JP2009075282A - Developing device, process unit and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing the occurrence of carrier deposition during initial printing caused by variations in the looseness apparent density of toner. <P>SOLUTION: The looseness apparent density information of an initial agent in a developing device is stored in a nonvolatile RAM disposed in the developing device. When an initial operation is performed by a user, the upper limit of an output voltage stored in the IC chip of a toner concentration detection sensor composed of a magnetic permeability sensor is corrected based on the looseness apparent density information, and then the toner concentration of the initial agent is adjusted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  According to the present invention, based on the result of detecting the toner concentration of the initial agent contained in the developing device by the toner concentration detecting means, the toner of the developer in the developing device is consumed and the toner concentration of the initial agent is reduced. The present invention relates to a forming apparatus. The present invention also relates to a developing device and a process unit used in such an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a printer, or a facsimile machine, a latent image on a latent image carrier is developed with a developer containing toner and a magnetic carrier. In this type of image forming apparatus, the toner density of the developer is kept constant by replenishing the toner in the developing apparatus based on the result of detecting the decrease in the toner density of the developer accompanying the development by the toner density detection sensor. It is generally performed to keep within the range.

  In such an image forming apparatus that maintains a constant toner density, there is known an apparatus that calibrates a toner density detection sensor as follows (for example, one described in Patent Document 1). That is, an initial agent adjusted to a predetermined toner density is set in the developing device when shipped from the factory. When the power is turned on for the first time after being delivered to the user, the toner concentration of the initial agent is detected by a toner concentration detection sensor. Then, the control voltage input to the toner concentration detection sensor is adjusted so that the output voltage value from the toner concentration detection sensor at this time becomes a predetermined value. As a result, the toner concentration detection sensor is calibrated so that a voltage having a predetermined value is output for a predetermined toner concentration.

  As the toner concentration sensor, a sensor comprising a magnetic permeability sensor for detecting the magnetic permeability is generally used. FIG. 8 is a graph showing an example of the relationship between the output voltage Tt of the toner concentration detection sensor including a magnetic permeability sensor and the toner concentration of the developer. As illustrated, the higher the toner concentration of the developer, the lower the output voltage Vt of the toner concentration detection sensor. This is because as the toner concentration of the developer increases, the density of the magnetic carrier per unit volume decreases and the permeability of the developer decreases. Since the slope of this graph, that is, the sensitivity of the toner density detection sensor varies from product to product, in recent toner density detection sensors, the sensitivity is measured before shipment and stored in an IC chip with a built-in sensor. I am letting.

  Hereinafter, an example in which an initial agent having a toner concentration adjusted to 7 [wt%] is used will be described. For the measurement of the sensitivity of the toner density detection sensor, for example, a magnetic sample that can obtain the same magnetic permeability as that of a developer containing a standard loose apparent density toner in a ratio of 4, 7, 10 [%] is detected. This is done by measuring the output voltage Vt at the time. When the toner concentration detection sensor is calibrated as described above, a sensitivity graph such as that shown in FIG. 9 stored in an IC chip with a built-in sensor can be used. Based on this graph, the output voltage Vt corresponding to 7 [wt%], which is the toner concentration of the initial agent, is 2.7 [V], which matches the value at the time of calibration.

  In the developing device immediately after the sensor calibration, the developer is in an initial agent state in which no toner is consumed, but the toner concentration of the initial agent is not necessarily a value suitable for subsequent development. This is because even if the toner density of the developer is a predetermined value, the image density varies depending on the environment. Specifically, in a high-temperature and high-humidity environment, even if the developer is stirred in the developing device, the triboelectric charge amount of the toner cannot be increased satisfactorily. Then, the charge amount (Q / M) per unit weight of the toner becomes smaller than usual, and the toner adhesion amount per unit area with respect to the latent image having a predetermined potential increases. As a result, if development is performed with the toner concentration of the initial agent, a large amount of toner may adhere to the latent image and the image density may be higher than the target. On the other hand, in a low temperature and low humidity environment, the toner is excessively frictionally charged as the developer is agitated, so that only a small amount of toner can adhere to the latent image. In addition, the image density may be made thinner than the target.

  Therefore, an image forming apparatus is known that adjusts the toner concentration of the initial agent as follows after sensor calibration. That is, first, a predetermined reference toner patch image is formed, and the toner adhesion amount (image density) per unit area with respect to the reference toner patch image is detected by a reflective photosensor or the like. When the detection result is smaller than the target value (when the image density is low), the reference toner patch image is formed again after the toner is supplied into the developing device. The toner supply, the formation of the reference toner patch image, and the detection of the toner adhesion amount are repeated until the toner adhesion amount on the reference toner patch image reaches the target value. On the other hand, when the toner adhesion amount on the reference toner patch image is larger than the target value (when the image density is high), a solid toner image for forced toner consumption is formed and the toner in the initial agent is forcibly consumed, and then the reference A toner patch image is formed again. The solid toner image formation, the reference toner patch image formation, and the toner adhesion amount detection are repeated until the toner adhesion amount on the reference toner patch image reaches the target value. By such an initial agent toner density adjustment process, development can be performed from the first sheet of the initial print with a developer having a toner density suitable for the environment.

  The toner density of the developer is adjusted within a range in which the output voltage Vt from the toner density detection sensor after calibration is not set higher than a predetermined upper limit value or lower than a predetermined lower limit value. Is common. This is for the reason described below. That is, if the toner density is excessively increased, a phenomenon called so-called soiling that causes toner to adhere to the background portion of the latent image carrier is caused. Further, if the toner density is excessively lowered, a phenomenon called so-called carrier adhesion that causes the magnetic carrier in the developer in the developing device to adhere to the latent image carrier is caused. The output voltage Tt is maintained within the range from the lower limit value to the upper limit value for the purpose of suppressing the occurrence of such dirt and carrier adhesion. Even when the toner concentration of the initial agent is adjusted as described above, the toner concentration is adjusted within the range from the lower limit value to the upper limit value of the output voltage Vt.

  “7-β” shown in FIG. 9 indicates the lower limit value of the toner concentration of the developer. If the toner concentration falls below this, carrier adhesion may occur. The voltage value corresponding to the lower limit value of the toner density is the upper limit value Vt1 of the output voltage Vt. Further, “7 + α” indicates the upper limit value of the toner concentration of the initial agent, and if the toner concentration is higher than this, there is a risk of causing soiling. The voltage value corresponding to the upper limit value of the toner density is the lower limit value Vt2 of the output voltage Vt. The upper limit value Vt1 and the lower limit value Vt2 are stored in the built-in IC chip of the toner concentration detection sensor together with the graph showing the sensor sensitivity. By using the upper limit values Vt1 and Vt2 for toner density control, it is possible to suppress the occurrence of background contamination and carrier adhesion.

JP 2007-225813 A

  However, even if the upper limit value Vt1 is adopted, there is a risk that the carrier is attached during initial printing and the latent image carrier such as the photoreceptor is damaged due to the variation in the apparent density of loose toner contained in the initial agent. I found out.

The reason will be described below.
Generally, even if a toner is manufactured in the same manufacturing method and environment, the loose apparent density (volume per unit mass) always varies from product to product. On the other hand, a toner concentration detection sensor comprising a magnetic permeability sensor does not detect the toner concentration itself of the developer, but detects the carrier density (developer bulk density) in the developer. Even if the toner concentration of the developer (weight ratio of toner to magnetic carrier) is constant, the carrier density in the developer will be different if the loose density of the toner is different. For this reason, even if the developer has the same toner concentration, the output value from the toner concentration detection sensor varies if the loose apparent density of the toner is different.

