JP2003066710A - Image forming device, its control method and process unit for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device switching and using an inductance detection ATR and a video count ATR and capable of maintaining appropriate toner concentration. SOLUTION: The video count number is every time an image is formed regardless of the kind of the actually used ATR, and the counted result is stored in a RAM 68. Thus, information equivalent to toner consumption just before can be utilized even when the inductance detection ATR is switched to the video count ATR, so that the toner equivalent to the toner consumed to form the image previous time is supplied in image forming processing just after switching. Therefore, the appropriate toner concentration is maintained even in the succeeding image forming processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer, a facsimile, etc., which develops an electrostatic latent image formed on an image carrier by an electrophotographic system, an electrostatic recording system or the like to form a visible image. The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus including a developer concentration control device that appropriately controls the toner concentration of a two-component developer.

The present invention also relates to a process unit detachably attached to the image forming apparatus.

[0003]

2. Description of the Related Art A developing device included in an electrophotographic or electrostatic recording type image forming apparatus has been using a two-component developing method using a two-component developer mainly containing toner and carrier for a long time. There is. Since the two-component developing method is more stable than other developing methods in terms of the tint of an image and the like, it is often used especially in an image forming apparatus intended to form a full-color image.

As is well known, the toner concentration of a two-component developer (hereinafter defined as the ratio of toner to the total weight of toner and carrier) is a very important factor for stabilizing image quality. Is. Since the toner is consumed in the developing process and the toner concentration fluctuates, an automatic toner replenishment control device (AT) which detects the toner concentration of the developer at a proper time and replenishes an appropriate amount of toner according to the variation.
R) is used, and it is necessary to always keep the toner concentration within a certain allowable range with respect to a predetermined index value.

An automatic toner replenishment controller (ATR) is generally a toner replenishment amount control unit that processes the output data of the toner concentration detection unit that detects the toner concentration of the two-component developer and the toner concentration detection unit to determine the toner replenishment amount. Section, a toner replenishment unit that actually supplies toner based on the toner replenishment amount determined by the toner replenishment amount control unit.

Various methods are known for detecting the toner density in the toner density detecting section. For example, by utilizing the fact that the light reflectance of the developer in the developer container or on the developer carrier changes depending on the toner concentration, a method of detecting the toner concentration by an optical sensor, the magnetic permeability of the developer changes depending on the toner concentration. By utilizing this, a method of detecting toner concentration using an inductance sensor that converts magnetic permeability into an electric signal, and a change in light reflectance of a predetermined patch image formed under a predetermined condition on a latent image carrier can be used. For example, there is a method of detecting and indirectly estimating the toner concentration of the developer.

Further, in an image forming apparatus of the type that forms a digital latent image using a laser scanner, an LED array, etc., the cumulative value of the number of print pixels in the image information signal per page (hereinafter referred to as "video count number"). It is possible to estimate the toner consumption amount per page relatively accurately. Therefore, it is possible to use an automatic toner replenishment control device (hereinafter referred to as "video count ATR") that determines the toner replenishment amount in accordance with the estimated consumption amount. The video count ATR has a great advantage in terms of cost since it does not require a toner density detection unit, but it has a problem that the error of the toner replenishment amount is gradually accumulated, and some means for correcting the error is additionally required. , It is currently avoided to use it alone.

In a color image forming apparatus having a plurality of developing devices, there is a demand for downsizing of the developing device including the toner concentration detecting section as described above, which is easily affected by toner scattering and the like, so that the optical path and the like are not affected. An automatic toner replenishment control device (hereinafter referred to as “inductance detection ATR”) that uses a toner concentration detection device that uses an inductance sensor that requires only a sensor installation space is adopted rather than a toner concentration detection device that uses an optical sensor that requires a space to be secured. Often.

However, the inductance detection ATR
When using, there were the following problems. When the two-component developer is left for a long period of time (especially in a high humidity environment), the gap between the toner and the carrier particles may be clogged and the developer may “aggregate”. In this case, since the process of “aggregation of developer → increase in bulk density → increase in apparent magnetic permeability” is followed, although the toner concentration is actually proper,
The inductance detection ATR may erroneously detect that the toner concentration has decreased, and as a result, toner may be excessively replenished. Excessive replenishment of toner may cause deterioration of image quality such as image density and color balance, generation of fog, and further may lead to problems such as contamination of the image forming apparatus due to increased toner scattering.

