JPH04199079A - Recording device - Google Patents

Abstract

PURPOSE:To precisely keep the toner concentration constant at all times by changing the control level according to the service condition of a developing agent, and performing the toner refill control density. CONSTITUTION:When the toner in a developing agent is consumed, the output voltage of a sensor 1 rises, and the driving time for a toner refilling motor of a toner refilling means 7 is obtained from the output voltage of the sensor 1 by reference to a lockup table LUT 3. Thus the motor is driven for a time in accordance with the output of the LUT 3 to conduct refill of the toner. When the number of sheets for copying exceeds 5,000, the condition of the developing agent such as bulk density etc. will also vary, so that a table selecting means 5 receives data about the number of copies, selects table out of the LUT 3, and determines the motor driving time. That is, the bulk density increases even with proper toner concentration in the developing agent, so that the output voltage of the sensor 1 will also rise, which should shift the table data as a whole. Thereby toner with proper concentration is refilled.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a recording device used in an image forming apparatus such as an electrophotographic copying machine, and more specifically to a recording device that can accurately control toner density. Regarding equipment.

<Background of the Invention> An electronic copying machine exposes a charged photoreceptor (hereinafter a photoreceptor drum will be explained as an example) to light according to document information to form an electrostatic latent image, which is then converted into a visible image using toner. This device transfers and fixes this visible toner image onto transfer paper. In recent years, this type of electronic copying machine has been used in all fields of industry.

Incidentally, a two-component developer consisting of toner and carrier (iron powder) is used in the recording device used in this type of electronic copying machine. Toner is gradually consumed during development depending on the type and number of documents, and the toner concentration in the developer gradually decreases, so it is necessary to replenish toner as appropriate. If this toner density becomes too dark, the resulting image density may become too dark, fogging may occur, or it may cause scattering.
Image quality deteriorates significantly.

On the other hand, if the toner concentration decreases, the image density will continue to decrease and the durability of the developer will decrease rapidly. For example, if you compare the toner density of 5% and 2%, the durability of the 2% toner may be half of that of 5%.

Therefore, the mixing ratio of toner and carrier must always be kept constant. For this purpose, the toner concentration in the developer is detected by some means, and toner is replenished so that the detected concentration value matches a predetermined standard density value.

To detect the toner concentration in a developing device using a two-component developer, there is a toner amount detection method using inductance. This detects the toner concentration by placing an inductance sensor with a coil in the developer using the carrier or magnetic material contained in the developer. Specifically, when the toner concentration changes, Focusing on the fact that the mixing ratio of toner and carrier changes and the magnetic permeability fluctuates, the magnetic permeability of the developer is measured to determine the toner concentration.

Then, the output voltage of the inductance sensor is compared with a reference voltage, and toner is replenished so that the output voltage of the inductance sensor becomes equal to the reference voltage, and as a result, the toner concentration is controlled to be constant. Such technology is disclosed in Japanese Patent Publication No. 63-28305 and Japanese Patent Publication No. 64-28305.
It is described in No. 5299.

FIG. 12 is a characteristic diagram showing an example of the characteristics of an inductance sensor. The characteristics of the sensor are such that as the toner concentration decreases, the sensor output voltage increases. The output voltage can be adjusted by controlling the control voltage VC applied to the sensor. Therefore, when initializing the developer at the standard concentration (for example, 7%),
The control voltage VC is determined so that a predetermined voltage (for example, 2V) is obtained. In this figure, the control voltage is VC2, and this VC2 continues to be applied thereafter.

<Invention or problem to be solved> Yellow and cyan for color copiers.

Various colors are reproduced by overlapping four colors: magenta and black. Therefore, from the viewpoint of color balance, the toner density of each color must be accurately controlled.

By the way, when a developer is used, the key density (the weight of the developer per unit volume) changes. This behavior may be reversed depending on the type of developer, but by repeating stirring and circulation within the developing device, the developer becomes in a state equivalent to being compressed from its initial state. In this state, the amount of toner and carrier per unit volume increases.

However, since the toner concentration is detected only based on the amount of carrier, the output of the sensor increases, which is mistakenly interpreted as a decrease in the toner concentration.

Therefore, in the developing device, toner is replenished, and there is a possibility that the toner concentration may actually become excessive. This increases the density of the output image. In this case, in a color image, the state of use of the developer for each color is different, so there is a problem that the color balance becomes out of order and color reproducibility deteriorates.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to realize a recording apparatus that can accurately and always keep the toner density constant.

