JPS60131575A - Adjusting method of toner density - Google Patents

Abstract

PURPOSE:To reproduce a recording image with a high gradient stably by AC bias development which uses a compounded developer by developing a reference latent image on an image carrier with a reference AC bias and detecting toner density from its development characteristics. CONSTITUTION:The reference latent image is formed by electrostatic charging and exposure and the position where said reference latent image reaches a development area A is detected from the number of encoder pulses of an encoder which rotates together with a photosensitive drum 2 to develop the reference latent image with a reference oscillation bias. The developed reference latent image is detected by an optical means 14, whose detection information is compared with the contents of the memory in a CPU to detect or decide on toner density. Further, the relation between the recording image density and toner density in the presence of the oscillation bias is obtained by experiment.

Description

[Detailed description of the invention] [Industrial application details] □ The present invention uses powder □ toner and ♀ sand □ □ 22
Photocopying the current image using a developing agent with 5 electrons per line
With VIP electronic recording equipment and recording equipment that uses magnetic fusion.

This is an improvement to the concentration adjustment method for adjusting the density of the developer.
Conventional technology ゛゛゛With an electrostatic recording device, the reproduced image has a high color density in the first part, and the image part becomes capricious, resulting in a gradation that is faithful to the original. It is required to be rich. In order to satisfy this core requirement, it is first determined that the mixing ratio of powder toner and carrier is appropriate.

The toner concentration detection means of the two-component developer is □ and 1.
・, 4 1 ・ - There are many □ proposals such as how to use the electrical characteristics of the constitution □ 4
At 8'i (□・ru:'εa-゛-□°-sensing quasi-latent image)Y
: The inverse of the reference image developed by a photocoupler consisting of a light-emitting element and a light-receiving element formed on the body and developed.
There is a known method to keep the density constant and detect the toner density.
c(, machine゛ □ This method is easy to test, inexpensive, and undetectable. 51!
! The present inventors have invented a developing method in which two-component image quality is used and AC bias is used, and have proposed such a developing method. When developing the above-mentioned reference latent image under AC bias, normal AC bias development faithfully reproduces changes in the developer, making it suitable for image adjustment, but it is suitable for use in toner concentration detection. is not suitable. However, under certain bias conditions, there is a region in which the developability is less dependent on changes in the developer. By using this region of small magnetization of the developer, it is possible to detect the toner concentration.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner density adjustment method applicable to an electrostatic recording device that uses a two-component developer and performs development using an AC bias.

[Structure of the invention]

The present invention is an attempt to achieve the above object, and is characterized in that a reference latent image formed on an image carrier is developed under a reference AC bias, and the toner density is detected based on the development characteristics. A method for adjusting toner density is provided.

〔Example〕

FIG. 1 is a schematic configuration diagram showing an example of a developing device implementing the method of the present invention, and FIG. 2 is a graph showing the relationship between electrostatic image potential and recorded image density when the amplitude of the oscillating electric field is changed. .

In FIG. 1, -M rotates in the direction of the arrow, and a known charging and exposure device (not shown) or an electrostatic latent image forming device (not shown) using a multi-stice electrode or an ion control electrode is applied to the surface.
Therefore, a drum-shaped image carrier having an electrophotographic photoreceptor layer or a dielectric layer on which an electrostatic image is formed, 2 a developing sleeve made of a non-magnetic material such as aluminum, and 3 inside the developing sleeve 2. The developing sleeve 2 and the magnet 3 constitute a developer transport carrier. The developing sleeve 2 and the magnet body 3 can rotate relative to each other, and the figure shows that the developing sleeve 2 rotates to the left and the magnet body 3 rotates to the right. Further, the N and 8 magnetic poles of the magnet body 3 are normally magnetized to a magnetic flux density of 500 to 1500 Gauss, and the magnetic force causes the surface of the developing sleeve 2 to be charged with a developer consisting of toner particles and magnetic carrier particles that can be charged by friction. The so-called magnetic film 2. to form and do shi. The toner particles in the developer have a weight average particle size of 3 to 3.
0μm.

Preferably, the magnetic carrier particles have a weight average particle size of 5 to 50 μm (determined in m using Coulter Counter (Coulter 11) 1.t Municon Alfa (manufactured by Bauschlot 5)), and even magnetic carrier particles. is VCwI in insulating resin
Disperses sexual particles! It is preferable to have the following. Also 1,
The resistivity of the carrier particles is 10Ω or more, especially [10Ω1
As mentioned above, it is preferable to form the indispensable magnetic particles in 5. This resistivity is determined by placing the particles, vo, in a container with a cross-sectional area of 50 cI and tapping, then applying a load of 1 klF/cII on the tied particles, and applying 7000 V/cI between the load and the bottom electrode. This value is obtained by applying a voltage that generates a cIL electric field or by reading a current value, and if the resistivity is low, the bias voltage on the developer transport carrier,! Charge is injected into the carrier particles by the applied charge, making it easier for the carrier particles to adhere to the surface of the carrier, or for breakdown of the bias voltage to occur more easily. The magnetic brush moves in the same direction as the rotation of the developing sleeve 20 by the rotation of the developing sleeve 2 and the magnet 3, and is conveyed to the developing area A where the surface of the developing sleeve 2 faces the image carrier 1ζ.

