JP2012128131A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copying machine capable of obtaining target image density and of suppressing occurrence of scumming, regardless physical properties of toner contained in a toner container 90K.SOLUTION: A non-contact IC chip 95K stored with a density target table, which is toner density information suitable for physical properties of toner contained in a toner container 90K, is disposed on the toner container 90K. Further, a communication substrate for reading and writing the toner density information with respect to the non-contact IC chip 95K is disposed on a toner supplying device for supplying the toner contained in the toner container 90K to a developing device (not illustrated). Furthermore, a controller (not illustrated) is configured so as to perform determining processing for determining a toner density target value of developer in the developing device based on the density target table stored in the non-contact IC chip 95K.

Description

  The present invention replenishes toner to the developing means based on the result of comparison of the density target value with the result of detecting the toner density of the developer in the developing means by the toner density detecting means, and adjusts the toner density of the developer. The present invention relates to an image forming apparatus that is maintained near a density target value.

  Conventionally, as this type of image forming apparatus, the one described in Patent Document 1 is known. This image forming apparatus includes a photosensitive member as a latent image carrier, a developing unit as a developing unit that develops an electrostatic latent image carried on the surface of the photosensitive member, and a toner replenishing device that replenishes toner in the developing unit. Have. The developing device carries the developer containing toner and magnetic carrier on the surface of the rotating developing roller, and conveys it to the developing area where the developing roller and the photoconductor face each other as the developing roller rotates. Then, in the development area, the electrostatic latent image is developed by transferring the toner in the developer to the area where the electrostatic latent image is carried on the surface of the photoreceptor. Further, the developer that has contributed to the development is returned to the developer accommodating portion in the developing device as the developing roller rotates. In the developer accommodating portion, the developer that contributed to the development is returned, so that the toner density of the developer becomes lower than a predetermined density target value. In view of this, the image forming apparatus detects the toner concentration of the developer in the developer accommodating portion by a magnetic permeability sensor serving as a toner concentration detecting means. Then, when the output voltage value from the magnetic permeability sensor that increases the output as the toner density decreases becomes larger than the reference voltage value as the density target value, the toner replenishing device is driven to develop the developing device. The toner is supplied to the agent storage unit. By such toner replenishment control, the toner density is maintained in the vicinity of the density target value, so that the electrostatic latent image is developed at the target development density or the toner adheres to the non-image portion of the photoreceptor. The occurrence of dirt can be suppressed.

  However, in this image forming apparatus, there is a possibility that a target development density may not be obtained or background stains may occur depending on the production lot of toner to be used. Specifically, even if the toners on the market have the same specifications, there are some errors in physical properties such as fluidity and average charge amount if the production lots are different. When the physical properties of the toner differ, the toner density (appropriate toner density) suitable for obtaining a target development density or suppressing the occurrence of background stains also differs. For this reason, depending on the toner production lot, there may be a large difference between the appropriate toner density and the above-mentioned density target value, and there is a possibility that the target development density may not be obtained or background stains may occur. is there.

  The present invention has been made in view of the above background, and an object of the present invention is to obtain a target image density or to prevent scumming regardless of the physical properties of the toner contained in the toner container. An object of the present invention is to provide an image forming apparatus capable of suppressing the occurrence.

In order to achieve the above object, the invention of claim 1 is a development that develops a latent image on a latent image carrier using a latent image carrier that carries a latent image and a developer containing toner and carrier. A toner density detecting means for detecting the toner density of the developer in the developing means, and a toner container configured to contain toner for replenishing the developing means and to be detachable from the image forming apparatus main body. The toner supply means for supplying toner in the toner container to the developing means, and the drive of the toner supply means is controlled based on the result of comparison between the detection result by the toner density detection means and the density target value. In an image forming apparatus comprising a replenishment control means, information on toner density suitable for the physical properties of toner contained in the toner container, or information useful for obtaining the toner density, The replenishment control means is configured to provide information storage means for storing certain appropriate density information in the toner container, and to execute processing for determining the density target value based on the appropriate density information. It is characterized by this.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, when a replacement detection unit that detects replacement of the toner container is provided, and the replacement of the toner container is detected by the replacement detection unit. After that, until the predetermined information exchange timing arrives, the appropriate density information stored in the information storage means of the toner container before the exchange is used, and after the information exchange timing has arrived, The replenishment control unit is configured to perform processing using the information stored in the information storage unit of the replaced toner container as the appropriate density information.
According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, when a replacement detection unit that detects replacement of the toner container is provided, and replacement of the toner container is detected by the replacement detection unit. Thereafter, until the predetermined calculation method change timing arrives, the pre-replacement information which is the appropriate density information stored in the information storage unit of the toner container before the replacement as the density target value and the post-exchange A value calculated based on the post-replacement information which is the appropriate density information stored in the information storage unit of the toner container and the accumulated toner supply amount from the toner container after replacement to the developing unit. On the other hand, after the calculation method change timing has arrived, the concentration target value is calculated based only on the post-exchange information out of the pre-exchange information and the post-exchange information. As the process to implement the use of value, it is characterized in that constitutes the supply control means.
According to a fourth aspect of the present invention, in the image forming apparatus of the third aspect, before the calculation method change timing arrives, based on the accumulated toner replenishment amount, of the total toner amount in the developing unit, An old toner ratio, which is a ratio of old toner replenished from the toner container before replacement, is calculated, and the density target value is calculated based on the calculation result, the information before replacement, and the information after replacement. Thus, the replenishment control means is configured.
According to a fifth aspect of the present invention, in the image forming apparatus of the second aspect, the information exchange timing is determined based on a cumulative toner supply amount from the toner container after the replacement to the developing unit. Further, the replenishment control means is configured.
According to a sixth aspect of the present invention, in the image forming apparatus according to the third or fourth aspect, the calculation method change timing is determined based on a cumulative toner supply amount from the toner container after replacement to the developing unit. As described above, the replenishment control means is configured.
According to a seventh aspect of the present invention, in the image forming apparatus of the sixth aspect, the old toner replenished from the toner container before replacement out of the total amount of toner in the developing means based on the accumulated toner replenishment amount. The replenishment control means is configured to calculate the old toner ratio, which is a ratio of the above, and to execute processing for determining the calculation method change timing based on the calculation result.
The invention according to claim 8 is useful for obtaining an appropriate toner density for each of various environmental conditions as the appropriate density information in the image forming apparatus according to claim 2 or 5 by providing environment detecting means for detecting the environment. The replenishment is performed so that the information storage unit stores the information and periodically updates the concentration target value based on the detection result of the environment detection unit and the appropriate concentration information. The control means is configured.
According to a ninth aspect of the present invention, in the image forming apparatus according to the third, fourth, sixth, or seventh aspect, an environment detecting unit that detects an environment is provided, and the appropriate toner density is set for each of various environmental conditions as the appropriate density information. Information useful for obtaining is stored in the information storage means, and before the calculation method change timing arrives, the concentration target value is detected by the detection result by the environment detection means, the pre-exchange information, and the exchange. While periodically updated to a value calculated based on the post-information and the accumulated toner supply amount, after the calculation method change timing has arrived, the density target value is set to the detection result by the environment detection means and the The replenishment control means is configured to perform a process of periodically updating to a value calculated based on post-exchange information.
According to a tenth aspect of the present invention, in the image forming apparatus according to the eighth or ninth aspect, the updated density target value is lower than the density target value used immediately before the update, and a difference between the two is a predetermined value. And a forced consumption control means for executing a forced consumption process for forming a toner consumption image on the latent image carrier and forcibly consuming the toner when the threshold is exceeded. .
According to an eleventh aspect of the present invention, in the image forming apparatus according to the tenth aspect, the updated density target value is lower than the density target value used immediately before the update, and a difference between the two is a predetermined first. If the value is between the first threshold value and the second threshold value (first threshold value <second threshold value) and the image forming operation is performed at the time of update, the toner consumption image is stored in the latent image carrier. The compulsory consumption control means is configured to perform the process of forming in the inter-paper correspondence area.
According to a twelfth aspect of the present invention, in the image forming apparatus of the eleventh aspect, the updated density target value is lower than the density target value used immediately before the update, and the difference between the two is the second difference. The forced consumption control means is configured to perform processing for temporarily suspending the image forming operation and forming the toner consuming image when the image forming operation is performed at the time of update, which is larger than the threshold value. It is characterized by that.
According to a thirteenth aspect of the present invention, in the image forming apparatus according to any one of the eighth to twelfth aspects, the updated density target value is higher than the density target value used immediately before the update, and the difference between the two is the difference. If the image forming operation exceeds the predetermined threshold value and the image forming operation is being performed at the time of update, the replenishment control unit is configured to temporarily interrupt the image forming operation and replenish toner to the developing unit. It is characterized by comprising.
According to a fourteenth aspect of the present invention, in the image forming apparatus of the thirteenth aspect, after the toner is supplied to the developing unit, the developer in the developing unit is stirred for a predetermined time, and then the image forming operation is resumed. It is characterized by doing so.
According to a fifteenth aspect of the present invention, in the image forming apparatus according to any one of the first to thirteenth aspects, a non-contact type IC chip capable of wireless communication is used as the information storage unit.

