JPH0497183A - Toner density control method - Google Patents

Abstract

PURPOSE:To prevent toner which is not electrostatically charged because of the excessive supply of toner from being caused when a developing unit is started to be used and the surface staining of a photosensitive drum by reducing a toner replenishing time till a specified time that the replenishing quantity of toner is stabilized and gradually increasing and controlling the time so that the specified toner replenishing time may be attained. CONSTITUTION:In the case of controlling toner concentration in a system in which the exchanged developing unit 6 is used, a detecting member for detecting an unused state is provided in the unit 6 and a control means for counting and cumulating the replenishment of toner which is performed simultaneously as the unit 6 is started to be used as time is provided. Then, the toner replenishing time is altered in accordance with the counted and cumulated time for the fixed time that is from an unused state to starting the use of the unit. In the case of altering the toner replenishing time, the time is gradually increased till the fixed time elapses from starting the use so that the specified toner replenishing time is attained when the fixed time elapses after starting the use. Thus, the toner which is not electrostatically charged because of the excessive supply of the toner is prevented from being caused when the unit 6 is started to be used and the surface staining of the photosensitive drum 4 caused by the toner which is not electrostatically charged is prevented.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to toner concentration control in a replaceable developing device using a two-component developer used in a recording device such as an electrostatic recording type copying machine. It is about the method.

[Conventional technology]

In an electrostatic recording type recording apparatus, an electrostatic latent image corresponding to an image to be recorded is formed on the surface of a photoreceptor, and toner from a developing device is attracted to this electrostatic latent image to form a visible image.

When using a dry two-component developer consisting of resin-coated iron powder (hereinafter referred to as developer) and powder toner (hereinafter referred to as toner) as this developing device, the toner has characteristics opposite to those of the photoreceptor. The electrostatic latent image formed on the photoreceptor is adsorbed by friction with the developer so as to be electrically charged.

When toner is consumed during the developing operation and the ratio of developer to toner in the developing device, that is, the toner concentration in the developer decreases, toner is replenished from the toner replenishment tank and the toner concentration in the developer becomes constant. It is controlled as follows.

As this control method, a reference density pattern is provided at the edge of the document reading surface, this pattern is read together with the document by a scanner, an electrostatic latent image corresponding to the read image is formed on the photoreceptor, and this electrostatic latent image Develop it into a visible image.

The light reflectance of the visible image of this reference density pattern and the light reflectance of the photoreceptor surface (non-image area) are detected by a reflective optical sensor, and the toner is detected according to the ratio of the two light reflectances. A control method is used to control replenishment and determine the presence or absence of toner.

In recent years, developing devices have been downsized and disposable developing units that integrate the developing section and toner cartridge section and can be replaced with a toner end have been adopted. The amount of developer accommodated is reduced, and therefore the ratio of the amount of toner replenished to the developer is increased.
The amount of uncharged toner that is insufficiently stirred increases, and problems such as scumming and toner scattering are more likely to occur.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner concentration control method that is compatible with the use of a small, replaceable developing unit, in which the amount of developer contained in the developing unit is small and the amount of developer is replenished. A method for controlling toner concentration in a developing unit in which the ratio of toner amounts is increased is provided, and it is possible to easily prevent scumming, toner scattering, etc. that occur on the surface of a photoreceptor.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a recording device in which a document image is exposed on a photoreceptor to form a latent image, the latent image is developed in a developing device, and a toner image is transferred to a transfer paper. In the toner concentration control method using a developing unit that is replaced when the toner runs out as the developing device, the developing unit is equipped with a detection member capable of detecting an unused state, and a toner replenishment device that operates when the developing unit starts to be used. The present invention is characterized in that the toner replenishment time is changed according to a certain period of time from an unused state to the start of use, and the cumulatively counted time, and the toner replenishment time is changed according to the cumulatively counted time. The time change is
It is characterized in that the toner replenishment time gradually increases after a certain period of time from the start of use so that a predetermined toner replenishment time is reached after a certain period of time from the start of use.

[Effect]

According to the configuration of the present invention, toner concentration control of a developing unit that is replaced when the toner runs out is performed by shortening the toner replenishment time over a predetermined period of time during which the toner replenishment amount is stabilized based on the signal from the detection member at the start of use of the developing unit. , gradually increases the toner replenishment time to a predetermined toner replenishment time, and prevents the generation of uncharged toner due to oversupply of toner when the developing unit starts to be used, and the background stains on the surface of the photoreceptor drum caused by this generation. It is suitable for toner concentration control of a small developing unit that can be prevented and replaced.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a schematic cross-section of one type of copying machine to which the small replaceable developing unit of the present invention can be applied.