In order to avoid this problem, a method has been proposed in which the inductance detection ATR is used in combination with the above-described video count ATR, and switching is performed as necessary. For example, inductance detection ATR and video count AT
R and a means for storing the detection data of the inductance detection ATR immediately before the operation of the image forming apparatus is stopped (hereinafter abbreviated as “stop data”) are provided, and the inductance at the time of the first image forming operation after the image forming operation is restarted. When the detected data of the detection ATR (hereinafter abbreviated as “restart data”) and the stored “stop data” are compared and a change of a predetermined amount or more is detected, the toner replenishment control method is changed from the inductance detection ATR. This is a method of switching to the video count ATR.

The developer, which has once agglomerated, is gradually disentangled and recovered to the state before the agglomeration by sufficient stirring and appropriate toner consumption. Video count A only for the period required for this recovery
TR is performed, and after the developer is recovered, it is returned to the inductance detection ATR again. The recovery of the developer can be performed by, for example, one of cumulative values such as "sheet passing number", "stirring time", "replenishment toner amount", and "video count number" from the time of the first image forming operation after the image forming operation is restarted. Or (or the calculated value of a function that combines some of these parameters)
Can be estimated by considering that it has recovered when it reaches a predetermined value. Further, the recovery period for switching to the inductance detection ATR may be extended or shortened depending on the difference between the “restart data” and the “stop data”.

[0012]

However, the above-described inductance detection ATR and video count AT are set.
In each of R, toner is supplied according to the toner density change detected (estimated) during the image forming operation during the next image forming operation. The problem here is that since the ATR to be used is not determined when the image forming apparatus is stopped and then restarted, for example, the inductance detection ATR is switched to the video count ATR. In this case, there is no video count for estimating the amount of toner consumed in the previous image forming process, and thus toner supply is not performed in the first image forming operation after the image forming operation is restarted.

Further, as a result of comparing the "data at restart" with the stored "data at stop", the video count AT
When the density control is switched to R, the video count AT
Since R only serves to maintain the toner concentration at the time of the first image forming operation after the image forming operation is resumed, even if the toner concentration at the time of the first image forming operation deviates from the reference toner concentration, it cannot be corrected. For example, when outputting an image with a very high print ratio and stopping the image forming device,
If toner is not replenished in the first image forming operation, the possibility of switching to the video count ATR increases slightly, and even if the toner density at that time is lower than the reference value, while the video count ATR continues. Will maintain the toner density at a low level.

Further, in the inductance detection ATR / video count ATR switching system as described above, the inductance at the time when the image forming apparatus is stopped is compared with the inductance at the first image forming operation after the image forming operation is restarted. If toner is not replenished during the image forming operation of
It may affect the results to some extent.

In some cases, the process unit including the developing device can be easily attached to and detached from the image forming apparatus for the purpose of improving maintenance. In this case, it is assumed that the process unit is replaced with another process unit. When the toner concentration information of the developing device is stored in the image forming device, the stored toner concentration information and the toner concentration information of the replaced process unit are different, and the toner replenishment amount may be incorrect. It was Therefore, the process unit may not be replaced.

An object of the present invention is to detect an inductance AT
To provide an image forming apparatus capable of maintaining an appropriate toner density and a control method thereof in an image forming apparatus in which R and video count ATR are switched and used.

Another object of the present invention is to provide a developing device incorporated in a detachable process unit,
An object is to provide an image forming apparatus and a process unit that can be replaced while maintaining an appropriate toner density.

[0018]

That is, the gist of the present invention is to provide a two-component developer in an image forming apparatus for forming an image based on image data using a two-component developer containing toner particles and carrier particles. First, a toner replenishment amount is calculated based on the detected toner concentration and a predetermined reference concentration.
Toner replenishment amount calculation means, second toner replenishment amount calculation means for counting the number of print pixels included in a predetermined unit of image data, and calculating the toner replenishment amount based on the number of print pixels, and second toner The difference between the storage unit that stores the toner replenishment amount calculated by the replenishment amount calculation unit for the image data on which the image was previously formed and the difference between the previous toner concentration detected by the first toner replenishment amount calculation unit and the current toner concentration Based on the toner replenishment amount calculation means, the toner replenishment means for replenishing toner particles based on the toner replenishment amount calculated by the selected toner replenishment amount calculation means. The image forming apparatus is characterized.