  In these inventions, the information storage means of the toner container is information on the toner density suitable for the physical properties of the toner contained in the toner container, or information useful for obtaining the toner density. Appropriate density information is stored. When the toner container is replaced with respect to the main body of the image forming apparatus, appropriate density information suitable for the physical properties of the toner stored in the new toner container after replacement is provided to the replenishment control unit. . In this way, the replenishment control means sets the density target value to a value suitable for the physical property of the toner after the replacement based on the appropriate density information suitable for the physical property of the toner after the replacement. As a result, even if the physical properties of the toner replenished to the developing means change due to the replacement of the toner container, the toner density is maintained in the vicinity of the appropriate toner density to obtain the target image density or the background is stained. Can be suppressed.

1 is a schematic configuration diagram showing a copier according to an embodiment. FIG. 2 is a partially enlarged configuration diagram illustrating an enlarged part of an internal configuration of a printer unit in the copier. FIG. 2 is an enlarged configuration diagram illustrating a process unit for Y in the printer unit. FIG. 2 is a perspective view showing an appearance of a copying machine of a copying machine. FIG. 3 is an enlarged perspective view showing a toner container for K. FIG. 2 is a partial perspective view showing a toner replenishing device and its peripheral configuration in the copier. FIG. 2 is a block diagram showing a part of an electric circuit in the copier. 6 is a graph showing an example of a relationship between an output voltage Vt [V] from a toner concentration sensor including a magnetic permeability sensor and a toner concentration in the developer. 7 is a graph showing the relationship between the toner charge amount [μC / g] in the developer stirred in the developing device, the temperature, and the toner concentration. 7 is a graph showing the relationship between the toner charge amount [μC / g] in the developer stirred in the developing device, the humidity, and the toner concentration. 5 is a flowchart illustrating a processing flow of image forming processing performed by a control unit. FIG. 3 is a schematic diagram illustrating an image for toner consumption transferred onto an intermediate transfer belt. 6 is a graph showing the relationship between the toner charge amount [μC / g] and the stirring time when the toner left for a long time is replenished in the developing device and then the toner is stirred in the developing device.

Hereinafter, as an image forming apparatus to which the present invention is applied, an embodiment of a copying machine that forms an image by an electrophotographic method will be described.
First, a basic configuration of the copying machine according to the present embodiment 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, a blank paper supply device 100, and a document conveyance reading unit 150. The document conveyance reading unit 150 includes a scanner 160 as a document reading device fixed on the printer unit 1 and an ADF 170 as a document conveyance device supported by the scanner 160.

  The blank paper supply apparatus 100 includes two paper feed cassettes 102 and 103, two pairs of separation roller pairs 104 and 105, a paper feed path 106, a plurality of transport roller pairs 107, and the like arranged in multiple stages in the paper bank 101. is doing. Each of the two paper feed cassettes 102 and 103 is housed in a paper bundle in which a plurality of recording papers (not shown) are stacked. Based on the control signal from the printer unit 1, the sending rollers 102 a and 103 a are driven to rotate, and the uppermost recording paper in the paper bundle is sent out toward the paper feed path 106. The fed recording paper is separated into one sheet by the pair of separation rollers 104 and 105 and then enters the paper feed path 106. Then, the sheet is fed to the first receiving branch path 30 of the printer unit 1 through the conveyance nips of the plurality of conveyance roller pairs 107 provided in the sheet feeding path 106.

  The printer unit 1 includes four process units 2Y, 2M, 2C, and 2K for forming yellow (Y), magenta (M), cyan (C), and black (K) toner images. Also, the first receiving branch path 30, the receiving conveyance roller pair 31, the manual feed tray 32, the manual separation roller pair 33, the second receiving branch path 34, the manual conveyance roller pair 35, the pre-transfer conveyance path 36, the registration roller pair 37, the conveyance A belt unit 39, a fixing unit 43, a switchback device 46, a discharge roller pair 47, a discharge tray 48, a switching claw 49, an optical writing unit 50, a transfer unit 60, and the like are also provided. The process units 2Y, 2M, 2C, and 2K have drum-shaped photoreceptors 3Y, 3M, 3C, and 3K that are latent image carriers.

  A pre-transfer conveyance path 36 for conveying a recording sheet immediately before a secondary transfer nip, which will be described later, is branched into a first reception branch path 30 and a second reception branch path 34 on the upstream side in the paper conveyance direction. The recording paper fed from the paper feed path 106 of the blank paper supply device 100 is received by the first receiving branch path 30 and then passed through the transport nip of the receiving transport roller pair 31 disposed in the first receiving branch path 30. Then, it is sent to the pre-transfer conveyance path 36.

  A manual feed tray 32 is disposed on the side surface of the housing of the printer unit 1 so as to be openable and closable with respect to the housing. The uppermost recording paper in the manually fed paper bundle is sent out toward the second receiving / branching path 34 by the feed roller 32 a of the manual feed tray 32. After being separated into one sheet by the manual feed separation roller pair 33 and sent to the second receiving branch path 34, it passes through the transport nip of the manual feed roller pair 35 disposed in the second receiving branch path 34. Then, it is sent to the pre-transfer conveyance path 36.

  The optical writing unit 50 includes a laser diode, a polygon mirror, various lenses (not shown), etc., and is based on image information read by a scanner 160 described later or image information sent from an external personal computer. Drive the laser diode. Then, the photoconductors 3Y, M, C, and K of the process units 2Y, M, C, and K are optically scanned. Specifically, the photoconductors 3Y, 3M, 3C, and 3K of the process units 2Y, 2M, 2C, and 2K are rotated in the counterclockwise direction in the drawing by driving means (not shown). The optical writing unit 50 performs an optical scanning process by irradiating the driven photosensitive members 3Y, 3M, 3C, and 3K while deflecting laser light in the direction of the rotation axis. Thereby, electrostatic latent images based on Y, M, C, and K image information are formed on the photoreceptors 3Y, 3M, 3C, and 3K.

  FIG. 2 is a partially enlarged configuration diagram illustrating a part of the internal configuration of the printer unit 1 in an enlarged manner. The process units 3K, Y, M, and C for the respective colors support the photosensitive member as a latent image carrier and various devices arranged around it on a common support as a unit. It is detachable from the printer unit main body. The configuration is the same except that the colors of the toners used are different. Taking the process unit 2Y for Y as an example, this has a developing device 4Y for developing an electrostatic latent image formed on the surface of the photoreceptor 3Y into a Y toner image in addition to the photoreceptor 3Y. Further, it also includes a drum cleaning device 18Y that cleans transfer residual toner adhering to the surface of the photoreceptor 3Y after passing through a Y primary transfer nip described later. This copying machine has a so-called tandem configuration in which four process units 2Y, 2M, 2C, and 2K are arranged along an endless movement direction with respect to an intermediate transfer belt 61 described later.

  FIG. 3 is an enlarged configuration diagram showing the Y process unit 2Y. As shown in the figure, the process unit 2Y includes a developing device 4Y, a drum cleaning device 18Y, a charge eliminating lamp 17Y, a charging roller 16Y, and the like around the photoreceptor 3Y.

  As the photoreceptor 3 </ b> Y, a drum-like member is used in which a photosensitive layer is formed by applying a photosensitive organic photosensitive material to a base tube made of aluminum or the like. However, an endless belt may be used.

  The developing device 4Y develops a latent image using a two-component developer (hereinafter simply referred to as developer) containing a magnetic carrier (not shown) and non-magnetic Y toner. And it has the stirring part 5Y which conveys the developer accommodated in the inside while stirring, and the developing part 9Y which develops the electrostatic latent image on the photoreceptor 3Y. The developing device 4Y may be of a type that performs development with a one-component developer that does not include a magnetic carrier, instead of the two-component developer.

  The agitating unit 5Y is provided at a position lower than the developing unit 9Y. The first conveying screw 6Y and the second conveying screw 7Y are arranged in parallel to each other, a partition plate provided between these screws, and the bottom surface of the casing. And a toner concentration sensor 8Y including a magnetic permeability sensor.

  The developing unit 9Y includes a developing roll 10Y that faces the photoreceptor 3Y through the opening of the casing, a doctor blade 13Y that makes its tip close to the developing roll 10Y, and the like. The developing roll 10Y includes a cylindrical developing sleeve 11Y made of a nonmagnetic material, and a magnet roller 12Y provided inside the developing roll 11Y so as not to rotate. The magnet roller 12Y has a plurality of magnetic poles arranged in the circumferential direction. Each of these magnetic poles applies a magnetic force to the developer on the sleeve at a predetermined position in the rotational direction. As a result, the developer sent from the stirring unit 5Y is attracted and carried on the surface of the developing sleeve 11Y, and a magnetic brush along the magnetic field lines is formed on the sleeve surface.

