JPH0635323A - Toner density control method - Google Patents

Abstract

PURPOSE:To carry out variation control of the toner density in an image forming device utilizing a two component developing method and to output at a specified image density from the start of printing after the variation without varying the complicated processing factors. CONSTITUTION:In the image forming device provided with a toner replenishing means 28 replenishing toner to a developing device, a toner density detection means 25 detecting the toner density and a control part 31 controlling the toner replenishing means 28 by comparing the toner density detection output and the set toner density, a toner density specification means 30 specifying the toner density of the developing device 2 is provided, a state where the image formation cannot be carried out is set according to the specification of the variation of the toner density and the state where the image formation can be carried out is made after the toner density variation process is completed by varying the set toner density to a specified density and carrying out the toner density varying process so that the detected output by the toner density detection means 25 is made to be the specified density by the toner density specification means 30.

Description

Detailed Description of the Invention

(Table of Contents) Industrial Application Field of the Prior Art Problems to be Solved by the Invention Means for Solving the Problems (FIG. 1) Action Example (a) Description of One Example (FIGS. 2 to 8) (b) Description of other embodiments Effects of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner density control method for controlling the change of toner density in an image forming apparatus using a two-component developing system.

In an image forming apparatus such as a copying machine, a printer or a facsimile machine, an electrophotographic system is widely used because a high speed and high quality output can be obtained. In such an image forming apparatus, an electrostatic latent image is formed on an image bearing member such as a photosensitive drum, a developing device develops it with a developer, and the image is transferred onto a sheet. , Can be controlled by the electrostatic latent image intensity.

With the recent diversification of print output, for example,
Depending on the application of the computer, the print output may be the output of only characters, the output of graphics, the output in which both are mixed, etc. The required image density differs depending on the type of these print outputs, and the contents to be expressed. , The required image density varies depending on the image elements included and the user's preference.

For example, in a document including ruled lines, it is preferable that the image density is lower than that in a document not including ruled lines. For this reason, it is necessary to instruct the switching of the print image density from the higher-level device (computer) or the operation panel, and the printing apparatus to perform printing with the image density specified by the switching.

[0006]

2. Description of the Related Art In a two-component developing type electrophotographic apparatus, a toner density in a developing device or a developed image density is detected, and when the density falls below a predetermined value (slice density), a developer is developed. The toner is supplied (supplemented) to the toner and is controlled to maintain a predetermined toner concentration.

Conventionally, by changing the slice density for providing toner density control in accordance with a print density designation instruction,
It has been practiced to change the print image density by changing the toner density in the developing device.

Another method is to change the combination of the electrophotographic process control elements such as the charge amount (surface potential) of the photosensitive drum, the developing bias voltage, and the transfer current.

[0009]

However, the prior art has the following problems. In the former conventional technique, only the slice value for control is changed, and the actual toner density is consumed / supplemented and changed while printing, so the print output immediately after the image density is changed and designated. Does not reach the specified image density, and in the case of a small amount of output, the specified image density may not be achieved over the entire output.

In the latter prior art, in order to maintain a good print output, the control element is controlled by taking into consideration the environment inside the apparatus (temperature and humidity) and the characteristics of the developer and toner (temperature and humidity characteristics, charging characteristics). It is necessary to determine the optimum value, control becomes complicated, and it is difficult to determine the optimum value.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a toner density control method capable of outputting a designated image density from the start of printing after a change without changing a complicated process element.

[0012]

FIG. 1 shows the principle of the present invention. According to claim 1 of the present invention, the image carrier 10, latent image forming means 11 and 12 for forming an electrostatic latent image on the image carrier 10,
Developing device 2 for developing the electrostatic latent image on the image carrier 10 with a developer
And a toner replenishing means 2 for replenishing the developing device 2 with toner.
6, 28, a toner density detecting means 25 for detecting the toner density of the developing device 2, and a detection output of the toner density detecting means 25 and a set toner density are compared to control the toner replenishing means 26, 28. In the image forming apparatus having the control unit 31 for controlling the toner concentration, a toner concentration designating unit 30 for designating the toner concentration of the developing device 2 is provided, and the control unit 31 designates the change of the toner concentration by the toner concentration designating unit 30. In accordance with the fact that the image forming is not possible,
The set toner density is changed to a specified density, a toner density changing process is performed so that the detection output of the toner density detecting means 25 becomes the specified density, and after completion of the toner density changing process, an image forming ready state is set. It is characterized by doing.