In this copying machine, a scanning optical system 2 consisting of an exposure lamp, a reflective mirror, and a lens is arranged below a contact glass l on which a document can be placed, and a reference density pattern 3 is located at the left end position of the lower surface of the contact glass 1. is provided, consisting of a black patterned sheet having a predetermined light reflectance.

A charging charger 5, a developing unit 6, a transfer/separation charger 7, and a cleaning unit 8 are arranged around the photoconductor drum 4, and a reflective photosensor is disposed between the transfer/separation charger 7 and the cleaning unit 8. 9 is provided facing the photoreceptor drum 4, and a static elimination lamp 13 is provided behind the cleaning unit 8.
14 is a main body drive motor as a main motor.

Light from the exposure lamp of the reciprocating scanning optical system 2 is reflected on the surface of the document, and an image is formed on the photoreceptor drum 4 via the optical system of the scanning optical system 2.

The electrostatic latent image formed on the photoreceptor drum 4 is converted into a facial image by toner in the developing unit 6 according to its potential distribution. The visible image corresponding to the facial image of the document is transferred to the transfer paper from the paper feed section 10 at the transfer position of the transfer/separation charger 7, and the transfer paper to which the visible image has been transferred is transferred to the photoreceptor drum 4.
The toner is separated from the sheet, the fixing device 11 heat-fixes the toner, and the toner is discharged to the paper discharge section 12.

A means for controlling the toner density within the developing unit 6 will be explained.

The reference density pattern 3 forms a latent image on the photoreceptor drum 4 using light from the exposure lamp of the scanning optical system 2, and is converted into a facial image using toner from the developing unit 6. The toner image is transferred to the reflective photosensor 9. Read by.

As shown in the circuit of FIG. 2, the reflective photosensor 9 is composed of a light emitting diode and a phototransistor, and the amount of light from the light emitting diode can be adjusted by a variable resistor VR, and the light emitting diode is controlled by a main controller. Board CP
U controls the lighting on and off.

When the light emitting diode is turned on, the density of the area on the photoreceptor drum where toner is not attached (non-image area) is adjusted so that the output signal of the phototransistor is 4■, and the CP
It is taken into the CPU via the U's A/D converter.

Density (
Vo) is related to the surface condition of the photoreceptor drum, and at the beginning of use, there are no scratches or thin lines caused by use, and it is 4V, but in what is called a runaway mode.
In a state where toner replenishment is performed continuously regardless of toner concentration, this value will vary from 4 to 3 due to toner scattering, etc.
．． It shows a decreasing tendency to 5■.

Similarly, the toner image based on the reference density pattern is also sent to the CPU via the A/D converter of the CPU as an output signal of the phototransistor by the operation of the reflective photosensor 9.
be taken in. The density, which is the light reflectance of the toner image based on this reference density pattern, is expressed as Vl.

Compare the density (Vo), which is the light reflectance of a portion of the photoreceptor drum to which no toner is attached, with the density (V,), which is the light reflectance of the toner density due to the reference density pattern portion of the photoreceptor drum. By doing this, toner supply is controlled.

In other words,■. ≦V, x8 (When V0=4y, ■,
≦0.5V), the toner replenishing solenoid is energized for a predetermined period of time, and the toner in the toner hopper section 16 is replenished into the developer cartridge case section 15 in the developing unit 6 shown in FIG.

When Vo>V, x3, the toner replenishment solenoid is not energized and no toner replenishment operation is performed.

As described above, conventional toner density control means binary-discriminates the light reflectance of the photoreceptor drum surface and the light reflectance of the toner image of the reference density pattern formed on the photoreceptor drum. Controls on/off of toner supply.

Furthermore, even if the sensor output on the part of the photoreceptor drum to which no toner is attached is actually set to 4■, if uncharged toner gets around to the developing roller during toner replenishment, , it drops to about 2.5 to 3.5V, and therefore, even if you replenish toner, the toner concentration does not increase.
The toner replenishment mode may not turn off and may go out of control.

