JP2008096763A - Toner density control device, developing device and image forming apparatus including the same, and toner density control method - Google Patents

Abstract

Provided is a toner density control device in which a limiter position of a target toner density sensor does not shift even when the developing device is mounted on another image forming apparatus and reused.
An image carrier, a two-component developing device, a toner density sensor, control means for changing a control signal value to adjust an output signal of the toner density sensor, a toner replenishing device, and a toner density control device Control signal value adjustment mode on / off in a toner concentration control apparatus applied to an image forming apparatus that determines the amount of toner replenishment to the developing device based on the difference between the output value of the toner density sensor and a reference value A storage device and a control signal storage device, the control signal storage device stores the changed control signal, the toner supply amount is determined based on the stored control signal, and the adjustment mode on is selected After changing the developing device to another image forming apparatus, the control signal (Vcnt) is changed and adjusted.
[Selection] Figure 6

Description

The present invention relates to a toner density control device applied to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, a developing device and an image forming apparatus provided with the same, and a toner density control method. The present invention relates to a toner density control device to which a two-component developer including the same is applied, a developing device including the same, an image forming apparatus, and a toner density control method.

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying apparatus, a two-component developing device that performs development using a two-component developer containing a magnetic carrier and toner, and a one-component developing device that performs development using only toner Is known.
The two-component developing device usually includes a magnet roller formed of a magnet body having a plurality of magnetic poles therein, and includes a cylindrical developer carrier (hereinafter also referred to as a developing sleeve) that is rotatably supported. In a two-component developing device, a two-component developer including a magnetic carrier to which toner is attached is carried on the surface of the developing sleeve and conveyed to a developing area that is a portion facing the image carrier, forming a magnetic brush to remove the toner. The electrostatic latent image is developed by supplying it to the image carrier. In such a two-component developing device, since the toner is charged by stirring and mixing the magnetic carrier and the toner, the chargeability of the toner is stable, and a relatively stable good image can be obtained.
However, in the two-component developing device, the toner concentration fluctuates on the basis of carrier deterioration or toner consumption, and the mixing ratio of the toner and the magnetic carrier changes. Replenish. On the other hand, the one-component developing device performs development by transporting the toner carried on the surface of the developer carrying member to the development region. Like the two-component developing device, the one-component developing device has a carrier deterioration or toner concentration control device. Although there is no disadvantage that it must be provided, the chargeability of the toner is difficult to stabilize.

Incidentally, in the two-component developing device, the triboelectric charge amount of the developer varies depending on the environment, running conditions, mechanical conditions, sensor variations, and the like. If control is performed so that the adhesion amount of the pattern becomes constant using an optical sensor with respect to the change in the charge amount, the charge amount becomes substantially constant, but there is a problem that the toner density fluctuates. In particular, if the toner concentration exceeds a certain value due to low temperature humidity, carrier charge amount fluctuation, etc., the coverage of the carrier is limited, so the number of sites on the carrier that frictionally charges the replenished toner decreases. In addition, poorly charged toner is generated, causing toner scattering, background contamination, and the like. On the other hand, when the charge amount of the developer is reduced and the pattern adhesion amount constant control is performed, the toner density is lowered, and problems such as insufficient image density and carrier adhesion in a solid image occur.
In order to avoid such a problem, for example, a method has been proposed in which a limiter is provided in the reference value of the output value of the toner density sensor, and the output value is controlled to a predetermined value or less. According to this control method, the increase or decrease in the environmental toner concentration over time can be suppressed to some extent. In addition, according to this method, even when the sensitivity differs for each toner concentration sensor, by adjusting the control voltage of the toner concentration sensor when the developer is in the initial stage, variations in sensitivity among the sensors are eliminated. Is that you can.

As a conventional technique related to a toner density sensor or an image forming apparatus including the toner density sensor, for example, Patent Document 1 was developed for the purpose of accurately detecting an abnormality of a developing machine and minimizing the influence on each part. An apparatus for charging an image carrier, an exposure device for forming an electrostatic latent image on the charged image carrier, and a two-component developer comprising toner particles and carrier particles. In an image forming apparatus comprising a developing device that forms a visible image using, the apparent permeability of the two-component developer is detected, and based on a comparison result between a detection signal value and a predetermined reference signal value, A reference signal value correcting unit that corrects a reference signal value based on the operation time or the number of operations of the developing device and resets the reference signal value as a new reference signal value. And an error detection means for displaying an error when the detection signal value exceeds a predetermined upper limit value or lower limit value and stopping an image forming operation, wherein the predetermined upper limit value or lower limit value is defined as the reference signal value. An image forming apparatus that performs correction in conjunction is disclosed.

Further, Patent Document 2 provides a control device that stably controls image density with an inexpensive apparatus configuration that eliminates toner density sensor adjustment means while using both a toner density sensor and a pattern density sensor. Is a toner density control device developed for the purpose of detecting the developer density from the magnetic permeability of the developer in the developing device and the density of the reference pattern imaged on the photoconductor. A pattern density sensor is provided. During normal operation, a toner replenishment amount is determined from the difference between the output of the toner density sensor and a reference value, and a reference pattern is created on the photosensitive member at a predetermined timing, and the density is set in the pattern. In a toner concentration control device configured to detect with a density sensor and correct the reference value according to the detection result, the developing device is driven immediately after the replacement of the developer, and the toner concentration sensor The output is detected, the upper limit value (VrefH) and the lower limit value (VrefL) of the reference value (Vref) are determined based on the output value (Vti), and until the next developer replacement, the pattern density sensor There is disclosed a toner density control device in which the reference value is corrected in the range of VrefH to VrefL based on the detection result.