  The magnetic brush is transported to a developing region facing the photoreceptor 3Y after being regulated to an appropriate layer thickness when passing through a position facing the doctor blade 13Y as the developing sleeve 11Y rotates. Then, Y toner is transferred onto the electrostatic latent image by the potential difference between the developing bias applied to the developing sleeve 11Y and the electrostatic latent image on the photoreceptor 3Y, thereby contributing to development. Further, as the developing sleeve 11Y rotates, the developing sleeve 9Y returns to the developing portion 9Y again, and after the release from the sleeve surface due to the influence of the repulsive magnetic field formed between the magnetic poles of the magnet roller 12Y, the developing sleeve 11Y returns to the stirring portion 5Y. An appropriate amount of toner is supplied to the developer in the stirring unit 5Y based on the detection result of the toner density sensor 8Y.

  As the drum cleaning device 18Y, a system that presses the cleaning blade 20Y made of polyurethane rubber against the photoreceptor 3Y is used, but another system may be used. For the purpose of improving the cleaning property, this copying machine employs a system having a fur brush 19Y whose outer peripheral surface is in contact with the photoreceptor 3Y so as to be rotatable in the direction of the arrow in the figure. The fur brush 19Y also serves to apply the lubricant to the surface of the photoreceptor 3Y while scraping the lubricant from a solid lubricant (not shown) into a fine powder.

  The toner attached to the fur brush 19Y is transferred to the electric field roller 21Y to which a bias is applied while rotating in contact with the fur brush 19Y in the counter direction. And after scraping off from the electric field roller 21Y by the scraper 22Y, it falls on the collection | recovery screw 23Y.

  The collection screw 23Y conveys the collected toner toward the end of the drum cleaning device 18Y in the direction perpendicular to the drawing surface, and delivers it to an external recycling conveyance device. A recycle conveyance device (not shown) sends the delivered toner to the developing device 4Y for recycling.

  The neutralization lamp 17Y neutralizes the photoreceptor 3Y by light irradiation. The surface of the photoreceptor 3Y that has been neutralized is uniformly charged by the charging roller 16Y, and then subjected to optical scanning by the optical writing unit described above. The charging roller 16Y is rotationally driven while receiving a charging bias from a power source (not shown). Instead of the charging method using the charging roller 16Y, a scorotron charger method in which charging processing is performed in a non-contact manner on the photoreceptor 3Y may be employed.

  In FIG. 2 described above, Y, M, C, and K toner images are formed on the surfaces of the photoreceptors 3Y, M, C, and K of the four process units 2Y, 2M, 2C, and 2K by the processes described above. Is formed.

  A transfer unit 60 is disposed below the four process units 2Y, 2M, 2C, and 2K. The transfer unit 60 rotates in the clockwise direction in the drawing by rotating one of the rollers while contacting an intermediate transfer belt, which is an image carrier stretched by a plurality of rollers, with the photoreceptors 3Y, 3M, 3C, and 3K. Move endlessly in the direction. As a result, primary transfer nips for Y, M, C, and K in which the photoreceptors 3Y, 3M, 3C, and 3K contact the intermediate transfer belt 61 are formed.

  In the vicinity of the primary transfer nips for Y, M, C, and K, the intermediate transfer belt 61 is moved to the photosensitive members 3YY, M, C, and K by primary transfer rollers 62Y, M, C, and K disposed inside the belt loop. Pressing toward K. A primary transfer bias is applied to the primary transfer rollers 62Y, 62M, 62C, 62K by a power source (not shown). As a result, a primary transfer electric field for electrostatically moving the toner images on the photoreceptors 3Y, 3M, 3C, and 3K toward the intermediate transfer belt 61 is formed in the primary transfer nips for Y, M, C, and K. Has been.

  In the drawing, a toner image is formed on each of the primary transfer nips on the front surface of the intermediate transfer belt 61 that sequentially passes through the primary transfer nips for Y, M, C, and K with endless movement in the clockwise direction. Are sequentially superimposed and primarily transferred. By this primary transfer of superposition, a four-color superposed toner image (hereinafter referred to as a four-color toner image) is formed on the front surface of the intermediate transfer belt 61.

  A secondary transfer roller 72 is disposed below the intermediate transfer belt 61 in the drawing. The secondary transfer roller 72 contacts the secondary transfer backup roller 68 on the intermediate transfer belt 61 from the belt front surface. A secondary transfer nip is formed. As a result, a secondary transfer nip where the front surface of the intermediate transfer belt 61 and the secondary transfer roller 72 abut is formed.

  A secondary transfer bias is applied to the secondary transfer roller 72 by a power source (not shown). On the other hand, the secondary transfer backup roller 68 in the belt loop is grounded. Thereby, a secondary transfer electric field is formed in the secondary transfer nip.

  On the right side of the secondary transfer nip in the drawing, the above-described registration roller pair (not shown) is disposed, and the recording paper sandwiched between the rollers can be synchronized with the four-color toner image on the intermediate transfer belt 61. Send to the secondary transfer nip. In the secondary transfer nip, the four-color toner image on the intermediate transfer belt 61 is secondarily transferred onto the recording paper under the influence of the secondary transfer electric field and the nip pressure, and becomes a full color image combined with the white color of the recording paper.

  The transfer residual toner that has not been transferred to the recording paper at the secondary transfer nip adheres to the front surface of the intermediate transfer belt 61 that has passed through the secondary transfer nip. The transfer residual toner is cleaned by a belt cleaning application unit 75 that contacts the intermediate transfer belt 61.

  In FIG. 1 described above, the recording paper that has passed through the secondary transfer nip is separated from the intermediate transfer belt 61 and transferred to the transport belt unit 39. The transport belt unit 39 moves the endless transport belt 40 endlessly in the counterclockwise direction in the figure by the rotational drive of the drive roller 41 while being stretched by the drive roller 41 and the driven roller 42. The recording paper delivered from the secondary transfer nip is conveyed along with the endless movement of the belt while being held on the belt upper tension surface, and delivered to the fixing unit 43.

  In the fixing unit 43, a fixing belt stretched by a driving roller and a heating roller containing a heat generation source is moved endlessly in the clockwise direction in the drawing as the driving roller is driven to rotate. The pressure roller 45 disposed below the fixing belt is brought into contact with the lower tension surface of the fixing belt to form a fixing nip. The recording paper received by the fixing unit 43 is pressed or heated in the fixing nip, whereby the full-color image on the surface is fixed. Then, it is sent out from the fixing unit 43 toward the switching claw 49.

  The switching claw 49 is swung by a solenoid (not shown), and the recording paper conveyance path is switched between the paper discharge path and the reversing path with the swing. When the paper discharge path is selected by the switching claw 49, the recording paper fed out from the fixing unit 43 passes through the paper discharge path and the paper discharge roller pair 47 and is then discharged to the outside of the apparatus and discharged to the paper discharge tray. 48 is stacked.

  A switchback device 46 is disposed below the fixing unit 43 and the conveyor belt unit 39. When the switchback path is selected by the switching claw 49, the recording paper fed out from the fixing unit 43 is turned upside down via the reversing path and then sent to the switchback device 46. Then, the image enters the secondary transfer transfer nip again, and the secondary transfer processing and fixing processing of the image are performed on the other surface.

  The scanner 160 fixed on the printer unit 1 has a fixed reading unit 161 and a moving reading unit 162 as reading means for reading an image of a document (not shown). A fixed reading unit 161 having a light source, a reflection mirror, an image reading sensor such as a CCD, and the like is disposed immediately below a first contact glass (not shown) fixed to the upper wall of the casing of the scanner 160 so as to contact the document. . Then, when the document conveyed by the ADF 170 passes over the first contact glass, the light emitted from the light source is sequentially reflected by the document surface and is received by the image reading sensor via the plurality of reflection mirrors. Thus, the original is scanned without moving the optical system including the light source and the reflecting mirror.

  On the other hand, the moving reading unit 162 is disposed directly below a second contact glass (not shown) fixed to the upper wall of the casing of the scanner 160 so as to come into contact with the document, and an optical system including a light source, a reflection mirror, and the like. It can be moved in the left-right direction in the figure. Then, in the process of moving the optical system from the left side to the right side in the figure, the light emitted from the light source is reflected by a document (not shown) placed on the second contact glass and then passed through a plurality of reflecting mirrors. The image is received by an image reading sensor fixed to the scanner body. Accordingly, the original is scanned while moving the optical system.

  FIG. 4 is a perspective view showing an appearance of the copying machine according to the embodiment. As shown in the figure, four container storage holders 94Y, 94M, 94K, which can be opened and closed by turning around a rotation shaft (not shown) are provided on the front surface of the copier. Each of them accommodates and supports a toner container (for example, 90Y shown) corresponding to each color. For example, when the Y toner container 90Y is set in the container storage holder 94Y, the operator removes the lock (not shown) and rotates the container storage holder 94Y to the front side as shown in the figure to remove the container storage holder 94Y. Expose inside. Then, the toner container 90Y is set inside the container storage holder 94Y.

