Image forming apparatus

Abstract

To prevent image quality degradation without requiring extra time when replenishing the developer. [Solution] In the image forming system 1, if the toner level in the ID becomes low or empty while the image forming apparatus 2 is performing the printing process, the user is instructed to open the toner cover 21 and replace the toner cartridge 51 while the printing process continues. Furthermore, once the toner cartridge 51 has been successfully replaced, the image forming apparatus 2 changes the development voltage applied to the development roller 64 to a lower value. This allows the image forming system 1 to replenish toner in the image forming apparatus 2 without interrupting the printing process, and effectively suppresses changes in image quality due to differences in the electrostatic properties of the newly supplied toner.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus, and is suitable for application to, for example, an electrophotographic printer.

Background Art

[0002] In recent years, as an image forming apparatus, for example, a toner image (also called a developer image) using toner (also called a developer) is formed by an image forming unit, and the toner image is transferred onto a sheet conveyed by a conveying unit, and heat or pressure is applied to the sheet by a fixing unit to fix it, thereby printing an image.

[0003] Further, as an image forming apparatus, there is one in which a toner cartridge (also called a developer container) containing toner is configured to be detachable from the apparatus main body, and the toner is replenished by replacing the toner cartridge. Furthermore, as an image forming apparatus, when the toner cartridge is replaced, correction processing such as density correction and color shift correction is performed to prevent deterioration of image quality (see, for example, Patent Document 1). In density correction, for example, an adjustment toner image is transferred onto a belt or the like of a conveying unit to detect its density, and the density of the toner is corrected according to the detected density.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in an image forming apparatus having such a configuration, there is a problem that during the correction processing, printing processing on the sheet cannot be executed, so it takes time until the printing processing is completed.

[0006] This invention was made in consideration of the above points, and aims to propose an image forming apparatus that can suppress the deterioration of image quality without requiring extra time when replenishing the developer. [Means for solving the problem]

[0007] To solve these problems, the image forming apparatus of the present invention includes a developer container that is detachably attached to the main body of the apparatus and contains a developer, an image forming unit that moves the developer supplied from the developer container to an image carrier for development, a replacement detection unit that detects when the developer container is to be replaced, and a control unit that, when the replacement detection unit detects when the developer container is to be replaced, controls the image forming unit to improve the ease of movement of the developer compared to before the developer container was replaced.

[0008] The present invention controls the ease with which the developer can move in the image forming unit to be greater than before the developer container was replaced, when the developer container is replaced by the user and this is detected by the replacement detection unit. Therefore, even though the chargeability of the new developer supplied from the replaced developer container may be relatively low, the present invention increases the ease with which the developer can move, thereby enabling the formation of a high-quality developer image with an appropriate amount of developer without the need for correction processing. [Effects of the Invention]

[0009] According to the present invention, an image forming apparatus can be realized that can suppress the deterioration of image quality without requiring extra time when replenishing the developer. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing the configuration of the image forming system. [Figure 2] This is a schematic perspective view showing the external configuration of an image forming apparatus. [Figure 3] This is a schematic diagram showing the configuration of the image forming unit. [Figure 4] This is a schematic block diagram illustrating the circuit configuration of an image forming system. [Figure 5] This is a schematic flowchart illustrating the low state response processing procedure according to the first embodiment. [Figure 6] This is a schematic diagram showing the state of each part in the low state. [Figure 7] This is a schematic flowchart illustrating the empty state handling procedure according to the first embodiment. [Figure 8] This is a schematic diagram showing the state of each part in an empty state. [Figure 9] This flowchart shows the toner cartridge replacement processing procedure according to the second embodiment. [Modes for carrying out the invention]

[0011] The embodiments for carrying out the invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

[0012] [1. First Embodiment] [1-1. Configuration of the Image Forming System] [1-1-1. Configuration of the image forming apparatus, continuous paper feeding apparatus, and winding apparatus] As shown in Figure 1, the image forming system 1 according to the first embodiment is centered around an image forming apparatus 2, and the image forming apparatus 2 is combined with a continuous paper supply device 3 and a winding device 4.

[0013] The image forming apparatus 2 is an electrophotographic printer, and its various parts are centrally controlled by the control unit 5. This image forming apparatus 2 is connected to a higher-level device 100 (Figure 4), such as a computer, and when it receives print instructions or print data from this higher-level device 100, it performs a printing process to form an image on the surface of the paper P.

[0014] Incidentally, the image forming apparatus 2 does not have an image scanner function for reading a document, a communication function using a telephone line, etc., and is a single function SFP (Single Function Printer) having only a printer function. Further, the image forming apparatus 2 can be used as a single unit without using the continuous paper feeding device 3 and the winding device 4. However, in the present embodiment, the description will be made on the premise of a configuration in which the continuous paper feeding device 3 and the winding device 4 are combined with the image forming apparatus 2.

[0015] The continuous paper feeding device 3 holds, for example, a roll paper RP in which a long paper P (also called continuous paper) having a length of about 1000 [m] is wound in a cylindrical shape in advance, pulls out the paper P from the roll paper RP, cuts it to a predetermined length, and supplies it to the image forming apparatus 2. The winding device 4 receives the paper P on which an image is printed by the image forming apparatus 2 and winds it up in a cylindrical shape.

[0016] Incidentally, hereinafter, with the right end portion in FIG. 1 being defined as the front of the image forming system 1, the description will be made after defining the vertical direction, the horizontal direction, and the front-rear direction when viewed facing this front.

[0017] The continuous paper feeding device 3 is disposed on the front side of the image forming apparatus 2, and components such as a roll paper holder 11, a paper remaining amount sensor 12, a tension roller 13, a pair of feed rollers 14, a cutter 15, and a pair of conveyance rollers 16 are provided inside a housing 10 formed in a small rectangular parallelepiped shape as compared with the image forming apparatus 2.

