JPS58221857A - Image density controlling method - Google Patents

Abstract

PURPOSE:To control image density rapidly and accurately, by partially forming surface potential of almost 0 V little affected by charging and exposure characteristics, and attaching toner there. CONSTITUTION:When a density detecting circuit 26 is turned on with a timing generating circuit 25 and voltage is applied from a power supply 29 to a reverse charger 30 by changeover of power, since a shielding plate 31 is provided before a corona wire 30b, the surface of a photoreceptor 1 is charged separately to potential reverse to normal charging polarity on one part, and to almost 0 V potetial on the part shielded with the plate 31. On the other hand, the contact point of a developing roll 17 is changed over to 32b to connect a bias voltage source 34 equal in polarity to the reversely charged part on the photoreceptor 1, and the toner is attached only to the 0 V part on the photoreceptor 1. An amt. of toner attached is detected with a detector comprising a light emitting element 6 and a photodiode 7, and when it is smaller than the reference value, toner concn. in a developer is raised and when it is not raised in spite of these measures, other factors of development characteristics are checked and restored to good condition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the density of one image per image, and particularly to a method for dividing a developed image into one area in an electrophotographic apparatus or a still recording apparatus.

As is well known, in electrophotographic devices and electrostatic recording cameras, an electrostatic latent image is formed on an image carrier such as a photoreceptor or a rotor. Boundary 1 (to) due to colored particles? First, an image is created.

It is known that the preparation of the reproduced toner image at this time depends on many factors.

Typically, it depends on the degree of toner in the developer.

The developer normally used in such image forming apparatuses is called a two-component developer, and is composed of two components: toner and carrier. The carrier triboelectrically charges the toner to a predetermined polarity. , has the role of adsorbing Jl and transporting it to the negative development position. il'J image position b゛niriii-(G-1'
,, Only the toner is not attracted to the electrostatic property 1), and it stands still.
? The current I family of ``Sieve F Shizuka'' is row f (wa J. For this reason, the current F
By repeating this process, the toner density on the scoop and image side decreases.

If development is performed using a developer with such a reduced density, the developed toner image will naturally have a low density. Therefore, a method has been developed in which the toner concentration in the developer is always adjusted appropriately by measuring the amount of toner applied to the image area once in each image. Examples of such methods are Japanese Patent Publication No. 43-16199 and Japanese Patent Publication No. 43-16199.
No. 8-29448,! 1 is also No. 1963-3'6341,
ta 1977-22642, JP 50-125.7
No. 45 is not shown in the publication. In the conventional methods such as these, a toner adhesion area for foot measurement is provided on the surface of the photoreceptor outside the normal copying area, and a predetermined charge is applied to this area to adsorb the toner. However, the disadvantage is that the photoreceptor is large. In addition, an image of a standard density plate placed outside the normal copying area of the photoreceptor, for example, on the back side of the tip of the document plate, is fogged to form a latent image in the same manner as a normal document, and this latent image λ1 is υ−
I don't know how to determine the current publication of 5 images.
In this method, if the toner concentration in the developer is controlled based on the measured results, undesirable results may occur.For example, the amount of toner in the toner layer is low. In this case, even if new toner is replenished into the 91. image side, there is no problem if the cause is truly a decrease in the toner concentration in the St developer, but if there is insufficient charging due to deterioration of the charger or photoreceptor, there is no problem. If the cause is overexposure due to pressure fluctuations, the toner concentration will become too high, causing background stains.
1 or may cause problems such as toner scattering.

In this way, the density of the developed image, that is, the density of the toned image, is
Typically, it depends on the toner concentration in the developer, but other factors such as the amount of charge, amount of light, and photoreceptor! Hr' I raw, rice imager η゛note, current 1 fan bias 4, toner band:
i]ir,su2. Various factors such as intermittent cap and development time are involved. Therefore, if you immediately replenish the toner even when the toner level has decreased, the above-mentioned problems may occur. Also,
Recently, single-component products consisting only of toner have been introduced! When using developer, different types of toners may be mixed together, or cooled/ill mixed toners may be used at ℃, so it is necessary to control the component composition of the developer.
, The artillery of the insertion gap is tli! There are members of the same group who perform the I-go.

