JPH03119372A - Image adjustment control system - Google Patents

Abstract

PURPOSE:To speedily perform image adjustment by storing levels including an HV level even if a power source is turned off and starting adjustment at each stored level when the power is again applied. CONSTITUTION:At a time when an image forming device is powered on, or at any appropriate timing, image adjustment is performed, and the surface potential level (HV level) given to a photosensitive belt 41 by an electrifying charger 42, a level (EXP level) of exposure controlling lighting power supplied to flash lamps 21 and 22 from a lamp lighting circuit 212 and the level (TC level) of toner weight ratio T/C are set. After image adjustment, these conditions are stored in a memory. When the image forming device is powered on, the electrophotographic process conditions stored in the memory are set as initial values. Based on the set values, image adjustment is resumed. Thus, the time required for adjustment is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image adjustment control method in an image forming apparatus using an electrophotographic process.

[Conventional technology]

Conventionally, electrophotographic processes have been widely used as a method for forming hard copy images in image forming apparatuses such as copying machines, facsimile machines, and optical printers using laser beams, LED arrays, and the like.

The electrophotographic process consists of a charging process that uniformly charges the surface of a photoconductor, an exposure process that forms a latent image by exposing the surface of the photoconductor according to image information, and a toner process that attaches toner to the latent image. It consists of a developing process to form an image, a transfer process to transfer the toner image to recording paper, and a fixing process to fix the toner image transferred to the paper.

For example, in a copying machine using an electrophotographic process, in order to obtain a hard copy image with an appropriate image density (ID),
Electrophotographic process conditions such as the surface potential of the photoreceptor, exposure amount, and toner i11 degrees are set in advance, and control is performed to maintain the set values (for example,
No. 5-29857).

[Problem to be solved by the invention]

However, with long-term use of a copying machine, impurities adhere to the photoreceptor, the exposure lamp deteriorates, the optical system gets dirty, and the circuit constants of the control circuit change over time.

For this reason, conventional copying machines have had the problem of not being able to obtain appropriate image density after long-term use.

To solve this problem, various state values related to electrophotographic process conditions are detected by appropriate sensors,
It is conceivable to variably adjust the electrophotographic process conditions based on the detected value.

In this case, if the electrophotographic process condition adjustment WI control is started from the reset value every time the copying machine is powered on, the adjustment control will take time, and the startup time of the copying machine will be long. The problem of stroking arises.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide an image forming apparatus that uses an electrophotographic process to obtain a proper image and to shorten the time required for adjustment control as much as possible.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides an image adjustment control method for an image forming apparatus having an electrophotographic process.
In order to obtain a proper image, we perform image adjustments by adjusting the electrophotographic process conditions step by step.
Electrophotographic process conditions after image adjustment are stored in a memory, and when the image forming apparatus is powered on, image adjustment is performed using the electrophotographic process conditions stored in the memory as initial values. shall be.

[For production]

Image adjustment is performed when the power of the image forming apparatus is turned on or at any other appropriate timing.

Image adjustment is performed by stepwise variable adjustment of electrophotographic process conditions to obtain appropriate image density or prevent image fogging.

The electrophotographic process conditions after image adjustment are stored in the memory, and the next time the image forming apparatus is powered on, the electrophotographic process conditions stored in the memory are set as initial values, and the settings are based on the settings. Image adjustment will resume.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front sectional view showing a copying machine A. FIG.

In the figure, copying machine A includes a document feeding section 2, an exposure section 3,
It is composed of an electrophotographic section 4, a paper feed section 6, a paper discharge section 7, and the like.

The document feeding section 2 includes a document tray 11 on which a document is placed, a document feeder 12 that automatically feeds the document, a document glass 13, and the like.

The exposure section 3 includes flash lamps 21, 22, a lens 23, and the like.

The electrophotographic section 4 includes a photoreceptor belt 4 that rotates to the left in the figure.
1, a charging device 42, a developing device 44, a transfer charger 47, a separation charger 48, a cleaning device 50, a main eraser 51, a fixing device 52, and the like.

The paper feed unit 6 includes paper feed trays 61, 62, 63, 64, paper stacks 61a to 64a, and paper stacks 61a to 6 stored in these paper feed trays 61 to 64, respectively.
Conveyance bells) 65, 65, etc., and conveyance rollers 66, 66, etc. that selectively convey any of the sheets stored in paper 4a.
, and a timing roller 67.

The paper discharge section 7 includes a paper discharge tray 71, a sorter 72 having a sorting turbine 73, and a double-sided copy tray 74 in which sheets copied on one side are temporarily stored when performing double-sided copying.
It consists of etc.