After determining the light reflectance of the surface of the photoreceptor drum and the light reflectance of the toner image of the reference density pattern formed on the photoreceptor drum, the toner image of the reference density pattern on the photoreceptor drum is transferred to a cleaning unit. The charge is scraped off by the blade 8, and the charge is removed by the charge removal lamp 13, and the photosensitive drum 4 is charged for the next copying process.

This toner concentration control operation is performed at intervals of 15 copies, and the on mode of the toner replenishment clutch is kept on for a predetermined period of time for each copy.

The small replaceable developing unit 6 used in the present invention will be explained with reference to FIG.

The developing unit 6 has a structure in which a developing cartridge case section 15 and a toner hopper section 16 are integrated.
When the toner runs out, each developing unit is replaced.

Inside the developer cartridge case part 15, a developer roller 1 is provided with a built-in fixed stone group for visualizing the latent image on the photoreceptor drum.
7. A developer stirring paddle 18 that stirs the developer in the case portion 15, a doctor 19 that regulates the amount of developer pumped onto the surface of the developing roller 17, and a developer regulated by the doctor 19 on the paddle side. It is equipped with a separator 20 for returning to the original state. The developer cartridge case portion 15 is filled with 200 g of developer.

The toner hopper part 16 includes an agitator 21 that stirs the toner in the toner hopper and replenishes the toner to the developer cartridge case 15, and a mylar 22 with small holes that regulates the amount of toner supplied to the developer cartridge case. A portion of the toner hopper is filled with 300 g of toner.

The agitator 21 is driven by turning on/off the toner replenishment clutch.
Operated by off control.

Next, regarding the relationship between the remaining amount of toner in the toner hopper part 16 and the toner replenishment amount, as shown in FIG. is about 20 g/min (after that, it is 12 to 1 g/min until the toner end is reached).
It is stable at 4g/min.

Further, the developing unit is replaceable, and immediately after being replaced, it is necessary to stir the developer in the developing cartridge and the case section 15 for a predetermined period of time to increase the amount of charge.

For this reason, the developing unit is provided with a detection member that can determine the usage state of the developing unit, that is, whether or not the developing unit is unused.

FIG. 5 shows the configuration of the detection member. That is, a threaded part 24a is formed on the shaft part 24 which is interlocked with the shaft of the paddle 18 that stirs the developer in the developer cartridge case part 15 by gears 23a and 23b, and a retaining part 25a is screwed into this threaded part 24a. A light shielding member 25 having a shape is attached. The tip 25 of the light shielding member 25 is shown in FIG.
As shown in FIG. 1, before the development unit is used, the initial unit sensor 26 supported by the development cartridge case is placed in a position that shields it from light.

Therefore, in the initial state of the developing unit, the tip 23b of the light shielding member 23 shields the initial unit sensor 24, and the sensor output becomes an "H" signal. When the developing unit is used, the developer in the developing cartridge case is stirred, so that the light shielding member 23 is in the fifth position.
As shown in FIG.
When the sensor leaves the position, the sensor output becomes "L".

FIG. 6 shows a flowchart of the present invention regarding toner concentration control at the beginning of use of the developing unit based on the initial development detection signal from the light shielding member 23 and the initial unit sensor 24.

After setting an unused developing unit into the copier main body, turn on the power.

When the power is turned on, after executing predetermined processes such as clearing the read/write memory RAM, initializing various mode settings, and 5ms internal interruption, initial development detection is output from the development unit. Check.

When this output signal is "H", it is assumed that an unused developing unit (initial developing unit) has been inserted, and the developing toner replenishment timer stored in the non-volatile RAM shown in FIG. When the state is enabled (warm-up), the main motor is turned on, and the paddle of the developing unit is idled for one minute to build up the charge on the developer.

In this embodiment as well, the detection operation for toner density control using the reference density pattern is performed once every five copies.

When the start key is pressed in the copy-enabled state, the main motor is driven, activates the toner sensor detection counter, and detects the light emitting diode (toner sensor) of the reflective photo sensor once every five copy processes. LED).

When the output of the reflective photosensor is 2.5 V or less (an intermediate level value between the light reflectance of the surface of the light body and the light reflectance of the toner image of the reference density pattern), the output of the sensor is reduced for 5 ms. 16 times at every interval, and the average value of the latter 8 times is stored in a register as an average value DBV corresponding to the light reflectance of the toner image of the reference density pattern on the photosensitive drum.

