JPS58108554A - Controlling method for electronic copying machine - Google Patents

Abstract

PURPOSE:To obtain images having proper density independently of the deterioration of a developer and a lamp, and humidity by controlling a toner feeding quantity and development bias or a charging current on the basis of the values obtained by measuring the density of a toner image of a reference target and surface potential. CONSTITUTION:The reference target 3 is exposed by a lamp 4 and projected on a photosensitive drum 6. The generated electrostatic image is developed by a developing device 7 and the density of the generated toner image and surface potential are detected by a sensor 10. The quantity of toner charging is calculated from the density and surface potential, and when the calculated value is low, the toner in the developing device 7 is agitated. When the density is low, a toner feeder 9 is continuously actuated and voltage applied by a development bias electrode 8 is reduced. If the bias voltage reaches its lower limit, a current to a charger 25 is increased. At the time of high density, the same kind of control is executed in the reverse direction.

Description

DETAILED DESCRIPTION OF THE INVENTION This i*Fi method exposes a reference target on a photoreceptor in advance, develops it, detects the density and potential of the toner, and uses the obtained detection signal to determine the copying process. An electronic copying system that comprehensively controls the toner supply device, developing bias voltage, charging/exposure system, etc. according to a preset mode to keep the toner supply device, developing bias voltage, charging/exposure system, etc. Concerning a control method.

The image quality of copies obtained with conventional types of copying machines, II.
Maintain a constant concentration of IIK copying! As additional devices, devices that automatically control the amount of toner supplied and devices that control the developing bias voltage are used. These devices improve the stability of image quality by detecting changes in the amount of transmitted light, electrical resistance, magnetic resistance, etc. of the developer and automatically maintaining the toner content in the developer at a constant level. It is something. However, in these devices, the toner content is controlled to be 1:1 even when the agent or exposure lamp deteriorates and the light or humidity increases, so on the contrary, it is difficult to obtain a good copy. image quality deteriorates. A copying machine using a magnetic brush developing device in 41 has the disadvantage that it is susceptible to these problems. For example, the method disclosed in Japanese Patent Application Laid-Open No. 55-55349 has been proposed to improve this drawback, but since this method uses only toner II& as a signal, the developed image density is constant and t1 Since it is unclear whether the toner charge has the amount of charge i necessary for transfer,
There are problems that can cause secondary failures such as the following: That is, in general, development in this type of copying machine is performed by electrical force due to charging and mechanical force due to friction. When the amount of charge is large, development is carried out mostly by electric force (1&), but when the amount of charge is small, mechanical force becomes larger than electric force.

However, the toner mechanically attached to the photoreceptor hardly contributes to transfer to paper.

Therefore, even if the amount of toner adhering to the photoconductor is constant, if the amount of charge on the toner changes, the amount of toner transferred to the paper will decrease and the density will decrease, and at the same time, the amount of toner that will not be transferred to the paper will decrease.
The toner remaining on the surface of the photoconductor adheres to the paper's illustration ag, resulting in low-density, high-coverage copying.Even if you simply control the toner immersion level on the photoreceptor surface to a constant level, it will not be possible to produce an image without fogging. This method has the disadvantage that it is not possible to obtain a stable copy of the densities.

The present invention was made with the aim of overcoming the drawbacks of such conventional control devices, and by integrally controlling the current bias voltage, charger, exposure system, etc. in the toner supply mold, It is an object of the present invention to provide a control method for an electronic copying machine that allows copies of stable image quality to be obtained at all times.

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows an electronic copying machine employing the control method and control device of the present invention, in which an original table 2 (not shown) for placing an original is provided above the mouth of the main body of the copying machine. J [A reference target 3 and an exposure lamp 4 that moves along the document table 2 are provided below the stacking table 2, and a trap is provided so that the document and the reference target can be exposed to the exposure lamp 4. .