[0018] The roll paper holder 11 rotatably holds the roll paper RP. Inside the housing 10, a conveyance path W1, which is a path along which the paper P pulled out from the roll paper RP is conveyed, is formed. This conveyance path W1 is formed so as to proceed obliquely downward from the upper rear portion on the outer periphery of the roll paper RP, proceed obliquely upward rearward after passing under the tension roller 13, and proceed rearward after passing between the pair of feed rollers 14.

[0019] The paper remaining amount sensor 12 detects the remaining amount of roll paper RP held in the roll paper holder 11 and notifies the control unit 5. The tension roller 13 applies a downward force to the paper P pulled from the roll paper RP, thereby giving the paper P a predetermined tension.

[0020] The feed roller pair 14 grips the paper P from above and below with a pair of rollers, and feeds the paper P backward by the rotation of the rollers. The cutter 15 cuts the paper P based on the control of the control unit 5. The transport roller pair 16 feeds the paper P backward and hands it over to the image forming apparatus 2.

[0021] The image forming apparatus 2 has a configuration in which various components are provided inside a rectangular parallelepiped housing 20 (hereinafter also referred to as the main body of the apparatus) which is larger than the continuous paper feeder 3. As shown in the schematic perspective view in Figure 2(A), a display and operation unit 6 is provided on the upper rear side of the left side of the housing 20, which displays various information and accepts operation input. This display and operation unit 6 has, for example, a touch panel which combines a display panel such as a liquid crystal panel with a touch sensor, or an LED (Light Emitting Diode), and displays various information based on the control of the control unit 5, as well as accepting operation input from the user.

[0022] On the left side of the housing 20, there is a toner cover 21 that covers the upper portion in front of the display operation unit 6, and an image drum (ID) cover 22 that covers the central portion in the vertical direction.

[0023] The toner cover 21 has a hinge 21H formed near its upper end, and can rotate around the housing 20 by a range of approximately 90 degrees using the hinge 21H as the pivot point. As shown in Figure 2(A), when the toner cover 21 is rotated by approximately 90 degrees from a closed state covering the left side of the housing 20, it becomes an open state as shown in Figure 2(B), opening the left side of the housing 20 and exposing the toner cartridge 51, etc., which will be described later, to the outside.

[0024] The ID cover 22 has a hinge 22H formed near its lower end, and when the toner cover 21 is in the open state, it can rotate around the hinge 22H as the pivot point within a range of approximately 90 degrees relative to the housing 20. As shown in Figures 2(A) and (B), when the ID cover 22 is rotated approximately 90 degrees from the closed state covering the left side of the housing 20, it becomes an open state, as shown in Figure 2(C), which opens the left side of the housing 20 and exposes the ID unit 53, etc., which will be described later, to the outside.

[0025] The housing 20 is also equipped with a toner cover detection sensor 23 for detecting whether or not the toner cover 21 is blocked, and an ID cover detection sensor 24 for detecting whether or not the ID cover 22 is blocked.

[0026] In the image forming apparatus 2 (Figure 1), a straight transport path W2 is formed below the center, generally oriented in the front-to-back direction. A tray 26 is provided at the very bottom of the housing 20. Paper P, consisting of pre-cut sheets (also called single sheets) of A3 or A4 size, is stored in this tray 26. A cut paper supply unit 27 is provided above and in front of the tray 26.

[0027] The cut paper supply unit 27 is configured such that paper feed rollers 28, various rollers (not shown), transport guides, etc., are appropriately arranged along an arc-shaped transport path W3. Based on the control of the control unit 5, the cut paper supply unit 27 rotates each roller appropriately to pick up the paper P contained in the tray 26 one sheet at a time, transports it along the transport path W3, and hands it over to the transport roller pair 29. Incidentally, in the image forming apparatus 2, the paper P supplied from the continuous paper supply unit 3 is also handed over to the transport roller pair 29.

[0028] The transport roller pair 29 is positioned on the transport path W2 and, similar to the feed roller pair 14, grips the paper P with the pair of rollers and transports the paper P backward along the transport path W2 by the rotation of the rollers.

[0029] An intermediate transfer section 30 is provided above the transport path W2 within the housing 20, and above it, five image forming sections 31 (31Y, 31C, 31M, 31K, and 31W) are arranged in a line from rear to front.

[0030] The intermediate transfer section 30 is composed of drive rollers 41 and 42, secondary transfer opposing rollers 43 and 44, an intermediate transfer belt 45 and a cleaning section 46, etc. Of these, the drive rollers 41 and 42 and the secondary transfer opposing rollers 43 and 44 are all formed in a cylindrical shape with their central axis aligned in the left-right direction and are rotatably supported.

[0031] The drive rollers 41 and 42 are positioned near the rear and front ends of the intermediate transfer section 30, respectively, and rotate in the direction of arrow R1 when driving force is supplied from the intermediate transfer belt motor, which will be described later. The secondary transfer opposing roller 43 is located approximately midway between the drive rollers 41 and 42 in the front-rear direction, and below the drive rollers 41 and 42 in the up-down direction, with its lower end in contact with the transport path W2. The secondary transfer roller 44 is located directly below the secondary transfer opposing roller 43, facing the secondary transfer opposing roller 43 across the transport path W2. A predetermined high voltage is also applied to the secondary transfer roller 44.

[0032] The intermediate transfer belt 45 is a flexible, endless belt that is stretched around the drive rollers 41 and 42 and the secondary transfer opposing roller 43. The upper portion of this intermediate transfer belt 45 (hereinafter referred to as the upper intermediate transfer belt 45U) is stretched in a straight line connecting the vicinity of the upper end of the drive roller 41 and the vicinity of the upper end of the drive roller 42.