Another object of the present invention is a process unit which is built in a developing device using a two-component developer containing toner particles and carrier particles and is detachably attached to an image forming device. When mounted on the forming apparatus, it has a non-volatile storage means accessible by the image forming apparatus, and the storage means is based on the number of print pixels included in the image data on which the image was formed last time or the number of print pixels. The process unit is characterized in that the calculated toner supply amount is stored.

Another aspect of the present invention is a method for controlling an image forming apparatus, which forms an image based on image data using a two-component developer containing toner particles and carrier particles. A first toner replenishment amount calculation step of detecting the concentration of toner particles (toner concentration) in the agent and calculating the toner replenishment amount based on the detected toner concentration and a predetermined reference concentration, and a predetermined unit of image data. A second toner replenishment amount calculation step of counting the number of print pixels included and calculating the toner replenishment amount based on the number of print pixels, and the image data on which the image was previously formed in the second toner replenishment amount calculation step were calculated. Based on the difference between the storage step of storing the toner replenishment amount, the previous toner concentration detected in the first toner replenishment amount calculation step, and the current toner concentration, And a toner replenishment step of replenishing toner particles based on the toner replenishment amount calculated in the selected toner replenishment amount calculation step. It depends on the control method.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on its preferred embodiments with reference to the drawings. In the following description, an electrophotographic digital copying machine is exemplified as the image forming apparatus according to the embodiment of the present invention.
In the present invention, a latent image corresponding to an image information signal is formed on an image carrier such as a photoconductor or a dielectric by an electrophotographic system, an electrostatic recording system, or the like, and the latent image is composed mainly of toner particles and carrier particles. By using a developing device that uses the two-component developer described above, a visible image (toner image) is formed, the visible image is transferred to a transfer material such as paper, and a fixing unit forms a permanent image. It is applicable to general devices.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 3 is a diagram showing a configuration example of a main part of an electrophotographic digital copying machine as an example of the image forming apparatus according to the exemplary embodiment. In FIG. 1, the image of the original 31 to be copied is the lens 3
The image is projected onto the image pickup device 33 such as a CCD by means of 2. The image sensor 33 decomposes the image of the document 31 into a large number of pixels and generates an analog image signal corresponding to the density of each pixel. The analog image signal output from the image sensor 33 is sent to the image signal processing circuit 34, where it is converted into a pixel image signal which is image data corresponding to the density of each pixel.

The photosensitive drum 40 is an electrophotographic photosensitive drum that has amorphous silicon, selenium, OPC, etc. on its surface and rotates in the direction of the arrow. After being uniformly discharged by the exposure device 41, the primary charger 42 is used. Are uniformly charged by.

The pixel image signal is a pulse width modulation circuit 3
5, the laser driving pulse corresponding to the pixel image signal is supplied to the semiconductor laser 36, and the semiconductor laser 36 is caused to emit light for a time corresponding to the pulse width. The laser beam 36a emitted from the semiconductor laser 36 is scanned by the rotary polygon mirror 37, and an image is formed on the photosensitive drum 40 by a lens 38 such as an f / θ lens or a fixed mirror 39. Therefore, the laser beam 36a is irradiated on the photosensitive drum 40 in the main scanning direction in a longer range for high-density pixels and a shorter range for low-density pixels, and the area corresponding to the pixel image signal is irradiated. An electrostatic latent image having gradation is formed.

This electrostatic latent image is developed by a developing device 44 using a two-component developer 43 in which toner particles and carrier particles are mixed as main components, and a visible image (toner image) is formed on the photosensitive drum 40. To be done. The formed toner image is transferred by the transfer charger 49 to the transfer material 48 held on the transfer material carrier belt 47 which is supported by the two rollers 45 and 46 and is endlessly driven in the direction of the arrow in the figure. To be done.

In FIG. 1, one image forming station (photosensitive drum 40, exposure device 4) is shown for the sake of simplicity.
1, including the primary charging device 42, the developing device 44, the cleaning device 50, etc.). In the case of a color copying machine, four image forming stations having, for example, cyan, magenta, yellow, and black color developers are sequentially provided on the transfer material carrying belt 47 along the moving direction thereof. Then, the pixel image signal is separated for each color, and the semiconductor laser 36 driven by the pixel image signal of each color is
Laser light 36a of the above is irradiated onto the photosensitive drum of each image forming station having the developer of the corresponding color. The color-separated toner images for each color of the original formed at each image forming station are sequentially transferred to the transfer material 48 that is held and conveyed by the transfer material carrying belt 47 to form a full-color toner image.