The reflected light from the original or the reference target 3 passes through the optical system 5 and reaches the photoreceptor 6 in the copying machine main body 1, forming an electrostatic latent image on the circumferential surface of the photoreceptor 60. The electrostatic latent image on the photoreceptor 6 is transferred to the next developing device)
It is developed into a Sytoner image. The developing device 7 has a developing electrode 8 to which a high voltage is applied along the circumferential surface of the photoreceptor 60, and the developer containing the toner supplied from the toner supply device 9 is applied to the photoreceptor 6. It develops the electrostatic latent image of
A detector 10 for detecting the density of the toner image of the reference target 3 formed on the photoreceptor 6 is provided above the developer. Detector! O is a combination of a reflection type densitometer 101 consisting of a light emitting diode and a photodiode, and a surface electrometer 102, for example.
The density signal and the potential signal detected by the detector 10 are provided to correspond to the toner image of the reference target 3 formed in one part, and the input circuit +2t- is controlled by the processor 13. Via microphone W:f
Nvieta 1IIll! -6, and a control signal is calculated as follows.

When copying starts, the photoconductor 6 is charged and charged by 25.
When the 0-order rIi is uniformly charged, the surface of the photoreceptor 60 becomes Va as shown in FIG. When the potential is measured, it becomes Va (V). When the photoconductor 6 is further rotated and the surface of the photoconductor 6 is irradiated with flK unnecessary image erasing light source 11, the potential of the toner adhesion part disappears, and the potential is changed to the surface potential. When measured at a total of 1 (h), it becomes Vt (Y) in FIG.

Since it is known in advance that the following relational expression holds between the toner charge Qt and the above-mentioned Vtff, the toner charge Qs value is stored in the 1-mic a computer device 16 in advance, and a new surface electrometer IO! The amount of charge of the developed toner is calculated from the value Vl measured by the following formula.

V electric = AQ? t・・・・・・・・・・・・・・・−・−
(1) The value V+ measured by the reflective densitometer 101 at the same time as the measurement of the amount of charge (1, -1) determined by the toner used
(V)], calculate the weight per unit area of the nine toners used in development. That is, since the relationship between the value Vt (V) measured by the reflection ms seismic intensity meter 01 and the toner weight Mwp/aA can be expressed by the following equation (3), this should be stored in the microcomputer system [16] in advance.

M=84oF(y7-) 111/d--・--
(3) The charge amount Q of the developer, where t is a constant, can usually be expressed as sq/fl, and can be calculated from the above-mentioned values Qt and M as follows.

Therefore, by executing the above equation by the microcombiner device 16, it is possible to calculate the charge amount of the developer as a tribo value which is normally treated.

! The value calculated by the output device 16 is outputted to various control circuits 15 via the output circuit 14. Various control circuits 15 include, for example, a development control circuit I5 and an exposure control circuit 1.
52.) Toner supply amount control circuit 15x% Developer agitator control circuit 154 or the like, when the concentration or surface potential detected by the reflection type densitometer 1 (h) or the surface potential meter 101 deviates from the reference value, These control circuits are charged and
The charging current 15a of 25 and the developing bias voltage 1 of the developing device)
5b1 Light amount of exposure lamp 4: 158%) Toner supply amount 15d of toner supply device 9, rotation 15@ of a developer stirring mechanism (not shown) in developing device 7, etc. are controlled.

That is, FIG. 5 is a flowchart showing an example of controlling the toner supply device 9 and the developer stirring mechanism. Next, to explain this, the specific surface potential Vt detected by the detector 100 and the surface potentiometer 101 and the density detection 4110tK are shown in FIG. As mentioned above, the charge amount Qt and the developer weight M are calculated based on the detected nine density signals, and the tribo value Q is calculated from these values. The developer stirring mechanism is compared with the reference value X (20), and if it is higher than the reference value X, the developer stirring mechanism does not operate (21-), and if it is lower, it operates (22) and stirs the developer in the imager! , the density detected by the density detector 10x is displayed in a table 64, and this detected value is compared 65 with a preset reference value, and if the detected value is an appropriate image density, the As shown in 5@, only an instruction 66 is given to the toner supply amount control circuit ISg to operate the drive mode J of the toner supply device 9 intermittently, but the When the high value tth indicates a low value, after issuing a stop instruction 68 or a continuous drive instruction 67 to the drive motor of the toner supply device 9, the charging current of the charger 25 and the bias voltage of the current power supply 116 are changed. For example, if the detected image density value is low, an instruction for continuous drive is given to the drive motor of the toner supply device 9, and then the charging current of the charger 25 is increased or decreased according to the value of each parameter. A judgment 6g is made as to whether or not it meets the standard.

