JP3413282B2 - Toner supply control method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer,
The present invention relates to a toner supply control method applied to a developing device of an image forming apparatus using an electrophotographic method such as a facsimile. 2. Description of the Related Art A toner replenishment control method for a developing device using a two-component developer that makes toner adhere to an electrostatic latent image formed in units of dots in accordance with recording information to make the image visible is provided. ,
The image forming apparatus has a developer concentration detecting means for detecting a developer concentration in the developing device, and a dot counting means for counting the number of dots to which toner adheres. The detection output of the developer concentration detecting means (toner density sensor) is V _T , When the reference value is V _REF and the toner consumption amount obtained from the area ratio data, which is the counting result of the dot counting means, is X, the toner replenishment amount = X × F (V _REF −V _T ) (where F (V _REF) −V _T ) is the output V of the toner density sensor
_The function is set in advance from the difference between _T and the reference value _VREF . )
There is known a toner supply method for determining a toner supply amount. A conventional toner replenishing method will be described with reference to FIGS. Referring to FIG. 1 illustrating the outline of the main part of the electrophotographic apparatus, when the image forming operation is started, first, the photoconductor 1 starts rotating in the direction of arrow A in the figure. Next, the charging device 2 uniformly charges the photoconductor, and the writing data is exposed in the form of dots. [0004] In parallel with this, dot data weighted by the writing light amount is converted into a predetermined image unit, for example, copy 1.
The integration is performed for each sheet (step [1]), and the value is converted into the toner consumption X (step [2]). By this exposure, a charge image is formed on the photoconductor, and this charge image is developed by the developing device 3 (step [3]). The inside of the developing device 3 is as shown in FIG. 6, and the developer is conveyed as indicated by a dotted arrow, and the charge image on the photoconductor is developed. The density of the developer 7 is detected by a toner density sensor (hereinafter, referred to as a T sensor) 8 (step [4]). From the detection output V _T of the T sensor as shown in FIG. 4, the difference [Delta] V between the reference value V _REF is determined (step [5]), the value F ([Delta] V) by a function or a table, as shown in FIG. 7 Desired. This value F (ΔV) has a value of 0.0 to 3.1 in this example. [0006] This value corresponds to the toner consumption X obtained previously.
To determine the toner supply amount (step [6]). Then, a replenishment time t corresponding to the toner replenishment amount is set.
The supply device is driven to supply toner (step [7]). Specifically, the supply roller 9 shown in FIG. 6 rotates, and the toner 10 is supplied. The developed toner image is transferred to paper by a transfer device 4 shown in FIG. 5, and transfer residual toner is removed from the photoreceptor 1 by a cleaning device 5. Thereafter, the photosensitive member 1 is neutralized by the neutralization lamp 6, and the next image is formed. When the image forming operation is completed, first, as shown in FIGS. 4 and 5, it is determined whether or not it is the detection timing of the P sensor 12 for detecting the density of the reference pattern [8]. Detection by P sensor is 10 to 200
This is performed every time a predetermined number of sheets are formed. If it is the P sensor detection timing, the output of the charging device 2 and the bias voltage applied to the developing roller 11 of the developing device 3 are changed to those for the P sensor (step [9]), and the write data is the P sensor pattern data. used. Thus, the reference pattern is developed on the photoconductor. Next, the transfer device is released and the P sensor 1
2 Concentration of P sensor pattern is detected, the output ratio V _SP / V _SG of the ground is calculated (step [10]).
The output ratio V _SP / V _SG is compared with the reference values η and η ′ (steps [11] and [12]), and the reference value V _REF of the toner density sensor is changed according to the result to obtain V _REF + C or V _{REF. REF} + C '(steps [13], [1
4)), the image forming operation ends. Japanese Patent Application Laid-Open Nos. 61-29871 and 62-52 disclose similar control.
No. 78 and Japanese Patent Application Laid-Open No. 63-144377 disclose techniques. All of the techniques disclosed in these publications determine the toner replenishment amount by predicting the toner consumption from the black area of the image by using the fact that the black area of the image is known with the digitization of the electrophotographic apparatus. That is. In the above-described toner supply control method, when a printout with a large black area is performed, the toner supply amount can be quickly increased and the toner density can be adjusted to the reference value. If there is not much deviation,
While stable control with little fluctuation in toner density is possible,
Documents that are close to blank paper (documents whose image area is close to 0) when the toner density is deviated from the reference value and becomes thinner
When an image close to a blank sheet (an image having an image area close to 0) is printed out by copying or the like, the toner replenishment becomes zero despite the desire to replenish the toner immediately. At first glance, it is considered that there is no problem. However, in actuality, when the toner density is greatly deviated from the target (for example, immediately after the toner tank is emptied and toner is replenished, the environment changes and the P sensor (For example, when the reference value is changed), there is a problem that an appropriate image density cannot be obtained for the next image because toner is not supplied in the above-described control. An object of the present invention is to provide a toner replenishment control method which can always obtain an appropriate image density. [0014] In order to achieve the above object, the present invention is configured as follows. (1). What is claimed is: 1. A toner supply control method for a developing device, in which toner is attached to an electrostatic latent image formed in units of dots in accordance with recording information to visualize the toner, the developer concentration detecting unit detecting a developer concentration in the developing device. And a dot counting means for counting the number of dots to which toner adheres, wherein the detection output of the developer concentration detection means is V _T , the reference value is V _REF ,
X is the amount of toner consumption obtained from the counting result of the dot counting means.