JP 2003-57939 A Japanese Patent No. 3451470

However, in the above-described prior art, for example, when the cleaning device and the developing device are used as an integrated cartridge, for example, when the developing device is once removed from the image forming apparatus main body and reattached with the life of the cleaning device. For example, when the toner density in the developer is different from the previous one, if the initial setting is performed, the target limiter position of the toner density sensor is shifted.
FIG. 4 is an explanatory diagram showing such a problem of the prior art. In FIG. 4, for example, after the control signal (Vcnt) is once stored in the toner density sensor, a developing device in which the control signal (Vcnt) is stored is installed in another machine such as a series machine having different linear speeds. When used, there is a problem that the relationship between the toner density (TC) and the sensor output (Vt) is shifted. Specifically, when the toner density sensor adjusted for Vcnt with the linear speed of 150 mm / sec for # 27 and 28 is reused with the linear speed of 200 mm / sec for # 26, the relationship of TC-Vt is shown in FIG. , Shifted in the direction of the arrow, that is, diagonally upward to the right.

The present invention has been made in view of the above-described problems of the prior art, and the problem is that even when the image is remounted on another image forming apparatus and used again, the intended toner concentration is achieved. It is an object of the present invention to provide a toner density control device that can be used without shifting the limiter position of a sensor, and to provide a developing device and an image forming apparatus including the toner density control device, and a toner density control method using the same.

In order to solve the above problems, a toner density control device according to the present invention is detachably provided to an image carrier and an image forming apparatus main body, holds a developer, and supplies toner to the image carrier. A two-component developing device, a toner concentration sensor that is attached to the two-component developing device and detects a toner concentration in the developer, and a control signal (Vcnt) value input to the toner concentration sensor is changed. Control means for adjusting an output signal (Vt) of the toner density sensor, a toner supply apparatus for supplying toner to the two-component developing device, and a toner density in the developer based on an output value of the toner density sensor And a reference value (Vref) having an upper limit value (VrefH) and a lower limit value (VrefL) for the output value of the toner density sensor. Based on the difference between the output value of the toner density sensor and the reference value, the toner supply amount to the developing device is determined, and the reference value is corrected within a range between the upper limit value and the lower limit value for a certain period. In the toner density control device applied to the image forming apparatus, the control signal value adjustment mode on / off storage device and the control signal (Vcnt) value provided in the two-component developing device or the toner density sensor are provided. A control signal storage device for storing the control signal, storing the control signal after the change in the control signal storage device, and adjusting the output signal of the toner density sensor based on the stored control signal after the change The toner supply amount to the developing device is determined based on the difference between the adjusted output value of the toner density sensor and the reference value, and the control signal value adjustment mode on / off storage device When the adjustment mode on is selected, the control signal (Vcnt) input to the toner density sensor is changed and adjusted after resetting the two-component developing device to another image forming device. It is characterized by that.
In this case, a storage device for storing the value of the linear velocity of the image carrier is provided, and when the developing device is reused between image forming apparatuses having image carriers of different linear velocity, a plurality of linear velocities are obtained. Correspondingly, it is preferable that the control signal (Vcnt) value is adjusted, and a control signal value corresponding to the linear velocity of the image carrier at the time of reuse is determined based on these control signal values.
Further, a storage device for storing the linear velocity value of the image carrier is provided, and when the developing device is reused between image forming apparatuses having image bearing members of different linear velocities, the developing device or the toner density sensor A storage device for storing the linear velocity of the image carrier when the control signal (Vcnt) value is adjusted, and an image carrier having a linear velocity different from the linear velocity for which the control signal (Vcnt) adjustment is performed. When the developing device is used in the image forming apparatus, the control signal (Vcnt) determined in advance according to the linear velocity of the image carrier may be corrected.
Further, when the developing device is reused between image forming apparatuses having image bearing members with different linear velocities, after the developing device is set in another image forming apparatus, the linear speed is shared between the image forming apparatuses. The corresponding control signal (Vcnt) may be adjusted, and the control signal value may be stored in the control signal (Vcnt) storage device.

Further, when the developing device is reused between image forming apparatuses having image bearing members of different linear speeds, the developing apparatus is re-used with an image forming apparatus having a linear speed different from that of the image forming apparatus in which the control signal (Vcnt) is adjusted. When used, the lower limit value (VrefL) and / or the upper limit value (VrefH) of the reference value of the output value of the toner density sensor may be corrected.
Further, when the toner density sensor output signal (Vt) / linear velocity storage device is provided and the developing device is reused in an image forming device having a linear velocity different from that of the image forming device in which the control signal (Vcnt) is adjusted, Vt The Vt / line speed is measured and stored in the Vt / line speed storage device, and the lower limit value (VrefL) and / or the upper limit value (VrefH) of the reference value of the output value of the toner density sensor is stored in the Vt / line. It is good also as what correct | amends based on the relationship of speed.
Furthermore, when the developing device is reused between image forming apparatuses having image bearing members with different linear velocities, the developing device is used with an image forming apparatus having a linear velocity different from that of the image forming apparatus having the control signal (Vcnt) adjusted. In the case of reuse, the output value (Vt) of the toner density sensor may be corrected by a certain amount.
Furthermore, when the output signal (Vt) / linear velocity storage device of the toner density sensor is provided and the developing device is reused in an image forming device having a different linear velocity from the image forming device in which the control signal (Vcnt) is adjusted, The relationship between Vt / linear velocity is measured, stored in the Vt / linear velocity storage device, and the output value (Vt) of the toner density sensor is corrected by a fixed amount based on the stored relationship of Vt / linear velocity. Good.