  The slope of the sensitivity graph shown in FIG. 9 is obtained when a standard loose apparent density toner is used, and the loose apparent density of the toner actually contained in the initial agent is a standard value. Not necessarily. When the apparent loose density of the toner in the initial agent is higher than a standard value, that is, when the volume per unit mass of the toner is relatively small, the toner concentration detection sensor that uses the initial agent as a test target is used. The graph of the output voltage Vt has a smaller slope as shown by the solid line in FIG. When the apparent density of loose toner is high, the change in the volume of the toner in the developer accompanying the change in the toner concentration is relatively small, and the rate of change in permeability with respect to the change in the toner concentration is relatively small. is there. In such a case, the upper limit value Vt1 of the output voltage Vt stored in the toner density detection sensor is “7-β−” which is lower than “7-β” which is the lower limit value of the toner density in the graph of the solid line in the figure. γ ”. That is, although the output voltage Vt is lower than the upper limit value Vt1, the toner density is lower than the lower limit value. This causes carrier adhesion.

  The present invention has been made in view of the above background, and an object thereof is to provide the following developing device, process unit, and image forming apparatus. That is, a developing device or the like capable of exhibiting a function useful for suppressing the occurrence of carrier adhesion during initial printing due to variations in the apparent density of loose toner.

In order to achieve the above object, a first aspect of the present invention provides a developer containing portion that contains a developer containing toner and a magnetic carrier, and a toner concentration detection that detects the toner concentration of the developer in the developer containing portion. And a developer carrier that develops the latent image on the latent image carrier with the developer in the developer container carried on its surface, the developer is set in the developer prior to factory shipment. The carrier density information in the initial agent, which is a new developer, or the loose apparent density information of the toner in the initial agent is attached to the housing of the developing device, or the carrier density information or the loose apparent density information is It is characterized in that density information storage means for storing electronic data is provided.
According to a second aspect of the present invention, in the developing device of the first aspect, an initial agent accommodating portion for accommodating the initial agent is detachably attached to the developing device main body, and the carrier density information or the loose apparent density information is provided. It is characterized in that it is attached to the initial agent container or the density information storage means is provided in the initial agent container.
According to a third aspect of the present invention, there is provided a latent image carrier for carrying a latent image, a latent image forming means for forming a latent image on the latent image carrier, and a developer containing a developer containing toner and a magnetic carrier. The latent image on the latent image carrier is developed by the developer container, the toner density detecting means for detecting the toner density of the developer in the developer container, and the developer in the developer container carried on its surface. A developing device having a developer carrying member, a toner replenishing means for replenishing the developer containing portion, and a toner concentration having an initial agent as a new developer set in the developing device as a test object While maintaining a state where the output value from the detection means is a value on the toner density side lower than a predetermined threshold value, a predetermined image for toner consumption is developed on the latent image carrier to adjust the toner concentration of the initial agent. An image comprising control means for performing a process of reducing In the image forming apparatus, the developing device according to claim 1 or 2 is used as the developing device, and information acquisition means for acquiring the carrier density information or the loose apparent density information attached to the developing device is provided, or A reading means for mechanically reading the loose apparent density information stored in the density information storage means is provided, and the threshold value is corrected based on the carrier density of the initial agent or the apparent loose density of the toner in the initial agent. Correction data storage means for storing correction data for correction, and based on the carrier density information or the loose apparent density information obtained by the information acquisition means or reading means, and the correction data, the threshold value The control means is configured to perform a process of correcting the above.
According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, as the toner density detecting means, sensitivity storage means for storing information on sensitivity, which is a rate of change of an output signal with respect to a change in toner density, in a machine-readable manner. The control is performed so that the threshold is corrected based on the sensitivity information stored in the sensitivity storage means and the carrier density information or the loose apparent density information. It is characterized by comprising means.
According to a fifth aspect of the present invention, in the image forming apparatus of the third or fourth aspect, as the developing device, the carrier density information or the loose apparent density information can be visually recognized as characters, symbols or code patterns of the developing device. What is attached to the housing is used, and as the information acquisition means, data input means for acquiring the character, symbol, or code pattern by an input operation by an operator is used.
5. The image forming apparatus according to claim 3, wherein the developing device is a device in which the carrier density information or the loose apparent density information is attached to a housing of the developing device as a visually recognizable character, symbol, or code pattern. In addition, as the information acquisition unit, a read conversion unit that reads an image of the character, symbol, or code pattern and converts the image into the carrier density information or the loose apparent density information based on the read result is used. To do.
According to a seventh aspect of the present invention, in the image forming apparatus according to the fifth or sixth aspect, the character, symbol, or code pattern is attached to the casing by laser processing.
The invention according to claim 8 is the image forming apparatus according to claim 6 or 7, characterized in that a sticker with the character, symbol or code pattern is attached to the casing.
According to a ninth aspect of the present invention, there is provided a latent image carrier for carrying a latent image, latent image forming means for forming a latent image on the latent image carrier, and development for developing the latent image on the latent image carrier. In an image forming apparatus comprising an apparatus and a toner replenishing means for replenishing toner to the developing device, at least the latent image carrier and the developing device are held by a common holding body, and 1 for the image forming apparatus main body. In the process unit configured to be detachable integrally as one unit, the developing device according to claim 1 or 2 is used as the developing device.

In these inventions, when the loose apparent density of the toner contained in the initial agent deviates from the standard value, for example, the output value of the toner density detection sensor such as the upper limit value Vt1 described above is set to a value on the low toner side. The threshold value for maintaining is deviated from an appropriate value. A good correlation is established between the deviation amount at this time and the deviation amount from the standard values of the carrier density and the loose apparent density. Therefore, if the correlation is examined by experiment, correction data for appropriately correcting the threshold value can be constructed based on the deviation amount of the carrier density or the loose apparent density from the standard value. In the present invention, the amount of deviation from the standard value of the carrier density of the initial agent or the amount of deviation from the standard value of the loose apparent density of the toner contained in the initial agent is controlled as follows. It is possible to ask the means. That is, first, the user is prompted to input carrier density information or loose apparent density information attached to the housing of the developing device, or carrier density information or loose apparent density stored in the density information storage means of the developing device. Information is read by the control means of the image forming apparatus. The control means obtains a difference between the carrier density information or the loose apparent density information thus obtained and a predetermined standard value, and a deviation amount from the standard value of the carrier density or the loose apparent density of the initial agent. Based on this deviation amount and the above-described correction data, it is possible to appropriately correct the threshold value to suppress the occurrence of carrier adhesion during initial printing due to the variation in the apparent density of loose toner.
As described above, in the present invention in which the carrier density information or the loose apparent density information is attached to the developing device or is stored in the density information storage means, the above-mentioned deviation amount can be grasped by the control means. A function useful for suppressing the occurrence can be exhibited.
In particular, in the inventions of claims 3 to 8, the initial agent is adjusted to a toner concentration suitable for the environment by toner consumption accompanying the formation of a toner consumption image, carrier density information or loose apparent density information, and correction data. Based on the above, the threshold value is appropriately corrected. As a result, it is possible to suppress the occurrence of carrier adhesion during initial printing due to variations in the apparent density of loose toner.

Hereinafter, an electrophotographic copying machine as an image forming apparatus to which the present invention is applied will be described.
FIG. 1 is a schematic configuration diagram showing a copying machine according to the present embodiment. The copying machine includes a printer unit 1 that forms an image on recording paper, a paper feeding device 200 that supplies the recording paper P to the printer unit 1, a scanner 300 that reads a document image, and automatically feeds a document to the scanner 300. An automatic document feeder (hereinafter referred to as ADF) 400 is provided.

  The scanner 300 is placed on the contact glass 301 as the first traveling body 303 equipped with a document illumination light source or mirror and the second traveling body 304 equipped with a plurality of reflecting mirrors reciprocate. Scanning of a document (not shown) is performed. The scanning light sent out from the second traveling body 304 is condensed on the imaging surface of the reading sensor 306 installed behind the imaging lens 305 and then read as an image signal by the reading sensor 306.

  On the side surface of the housing of the printer unit 1, a manual feed tray 2 for manually placing the recording paper P to be fed into the housing, and a paper discharge tray 3 for stacking the recording paper P after image formation discharged from the housing. Is provided.

