JPS59124358A - Controlling method of toner density in electrophotographic device - Google Patents

Abstract

PURPOSE:To maintain a specified image density constant by setting upper and lower limits to the toner density of a developer and replenishing the toner in such a way that the actual condition of the toner density is made to conform to the set upper/lower limits. CONSTITUTION:When a main switch is turned on, a sequence controller operates and investigates the bias voltage of a developing unit and the heating temp. of a photosensitive drum D. When the controller confirms that said voltage and temp. comply with set values, a developing sleeve turns to supply the developer in a developing tank T to a toner density detector 1, the value thereof is then inputted to a toner density range setter 2. When the density signal is below the lower limit value, an L signal is outputted from a detecting circuit 2c for the lower limit of the toner density and operates a driving circuit 7 for a toner replenishing member to replenish the toner until an H signal is outputted from the circuit 2c, thereby the toner is replenished until the toner density conforms to the upper/lower limits. A copying operation is started in the stage when such preparation is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling toner density in an electrophotographic apparatus.

Conventionally, toner density control in electrophotographic devices that use a two-component developer consisting of toner and carrier uses a toner density detector such as an F sensor that directly detects the toner density of the developer. A method of operating a toner replenishing member depending on the toner concentration, and an image density detector such as a P sensor that optically detects the density of a standard pattern imaged on the photoreceptor drum 1 immediately before each copying operation are used. , a method was adopted in which the toner replenishing member was operated so that the image density was set (177). However, the former method could not compensate for changes in image density due to deterioration of the exposure system or charging system; In addition, Gonagi's method does not require a scale that places a burden on the cleaning unit or increases toner consumption;
・There was a problem that the density was likely to be too high or too low, and if the line image became too thick, the carrier would appear as 4=J.

In view of these problems, the present invention provides not only a scale that can produce copies with high image quality, but also a device for controlling the concentration of 1. The present invention will be described below with reference to embodiments.

The figure is a long diagram showing an example of the device used in the present invention, and the reference numeral l in the figure is a concentration detector such as an F sensor for detecting the toner concentration of the developer. It is provided on the separator S that comes into contact with the developing sleeve of the developing tank T, and the signal from this is output to the developer concentration range setting device 2. This developer concentration range setting device 2 includes an averaging circuit 2a that averages the signals from the toner concentration detector over the period of one copy and one operation, and an averaging circuit 2a that averages the signals from the toner concentration detector l over the period of one copy and one operation, and an averaging circuit 2a that averages the signals from the toner concentration detector l over the period of one copy and one operation, and an averaging circuit 2a that averages the signals from the toner concentration detector l over the period of one copy and one operation. When it exceeds the H signal, this is the F signal.
The toner upper limit concentration detection circuit 2b outputs an L signal when the concentration exceeds the lower limit, for example, 2wt%, and the lower limit toner concentration detection circuit 2c outputs an L signal when the concentration exceeds the lower limit, for example, 2wt%. )1 limit detection circuit 2
The signal from the toner upper limit concentration detection circuit 2c is input to one terminal of the gates 1 and 3 which are NAND circuits, and the signal from the toner upper limit concentration detection circuit 2c is output to the toner replenishing member drive circuit 7.

Reference numeral 4 denotes an image density detector such as a P sensor disposed close to the photosensitive drum D, which detects the image density by a signal from a sequence controller that outputs a predetermined number of copies, for example, every 20 copies.
It is configured to detect the optical density of a standard pattern imaged on the photoreceptor drum D. Reference numeral 5 denotes an image density setting device which sets a zero signal when the signal output from the image density detector 4 is a predetermined density, for example II) -1, 12, and an H signal when it exceeds this. It is configured to output an L signal when the Reference numeral 6 denotes an I-su replenishment amount adjuster, which adjusts the amount of toner to be replenished at one time according to the signal from the paper size detector 8 that detects the size of the copy paper, depending on the operating time of the toner replenishment member drive circuit 7, e.g. , 2.4 seconds for 20 sheets of A4 size paper, and 1.2 seconds for 20 sheets of A5 size paper. L from the image density setter 5 inputted via the gate 3
The device is configured to be activated by a signal. 9 is )・
For the concentration alarm, connect one terminal of each
A signal from the image density setting device 5 is input through the terminals 9a and 9b, and the toner limit detection circuit 2 is input to each of the other terminals.
b and cables 1, 9c, and 9d which are manually operated by the signal from the lower limit concentration detection circuit 2C;
The system is configured to turn on the service-F call light 9e depending on the belief from d. In addition, Q31A in the figure,
B shows an eraser unit and a charging unit provided around the photoreceptor drums L and D, respectively, and C shows an I/ner replenishing member provided at the upper part of the developing tank T.

Next, the operation of the apparatus configured as described above will be explained.

