 3 shows a one-chip microcomputer with built-in ROM and RAM. FIG. 8 is a diagram showing the basic configuration of this microcomputer program. The detailed description thereof is omitted.

Next, the control of the exposure lamp 4 will be described. A halogen lamp is used as the exposure lamp 4, and the phase of the AC power supply is controlled so that the lighting voltage of the halogen lamp becomes constant (lamp regulator (not shown)). This lamp / regulator has a lamp lighting voltage V even if the AC input voltage changes or the power supply frequency changes.
It is controlled so that c is constant. Therefore, the trigger signal of the exposure lamp 4 for phase control is output from this lamp regulator and input to the controller. The trigger signal of the exposure lamp 4 is always output regardless of whether or not the lamp is turned on.

Further, the zero-cross signal generated by the zero-cross generation circuit is input to the controller and connected to the microcomputer. Exposure lamp 4 from zero-cross signal
It is possible to read the change in the input voltage by monitoring the time Tc until the trigger signal of.

In this image forming apparatus, the photosensitive member 1 is provided for each device.
The lamp lighting voltage Vc is adjusted so that the illuminance on the two surfaces is constant, and the lamp lighting voltage Vc is stored in the nonvolatile memory. Based on the stored lamp lighting voltage Vc and the time Tc from the zero cross signal to the trigger signal of the exposure lamp 4, the AC input voltage Emax can be obtained from the following equation.

[0063]

[Equation 1]

From these two equations, Erms ² / Vc ² = 1 / {1-2 × Tc / T + SIN (4πTc / T) / 2π} The time Tc from the zero-cross signal to the trigger signal of the exposure lamp 4 By inputting (see FIG. 4), Erms ² / Vc ² can be obtained, and the AC input voltage Erms can be obtained from the lamp lighting voltage Vc stored in the nonvolatile memory.

In the present embodiment, Erms ² / Vc ² is calculated from Tc by the table stored in the ROM.

The control of the heater will be described. This heater is a heater in which a resistor is printed on a ceramic substrate as described above, and has excellent thermal response. Therefore, in the normal on / off control, the ripple becomes large with respect to the temperature control temperature, and the electric power is excessively applied to the heater, and the heater is damaged. Therefore, in this control, power control is performed so that a constant power is applied.
In addition, in order to reduce the ripple, control is performed to switch the power according to the temperature detected by the thermistor.

Here, the power control of the heater will be described. The electric power control of the heater is also performed by the phase control similarly to the control of the exposure lamp 4. Since the heater is purely a resistance load, the electric power W can be obtained by W = V _H ² / R V _H : voltage applied to the heater R: resistance value of the heater.

Since the resistance value R of the heater is stored in the memory at any time as described later and the electric power to be supplied to the heater is known in advance, the voltage V _H applied to the heater is V _H ² = R from the above equation. × W ・ ・ ・ The voltage V _H given to the heater from the formula of effective voltage is

[0069]

[Equation 2]

Erms ² / V _H ² = 1 / {1-2 × T _H / T + SIN (4πT _H / T) / 2π} ... V _H ² is calculated from the formula, Erms ² is calculated from the formula, and E
By calculating rms ² / V _H ² , the time T _H from the zero cross signal to the trigger signal to the heater is calculated from the formula.
(See FIG. 5) can be obtained.

In this embodiment, the table is used for Er
T _H is calculated from ms ² / V _H ² .

Although it has been described that the resistance value of the heater is stored in the memory at any time, a method for storing will be described.
Reference numeral 111 in FIG. 10 is a commercial power supply AC100V, and reference numeral 110 is a triac that is turned on / off according to a trigger signal sig.1 by phase control. When the relay 102 and the relay 103 are turned on, the commercial power source 111, the triac 110, and the heater 43 are connected in series. In this state, the heater is energized. Also at this time relay 1
00 and 101 are off. However, when the voltage is not applied to the heater, the relays 102 and 103 are turned off, the relays 100 and 101 are turned on, and the DC voltage of 5V is divided by the heater and the reference resistor 109. Is supplied to the port of the microcomputer Q1. This port is a port that can detect an analog voltage, and a voltage corresponding to the resistance value of the heater 43 is input. And the microcomputer Q1
Calculates the resistance value of the heater from this voltage and stores the resistance value in the memory. That is, an accurate value is stored regardless of the change in resistance value due to deterioration over time.