Next, when the output of the toner sensor becomes 2.5V or more, as in the case of the above detection, it is read 16 times every 5ms, and the average value of the latter 8 times is used as the light reflectance of the photoreceptor surface. Store it in the register as the corresponding average value DBVSG.

Then, V, (DBVSP)X8>Vo (DBVSG
), the toner replenishment request flag F is set to "1".

At the toner replenishment timing, the toner replenishment clutch is turned on for a predetermined period of time, and the agitator is operated to supply a predetermined amount of toner to the developer cartridge case. , Since 100% of toner is contained in the toner amount/flange, the value of the toner replenishment timer is checked, and for a certain period of time from the start of use of the developing unit until the toner supply amount becomes stable. Adjust the toner supply amount.

In this embodiment, the toner replenishment timer is 120 seconds.
When it is less than ec, the toner replenishment time, which is the connection time of the toner replenishment clutch, is 1 sec, and it is 120 to 240 sec.
When c, toner replenishment time is 1.5 sec, 240 s
ec or more, the normal toner replenishment time is 2 se
c.

The developing unit that has been in use for more than 240 seconds has already started a copy operation, and the toner replenishment request flag F has been set.
If the toner replenishment time is set to “1”, the toner replenishment time will be the normal 2
sec becomes on state.

Therefore, when a developing unit is newly installed in a copying machine, the amount of toner supplied from the toner hopper is limited until the developer is stirred in advance and given sufficient charge, and the toner supply is stabilized from the start of use. , the toner replenishment time is made shorter than the regular toner replenishment time, and adjusted by increasing it gradually.

Therefore, it is possible to prevent toner scattering, background smearing on the photoreceptor drum, etc., which are caused by fluctuations in the amount of toner replenishment at the start of use when the developing unit is replaced.

Also, Vl (DBVSP)X8≦Vo (DBV
sc), the toner replenishment request flag F is reset to "0", the toner replenishment clutch remains off until the next toner detection timing, and toner is not replenished.

〔effect〕

According to the configuration of the present invention, as a toner density control method for a developing unit that is replaced when the toner runs out, the generation of uncharged toner due to excessive supply of toner at the beginning of use of the developing unit, and the occurrence of uncharged toner on the surface of the photoreceptor drum due to this generation. It prevents background smearing and is suitable for controlling toner concentration in a small, replaceable developing unit.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a copying machine to which the present invention can be applied, FIG. 2 is a block diagram showing a circuit related to toner concentration control, and FIG. 3 is a developing device used in the present invention. A schematic cross-sectional view of the unit. Figure 4 is a graph showing the relationship between the amount of toner in the pump and the amount of toner replenishment in a small developing unit. Figures 5 (a) and (b) show whether the developing unit is used or not. FIG. 6 is a schematic cross-sectional view showing an embodiment of the detection means for detecting the state of use. FIG. 6 is a flowchart showing the toner concentration control method of the present invention. ■...Contact glass, 2...Scanning optical system, 3.
... Toner density control pattern, 4... Photosensitive drum, 5... Charger, 6... Development unit,
7... Transfer/separation charger, 8... Cleaning unit, 9... Reflective photosensor, 10... Paper feeding section, 11... Fixing device, 12... Paper discharge section, 13.
... Static elimination lamp, 14... Main motor, 15...
Developing cartridge case section, 16... Toner hopper section, 17... Developing roller, 18... Paddle, 19...
・Doctor 20... Separator, 21... Agitator, 22... Mylar with small holes 23a, 23b... Gear, 24... Light shielding member guide shaft portion, 24a... Threaded portion, 25... - Light shielding member, 25a... engaging portion, 25b.
... Light shielding member tip, 26... Initial unit sensor. (G) Section (b)

Claims (2)

[Claims] (1) In a recording device in which a document image is exposed on a photoreceptor to form a latent image, the latent image is developed in a developing device, and the toner image is transferred to transfer paper, the developing device is replaced when the toner runs out. In a toner density control method using a developing unit, the developing unit is equipped with a detection member capable of detecting an unused state, and a control means is provided for cumulatively counting toner replenishment as time when the developing unit starts to be used. 1. A toner concentration control method comprising: changing a toner replenishment time according to cumulatively counted time during a certain period of time from an unused state to the start of use. (2) The change in the toner replenishment time is gradually increased after a certain period of time from the start of use so that a predetermined toner replenishment time is reached after a certain period of time after the start of use. The toner density control method according to item 1.