Details of the developing device 44 in FIG. 1 are shown in FIG. The developing device 44 is arranged so as to face the photoconductor drum 40, and the inside thereof is partitioned into a first chamber (developing chamber) 52 and a second chamber (stirring chamber) 53 by a partition wall 51 extending in the vertical direction. ing. In the first chamber 52, a non-magnetic developing sleeve 54, which is a developer bearing member that rotates in the direction of the arrow, is arranged, and a magnet 55, which is a magnetic field generating means, is fixedly arranged in the developing sleeve 54. The developing sleeve 54 carries and conveys a layer of a two-component developer (including magnetic carrier and non-magnetic toner) whose thickness is regulated by a blade 56 that limits the amount of developer, and in a developing area facing the photoconductor drum 40. The developer is supplied to the photosensitive drum 40 to develop the electrostatic latent image. In order to improve the developing efficiency, that is, the rate of applying toner to the latent image, a developing bias voltage in which a DC voltage is superimposed on an AC voltage is applied from a power source 57 to the developing sleeve 54.

First and second developer stirring screws 58 and 59 are arranged in the first chamber 52 and the second chamber 53, respectively. The first screw 58 stirs and conveys the developer in the first chamber 52, and the second screw 59 uses the toner 63 supplied from the toner replenishing tank 60 shown in FIG. 1 and the developer already in the developing device. 43 and agitate and convey
Make the toner density uniform. In the present embodiment, the toner replenishing device includes a conveying path 61 that connects the toner replenishing tank 60 and the toner replenishing port of the developing device 44, a conveying screw 62 provided in the conveying path 61, a drive motor 70 that drives the conveying screw 62, and a driving motor 70. It is composed of a drive circuit 69 for controlling the motor 70. Then, when toner replenishment is performed based on the detection result of the inductance head 20, which will be described later, as a replenishing device of the inductance detection ATR, when toner replenishment is performed under the control of the CPU 67 based on the count value of the pixel image signal, the video is supplied. It operates as a supply device for the count ATR.

In the partition wall 51, a developer passage (not shown) connecting the first chamber 52 and the second chamber 53 is formed on the front side and the rear side in FIG. 2, and the first and second screws are formed. The toner in the first chamber 52, whose toner concentration has been lowered due to the development, is moved to the second chamber 53 from one of the passages by the conveyance powers 58 and 59, and the toner concentration in the second chamber 53 is increased. The recovered developer of is moved into the first chamber 52 from the other passage.

In the present embodiment, in order to detect the change in the toner density in the developing device 44 and control the amount of replenishment toner,
As shown in FIG. 2, the inductance head 20 of the inductance sensor is installed on the bottom wall of the first chamber (developing chamber) 52. For example, as shown in FIG. 4, the output electric signal from the inductance head 20 changes substantially linearly according to the toner concentration (toner / carrier (T / C) ratio (%)), and is optimum in this embodiment. The toner density is adjusted to 2.5V at a certain toner concentration (6%).

The detection data obtained by converting the output electric signal from the inductance head 20 into digital data by an AD conversion circuit (not shown) is C as toner replenishment amount control means.
It is sent to PU 67 (FIG. 1).

As shown in FIG. 1, a non-volatile RAM 68, which is a storage means, is connected to the CPU 67. RA
In M68, detection data (that is, "initial value") corresponding to the specified toner density at the initial setting value is stored from the inductance head 20 via the CPU 67, and the temperature and humidity detected by a temperature and humidity detection unit (not shown) are stored. A corresponding predetermined “correction value” table is also stored in advance. In the present embodiment, the “correction value” and the “initial value” corresponding to the above temperature and humidity are read out from the RAM 68 to the CPU 67 and added to obtain the “reference value”.

The CPU 67 compares the detection data newly obtained from the inductance head 20 with the above-mentioned "reference value", and supplies the insufficient toner corresponding to the difference to the developing device 44.
The rotation time of the conveying screw 62 required for replenishment is calculated, the motor drive circuit 69 is controlled, and the motor 70 is rotationally driven for that time. The conveying screw 62 rotates for the above-mentioned time, and moves from the toner supply tank 60 to the developing device 44.
Replenish the shortage toner. That is, the toner supply amount is controlled by controlling the driving time of the motor 70.