``When the main switch of the electrophotographic apparatus is turned on, the sequence controller operates to check whether the bias voltage of the developing unit and the heating temperature of photoreceptors 1 and D are as set. When it is confirmed that these are genuine and false, a signal is output from the sequence controller, the developing sleeve rotates, and the developer in the developing tank T is supplied to the toner concentration detector L, and the toner concentration signal is sent to the toner concentration detector L. Input to concentration range setter 2. If this concentration signal is around the lower limit value, )・Naert limit concentration detection circuit 2C
An L signal is output from the toner replenishing member drive circuit 7 to operate, and toner is replenished until an H signal is output from the toner lower limit concentration setting circuit 2c, thereby adjusting the toner concentration to an optimum range. When you press the copy start button after completing these preparations, the copy operation will start, and each time the toner density goes around the lower limit, toner will be replenished and copies will be made one after another within the optimum I/toner density range. Continue to create copies with high image quality. Needless to say,
This toner replenishment operation is performed by the toner lower limit concentration detection circuit 2c.
This is done to the extent that the lower limit value set for
The L signal is output from the 1-limit setting circuit 2b, and the data I.
is in an open state m1. When a predetermined number of copies have been made in this way, a signal is output from the sequence controller to temporarily interrupt the copying operation, and instead a standard pattern is imaged on the photoconductor tram D to the image density detector 4.
This detection signal is output to the image density setting device 5.

The setting device 5 operates to compare the image density signal with a set value and select one of the following three operations depending on the conditions.

■ When the image density exceeds the set value When the toner density is within the above-mentioned optimum range, that is, within the upper limit of the toner density setting device 2, the copying operation continues and the toner in the developing tank T is consumed. Wait for the toner density to decrease. Even though the toner density has fallen below the lower limit value, if the image density still does not reach the set value for some reason, the alarm circuit 9 is activated and the serviceman call light 9e is turned on to prompt maintenance.

II. When the image density matches the set value, the next copying operation is continued without performing toner replenishment, and a copy with the set density without thickening or thinning is created.

■9 When the image density is below the set value When the toner density is below the - limit value, the gate 3 is open, so the L signal from the image density setter 5 is input to the supply amount regulator 6. Then, the toner replenishment time corresponding to the paper size is output to the toner replenishment member drive circuit 7, and the copying operation continues.

When the scanner returns after the start of copying, the toner replenishing member C is operated for the set time to replenish toner for a predetermined number of sheets, thereby creating copies that compensate for changes in the exposure system and charging system. On the other hand, when the concentration of ).

As explained in -1-1 below, according to the present invention, a -1 limit and a lower limit are set for the toner concentration of the developer, and when the toner concentration is lower than the 1-hi limit, the set image density is achieved. The system is configured to replenish toner in a constant amount, and when the lower limit is reached, toner is replenished to exceed this limit, so the image density is constant and high quality copies with no thick or thin lines can be obtained. In addition, there is no JJC problem where toner replenishment goes out of control due to deterioration of the exposure system or charging system. Furthermore, since the image density is detected every predetermined number of sheets, not only can toner consumption and the load on the cleaning unit be significantly reduced, but the time spent on image density detection is also reduced, and the copy speed is reduced. ” You can get two.

[Brief explanation of the drawing]

The figure is a diagram showing an example of a device used in the present invention. 1... Toner density detector 2... Toner density range setting device 3... Image density detector Applicant Ricoh Co., Ltd. - Agent BU "Buried soil" Kei Nishikawa Katsuhiko Kimura 4. +f61 Agency Director Kazuo Wakasugi 1
．． Display of 7 items Patent Order No. 233150 of 1982 2, Name of the invention 'rli j-Method for controlling I/ner concentration in photographic equipment 3, Person who performs supplementary IF Relationship with 1 item Applicant Address Tokyo Metropolitan University IJ , 1-ku Nakamagome 11'I" + 3-6 Name (674) Ricoh Co., Ltd. Representative Takeshi Oue 4, Agent address Sankyo Building, 2-1-2-11 Koishikawa 2-chome, Bunkyo-ku, Tokyo Name (8256) Patent attorney Keiji Nishikawa 6, Number of inventions increased by amendment 7, Detailed explanation of the invention in the specification subject to amendment 8, Contents of supplement rH As attached (1) Specification No. 1 , in i, from t 20th line 11 to 2nd page 1st line 11, ``Using an F sensor shade toner 1 agricultural j11 detector that detects 1:'4 contact,'' is changed to ``When changes, the magnetic permeability changes. This is corrected by using an inductance detector that takes advantage of this. (2) I11, page 2, line 4, line 11 to line 5, line 11, “
Delete "P sensor etc." (3) 71) Page 3, line 2 1] [F sensor A9
・' is supplemented with j of ``interface detection element, etc. j1:''.
"of the sensor, etc." is corrected to "of the reflective image density detection element 'I."

Claims (1)

[Claims] The toner density in the developing tank is constantly detected, and this detection signal is compared with the preset "-eye density" and lower limit density.
When the toner density is higher than the limit density, change this to -
1-IUI is replenished into the tank, and when the upper limit density is below 1i1, a predetermined copying process is carried out so that the image density detected every r after the predetermined number of copies is made becomes the set density. Toner concentration control power in an electrophotographic apparatus that replenishes an amount of I. toner according to the number of copies and copy paper size.