[0033] Five image forming units 31 are positioned so as to be in contact with the upper part 45U of the intermediate transfer belt. Each image forming unit 31 forms a toner image and transfers the toner image to the upper part 45U of the intermediate transfer belt (details will be described later).

[0034] Furthermore, the lower end of the intermediate transfer belt 45 is held between the secondary transfer opposing roller 43 and the secondary transfer roller 44 on the transport path W2. Hereafter, the secondary transfer opposing roller 43 and the secondary transfer roller 44 will be collectively referred to as the secondary transfer section 48.

[0035] With this configuration, when the drive rollers 41 and 42 rotate in the direction of arrow R1 in the intermediate transfer unit 30, the intermediate transfer belt 45 moves in the direction of arrow E1. This causes the intermediate transfer unit 30 to bring the toner image transferred from the image forming unit 31 to the secondary transfer unit 48. At this time, if the paper P is being transported along the transport path W, the secondary transfer unit 48 can transfer the toner image from the intermediate transfer belt 45 to the paper P. Hereinafter, this transfer will also be referred to as secondary transfer.

[0036] The cleaning unit 46 has a plate-shaped cleaning blade 46A and a rectangular waste toner box 46B, and is positioned behind the drive roller 41 so that the cleaning blade 46A contacts the intermediate transfer belt 45. If toner remains in the secondary transfer unit 48 without being transferred from the intermediate transfer belt 45 to the paper P, the cleaning unit 46 scrapes off the toner with the cleaning blade 46A and stores it in the waste toner box 46B.

[0037] A fixing section 32 is provided on the rear side of the secondary transfer section 48. The fixing section 32 includes a heating roller 32A and a pressure roller 32B, etc. The heating roller 32A and the pressure roller 32B are each rotatably supported in a position that sandwiches the conveying path W2 from above and below. The heating roller 32A is heated to a predetermined temperature by a heater (not shown). The pressure roller 32B is biased against the heating roller 32A by a predetermined biasing member.

[0038] When printing is to be performed, the fixing unit 32 rotates the heating roller 32A and the pressure roller 32B in advance and heats the heating roller 32A. When the paper P is transported along the transport path W2, the fixing unit 32 grips the paper P with the heating roller 32A and the pressure roller 32B and applies heat and pressure to fix the toner to the paper P, and then feeds the paper P backward.

[0039] A discharge switch 33 is provided on the rear side of the fixing unit 32. The discharge switch 33 is a part that allows the user to manually switch the transport direction of the paper P to either the rearward direction or the rearward-upward direction. When the winding device 4 is used, the transport direction of the paper P is switched to the rearward direction, and when the winding device 4 is not used, the transport direction of the paper P is switched to the rearward-upward direction.

[0040] A transport path W4 is formed on the upper rear side of the discharge switch 33, and a discharge transport unit 34 is provided along this transport path W4. The discharge transport unit 34 has a transport guide and a pair of transport rollers (neither of which are shown) along the transport path W4, and a discharge roller 35, etc. A paper output tray 36 is formed on a part of the upper surface of the housing 20, which is in front of the discharge roller 35. When paper P is handed over from the discharge switch 33, the discharge transport unit 34 transports the paper P along the transport path W4, and then discharges the paper P from the discharge roller 35 and places it on the paper output tray 36.

[0041] Meanwhile, the paper P sent to the rear from the discharge switch 33 is handed over to the winding device 4. The winding device 4 is located at the rear of the image forming apparatus 2 and has a winding shaft 38 and a winding motor (described later) inside a casing 37 that is smaller than the image forming apparatus 2 and shaped like a rectangular parallelepiped. The winding shaft 38 is shaped like a cylinder along the left-right direction and is rotatably supported by the casing 37. When driving force is supplied from the winding motor 97 (Figure 4) to the winding shaft 38 based on the control of the control unit 5, the winding device 4 winds up the paper P.

[0042] In this way, the image forming apparatus 2 sequentially transports the paper P drawn from the roll paper RP along the transport path W, transfers the toner images formed by each image forming unit 31 to the paper P using the secondary transfer unit 48, and fixes them in the fixing unit 32, thereby forming an image on the paper P, i.e., printing.

[0043] [1-1-2. Configuration of the Image Forming Unit] Next, the image forming units 31 (31Y, 31C, 31M, 31K, and 31W) of the image forming apparatus 2 will be described. Each image forming unit 31 corresponds to one of the colors: yellow (Y), cyan (C), magenta (M), black (K), and white (W), but only the color differs; all are configured similarly.

[0044] Each image forming unit 31 includes a toner cartridge 51, a toner supply duct 52, an image drum (ID) unit 53, an exposure head 54, and a primary transfer roller 55, as shown in the schematic enlarged view in Figure 3. Of these, the toner cartridge 51 and the ID unit 53 are configured to be detachable from the housing 20.

[0045] In other words, as shown in Figure 2(B), the toner cartridge 51 can be attached and detached by the user when the toner cover 21 of the image forming apparatus 2 is open. Also, as shown in Figure 2(C), the ID unit 53 can be attached and detached by the user when the ID cover 22 of the image forming apparatus 2 is open.

[0046] Incidentally, the image forming unit 31 and each component that comprises it have sufficient length in the left-right direction, corresponding to the left-right length of the paper P. For this reason, many components have a relatively longer left-right length compared to their front-to-back and up-to-down lengths, and are formed in an elongated shape along the left-right direction.

[0047] The toner cartridge 51, which serves as a developer container, has a space inside for storing toner, and the toner is discharged to the toner supply duct 52 from an outlet formed on the lower side. The toner, as a developer, is a fine powder and has the property of being electrically charged.