If excessive toner replenishment is detected,
The CPU 67 calculates the amount of excess toner in the developer, and when the image is formed on the original document thereafter, the amount of toner replenishment is reduced so that the amount of excess toner is eliminated, or toner is replenished until the amount of excess toner is consumed. Do not control. When the excess toner amount is consumed, the normal toner supply operation is performed as described above.

To replenish the toner, the first and second developer stirring screws 5 are arranged so that the toner density is not made non-uniform.
This is done when 8, 59 are driven. In a color image forming apparatus having a plurality of developing devices, the developing sleeve 54 and the first and second developer stirring screws 58 and 59 are often driven by the same drive system for cost reduction. In such a case, as a result, toner replenishment is limited to the time of image formation.

With the above-mentioned structure, as described in the section "Prior Art", when the image forming apparatus is not operated for a long period of time, the developer is aggregated and the toner density is constant. Despite this, a difference may occur in the detection signal (“restart data” and “stop data”) of the inductance detection ATR, and an error may occur in toner concentration control.

For example, as shown in FIG. 5A, the bulk density of the developer increases with the time from when the apparatus is stopped until the operation is restarted. As a result, as shown in FIG. 5B, the detection data by the inductance head 20 also increases when the device operation is restarted. Therefore, the CPU 67 determines that the toner concentration of the developer is low, and controls the replenishing device to replenish the toner so that the value of the detection data decreases.
As a result, as shown in FIG.
It deviates from the toner concentration of%, and becomes stable in the state of excessive toner concentration. This excessive toner concentration state continues until the developer agglomeration is resolved and the bulk density is restored.

Therefore, in this embodiment, in order to correct the erroneous detection of the inductance detection ATR due to the leaving of the developer and to keep the toner concentration at a predetermined value immediately after the operation is stopped, the video is used as the second developer concentration control means. Toner density control is performed using the count ATR.

First, the video count ATR in this embodiment will be described. As shown in FIG. 1, in the digital copying machine of this embodiment, one of the AND gates 64 receives a laser drive pulse (pulse shown in FIG. 3A) corresponding to the pixel image signal transmitted from the pulse width modulation circuit 35. Of the clock pulse oscillator 65 to the other input.
The clock pulse (the pulse shown in FIG. 3B) from is supplied. The output of the AND gate 64 is the number of clock pulses (s, l, m shown in FIG. 3C) corresponding to the pulse width of the laser driving pulse (for example, s, l, m pulses shown in FIG. 3A). Pulse), that is, the number of clock pulses corresponding to the density of each pixel is output.

This clock pulse is integrated by the counter 66 for each image (one page of the original document) to calculate the video count number C1 (for example, the maximum video count number of one A4 original document is 400 dpi, a pixel image signal of 256 gradations). About 3884 × 10 ^ 6). This video count number corresponds to the amount of toner consumed to form a toner image for one page of the original 31. CPU 67 is counter 6
The conversion table showing the correspondence between the video count number registered in the RAM 68 in advance and the toner replenishment time is read from the video count number C1 output from No. 6 and consumed by controlling the drive time of the motor 70 as described above. Replenish the toner so that the toner amount is supplemented.

Both the inductance detection ATR and the video count ATR used in this embodiment are
There is a time difference between the time when the toner is consumed and the time when the toner density is detected (or estimated) and the toner is replenished based on the detection (estimation) result.

In the case of the inductance detection ATR, since the inductance detection is performed at the initial stage of image formation, the toner density actually detected is the toner density of the developer consumed in the previous image formation. In summary, "the toner density of the previous image formation is detected by the image formation currently in progress to determine the toner replenishment amount, and the toner is replenished during the image formation currently in progress". Therefore, when the developer agglomerates or the like and the detection result of the image formation currently in progress is unreliable, the latest toner density information for toner replenishment cannot be obtained.

On the other hand, in the video count ATR, the video count for one page is performed at the same time when the latent image is formed. Therefore, the toner supply corresponding to the toner consumption amount obtained by performing the video count is performed in the next image. It is the time of formation. In summary, "The toner density (toner consumption amount) of the previous image formation is estimated, and the toner replenishment amount (=
Toner consumption amount) is determined, and the toner is replenished during image formation which is currently in progress. ” Therefore, even if the developer agglomerates (packing) or the like occurs, if the toner density information (toner replenishment amount) of the previous image formation remains, toner replenishment can be performed without any problem.