The developing device according to the present invention is detachably provided to the image carrier and the image forming apparatus main body, holds a developer, and supplies toner to the image carrier, and the two-component developer. A toner density sensor attached to the developing device for detecting the toner density in the developer and an output signal (Vt) of the toner density sensor by changing a control signal (Vcnt) value input to the toner density sensor. Control means for adjusting the toner, a toner replenishing device for replenishing toner to the two-component developing device, and a toner concentration control device for controlling the toner concentration in the developer based on the output value of the toner concentration sensor. A reference value (Vref) having an upper limit value (VrefH) and a lower limit value (VrefL) with respect to the output value of the toner density sensor is provided. Applied to an image forming apparatus that determines a toner replenishment amount based on a difference from a reference value and corrects the reference value within a range between the upper limit value and the lower limit value for a certain period. The developing device, comprising: the toner density sensor; the detection signal control means; and the toner density control device, wherein the toner density control device is defined in any one of claims 1 to 8. The toner density control device described above is characterized.

The image forming apparatus according to the present invention is provided with an image carrier, a two-component developing device that is detachably attached to the image forming apparatus main body, holds a developer, and supplies toner to the image carrier; A toner density sensor attached to the component developing device for detecting the toner density in the developer and an output signal (Vt) of the toner density sensor by changing a control signal (Vcnt) value input to the toner density sensor. ), A toner replenishing device for replenishing toner to the two-component developing device, and a toner concentration control device for controlling the toner concentration in the developer based on the output value of the toner concentration sensor. A reference value (Vref) having an upper limit value (VrefH) and a lower limit value (VrefL) is provided for the output value of the toner density sensor, and the output value of the toner density sensor is In the image forming apparatus, a toner replenishment amount to the developing device is determined based on a difference from the reference value, and the reference value is corrected within a range between the upper limit value and the lower limit value for a certain period. The toner concentration control device is a toner concentration control device according to any one of claims 1 to 8.

A toner density control method according to the present invention includes an image carrier, a two-component developing device that is detachably attached to the image forming apparatus main body, holds a developer, and supplies toner to the image carrier; A toner density sensor attached to the two-component developing device for detecting the toner density in the developer, and an output signal (Vcnt) value input to the toner density sensor by changing the value of the control signal (Vcnt). Vt), a toner supply device that supplies toner to the two-component developing device, a toner concentration control device that controls the toner concentration in the developer based on the output value of the toner concentration sensor, Control signal value adjustment mode on / off storage device provided in the two-component developing device or the toner density sensor, and control signal storage for storing the control signal (Vcnt) value A toner density control method in the developing device in the image forming apparatus, wherein the control signal (Vcnt) storage device provided in the two-component developing device or the toner density sensor is changed or adjusted. The control signal is stored, the output signal of the toner density sensor is adjusted based on the stored control signal, and the output value, the upper limit value (VrefH) and the lower limit value (VrefL) of the adjusted toner density sensor are obtained. A difference between the reference value (Vref) and the toner supply amount to the developing device is determined based on the difference, and the reference value is corrected within a range between the upper limit value and the lower limit value for a certain period. When the control signal value adjustment mode on / off storage device selects the adjustment mode on, the two-component developing device is reset to another image forming device, Serial changes the control signal inputted to the toner density sensor (Vcnt), characterized in that so as to adjust.

According to the toner concentration control device of the present invention, only when the control signal (Vcnt) adjustment mode on is selected, the developing device is set in another image forming apparatus, for example, after the main power source is turned on, Since the Vcnt adjustment is performed, even when the developing device is reattached to another image forming apparatus and used again, the position of the limiter of the toner density sensor to be applied is prevented, and a good toner can be prevented. Concentration control can be realized.
According to the developing device of the present invention, even when the developing device is reinserted into another image forming apparatus main body and used again, the toner density sensor can be prevented from being displaced and good toner density control can be performed. It can be carried out.
According to the image forming apparatus of the present invention, it is possible to form a high-quality image by good toner density control while preventing the position shift of the limiter of the toner density sensor.
According to the toner density control method of the present invention, even when the developing device is reattached to another image forming apparatus and used again, the limiter position of the toner density sensor to be originally applied is prevented from being shifted, Good toner density control can be realized.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 5 is an explanatory diagram showing a main part of an image forming apparatus including a two-component developing device to which the toner density control device of the present invention is applied. 5, the image forming apparatus includes a photoconductor 10 as an image carrier, a charging device 20 disposed around the photoconductor 10, an exposure device (30) not shown, a developing device 40, a transfer device 50, and the like. The cleaning device 60 is mainly configured.
This image forming apparatus includes a sheet feeding / conveying device (not shown) that feeds transfer paper on a paper feeding tray (not shown) to the transfer device 50, and a transfer paper on which a toner image has been transferred is separated from the photoconductor 10. A fixing device (not shown) for fixing the toner image to the transfer paper is provided.

The developing device 40 includes a developing sleeve 41 that is disposed adjacent to the photoreceptor 10 and carries a two-component developer (hereinafter simply referred to as a developer) containing toner and a magnetic carrier on the surface. The developing sleeve 41 is disposed in the developing casing 42 in the vicinity of the photoreceptor 10 and is attached so that a part thereof is exposed from the casing opening. The developing sleeve 41 is driven by a driving device (not shown). Inside the developing sleeve 41, a magnet roller (not shown) composed of a fixed magnet group as a magnetic field generating means is fixed and arranged. The developing device 40 includes a doctor 43 as a developer regulating member made of a rigid body that regulates the amount of developer carried on the developing sleeve 41. A developer accommodating portion 44 that accommodates the developer is formed on the upstream side of the rotation direction of the developing sleeve 41 with respect to the doctor 43, and the first and second developer agitating and mixing the developer in the developer accommodating portion 44. Agitation screws 45 and 46 are provided. A toner concentration sensor 47 for detecting the toner concentration is disposed at the bottom of the developer accommodating portion 44.
Above the developer accommodating portion 44, a toner replenishing port (not shown), a toner cartridge 48 filled with toner to be replenished to the developer accommodating portion, and a toner flow for connecting the toner replenishing port and the toner cartridge are connected. Device.