<Means for Solving the Problems> The present invention solves the above problems by adjusting the toner concentration of a developer consisting of a magnetic carrier and a non-magnetic toner by adjusting the magnetic permeability based on the ratio of magnetic carrier per fixed volume of the developer. The present invention is characterized by comprising: a sensor that detects a change in the developer, a usage state detection means that detects the usage state of the developer, and a control means that varies the control level according to the usage state of the developer and controls toner supply. That is.

Function> When toner is replenished according to the output of the sensor that detects the toner concentration, the control level of the toner replenishment control is made variable according to the usage status of the developer detected by the usage status detection means 8. . As a result, since the toner replenishment time is determined based on data that matches the usage state of the developer, accurate toner density control is performed.

<Examples> Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the electrical structure of a recording apparatus according to a first embodiment of the present invention.

In this figure, 1 is a sensor that detects the developer toner concentration as a change in inductance value, 2 is a control voltage generating means for applying a control voltage to generate a predetermined output voltage from the sensor 1, and 3 is a predetermined sensor. This is a lookup table (LUT) that compares the output voltage with data in the table and outputs the toner replenishment time. Within this LUT B, a plurality of tables are prepared based on changes in characteristics depending on the number of times the developer is used. Reference numeral 4 denotes a use state detection means for detecting the use state (number of times of use, etc.) of the developer, 5 a table selection means for selecting a table to be used in the LUTB based on the detection result of the use state detection means 4, and 6 a LUT.
A control unit that controls 1.10-supply based on the output value of
Reference numeral 7 denotes a toner replenishing means for replenishing toner into the developer according to a command from the control section 6.

The operation of the apparatus of this embodiment configured as described above is as follows.

When an initial setting instruction is given, the stirring means in the developing device stirs the developer set to the standard concentration for a certain period of time (until the toner and carrier are well mixed).

After stirring for a certain period of time, the output electrons of the sensor] reach a predetermined value (
For example, the control voltage for the sensor 1 is adjusted by the control voltage generating means 2 so that the voltage becomes 1.9 V). After this, the control voltage generating means 2 generates a constant control voltage.

In this case, when the toner in the developer is consumed, the output voltage of the sensor increases. Therefore, the driving time of the toner replenishing motor of the toner replenishing means 7 (proportional to the amount of toner replenishment) is obtained from the output voltage of the sensor 1 using the LUT 3.

Immediately after initial settings are made, toner density control is performed using Table 1 shown in FIG. 2 for a while (for example, up to 5000 copies of each color).

Therefore, the toner is consumed and the output voltage of sensor 1 becomes 1.
When the voltage exceeds 9 V, the toner replenishing motor of the toner replenishing means 7 is driven for a time corresponding to the output of the LUT 3 to replenish toner. For example, every time one sheet is copied, data is sampled three times from the sensor every two seconds, and toner is replenished for a maximum of six seconds (three times of two-second replenishment).

When the number of copies exceeds 5,000, the state of the developer such as the bulk density of the developer changes, so the table selection means 5 or L that receives the data of the number of copies from the copy counter etc.
Table 2 (see FIG. 3) in the UTB is selected to determine the motor drive time for toner replenishment. That is, even if the toner concentration of the developer is appropriate, the bulk density increases, so the output voltage of the sensor 1 also increases. Therefore, the entire data in the table is increased by 0.1.5V. As a result, even if the bulk density of the developer changes, an appropriate amount (a degree) of toner can be replenished.

Similarly, the table selection means 5 sequentially selects tables as shown in FIGS. 4 and 5 every time 5000 sheets of each color are copied. The number of copies described above is determined from the counter of the developing device for each color.

As a result of conducting an experiment with such a configuration, it was possible to control the concentration to 7±0.degree. 3% when the appropriate value of the 1.tonner concentration for each color was 7%. As a result, even in the case of color copying, color balance deviations do not occur.

In the above description, a plurality of tables may be prepared in which the data of the sensor output voltage portion is changed, or a plurality of tables may be prepared in which the data of the motor drive time portion is changed. Also,
The contents of each table in the LUTB may be determined depending on the characteristics of the developer (whether the sensor detection voltage changes as it is used). Further, the LUT 3 may be prepared by changing the number of copies to be used for each color depending on the type of developer.

In this embodiment, since a device that replaces the developer every 20,000 sheets is used, it is sufficient to determine whether the data is up to 20,000 sheets depending on the type of developer.

FIG. 6 is a configuration diagram showing the configuration of a second embodiment of the present invention. The difference from the embodiment shown in FIG.
The point is that the control voltage generating means 2 generates a control voltage for the sensor according to the detection result of the sensor. And L.U.
As before, only one type of table is prepared in the TB.

In this configuration, the control voltage applied to the sensor is changed depending on the number of times the developer of each color is used, so that a constant sensor output is always provided with respect to the toner concentration of the developer.