  FIG. 5 is an enlarged perspective view showing the K toner container 90K. The toner container 90K for K has a bag portion 91K having a storage space for storing Y toner (not shown) and a mouth portion 92K connected to the bag portion 91K. The bag portion 91K is designed to be reduced in volume by being deformed as the K toner contained therein is consumed. A taper is formed in the lower portion of the bag portion 91K, and the mouth portion 92K is connected to the end of the taper. As shown in the figure, the toner container 90K is set in the container storage holder (94K) with the mouth 92K facing downward. Then, the K toner in the bag portion 91K enters the mouth portion 92K by its own weight. The mouth portion 92K is made of a resin material having relatively high rigidity, and has a nozzle insertion hole 93K, an engagement groove 94K, a non-contact IC chip 95K, and the like. The nozzle insertion hole 93K is for inserting a nozzle of a K toner replenishing device described later. A cylindrical plug member (not shown) is slidably engaged with the nozzle insertion hole 93K. In this state, the K toner that has flowed into the opening 92K is blocked by the plug member. There is no leakage from the hole 93K. The two engaging grooves 94K provided in the mouth portion 92K are engaged with the two engaging rails of the K toner replenishing device. The non-contact type IC chip 95K is information storage means capable of transmitting individual identification information stored in a nonvolatile memory in the circuit by radio waves, such as a well-known RFID (Radio Frequency IDentification). .

  FIG. 6 is a partial perspective view showing the toner replenishing device and its peripheral configuration in the copying machine according to the embodiment. In the figure, among the four toner supply devices for Y, M, C, and K provided in the copier according to the embodiment, only the toner supply device for K 80K and the toner supply device for C are shown. Yes. In addition, in the figure, for convenience, the container storage holders 94Y, 94M, and 94C are shown for the three colors Y, M, and C, but K is set inside the container storage holder instead of the container storage holder. A toner container 90K is shown. The toner supply device 80K for K includes a nozzle 81K, two engagement rails 82K, a communication board (not shown), a conveyance tube 84K, a driving gear 85K, a clutch 86K, a suction pump 87K, a relay hopper 88K, a toner discharge port 89K, and the like. Have.

  A supply motor 95 rotates between the four toner supply devices for Y, M, C, and K and the four container storage holders (94Y, M, C, and K) for Y, M, C, and K. A driving shaft 96 to be driven is disposed. This driving shaft 96 is arranged in the direction in which the four container storage holders (94Y, M, C, K) are arranged and the direction in which the four developing devices (4Y, M, C, K) for Y, M, C, K are arranged. Extends along. Then, Y, M, C, and K driving gears (for example, 85K and 85C in the figure) respectively provided in the Y, M, C, and K toner supply devices are held. When the driving shaft 96 is rotated by driving the replenishing motor 95, the driving gears for Y, M, C, and K fixed to the driving shaft 96 are rotated.

  When the K toner container 90K is set in a K container holder (not shown), as shown in the figure, the two engagement rails 82K in the K toner replenishing device 80K are Engages with two engaging grooves (94K in FIG. 5) provided in the mouth portion 92K. Thereby, the mouth portion 92K is positioned. At the same time, the tip of the nozzle 81K in the K toner replenishing device 80K is inserted into the nozzle insertion hole of the mouth 92K of the toner container 90K. The plug member that has been engaged with the nozzle insertion hole is pushed out of the nozzle insertion hole. A toner receiving port (not shown) provided at the tip of the nozzle 81K communicates with the opening 92K, so that the K toner in the opening 92K can flow into the nozzle 81K.

  In the K toner replenishing device 80K, the suction pump 87K is connected to the rear end of the nozzle 81K via a possible conveyance tube 84K. The suction pump 87K exhibits suction force by driving, and discharges it into the relay hopper 88K while sucking K toner in the opening 92K of the toner container 90K into the transport tube 81K.

  The clutch gear of the clutch 86K is engaged with the driving gear 85K that is rotationally driven together with the driving shaft 96. The clutch 86K holds the clutch gear and the output gear on the same rotation axis. Then, by turning on and off the drive, the rotational driving force received from the clutch gear can be connected to the output gear, or can be stopped. The output gear of the clutch gear meshes with the pump gear of the suction pump 87K, and when the output gear rotates, the suction pump 87K is driven and K toner is fed into the relay hopper 88K.

  The toner replenishing devices for Y, M, C, and K (for example, 80K in the figure) each have a conveying screw member in a relay hopper (for example, 88K in the figure), and each conveying screw member has The rotational driving force from the replenishing motor 95 is transmitted to drive the rotation. When the transport screw member rotates, the toner in the relay hopper is discharged from the toner discharge port (for example, 89K in the figure) of the relay hopper and replenished into the developing device (for example, 4K in the figure). Although the K toner replenishing device 80K has been described, the toner replenishing devices for Y, M, and C have the same configuration.

  FIG. 7 is a block diagram showing a part of an electric circuit in the copying machine according to the embodiment. In the figure, the control unit 99 includes a CPU (Central Processing Unit) 99a, a RAM (Random Access Memory) 99b, a ROM (Read Only Memory) 99c, a flash memory 99d, and the like, which are stored in the ROM. The driving of various devices such as the process unit of each color and the optical writing unit 7 is controlled based on the control program. Various devices are connected to the control unit 99, but only a part of the devices is shown in the figure. The toner density sensors 8Y, 8M, 8C, and 8K connected to the control unit 99 detect the toner density of the Y, M, C, and K developers in the Y, M, C, and K developing devices. (See FIG. 2). Further, the clutches 86Y, 86M, 86C, 86K connected to the control unit 99 connect the rotational driving force of the replenishment motor 95 to the suction pumps for Y, M, C, K, or stop the connection. It is. The control unit 99 is for Y, M, C, K by arbitrarily turning on / off the clutch 86Y, M, C, K for Y, M, C, K with the replenishment motor 95 driven. Only any of the suction pumps can be driven to replenish toner only for any color.

  A temperature sensor 96 and a humidity sensor 97 are also connected to the control unit 99. The control unit 99 can grasp the temperature in the copying machine based on the output signal from the temperature sensor 96. Further, the humidity in the copying machine can be grasped based on the output signal from the humidity sensor 97.

  The Y, M, C, and K toner replenishing devices 80Y, 80M, 80C, and 80K have communication boards 83Y, 83M, 83C, and 83K, as shown. The communication boards 83Y, 83M, 83C, and 83K are fixed to the rails of the toner supply devices 80Y, 80M, 80C, and 80K (for example, 82K in FIG. 6). In the opening 92K of the toner container 90K shown in FIG. 5, the non-contact type IC chip 95K is fixed at a position where one of the bottom surfaces of the two engaging grooves 94K is formed. On the other hand, the communication board 83K shown in FIG. 7 is fixed to one of the two engaging rails 82K in the toner container 80K shown in FIG. 6, and the engaging groove 94K and the engaging rail are fixed. When engaged with 82K, the non-contact type IC chip 95K forming the groove bottom surface of the engagement groove 94K and the communication board 83K fixed to the engagement rail 82K face each other, and wireless communication between them is performed. Is possible. Information such as an ID number stored in the non-contact type IC chip 95K is read into the control unit 99 via the communication board 83K.

  FIG. 8 is a graph showing an example of the relationship between the output voltage Vt [V] from the toner concentration sensor composed of a magnetic permeability sensor and the toner concentration in the developer. As illustrated, the higher the toner concentration in the developer, the lower the output voltage Vt from the toner concentration sensor. This is because the higher the toner concentration, the more toner exists between the individual magnetic carrier particles contained in the developer, and the permeability of the developer decreases.

  In FIG. 7 described above, the control unit 99 stores a target voltage value Y− that is an output target value from the Y, M, C, and K toner density sensors 8Y, M, C, and K in the flash memory 99. Vtref, M-Vtref, C-Vtref, and K-Vtref are stored. These function as toner density target values for the Y, M, C, and K developers, respectively. For example, if the developer 99 is a K developer, the output voltage Vt from the toner density sensor 8K is larger than the target voltage value K-Vtref, and the difference between the two exceeds a predetermined threshold value, the K The clutch 83K of the toner replenishing device 80K is turned on for a predetermined time. As a result, K toner is replenished for a predetermined time, and the K toner density, which is lower than the density target value, is brought close to the density target value. The toner supply control for K has been described, but the same toner supply control is performed for Y, M, and C.