In the image forming apparatus having such a configuration, for example, the surface of the rotating photosensitive member 10 is uniformly charged by the charging device 20, and then the photosensitive member is irradiated with, for example, a laser beam from the exposure device (30) based on the image information. A latent image formation is formed on 10. The toner charged by the developing device 40 is supplied to the electrostatic latent image formed on the photoconductor 10 to form a toner image. That is, in the developing device 40, when the first and second stirring screws 45 and 46 are rotated, the developer in the developer containing portion 44 is stirred, and the toner and the magnetic carrier are triboelectrically charged in opposite polarities. To do. The developer in which the toner and the magnetic carrier are charged with opposite polarities is supplied and carried on the circumferential surface of the developing sleeve 41 that is rotationally driven, and is conveyed in the rotational direction by the rotation of the developing sleeve 41. The amount of the conveyed developer is regulated by the doctor 43, and the regulated developer is conveyed to a development area where the photoconductor 10 and the developing sleeve 41 face each other. The toner in the developer carried to the development area is electrostatically transferred to the electrostatic latent image on the surface of the photoreceptor, and the electrostatic latent image is visualized to form a toner image.
On the other hand, the transfer paper on the paper feed tray is transported to a transfer section where the photoconductor 10 and the transfer device 50 face each other by a paper transport device (not shown). Here, the transfer device 50 transfers the photoconductor to the transfer paper. A charge having a polarity opposite to that of the toner image on the toner 10 is applied, whereby the toner image formed on the photoconductor 10 is transferred to transfer paper. The transfer paper onto which the toner image has been transferred is separated from the photoreceptor 10 and sent to a fixing device (not shown) to fix the toner image on the transfer paper, thereby forming a fixed image.

In an image forming apparatus such as a copier or printer, in order to maintain the image density, a test pattern of toner is created outside the printing area, and the amount of adhesion of the image is detected by detecting the amount of adhesion of the pattern. The formation conditions are controlled. In particular, in a full-color machine, in order to maintain density gradation and color reproducibility, for example, an adhesion amount from a high density part to a low density part is detected. When detecting the adhesion amount from the high density portion to the low density portion, for example, a plurality of toner image patterns are created in order to obtain gradation. As a method of creating a plurality of toner image patterns, for example, an image is formed by changing the developing bias and exposure energy in the rotation direction on the image carrier, and when the toner image pattern reaches the position of the density sensor, the density is sequentially detected. However, since the detection time becomes longer, frequent detection cannot be performed, and the detection is performed at predetermined time intervals or at predetermined print sheet intervals.

Below, the characteristic part of this invention is demonstrated in detail.
FIG. 6 is a block diagram showing a configuration of a toner concentration sensor applied to the toner concentration control apparatus according to the embodiment of the invention. In FIG. 6, for example, a RAM is provided in the main body of the image forming apparatus. A control signal (Vcnt) storage device, a control signal (Vcnt) adjustment mode on / off storage device, and a Vpnt adjustment Vp storage device are included in the developing device. The toner density sensor is provided.
The operation of the toner concentration control apparatus according to the embodiment of the present invention having such a toner concentration sensor will be described below.

Example 1
FIG. 1 is a flowchart showing a control signal (Vcnt) adjustment operation in the toner concentration control apparatus according to the present embodiment.
In FIG. 1, the control signal (Vcnt) adjustment operation corresponds to, for example, the invention according to claim 1 and is performed as follows.
That is, first, the main power supply of the image forming apparatus is turned on (step S1), then the motors are started (step S2), the OPC and the developing device are rotated, and the fluidity of the developer is stabilized, thereby The detection signal (Vt) is stabilized. The control signal (Vcnt) at this time is set to Vcnt1 (step S3). Next, the Vcnt adjustment mode is turned on, and a Vcnt adjustment on / off signal stored in a Vcnt adjustment on / off storage device provided in a toner density sensor (hereinafter also referred to as an HST sensor) of the developing device is read (step) S4).
Next, Vcnt1 is set to the upper limit value of Vcnt, for example, 5.0 V, Vcnt1 is decreased by 0.1 V as necessary (step S5), and then the toner density sensor output Vt1 at Vcnt1 is detected (step S6). ). Next, the detected Vt1 is stored in the RAM (step S7).
It is determined whether or not Vt1 is within a target value range of, for example, 3.0V ± 0.2V (step S8). If not, return to step 5 to decrease Vcnt1 by 0.1v. (Step S5). After Vcnt1 is reduced by 0.1 v, Vt1 is detected (step S6), and the detection signal Vt1 is stored in, for example, the RAM of the main body (step S7). It is determined whether the voltage is within ± 0.2 V (step S8). This operation is repeated until Vt1 enters the target value, for example, 3.0V ± 0.2V. When Vt1 enters the target value, it is determined that Vcnt adjustment is completed, and Vcnt1 is set to Vcnt0 (step S9). This value is stored in a memory (Vcnt storage device) provided in the HST sensor (step S10), and toner density control during normal printing is performed using this control signal Vcnt value. Thereafter, the motors are stopped and the Vcnt adjustment is finished (step S11).
The toner density is controlled as follows, for example.
That is, the Vcnt is stored in a control signal (Vcnt) storage device, the output signal of the toner density sensor is adjusted based on the stored control signal, the adjusted output value of the toner density sensor and the upper limit value (VrefH). ) And a reference value (Vref) having a lower limit value (VrefL), and a toner replenishment amount to the developing device is determined based on the difference. At this time, the reference value is corrected within the range between the upper limit value and the lower limit value for a certain period, and when the control signal value adjustment mode on / off storage device selects the adjustment mode on, the 2 After resetting the component developing device to another image forming apparatus, the control signal (Vcnt) input to the toner density sensor is changed and adjusted.