[0048] Furthermore, a toner delivery body 57, which has a spiral-shaped component and is configured to be rotatable, is provided inside the toner cartridge 51. When driving force is supplied to this toner delivery body 57 from a toner supply motor 93 (Figure 4) located on the housing 20 side of the image forming apparatus 2, it rotates, thereby appropriately agitating the toner inside the toner cartridge 51 and sending it to the toner supply duct 52.

[0049] Furthermore, the toner cartridge 51 is equipped with a wireless tag 58. The wireless tag 58 is, for example, a film-like substrate on which electronic components such as an IC (Integrated Circuit) chip are mounted, and an antenna is formed by a circuit pattern. This IC chip stores an identification number uniquely assigned to each toner cartridge 51 and various other information. When this toner cartridge 51 is mounted in the housing 20, a toner cartridge tag reader 77 (Figure 4) provided in the housing 20 communicates wirelessly with the wireless tag 58, and the identification number and various other information are read out.

[0050] The toner supply duct 52 is a tubular section that connects the upper toner cartridge 51 and the lower ID unit 53, and is fixed to the housing 20. Inside this toner supply duct 52 is a toner supply unit 59, which has a configuration similar to that of the toner delivery unit 57. When driving force is supplied to this toner supply unit 59 from the duct stirring motor 94 (Figure 4), which will be described later, it rotates and delivers the toner in the toner supply duct 52 to the ID unit 53.

[0051] The ID unit 53, as an image forming unit, has a toner storage space 61 for storing toner inside the ID unit housing 60, which is a holding part that constitutes the outer shell, and an ID internal toner detection sensor 62 for detecting the remaining amount of toner in the toner storage space 61. A supply roller 63, a developing roller 64, a layer forming blade 65, a photoreceptor drum 66, a charging roller 67, and a cleaning member 68 are appropriately arranged below or behind the toner storage space 61.

[0052] The toner storage space 61, which serves as the developer storage section, forms a space large enough to accommodate a certain amount of toner, and stores the toner supplied from the toner supply duct 52 inside. The ID internal toner detection sensor 62, which serves as the remaining amount detection section, detects the remaining amount of toner in the toner storage space 61 and notifies the control unit 5. Specifically, the ID internal toner detection sensor 62 can detect three states of toner remaining in the toner storage space 61: "full state," where there is sufficient toner and a toner image can be formed, as well as "low state" and "empty state." The low state is a state where the remaining amount of toner is relatively small, but a toner image can still be formed. On the other hand, the empty state is a state where the remaining amount of toner is extremely small, making it difficult to continue forming a toner image.

[0053] The supply roller 63, developing roller 64, photoreceptor drum 66, charging roller 67, and primary transfer roller 55 are all cylindrical or cylindrical in shape with their central axis aligned in the left-right direction, and are rotatably supported. These rollers and drums are rotated by the driving force supplied from the ID motor 90, which will be described later.

[0054] The supply roller 63, acting as a toner supply unit, is positioned at the bottom of the toner storage space 61. The developer roller 64, acting as a developer carrier, is positioned diagonally above and behind the supply roller 63, in contact with both the supply roller 63 and the photoreceptor drum 66. Both the supply roller 63 and the developer roller 64 are formed in a cylindrical shape with their central axis aligned in the left-right direction, and are rotatably supported by the ID unit housing 60 around their respective central axes. A predetermined high voltage, which is the supply voltage and the development voltage, is applied to the supply roller 63 and the developer roller 64, respectively. The layer-forming blade 65 is formed in a thin plate shape, with one end fixed to the ID unit housing 60 and the other end in contact with the circumferential surface of the developer roller 64, and further applies an elastic force to the developer roller 64.

[0055] The photoreceptor drum 66, which serves as the image carrier, is formed in a cylindrical shape with its central axis aligned in the left-right direction, and is rotatably supported by the ID unit housing 60 around this central axis. The photoreceptor drum 66 is also made capable of being charged by sequentially forming thin film charge generation layers and charge transport layers on its circumferential surface. The charging roller 67, which serves as the charging body, is formed in a cylindrical shape with its central axis aligned in the left-right direction, is rotatably supported by the ID unit housing 60, and is positioned to abut the front upper side of the photoreceptor drum 66.

[0056] The exposure head 54, which serves as both an electrostatic latent image formation unit and an exposure unit, is formed in a long, slender rod shape aligned in the left-right direction and is located above the photoreceptor drum 66. This exposure head 54 has multiple LED (Light Emitting Diode) elements, which are light-emitting elements, arranged along the main scanning direction (i.e., the left-right direction), as well as a rod lens array and the like.

[0057] Based on the control of the exposure control unit 82 (Figure 4), which will be described later, the exposure head 54 causes each LED element to emit light appropriately with an amount of light corresponding to the magnitude of the supplied voltage and current, i.e., the amount of energy. As a result, the exposure head 54 irradiates while focusing the light downwards, forming an image near the upper end of the peripheral surface of the photoreceptor drum 66, thereby exposing the surface of the photoreceptor drum 66 and forming an electrostatic latent image.

[0058] The cleaning member 68 is provided on the front side of the photoreceptor drum 66 and is made of a flexible resin material in the shape of a thin plate. The upper end of the cleaning member 68 is fixed to the ID unit housing 60 and the area near the lower end is in contact with the peripheral surface of the photoreceptor drum 66.

[0059] The primary transfer roller 55 is formed in a cylindrical shape with its central axis aligned in the left-right direction, and is positioned below the intermediate transfer belt 45, facing the photoreceptor drum 66. This primary transfer roller 55 is biased upward, i.e., toward the photoreceptor drum 66, by a biasing member (not shown). As a result, the primary transfer roller 55 sandwiches the intermediate transfer belt 45 between itself and the photoreceptor drum 66. Hereinafter, the location where the intermediate transfer belt 45 is sandwiched (i.e., nipped) by the photoreceptor drum 66 and the primary transfer roller 55 will be referred to as the primary transfer area QC.