  FIG. 9 is a graph showing the relationship between the charge amount [μC / g] of toner in the developer stirred in the developing device, the temperature, and the toner concentration. FIG. 10 is a graph showing the relationship between the charge amount [μC / g] of toner in the developer stirred in the developing device, the humidity, and the toner concentration. As shown in these graphs, the charge amount of the toner varies depending on the temperature and humidity. When the toner charge amount is different, the toner density per unit area with respect to the electrostatic latent image is different, so that the development density is different. Further, as shown in the two graphs, the charge amount of the toner varies depending on the toner density. As the toner density increases, the charge amount decreases as shown in the figure. This is because the frictional force between the magnetic carrier and the toner decreases as the toner concentration increases. When the toner density is simply kept constant, if the charge amount of the toner changes due to a change in temperature and humidity, the development density becomes insufficient, or scumming occurs. Specifically, when the charge amount of the toner becomes excessive, the development density becomes insufficient. Further, when the toner charge amount is insufficient, background smearing occurs. When the development density is insufficient, it is possible to solve the shortage of development density by reducing the toner charge amount by increasing the toner density. In the case where scumming occurs, the scumming can be eliminated by increasing the charge amount of the toner by decreasing the toner density. In other words, the appropriate toner concentration that does not cause insufficient development density or background contamination varies depending on temperature and humidity. Therefore, conventionally, by correcting the target voltage value Vtref as the density target value according to the detection result of temperature and humidity, the toner density of the developer is maintained at an appropriate toner density regardless of the temperature and humidity. An image forming apparatus is known.

  However, even if the toner has the same specifications, if the production lot is different, an error occurs in the physical properties. Therefore, the characteristics shown in FIGS. 9 and 10 also have an error depending on the production lot. For this reason, even if the target voltage value Vtref is corrected according to temperature and humidity, the toner density target value may deviate from the appropriate toner density, which may cause insufficient development density and background contamination.

Next, a characteristic configuration of the copier according to the embodiment will be described.
In FIG. 5 shown above, information on the ID number which is the solid identification number of the toner container 90K, information on the density target table, information on the density / voltage conversion formula, etc. are recorded in the non-contact type IC chip 95K. ing. In the density target table, when the K toner stored in the bag portion 91K is a highly charged toner, for example, a density target table as shown in Table 1 below is recorded. In the case of low-charge toner, for example, a density target table as shown in Table 2 below is recorded.

  These density target tables function as appropriate density information that is information on the toner density suitable for the physical properties of the toner contained in the toner container 90K. It is constructed based on the result of actual investigation of the relationship among temperature, humidity, and appropriate toner concentration for each production lot. For example, when the density target table of Table 1 is recorded, the appropriate toner density of the K toner contained in the toner container 90K is 7 under the environment of temperature 20 [° C.] and humidity 50 [%]. 0.0 [%].

  The density / voltage conversion formula is a formula for converting the appropriate toner density into the output voltage from the corresponding toner density sensor. Since the correlation as shown in FIG. 8 is established between the toner density and the output voltage from the toner density sensor, the toner density and the output voltage correspond to the appropriate toner density by the density / voltage conversion formula which is an expression representing the correlation. The output voltage value can be converted. Such density / voltage conversion type information is recorded in the non-contact type IC chip 95K.

  Although the non-contact type IC chip 95K in the toner container 90K for K has been described, similar information is also recorded in the non-contact type IC chips of other colors (Y, M, C).

  FIG. 11 is a flowchart showing a processing flow of the image forming process performed by the control unit 99. When a print command signal is sent from an external personal computer or a scanner (Y in Step 1; hereinafter, Step is referred to as S), the control unit 99 is based on signals from the temperature sensor 96 and the humidity sensor 97. The temperature and humidity inside the machine is grasped (S2). Then, an appropriate toner density corresponding to the temperature and humidity is specified from a density target table stored in a non-contact IC chip (for example, 95K) (S3). Next, the density / voltage conversion formula information described above is read from the non-contact type IC chip, and the appropriate toner density is converted into the output voltage value from the toner density sensor. Then, the conversion result is determined as the target voltage value (Vtref) from the toner density sensor (S4). Then, it is determined whether or not the toner density needs to be adjusted for the developer in the developing device (S5). Specifically, first, a value obtained by subtracting the appropriate toner density specified in S3 from the toner density obtained based on the output voltage Vt from the toner density sensor (hereinafter referred to as “appropriate density difference”) is calculated. The condition that the “appropriate density difference” is larger than a lower limit value with a minus sign (for example, −0.5%) and smaller than a first upper limit value with a plus sign (for example, + 1.0%). It is determined whether it is equipped. Having this condition means that the toner density of the developer is within a predetermined range centered on the density target value. Therefore, in this case, the control unit 99 determines that the density adjustment process is not necessary (N in S5), and advances the control flow to S7 described later. On the other hand, if the above-described conditions are not satisfied, it is determined that the density adjustment process is necessary (Y in S5), the density adjustment process is performed (S6), and S7 described later is performed.

  In the density adjustment process, the control unit 99 first determines whether or not the “appropriate density difference” is equal to or less than the lower limit value (for example, whether it is −0.5% or less). If it is equal to or lower than the lower limit value, toner supply is performed until the output voltage Vt from the toner density sensor is lowered to the target voltage value (Vtref), that is, until the toner density is raised to the density target value. . On the other hand, if it is not less than the lower limit value, the “appropriate density difference” is greater than or equal to the first upper limit value (for example, + 1.0% or more), so that the toner in the developer is forcibly consumed. The forced consumption is performed by forming a predetermined forced consumption image on the surface of the photosensitive member, transferring the image onto the intermediate transfer belt 61, and then cleaning the belt with a belt cleaning device. By this forced consumption, the output voltage Vt from the toner density sensor is raised to the target voltage value. That is, the toner density is lowered to the density target value. In addition, about the process of S2-S6, it implements individually about each color of Y, M, C, and K, respectively.

  In step S7, it is determined whether or not image forming condition adjustment is necessary. Specifically, for each of the colors Y, M, C, and K, it is determined whether or not the difference between the target voltage value determined in S4 and the target voltage value so far exceeds a predetermined threshold value. If the predetermined threshold value is exceeded, the difference between the new appropriate toner concentration and the appropriate toner concentration that has been used so far is too large and may cause malfunctions. Readjust the image conditions. That is, it is determined that the image forming condition adjustment is necessary.

The image forming condition adjustment process (S8) is performed as follows. That is, a gradation pattern image for image density detection for Y, M, C, and K is formed on the intermediate transfer belt 61. The gradation pattern images for Y, M, C, and K are composed of a plurality of Y, M, C, and K reference toner images each having a predetermined pixel pattern. A plurality of Y, M, C, and K reference toner images are formed so as to have different toner adhesion amounts (image densities). For example, taking a K gradation pattern image as an example, this is a plurality of K reference toner images K reference toner images SK ₁ , SK ₂ , SK _3. It is composed of These K reference toner images are formed so as to be arranged at predetermined intervals in the traveling direction of the intermediate transfer belt 61. Then, the toner adhesion amount per unit area with respect to these K reference toner images is detected by a reflection type photo sensor (not shown) facing the intermediate transfer belt 61 at a predetermined distance. The detection result is sent to the control unit 99. Similarly, the amount of toner attached to each Y, M, C reference toner image in the Y, M, C gradation pattern image formed on the intermediate transfer belt 61 is detected. Based on the output value from the reflection type photosensor stored in the RAM 99b and the data table stored in the ROM 99c, the control unit 99 converts each output value into the toner adhesion amount per unit area, and the toner. It is stored in the RAM 99b as adhesion amount data. Then, a relational expression between the latent image potential and the toner adhesion amount is analyzed based on the sensor output value and the toner adhesion amount data stored in the RAM 99b, and based on the analysis result, an image forming condition (for example, development) is analyzed. Adjust bias and laser writing intensity).

  After finishing the image forming condition adjustment process or determining that the image forming condition adjustment process is not necessary, a print job process is performed (S9), and an image instructed to be printed is output onto a recording sheet.

  In the above configuration, the output target value (Vtref) as the density target value is obtained based on the density target table as the appropriate density information stored in the non-contact type IC chip of the toner container (90Y, M, C, K). By determining, regardless of the toner production lot, the density target value is set to the same value as the appropriate toner density suitable for the physical properties of the toner contained in the toner container. As a result, the toner density of the developer in the developing device (4Y, M, C, K) is maintained in the vicinity of the appropriate toner density regardless of the toner production lot, and regardless of the toner production lot. It is possible to obtain a target image density and to suppress the occurrence of background stains.

  Each of the non-contact type IC chips (for example, 95K) mounted on the toner containers 90Y, 90M, 90C, 90K stores information on ID numbers unique to the containers. When the toner container is replaced in each of the colors Y, M, C, and K, the ID number value read from the non-contact type IC chip is different. The control unit 99 detects that the toner container has been replaced based on the change in the ID number for each color. In other words, in this copying machine, a combination of a non-contact IC chip for each color (for example, 95K), a communication board for each color (for example, 83K), and the control unit 99 detects the replacement of the toner container. It functions as a means.

