JPH0797250B2 - Developer concentration control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a developer concentration control device, and more specifically,
The present invention relates to a developer concentration control device applicable to a developing device using a two-component developer of toner and carrier.

(Prior Art) Conventionally, in a copying machine using a two-component developer in which a magnetic carrier and toner are mixed, there is one in which a magnetic detection device is provided to magnetically detect the mixing ratio of the developers. For example, there is a device disclosed in Japanese Utility Model Publication No. 61-46463. In this case, variations in the density detection device itself, variations in the state of the developer existing in the vicinity of the detection device due to variations in the dimensions of each part of the development device, variations in the magnetic permeability of the developer carrier, etc. I was adjusting the density control level.

However, when adjusting the density control level described above, the detection output is also affected by the charge state of the developer.Therefore, it is necessary to sufficiently stir until the charge state stabilizes and to adjust the volume or switch during the stirring operation. However, there is a problem that the work is complicated and setting variations due to individual differences are likely to occur.

(Object) It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a developer concentration control device capable of easily setting the toner concentration of a two-component developer.

(Structure) In order to achieve the above-mentioned object, the present invention includes a detection unit that detects a mixing ratio of a developer composed of toner and a carrier, a stirring unit that stirs the developer, a non-volatile storage unit, and the detection unit. Sample storage means for sampling and storing the output at predetermined time intervals and switching means for switching between the copy operation control mode and the toner concentration setting mode are provided, and the stirring means when the toner concentration setting mode is selected by the switching means. The concentration data from the detection means is stored as storage data by the sample storage means, the storage data before and after are compared, and the storage data at the time when the change amount of the storage data is equal to or less than a predetermined amount is stored. It is characterized in that it is stored in a non-volatile storage means and this stored data is used as threshold data for density control.

Hereinafter, a specific description will be given based on an embodiment of the present invention.

FIG. 1 is a sectional view showing a developing device, FIG. 2 is a block diagram showing the entire control system, FIG. 3 is a block diagram showing an input circuit of a density detecting means, and FIG. 4 is a flow of a toner density setting control mode. FIG. 5 is a flow chart of the copy operation control mode.

As shown in FIG. 1, in the developing device 1, a developing roller 2, a pair of scooping rollers 3 and 4, and a stirring roller 5 are well known.
An agitator 6, a toner supply pipe 7 and the like are provided, and detection means 9 for detecting the mixing ratio of the developer 8 composed of toner and magnetic carrier is provided on the bottom side of the developing device 1. . The developing roller 2, the drawing roller 3,
4, the stirring roller 5, and the agitator 6 serve as stirring means for stirring the developer 8.

The detecting means 9 magnetically detects the mixing ratio of the toner and the magnetic carrier. As shown in FIG. 3, the analog signal due to the change of the mixing ratio detected by the detecting means 9 is an analog signal. / Input to the central control unit (CPU) 11 via the digital (A / D) conversion circuit 10.

By the way, the two-component developer 8 left for a long time has a low charge amount, and gradually increases toward a stable state with the lapse of stirring time. This change in the charged state affects the output of the magnetic density detecting means 9. Even if the developer having the same toner concentration is detected by the magnetic detection unit 9 and the charged charge amount is low, the output is shifted to the low toner concentration side. Therefore, it is necessary to perform the density setting work in a state where the charged state is stable.

In view of this, in the present embodiment, the CPU 11 serving as the sample storage means samples the density data from the detection means 9 at regular intervals during the stirring state of the developer 8 to determine whether the stable state has been reached, and the density data before and after it is sampled. The change amount (ΔD) of the value is less than or equal to a predetermined amount (ΔD ₀ ) is calculated, and the density data stored in the CPU 11 from the detecting means 9 at this point is used as a threshold value for density control. The data (D ₀ ) is stored in a non-volatile storage means (described later).

Specifically, when the density data is output as D ₀ , D ₁ , ..., The rate of change is calculated by the moving average method as follows, and the threshold value D ₀ is obtained. For example, When the equation (2) is calculated, the change amount of the density data is smaller than the predetermined amount ΔD ₀ . The D ₀ calculated as above becomes the threshold data. Thus, using the average value of the data results in more accurate discrimination.