However, if the resistance value of the heater is smaller than a predetermined Rmin or larger than Rmax, the microcomputer Q1 determines that the heater is abnormal and does not supply power to the heater. In addition, copying is prohibited for the user.

The electric power of the heater is controlled by the algorithm as described above. This heater power control is always performed during the copy period so that the heater temperature is constant.

Explanation regarding the operation amount of the photoconductor.

As shown in FIG. 11, an EEPROM Q4 is attached to the new photoconductor 12. Further, the contents of the EEPROM Q4 can be read or rewritten by the expansion IC section Q2. At the time of new article, 50,000 sheets corresponding to the life of the photoconductor are written as the remaining operation amount.

On the other hand, the microcomputer Q1 copies the remaining operation amount written in the EEPROM Q4 to the high-speed accessible volatile SRAM built in the microcomputer Q1 among the initials when the power is turned on (FIG. 12). See S2). Further, as shown in FIG. 14, every time one image is formed (S8), the countdown is by one (S9). Since the operation amount of the photoconductor 12 changes depending on the size of the transfer paper, as shown in FIG. 16, if the count number is changed to 2 or 1 depending on whether the size is large or small (S13 to S15). ), The operating amount can be detected more accurately.

Since the EEPROM Q4 has the contents of 16 bits in one address, it is possible to count up to minus 15535 sheets. Further, as shown in FIG. 13, the remaining operation amount of the photoconductor 12 is LN1 (0
When the number of sheets is reached (S6), a display for notifying that it is time to replace the photoconductor 12 is displayed (S7). Further, when the remaining operation amount of the photoconductor 12 reaches a predetermined number LN2 (minus 1000 sheets) (S4), image formation is prohibited (S5). As shown in FIG. 15, the power supply is monitored for down (S10), and when down, the photoconductor 12 stored in the SRAM built in the microcomputer Q1.
Write the remaining operating amount of EEPROM to EEPROM Q4 (S1
1).

As a supplementary explanation of the detection of power source down, there are two systems of 24 V and 5 V as the power source voltage.
Drives loads such as solenoids and motors with 4V, and 5V
Microcomputer Q1, expansion IC section Q2, EEP
Operate ROM / Q4. In addition, there is a difference in that the power supply voltage of the two systems is lowered by turning off the switch when the outlet is pulled out. First, 24V is lowered, and after 1 second or more, 5V is lowered. And the power down detection detects 24V down, and SRAM is detected within 1 second from the detection until 5V down.
The contents of is written in EEPROM Q4.

Explanation regarding density adjustment.

Next, the density adjustment will be described. As a specification, the output density changes depending on the above-described automatic density adjustment or the density level selected by the user. This step is from 1 to 9 steps, and the larger the number, the lighter the density of the output image. The fifth stage is most suitable for standard manuscripts. As a density adjusting method, the developing bias applied between the developing device and the photoconductor 12 is varied and adjusted. Further, since the operating amount of the photoconductor 12 (the factor of deterioration over time) is related to the factor of changing the density, the developing bias is given by the following formula.

Development bias = constant 1 * step + constant 2 * photosensitive member operating amount + constant 3 Since the photosensitive member operating amount is (50000−remaining operating amount), this is substituted into the above equation to develop bias. Is calculated by transforming the formula of development bias into a formula based on the remaining operating amount,
The developing bias may be calculated.

When such a linear expression is not sufficient, a developing bias can be derived by using a table.

In this way, the density can be automatically adjusted according to the operating amount of the photoconductor 12 to always obtain a desired density.