Next, a description will be given of the copying machine of each example in which a more characteristic configuration is added to the copying machine according to the embodiment. Unless otherwise specified, the configuration of the copying machine according to each example is the same as that of the embodiment.
[First embodiment]
Immediately after the toner container is replaced, the replenished toner is renewed. However, until a large amount of toner is replenished, most of the toner in the developer in the developing device is old toner (old toner). Supplied from the container). Therefore, the value of the proper toner density is closer to the proper toner density corresponding to the old toner than the proper toner density corresponding to the new toner. Nevertheless, immediately after the replacement of the toner container, if the target density value is updated to the same value as the appropriate toner density of the replaced toner, the development density deficiency and background contamination will be encouraged. There is a risk that.

  Therefore, when the control unit 99 in the copier according to the first embodiment detects the replacement of the toner container for each of the colors Y, M, C, and K, after that, until a predetermined information exchange timing comes. Is used as the density target table (appropriate density information) stored in the non-contact type IC chip of the toner container before replacement. On the other hand, after the information exchange timing arrives, the density target table stored in the non-contact type IC chip of the toner container after the exchange is used.

  The information exchange timing described above is determined for each of the colors Y, M, C, and K based on the accumulated toner replenishment amount from the toner container after the replacement to the developing device, and the control unit 99 serving as a replenishment control unit. Is configured. Specifically, the control unit 99 previously stores a toner supply amount calculation formula for calculating the toner supply amount for each color based on the driving time of the suction pump (for example, 87K) of the toner supply device (for example, 80K) in the ROM 99c. Remembered in. Then, based on the toe replenishment amount calculated based on this toner replenishment amount calculation formula, the cumulative toner replenishment amount immediately after the toner container replacement is calculated. Next, the ratio of the cumulative toner replenishment amount with respect to the total toner amount accommodated in the developing device is calculated, and the time when the calculated result reaches a predetermined threshold is defined as the information exchange timing. In the first embodiment, a specific numerical value in the range of 50 to 300 [%] is adopted as the aforementioned threshold value. In other words, when the ratio of the cumulative toner replenishment amount to the total toner amount in the developing device reaches a specific value within the range of 50 to 300 [%], the density target table (appropriate density information) to be used is replaced. The toner stored in the non-contact IC chip of the toner container is switched to the one stored in the non-contact IC chip of the replaced toner container. In order to enable such switching, both density target tables before and after replacement are copied from the non-contact IC chip into the flash memory.

  In such a configuration, when the cumulative toner replenishment amount reaches a certain value and the ratio of the new toner replenished from the toner container after replacement out of the total toner amount in the developing device increases to some extent, Switch the target table to one corresponding to the toner after replacement. As a result, immediately after the toner container is replaced and most of the toner in the developing device is the old toner, a new density toner table corresponding to the old toner is used so that the new toner can be used immediately after the replacement. Insufficient development density and background contamination due to the use of matching density target tables can be avoided.

  Similarly to the embodiment, the control unit 99 is based on the temperature detection result by the temperature sensor 96, the humidity detection result by the humidity sensor 97, and the concentration target table (either new or old) stored in the flash memory 99d. Thus, the target voltage value (Vtref) as the density target value is periodically updated. The regular update timing is when a print command from the user is received, as in the embodiment. In addition, in the copier according to the first embodiment, the target voltage value is updated based on the temperature and humidity every time a predetermined number of printing operations are performed during the continuous printing operation. Hereinafter, these update timings are referred to as regular update timings. In such a configuration, the toner concentration of the developer can be maintained in the vicinity of the proper toner concentration in the actual temperature and humidity environment regardless of the change in temperature and humidity.

  When the target voltage value (Vtref) updated at the regular update timing is higher than the target voltage value used until immediately before the update and the difference between the two exceeds the first upper limit value, the updated concentration target value Is lower than the density target value before update, and the difference between the two exceeds 0.5 [%], which is the first threshold value. Hereinafter, such a case is referred to as “a case where the target density decrease due to the update exceeds 0.5 [%]”. Generally, the toner density immediately before the update is adjusted near the density target value immediately before the update. For this reason, when “the target density decrease due to renewal exceeds 0.5%”, the developer toner density is higher than the appropriate toner density and the difference between the two is 0.5%. That is, it is in a state where soiling is likely to occur. Therefore, the control unit 99 serving as the forced consumption control means is “when the target density decrease by updating exceeds 0.5%” for any one of the four colors Y, M, C, and K. If the print job is not in progress, a forced consumption process is performed to forcibly consume the toner by forming a toner consumption image on the photoconductor for that color before starting the print job. To do. For example, in the case of two colors Y and C, a toner consumption image for Y is formed on the Y photoconductor (3Y) prior to the print job, and the C color is used. A toner consumption image for C is formed on the photoreceptor (3C). Then, they are primarily transferred onto the intermediate transfer belt 61 and then cleaned by a belt cleaning device 75. The area of the toner consumption image is determined according to the target density difference before and after the update. The larger the target density difference, the larger the area of the toner consumption image. By forming such a toner consumption image and forcibly consuming the toner, the toner density of the developer is lowered to near the density target value.

  If the target voltage value after updating at the regular update timing is higher than the target voltage value used until immediately before the update, and the difference between the two exceeds the second upper limit value, the updated density target value is not updated. This is lower than the density target value, and the difference between the two exceeds 1.0 [%], which is the second threshold value. Hereinafter, such a case is referred to as “when the target density decrease due to renewal exceeds 1.0 [%]”. In this case, the toner density of the developer is higher than the appropriate toner density, and the difference between the two exceeds 1.0 [%], and it is in a state in which scumming is very likely to occur. Therefore, the control unit 99 is the case where any one of the four colors Y, M, C, and K is “when the target density decrease due to the update exceeds 1.0 [%]” and is continuous. When the print job is in progress, the continuous print job is temporarily interrupted, and a forced consumption process is executed for forming the toner consumption image on the photoreceptor and forcibly consuming the toner for that color. As a result, the toner density of the developer is reduced to near the density target value, and then the continuous print job is resumed.

In addition, the control unit 99 has a target density decrease due to the update between 0.5 [%] and 1.0 [%] for any one of the four colors Y, M, C, and K, If the continuous print job is in progress, a process for forming an image for toner consumption is performed for the color in the inter-paper corresponding area of the photoconductor while continuing the continuous print job. The inter-paper corresponding area of the photoreceptor is an area between consecutive pages during continuous printing of an image over a plurality of pages. For example, it is an area between the 103rd page and the 104th page which are mutually continuous. As shown in FIG. 12, the toner consumption image Pa formed in the inter-paper corresponding area is primarily transferred between two adjacent page corresponding areas A ₁ on the surface of the intermediate transfer belt 61. Even during the continuous printing operation, secondary transfer is not performed on the recording paper. Then, the belt is cleaned from the belt by the belt cleaning device (75). In this way, the toner density of the developer is lowered to near the density target value while continuing the continuous print job.

  When the target voltage value updated at the regular update timing is lower than the target voltage value used until immediately before the update and the difference between the two exceeds the first upper limit value, the updated concentration target value is It is higher than the density target value before the update, and the difference between both exceeds 0.5 [%]. Hereinafter, such a case is referred to as “when the target density increase due to the update exceeds 0.5 [%]”. In this case, the toner density of the developer is lower than the appropriate toner density, and the difference between the two exceeds 0.5 [%], so that it is easy to cause insufficient development density. Therefore, the control unit 99 determines that any one of the four colors Y, M, C, and K is “when the target density increase due to the update exceeds 0.5 [%]” and is printed. If the job is not in progress, the toner is replenished to the developing device until the output value from the toner density sensor is lowered to the vicinity of the target voltage value for that color prior to starting the print job. Thus, when the toner density is increased to near the density target value, the developing device is driven for a predetermined time or more to stir the developer in the device for a predetermined time or more, and then a print job is started.

  In addition, the control unit 99 determines that any one of the four colors Y, M, C, and K is “when the target density increase due to the update exceeds 0.5 [%]” and is continuous. If the print job is in progress, after the continuous print job is temporarily interrupted, toner is replenished to the developing device until the output value from the toner density sensor is lowered to the vicinity of the target voltage value for that color. Thus, when the toner density is increased to near the density target value, the developing device is driven for a predetermined time or more to stir the developer in the device for a predetermined time or more, and then the continuous print job is resumed.

  The reason why the developer is stirred for a predetermined time or more before starting a print job or resuming a continuous print job is as follows. That is, FIG. 13 is a graph showing the relationship between the toner charge amount [μC / g] and the stirring time when the toner left for a long time is replenished in the developing device and then the toner is stirred in the developing device. . As illustrated, the toner charge amount before the start of stirring is a very low value. Then, the increase starts immediately after the start of stirring, and the toner charge amount increases as the stirring time increases. However, if the stirring time increases to a certain extent, the toner charge amount reaches saturation, and after that, it does not increase. Thus, by increasing the toner charge amount to approximately saturation and then starting the print job or restarting the continuous print job, it is possible to avoid the occurrence of background contamination due to the insufficient toner charge amount.