Example 2
Next, a second embodiment of the present invention will be described. FIG. 2 is a flowchart showing another control signal (Vcnt) adjustment operation in the toner concentration control apparatus according to the present embodiment. This embodiment corresponds to the invention according to claim 2, for example.
In FIG. 2, first, the main power supply of the image forming apparatus is turned on (step S21). Next, after the linear velocity of the image carrier is set to, for example, the faster value Vp2 (200 mm / sec) (step S22), adjustment from (step S2) to (step S10) in FIG. 1 is performed (step S23). ), Vcnt1 is set to Vcnt2 (step S24), and stored in the RAM of the main body (step S25). Next, after the linear velocity of the image carrier is set to, for example, the slower value Vp2 (150 mm / sec) (step S26), the adjustment from (step S2) to (step S10) in FIG. 1 is performed (step S27). ), Vcnt1 is set to Vcnt3 (step S28), and Vcnt3 is stored in the RAM of the main body (step S29).
Next, the inclination of Vcnt with respect to the linear velocity is calculated from Vcnt / Vp: Vcnt2, Vcnt3, Vp2, and Vp3 (step S30), and Vcnt / Vp is stored in the RAM of the main body (step S31). Next, the linear velocity Vp1 (150 mm / sec in this embodiment), which is the center of the machine that has performed Vcnt adjustment, is stored in the memory of the HST sensor (step S32), and Vcnt adjustment is terminated.

Example 3
FIG. 3 is a flowchart showing another control signal (Vcnt) adjustment operation.
When the developing device is used by replacing it with a machine body of another linear speed, the relationship of TC-Vt is shifted if Vcnt0 is used as it is.
Accordingly, when the developing device is used in a machine b (Vpb) different from the machine a (linear speed Vpa) adjusted in Vcnt in FIGS. 1 and 2, the center linear speed of the machine (175 mm / sec in this embodiment). The Vcnt used in is determined by the following operation.
That is, the control signal Vcnt0 ′ at the machine b is corrected to the control signal Vcnt0 adjusted at the machine a before replacement, and Vcnt0 ′ = [Vcnt0 adjusted at the machine a before replacement] + Vcnt / Vp * (Vpa−Vpb ) (Step 35). In the invention according to claim 3, Vcnt / Vt in FIG. 3 is a fixed value.
According to the second and third embodiments, in the toner density control apparatus according to the first embodiment, the main body includes a storage device that stores the value of the linear velocity, and the developing unit is reused between image forming apparatuses having different linear velocities. Since the Vcnt value is adjusted at a plurality of linear velocities and the Vcnt value of the linear velocities is determined based on the Vcnt values, the Vcnt is temporarily stored in the toner density sensor as in the first embodiment. In this case, even if a developing device that stores Vcnt in a machine having a different linear speed such as a series machine is reused, the relationship between TC and Vt can be used without deviation.

Example 4
This embodiment corresponds to, for example, the invention of claim 4 and, as shown in Table 1, series machines each having three line speeds (high line speed, medium line speed, and low line speed) ( For example, in the case of machine a, machine b, machine c), the linear speed for Vcnt adjustment is the common linear speed of each series (in this embodiment, a low linear speed of 100 mm / sec), and the control signal (Vcnt ) Adjustment is performed, and the Vcnt adjustment value is stored in the memory of the HST sensor. It should be noted that even if the linear speeds are not exactly the same, for example, a case where there is only a deviation that does not cause a problem of the relationship of Vcnt−Vt at a linear speed of about ± 10% is naturally considered within the scope of the present invention.

By doing so, for example, even if the Vcnt adjustment is performed on the series machine a and the developing device is reused on the series machine b or c as it is, the Vcnt adjustment is performed at the same linear speed. The relationship will not shift.
According to the fourth embodiment, in the toner concentration control apparatus according to the first embodiment in which the developing device (hereinafter also referred to as a developing unit) is reused in the series machines having different linear speeds, the linear speed that the series machines have in common. Since the Vcnt adjustment after replacement of the developing device is performed and the value is stored in the Vcnt storage device, for example, the Vcnt adjustment is performed on the series machine a and the developing device is re-adjusted on the series machine b or c. Even if it is used, since the Vcnt adjustment is performed at the same linear velocity, the TC-Vt relationship does not deviate.
Conventionally, when TC-Vt fluctuates due to different linear speeds in each machine, VrefL and VrefH are shifted according to the linear speed of each machine, and Vcnt is shifted by a certain value. A method such as shifting Vt by a certain value has been adopted.