(Embodiment 2) The description is omitted because it is the same as the description except for the density adjustment.

As a specification, the output density changes depending on the above-described automatic density adjustment or the density level selected by the user. This step is from 1 to 9 steps, and the larger the number, the lighter the density of the output document. The fifth stage is most suitable for standard manuscripts. As a density adjusting method, the bias applied between the developing device and the drum is changed and adjusted. The developing bias is determined by the following formula.

Development bias = constant 1 * step + constant When such a linear expression is not sufficient, the development bias can be derived by using a table.

Further, as a factor for changing the density, the photoconductor 1
The operation amount of 2 is also related. Therefore, the correction of the density change due to the operating amount of the photoconductor 12 is performed by changing the lighting voltage of the exposure lamp 4 as shown in the following formula. That is, the amount of light in image exposure is changed to perform the correction.

Lighting voltage = constant 1 * photosensitive member operating amount + constant 3 When such a linear expression is not sufficient, the lighting voltage can be derived in a table.

In this way, the density can be automatically adjusted according to the operating amount of the photoconductor 12 to always obtain the desired density.

Although each of the embodiments described above is an image forming apparatus of a type for copying an original, the present invention is not limited to this and is also applied to an image forming apparatus such as a laser printer which forms an image from an image signal. it can. Further, in each of the embodiments, the operating amount of the photoconductor is counted in the form of "remaining operating amount", but the present invention is not limited to this, and the operating amount may be directly counted.

[0092]

As described above, according to the present invention,
Since the image forming conditions are automatically corrected according to the deterioration of the photoconductor over time, it is not necessary for the user or service person to manually correct the image forming conditions. In particular, if the unit consists of a photoconductor and a developing device, it may be replaced frequently depending on whether you want to use the developing device containing red toner or the developing device containing black toner. There is no need to manually correct
Since the image forming conditions are automatically corrected according to the aged deterioration of the replaced units, it is not necessary to make a trial run. Further, since it does not occupy a space on the surface of the photoconductor as compared with the potential control on the photoconductor, it can be used for a photoconductor drum having a small diameter. Further, the cost is lower than that of the potential control, and the cost advantage is further increased by not only performing the image density correction but also notifying the replacement time of the photoconductor.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross-sectional configuration of a first embodiment.

FIG. 2 is a diagram showing an arrangement of each element on an operation panel.

FIG. 3 is a diagram showing input / output of a one-chip microcomputer Q1.

FIG. 4 is an explanatory diagram of phase control of an exposure lamp.

FIG. 5 is an explanatory diagram of phase control of a ceramic heater.

FIG. 6 is an explanatory diagram of switching the drive target of the stepping motor.

FIG. 7 is an explanatory diagram of margin formation and transfer paper leading edge alignment.

[Figure 8] Basic configuration diagram of the program

[Fig. 9] Outline drawing of ceramic heater

FIG. 10 is a circuit diagram of a ceramic heater drive and resistance value detection circuit.

FIG. 11 is a block diagram of a main part of the first embodiment.

FIG. 12 is a diagram showing initial processing according to the first embodiment.

FIG. 13 is a flowchart showing a process based on the remaining operating amount in the first embodiment.

FIG. 14 is a flowchart showing a countdown of the remaining operating amount in the first embodiment.

FIG. 15 is a flowchart showing the processing when the power supply is down in the first embodiment.

FIG. 16 is a flowchart showing a countdown of the remaining operating amount in the modification of the first embodiment.

Claims (3)

[Claims] 1. A replaceable unit comprising a photoconductor and a non-volatile storage means, means for detecting an operating amount of the photoconductor and storing the same in the non-volatile storage means, and stored contents of the non-volatile storage means. An image forming apparatus comprising: a control unit that controls image forming conditions based on the above. 2. The image forming apparatus according to claim 1, wherein the image forming condition is a developing bias. 3. The image forming apparatus according to claim 1, wherein the image forming condition is a light amount in image exposure of the photoconductor.