  FIG. 2 is an enlarged partial configuration diagram illustrating a part of the internal configuration of the printer unit (1). In the casing of the printer unit (1), there is disposed a transfer unit 50 as transfer means for stretching an endless intermediate transfer belt 51 as an image carrier by a plurality of stretching rollers. The intermediate transfer belt 51 is driven by a driving roller 52, a secondary transfer backup roller 53, a driven roller 54, and four primary transfer rollers 55Y, 55Y, 55K, which are driven to rotate clockwise in FIG. While being stretched, the drive roller 52 is rotated endlessly in the clockwise direction in the drawing. Note that the suffixes Y, C, M, and K attached to the ends of the symbols of the primary transfer roller indicate the members for yellow, cyan, magenta, and black. Hereinafter, the subscripts Y, C, M, and K attached to the ends of the symbols are the same.

  The intermediate transfer belt 51 is greatly curved at the portions where the intermediate transfer belt 51 is wound around the driving roller 52, the secondary transfer backup roller 53, and the driven roller 54, so that the intermediate transfer belt 51 is stretched in an inverted triangular posture with the bottom side directed vertically upward. ing. The belt upper stretch surface corresponding to the base of the inverted triangle extends in the horizontal direction. Above the belt upper stretch surface, four process units 10Y, 10C, 10M, and 10K are provided on the upper stretch surface. It arrange | positions so that it may align with a horizontal direction along the extending direction.

  In FIG. 1 described above, an optical writing unit 68 is disposed above the four process units 10Y, 10C, 10M, and 10K. The optical writing unit 68 emits four writing lights L by driving four semiconductor lasers (not shown) by a laser control unit (not shown) based on the image information of the original read by the scanner 300. Then, the drum-shaped photoconductors 11Y, 11C, 11M, and 11K serving as latent image carriers of the process units 10Y, 10C, 10M, and 10K are scanned in the dark by the writing light L, respectively. , K, electrostatic latent images for Y, C, M, and K are written.

  In this embodiment, the optical writing unit 68 performs optical scanning by deflecting laser light emitted from a semiconductor laser by a polygon mirror (not shown) and reflecting the laser light by a reflection mirror (not shown) or passing through an optical lens. Is used. Instead of such a configuration, an LED array that performs optical scanning may be used.

  FIG. 3 is an enlarged configuration diagram showing the Y process unit 10 </ b> Y together with the intermediate transfer belt 51. The Y process unit 10Y includes a charging member 12Y, a charge eliminating device 13Y, a drum cleaning device 14Y, a developing device 20Y as developing means, a potential sensor 49Y, and the like around a drum-shaped photoconductor 11Y. And while these are hold | maintained with the casing which is a common holding body, it is attached and detached integrally as one unit with respect to a printer part.

  The charging member 12Y is a roller-like member that is rotatably supported by a bearing (not shown) while being in contact with the photoreceptor 11Y. The surface of the photoconductor 11Y is uniformly charged with, for example, the same polarity as that of Y toner by rotating in contact with the photoconductor 11Y while a charging bias is applied by a bias supply means (not shown). Instead of the charging member 12Y having such a configuration, a scorotron charger or the like that performs a uniform charging process in a non-contact manner on the photoconductor 11Y may be employed.

  A developing device 20Y in which a Y developer containing a magnetic carrier (not shown) and non-magnetic Y toner is contained in a casing 21Y has a developer conveying device 22Y and a developing unit 23Y. In the developing unit 23Y, a developing sleeve 24Y as a developer carrying member that is endlessly moved by being rotated by a driving unit (not shown) exposes a part of its peripheral surface to the outside through an opening provided in the casing 21Y. ing. As a result, a developing region is formed in which the photoconductor 11Y and the developing sleeve 24Y face each other with a predetermined gap.

  Inside the developing sleeve 24Y made of a non-magnetic hollow pipe-like member, a magnet roller (not shown) having a plurality of magnetic poles arranged in the circumferential direction is fixed so as not to rotate with the developing sleeve 24Y. The developing sleeve 24Y is driven to rotate while adsorbing the Y developer in the developer conveying device 22Y, which will be described later, to the surface by the magnetic force generated by the magnet roller, thereby pumping the Y developer from the developer conveying device 22Y. Then, the Y developer conveyed toward the developing area as the developing sleeve 24Y rotates, the doctor blade 25Y having the tip opposed to the surface of the developing sleeve 24Y with a predetermined gap, and the sleeve A doctor gap formed between the surface and the surface is entered. At this time, the layer thickness on the sleeve is regulated to substantially the same thickness as the doctor gap. When the developing sleeve 24Y is rotated and conveyed to the vicinity of the developing area facing the photoconductor 11Y, it receives a magnetic force of a developing magnetic pole (not shown) of the magnet roller and rises on the sleeve to become a magnetic brush. .

  For example, a developing bias having the same polarity as the charging polarity of the toner is applied to the developing sleeve 24Y by a bias supply unit (not shown). As a result, in the development region, non-development in which Y toner is electrostatically moved from the non-image portion side to the sleeve side between the surface of the development sleeve 24Y and the non-image portion (uniformly charged portion = background portion) of the photoreceptor 11Y. Potential acts. Further, a developing potential for electrostatically moving Y toner from the sleeve side toward the electrostatic latent image acts between the surface of the developing sleeve 24Y and the electrostatic latent image on the photoreceptor 11Y. The Y toner in the Y developer is transferred to the electrostatic latent image by the action of the developing potential, so that the electrostatic latent image on the photoreceptor 11Y is developed into the Y toner image.

  The Y developer that has passed through the developing area as the developing sleeve 24Y rotates is separated from the developing sleeve 24Y due to the influence of the repulsive magnetic field formed between the repelling magnetic poles provided in the magnet roller (not shown). The developer returns to the developer conveying device 22Y.

  The developer conveying device 22Y includes two first screw members 26Y, a second screw member 32Y, a partition wall interposed between the two screw members, a toner concentration detection sensor 45Y including a magnetic permeability sensor, and the like. The partition wall divides the first transport chamber, which is a developer transport section, in which the first screw member 26Y is accommodated, and the second transport chamber, which is a developer transport section in which the second screw member 32Y is accommodated. In the region facing both ends of the screw member in the axial direction, both transfer chambers are communicated with each other through an opening (not shown).

  The first screw member 26Y and the second screw member 32Y as the agitating / conveying members are respectively provided with a rod-like rotary shaft member whose both ends are rotatably supported by a bearing (not shown), and a spiral projection on the peripheral surface thereof. And a spiral blade. Then, as it is driven to rotate by a driving means (not shown), the Y developer is conveyed in the rotation axis direction by the spiral blade.

  In the first transport chamber in which the first screw member 26Y is accommodated, the Y developer is transported from the near side to the far side in the direction orthogonal to the drawing surface as the first screw member 26Y is driven to rotate. . And if it conveys to the edge part vicinity of the back | inner side of casing 21Y, it will approach into a 2nd conveyance chamber via the opening which is not provided in the partition wall.

  The above-described developing unit 23Y is formed above the second transfer chamber in which the second screw member 32Y is accommodated, and the second transfer chamber and the developing unit 23Y communicate with each other in the entire area of the opposing part. ing. As a result, the second screw member 32Y and the developing sleeve 24Y disposed obliquely above the second screw member 32Y face each other while maintaining a parallel relationship. In the second transport chamber, the Y developer is transported from the back side to the near side in the direction orthogonal to the drawing sheet as the second screw member 32Y is driven to rotate. In this transport process, the Y developer around the rotation direction of the second screw member 32Y is appropriately pumped up to the developing sleeve 24Y, and the developed Y developer is appropriately collected from the developing sleeve 24Y. Then, the Y developer transported to the vicinity of the near end of the second transport chamber in the drawing returns to the first transport chamber through an opening (not shown) provided in the partition wall.