[Second Embodiment]
When the control unit 99 in the copying machine according to the second embodiment detects replacement of the toner container for each of the colors Y, M, C, and K, replacement is performed until a predetermined calculation method change timing comes. A pre-replacement table (pre-replacement information) that is a density target table (appropriate density information) stored in the non-contact IC chip of the previous toner container, and a non-contact IC chip of the toner container after the replacement The density target value (target voltage value) calculated based on the post-replacement table (post-replacement information) that is the density target table and the accumulated toner supply amount from the toner container to the developing device after the replacement is used. On the other hand, after the calculation method change timing arrives, the concentration target value (target voltage value) calculated based only on the post-exchange table among the pre-exchange table and the post-exchange table is used.

  In order to realize such processing, the control unit 99 calculates the accumulated toner replenishment amount after the toner container replacement for each color in the same manner as the copying machine according to the first embodiment. Then, based on the accumulated toner supply amount, an old toner ratio, which is a ratio of the old toner supplied from the toner container before replacement, out of the total toner amount in the developing device is calculated. Specifically, in the developing device, the developer in the device is uniformly stirred and mixed to such an extent that there is no difference between the old toner ratio in the developing device and the old toner ratio in the consumed toner. The balance of the old toner in the minute period (Δp) is expressed by the equation “ΔC (p) × W = C (p) × w”. In the formula, C (p) represents the old toner ratio. Further, w represents the cumulative toner supply amount. W represents the total toner amount [g] in the developing device. The left side of the equation represents the amount of decrease in old toner in the developing device. The right side represents the amount of old toner in the consumed toner. When this equation is transformed and integrated, an equation “ln (C (p)) = − (w / W) + α” is obtained (α is an integration constant). Then, by transforming this expression, an expression “C (p) = exp (−w / W + α)” is obtained. Under the condition that the number of printed sheets p = 0 [sheets], the new toner is not yet supplied into the developing device and C (p) = 1. Therefore, when this is the initial condition, α = 0, so “C ( p) = exp (−w / W) ”. The control unit 99 calculates the old toner ratio C (p) using this equation.

  Next, the control unit 99 calculates the density target value using the formula “density target value = first target value × old toner ratio + second target value × (1−old toner ratio)”, and then the calculation result A target voltage value corresponding to is calculated. Then, the target voltage value up to that time is updated to the same value as the calculation result. In the above-described formula, the first target value is a concentration target value specified based on the pre-replacement table and the temperature / humidity detection result. The second target value is a concentration target value specified based on the post-replacement table and the temperature / humidity detection result. By using such an equation, as the old toner ratio becomes smaller, the ratio of reflecting the density target value based on the pre-replacement table corresponding to the old toner is reduced with respect to the actual density target value. Then, the ratio of reflecting the density target value based on the post-replacement table corresponding to the new toner is increased. When the old toner ratio decreases to a predetermined value, the ratio for reflecting the density target value based on the pre-replacement table corresponding to the old toner is set to 0 [%] with respect to the actual density target value. The ratio for reflecting the density target value based on the post-replacement table corresponding to the new toner is set to 100 [%]. In the following, an example will be described in which when the old toner ratio is reduced to 5 [%], the ratio for reflecting the density target value based on the post-replacement table corresponding to the new toner is set to 100 [%].

  In the copying machine according to the second embodiment, the time when the old toner ratio reaches 5% is set as the calculation method change timing. When the calculation method timing comes, the target voltage value (Vtref) is periodically updated based on the temperature / humidity detection result using only the post-replacement table. The regular update timing for updating the target voltage value based on the temperature / humidity detection result is the same as in the first embodiment. In addition, the toner density is adjusted in the same manner as in the first embodiment when there is a difference between the target voltage value before update and the target voltage value after update at the time of regular update.

  In the copying machine according to the second embodiment having the above-described configuration, the density target value is set to the appropriate toner density by accurately reflecting the ratio of the old and new toner to the density target value as compared with the copying machine according to the first embodiment. Can be approached.

  As described above, in the copying machine according to the first embodiment, for each color, as a replacement detection unit that detects replacement of the toner container, a combination of a non-contact IC chip, a communication board, and the control unit 99 is used. Provided. Then, when the replacement of the toner container is detected, the replacement stored in the non-contact type IC chip of the toner container before the replacement as the proper density information until the predetermined information exchange timing comes after that. Use the front table. Further, after the information exchange timing has arrived, control as a replenishment control means is performed so as to perform processing using the post-replacement table stored in the non-contact type IC chip of the toner container after the replacement as appropriate density information. Part 99 is configured. In such a configuration, after replacement of the toner container, until the new toner ratio becomes high to some extent, the target voltage value (Vtref), which is the density target value, is determined in accordance with the physical properties of the old toner, whereby the toner in the developer is determined. Although most of the toner is old, it is possible to avoid determining the target voltage value in accordance with the physical properties of the new toner.

  Further, in the copying machine according to the second embodiment, for each color, as a replacement detection means for detecting the replacement of the toner container, a combination of a non-contact IC chip, a communication board, and a control unit 99 is used. Provided. Then, when the replacement of the toner container is detected, the non-contact type of the toner container before the replacement is used as the target voltage value (Vtref) as the density target value until a predetermined calculation method change timing comes thereafter. The pre-replacement table stored in the IC chip, the post-replacement table stored in the non-contact IC chip of the replaced toner container, and the cumulative toner supply amount from the replaced toner container to the developing device. A value calculated based on the above is used. On the other hand, after the calculation method change timing has arrived, a process using a value calculated based only on the post-replacement table of the pre-replacement table and the post-replacement table as the target voltage value that is the concentration target value is performed. Thus, the control part 99 which is a supply control means is comprised. In such a configuration, after replacement of the toner container, until the new toner ratio increases to some extent, the density target value is determined according to both the physical properties of the old toner and the physical properties of the new toner. Even though most of the toner is old toner, it is possible to avoid determining the density target value according to only the physical properties of the new toner.

  Further, in the copying machine according to the second embodiment, before the calculation method change timing arrives, based on the accumulated toner replenishment amount, the total toner amount in the developing device is replenished from the toner container before replacement. The control unit 99 is configured to calculate the old toner ratio, which is the ratio of the old toner that has been used, and to calculate the density target value based on the calculation result, the pre-replacement table, and the post-replacement table. . In such a configuration, the density target value is set to an appropriate toner density as compared with the first embodiment by reflecting the density target value based on the physical properties of the old toner in the actual density target value at a ratio according to the old toner ratio. You can get closer.

  Further, in the copying machine according to the first embodiment, the control unit 99 is configured to perform the process of determining the information exchange timing based on the accumulated toner supply amount from the toner container after the replacement to the developing device. is doing. In such a configuration, when the new toner ratio increases to some extent, the density target table used for specifying the density target value can be switched from the pre-replacement table to the post-replacement table.

  Further, in the copying machine according to the second embodiment, the control unit 99 is configured to execute the process of determining the calculation method change timing based on the accumulated toner supply amount from the toner container after replacement to the developing device. It is composed. In such a configuration, when the accumulated toner replenishment amount increases to some extent, the density target value can be calculated by a calculation method that does not take into account the physical properties of the old toner.

  In the copier according to the second embodiment, the old toner ratio, which is the ratio of the old toner replenished from the toner container before replacement, out of the total toner amount in the developing device based on the accumulated toner replenishment amount. And the control unit 99 is configured to execute a process of determining the calculation method change timing based on the calculation result. In such a configuration, the density target value can be calculated by a calculation method that does not take into account the physical properties of the old toner when the old toner ratio decreases to a certain level (when it reaches 5% in the embodiment).

  Further, the copying machine according to the first embodiment is provided with a temperature sensor and a humidity sensor as environment detecting means. Then, as a density target table serving as appropriate density information, information useful for obtaining appropriate toner densities for various temperature and humidity conditions is stored in the non-contact type IC chip. Further, the control unit 99 is configured to periodically perform a process of updating the target voltage value, which is a density target value, based on the temperature / humidity detection result and the density target table. In such a configuration, the toner density can be maintained in the vicinity of the appropriate toner density regardless of the temperature and humidity.

  In the copying machine according to the second embodiment, a temperature sensor and a humidity sensor as environment detecting means are provided. As the density target table, what is useful for obtaining the appropriate toner density for various temperature and humidity conditions is stored in the non-contact IC chip. Furthermore, before the calculation method change timing arrives, the density target value is periodically updated to a value calculated based on the temperature / humidity detection result, the pre-replacement table, the post-replacement table, and the cumulative toner supply amount. Then, after the calculation method change timing has arrived, the control unit 99 is set so that the concentration target value is periodically updated to a value calculated based on the temperature / humidity detection result and the post-replacement table. It is composed. In such a configuration, the toner density can be maintained in the vicinity of the appropriate toner density regardless of the temperature and humidity.

