JPH0284677A - Toner concentration controller for copying machine - Google Patents

Abstract

PURPOSE:To always obtain stable image quality by controlling the replenishing quantity of toner which is replenished to a developing device according to the adhering quantity of toner which is detected by a toner detection means. CONSTITUTION:At the time of exchanging developer, the adhering quantity of the toner of an untransferred pattern image which adheres to the surface of a photosensitive body 1 is detected by the toner detection means 16 and a detection level is measured by a toner replenishing quantity control means 20 based on the detected adhering quantity of the toner. According to the detection level, toner replenishment rate is selected so that the replenishing quantity of the toner which is replenished to the developing device 6 may be an optimum value. Thus, the density of an image formed on a transfer paper can be kept uniform and the stable image quality can be always obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a toner concentration control device for a copying machine having a toner concentration control mechanism.

2. Description of the Related Art A conventional copying machine will be explained with reference to FIG. When the photoreceptor 1 begins to rotate in the direction of the arrow, the charger 2 is turned on at a certain timing, and the surface of the photoreceptor 1 is uniformly charged. The charged surface of the photoreceptor 1 is exposed to light 3 emitted from a light source (not shown) to form an electrostatic latent image, and excess charges on other unexposed areas are erased by a static eliminator 4. . Thereafter, the electrostatic latent image is sequentially developed by a color IIA imager 5 and a black developer 6, thereby forming a toner image 7 on the surface of the photoreceptor 1. This toner image 7 is transferred to a transfer paper 9 inserted by a registration roller 8 as an electric charge having a polarity opposite to that of the toner image 7.
Transcribed by. The transferred transfer paper 9 is separated from the photoreceptor 1 by a separator 11 and guided to a fixing section 12.

On the other hand, the toner 13 remaining on the surface of the photoreceptor 1 is removed by the cleaning device 14, so that the surface of the photoreceptor 1 is cleaned and returned to its original position.

In this case, a P sensor 15 is provided between the transfer device 10 and the cleaning device 14, and the P sensor 15 detects the amount of light reflected from the toner image 7 formed on the surface of the photoreceptor 1. Depending on the color developer 5 or black developer 6
The toner density is controlled.

Problems to be Solved by the Invention As a method for replacing the developer (toner) in the conventional apparatus as described above, in addition to a method in which the user replenishes the developer (toner) using a toner cartridge (not shown), a service person directly replaces the toner 13. There is a method of replenishing the inside of the color developer, but in this case, after replenishing the color developer, the service person
Initial settings are made by selecting the toner replenishment rate to be supplied to the black developing device 6 using a dip switch or the like. Generally, such toner replenishment rates are 45%, 30%, and 15%.
It is divided into stages, and normally, the toner replenishment rate is initially set to 30%. In such a state, the amount of deviation between the value measured by the P sensor 15 and the reference value is compared, and depending on the amount of deviation, 1/4.1/2.1/1 of the 30% replenishment rate is determined. Adjustments are made by changing the amount of supply.

However, there is no reason to initially set the toner replenishment rate to 30% in advance, and there are also variations in the surface potential when creating the toner image 7 and variations in the gap between the photoreceptor 1 and the black developer 6. The toner density value may change depending on the developing capacity of the color developing device 5 or the black developing device 6. For example, if a large amount of toner 13 is replenished at once under conditions where the toner density is currently controlled to be high, it may cause background smudges, or if the toner density is controlled to be low. Under such conditions, such scumming is not observed, but there is a problem in that the image density on the transfer paper 9 tends to be insufficient.

This type of problem can hardly occur if the toner replenishment rate is set to the optimum value in advance when replacing the developer. However, in conventional devices, the toner replenishment rate is not set to the optimum value in advance. There is no adjustment method to set it to . In other words, the selection position of the toner replenishment rate when replenishing toner is normally set to 30% by the service personnel, and it is not set to a position that takes into account the subsequent usage conditions, so the toner concentration As a result, the above-mentioned problems cannot be eliminated.

Means for Solving the Problems In order to solve the above problems, the present invention forms an untransferred pattern on the surface of the photoreceptor when replacing the developer, and removes the formed untransferred pattern image. A toner detection means for detecting the amount of toner adhesion is provided, and a toner replenishment amount control means is provided for controlling the amount of toner replenishment to be supplied to the developing device according to the amount of toner adhesion detected by the toner detection means.

Effect therefore! ! When replacing the developer, the toner detection means detects the toner adhesion amount of the untransferred pattern image adhering to the surface of the photoreceptor, and the toner replenishment amount control means detects the detected toner adhesion amount based on the detected toner adhesion amount. It is possible to measure the level and select the toner replenishment rate so that the amount of toner replenished to the developing device is the optimal value according to the detected level, and thereby the image created on the transfer paper Since the density can be kept uniform, stable image quality can always be obtained.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 to 3. Note that since the overall configuration of the copying machine has been described in the related art, the description thereof will be omitted, and only the toner density control device according to the present invention will be described here. Also, the same reference numerals are used for the same parts as in the conventional device.