According to claim 2 of the present invention, in claim 1,
The toner concentration changing process is performed by the toner concentration designating means 3
When the toner density is designated to be increased from 0, the control section 31 replenishes a predetermined amount of toner to the developing device 2 by the toner replenishing means 26 and 28 and detects the toner concentration by the toner density detecting means 25. And is repeated.

According to a third aspect of the present invention, in the first aspect,
The toner concentration changing process is performed by the toner concentration designating means 3
When the toner density is designated to be decreased from 0, the control unit 31 forms an electrostatic latent image on the image carrier 10 and then performs development by the developing device 2 and toner by the toner density detecting unit 25. It is characterized in that the concentration detection is repeated.

According to a fourth aspect of the present invention, in the second or third aspect, the control unit 31 performs the toner density detection after a predetermined time has elapsed after the toner replenishment or the development.

According to a fifth aspect of the present invention, in the first, second, third, or fourth aspect, the control unit 31 notifies the upper-level device 30 that transfers the image formation data of the image formation disabled state, The formable state is notified to the host device 30.

[0017]

According to the first aspect of the present invention, in response to the toner density change instruction, the image forming is disabled, the set toner density is changed to the designated density, and the toner density changing process is performed so that the toner density becomes the set toner density. When the toner density change is instructed, the image formation is enabled, so that image formation is prohibited when the toner density change instruction is issued, and when the specified toner density is reached, image formation is permitted, so the image specified from the first print The density output is obtained, and the image with the specified density can be output until the density is changed.

According to the second aspect of the present invention, when the toner density is designated to be increased, the toner replenishment and the toner density detection are sequentially repeated to gradually increase the toner density, so that the specified density can be accurately controlled.

According to the third aspect of the present invention, when the toner density is designated to be lowered, the electrostatic latent image formation / development and the toner density detection are sequentially repeated to gradually lower the toner density. Can be controlled.

According to a fourth aspect of the present invention, immediately after toner replenishment,
Immediately after development, the toner concentration of part of the developer locally rises or falls, so after the time required for the toner to be sufficiently stirred and uniformly dispersed in the developer, the toner concentration It is possible to accurately change the concentration by performing the detection.

According to the fifth aspect of the present invention, since the control unit 31 notifies the upper layer 30 of the image forming disabled state and the image formable state, the upper layer 30 is prevented from issuing useless image forming data when the image forming is not possible. it can.

[0022]

【Example】

(a) Description of an Embodiment FIG. 2 is a block diagram of a printer according to an embodiment of the present invention, and FIG. 3 is a block diagram of an embodiment of the present invention, showing a printer.

In FIG. 2, 10 is a photosensitive drum,
What is rotated by the drum motor M1 to form an image, 11 is a pre-charger, which pre-charges the photosensitive drum 10, 12 is a laser optical system, which modulates and drives a laser light source with a video signal, and a laser light source. Is optically scanned to linearly expose the photosensitive drum 10 to form an electrostatic latent image on the photosensitive drum 10.

Reference numeral 2 denotes a developing device, which is a developing roller 20 that conveys a developer consisting of carrier and toner to the photosensitive drum 10.
And agitating rollers 21 and 2 for agitating the developer in the developing device 2.
2, a blade 23 that regulates the developer layer thickness of the developing roller 20, and a stirring roller 2 that removes the developer removed by the blade 23.
Flow plate 24 for returning to 2, developing roller 20, stirring roller 2
And a developing motor M2 that rotates 1, 22.

The developing device 2 is further driven by a toner cartridge 26 containing toner, a stirring roller 27 for stirring the supplied toner, and a toner replenishing motor M3 to rotate to replenish the toner in the developing device 2. And a supply roller 28.

Reference numeral 13 denotes a transfer charger, which transfers the toner image on the photosensitive drum 10 developed by the developing device 2 onto the conveyed sheet, and 14 is a cleaner, which is the toner remaining on the photosensitive drum 10 after transfer. For collecting and cleaning the photosensitive drum 10, and 15 and 16 are conveying rollers for conveying the paper.

In FIG. 3, reference numeral 30 is a host device, which is composed of a computer or the like and outputs a print command, print image data, and a density designation signal, and 31 is a mechanism control unit of the printing device, which is composed of a microprocessor. The memory 31a has a density designation level, a density UP flag, a density DOWN flag, a control timer 1, and a control timer 2 in the memory 31a.