  In the copiers according to the first and second embodiments, the updated density target value is lower than the density target value used until immediately before the update, and the difference between the two is a predetermined first threshold value. The control unit 99 serving as a forced consumption control unit is configured to execute a forced consumption process for forming a toner consumption image on the photosensitive member and forcibly consuming the toner. In such a configuration, when the target density reduction due to the update exceeds a predetermined first upper limit value, the toner density of the developer can be quickly lowered to the vicinity of the appropriate toner density.

  In the copiers according to the first and second embodiments, the updated density target value is lower than the density target value used until immediately before the update, and the difference between the two is a predetermined first threshold value. And the second threshold value (first threshold value <second threshold value), and if a continuous print job is being performed at the time of update, a toner consumption image is formed in the inter-paper corresponding area on the photoconductor. The control part 99 is comprised so that the process to perform may be implemented. In such a configuration, when the target density decrease due to the update is between the predetermined first upper limit value and the second upper limit value, the toner density of the developer is quickly adjusted to the appropriate toner density without interrupting the continuous printing operation. It can be reduced to near.

  In the copiers according to the first and second embodiments, the updated density target value is lower than the density target value used immediately before the update, and the difference between the two is less than the second threshold value. The control unit 99 is configured to execute processing for temporarily suspending the continuous print job and forming an image for toner consumption when the print job is large and is being continuously updated. In such a configuration, if there is a very high possibility that scumming will occur due to the toner concentration being too high, the continuous print job is temporarily suspended, and the toner density is lowered to the vicinity of the appropriate toner concentration, thereby causing scumming. After the occurrence is suppressed, the continuous print job can be resumed.

  In the copying machine according to the first embodiment or the second embodiment, the updated density target value is higher than the density target value used until immediately before the update, and the difference between the two exceeds a predetermined threshold value. In addition, when a continuous print job is in progress at the time of update, the control unit 99 is configured to perform a process of temporarily interrupting the continuous print job and supplying toner to the developing device. In such a configuration, when there is a very high possibility that the toner density is too low and the development density is insufficient, the continuous print job is temporarily suspended, and the toner density is increased to the vicinity of the appropriate toner density. The continuous print job can be resumed after the occurrence of the shortage is suppressed.

  In the copiers according to the first and second embodiments, after the toner is supplied to the developing device during interruption of the continuous print job, the developer in the developing device is stirred for a predetermined time and then continuously. The print job is resumed. In such a configuration, by increasing the charge amount of the replenished toner to near saturation and then restarting the continuous print job, it is possible to suppress the occurrence of scumming due to insufficient charge amount.

  In the copiers according to the first and second embodiments, the non-contact type IC chip capable of wireless communication is used as the information storage means, so that the electrical contacts are connected as the toner container is attached / detached. The density target table can be read by the control unit 99 without adopting a complicated configuration to be separated.

3Y, M, C, K: photoconductor (latent image carrier)
4Y, M, C, K: Developing device (developing means)
8Y, M, C, K: Toner density sensor (toner density detection means)
80K: Toner supply device (toner supply means)
83K: Communication board (part of replacement detection means)
90Y, M, C, K: Toner container 95K: Non-contact IC chip (part of replacement detection means, information storage means)
99: Control unit (part of replacement detection means, supply control means, forced consumption control means

JP 2008-122537 A

Claims (15)

A latent image carrier for carrying a latent image;
Developing means for developing the latent image on the latent image carrier using a developer containing toner and carrier;
Toner density detecting means for detecting the toner density of the developer in the developing means;
A toner container configured to store toner for replenishing the developing unit and to be detachable from the image forming apparatus main body;
Toner replenishing means for replenishing the developing means with toner in the toner container;
In an image forming apparatus, comprising: a replenishment control unit that controls driving of the toner replenishing unit based on a result of comparison between a detection result by a toner concentration detecting unit and a density target value.
Information storage means for storing appropriate density information which is information of toner density suitable for the physical properties of the toner contained in the toner container or information useful for obtaining the toner density In the container,
An image forming apparatus, wherein the replenishment control unit is configured to perform a process of determining the density target value based on the appropriate density information. The image forming apparatus according to claim 1.
While providing replacement detection means for detecting the replacement of the toner container,
When replacement of the toner container is detected by the replacement detection unit, the proper density information is stored in the information storage unit of the toner container before replacement until a predetermined information exchange timing is reached. After the information exchange timing has arrived, the replenishment is performed such that the processing using the information stored in the information storage means of the toner container after the replacement is performed as the appropriate density information. An image forming apparatus comprising a control means. The image forming apparatus according to claim 1.
While providing replacement detection means for detecting the replacement of the toner container,
When replacement of the toner container is detected by the replacement detection means, thereafter, the density target value is stored in the information storage means of the toner container before replacement until a predetermined calculation method change timing comes. The pre-replacement information that is the proper density information that has been performed, the post-replacement information that is the proper density information stored in the information storage means of the toner container after replacement, and the toner container after replacement While using the value calculated based on the cumulative toner replenishment amount to the developing means, after the calculation method change timing has arrived, as the density target value, among the pre-replacement information and the post-replacement information, An image forming apparatus according to claim 1, wherein the replenishment control unit is configured to perform a process using a value calculated based only on the post-exchange information. The image forming apparatus according to claim 3.
Before the calculation method change timing arrives, based on the accumulated toner replenishment amount, old toner that is the ratio of the old toner replenished from the toner container before replacement out of the total toner amount in the developing means An image forming apparatus comprising: the supply control unit configured to calculate a ratio and to calculate the density target value based on the calculation result, the pre-exchange information, and the post-exchange information. . The image forming apparatus according to claim 2.
An image forming apparatus comprising: the supply control unit configured to perform a process of determining the information exchange timing based on a cumulative toner supply amount from the toner container after replacement to the developing unit. The image forming apparatus according to claim 3 or 4,
An image forming apparatus comprising: the supply control unit configured to perform a process of determining the calculation method change timing based on a cumulative toner supply amount from the toner container after replacement to the developing unit. . The image forming apparatus according to claim 6.
Based on the accumulated toner replenishment amount, out of the total toner amount in the developing unit, an old toner ratio that is a ratio of the old toner replenished from the toner container before replacement is calculated, and based on the calculation result, An image forming apparatus according to claim 1, wherein the replenishment control means is configured to perform processing for determining the calculation method change timing. The image forming apparatus according to claim 2 or 5,
An environment detection means is provided to detect the environment.
As the appropriate density information, information useful for obtaining appropriate toner concentrations for various environmental conditions is stored in the information storage means,
An image characterized in that the replenishment control means is configured to periodically execute the process of updating the density target value based on the detection result by the environment detection means and the appropriate density information. Forming equipment. The image forming apparatus according to claim 3, 4, 6, or 7.
An environment detection means is provided to detect the environment.
As the appropriate density information, information useful for obtaining appropriate toner concentrations for various environmental conditions is stored in the information storage means,
In addition, before the calculation method change timing arrives, the density target value is calculated based on the detection result by the environment detection means, the pre-replacement information, the post-replacement information, and the cumulative toner supply amount. On the other hand, after the calculation method change timing arrives, the concentration target value is periodically updated to a value calculated based on the detection result by the environment detection means and the post-exchange information. An image forming apparatus, wherein the replenishment control unit is configured to perform the processing. The image forming apparatus according to claim 8 or 9,
When the updated density target value is lower than the density target value used immediately before the update and the difference between the two exceeds a predetermined threshold value, a toner consumption image is formed on the latent image carrier. An image forming apparatus comprising forced consumption control means for executing forced consumption processing for forcibly consuming toner. The image forming apparatus according to claim 10.
The updated density target value is lower than the density target value used until immediately before the update, and the difference between the two is a value between a predetermined first threshold and a second threshold (first threshold < (Second threshold value), and when the image forming operation is performed at the time of updating, the forced consumption control is performed so as to perform the process of forming the toner consumption image in the inter-paper corresponding region of the latent image carrier. An image forming apparatus comprising a means. The image forming apparatus according to claim 11.
The updated density target value is lower than the density target value used until immediately before the update, the difference between the two is larger than the second threshold value, and the image forming operation is performed at the time of updating. The image forming apparatus is characterized in that the forced consumption control means is configured to perform a process of temporarily interrupting an image forming operation to form the toner consumption image. The image forming apparatus according to any one of claims 8 to 12,
When the updated density target value is higher than the density target value used until immediately before the update, the difference between the two exceeds a predetermined threshold, and the image forming operation is performed at the time of update, An image forming apparatus comprising: the replenishment control unit configured to temporarily interrupt an image forming operation and replenish toner to the developing unit. The image forming apparatus according to claim 13.
An image forming apparatus, wherein after the toner is supplied to the developing unit, the developer in the developing unit is stirred for a predetermined time and then the image forming operation is resumed. The image forming apparatus according to claim 1,
An image forming apparatus using a non-contact IC chip capable of wireless communication as the information storage means.

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