The surface of the photoreceptor belt 41 is uniformly charged by passing through the charger 42, and exposed by the exposure section 3 to form a latent image, which is developed by the developer 44 and visualized as a toner image. . In addition, the general operation of each part of the copying machine A is well known, so the details will be omitted.

FIG. 2 is a block diagram schematically showing the control system of the copying machine A.

The control unit 80 controls the entire system of the copying machine A.
PU81. A memory 82 consisting of ROM and RAM and storing various data such as programs and setting levels; an operation display section 83 for operating the copying machine A and displaying various information;
Communication unit 8 that communicates with an external device through a communication line
4. It consists of an interface section 85 that interfaces with input/output devices such as various sensors, high-voltage transformer circuits, and motors. Although not shown, the memory 82 is backed up by a battery.

FIG. 3 is a block diagram showing the arrangement of input/output devices used in copying machine A.

In the figure, a surface electrometer 101 for measuring the surface potential VH of the photoreceptor belt 41 and a sensor for measuring the density of the toner image on the surface of the photoreceptor belt 41 are located close to the surface of the photoreceptor belt 41. AIDC sensors 102 are respectively provided, and a light amount sensor 105 for measuring the light amount of the flash lamps 21 and 22 is provided on the side of the lens 23.
is provided. The light amount sensor 105 is mainly used to detect deterioration of the flash lamps 21 and 22. The developing device 44 also has a toner concentration (
An ATDC sensor (ATDC circuit) 103 is provided to detect the toner weight ratio T/C (wt%) by measuring the magnetic permeability of the developer.

A lamp lighting circuit 212 that can control the light intensity of the flash lamps 21 and 22 in stages, and a charger 42
a high voltage transformer circuit 225 that can control the output of the
A toner replenishment motor 111 is provided for replenishing toner when the toner concentration in the developer tank 112 of the developer 44 decreases.

The interface unit 85 connects each sensor 101 to 103 .
The output signal from 105 is amplified and the A/
D-convert the output signal from the CPU 81 as necessary.
/A Convert.

The developing device 44 uses a developer da made of a mixture of a magnetic carrier and an insulating toner, and uses a well-known magnetic brush method to attach the toner to the latent image passing through the development position.

Inside the developer tank 112, a packet roller 113 for stirring the developer da, a transport magnet roller 114 for transporting the developer da, developing rollers 115 to 117 for attaching toner to the photoreceptor belt 41, and the like are installed. There is.

When the toner concentration falls below the set value, or when it is desired to increase the set value, toner is replenished from a toner tank (not shown) by rotating the toner replenishment motor 111.

The replenished toner is stirred and mixed with the developer da already present inside the developer tank 112 and sent to the bucket and controller 113.
sent to. Frictional charging occurs due to stirring and mixing here,
The magnetic carrier and the toner are charged with opposite polarities. Negative polarity toner is placed on the photoreceptor bell at the development position)4
It adheres to the surface of the photoreceptor belt 41 by electrostatic adsorption with the surface charge of No. 1. Residual charge on the surface of the photoreceptor belt 41 (
In order to prevent toner adhesion (that is, fogging) due to charge remaining after full exposure, the developing rollers 115 to 117
A developing bias VB of a predetermined voltage is applied to.

On the other hand, the paper is conveyed by the timing roller 67 in synchronization with the rotation of the photoreceptor belt 41, and the toner image is transferred onto the paper by the transfer charger 47 at the transfer position. The paper onto which the toner image has been transferred is transferred by a separation charger 48 to a device 52 comprising a photoreceptor bell) 41.
sent to.

Thereafter, the cleaning device 50 removes residual toner from the surface of the photoreceptor bell 41, and the main eraser 51 removes residual charges from the surface to prepare for the next exposure.

FIG. 4 shows that the photoreceptor belt 41 is charged by the charger 42.
FIG. 3 is a diagram showing the set level of the surface potential Vl (applied to the surface potential Vl).

Note that the set level of the charger 42 is referred to as rHV.
The Hv level is set by outputting a control signal (setting data) from the CPU 81 to the high voltage transformer circuit 225.

In FIG. 4, the HV level is level "I nor "5".
If the dark potential (■0) exceeds 650 volts, an overrange occurs. When the range is over, the level is set to "5".

For example, the dark potential ■0 of the photoreceptor belt 41 is 550
To set the HV level to ``3'', set the HV level to ``3'', and use this setting level (level 3) to
A control signal is output from the electrification charger 42 to operate the electrification charger 42. When the flash lamps 21 and 22 are not turned on, the surface potential VH given by the charger 42 is maintained almost unchanged, and the surface potential of the photoreceptor belt 41 becomes the dark potential VO.