[0060] In this configuration, when each image forming unit 31 performs printing, it rotates the toner dispenser 57 in the toner cartridge 51 to send toner to the toner supply duct 52 based on the control of the control unit 5, and rotates the toner supply unit 59 in the toner supply duct 52 to supply the toner to the ID unit 53.

[0061] Furthermore, each image forming unit 31 rotates the developing roller 64, charging roller 67, and primary transfer roller 55 of the ID unit 53 in the direction of arrow R1, based on the control of the control unit 5, and rotates the photoreceptor drum 66 and supply roller 63 in the direction of arrow R2. At the same time, the image forming unit 31 supplies a predetermined high voltage to the supply roller 63, developing roller 64, layer forming blade 65, charging roller 67, and primary transfer roller 55, based on the control of the control unit 5.

[0062] The charging roller 67, while charged, contacts the photoreceptor drum 66, thereby uniformly charging the circumferential surface of the photoreceptor drum 66. The supply roller 63, through charging, causes toner in the toner storage space 61 to adhere to its circumferential surface, and through rotation, this toner adheres to the circumferential surface of the developing roller 64. After the developing roller 64 has excess toner removed from its circumferential surface by the layer-forming blade 65, forming a thin layer of toner, it brings this thin layer of toner into contact with the circumferential surface of the photoreceptor drum 66.

[0063] Meanwhile, the control unit 5 generates print data based on the print job acquired from the host device 100 (Figure 4), and supplies this print data to the exposure head 54 as dot data for each line. The exposure head 54 emits light according to the light emission pattern based on the supplied dot data, exposing the photoreceptor drum 66. As a result, an electrostatic latent image is formed on the peripheral surface of the photoreceptor drum 66 near its upper end.

[0064] Next, the photoreceptor drum 66 rotates in the direction of arrow R2, bringing the area where the electrostatic latent image was formed into contact with the developing roller 64. As a result, toner adheres to the peripheral surface of the photoreceptor drum 66 based on the electrostatic latent image, and a toner image based on the image data is developed. The developed toner image reaches the primary transfer area QC, which is the point where it is clamped with the primary transfer roller 55, as the photoreceptor drum 66 rotates.

[0065] At this time, the image forming unit 31 uses a high voltage applied to the primary transfer roller 55 to transfer the toner image from the peripheral surface of the photoreceptor drum 66 to the intermediate transfer belt 45 at the primary transfer area QC. Hereinafter, this transfer will also be referred to as primary transfer. Incidentally, if toner remains on the peripheral surface of the photoreceptor drum 66 after passing through the primary transfer area QC, the image forming unit 31 scrapes off the toner with the cleaning member 68.

[0066] In this way, the image forming unit 31 can form a toner image based on the print data and transfer the toner image to the intermediate transfer belt 45. The toner image transferred to the intermediate transfer belt 45 is then transferred to the paper P that has been transported along the transport path W in the secondary transfer unit 48, as described above.

[0067] [1-1-3. Circuit configuration of the image forming apparatus] Next, the circuit configuration of the image forming system 1 will be explained with reference to the block diagram in Figure 4. The image forming system 1 is configured such that each part is connected to the control unit 5 of the image forming apparatus 2.

[0068] The control unit 5 contains a CPU (Central Processing Unit) 71, ROM (Read Only Memory) 72, RAM (Random Access Memory) 73, and flash memory 74, among other things. The control unit 5 can perform various processes by having the CPU 71 read various programs and information from the ROM 72 or flash memory 74 as appropriate, and then loading and executing them in the RAM 73.

[0069] The interface unit 75 is a connection terminal such as a wired LAN that conforms to standards such as IEEE (Institute of Electrical and Electronics Engineers) 802.3 (IEEE802.3u / ab / an), and transmits and receives various information with the host device 100.

[0070] The sensor detection unit 76 includes, for example, a temperature sensor and a humidity sensor, and notifies the control unit 5 of the detected temperature, humidity, etc. The toner cartridge tag reader 77, which acts as a replacement detection unit, is positioned near the location where the toner cartridge 51 is installed in each image forming unit 31. When this toner cartridge tag reader 77 reads the identification number and various information from the wireless tag 58 (Figure 3) of the toner cartridge 51, it notifies the control unit 5 of the read identification number and information.

[0071] In response, the control unit 5 stores the identification number read this time in the flash memory 74, and by comparing the identification number that was previously read and stored in the flash memory 74 with the newly notified identification number, it can determine whether or not the toner cartridge 51 has been replaced.

[0072] The process control unit 78 controls the voltage applied to each roller constituting the image forming unit 31 (Figure 3). The developing voltage control unit 79 controls the voltage applied to the developing roller 64 (Figure 3) of the image forming unit 31. The layer formation / supply voltage control unit 80 controls the voltage applied to the supply roller 63 and layer formation blade 65 of the image forming unit 31. The charging voltage control unit 81 controls the voltage applied to the charging roller 67 of the image forming unit 31.

[0073] The exposure control unit 82 controls the exposure amount of the photoreceptor drum 66 by controlling the amount of energy, such as the magnitude of the voltage and current supplied to the exposure head 54 of the image forming unit 31. The primary transfer control unit 83 controls the voltage applied to the primary transfer roller 55 of the image forming unit 31. The secondary transfer control unit 84 controls the voltage applied to the secondary transfer roller 44 of the secondary transfer unit 48 (Figure 1).