4 is a layer thickness regulating blade made of magnetic or non-magnetic material that regulates the height and amount of the magnetic pusher on the surface of the developing cage 12; between the surfaces of the image carrier 1 and the developing sleeve 2; If the layer thickness is greater than the thickness of the brush, that is, the brush does not rub the surface of the image carrier 1, and the toner particles fly from the magnetic brush and adhere to the electrostatic image on the image carrier 1, so-called non-contact. It is preferable to set the distance at an appropriate distance for development. The surface gap between the image carrier 1 and the developing sleeve 2 is set to 0.3 to 2.
The layer thickness of the magnetic brush is 0.1 to 1.5 m%, and the magnetic brush and the surface of the image carrier 1 are placed as close as possible.
! ! ! It is preferable to set it so that a gap of 0.01 to 1 mI is created. By providing a short period of time between 5 and 9, the image quality can be greatly changed during contact, and the accuracy of detecting changes in developability can be improved. Furthermore, due to changes in the developing bias during development, there is a region in which the developability does not change much even if the developer changes under certain conditions, and this region is used for toner concentration control.

5 is a cleaning blade that removes the magnetic brush that has passed through the developing area A from above the developing sleeve 2; 6 is a developer reservoir;
7 is a stirring screen that stirs the developer pool in developer reservoir 6 to uniformly mix toner particles and carrier particles; 8 is a toner hopper for replenishing toner particles T; 9 is a toner particle in developer reservoir 6; T'? ! - A toner supply roller having four parts on the surface for dropping; 10 is a vibrating power source □ which applies a voltage having a vibrating component to the developing sleeve 2 through a protective resistor 11 to form a ℃ developing area AIC vibrating electric field; The oscillating power supply 10 outputs a voltage with a different oscillating waveform by changing one or more of the amplitude of the AC voltage or pulsed voltage, the bias based on the DC voltage component, the selected time and frequency by time-selective waveform conversion, etc. By changing the oscillating waveform of the oscillating electric field formed in the developing area A, the recorded image density can be adjusted. .

FIG. 2(1) shows the recorded image density when the vibrating power supply 10 of FIG. 1 applies an AC voltage of various amplitudes at 3° to a DC bias voltage of 1100V. Here, the curve shown by CA is the average charge amount of the two-component developer, and the curve shown by C-B is the average charge amount of the two-component developer of 10 μC/11.

In addition, Fig. 2 (b) shows that the vibration power source IO in Fig. 1 is 3 KHz.
.

The relationship between the toner density and the recorded image density under the developing bias condition of applying a DC bias voltage of 7100V to an AC voltage of 3KV is as follows: The average charge amount of the two-component developer is 9μC/11
(C-A) and 10 μC/11 (C-B).

The layer of the image carrier 1 on which an electrostatic image is formed is composed of a charge generation layer and a charge transport layer made of an organic photoconductor OPC, and the reference latent image is charged to -500VK.

Its surface velocity in the direction of the arrow is 120 myx/Sec,
The gap between the image carrier 1 and the developing sleeve 20, that is, the gap between the developing area A, is 700 μm, and the outer diameter is 30. The rotation speed of the developing sleeve 2 in the direction of the arrow is 65r, p, m, and the gap between the layer thickness regulating blade 4 made of non-magnetic material and the developing sleeve 2 is 300/m.
jm, N with a magnetic flux density of 900 Gauss, the number of rotations in the direction of the arrow of the magnet 3 having 8 magnetic poles at equal intervals γ00r, p,
The developer has a weight average particle diameter of about (1) μm and a resistivity of about 1×10 g when magnetic powder is dispersed in the resin.

By using a two-component developer consisting of an insulating magnetic carrier and an insulating non-magnetic toner with a weight average particle size of 14 μm, development can be performed under the condition that the layer thickness of the magnetic brush formed on the developing sleeve 2 is approximately 500 μm. The results are shown below. Note that the recording me density on the vertical axis indicates the developed toner gj1 as the first
This is the image density of the recording paper obtained by pressure-transferring the recording paper using a transfer device (not shown) and fixing the transferred toner image □ using a fixing device, which corresponds to the development density.
Vae of each concentration curve is the output AC voltage of the vibration power supply 10,
The potential of the background portion of the electrostatic image, that is, the non-image portion, was 15 ov.

As is clear from FIG. 2(a), even if the developer fluctuates, the density of the recorded image can be kept constant by changing the amplitude of the oscillating electric field formed in the developing area.
There is a region showing C1l concentration.

In this high electric field region, the development density change does not depend on the developer variation, but depends on the toner density as shown in FIG. 2(b). ' As for the oscillating electric field, the effective value of the AC voltage component is 200 to 5.
By applying an oscillating voltage of ooo v, an electric field strength of 300 to 3000 v/m in effective value is preferably generated.