Reference numeral 32 is a high-voltage power supply, which controls the charging voltage of the pre-charger 11 and the developing bias voltage of the developing roller 20 under the control (VCDV, VBDV) of the mechanism control unit 31, and 33 is D / A ( A digital / analog converter for converting the sensitivity setting value DACD of the toner concentration sensor (magnetic sensor) 25 of the mechanism control unit 31 into an analog sensitivity setting value CNT and outputting it to the toner concentration sensor 25, and 34 is A / D (analog / digital) converter, which converts the detection amount TDO of the toner concentration sensor 25 into a digital detection value ADCD and inputs it to the mechanism control unit 31.

Reference numeral 35 is a self-printing circuit, which drives the laser light source of the laser optical system 12 in response to a self-printing instruction from the mechanism control section 31, and 36 is a video generation section, which is image data from the host device 30. In response to the,
A video buffer 37 generates a video signal, stores a generated video signal for one page, and modulates and drives a laser light source of a laser optical system.

FIG. 4 is a flow chart of the whole processing of one embodiment of the present invention, FIG. 5 is a flow chart of the density change start processing of one embodiment of the present invention, and FIG. 6 is a flow chart of the density UP processing of one embodiment of the present invention. FIG. 8 is a flow chart of density down / change end processing according to an embodiment of the present invention, and FIG. 8 is an explanatory view of density change operation according to an embodiment of the present invention.

Mechanism control unit (hereinafter referred to as processor)
31 performs initialization processing in response to power-on, issues a sensitivity setting value DACD of the toner density sensor 25, and sends the toner density sensor 2 through the D / A converter 33.
Set sensitivity of 5.

The processor 31 next checks the density UP flag in the memory 31a to determine whether the density UP processing is in progress.
When the processor 31 determines that the concentration UP process is being performed, the process shown in FIG.
The density UP process described later is performed, and the process proceeds to step.

If the processor 31 determines that the density UP processing is not being performed, it is determined whether the density DOWN processing of the memory 31a is being performed, and if it is determined that the density DOWN processing is being performed, the processing shown in FIG.
The density DOWN process described later in (A) is performed, and the process proceeds to step.

When the processor 31 determines that the density DOWN process is not being performed, the processor 31 determines whether there is a density UP instruction from the host device 30. When there is a density UP instruction, the processor 31 executes the density UP start processing of FIG. 5A, sets the density UP processing flag of the memory 31a to "1", adds "1" to the density level, The toner concentration detection interval of 10 seconds is set in the control timer 1, and the control timer 1 is turned on.

Next, the processor 31 causes the drum motor M
1 and the developing motor M2 are turned on, the photosensitive drum 10 and the developing device 2 are driven, and the charging voltage is applied to the pre-charging device 11 and the developing bias voltage to the developing roller 20 from the high-voltage power source 32, and the apparatus is operated. In the operating state, a WAIT status indicating that printing is not possible is issued to the host device 30, and the process proceeds to step.

When the processor 31 determines that there is no concentration UP instruction from the host device 30, it determines whether there is a concentration DOWN instruction. When the density DOWN instruction is issued, the processor 31 executes the density DOWN start processing of FIG. 5B, sets the density DOWN processing flag of the memory 31a to "1", and subtracts "1" to the density level, Control timer 1
The toner concentration detection interval is set to 10 seconds, and the control timer 1 is turned on.

Next, the processor 31 causes the drum motor M
1 and the developing motor M2 are turned on, the photosensitive drum 10 and the developing device 2 are driven, and the charging voltage is applied to the pre-charging device 11 and the developing bias voltage to the developing roller 20 from the high-voltage power source 32, and the apparatus is operated. In the operating state, a WAIT status indicating that printing is not possible is issued to the upper-level device 30, the printing start of the upper-level 30 is prohibited, and the process proceeds to step.

Next, the processor 31 determines that the host device 30
Other control processing such as printing processing is executed according to the instruction from, and the process proceeds to step. Next, regarding the concentration UP processing,
This will be described with reference to FIGS. 6 and 8A.

The processor 31 checks whether the toner replenishment control timer 2 in the memory 31a is on. If it is off, the process proceeds to step. If it is on, the timer 2 measures the set toner replenishment time (10 seconds). Check if it is "0".