  A toner concentration detection sensor 45Y as a toner concentration detection means including a magnetic permeability sensor is fixed to the lower wall of the first transfer chamber, and the toner concentration of the Y developer conveyed by the first screw member 26Y is lowered. And outputs a voltage according to the detection result. A control unit (not shown) replenishes an appropriate amount of Y toner into the first transfer chamber by driving a Y toner supply device (not shown) as necessary based on the output voltage value from the toner concentration detection sensor 45Y. As a result, the toner concentration of the Y developer, which has been lowered with the development, is recovered.

  The Y toner image formed on the photoreceptor 11Y is primarily transferred onto the intermediate transfer belt 51 at a Y primary transfer nip described later. The transfer residual toner that has not been primarily transferred onto the intermediate transfer belt 51 adheres to the surface of the photoreceptor 11Y after passing through the primary transfer process.

  The drum cleaning device 14Y cantilever-supports a cleaning blade 15Y made of, for example, polyurethane rubber, and the free end thereof is brought into contact with the surface of the photoreceptor 11Y. In addition, the brush tip side of the brush roller 16Y, which includes a rotating shaft member that is driven to rotate by a driving means (not shown) and an infinite number of conductive brushes erected on the peripheral surface thereof, is brought into contact with the photoreceptor 11Y. Yes. The transfer residual toner is scraped off from the surface of the photoreceptor 11Y by the cleaning blade 15Y and the brush roller 16Y. A cleaning bias is applied to the brush roller 16Y via a metal electric field roller 17Y that is in contact with the brush roller 16Y, and the tip of the scraper 18Y is pressed against the electric field roller 17Y. The transfer residual toner scraped off from the photoconductor 11Y by the cleaning blade 15Y and the brush roller 16Y passes through the brush roller 16Y and the electric field roller 17Y, and then is scraped off from the electric field roller 17Y by the scraper 18Y and is placed on the recovery screw 19Y. Fall. Then, after the recovery screw 19Y is driven to rotate, the recovery screw 19Y is discharged out of the casing, and then returned to the developer transport device 22Y via a toner recycling transport means (not shown).

  The surface of the photoreceptor 11Y from which the transfer residual toner has been cleaned by the drum cleaning device 14Y is neutralized by the neutralizing device 13Y including a neutralizing lamp and then uniformly charged again by the charging member 14Y.

  The potential of the non-image portion of the photoreceptor 11Y that has passed the optical writing position by the writing light L is detected by the potential sensor 49Y, and the detection result is sent to a control unit (not shown).

  Although the Y process unit 10Y has been described in detail, the process units (10C, M, K) of other colors have the same configuration as that of Y except that the color of the toner to be used is different. .

  In FIG. 2 shown above, the photoconductors 11Y, 11C, 11M, and 11K of the process units 10Y, 10C, 10M, and 10K are in contact with the upper stretched surface of the intermediate transfer belt 51 that is moved endlessly in the clockwise direction. Rotating to form primary transfer nips for Y, C, M, and K. On the back side of the primary transfer nips for these Y, C, M, and K, the above-described primary transfer rollers 55Y, 55C, 55M, and 55K are in contact with the back surface of the intermediate transfer belt 51. A primary transfer bias having a polarity opposite to the charging polarity of the toner is applied to each of the primary transfer rollers 55Y, 55C, 55M, 55K by a bias supply unit (not shown). Due to this primary transfer bias, a primary transfer electric field is formed in the primary transfer nips for Y, C, M, and K to electrostatically move the toner from the photoreceptor side to the belt side. The Y, C, M, and K toner images formed on the photoreceptors 11Y, 11C, 11M, and 11K are primary for Y, C, M, and K as the photoreceptors 11Y, 11C, 11M, and 11K rotate. When entering the transfer nip, primary transfer is performed by sequentially superimposing on the intermediate transfer belt 51 by the action of the primary transfer electric field and nip pressure. As a result, a four-color superimposed toner image (hereinafter referred to as a four-color toner image) is formed on the front surface (loop outer peripheral surface) of the intermediate transfer belt 51. Instead of the primary transfer rollers 55Y, 55C, 55M, 55K, a conductive brush to which a primary transfer bias is applied, a non-contact type corona charger, or the like may be employed.

  An optical sensor unit 69 is disposed on the right side of the K process unit 10K in the drawing so as to face the front surface of the intermediate transfer belt 51 with a predetermined gap. The optical sensor unit 69 outputs a voltage corresponding to a toner adhesion amount per unit area with respect to a later-described reference toner patch image transferred to the intermediate transfer belt 51.

  A secondary transfer roller 56 is disposed below the intermediate transfer belt 51. The secondary transfer roller 56 abuts against the front surface of the intermediate transfer belt 51 while being driven to rotate counterclockwise in the drawing by a driving means (not shown). A secondary transfer nip is formed in contact therewith. A secondary transfer backup roller 53 wraps around the intermediate transfer belt 51 on the back side of the secondary transfer nip.

  A secondary transfer bias having the same polarity as the toner charging polarity is applied to the secondary transfer backup roller 53 by a secondary transfer power source (not shown). On the other hand, the secondary transfer roller 56 that is a contact member that is in contact with the front surface of the belt and forms a secondary transfer nip is grounded. As a result, a secondary transfer electric field is formed between the secondary transfer backup roller 53 and the secondary transfer roller 56. The four-color toner image formed on the front surface of the intermediate transfer belt 51 enters the secondary transfer nip as the intermediate transfer belt 51 moves endlessly.

  In FIG. 1 described above, the paper feeding device 200 is fed with a paper feeding cassette 201 for storing the recording paper P, and a paper feeding roller 202 for feeding the recording paper P stored in these paper feeding cassettes 201 out of the cassette. A plurality of separation roller pairs 203 for separating the recording paper P one by one, a plurality of conveyance roller pairs 205 for conveying the separated recording paper P along the delivery path 204, and the like are provided. The sheet feeding device 200 is disposed directly below the printer unit 1 as shown in the figure. The feeding path 204 of the paper feeding device 200 is connected to the paper feeding path 70 of the printer unit 1. As a result, the recording paper P delivered from the paper feed cassette 201 of the paper feed device 200 is sent into the paper feed path 70 of the printer unit 1 via the feed path 204.

  Near the end of the paper feed path 70 of the printer unit 1, a registration roller pair 71 is disposed as a feeding means, and the recording paper P sandwiched between the rollers is converted into a four-color toner image on the intermediate transfer belt 51. The sheet is fed into the secondary transfer nip at a timing that can be synchronized. In the secondary transfer nip, the four-color toner images on the intermediate transfer belt 51 are collectively transferred to the recording paper P due to the influence of the secondary transfer electric field and the nip pressure, and combined with the white color of the recording paper P, Become. The recording paper P on which the full-color image is formed in this way is separated from the intermediate transfer belt 51 when discharged from the secondary transfer nip.

  On the left side of the secondary transfer nip in the figure, a conveyor belt unit 75 is provided that moves the endless paper conveyor belt 76 endlessly in the counterclockwise direction in the figure while being stretched by a plurality of stretching rollers. . The recording paper P separated from the intermediate transfer belt 51 is transferred to the upper stretched surface of the paper conveying belt 76 and conveyed toward the fixing device 80.

  The recording paper P sent into the fixing device 80 is sandwiched in a fixing nip formed by a heating roller 81 containing a heat source such as a halogen lamp (not shown) and a pressure roller 82 pressed toward the heating roller 81. The full color image is sent to the outside of the fixing device 80 while being fixed on the surface by being heated while being pressurized.

  On the surface of the intermediate transfer belt 51 after passing through the secondary transfer nip, a slight amount of secondary transfer residual toner that has not been transferred to the recording paper P adheres. The secondary transfer residual toner is removed from the belt by a belt cleaning device 57 that is in contact with the front surface of the intermediate transfer belt 51.