The object of the present invention is mainly to improve
li! It is an object of the present invention to provide a method for maintaining an appropriate image density of 4 by detecting a change in image yield and controlling the first cycle during development based on the detection result. Development characteristics include toner concentration in developer, toner charge amount, iJ
? , 1, the amount of applied bias, the developing time, the developing gear knob between the developing sleeve and the photoreceptor, the rotation period of the developing sleeve, and all other factors that are intervening in the developing process. The method according to the present invention is to reduce the surface of the image carrier with a diameter of 1M.
It is used for 3 minutes and the normal production process.
applying a voltage of the same polarity as this reverse itf voltage to the 7 electrodes to cause the toner to adhere to the zero potential portion of the image carrier surface;
and measuring the incoming toner 1. With this invention
For example, since the toner is attached to the image carrier surface by utilizing the saturated residual potential near zero V, where the image carrier surface potential is most stable, it is possible to prevent the image from changing due to custom charging or changes in the AV optical special note. Concentration changes can be excluded, Hu, statue! P1: Rapid and accurate control only for changes in pregnancy.

Image density change 11 can be carried out.Hereinafter, this invention will be explained as b) with reference to Fig. 1.

Figure A□1 shows an example of an electrophotographic apparatus to which the imi I# density control force method according to the present invention is applied. A charger 2, a chaotic optical system 3, an eraser/g 4, a QI device 5, and a light emitting element 6 for detecting toner 41 are installed around the backlight drum 1 in the counterclockwise direction of rotation. and 7. A transfer charger 8, an electrostatic layer device 9, a static elimination charger 10, a static elimination lamp 11, a cleaning device 12, a reverse charging charger 30, etc. are arranged,
! There are 1. First, the front surface of the plastic drum 1 is uniformly charged by the charger 2, and then the path light optical system 3 is attached thereto. The original to be photographed is irradiated with 1ψ of light of 1 angle J' (, the charge on the photoreceptor is erased with a low weight), and then there is 0↑ 1ψ corresponding to the IM image. The house is J Hi 1. This Aoko Den 7th floor 1 elephant is gF jj @
It will be developed and developed. The device 5 includes a container J4 containing a two-component developer 13 consisting of toner and a magnetic carrier, and in the process of stirring and pumping by an impeller J5 and pumping by a second roller J6. , the toner is even charged to a polarity opposite to that of the electrostatic potential due to friction with the carrier. After both have been pumped up and transferred from the roller 6 to the developing roller 7, only the toner is attracted to the Shizukiura 1W at a position close to the photoreceptor and development is performed. After development, the developer on the developer roller 7 is scraped off from the developer roller 17 by a scraper 18. In a normal copying cycle, the toner or toner obtained by development is transferred from the paper feed port 19 to the paper feed roller 20° (1
1ii) By superimposing the toner on the transfer paper 23 fed by the feed rollers 21 and 22, and supporting a band having a polarity opposite to that of the toner charging electrode caused by the transfer charger 8.

The image is transferred onto the transfer paper 23. After the transfer, the transfer paper 23 is separated from the surface of the photoreceptor and enters a fixing device 9 where the transferred toner image is fixed, and is discharged onto a tray 24.

On the other hand, residual charges are removed from the photoreceptor after the transfer by the charger JO and the charger J1.

The residual toner is removed by a cleaning device 12.

In order to perform image density 1t control in this electrophotographic apparatus, first, the timing generation circuit 25 turns on the manufacturing detection circuit 26, sends a signal to the charge control i'+1i11 circuit 27, and starts the charger from the power supply 28. 2
The power supply 29, which has a polarity opposite to that of 1+, switches from supplying power to the reverse charger 30. As shown in FIG.
1 that is corona wire 30b O) 1iiJ direction a
A shielding plate 31 is provided so that the corona discharge current is shielded from the WB.
(1) The surface of the light body (1) is not used in the normal production process, and is shielded by the upper part of the light body (1), which has a polarity opposite to that of the Teiza pole (1), and the shielding plate (31), which is also at almost zero potential. Charge A1 separately.

At the same time as this switching of the charging electrode 1, the switch 32 for switching the insulator source for the developing roller J7 is activated by a signal from the timing generating circuit 25fJ to switch the charging electrodes 32a to 32b. can be switched to. 1 for the contact 32a1111), and the insulator source 33
5. During the normal production process, the developing roller 17, which also serves as a developing electrode, is formed on the photoconductor at a potential slightly higher than the potential of the surface of the photoreceptor. , Koneto I-cho (Kuiasumi ridge, which has the opposite polarity to the 1st generation, that is, the 11th generation of the toner) is applied.
As a result, background development on the photoreceptor is inhibited (11), and background stains on copies are prevented (λ'1). In contrast to this A1, on the 32b side, there is a 11. Due to this 1, the tree attaches only to the zero potential part above the sensitive body.