Example 5
Next, Embodiment 5 of the present invention will be described with reference to FIG.
Example 5 is, for example, the example of FIGS. 1 and 2. For example, when the “center linear velocity” of the aircraft a is set to a high linear velocity (250 mm / sec) and Vcnt adjustment is performed at this linear velocity, the linear velocity Vp1 Is stored in the memory of the HST sensor, and the developing unit used at this time is reused by the machine b (the center line speed is, for example, 225 mm / sec).
That is, after the main power source of the image forming apparatus is turned on (step S41), the motors are started (step S42), and then the developing device used in the machine a is set in the machine b. The linear velocity (Vp1) of machine a stored in the sensor memory is read (step S43). Next, it is determined whether or not the Vp1 value is equal to the linear velocity (Vp2) of the aircraft b (step S44). If they are different, the target lower limit value VrefL and upper limit value VrefH of the toner density are set to the linear velocity. Is corrected based on the Vt shift amount (fixed value const) determined by (step S45, S46). By doing this, for example, even if the control signal (Vcnt) is adjusted in the series machine a and the developing device is reused in the series machine b or c, the VrefL or VrefH is corrected by the difference in the linear speed. Therefore, the aim of the upper and lower limits of the toner density does not shift. Thereafter, the motors are stopped (step S47), and the adjustment of the control signal Vcnt is ended.
According to the fifth exemplary embodiment, in the toner density control apparatus according to the first exemplary embodiment in which the developing unit is reused in an image forming apparatus having a different linear velocity, the developing device is reused in a machine having a linear velocity different from that of the machine having the Vcnt adjustment. In this case, since the reference value VrefL and / or the upper limit value VrefH of the output value of the toner density sensor is corrected to a constant value, for example, Vcnt adjustment is performed on the series machine a and the developing device is used as it is. Even if it is reused, the toner density can be controlled without deviating from the linear velocity.
Conventionally, when TC-Vt fluctuates with different linear speeds in each machine, VrefL and VrefH are shifted according to the linear speed of each machine, Vcnt is shifted by a certain value, Vt A method such as shifting the value by a certain value has been adopted.

Example 6
Next, Embodiment 6 of the present invention will be described with reference to FIG.
Example 6 is an example of FIGS. 1 and 2, for example, after the Vcnt adjustment is completed assuming that the machine a has three types of linear speeds as shown in Table 1, and the Vcnt fixed value (for example, Vcnt1) remains. Vp1 and Vp2 (for example, high linear velocity 250 mm / sec and medium linear velocity 225 mm / sec) are detected, and the outputs Vp1 and Vp2 of the respective HST sensors are detected, and ΔVt / ΔVp is determined based on these values. This is calculated (step S58) and stored in the memory of the HST sensor (step S59).
When this developing unit is reused in the machine b, Vt / ΔVp calculated here is used for “const” in steps 45 and 46 of FIG.
By doing this, for example, even if the control signal (Vcnt) is adjusted on the series machine a and the developing device is reused on the series machine b or c as it is, the VrefL or VrefH is corrected by the difference in the linear speed. Therefore, the aim of the upper and lower limits of the toner density does not shift, and even when the relationship between the linear velocity and Vt is shifted due to some variation in the mounting position of the HST sensor to the developing device, the toner density control can be performed with high accuracy. can do.
According to the sixth embodiment, when the developing device is reused on a machine with a different linear speed from the machine on which Vcnt adjustment is performed, the relationship between Vt / linear speed is measured and stored in the “Vt / linear speed” storage device of the toner density sensor. Since the lower limit value VrefL and / or the upper limit value VrefH of the reference value of the output value of the toner density sensor is corrected to a constant value, for example, the mounting position of the toner density sensor on the developing device varies somewhat and the linear velocity Even when the relationship of Vt is shifted, the toner density can be controlled with high accuracy.
Conventionally, when TC-Vt fluctuates due to different linear speeds in each machine, VrefL and VrefH are shifted according to the linear speed of each machine, and Vcnt is shifted by a certain value. A method such as shifting Vt by a certain value has been adopted.

Example 7
Next, a seventh embodiment of the present invention will be described with reference to FIG.
The embodiment 7 is, for example, the embodiment of FIGS. 1 and 2. For example, when the center line speed of the aircraft a is set to a high line speed (250 mm / sec) and the control signal (Vcnt) is adjusted at this line speed, The value of the speed Vp1 is stored in the memory of the HST sensor, and the developing unit used in the machine a is used in the machine b.
That is, the determination of the Vt shift amount ΔVt is performed as follows. First, after the main power supply of the image forming apparatus is turned on (step 71), the motors are started (step S72), and then the developing unit used in the machine a is set to the machine b (the center linear velocity is, for example, 225 mm / sec). ) And read Vp1 stored in the memory of the HST sensor (step S73). Next, it is determined whether or not Vp1 is the same as the value of the linear velocity (Vp0) of the aircraft b (step 75). If different, the output value Vt of the HST sensor is corrected for Vt by the linear velocity ΔVt ( Step 76). At this time, the correction corrects a predetermined value (const: Vt usually varies substantially linearly with respect to the linear velocity as shown in FIG. 7) with respect to the change of the linear velocity. FIG. 7 is a diagram showing the relationship between the linear velocity and the Vt shift. Thereafter, the motors are stopped (step 77). By doing this, for example, even if the Vcnt adjustment is performed on the series machine a and the developing device is reused on the series machine b or c as it is, the Vt is corrected by the difference in the linear speed, so the toner density control Will not slip.
According to the seventh embodiment, in the toner density control apparatus according to the first embodiment in which the developing unit is reused in the image forming apparatus having a different linear velocity, the developing device is reused in a machine having a different linear velocity from the machine having the Vcnt adjustment. In this case, since the output value Vt of the toner density sensor is corrected by a certain amount,
For example, even if the Vcnt adjustment is performed on the series machine “a” and the developing device is reused on the series machine “b” or “c” as it is, the toner density control can be controlled without shifting by the linear velocity.
Conventionally, when TC-Vt fluctuates due to different linear speeds in each machine, VrefL and VrefH are shifted according to the linear speed of each machine, and Vcnt is shifted by a certain value. A method such as shifting Vt by a certain value has been adopted.