  A switchback device 85 is disposed below the fixing device 80. When the recording paper P discharged from the fixing device 80 reaches the conveyance path switching position by the swingable switching claw 86, depending on the swing stop position of the switching claw 86, the paper discharge roller pair 87 or the switchback device. Sent to 85. When the paper is sent toward the paper discharge roller pair 87, the paper is discharged to the outside of the apparatus and then stacked in the form of the paper discharge tray 3.

  On the other hand, when it is sent toward the switchback device 85, it is turned upside down by the switchback conveyance by the switchback device 85 and then conveyed toward the registration roller pair 71 again. Then, it again enters the secondary transfer nip, and a full-color image is formed on the other side.

  The recording paper P manually fed onto the manual feed tray 2 provided on the side surface of the housing of the printer unit 1 passes through the manual feed roller 72 and the manual separation roller pair 73 and then toward the registration roller pair 71. Sent.

  When copying a document with the copying machine according to the present embodiment, first, the document is set on the document table 401 of the automatic document feeder 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass 301 of the scanner 300, and the automatic document feeder 400 is closed and pressed. Thereafter, when a start switch (not shown) is pressed, when the document is set on the automatic document feeder 400, the document is sent into the contact glass 301. Then, the scanner 300 is driven and reading scanning by the first traveling body 303 and the second traveling body 304 is started. At substantially the same time, driving of the transfer unit 50 and each color process unit 10Y, C, M, K starts. Furthermore, the feeding of the recording paper P from the paper feeding device 200 is also started. When recording paper P not set in the paper feed cassette 201 is used, the recording paper P set on the manual feed tray 2 is sent out.

  A control unit as a control unit (not shown) of the printer unit 1 of the copying machine includes a CPU (Central Processing Unit), a ROM (Read Only Memory) as a data storage unit, a RAM (Random Access Memory), an I / O interface, and the like. It is configured. Based on the control program stored in the ROM, the driving of various devices in the printer unit 1 is controlled.

  At one end portion in the width direction of the intermediate transfer belt 51, a K-color toner patch pattern is formed at a predetermined timing. The K color toner patch pattern is composed of a plurality of K reference toner patch images arranged at a predetermined interval in the belt moving direction. Further, Y, M, and C toner patch patterns are formed at predetermined timings on the other end in the width direction of the intermediate transfer belt 51, respectively. These toner patch patterns are also composed of a plurality of Y, M, and C toner patch images arranged at predetermined intervals in the belt moving direction. In this copying machine, each toner patch pattern is composed of seven reference toner patch images, but the number of reference toner patch images constituting the toner patch pattern may be larger or smaller. Hereinafter, the three colors Y, M, and C are collectively referred to as color colors.

  The optical sensor unit 69 previously shown in FIG. 2 emits light (not shown) that emits light toward the belt surface near one end in the width direction of the intermediate transfer belt 51 and specularly reflected light that is specularly reflected on the belt surface. A first optical sensor having a regular reflection light receiving element (not shown) that receives light is included. In addition, near the other end in the width direction of the intermediate transfer belt 51, a light emitting element (not shown) that emits light toward the belt surface and a diffusion light receiving element (not shown) that receives diffusely reflected light diffusely reflected on the belt surface are provided. And a second optical sensor.

  Each K reference toner patch image in the K color toner patch pattern formed at one end of the intermediate transfer belt 51 in the width direction is directly below the first optical sensor of the optical sensor unit 69 as the belt moves endlessly. If it moves, the output voltage value from a 1st optical sensor will fall remarkably. This is because the light emitted from the light emitting element of the first optical sensor is blocked by the K toner layer of the K reference toner patch image and hardly reflects regularly on the belt surface. The output voltage value from the first optical sensor at this time is a value corresponding to the K toner adhesion amount (K image density) per unit area with respect to the K reference toner patch image. And the control part can grasp | ascertain the K toner adhesion amount with respect to a K reference | standard toner patch image based on the output voltage value from a 1st optical sensor.

  Further, the Y, M, and C reference toner patch images in the color toner patch pattern formed on the other end in the width direction of the intermediate transfer belt 51 are transferred to the second sensor of the optical sensor unit 69 as the belt moves endlessly. When moving directly below the optical sensor, the output voltage value from the second optical sensor rises significantly. This is because the light emitted from the light emitting element of the second optical sensor is diffusely reflected on the surface of the Y, M, C toner layer of the Y, M, C reference toner patch image and then diffused reflected light as described above. This is because the light is received. The output voltage value from the second optical sensor at this time is a value corresponding to the Y, M, C toner adhesion amount (Y, M, C image density) per unit area with respect to the Y, M, C reference toner patch image. Become. Then, the control unit can grasp the Y, M, and C toner adhesion amounts with respect to the Y, M, and C reference toner patch images based on the output voltage value from the second optical sensor.

  The printer unit 1 supplies Y, M, C, and K toners (not shown) to the developing devices 20Y, M, C, and K of the process units 10Y, M, C, and K, respectively. A toner replenishing device for K is provided. In addition, Y, M, C, and K toner cartridges (not shown) that individually store replenishment Y, M, C, and K are removably attached to the printer unit 1.

  The developing devices 20Y, M, C, and K are toners for Y, M, C, and K, each of which includes a magnetic permeability sensor that detects Y, M, C, and K toner images of the Y, M, C, and K developers inside. It has a density detection sensor. The control unit stores Y-Vtref, M-Vtref, C-Vtref, and K-Vtref, which are output control target values of the toner density detection sensors for Y, M, C, and K, in the RAM. Based on these Vtref and the output voltage Vt from the Y, M, C, and K toner density detection sensors, the driving of the toner supply device for Y, M, C, and K is controlled. Specifically, when the toner concentration of the developer decreases due to the consumption of the toner in the developer accompanying the developing operation, the output voltage value from the toner concentration detection sensor increases. Therefore, ΔT (Vtref−Vt), which is the difference between Vtref and the output voltage Vt from the toner density detection sensor, is calculated at a predetermined timing. If the calculation result is a positive value, the toner density of the developer is calculated. Therefore, the toner replenishing device is not driven. On the other hand, when ΔT is a negative value, the toner replenishing device is driven for a time corresponding to the value, thereby restoring the toner density of the developer to a predetermined control target value.

Next, a characteristic configuration of the copying machine will be described.
FIG. 4 is an enlarged configuration diagram showing the developing device 20Y for Y. Although not shown in FIG. 3 for the sake of convenience, the developing device 20Y has an initial agent storage portion 27Y that stores a Y-color initial agent above the developer transport device 22Y. The initial agent storage portion 27Y and the developer transport device 22Y communicate with each other through an initial agent charging opening. However, in the developing device 20Y in the initial state, the initial agent charging opening is closed by a sealing seal (not shown). Prior to mounting a new Y process unit (10Y) in the printer unit 1, the user pulls out the sealing seal from the developing device 20Y, so that the initial agent storage unit 27Y and the developer transport device 22Y. To communicate with. As a result, the initial agent can drop from the initial agent container 27Y to the developer conveying device 22Y.

The toner manufacturer's test shows that the Y, M, C, and K toners used in this printer vary from product to product in a range of 0.38 ± 0.04 [g / cm ³ ]. Is previously determined. That is, the standard value of the loose apparent density of the toner is 0.38 [g / cm ³ ]. The loose apparent density is measured as follows. That is, 10 [g] of toner is put in a 50 [ml] graduated cylinder, and then covered and shaken 50 times. The scale is read after opening the lid and allowed to stand for 10 minutes, and the ratio to the measured toner amount is calculated to obtain the loose apparent density.

In FIG. 2 described above, the toner density detection sensors of the developing devices 20Y, 20M, 20C, and 20K each have an IC chip (not shown), in which sensor sensitivity information is stored in a machine-readable manner. ing. The sensitivity information is a function representing a graph of the rate of change of the output voltage Vt accompanying the change of the magnetic permeability as shown in FIG. This function exhibits the same magnetic permeability as a developer containing toner having a loose apparent density of 0.38 [g / cm ³ ], which is a standard value, in a concentration of 4, 7, 10 [wt%] 3 Each sensor product is constructed based on the result of actually measuring the output voltage Vt for one magnetic sample.