The present invention is not limited to the example of changing the amplitude in FIG.
Vibration waveform time selection conversion as proposed in s58-145031 eel (for example, changing the duty ratio to 4 etc.) [
4 can be something that can be changed or something that can be given, such as a frequency. Wet Jin Kuwa 1,,,. When changing the frequency, since the developing density and the recording density decrease as the frequency increases, the toner density can be adjusted by changing the frequency within that range, although it depends on the voltage. The preferred frequency range is 0.3-5 KHz.

'About an electrostatic recording device having such a developing device-C
, the sequence of the present invention will be described. First, a constant reference latent image is formed by 1° by charging φ exposure.

This base latent image is usually formed by forming the back surface in white, pasting a reference mark of white, gray, black, etc. near the center and exposing this part to light.

The point at which the reference latent image formed on the image carrier reaches the development area AtC is detected by the number of encoder pulses rotating together with the photoreceptor drum, and the latent image is developed by the reference vibration bias. . This reference vibration bias may be a constant value, but may be changed by a 5 & lc fixed program as described later. The voltage applied to the developing device is such that during non-development, a floating bias or a DC bias that prevents toner adhesion is applied.

The reference latent image developed under the reference vibration bias can be detected by optical means that measures the reflection density using a combination of a light-emitting element and a light-receiving element.

This detected information may be, for example, a change in photoreceptor potential.

Variations occur due to changes in illumination lamps, developer, temperature, humidity, etc., but in the present invention, development is performed under a standard vibration bias that is free from variations due to developer changes.

This detected information is compared with a memory stored in the CPU in advance, and the toner density is detected or determined. The relationship between the recorded image density and the toner density under vibration bias is experimentally established as shown in FIG. 2(b). Note that the information obtained at this time and the information obtained by the temperature/humidity sensor can also be used as information for bias adjustment when developing the latent image of the document. Furthermore, the present invention is applicable to Japanese Patent Application No. 184381/1984, filed earlier by the applicant.
No. 8-183152, No. 58-187000, No. 58
It is also possible to apply the present invention to the method described in No. 187001, in which a color image is formed by repeatedly developing a plurality of image carriers and overlapping a plurality of toners.

(Example 1) A black marker plate was provided on the back side of the document table as a reference marker for forming a reference latent image. The reference latent image potential above the photoconductor fly caused by this is -400 current voltage 3 KHz, 3.5 Kv, DC bias voltage -1
Development is performed under AC bias conditions of 00V, and the reflection density of this toner image is detected by the sensor 14 shown in Fig. 1, and this detection output is set to a predetermined value set in the CPU. By comparing the toner supply roller (
9) is used to determine whether or not toner should be supplied.

(Embodiment 2)' - □As in Embodiment 1, a reference latent image of a black and white reference plate is created on the photoreceptor. Just now - 1 to the reference latent image on the light body
7, development is performed in the development area using a bias voltage set in advance in a program. That is, the oscillating power supply 10 of FIG. 1 was used for development with a fixed current bias voltage 'VC of 3 KHz of 1100 V' and an alternating current amplitude variation of θ to 4 KV. The reflection density of the toner image corresponding to this and plum black - 1v
! Jme21-C14mo was detected. This detection results in a high cum concentration!゛□Detection output of black background is C
The toner concentration is adjusted by rotating the toner supply roller by comparing the pH with a predetermined value stored in the PH.

On the other hand, the image density corresponding to each bias condition is A/D converted by the A/D converter 13, inputted to the CPU, and compared with desired image density information stored in advance. By using the bias conditions (amplitude of AC component and DC component) obtained from the black background and white background information 1j, it is possible to prevent fog and obtain an image with excellent gradation. It will be done.

[□Effect of invention]

'According to the present invention, it is possible to easily increase the toner density v! using a relatively simple device using a developing method KN under AC bias using a composite developer. The effect is that it is possible to stably reproduce recordings with excellent gradation by adjusting M.
Moreover, it is 1w because feedback is given on developability! It can be said that the recorded image density can be adjusted with excellent accuracy and reproducibility, and very good results can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a developing device that performs a non-explosion process.
In the configuration diagram, FIG. 2 (4) shows the relationship between the recorded image density when the amplitude of the oscillating electric field is changed, and FIG. 2 1bl shows the relationship between the toner density and the recorded image density. DESCRIPTION OF SYMBOLS 1... Image carrier-holder 2... Developing sleeve 3... Magnet body 4... Layer thickness regulation blade 5... Cleaning blade 6... Developer reservoir 7... Stirring screen 8 ... Toner hopper 9 ... Toner supply roller 10 ... Vibration power supply 11 ... Protective resistor 12 ... D/A converter
13... A/D converter 14... Photo sensor representative Kuwahara - Figure 1

Claims (1)

[Claims] (1) A toner density adjustment method, which is characterized in that a reference latent image formed on a supporter is developed under a reference vibration bias, and the toner density is detected based on the development characteristics.゛ □□ □ (2) The toner concentration adjusting method according to claim 1, wherein the development is performed while maintaining a gap between the image carrier and the developer layer. ′