Example 8
Next, an eighth embodiment of the present invention will be described with reference to FIG. 9 described above.
Example 8 is an example of FIGS. 1 and 2, for example, and after the Vcnt adjustment is finished assuming that the machine a has three types of linear speeds as shown in Table 1, the Vcnt fixed value (for example, Vcnt1) remains unchanged. Vp1 and Vp2 (for example, high linear velocity 250 mm / sec and medium linear velocity 225 mm / sec) are detected, and the outputs Vp1 and Vp2 of the respective HST sensors are detected, and ΔVt / ΔVp is determined based on these values. The calculation is performed (step 58) and stored in the memory of the HST sensor (step 59). Here, when the developing unit used in the machine a is reused in the machine b, FIG. Vt / ΔVp calculated here is used for “const”.
By doing this, for example, even if the control signal (Vcnt) is adjusted in the series machine a and the developing device is reused as it is in the series machine b or c, the Vt is corrected by the difference in the linear speed. Therefore, the toner density control does not shift. Further, even when the position where the HST sensor is attached to the developing device varies somewhat and the relationship between the linear velocity and Vt shifts, the toner density can be controlled with high accuracy.
According to the eighth embodiment, when the developing device is reused on a machine having a different linear speed from the machine on which Vcnt adjustment is performed, the relationship between Vt / linear speed is measured and stored in the “Vt / linear speed” storage device of the toner density sensor. Since the output value Vt of the toner density sensor is corrected by a certain amount, for example, even when the relationship between the linear speed and Vt is shifted due to a slight variation in the mounting position of the toner density sensor to the developing device, it is accurate. The toner density can be controlled.
Conventionally, when TC-Vt fluctuates due to different linear speeds in each machine, VrefL and VrefH are shifted according to the linear speed of each machine, and Vcnt is shifted by a certain value. A method such as shifting Vt by a certain value has been adopted.

6 is a flowchart illustrating an example of a control signal (Vcnt) adjustment operation in the toner density control device. 10 is a flowchart showing another control signal (Vcnt) adjustment operation in the toner density control device. It is a flowchart which shows the principal part of another control signal (Vcnt) adjustment operation. It is explanatory drawing which shows the problem of a prior art. FIG. 2 is an explanatory diagram illustrating a main part of the developing device and the image forming apparatus of the present invention. FIG. 3 is a block diagram illustrating a configuration of a toner concentration sensor applied to the present invention. It is a figure which shows the relationship between a sensor output (Vt) and a linear velocity. Furthermore, it is a flowchart which shows the control signal adjustment operation | movement which is another Example. Furthermore, it is a flowchart which shows the control signal adjustment operation | movement which is another Example. Furthermore, it is a flowchart which shows the control signal adjustment operation | movement which is another Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image carrier 20 Charging device 30 Exposure device 40 Developing device 41 Developing sleeve 42 Developing casing 43 Doctor 44 Developer container 45 Stirring screw 46 Stirring screw 47 Toner density sensor 48 Toner cartridge 50 Transfer device 60 Cleaning device

Claims (11)