  The initial agent container 27Y of the developing device 20Y shown in FIG. 4 is detachable from the developing device main body. A nonvolatile RAM (not shown) is fixed to the outer wall of the initial agent containing portion 27Y having such a configuration. In this nonvolatile RAM, an initial agent container ID number that also functions as a product ID of the developing device and loose apparent density information are stored as electronic data in a machine-readable manner. This loose apparent density information indicates the loose apparent density of the toner in the initial agent sealed in the initial agent container 27Y, and the actual value of the loose apparent density of the toner is stored in the non-volatile RAM before shipment from the factory. It is remembered. The toner concentration of the initial agent is adjusted to 7 [wt%].

On the other hand, the control unit of the printer unit 1 stores correction data in a ROM as correction data storage means. This correction data is based on the amount of deviation from the standard value (0.38 g / cm ³ ) of the loose apparent density of the toner in the initial agent, and the upper limit value of Vtref (considered as the toner density). In this case, the lower limit value is corrected. Specifically, a good correlation is established between the above-described deviation amount and the deviation amount from the appropriate value of Vtref. The correlation is generally constant regardless of the product lot of the toner or toner density detection sensor. The correction data is constructed based on the result of examining the correlation by an experiment in advance. This is data for correcting the reference value of the upper limit value of Vtref to an appropriate value that does not cause carrier adhesion from the deviation amount from the standard value of the loose apparent density of the toner contained in the initial agent.

FIG. 5 is a graph illustrating an example of correction data stored in the ROM of the control unit of the printer unit 1. The horizontal axis of this graph represents the amount of deviation from the standard value (0.38 g / cm ³ ) of the loose apparent density of the toner contained in the initial agent. This deviation amount can be easily obtained by subtracting the loose apparent density of the toner in the initial agent stored in the non-volatile RAM of the initial agent container of the developing device from the standard value of the loose apparent density. .

  The vertical axis of the graph represents the shift amount from the appropriate value of the upper limit value of Vtref (lower limit value of toner density). The shift amount corresponding to the above-described shift amount is specified based on this graph, and the upper limit value of Vtref is corrected to an appropriate value that does not cause carrier adhesion by adding the specified result to the reference value of the upper limit value. can do. In addition, although the example which memorize | stored the graph (function which shows) the relationship between deviation | shift amount and shift amount as correction | amendment data was demonstrated, the relationship between the appropriate value of the upper limit of Vtref and a loose apparent density is shown. Other types such as graphs may be stored.

  When the process unit 1Y is attached to the printer unit 1, a terminal (not shown) provided on the housing of the developing device 20Y and a terminal (not shown) provided on the printer unit main body come into contact with each other. Then, communication between the control unit of the printer unit 1 and the nonvolatile RAM of the initial agent storage unit 27Y of the developing device 20Y can be performed via the contacts of both terminals. The process units 1M, C, and K have the same configuration as the process unit 1Y.

  The control unit detects that a new one has been set for each of the developing devices 20Y, 20M, 20C, and 20K by the following processing. That is, when the process unit is taken out from the printer unit, communication with the nonvolatile RAM fixed to the initial agent container of the developing device of the process unit becomes impossible. Further, when the process unit is mounted on the printer unit, communication with the nonvolatile RAM of the developing device of the process unit, which has been impossible until now, becomes possible. The control unit detects attachment / detachment of the process unit based on the availability of such communication. When mounting of a process unit is detected, for the initial agent container ID stored in the nonvolatile RAM of the developing device in the process unit, does the value before mounting detection match the value after mounting detection? Judge whether or not. Then, based on the fact that they do not match, it is detected that the process unit has been exchanged.

  In addition, when the control unit detects replacement of a process unit, the control unit performs initial adjustment processing after replacement for the process unit. FIG. 6 is a flowchart showing a control flow of the initial adjustment process after the replacement. When the replacement of the process unit is detected (Y in Step 1; hereinafter, Step is referred to as S), first, the sensitivity stored in the IC chip of the toner concentration detection sensor mounted on the developing device of the process unit. Information is read (S2). Then, the upper limit value (lower limit value of toner density) and lower limit value (upper limit value of toner density) of Vtref of the toner density detection sensor are read (S3). Next, driving of the developer conveying device of the developing device is started (S4). As a result, the initial agent in the initial agent container of the developing device starts to be gradually fed into the developer conveying device by the rotation of the screw member of the developer conveying device. When a predetermined time has elapsed from the start of driving of the developer conveying device (Y in S5), all of the initial agent in the initial agent accommodating portion moves into the developer conveying device and the initial agent is stirred by the screw member. The toner inside is frictionally charged to some extent. Thereafter, by adjusting the control voltage to the toner concentration detection sensor, the output from the toner concentration detection sensor whose initial agent is to be tested is calibrated to 2.7 [V] which is the standard output value (S6).

  When the calibration of the toner density detection sensor is completed, the loose apparent density information stored in the nonvolatile RAM of the initial agent container of the developing device is read (S7) and then included in the initial agent. A density deviation amount, which is a deviation amount from the standard value of the loose toner apparent density, is obtained (S8). Then, after correcting the upper limit value of Vtref (lower limit value of toner density) based on the density deviation amount and the correction data described above (S9), an initial process control process is performed (S10).

  The initial process control process will be described in detail below. FIG. 7 is a flowchart showing the processing contents of the initial process control processing. In the initial process control process, first, a pattern forming process for forming a toner patch pattern on the surface of the photoconductor of the replaced process unit is performed (S10a). The formed toner patch pattern is composed of seven reference toner patch images arranged at predetermined intervals on the peripheral surface of the photoreceptor, and each reference toner patch image is developed under conditions of different development biases Vb. . In the pattern forming process, the photosensitive member is always uniformly charged with a constant charge amount, and the exposure amount at the time of optical writing when obtaining a patch latent image for the reference toner patch image is also controlled to be constant. . Therefore, the difference in the development bias Vb in each reference toner patch image indicates the difference in development potential, which is the potential difference between the electrostatic latent image and the development bias Vb. As the development potential increases, the toner adhesion amount (image density) per unit area of the toner image increases. The seven reference toner patch images in the toner patch pattern are developed with a larger development bias Vb (development potential) as the order of formation becomes the first, second,... It gets bigger. The fourth reference toner patch image in the order of formation is developed with a predetermined standard development bias Vb. The toner patch pattern developed on the surface of the photoreceptor is transferred to the intermediate transfer belt 51.

  When the pattern forming process is completed, a development γ calculation process is performed (S10b). In this development γ calculation process, first, the amount of toner attached to seven reference toner patch images in the toner patch pattern transferred onto the intermediate transfer belt 51 is detected by the first optical sensor or the second optical sensor of the optical sensor unit 69, respectively. Is done. Next, based on the development potential corresponding to each of the seven reference toner patch images and the detection result of the toner adhesion amount corresponding to each of the seven reference toner patch images, the relationship between the development bias Vb and the toner adhesion amount is determined. The development γ as a function shown is obtained by the least square method.