A P sensor 16 as a toner detection means is disposed between a transfer device 10 and a cleaning device 14 provided around the photoreceptor 1 to detect the amount of toner adhering to the surface of the photoreceptor 1. has been done. Further, this P sensor 16 is connected to a detection level measuring device 17, this detection level measuring device 17 is connected to a toner supply vehicle selection device 18, and further, this toner supply vehicle selection device 18 is connected to a toner supply clutch 19. ing. The detection level measuring device 17, the toner replenishment vehicle selection device 18, and the toner replenishment clutch 19 constitute a toner replenishment amount control means 20. The toner replenishment clutch 19 is
It is connected to the toner replenishing roller 21 in the black developing device 6.

In such a configuration, how the toner 13 adhering to the surface of the photoreceptor 1 is controlled will be explained. It is now assumed that the developer toner 13 is due for replacement. At this time, an untransferred pattern (not shown) is formed on the photoreceptor 1, and the amount of toner adhering to the formed untransferred pattern image is detected by the P sensor 16. Thereafter, the signal detected by this P sensor 16 is sent to a detection level measuring device 17, where the detection level (inching value) is measured. Toner replenishment rate selection device according to the measured detection level! ! 18, the optimum value of the toner replenishment rate is selected. Thereafter, the selected signal is sent to the toner replenishment clutch 19 to drive the toner replenishment roller 21 inside the black developing device 6, thereby replenishing the amount of toner replenished inside the black developing device 6. can be adjusted to the optimal value. By adjusting the toner density to the optimum value in advance when replenishing the toner 13 in this way, it is possible to maintain a uniform toner density adhering to the surface of the photoreceptor l, thereby constantly stabilizing the image quality on the transfer paper 9. It can be kept in the same condition.

Next, the relationship between the toner replenishment rate and the inching value will be explained based on FIG. 2. Now, if the inching value measured by the detection level measuring device 17 is small (less than 10%), the toner density will be controlled to be low because the developing ability during toner image creation is large. As a result, the amount of charge of the developer (not shown) becomes higher, and the charged toner 13 that is replenished also becomes more charged, so the electrostatic force between the carrier (not shown) and the toner 13 becomes stronger, and the image density tends to decrease. becomes. In such a case, set the toner replenishment rate to level A (45%), which is higher than the normal state (level B).
By setting the image density to , the image density can always be kept stable.

Further, when the 1 inching value is large (20% or more), the developing ability during toner image formation is small, so the toner density is controlled to be high. As a result, the amount of charge on the developer (not shown) becomes low, and the toner 13 replenished accordingly.
Also, since the rise of charging is delayed, a large amount of toner 1 is
When 3 is replenished, it tends to become dirty. In such cases.

Set the toner replenishment rate to level C (15%), which is lower than the normal state.
) to create conditions that make it easy for the toner 13 to be replenished to stand up, it is possible to prevent background smearing and keep the image density stable at all times.

Here, the 1 inching value will be explained.

When replenishing the toner 13, a copying operation for 20 copies is made to create a toner image 7 each time, and all other parts are neutralized.The P sensor measures the toner adhesion amount of the toner image 7 created each time. At step 16, the value is read and set as VP, while the amount of toner adhesion on the portion where the charge has been removed is also read and the value is set as Vg. After completing 20 measurements in this way, 1 measurement is made from the 11th measurement for VP and Vg.
The average values V sp and V sg up to the eighth time were determined, and the value of (Vsρ/Vsg)X100 was thereby determined as the inching value. Note that FIG. 3 represents the above-mentioned contents as a flowchart.

Effects of the Invention The present invention forms an untransferred pattern on the surface of a photoconductor when replacing the developer, and includes a toner detection means for detecting the amount of toner attached to the formed untransferred pattern image. Since the toner replenishment amount control means is provided to control the amount of toner replenished to the developing device according to the amount of toner adhering to the developing device, when the developer is replaced, the untransferred pattern image adhering to the surface of the photoreceptor is The toner adhesion amount is detected by the toner detection means, the detection level is measured by the toner replenishment amount control means based on the detected toner adhesion amount, and the toner is replenished to the developing device according to the detection level. It is now possible to select the toner replenishment rate so that the toner replenishment amount is at the optimum value, and this allows the density of the image created on the transfer paper to be kept uniform, making it possible to always obtain stable image quality. be.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing one embodiment of the present invention, Fig. 2 is a graph showing the relationship between toner replenishment rate and inching value, Fig. 3 is a flowchart for determining the inching value, and Fig. 4 is a conventional method. 1 is a schematic longitudinal sectional side view showing the overall configuration of a copying machine. DESCRIPTION OF SYMBOLS 1... Photoreceptor, 2... Charger, 5.6... Developing device, 7... Toner image, 10... Transfer device, 16... Toner detection means, 20... Toner Replenishment amount control means

Claims (1)

[Claims] The surface of the photoreceptor charged by a charger is exposed to light to form an electrostatic latent image, this electrostatic latent image is developed by a developer to form a toner image, and the formed toner image is transferred by a transfer device. In a copying machine that forms an image by transferring it to transfer paper, an untransferred pattern is formed on the surface of the photoreceptor when the developer is replaced, and toner detection detects the amount of toner attached to the formed untransferred pattern image. Toner density control for a copying machine, characterized in that a toner replenishment amount control means is provided, and a toner replenishment amount control means is provided for controlling an amount of toner replenishment to be replenished to the developing device according to the toner adhesion amount detected by the toner detection means. Device.