However, in the method of selecting and switching between the inductance detection ATR and the video count ATR depending on the packing state of the developer as in the present embodiment, it is determined that packing has occurred, and then the video count ATR is switched to. Since the video count number is recorded for the first time, toner is not replenished in the first image forming operation after the image forming operation is restarted. Especially when an image with a high printing ratio is output in the last image formation before packing, the image formation is performed while the toner concentration is kept low because the video count ATR cannot autonomously bring the toner concentration close to the reference value. Will continue.

Therefore, in this embodiment, the video count number is counted for each image formation and the result is stored in the RAM 68 regardless of the type of ATR actually used. As a result, even when the video count ATR is switched, information corresponding to the toner consumption amount immediately before is available, and the toner consumed in the previous image formation can be replenished in the image forming process immediately after the switching. . Therefore, it is possible to maintain an appropriate toner density even in the subsequent image forming processing.

Switching control between the inductance detection ATR and the video count ATR in this embodiment will be described with reference to the flowchart of FIG.

First, when the pixel image signal is received from the image signal processing circuit 34, the image forming operation is started (S60).
1). The detection data (data at restart) a obtained by AD-converting the detection voltage signal from the inductance head 20 is the CPU 6
7 is sent (S602), and at the same time, counting of the video count number Cnew in the current image formation is started (S603). Next, the detection data (stop data) b obtained by AD-converting the detection voltage signal from the inductance head 20 during the previous image formation and the video count C1 counted during the previous image formation are sent from the RAM 68 to the CPU 67 (S604). .

Subsequently, the CPU 67 calculates the difference data Δ (= ab) from the restart data a and the stop data b (S605), and then compares the difference data Δ with a predetermined allowable threshold d. (S606). If Δ ≦ d (Yes), it is determined that the packing of the developer has not occurred, and the inductance detection ATR is selected for the toner concentration control (S6).
07), and toner supply is performed based on the restart data a (S608).

On the other hand, if Δ> d (No) in S606, it is determined that packing has occurred, the video count ATR is selected (S609), and the CPU 67 replenishes toner based on the video count number C1 (S60). S61
0). After the video count number Cnew is counted (S611), the result Cnew of the current video count is set as a new C1 (C1 = Cnew) regardless of which ATR is selected, and C1 of the RAM 68 is updated. (S612).

As described above, in this embodiment, the video count number is counted for each image forming process and the result is stored in the RAM 68.
The toner can be replenished from the time of switching to the video count ATR.

(Second Embodiment) Next, a second embodiment of the present invention will be described. The image forming apparatus according to the present embodiment may have the same configuration as the digital copying machine (FIGS. 1 and 2) described in the first embodiment, except that a detachable process unit is used. Therefore, the same reference numerals are used for the components that are common to those of the first embodiment, and the redundant description of the same operations will be omitted.

FIG. 7 is a diagram showing a configuration of a main part relating to toner density control in the digital copying machine according to the present embodiment. As shown in FIG. 7, in the present embodiment, the photosensitive drum 40, the exposure device 41, the primary charging device 42, the developing device 44, and the cleaning device 50, which constitute one image forming station in the first embodiment, are installed. Collectively, the process unit 80 configured to be detachable from the digital copying machine is used. When the digital copying machine is a color copying machine, four process units 80 corresponding to each color of cyan, magenta, yellow, and black are used.

Process unit 80 in this embodiment
As described with reference to FIG. 2, the developing device 44 is provided with the inductance head 20 for detecting the apparent magnetic permeability of the two-component developer. In addition, a nonvolatile RAM 81 as a storage unit that stores a video count number, which is data necessary for toner density control using the video count ATR.
Is provided. Inductance sensor (not shown)
The RAM 81 and the RAM 81 are configured to be connected to the CPU 67 in the image forming apparatus at the time of mounting via a connector and / or a contact (not shown).

In this embodiment, A actually selected
Regardless of the TR method, the video count number is always measured and stored in the RAM 81 for each image formation, and when the image forming apparatus is restarted (when power is turned on or when the apparatus is stopped due to sleep mode or paper jam, etc.). ) Is forced to execute the toner supply by the video count ATR.