When pre-measured with a certain developer, the data in LUTB was from the table shown in Figure 2, and the control voltage for sensor 1 was set to 7.02V at the initial setting (toner concentration 796). The desired output was obtained. At this point, after 5000 copies, the control voltage should be increased to 6.
Similar results were obtained by setting the voltage to 4V.

Therefore, as shown in FIG. 7, the control voltage generating means 2 outputs o, os, and
v Gives a falling control voltage.

As a result of conducting experiments with such a configuration, it was possible to control the toner density to 7±0.degree. 3% when the appropriate value for each color toner density was 7%. As a result, even in the case of color copying, no deviation in color balance occurs.

Note that the rate of change in the control voltage may be determined depending on the characteristics of the developer.

In both the first and second embodiments, control accuracy is further improved by adjusting the sensor output voltage in LUT 3 and offsetting it with respect to the table used, depending on the temperature and humidity inside the developing device. do. Preferably, the sensor output voltages used in the above embodiments under high temperature and high humidity conditions are as shown in FIGS. 2 to 5 as shown in FIGS. 8 to 11 (only FIG. 9 is used in the second embodiment). Control accuracy is improved by offsetting the data.

In the two embodiments described above, the data group in the LUTB such as the table or the control voltage is changed depending on the number of copies, but other configurations are also possible. For example, since the amount of toner used is estimated based on the cumulative rotation time of the toner replenishing motor in the toner replenishing means 7, if the selection 1 control voltage of the table is changed based on this cumulative value, Accurate toner density control is possible.

It is also possible to refer to the reflection density of the toner image on the photoreceptor. Furthermore, it is also possible to refer to the temperature and humidity inside the recording apparatus depending on the characteristics of the developer. Furthermore, if the writing system uses a writing density or a reading system using a CCD, it is also possible to refer to its output signal.

In the above embodiments, the table, motor drive time, etc. described above may be changed when the purpose is to keep the toner density constant or when changing the toner density as necessary to change the image density. I can handle it.

<Effects of the Invention> As explained above, in the present invention, the toner concentration of a developer consisting of a magnetic carrier and a non-magnetic toner is detected as a change in magnetic permeability based on the ratio of magnetic carrier per fixed volume of the developer. The present invention is configured to include a sensor for detecting the use of the developer, a use state detection means for detecting the use state of the developer, and a control means for controlling the toner replenishment by varying the control level according to the use state of the developer.

As a result, when toner is replenished in response to the output of the sensor that detects toner concentration, the control level (toner replenishment time, control voltage to the sensor) is adjusted according to the usage state of the developer detected by the usage state detection means. ) is selected.

As a result, since the toner replenishment time is determined based on data that matches the usage state of the developer, accurate control of toner concentration is performed regardless of the usage state of the developer.

Therefore, it is possible to realize a recording apparatus in which it is easy to maintain the toner concentration of the developer accurately and always constant.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a developing device according to a first embodiment of the present invention, and FIG. 2 is an explanation showing the contents of a first table used in the developing device of the embodiment shown in FIG. 3 is an explanatory diagram showing the contents of the second table used in the developing device of the embodiment shown in FIG. 1, and FIG. 4 is an explanatory diagram showing the contents of the second table used in the developing device of the embodiment shown in FIG. FIG. 5 is an explanatory diagram showing the contents of the fourth table used in the developing device of the embodiment shown in FIG. FIG. 7 is an explanatory diagram showing the details of the control voltage applied to the developing device of the embodiment shown in FIG. 6. FIG. Figure 9 is an explanatory diagram showing the contents of table 2' used under high temperature and high humidity conditions. Figure 10 is an explanatory diagram showing the contents of table 2' used under high temperature and high humidity conditions. Figure 11 is an explanatory diagram showing the contents of the 4' table used under high temperature and high humidity conditions. Figure 12 is the characteristics of the sensor that detects toner concentration. FIG. ] Sensor 2・Control voltage generating means 3...LU
T4・Usage status detection means 5・Table selection means

Claims (4)

[Claims] (1) A sensor that detects the toner concentration of a developer consisting of magnetic carrier and non-magnetic toner as a change in magnetic permeability based on the ratio of magnetic carrier per fixed volume of the developer, and a sensor that detects the state of use of the developer. 1. A recording apparatus comprising: a use state detection means; and a control means for controlling toner replenishment by varying a control level according to a developer use state. 2. The recording apparatus according to claim 1, wherein the control means receives the detection result of the sensor and selects a data group in a look-up table that outputs toner replenishment time to vary the control level. (3) The recording apparatus according to claim 1, wherein the control level of the control means varies the control voltage applied to the sensor. (4) The recording device according to claim 1, wherein the usage status detected by the usage status detection means is usage frequency.