The surface potential VH (dark potential ■0) of the photoreceptor belt 41 is measured by the surface electrometer 101, but if the measured dark potential VOr differs from the potential planned by the set HV level, Correction of HV level data is performed. Note that these data are stored in the memory 82.

FIG. 5 is a diagram showing the setting level of the exposure amount applied to the photoreceptor belt 41 by the exposure section 3. As shown in FIG.

The exposure amount is determined by the flash lamp 2 from the lamp lighting circuit 212.
It is set by controlling the lighting power supplied to 1.22. The setting level of exposure amount is called "rEXP level". The exposure amount here is not expressed by the exposure amount itself, but by the bright potential VR of the photoreceptor bell l-41 due to the exposure.

In FIG. 5, for example, in order to set the bright potential VR to 60 volts, the EXP level is set to "4", a control signal is output from the CPU 81 according to this set level (level 4), and the flash lamp 21. 22.

The surface potential VH (bright potential ■R) of the photoreceptor belt 41 is measured by the surface electrometer 101, but if the measured bright potential VRr differs from the potential planned by the set EXP level, Correction of EXP level data is performed. Note that these data are stored in the memory 82 as described above.

The bright potential VR is a potential corresponding to a portion (corresponding to a white background portion of a document) that has been completely neutralized by exposure to light, and even under the best conditions, it does not reach zero volts due to residual charge.

When the bright potential VR is higher than a certain potential RL, a small amount of toner adheres there, causing the background to become dark and dirty, so-called fogging. Therefore, if the bright potential VR is higher than the potential VRL. The HV level or EXP level is set within a possible range so as not to become too high.The potential VRL varies slightly depending on the developing bias VB, but is approximately constant at about 95 volts.

Although not shown in this embodiment, the developing bias VB can also be controlled in stages by setting a set level (VB level).

Further, the value of the toner weight ratio T/C can also be controlled in stages by setting a setting level (TC level).

The TC level is set in increments of 1 when the toner weight ratio T/C is between 5 and 8.

The control for maintaining the toner weight ratio T/C at the set value is as follows:
This is done at any time during the copying operation, but the toner weight ratio T/
The setting value of C is changed in an image adjustment operation described later.

Generally, as the value of the toner weight ratio T/C increases, the developing ability increases. By increasing , it is possible to obtain a hard copy image with an appropriate image density ID. Therefore, in the image adjustment operation described later, when the output of the charger 42 reaches the upper limit at the standard toner weight ratio T/C, the TC level is changed upward. However, if the toner weight ratio TC exceeds 8 [wt%], excessive driving torque will be applied to the packet roller 113, etc., and problems such as toner overflowing from the developer tank 112 will occur, so the toner weight ratio T/C The upper limit of 8[w
t%].

In addition, the H■ level, EXP level, or TC level is
For example, it is reset by a program reset that can be operated by a service person, but unless otherwise, it is stored even if the power is turned off, and adjustment is started from each stored level.

Next, the operation of the copying machine 11A will be explained according to the flowcharts of FIGS. 6 and 7.

FIG. 6 is a main flowchart showing the overall operation of copying machine A.

When the power is turned on, initialization is performed first (step #1).
1) Performs image adjustment (step #12), and then starts a timer T1 to obtain the timing for performing image adjustment (step #13).

Then, it is determined whether the print key on the operation display section 83 has been pressed (step #14). During this time, the timer TI continues to measure time.

If the print key is pressed (YES in step #14), it is determined whether or not the timer T1 has timed up (step #15), and if the timer has timed up, image adjustment is performed (step #16). ). If the time has not expired, image adjustment is not performed and the copying operation is started immediately (step #17).

The copying operation is repeated until a predetermined number of copies are completed (step #1B), and then the timer T1 is reset (step #19), and steps from #13 onward are repeated.

FIG. 6 is a flowchart showing the image adjustment operation.

When performing image adjustment, first save the last data of HV level, EXP level, and TC level to memory 8.
2 and set as their respective levels (step #31).

Photoreceptor belt 41, developer 44, cleaning device 50
, main eraser 51, etc. (step #32
).

The charger 42 is turned on (step #33).

The surface potential VH (dark potential VO) of the photoreceptor belt 41 is measured by the surface potential meter 101 (step #34).

A test toner image (test pattern) is developed on the photoreceptor belt 41 (step #35). This creates a solid black image.

The density of the test pattern is detected by the AIDC sensor 102 (step #36).

Based on the output of the AIDC sensor 102, it is determined whether the density of the toner image is appropriate as desired (step #37).

If it is not appropriate, it is determined whether the HV level is at the maximum level (step #51).

If it is the maximum level, it is determined whether the TC level is the maximum (step #52).