The toner replenishing operation when the image forming apparatus is restarted in this embodiment will be described with reference to the flowchart of FIG. When the recovery operation of the image forming apparatus starts (S80
1), the CPU 67 is the RAM 81 of the process unit 80
Then, the video count number C1 counted at the previous image formation is read (S802). Further, in parallel, the first and second developer stirring screws 58, 5 of the developing device 44 are also provided.
9 is driven for a certain period of time (S803).

Next, the CPU 67 calculates the replenishment amount based on the read video count number C1, controls the motor 70 while the first and second developer agitating screws 58 and 59 are driven, and the conveying screw. The toner is replenished by rotating 62 for a required time (S804). After the driving of the first and second developer stirring screws 58 and 59 is stopped (S805), the video count C1 is reset (C1
= 0) (S806). Next, the image forming standby state is entered (S807). After that, the same processing as that described in the first embodiment using FIG. 6 is performed.

In the first embodiment, before the switching judgment of the inductance detection ATR / video count ATR is made,
Since the toner consumed during the previous image formation is not replenished, when the image output with a high print ratio is performed in the previous image formation, the ATR switching determination may be affected. However, as in the present embodiment, by performing the toner replenishment for the amount of toner consumed at the time of the previous image formation before performing the ATR switching determination, a more appropriate ATR switching (selection) is performed.
Will be possible.

Further, in this embodiment, the detachable process unit is provided with the non-volatile RAM 81 for storing the video count number C1 at the time of the previous image formation. As a result, the compatibility of the process unit is maintained, and even if the process unit is replaced with another process unit (having the nonvolatile RAM 81) during use, the process unit in use is replaced with another image forming apparatus of the same model and used. Also makes it possible to appropriately control the toner density.

Information indicating that the number of print pixels is 0 is stored in the RAM 81 when the process unit in this embodiment is unused.

[0060]

Other Embodiments In the above-described first embodiment, before selecting the ATR to be used when the image forming apparatus is restarted (when the power is turned on or when the apparatus is returned from the apparatus stop due to a sleep mode or a paper jam). Although the toner is not replenished to the ATR, the ATR as described in the second embodiment is not used.
It is also possible to configure to forcibly supply toner before switching (selection). In this case, in the flowchart described with reference to FIG. 8, it is only necessary to change the read / update destination of the video count number C1 from the RAM 81 to the RAM 68.

Further, in the above embodiment, the RAM
Although only the case where the video count number is stored in the 68 and the RAM 81 has been described, the toner supply amount calculated from the video count number may be stored. In that case, if the process unit according to the second embodiment is unused, information indicating that toner replenishment is unnecessary is stored.

Another object of the present invention is to supply a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to supply a computer (or CPU) of the system or apparatus.
It is needless to say that it can be achieved by reading and executing the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention.

A storage medium for supplying the program code is, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD.
-R, magnetic tape, non-volatile memory card, ROM, etc. can be used.

Further, not only the functions of the above-described embodiment are realized by executing the program code read by the computer, but also the OS (operating system) running on the computer based on the instructions of the program code. It is needless to say that this also includes a case where the above) performs a part or all of the actual processing and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written in the memory provided in the function expansion board inserted into the computer or the function expansion unit connected to the computer, based on the instruction of the program code, It goes without saying that a case where the CPU or the like included in the function expansion board or the function expansion unit performs some or all of the actual processing and the processing realizes the functions of the above-described embodiments is also included.

When the present invention is applied to the above storage medium, the storage medium stores the program code corresponding to the above-described flowchart (shown in at least one of FIG. 6 and FIG. 8). .

[0068]

As is apparent from the above description, according to the image forming apparatus of the present invention, the object of the present invention is to maintain an appropriate toner density by the inductance detection ATR / video count ATR switching system. An image forming apparatus can be provided. Further, it is possible to provide an image forming apparatus and a process unit which are compatible with each other while maintaining the proper toner density.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a digital copying machine as an example of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a developing device in FIG.

3 is a diagram illustrating a counting principle of a video count number in the image forming apparatus of FIG.

FIG. 4 is a diagram showing a change in developer concentration and a change in a detection signal of an inductance sensor.

FIG. 5: Inductance detection ATR due to aggregation of developer
FIG. 5 is a diagram illustrating a mechanism that causes a false detection in FIG.