[0074] The print dot count control unit 85 counts the number of dots that caused each exposure head 54 to emit light, based on the dot data supplied to each color exposure head 54, and records these counts in the count recording unit 86.

[0075] The motor control unit 88 controls the drive of each motor, including the belt motor 89, ID motor 90, fuser motor 91, transport motor 92, toner supply motor 93, duct stirring motor 94, feed motor 95, cutter motor 96, and winding motor 97.

[0076] Of these, the belt motor 89 drives the intermediate transfer belt 45 by supplying driving force to the drive rollers 41 and 42 of the intermediate transfer section 30 (Figure 1). The ID motor 90 rotates the photoreceptor drum 66 and developing roller 64, etc., provided in the image forming section 31 (Figure 3), by supplying driving force to them. The fixing motor 91 rotates the heating roller 32A and pressure roller 32B of the fixing section 32 (Figure 1), by supplying driving force to them, respectively.

[0077] The transport motor 92 rotates by supplying driving force to the transport roller pair 29 (Figure 1), etc. The toner supply motor 93 rotates by supplying driving force to the toner discharge body 57 of the toner cartridge 51 (Figure 3), and delivers toner from the toner cartridge 51 to the toner supply duct 52. The duct stirring motor 94 rotates by supplying driving force to the toner supply body 59 of the toner supply duct 52 (Figure 3), and supplies toner from the toner supply duct 52 to the ID unit 53.

[0078] The feed motor 95 rotates the feed roller pair 14 of the continuous paper supply device 3 (Figure 1) by supplying driving force, thereby transporting the paper P. The cutter motor 96 cuts the paper P by supplying driving force to the cutter 15 of the continuous paper supply device 3. The winding motor 97 rotates the winding shaft 38 of the winding device 4 by supplying driving force, thereby winding the paper P.

[0079] [1-2. Procedures related to toner cartridge replacement] Next, we will explain how to replace the toner cartridge 51 in the image forming apparatus 2 of the image forming system 1. The image forming apparatus 2 constantly monitors the remaining amount of toner in the toner storage space 61 (hereinafter referred to as the remaining toner amount in the ID) using ID toner detection sensors 62 provided in each of the image forming units 31 (Figure 3), including while the printing process is waiting or in progress.

[0080] When the image forming apparatus 2 detects that the toner level has become low or empty using the ID toner detection sensor 62, it prompts the user to replace the toner cartridge 51 and has the user replace the toner cartridge 51.

[0081] In particular, the image forming apparatus 2 is configured so that the toner cartridge 51 can be replaced while the ID cover 22 remains closed by opening the toner cover 21. In other words, the image forming apparatus 2 allows the toner cartridge 51 to be replaced even when printing is being performed and the ID unit 53 is operating.

[0082] Incidentally, in the image forming section 31 (Figure 3) of the image forming apparatus 2, when the amount of toner remaining in the toner storage space 61 is relatively small, the toner remaining in the toner storage space 61 is agitated for a relatively long period of time, resulting in a relatively high charge level. When a toner image is formed in the image forming section 31, such toner is more likely to move from the developing roller 64 to the photoreceptor drum 66. As a result, the toner image formed in this way tends to have a relatively large amount of toner attached and a high density.

[0083] On the other hand, when the toner cartridge 51 is replaced, a relatively large amount of new toner supplied via the toner supply duct 52 is contained in the toner storage space 61. Since this new toner has hardly been agitated, it is in a state of relatively low electrostatic charge. When a toner image is formed in the image forming unit 31, this toner is less likely to move from the developing roller 64 to the photoreceptor drum 66. As a result, the toner image formed in this way tends to have a relatively small amount of toner attached and a low density.

[0084] Therefore, when the toner cartridge 51 is replaced, the image forming apparatus 2 changes the development voltage applied to the development roller 64 to suppress a significant change in the image quality of the printed image. The image forming apparatus 2 also adjusts the development voltage to a value corresponding to the remaining amount of toner in the ID.

[0085] The following sections describe the detailed processing procedures for when the toner level in the ID becomes low and when it becomes empty.

[0086] [1-2-1. When the toner level in the ID becomes low] First, we will explain the printing process when the toner level in the ID becomes low. When the control unit 5 receives a print job from the host device 100 (Figure 4) and the printing process is started accordingly, it reads the low-level toner response program from the flash memory 74 and executes it, thereby starting the low-level toner response procedure RT1 shown in Figure 5.

[0087] The waveforms shown in Figure 6 represent the voltages of each part of the image forming apparatus 2, the detection status by each sensor, and the drive status of each motor, as timing charts. Specifically, Figure 6(A) shows the developing voltage applied to the developing roller 64 by the control of the developing voltage control unit 79. The vertical axis in Figure 6(A) represents negative voltage [V], and moving upwards means that the absolute value of the voltage is larger.

[0088] Figure 6(B) shows the remaining toner level in the ID as detected by the ID toner detection sensor 62, in three stages: "full," "low," or "empty." Figure 6(C) shows the state of the toner cover 21 as detected by the toner cover detection sensor 23, where "on" means it is blocked and "off" means it is not blocked.

[0089] Figure 6(D) shows the drive state of the toner supply motor 93 (Figure 4) and the operating state of the toner dispenser 57 within the toner cartridge 51 (Figure 3). Figure 6(E) shows the drive state of the ID motor 90 (Figure 4) and the operating state of the photoreceptor drum 66, developing roller 64, and other rollers within the ID unit 53.

[0090] In the image forming apparatus 2, when the low state response processing procedure RT1 (Figure 5) is started, the process moves to the first step SP1. At this time, each part of the image forming apparatus 2 is in the state shown at time t10 in Figure 6.