If the timer 2 is not "0", the toner replenishment time has not elapsed, so the process proceeds to the step. If the timer 2 is "0", the toner replenishment time has elapsed. M3 is turned off, toner supply by the toner supply roller 28 is stopped, and the process proceeds to step.

Next, the processor 31 checks whether the toner concentration detection timer 1 is "0", and if it is not "0", the toner concentration detection interval has not elapsed, and therefore the process returns. If the toner concentration detection timer 1 is "0", the toner concentration detection timing has been reached, so the processor 31 reads the toner concentration of the toner concentration sensor 25 via the A / D converter 34, and specifies the detected toner concentration and the memory 31a. Compare with the concentration.

If the detected toner density has not reached the specified density, the processor 31 sets the toner replenishment timer 2 to "10" seconds, turns on the toner replenishment timer 2, and sets the toner concentration detection timer 1 to " Set 20 "seconds,
Toner concentration detection timer 1 is turned on and toner replenishment motor M
3 is driven to start toner replenishment by the toner replenishing roller 28, and the process returns.

Therefore, as shown in FIG. 8A, the toner is replenished for 10 seconds and the toner density is detected after 20 seconds. On the other hand, when the detected toner density reaches the specified density in step, the processor 31 performs the density change end processing of FIG. 7B and returns.

That is, the processor 31 sets the density UP processing flag and the density DOWN processing flag in the memory 31a as follows.
"0" is set, the control timers 1 and 2 are turned off, the drum motor M1 and the developing motor M2 are turned off, and the high voltage power source 32
Then, the application of the charging voltage of the pre-charger 11 is turned off, and the application of the developing bias voltage of the developing roller 20 is turned off.

The processor 31 is connected to the host device 30.
The WAIT status of is canceled and printing can be started from a higher level. Next, regarding the density DOWN processing,
This will be described with reference to FIG.

The processor 31 measures whether the toner concentration detection timer 1 of the memory 31a is "0" by measuring the toner concentration detection interval (5 seconds). If it is not "0", the toner is detected. Since it has not reached the concentration detection time,
To return.

When the toner concentration detection timer 1 is "0", the processor 31 has reached the toner concentration detection time, so the toner concentration of the toner concentration sensor 25 is read and detected via the A / D converter 34. The toner density is compared with the designated density of the memory 31a.

If the detected toner density has not reached the specified density, the processor 31 sets the toner density detection timer 1 to "5" seconds, turns on the toner density detection timer 1, and activates the self-print circuit 35. And then return.

As a result, the self-printing circuit 35 drives the laser light source of the laser optical system 12 for 1 to 2 seconds, the photosensitive drum 10 is exposed, the developing device 2 develops the toner, and the toner is consumed.

On the other hand, when the detected toner density has reached the specified density in step, the printer 31 causes the printer 31 shown in FIG.
The density change end process is performed and the process returns. That is, the processor 31 sets “0” in the density UP processing flag and the density DOWN processing flag of the memory 31a, turns off the control timers 1 and 2, and sets the drum motor M1 and the developing motor M.
2 is turned off, the application of the charging voltage of the pre-charger 11 via the high voltage power supply 32 is turned off, and the application of the developing bias voltage of the developing roller 20 is turned off.

The processor 31 is connected to the host device 30.
The WAIT status of is canceled and printing can be started from a higher level. In this way, the apparatus is set to the WAIT state in accordance with the toner concentration UP instruction, toner is supplied for 10 seconds as shown in FIG. 8A, and the toner-supplemented developer is sufficiently stirred. After 20 seconds, the toner density is detected, and it is determined whether the specified density is reached. If the specified density is not reached, toner supply and toner density detection are repeated again, and when the toner density reaches the specified density, the WAIT state is reached. Is released to enable printing.

Further, the apparatus is set to the WAIT state according to the toner density DOWN instruction, and as shown in FIG.
If the density is detected and the specified density is not reached, the self-printing operation is performed, the toner is consumed, and the toner density is detected 5 seconds after the developer whose toner has been consumed is sufficiently stirred, and the self-printing is performed. Whether or not it is possible is judged, and when the specified density is reached, the WAIT state is released and printing is enabled.

Therefore, according to the toner density change instruction, printing is prohibited until the toner density reaches the designated density, and when the designated density is reached, printing is permitted, so that the printing from the first sheet can be performed with the designated density. You can continue printing with the specified density until the density is changed.