At this time, σ〕Reverse angle (Ias angle) assumes that the toner charging electrode i is negative.

Set the potential of the oppositely charged part of the second light body to -500V or more, Mari Riko, <&';l--500V anno・1-)-8
The range of -200 to -400V is most effective with respect to the target placement on the photoreceptor and with respect to density measurements.

In this way, the toner that has been emitted at the zero degree level on the photoconductor is then transferred to the light emitting element 6 and the receiving "0" element 7.
Detected by a detection device including: In other words, light from a light emitting element 7 such as a lamp or a light emitting diode is reflected on the surface of the photoreceptor, and the reflected light is received by a light receiving element 7 such as a photodiode. Let's go. At this time, the change in the optical power received due to the toner adhesion is extracted as an electrical signal and compared with the electrical signal indicating the reference amount of IjN at 1'1 and 26'. '1, then σ] The size of the toner addition area is detected A. Based on the detection result at this time, for example, if the amount of toner stored is less than the one standard for toner replenishment fl.
Drive the former IW 1st road 35, visit the current IW monk 5, and paste one full plate of toner in the bukotopu spicy device 36 into the current Iga container 74[)E. interpretation 1 home remedy 13
Increase the toner concentration inside. After doing this, add the toner to 117, then add the toner to 1.
, Despite the fact that Tori-rei # 凰hゝノ□white.

If there is no addition of ℃, it can be determined that the cause is not a lack of toner in the developer, and other development factors such as toner charge amount, development bias amount, development time, development gap, development roller Check and adjust the rotational speed malleability of 7.k.

In the above example, a corona charger 3o for reverse charging the photoreceptor in 1iii image density control is specially prepared, but the charger 2 in a normal image forming process can also be used as this charger 3o. Zupuzuwachi,
As shown in Figures 1 and 3, partially insert +f 5 shielding plate 31' into the discharge opening of charger 2'.
In addition, the electric power source 21't, 29 applied to the charger 2' can be selected by the fi electric control circuit 27'. Then, in the normal process, the charger 2' is connected to the power source 28 and the shielding plate 31'&'j is left open.When performing image density control, the charger 2' Connect to power supply 29.

The discharge opening of the charger 2' is partially blocked by the shielding plate 31'. By this Jl, 1 song 1! II K fl
At the time on the J side, a zero tit portion and a cover portion are formed on the light body 1.

As described above, according to the present invention, a surface potential of approximately zero V, which is less affected by charging tVj characteristics and custom exposure, is partially formed on the surface of the tW light body, and toner is attached thereto. Changes in fN can be understood almost as changes caused by custom development, and wasteful consumption of toner can be prevented and image density control can be performed more quickly and accurately.

Although this invention has been described above in accordance with the specific embodiments shown in the drawings, this invention is capable of various modifications, and all modifications within the spirit of this invention as set forth in claims i. It is included in this invention.

[Brief explanation of the drawing]

Figure 1'1 is a schematic diagram showing an example of an electrophotographic temporary storage to which the image density control method according to the present invention is applied, Figure 2 is a schematic sectional view showing an example of a charger for reverse charging, and Figures 3 and 3. is a schematic diagram showing only ai 1'i++ of another example of an actual gun of the present invention. 1... Photosensitive drum, 2... Teiasahi charger, 17
...Developing roller, 30...Reverse charger, 3
1... Shielding plate, 36... Toner supply device-4α

Claims (1)

[Claims] 1. An image forming method comprising forming an image carrier and imaging an electrostatic latent image with toner on a developing electrode, wherein the surface of the image carrier is The toner is charged separately into a potential part of zero volts and a potential part of opposite polarity to the charging potential used in the normal image forming process, and a voltage of the same polarity as the opposite charging potential is applied to the developing electrode to charge the toner. Detecting the +J amount of the toner adhering to the zero volt potential portion of the surface of the carrier, and detecting the +J amount of the toner adhering to the zero volt potential portion of the surface of the carrier. Image density Ha including filling the upper toner-attached image density.
ll FA1 method. 2. The image f7 density control method according to claim 311, wherein the divided charging τ is performed by a reverse charging corona charger that shields a part of the corona emission region. 6. The above-mentioned separate charging is carried out by switching the polarity of the voltage applied to the charging corona charger used in the normal image forming process and by shielding a part of the corona → -discharge area. 5 iIT described in claim 1! i 1J4' concentration fail I+li1 method.