An image carrier;
A two-component developing device that is detachably attached to the image forming apparatus main body, holds a developer, and supplies toner to the image carrier;
A toner concentration sensor attached to the two-component developing device for detecting a toner concentration in the developer;
Control means for adjusting an output signal (Vt) of the toner density sensor by changing a control signal (Vcnt) value input to the toner density sensor;
A toner supply device for supplying toner to the two-component developing device;
A toner concentration control device for controlling the toner concentration in the developer based on the output value of the toner concentration sensor,
A reference value (Vref) having an upper limit value (VrefH) and a lower limit value (VrefL) is provided for the output value of the toner density sensor,
Determining a toner replenishment amount to the developing device based on a difference between the output value of the toner density sensor and the reference value;
In the toner density control device applied to the image forming apparatus in which the correction of the reference value is performed within a range between the upper limit value and the lower limit value for a certain period of time,
A control signal value adjustment mode on / off storage device provided in the two-component developing device or the toner density sensor, and a control signal storage device for storing the control signal (Vcnt) value;
The control signal storage device stores the changed control signal,
The output signal of the toner density sensor is adjusted based on the stored changed control signal, and the amount of toner replenished to the developing device based on the difference between the adjusted output value of the toner density sensor and the reference value Decide
When the control signal value adjustment mode on / off storage device selects the adjustment mode on, the two-component developing device is reset to another image forming apparatus and then input to the toner density sensor. A toner density control device characterized in that a control signal (Vcnt) is changed and adjusted. In the toner concentration control device according to claim 1,
A storage device for storing a linear velocity value of the image carrier;
When reusing the developing device between image forming apparatuses having image bearing members of different linear velocities,
The control signal (Vcnt) value is adjusted corresponding to a plurality of linear velocities, and a control signal value corresponding to the linear velocity of the image carrier at the time of reuse is determined based on these control signal values. A toner concentration control device. In the toner concentration control device according to claim 1,
A storage device for storing a linear velocity value of the image carrier;
When reusing the developing device between image forming apparatuses having image bearing members of different linear velocities,
The developing device or the toner density sensor includes a storage device that stores a linear velocity of the image carrier when the control signal (Vcnt) value is adjusted,
When the developing device is used in an image forming apparatus having an image carrier having a linear velocity different from the linear velocity for which the control signal (Vcnt) is adjusted, a control signal (determined in advance according to the linear velocity of the image carrier) Vcnt) is corrected. In the toner concentration control device according to claim 1,
When reusing the developing device between image forming apparatuses having image bearing members of different linear velocities,
After setting the developing device in another image forming apparatus,
Adjusting the control signal (Vcnt) corresponding to a common linear velocity between the image forming apparatuses;
A toner concentration control device, wherein the control signal value is stored in the control signal (Vcnt) storage device. In the toner concentration control device according to claim 1,
When reusing the developing device between image forming apparatuses having image bearing members of different linear velocities,
When the developing device is reused in an image forming apparatus having a linear velocity different from that of the image forming apparatus in which the control signal (Vcnt) is adjusted, the lower limit value (VrefL) and / or the upper limit value of the reference value of the output value of the toner density sensor ( VrefH) is corrected, and the toner density control device is characterized in that: The toner concentration control apparatus according to claim 5,
An output signal (Vt) / linear velocity storage device of the toner density sensor is provided;
When the developing device is reused in an image forming apparatus having a linear velocity different from that of the image forming apparatus in which the control signal (Vcnt) is adjusted,
Measure the relationship of Vt / linear velocity, store it in the Vt / linear velocity storage device,
A toner concentration control apparatus, wherein a lower limit value (VrefL) and / or an upper limit value (VrefH) of a reference value of an output value of a toner density sensor is corrected based on the stored Vt / linear velocity relationship. The image forming apparatus according to claim 1.
When reusing the developing device between image forming apparatuses having image bearing members of different linear velocities,
When the developing device is reused in an image forming apparatus having a linear velocity different from that of the image forming apparatus in which the control signal (Vcnt) is adjusted, the toner density sensor is characterized by correcting the output value (Vt) by a certain amount. Control device. The image forming apparatus according to claim 7.
An output signal (Vt) / linear velocity storage device of the toner density sensor is provided;
When the developing device is reused in an image forming apparatus having a linear velocity different from that of the image forming apparatus in which the control signal (Vcnt) is adjusted,
Measure the relationship of Vt / linear velocity, store it in the Vt / linear velocity storage device,
A toner density control apparatus, wherein an output value (Vt) of a toner density sensor is corrected by a fixed amount based on the stored Vt / linear velocity relationship. An image carrier;
A two-component developing device that is detachably attached to the image forming apparatus main body, holds a developer, and supplies toner to the image carrier;
A toner concentration sensor attached to the two-component developing device for detecting a toner concentration in the developer;
Control means for adjusting an output signal (Vt) of the toner density sensor by changing a control signal (Vcnt) value input to the toner density sensor;
A toner supply device for supplying toner to the two-component developing device;
A toner concentration control device for controlling the toner concentration in the developer based on the output value of the toner concentration sensor,
A reference value (Vref) having an upper limit value (VrefH) and a lower limit value (VrefL) is provided for the output value of the toner density sensor,
Determining a toner replenishment amount to the developing device based on a difference between the output value of the toner density sensor and the reference value;
The developing device applied to an image forming apparatus in which the correction of the reference value is performed within a range between the upper limit value and the lower limit value for a certain period,
The toner density sensor, the detection signal control means, and the toner density control device;
The developing device according to claim 1, wherein the toner concentration control device is the toner concentration control device according to claim 1. An image carrier;
A two-component developing device that is detachably attached to the image forming apparatus main body, holds a developer, and supplies toner to the image carrier;
A toner concentration sensor attached to the two-component developing device for detecting a toner concentration in the developer;
Control means for adjusting an output signal (Vt) of the toner density sensor by changing a control signal (Vcnt) value input to the toner density sensor;
A toner supply device for supplying toner to the two-component developing device;
A toner concentration control device for controlling the toner concentration in the developer based on the output value of the toner concentration sensor,
A reference value (Vref) having an upper limit value (VrefH) and a lower limit value (VrefL) is provided for the output value of the toner density sensor,
Determining a toner replenishment amount to the developing device based on a difference between the output value of the toner density sensor and the reference value;
In the image forming apparatus in which the reference value is corrected within a range between the upper limit value and the lower limit value for a certain period of time,
The image forming apparatus according to claim 1, wherein the toner density control device is the toner density control device according to claim 1. An image carrier;
A two-component developing device that is detachably attached to the image forming apparatus main body, holds a developer, and supplies toner to the image carrier;
A toner concentration sensor attached to the two-component developing device for detecting a toner concentration in the developer;
Control means for adjusting an output signal (Vt) of the toner density sensor by changing a control signal (Vcnt) value input to the toner density sensor;
A toner supply device for supplying toner to the two-component developing device;
A toner concentration control device for controlling the toner concentration in the developer based on the output value of the toner concentration sensor;
The development in an image forming apparatus comprising: a control signal value adjustment mode on / off storage device provided in the two-component developing device or the toner density sensor; and a control signal storage device that stores the control signal (Vcnt) value. A toner concentration control method in the apparatus,
Storing the changed or adjusted control signal in the control signal (Vcnt) storage device provided in the two-component developing device or the toner density sensor;
Based on the stored control signal, the output signal of the toner density sensor is adjusted, and the adjusted output value of the toner density sensor and a reference value (Vref) having an upper limit value (VrefH) and a lower limit value (VrefL). A difference is obtained, and a toner replenishment amount to the developing device is determined based on the difference, and the reference value is corrected within a range between the upper limit value and the lower limit value for a certain period, and the control signal value adjustment is performed. When the mode on / off storage device selects the adjustment mode on, the control signal (Vcnt) input to the toner density sensor after the two-component developing device is reset to another image forming device. A toner density control method characterized in that the toner density is changed and adjusted.

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