Where, toner supply amount = X × F (V _REF −V _T ) (where F
(V _REF −V _T ) is a preset function including a zero value . In the toner replenishment control method for determining the toner replenishment amount, when the toner consumption amount X is equal to or less than a predetermined value, the toner consumption amount X is replaced with a separately set minimum toner amount.
The toner supply amount is determined by using a predetermined value M that can ensure the supply (claim 1). According to the first aspect of the present invention, even if the detected area ratio is 0, a predetermined value other than 0 is input as the lower limit to calculate the toner supply amount. Embodiments (1). FIG. 1 shows an embodiment of the present invention. In this example, the contents of step [2] in the flowchart shown in FIG. 4 are replaced with the flowchart shown in FIG. In the flowchart shown in FIG. 1, the integrated value of the dot data calculated in step [1] is compared with a predetermined value M in step [2-1]. If it is larger than the predetermined value M, the process proceeds to step [2-3], where the integrated data is converted into the toner consumption X, and the process proceeds to step [6]. If it is determined in step [2-1] that the value is smaller than the predetermined value M, the process proceeds to step [2-2], the integrated data is set to M, and the process proceeds to the next step [2-3]. The integrated data M is converted into the toner consumption X and the step [6] is performed.
Proceed to. As described above, as the predetermined value to be compared with the integrated value of the write data, the value of M, which is the minimum value other than 0 that can ensure the minimum toner supply, is determined. In the case of the integrated value, the toner is supplied using M as the integrated value. Here, the size of M is set as a value that can achieve toner supply such that a 6% black image can be formed in A4 size. In this way, even when a document close to a blank paper comes, toner supply is minimized, and a proper image is always formed. (2). Reference Example 1 FIG. 2 shows a reference example. In this example, the content of step [6] in the flowchart shown in FIG. 4 is replaced with the flowchart shown in FIG. In the flowchart shown in FIG. 2, the value V _REF calculated in step [5]
-V _T = [Delta] V is in step [6-1], a predetermined value (-
0.1). If ΔV is larger than (−0.1), the process proceeds to step [6-2] having the same contents as step [6] in FIG. If the value ΔV is smaller than the value (−0.1),
In step [6-3], the toner replenishment time t is determined by adding a term including a constant K irrelevant to the dot count result and a term ΔV × K to the original X × F (ΔV). Here, the value (−0.1) is determined according to each machine as a value when the toner shortage is eliminated by adding the value of the term ΔV × K. In this embodiment, when the deviation ΔV of the toner density from the reference value is out of the predetermined range (−0.1),
The amount to be replenished is determined from the difference (ΔV) between the output of the toner density sensor and the reference value irrespective of the writing data, and is added to the toner replenishment amount. In this embodiment, the predetermined value (-0.1) and the value of K are different depending on the characteristics of each machine, and are values that can provide a toner replenishment amount such that the toner concentration does not deviate from a target level. Is set. (3). Reference Example 2 FIG. 3 shows a reference example. In this example, the content of step [6] in the flowchart shown in FIG. 4 is replaced with the flowchart shown in FIG. In the flowchart shown in FIG. 3, the value V _REF calculated in step [5]
-V _T = [Delta] V is in step [6-1], a predetermined value (-
0.1). If ΔV is larger than (−0.1), the process proceeds to step [6-4] having the same contents as step [6] in FIG. If the value ΔV is smaller than the value (−0.1),
In step [6-5], the toner supply time t is set to the predetermined value L.
Then, the process proceeds to the next step [7], and a fixed amount of toner is supplied by this time L regardless of the dot count result. If the value ΔV is larger than the value (−0.1), normal toner replenishment is performed in step [6-4]. The basis for determining the value (−0.1) and the time L is based on the example of the above (2). According to the present invention, even when the black area of an image is very small and toner supply is not normally performed, if the toner density in the developing device is low, a certain amount of toner can be obtained. Since replenishment is ensured, an image having a stable density can always be output.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart according to an embodiment of the present invention. FIG. 2 is a flowchart according to a reference example. FIG. 3 is a flowchart according to a reference example. FIG. 4 is a flowchart illustrating a conventional toner supply control method. FIG. 5 is an explanatory view of a main part of an image forming apparatus suitable for carrying out the present invention. FIG. 6 is a diagram illustrating a configuration of a developing device suitable for implementing the present invention. FIG. 7 is a graph illustrating data for obtaining FΔV from ΔV. [Explanation of Signs] M Predetermined value X Toner consumption

Claims (1)

(1) A toner replenishment control method for a developing device, in which toner is adhered to an electrostatic latent image formed in units of dots in accordance with recording information to visualize the image, the method comprising: The apparatus has a developer concentration detecting means for detecting the developer concentration in the apparatus, and a dot counting means for counting the number of dots to which toner adheres. The detection output of the developer concentration detecting means is VT, the reference value is VREF, and the dot is a dot. When the toner consumption amount obtained from the counting result of the counting means is X, the toner supply amount = X × F (V _REF −V _T ) (where F
(V _REF −V _T ) is a preset function including a zero value . In the toner replenishment control method for determining the toner replenishment amount, if the toner consumption amount X is equal to or less than a predetermined value, a separately set minimum toner replenishment amount may be used instead of the toner consumption amount X.
A toner supply control method, wherein a toner supply amount is determined using a predetermined value M that can be secured .