The control system of each unit by the CPU 11 is as shown in FIG. 2, and the CPU 11 has an operation unit 12 having a ten-key, a number display means, etc., a normal copy operation control mode and a toner density setting control mode. Switching means 13 consisting of a mode switching switch for switching between
5 and a driver 19 for driving the main motor 16, the developing motor 17, the toner replenishing motor 18, etc. are electrically connected to each other.

Next, the operation of the above embodiment will be described based on the flow chart of FIG.

First, the toner density setting control mode is set by the switching means 13 (4-1). Normal copy operations are not performed in this mode. In this state, the density setting control mode is started as a key operation, for example, an operation of pressing the copy start button of the operation unit 12. By this mode start, various parts required for stirring the developer are activated. That is, in this embodiment, since the developing drive motor is set independently, if only the developing motor 16 is started, the developing device 1 is driven through the drive transmission system.
The stirring means 2, 3, 4, 5 and 6 in the inside rotate (4-3), and the developer 8
Are moved and stirred.

Before the stirring operation is started, the minimum concentration data is set in the CPU 11 or the like (4-2). Then, the concentration data (D _x ) of the developer 8 output from the detecting means 9 during the stirring operation is CP.
Sample at U11 (4-4). This color sampling is performed every 4 to 5 seconds on average for color.

As described above, the average values R _n and R _{n-1 of} the respective concentration data D _{0 to} D _n output from the detecting means 9 by sampling the concentration data n times (stored in the CPU 11 and used as storage data). (4-5), and the difference (change amount ΔD)
Is less than the predetermined value ΔD ₀ (4-6), the CPU 11 stores the stored data of R _n at that time as the density control threshold data (D ₀ )
Is stored in the non-volatile storage means 15 (4-7) and stirring is stopped (4-8). At this time, the mode end may be displayed on the display unit of the operation unit 12.

After the above-mentioned toner density setting control mode is completed, the state of the copying machine is returned to the copy operation control mode by the switching means 13.

When the copy start button of the operation unit 12 is pressed in this mode to start the mode (5-1), various parts required for the copy operation are activated (5-2). Then, the toner density data (D _x ) sampled (5-3) during the copy operation and the density control threshold value data (D ₀ ) already set and stored in the nonvolatile storage means 15 are stored in the CPU 1
1 is compared (5-4), if D ₀ > D _x , the toner replenishment motor 18 is operated to replenish toner from the toner supply pipe 7 (5-5), and if D ₀ <D _x Stop toner supply (5-6). As a result, the density control is performed.

After the copy operation is stopped (5-7), the operation control of various parts necessary for the copy operation is stopped (5-8).

Although a switch independent of the operation unit 12 is provided as the switching means 13, for example, a special key in the operation unit 12 (an operation key that is not used in a normal copying operation) is double-pressed or a numeric keypad is used. It is also conceivable to give the mode switching function of the switching means 13 by hammering or a combination thereof.

(Effect) As described above, a developer concentration control device is provided which can simplify the threshold level adjustment work of the density control to determine the threshold value by detecting the change of the density data and reduce the variation of the setting. it can.

[Brief description of drawings]

The drawings show one embodiment of the present invention, FIG. 1 is a sectional view showing a developing device, FIG. 2 is a block diagram of a control system, FIG. 3 is a block diagram of an input circuit of a density detecting means, FIG. Figure 5 is a flow chart. 2,3,4,5,6 ... stirring means, 8 ... developer, 9 ... detection means, 11 ... sample storage means (CPU), 13 ... switching means, 14 ... timing means, 15 ... ... Non-volatile storage means, D ₀ ... threshold value data, D _x ... toner density data.

Claims (1)

[Claims] 1. A detection means for detecting a mixing ratio of a developer composed of toner and a carrier, a stirring means for stirring the developer, a non-volatile memory means, and outputs of the detection means are sampled at predetermined time intervals. The sample storage means for storing and the switching means for switching between the copy operation control mode and the toner concentration setting mode are provided, and when the toner concentration setting mode is selected by the switching means, the agitating means is operated to store the sample storage means. Therefore, the concentration data from the detection means is stored as storage data, the storage data before and after is compared, and the storage data at the time when the change amount of the storage data becomes equal to or less than a predetermined amount is stored in the nonvolatile storage means, A developer concentration control device characterized in that the stored data is used as threshold data for concentration control.