Further, since toner replenishment or toner consumption and toner density detection are repeated, fine density setting can be performed accurately. Furthermore, since the toner concentration is detected after a lapse of a certain stirring time after the toner is replenished or consumed, the toner concentration can be accurately detected by the agitated developer, and the change to the designated concentration can be made accurately.

(B) Description of Other Embodiments In addition to the above embodiments, the present invention can be modified as follows. In the above-described embodiment, the printing mechanism has been described as an electrophotographic mechanism, but the invention can be applied to a developing mechanism that develops a toner image on another printing mechanism (for example, an electrostatic recording mechanism).

The toner density is set to 1 by specifying the toner density.
Although the step is changed, the designated density value may be designated. Although the toner density is designated from the host program or the operation panel, it may be designated from the operation panel of the printing apparatus or the like.

Although the image forming apparatus has been described as a printer, it can be applied to other image forming apparatuses such as a copying machine and a facsimile. Although the toner concentration is detected by the magnetic sensor, the present invention can be applied to the one in which the toner mark is formed on the photosensitive drum and is optically read.

The present invention has been described above with reference to the embodiments.
Various modifications are possible within the scope of the invention, and these modifications are not excluded from the scope of the invention.

[0059]

As described above, according to the present invention,
It has the following effects. In response to the toner density change instruction, the image forming disabled state is controlled to be changed to the designated density, and when the designated density is reached, the image forming is made possible, so that the image forming of the designated density is possible from the initial stage of image formation.

Since the toner density is controlled by changing the toner density by instructing the toner density change, the image formation of the toner density can be continued unless the toner density is changed.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a configuration diagram of a printing apparatus according to an embodiment of the present invention.

FIG. 3 is a block diagram of an embodiment of the present invention.

FIG. 4 is a flowchart of the entire processing according to an embodiment of the present invention.

FIG. 5 is a flow chart of a density change start process according to an embodiment of the present invention.

FIG. 6 is a flow chart of concentration UP processing according to an embodiment of the present invention.

FIG. 7 is a flow chart of concentration DOWN / change end processing according to an embodiment of the present invention.

FIG. 8 is an explanatory diagram of a density changing operation according to an embodiment of the present invention.

[Explanation of symbols]

 2 developing device 10 photosensitive drum (image carrier) 11 pre-charging device 12 laser optical system 20 developing roller 25 toner concentration sensor 28 toner replenishing roller 30 upper device 31 mechanism controller M1 drum motor M2 developing motor M3 toner replenishing motor

Claims (5)

[Claims] 1. An image carrier (10) and an image carrier (10)
Latent image forming means (11, 12) for forming an electrostatic latent image on the
A developing device (2) for developing the electrostatic latent image on the image carrier (10) with a developer, a toner replenishing means (26, 28) for replenishing the developing device (2) with toner, and the developing device ( The toner replenishing means (26, 28) is controlled by comparing the toner concentration detecting means (25) for detecting the toner concentration of 2) with the detection output of the toner concentration detecting means (25) and the set toner concentration. An image forming apparatus having a control unit (31) is provided with a toner concentration designating unit (30) for designating the toner concentration of the developing device (2), and the control unit (31) includes the toner concentration designating unit (30). ), The image forming disabled state is set in accordance with the change of the toner density being specified, and the set toner density is changed to the specified density, and the toner density detecting means (25)
The toner concentration control method is performed so that the detection output of the above becomes the specified concentration, and after the toner concentration change process is completed, the image forming ready state is set. 2. In the toner density changing process, when the toner density designating means (30) instructs to increase the toner density, the control section (31) controls the toner replenishing means (26, 28). 2. The toner concentration control method according to claim 1, wherein replenishment of a predetermined amount of toner to the developing device (2) and toner concentration detection by the toner concentration detection means (25) are repeated. 3. The toner concentration changing process, when a toner concentration lowering instruction is made by the toner concentration designating means (30), the control section (31) causes the image bearing member (1)
2. The electrostatic latent image is formed on 0), and then the development by the developing device (2) and the toner concentration detection by the toner concentration detection means (25) are repeated.
Toner concentration control method. 4. The toner concentration control method according to claim 2, wherein the control unit (31) performs the toner concentration detection after a lapse of a predetermined time after the toner replenishment or the development. 5. The host device (30) for transferring the image forming data to the image forming impossible state by the control unit (31).
To the upper device (3
0) is notified to claim 1 or 2 or 3
Or the toner density control method of 4.