  When the development γ calculation process is performed in this way, next, an appropriate development bias that is a development bias Vb for obtaining a predetermined target toner adhesion amount (image density) is calculated based on the development γ. (S10c). Here, by performing the subsequent development operation under the conditions of the calculated appropriate development bias, it is possible to obtain the target toner adhesion amount without changing the toner concentration of the initial agent. However, at the time of initial printing, development is performed with the development bias Vb as close to the standard development bias as possible (the development bias when the fourth reference toner patch image is formed). It is preferable for convenience. Therefore, it is determined whether or not the difference between the appropriate development bias and the standard development bias is within a predetermined range (S10d). If it is not within the predetermined range (N in S10d), after the developing bias condition is changed (S10e), the pattern forming process is performed again. At this time, each of the seven reference toner patch images is developed with a development bias Vb different from that in the previous pattern formation process. As a result, the fourth reference toner patch image is developed with the development bias Vb having the same value as the previously calculated appropriate development bias. On the other hand, if the difference between the appropriate development bias and the standard development bias is within a predetermined range (Y in S10d), the toner adhesion amount with respect to the fourth reference toner patch image becomes the target value or the toner density detection sensor The toner density adjustment process and the pattern forming process are repeated until the output voltage Vt becomes the same value as the upper limit value or until the output voltage Vt becomes the same value as the lower limit value (N in S10f → S10g → N in S10h) → N in S10i → S10a).

  In the toner density adjustment process (10f), when the toner adhesion amount with respect to the fourth reference toner patch image is smaller than the target value, the toner is supplied to the initial agent by driving the toner supply device. However, when the output voltage Vt of the toner concentration detection sensor is the same value as the lower limit value or smaller than the lower limit value, the toner supply is stopped. Further, when the toner adhesion amount with respect to the fourth reference toner patch image is larger than the target value, the predetermined toner forcible consumption image is cleaned on the photosensitive member while being cleaned by the drum cleaning device. The toner in the initial agent is forcibly consumed. However, when the output voltage Vt of the toner density detection sensor is the same value as the upper limit value or larger than the upper limit value, the forced consumption of toner is stopped. In most cases, toner is forcibly consumed rather than toner replenished. The toner in the initial agent is left in the initial agent container at least several months after shipment from the factory, so that it has almost lost its charge. This is because there are many cases.

  When the adjustment of the toner density of the initial agent is properly completed, the control target value Vtref of the output voltage Vt of the toner density detection sensor is set to the same value as the output voltage Vt at that time (S10j).

  In the copying machine configured as described above, the upper limit value of Vtref for limiting the lower limit density of the toner density of the initial agent based on the apparent looseness density of the toner in the initial agent and the above-described correction data, Correct to a value that does not cause carrier adhesion. As a result, the initial agent is adjusted to a toner concentration suitable for the environment and the initial printing is performed, and the occurrence of carrier adhesion during the initial printing due to the variation in the apparent density of the loose toner contained in the initial agent is suppressed. Can do.

  Although an example in which the loose apparent density information of the toner in the initial agent is stored in the nonvolatile RAM fixed to the initial agent container of the developing device has been described, the initial agent carrier is used instead of the loose apparent density information. You may memorize | store density (bulk density) information. In this case, data for correcting the upper limit value of Vtref based on the shift amount of the carrier density information may be stored in the ROM of the control unit as the correction data.

  Further, in this copying machine, the Y, M, C, and K toner cartridges that individually store Y, M, C, and K toners also store information on the apparent density of toner looseness therein. A RAM is provided. In the toner density adjustment process (S10f), when toner is replenished in the initial agent, the replenishment amount, the looseness density information of the toner in the initial agent, and the looseness density of the toner in the toner cartridge. The control unit is configured to appropriately correct the lower limit value of Vtref based on the information.

Next, modified examples of the copying machine according to the embodiment will be described. Unless otherwise specified below, the configuration of the copying machine according to each modification is the same as that of the embodiment.
[First Modification]
In the copying machine according to the first modification, as the developing devices 20Y, 20M, 20C, and 20K of the respective colors, the loose density density information of the toner in the initial agent is attached to the housing of the developing device as visible characters and symbols. Something is used. For example, it is attached with a number such as “0.39” that can be visually recognized by humans. The numerical value indicating the loose apparent density may be directly formed on the resin-made casing as a laser marker by laser processing, or may be attached to the casing by sticking a seal on which the numerical values are printed.

  The printer unit 1 includes unit attachment / detachment detection sensors for detecting attachment / detachment operations for the process units 1Y, M, C, and K of the respective colors. This unit attachment / detachment detection sensor only detects attachment / detachment of a process unit and cannot detect whether or not the unit has been replaced.

  When the unit attachment / detachment detection sensor detects the attachment / detachment operation of one of the process units, the control unit displays on the display unit consisting of a display, etc., not shown, `` Did you replace the developing device for the color process unit with a new one? A message for inquiring whether or not the developing device of the detached unit is to be replaced is displayed. Then, based on the display, when the information that the user has exchanged is input to the data input operation unit such as a numeric keypad, “Please enter the number written on the case of the developing device” etc. A message prompting the user to input the loose apparent density is displayed on the display unit. When the user inputs the loose apparent density information based on this display, the control unit can acquire the loose apparent density information. That is, the data input operation unit functions as data input means for acquiring loose apparent density information represented by characters and symbols by an input operation by an operator. When the loose apparent density information is input, the control unit performs calibration of the sensor, correction of the upper limit value of Vtref, initial process control processing, and the like in the same manner as in the embodiment.

[Second Modification]
In the copying machine according to the second modification, as the developing devices 20Y, 20M, 20C, and 20K of each color, the loose apparent density information of the toner in the initial agent is used as a barcode as a visually recognizable code pattern. The ones attached to are used. For example, it is a barcode indicating a number such as “0.39” that can be visually recognized by a human. Such a barcode may be directly formed on a resin casing as a laser marker by laser processing, or may be attached to the casing by sticking a sticker on which a numerical value is printed.

  The printer unit 1 includes a unit attachment / detachment detection sensor similar to the copying machine according to the first modification. When the unit attachment / detachment detection sensor detects the attachment / detachment operation of any of the process units, the control unit prompts the scanner 300 to read the barcode image attached to the developing device of the process unit. Is displayed on the display. When the user places the developing device on the contact lens of the scanner 300 according to this message, presses the copy start button, and reads the barcode image by the scanner 300, the barcode recognition unit (not shown) of the printer unit 1 is known. The number indicated by the barcode is analyzed according to the same principle as the barcode reader of, and the result is sent to the control unit. As a result, the control unit can acquire the loose apparent density information. That is, the combination of the scanner 300 and the above-described barcode recognition unit functions as a reading conversion unit that reads a barcode image that is a code pattern and then converts it into loose apparent density information based on the reading result. . When the loose apparent density information is input, the control unit performs calibration of the sensor, correction of the upper limit value of Vtref, initial process control processing, and the like in the same manner as in the embodiment.

  Up to this point, an example of a copying machine that forms a multicolor image by a plurality of process units has been described. The present invention can also be applied to an image forming apparatus that obtains a multicolor image by superimposing and transferring toner images of different colors sequentially obtained on a body to an intermediate transfer body. The present invention can also be applied to an image forming apparatus that forms only a monochrome image.

  As described above, in the copying machine according to the embodiment, the initial agent storage unit that stores the initial agent is detachably attached to the developing device main body, and the nonvolatile RAM as the density information storage unit is provided in the initial agent storage unit. . In such a configuration, due to the deterioration of the magnetic carrier of the developing device used to some extent, after the developer in the developing device is taken out and discarded, a new initial agent container is attached to the developing device and newly installed. Even when an initial agent is set, the upper limit value of Vtref (lower limit value of toner concentration) can be corrected to an appropriate value that does not cause carrier adhesion based on the toner loose apparent density information of the initial agent. it can.