[0091] In step SP1, the control unit 5 determines whether the remaining toner level in the ID detected by the ID toner detection sensor 62 is low. If a positive result is obtained, this indicates that the toner will run out soon and printing will not be able to continue, so it is desirable for the user to replace the toner cartridge 51. At this point, the control unit 5 moves to the next step SP2.

[0092] In step SP2, the control unit 5 displays a message on the display operation unit 6 indicating that the toner level in the ID is low, and then proceeds to the next step SP3. This message notifies the user that the remaining amount of toner in the toner cartridge 51 is relatively low and urges them to replace it with a new toner cartridge 51 soon.

[0093] In step SP3, the control unit 5 stops the toner supply motor 93 (Figure 4), thereby stopping the toner dispenser 57 in the toner cartridge 51 (Figure 3), and proceeds to the next step SP4. However, at this time, the control unit 5 continues to operate the intermediate transfer unit 30 and the ID unit 53 by continuing to drive the belt motor 89 and the ID motor 90, etc., and continues the currently running printing process. As a result, each part of the image forming apparatus 2 is in the state shown at time t11 in Figure 6. Incidentally, if the toner supply motor 93 had already stopped, the control unit 5 continues to keep the toner supply motor 93 stopped.

[0094] In step SP4, the control unit 5 determines whether the toner cover 21 has been opened based on the detection signal obtained from the toner cover detection sensor 23. If a negative result is obtained, the control unit 5 repeats step SP4 and waits for the toner cover 21 to be opened. On the other hand, if a positive result is obtained in step SP4, this indicates that the user may intend to open the toner cover 21 and replace the toner cartridge 51. At this point, the control unit 5 moves to the next step SP5. At this time, each part of the image forming apparatus 2 is in the state shown at time t12 in Figure 6.

[0095] In step SP5, the control unit 5 stops the toner supply unit 59 in the toner supply duct 52 by stopping the duct stirring motor 94 (Figure 4), and then proceeds to the next step SP6. Incidentally, if the duct stirring motor 94 had already stopped, the control unit 5 continues to keep the duct stirring motor 94 stopped.

[0096] In step SP6, the control unit 5 determines whether the toner cover 21 is blocked or not based on the detection signal obtained from the toner cover detection sensor 23. If a negative result is obtained, the control unit 5 repeats step SP6 and waits for the toner cover 21 to be blocked. On the other hand, if a positive result is obtained in step SP6, this indicates that the user may have replaced the toner cartridge 51 and then blocked the toner cover 21. At this point, the control unit 5 moves to the next step SP7. At this time, each part of the image forming apparatus 2 is in the state shown at time t13 in Figure 6.

[0097] In step SP7, the control unit 5 reads the identification number and various information from the wireless tag 58 of the toner cartridge 51 using the toner cartridge tag reader 77 (Figure 4), and then proceeds to the next step SP8.

[0098] In step SP8, the control unit 5 compares the identification number stored in the flash memory 74 with the identification number read this time to determine whether or not the toner cartridge 51 has been replaced. If a negative result is obtained here, it indicates that the toner cartridge 51 was not replaced for reasons such as the user mistakenly reinserting the toner cartridge 51 that had been removed. At this point, the control unit 5 returns to step SP2 and performs a series of processes to cause the user to replace it with another toner cartridge 51.

[0099] Incidentally, the control unit 5 also determines whether the toner cartridge 51 is compatible with the image forming apparatus 2 based on the identification number and various information read from the wireless tag 58 of the replaced toner cartridge 51. If the control unit 5 determines that the toner cartridge 51 is not compatible with the image forming apparatus 2, it stops the printing process and displays a predetermined message on the display operation unit 6 to prompt the user to replace the toner cartridge 51 again.

[0100] On the other hand, if a positive result is obtained in step SP8, this indicates that the toner cartridge 51 has been replaced with a new toner cartridge 51. At this point, the control unit 5 moves on to the next step SP9.

[0101] In step SP9, the control unit 5 drives the toner supply motor 93 and the duct stirring motor 94 (Figure 4), respectively, and moves to the next step SP10. As a result, in the image forming unit 31 (Figure 3), the toner discharger 57 and the toner supplyer 59 rotate, respectively, supplying the toner from the toner cartridge 51 to the toner storage space 61 of the ID unit 53 via the toner supply duct 52.

[0102] In step SP10, the control unit 5 determines whether the toner level detected by the ID toner detection sensor 62 has reached full, that is, whether new toner has been supplied from the replaced toner cartridge 51 to the ID unit 53. If a negative result is obtained here, it indicates that new toner was not supplied for reasons such as the user mistakenly installing a used toner cartridge 51. At this point, the control unit 5 returns to step SP2 and performs a series of processes to have the user replace it with another toner cartridge 51.

[0103] On the other hand, if a positive result is obtained in step SP10, this indicates that sufficient new toner has been supplied to the toner storage space 61 of the ID unit 53. At this point, the control unit 5 moves on to the next step SP11.

[0104] In step SP11, the control unit 5 continues the current printing process and controls the development voltage control unit 79 to change the development voltage applied to the development roller 64 of the ID unit 53 by an amount corresponding to the low state, increasing the absolute value of the voltage, and then moves to the next step SP12. For example, the control unit 5 changes the development voltage from the normal value of -160[V] to -175[V], which is -15[V] (i.e., a decrease). At this time, each part of the image forming apparatus 2 will be in the state shown at time t14 in Figure 6.

[0105] In step SP12, the control unit 5 displays a message on the display operation unit 6 indicating that the process associated with replacing the toner cartridge 51 has been completed, that is, that the toner shortage has been resolved, and then proceeds to the next step SP13.

[0106] Furthermore, if a negative result is obtained in step SP1, this indicates that the toner level in the ID is not low and the printing process should continue. At this point, the control unit 5 moves to the next step SP13.