If this and the self-charging current are at the standard value, further Kllll
It is determined 69 whether the potential of the l-electrode 8 is already at the lowest potential within the settable range. If it is possible to lower the bias potential by a certain amount in 4h cycle ζζ,
The level of the bias potential will be lowered by one step at 70-degrees, but if the bias potential is already at a low potential and the bias potential cannot be lowered any further, the charging current will drop to the reference value. Judgment 7 whether the charging current is the maximum within the settable range in the same way as when there is no
1 is performed. If it were possible to increase the charging current tube by a certain amount, the charging current level would be raised by one step in flow 72, but the charging current is already at its maximum and cannot be increased any further. In this case, this subroutine will be exited without issuing an equivalent instruction.

The above has explained the control mode when the image immersion degree is lower than the appropriate value, but if the inverse Km image density is higher than the appropriate value, first the toner supply device 9 is stopped every time the toner supply device 9 is driven 68
This state continues until an instruction to restart driving is issued again.

After this, it is determined 78 whether the charging current is at the reference value, and if the charging current is at the reference value, it is further determined 74 whether the bias potential of the developing electrode 8 is at the highest potential within the settable range. be done. 4. If it is possible to increase the bias potential, the bias potential is increased by one step in flow 75. However, if a very high potential is already applied, the charging current of the charger 25 is increased. As in the case where the charging current is not within the reference value, a determination flow is made as to whether the charging current is the minimum within the settable range. If the charging current is not at its minimum but can be lowered by a certain amount, it would be useful if the judgment result regarding the pack ground concentration in the copying operation immediately before this copying is also used in the judgment. ], if this pack-ground concentration is not low, the charging current will be lowered by one step in flow 78, and in other cases it will escape from this layer without issuing any instructions.

As described in detail above, this invention detects the toner vorticity and toner charge amount of the reference target exposed to the photoreceptor 0-@ at the time of multiple zero, and then controls the ratio control signal obtained by detecting the toner vorticity and toner charge amount. Since various control circuits can be controlled simultaneously or individually according to the pre-installed nine modes, toner can be supplied without being affected by the installation of the duplicating machine body** or changes over time in each part of the copier. It is possible to comprehensively control the developing bias voltage in the main mold, charging/exposure system, etc., thereby making it possible to always obtain copies with stable image quality.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; Fig. 1 is an overall configuration diagram of a multi-military aircraft, Fig. 2 is a block diagram of a control system, and Fig. 3 is a diagram showing changes in photoreceptor surface potential. , FIG. 4 is a diagram showing the relationship between the amount of toner adhesion and the output voltage of a reflective metal densitometer that detects it, and FIG. 5 is a flowchart showing the operation. 3 is a reference target, 7 is a developer, 8 is a current tube electrode, 25
is a charger. Representative: Fuji Xerox Co., Ltd. Patent attorney: Masaaki Yonehara Patent attorney: Tadashi Hamamoto

Claims (1)

[Claims] Determine the toner concentration and surface potential from the toner record of the reference target 3 formed on the photoreceptor 60 Table 1iK, compare the calculation result of this detected value with a preset reference value, and use the obtained value to determine the current A method for controlling an electronic copying machine, comprising the step of controlling at least the bias voltage applied to the developing electrode 8 of the developing device or the charging current of the charger 25 at the same time as controlling the amount of toner supplied to the developing device 7.