If the TC level is not the maximum level, the TC level is raised (step #57).

Replenish toner and stir developer da in step #
5B), proceed to step #35.

If the HV level is not at the maximum level in step #5I, raise the HV level (step #55),
Proceed to step #33.

Light up the flash lamps 21 and 22 (step #
38).

The amount of charge after exposure of the photoconductor bell) 41, that is, the bright potential V
Measure Rr (step #39).

The measured bright potential VRr is stored in the memory 82 (step #40).

It is determined whether the bright potential VRr is smaller than the potential VRL (step #41).

If YES in step #41, the image adjustment ends.

At this time, no fogging occurs in the image.

If NO in step #41, it is determined whether the EXP level is the maximum level (step #61).

If the EXP level is at the maximum level, the EXP level cannot be raised any further, so a warning is displayed that fogging may occur, and this is notified to the service station etc. by communication (step #62). Finish the adjustment.

If the EXP level is not the maximum level, increase the EXP level (step #63L and proceed to step #38).

In the image adjustment flowchart described above, in order to secure a predetermined image density ID, the HV level is first adjusted, and when the HV level reaches the maximum level and no further adjustment is possible, the TC is then performed. Adjust the bell.

If both the HVC level and the TC level have reached the maximum level, the EXP level is adjusted to prevent capri from occurring.

That is, in order to obtain a predetermined image density of 10, first
The level is adjusted, and the TC level is adjusted only when the HVC level cannot be adjusted completely.This allows a proper image density ID to be obtained, and prevents the TC level from increasing rapidly, causing toner spillage. is prevented.

When performing image adjustment, first save the last data of the HVC level, EXP level, and TC level to the memory 8.
Since the settings are read from 2, adjustments are made more quickly than when starting from each initial value.
The time required for image adjustment becomes shorter. Furthermore, it is possible to prevent control disturbances due to discrepancies between the TC level output to the developing device 44 and the actual toner density state of the developing device 44.

Also, instead of adjusting each level at the same time, you can adjust one level at a time and store each status in the memory 8.
2, the history of the adjustment control becomes clear and maintenance can be performed easily.

In addition, in the overall flowchart of copying machine A, image adjustment is performed once when the power of copying machine A is turned on, and after that, the copying operation is performed after a certain period of time has elapsed after the copying operation is stopped. Since the image adjustment is performed when the copying machine A is about to be printed, even if the copying machine A is left on and off for a long period of time, the image adjustment is performed efficiently and the best image quality can always be obtained.

According to the embodiment described above, it is possible to set the image density ID to a target as appropriate as possible, and to prevent fog from occurring as much as possible.

According to the embodiments described above, each level of HVC level is:
The levels are stored even when the power is turned off, and the next time the power is turned on, adjustment is started from each stored level, so image adjustment can be performed quickly. Additionally, if a certain period of time has passed since no copying operation was performed, image adjustment is performed prior to the next copying operation.
Even if the state of the image changes over time, the image is always adjusted to be appropriate.

In the embodiments described above, the configuration and processing operations of each part of the copying machine A can be modified in various ways other than those described above.

〔Effect of the invention〕

According to the present invention, in an image forming apparatus using an electrophotographic process, an appropriate image can be obtained and the time required for adjustment control can be shortened as much as possible.

[Brief explanation of drawings]

FIG. 1 is a front sectional view showing a copying machine, FIG. 2 is a block diagram showing an outline of the control system of the copying machine, and FIG. 3 is a block diagram showing the arrangement of input/output equipment used in the copying machine. Figure 4 shows the setting level of the surface potential applied to the photoreceptor belt by the charger, Figure 5 shows the setting level of the amount of exposure applied to the photoreceptor belt by the exposure section, and Figure 6 shows the entire copying machine. 7 is a main flowchart showing the operation of FIG. 7, and FIG. 7 is a flowchart showing the operation of image adjustment. A... Copying machine (image forming device), 3... Exposure section, 4
... Electrophotography Department, 41 ... Photoreceptor belt (photoreceptor)
, 42... Charger, 44... Developer, 80
...Control unit, 81...CPU, 82...Memory,
101...Surface electrometer, 102...AIDC sensor, 103...ATDC sensor

Claims (1)

[Claims] (1) In an image adjustment control method for an image forming apparatus having an electrophotographic process, image adjustment is performed by variably adjusting each electrophotographic process condition in stages to obtain a proper image, and the image adjustment method is performed after image adjustment. Image adjustment characterized in that electrophotographic process conditions are stored in a memory, and when the image forming apparatus is powered on, image adjustment is performed using the electrophotographic process conditions stored in the memory as initial values. control method.