FIG. 6 is a flowchart illustrating a toner supply operation according to the first exemplary embodiment.

FIG. 7 is a diagram showing a configuration example of a process unit according to a second embodiment.

FIG. 8 is a flowchart illustrating a forced toner replenishing operation performed when the image forming apparatus returns to operation in the second embodiment.

Claims (12)

[Claims] 1. An image forming apparatus for forming an image based on image data using a two-component developer containing toner particles and carrier particles, wherein the concentration of the toner particles (toner concentration) in the two-component developer is First toner replenishment amount calculation means for detecting the toner replenishment amount based on the detected toner concentration and a predetermined reference concentration, and counting the number of print pixels included in a predetermined unit of the image data. Second toner replenishment amount calculation means for calculating the toner replenishment amount based on the number of print pixels, and storage means for storing the toner replenishment amount calculated by the second toner replenishment amount calculation means for the image data of the image previously formed. The first toner replenishment amount calculation means detects the first toner concentration based on the difference between the previous toner concentration and the current toner concentration.
And one of the second toner replenishment amount calculation means,
An image forming apparatus comprising: a toner replenishing unit that replenishes toner particles based on the toner replenishing amount calculated by the selected toner replenishing amount calculating unit. 2. The image forming apparatus according to claim 1, wherein the first toner replenishment amount calculation means detects the toner density based on an apparent magnetic permeability of the two-component developer. 3. The image forming apparatus according to claim 1, wherein the predetermined unit of the image data corresponds to the unit of image formation. 4. The second toner replenishment amount calculation means calculates the toner replenishment means before the selection when the image forming apparatus is in a state of executing an image forming process from a predetermined state. 4. The image forming apparatus according to claim 2, wherein the toner replenishment is performed based on the toner replenishment amount. 5. When the image forming apparatus changes from a predetermined state to a state in which an image forming process is executed, the toner replenishing unit is based on the toner replenishing amount stored in the storage unit before the selection is performed. The image forming apparatus according to any one of claims 1 to 3, wherein the toner replenishment is performed by performing toner replenishment. 6. A process unit having a built-in developing device using a two-component developer containing toner particles and carrier particles, the process unit being configured to be attachable to and detachable from an image forming apparatus, wherein the process unit is mounted on the image forming apparatus. The image forming apparatus includes a non-volatile storage unit accessible by the image forming apparatus, and the storage unit includes the number of print pixels included in the image data of the previous image formation, or toner replenishment calculated based on the number of print pixels. A process unit characterized in that a quantity is stored. 7. The storage unit stores information indicating that the number of print pixels is 0 or that toner supply is unnecessary when the process unit is not used. The process unit according to claim 6. 8. A method of controlling an image forming apparatus which forms an image based on image data using a two-component developer containing toner particles and carrier particles, the concentration of the toner particles in the two-component developer. A first toner replenishment amount calculating step of detecting (toner concentration) and calculating a toner replenishment amount based on the detected toner concentration and a predetermined reference concentration; and the number of print pixels included in a predetermined unit of the image data. And a second toner replenishment amount calculation step of calculating the toner replenishment amount based on the number of print pixels, and a toner replenishment amount calculated for the image data previously image-formed in the second toner replenishment amount calculation step. Based on the difference between the storage step of storing and the previous toner density detected in the first toner replenishment amount calculation step and the current toner density, And a toner replenishment step of replenishing toner particles based on the toner replenishment amount calculated in the selected toner replenishment amount calculation step. Control method. 9. The control of the image forming apparatus according to claim 8, wherein the first toner replenishment amount calculation step detects the toner density based on an apparent magnetic permeability of the two-component developer. Method. 10. The method of controlling an image forming apparatus according to claim 8, wherein the predetermined unit of the image data corresponds to the unit of image formation. 11. When the image forming apparatus changes from a predetermined state to a state where an image forming process is executed, the toner replenishment step calculates the second toner replenishment amount calculation step before the selection. 11. The method for controlling an image forming apparatus according to claim 9, wherein the toner replenishment is executed based on the toner replenishment amount. 12. When the image forming apparatus is in a state of executing an image forming process from a predetermined state, the toner replenishment step is based on the toner replenishment amount stored in the storage step before the selection. 11. The toner replenishment is performed by executing the toner replenishment according to any one of claims 8 to 10.
Item 6. A method for controlling an image forming apparatus according to item.