  Further, in the copying machine according to the embodiment, a photosensitive member as a latent image carrier for holding a latent image, an optical writing unit 68 as a latent image forming unit for forming a latent image on the photosensitive member, toner and a magnetic carrier. Developer conveying device as developer accommodating portion for containing developer contained therein, toner concentration detecting sensor as toner concentration detecting means for detecting toner concentration of developer inside thereof, and developer conveying device carried on own surface A developing device having a developing sleeve that is a developer carrying member that develops a latent image on the photosensitive member with the developer inside, a toner replenishing device that is a toner replenishing unit that replenishes toner to the developer conveying device, and a developing device. By developing a predetermined toner consumption image on the photoconductor based on the detection result of the toner concentration detection sensor that targets the initial developer, which is a new developer, a predetermined lower limit Degrees and a control unit for performing the initial toner concentration lowering treatment serving toner density adjustment processing for reducing the toner density of the initial agent a limit (the upper limit value of the Vtref). Then, a control unit that is a reading unit that mechanically reads loose apparent density information stored in the nonvolatile RAM, and an upper limit value of Vtref that is a lower limit value of a toner density control target based on the loose apparent density of toner in the initial agent. And a ROM as correction data storage means for storing correction data for correcting the upper limit value of Vtref (toner density value) based on the loose apparent density information obtained by the control unit and the correction data. The control unit is configured to perform a process of correcting the lower limit value. In such a configuration, as a new developing device (a process unit on which a new developing device is mounted) is attached to the printer unit 1, the information on the apparent density of loose toner in the initial agent can be automatically acquired by the control unit. .

  Further, in the copying machine according to the embodiment and the copying machine according to each modification, a sensitivity storage unit that stores, as a toner density detection sensor, sensitivity information that is a rate of change of an output signal with respect to a change in toner density in a machine-readable manner. And an upper limit value of Vtref (lower limit value of toner concentration) based on the sensitivity information stored in the IC chip and the apparent looseness density information of the toner in the initial agent. ) Is configured so as to correct. In such a configuration, the upper limit value of Vtref can be set to an appropriate value according to the sensitivity specific to each toner density detection sensor.

  Further, in the copying machine according to the first modification, as the developing device, the slack apparent density information attached to the housing of the developing device as visible characters or symbols is used, and input by the operator as information acquisition means A data input operation unit is used as data input means for acquiring characters and symbols by operation. In such a configuration, the loose apparent density of the initial agent can be acquired by prompting the operator to perform an input operation.

  Further, in the copying machine according to the second modification, as the developing device, a barcode attached to the housing of the developing device as a barcode pattern as a visible code pattern is used as the developing device, and a barcode is used as an information acquisition unit. Read conversion means (scanner 300 and bar code recognition unit) that converts the image into slack apparent density information based on the read result. In such a configuration, the loose apparent density of the initial agent can be acquired without forcing the user to read and input numbers and symbols.

  In addition, in the copying machine according to the first modification or the second modification, when characters, symbols, or barcodes are attached to the housing of the developing device as laser markers by laser processing, a seal on which loose apparent density information is printed It is possible to avoid the loss of loose apparent density information due to peeling.

  Further, in the copying machine according to the first modification or the second modification, when a sticker with characters, symbols, or a barcode is attached to the housing of the developing device, the used developing device housing By removing the seal, new loose apparent density information can be easily attached to the recycle developing apparatus obtained by turning the casing to the recycle process after cleaning, by reattaching the seal.

1 is a schematic configuration diagram showing a copier according to an embodiment. FIG. 3 is a partially enlarged configuration diagram illustrating a part of an internal configuration of a printer unit in the copier. FIG. 3 is an enlarged configuration diagram illustrating a Y process unit of the printer unit together with an intermediate transfer belt. FIG. 3 is an enlarged configuration diagram showing a developing device of the process unit. 6 is a graph showing an example of correction data stored in a ROM of a control unit of the printer unit. The flowchart which shows the control flow of the post-exchange initial adjustment process implemented by the control part. The flowchart which shows the processing content of the initial stage process control process implemented by the control part. 6 is a graph showing an example of a relationship between an output voltage Tt of a toner concentration detection sensor including a magnetic permeability sensor and a toner concentration of a developer. The graph which shows the same relationship after calibrating a toner concentration detection sensor. The graph which shows the change of the inclination of the relationship by the variation in the loose apparent density of the toner contained in an initial agent.

Explanation of symbols

1Y, M, C, K: Process unit 11Y, M, C, K: Photoconductor (latent image carrier)
20Y: Development device 22Y: Developer transport device (developer container)
24Y: Development sleeve (developer carrier)
27Y: Initial agent container 45Y: Toner concentration detection sensor (toner concentration detection means)
68: Optical writing unit (latent image forming means)

Claims (9)

A developer containing portion that contains a developer containing toner and a magnetic carrier; a toner concentration detecting means for detecting the toner concentration of the developer in the developer containing portion; and a developer containing portion carried on the surface of the developer containing portion. In a developing device having a developer carrier that develops a latent image on the latent image carrier with a developer,
The carrier density information in the initial agent, which is a new developer set in the developing device prior to factory shipment, or the loose density information of the toner in the initial agent is attached to the housing of the developing device, or the A developing apparatus comprising a density information storage means for storing carrier density information or loose apparent density information as electronic data. The developing device according to claim 1.
An initial agent accommodating portion for accommodating the initial agent is provided detachably with respect to the developing device main body, and the carrier density information or the loose apparent density information is attached to the initial agent accommodating portion, or the density information storage means is A developing device characterized in that it is provided in an initial agent container. A latent image carrier for carrying a latent image;
Latent image forming means for forming a latent image on the latent image carrier;
A developer container that contains a developer containing toner and a magnetic carrier, a toner concentration detection means for detecting the toner concentration of the developer in the developer container, and development in the developer container carried on its own surface A developing device having a developer carrier for developing a latent image on the latent image carrier with an agent;
Toner replenishing means for replenishing the developer container with toner;
While maintaining the state where the output value from the toner concentration detection means for testing the initial agent, which is a new developer set in the developing device, becomes a value on the lower toner concentration side than the predetermined threshold value, An image forming apparatus comprising: a control unit that develops a predetermined toner consumption image on the latent image carrier and performs a process of reducing the toner concentration of the initial agent.
The developing device according to claim 1 or 2 is used as the developing device.
Information acquisition means for acquiring the carrier density information or the loose apparent density information attached to the developing device is provided, or reading means for mechanically reading the loose apparent density information stored in the density information storage means As well as
A correction data storage means for storing correction data for correcting the threshold based on the carrier density of the initial agent or the apparent loose density of the toner in the initial agent;
The control unit is configured to perform the process of correcting the threshold based on the carrier density information or the loose apparent density information obtained by the information acquisition unit or the reading unit and the correction data. An image forming apparatus. The image forming apparatus according to claim 3.
As the toner density detection means, a sensor having a built-in sensitivity storage means for storing the sensitivity information, which is the rate of change of the output signal with respect to the change in the toner density, in a machine-readable manner is used.
An image characterized in that the control means is configured to correct the threshold based on the sensitivity information stored in the sensitivity storage means and the carrier density information or the loose apparent density information. Forming equipment. The image forming apparatus according to claim 3 or 4,
As the developing device, using the carrier density information or the loose apparent density information attached to the housing of the developing device as a visible character, symbol or code pattern,
An image forming apparatus using a data input means for acquiring the character, symbol or code pattern by an input operation by an operator as the information acquisition means. The image forming apparatus according to claim 3 or 4,
As the developing device, using the carrier density information or the loose apparent density information attached to the housing of the developing device as a visible character, symbol or code pattern,
An image characterized in that, as the information acquisition means, read conversion means for reading an image of the character, symbol or code pattern and converting the image into the carrier density information or the loose apparent density information based on the read result is used. Forming equipment. The image forming apparatus according to claim 5 or 6,
An image forming apparatus, wherein the character, symbol, or code pattern is attached to the casing by laser processing. The image forming apparatus according to claim 6 or 7,
An image forming apparatus, wherein a seal with the character, symbol, or code pattern is attached to the casing. A latent image carrier that carries a latent image, a latent image forming unit that forms a latent image on the latent image carrier, a developing device that develops the latent image on the latent image carrier, and toner for the developing device In an image forming apparatus having a toner replenishing means for replenishing, at least the latent image carrier and the developing device are held by a common holding body, and can be integrally attached to and detached from the image forming apparatus main body as one unit. In the configured process unit,
A process unit using the developing device according to claim 1 or 2 as the developing device.

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