[0107] In step SP13, the control unit 5 determines whether the printing process has finished. If a negative result is obtained, the control unit 5 returns to step SP1 and repeats the series of processes. On the other hand, if a positive result is obtained in step SP13, the control unit 5 moves to the next step SP14 and terminates the low state response processing procedure RT1.

[0108] As shown in Figure 6(E), the control unit 5 maintains the operation of the ID motor 90 while executing the low state response processing procedure RT1, thereby allowing the printing process to continue without interruption.

[0109] Incidentally, in step SP11 (i.e., time t14 in Figure 6), the control unit 5 changes the development voltage to -175[V], and then gradually increases the development voltage back to the normal value of -160[V]. For example, the control unit 5 counts the rotation speed of the ID motor 90, and at times t15, t16, and t17, after a predetermined number of rotations (e.g., 500 rotations) has elapsed from time t14 (Figure 6), it changes (increases) the development voltage by +5[V] each time, and finally returns the development voltage to the normal value of -160[V].

[0110] [1-2-2. When the toner level in the ID becomes empty] Next, we will explain the printing process when the toner level in the ID becomes empty. When the control unit 5 receives a print job from the host device 100 (Figure 4) and the printing process is started accordingly, it reads the empty state response program from the flash memory 74 and executes it, thereby starting the empty state response procedure RT2 shown in Figure 7, which corresponds to Figure 5.

[0111] Figure 8, which corresponds to Figure 6, is a timing chart showing the voltage of each part of the image forming apparatus 2, the detection status by each sensor, and the drive status of each motor.

[0112] In the image forming apparatus 2, when the empty state response processing procedure RT2 (Figure 7) is started, the process moves to the first step SP21. In step SP21, the control unit 5 determines whether the toner level detected by the ID toner detection sensor 62 is empty. If a positive result is obtained, this indicates that the toner level is extremely low and printing cannot be continued, requiring the user to replace the toner cartridge 51. At this point, the control unit 5 moves to the next step SP22.

[0113] Incidentally, in this case, the image forming apparatus 2 has gone from a low to an empty state, so when it reaches the low state, the toner supply motor 93 is stopped in step SP3 of the low state response processing procedure RT1 (Figure 5). In other words, at this time, the image forming apparatus 2 has gone from the state at time t21 in Figure 8 to the state at time t22.

[0114] In step SP22, the control unit 5 displays a message on the display operation unit 6 indicating that the toner level in the ID is empty, and then proceeds to the next step SP23. This message notifies the user that the printing process may be interrupted soon because the toner cartridge 51 is empty, and encourages them to replace it with a new toner cartridge 51.

[0115] Subsequently, in steps SP23 to SP30, the control unit 5 continues the current printing process and performs the same processing as steps SP3 to SP10 of the low state response processing procedure RT1 (Figure 5). At this time, if a positive result is obtained in step SP24, the image forming apparatus 2 will be in the state shown at time t23 in Figure 8. Also, if a positive result is obtained in step SP26, the image forming apparatus 2 will be in the state shown at time t24 in Figure 8. Then, if a positive result is obtained in step SP30, the control unit 5 moves to the next step SP31.

[0116] In step SP31, the control unit 5 continues the current printing process and controls the development voltage control unit 79 to change the development voltage applied to the development roller 64 of the ID unit 53 by an amount corresponding to the empty state, in the direction of increasing the absolute value of the voltage, and then moves to the next step SP32. For example, the control unit 5 changes (i.e., decreases) the development voltage from the normal value of -160[V] by -30[V] to -190[V]. At this time, each part of the image forming apparatus 2 will be in the state shown at time t25 in Figure 8.

[0117] Subsequently, in steps SP32 to SP34, the control unit 5 performs the same processing as steps SP12 to SP14 of the low state response processing procedure RT1 (Figure 5), and then terminates the empty state response processing procedure RT2.

[0118] Incidentally, in step SP31 (i.e., time t25 in Figure 8), the control unit 5 changes the development voltage to -190[V], and then, similar to when the low state response processing procedure RT1 is completed, gradually increases the development voltage back to the normal value of -160[V]. For example, the control unit 5 counts the rotation speed of the ID motor 90, and at time points t26, t27, and t28, etc., after a predetermined number of rotations (e.g., 500 rotations) has elapsed from time t25 (Figure 8), it changes (increases) the development voltage by +5[V] each time, and finally returns the development voltage to the normal value of -160[V].

[0119] [1-3. Effects, etc.] In the above configuration, the image forming system 1 according to the first embodiment is configured so that the toner cartridge 51 of the image forming unit 31 can be attached to and detached by the user when the toner cover 21 of the image forming apparatus 2 is open (Figure 2).

[0120] If the toner level in the ID detected by the toner detection sensor 62 in each image forming unit 31 becomes low or empty during the printing process, the image forming apparatus 2 will continue the printing process and prompt the user to replace the toner cartridge 51. At this time, when the image forming apparatus 2 detects that new toner has been stored in the toner storage space 61 of the ID unit 53 due to the replacement of the toner cartridge 51, it changes the development voltage applied to the development roller 64.

[0121] This allows the image forming system 1 to replenish toner while the image forming apparatus 2 continues printing, and effectively suppresses changes in image quality caused by the difference in the electrostatic charge of the newly supplied toner compared to before supply. In other words, the image forming system 1 can replenish toner without interrupting the printing process by the image forming apparatus 2, while suppressing a decrease in image quality, and continue the printing process.

[0122] Incidentally, in general electrophotographic image forming apparatuses, for example, an ID unit is detachable from the housing in the image forming section for each color, and a toner cartridge is detachable from the ID unit. In such image forming apparatuses, from the standpoint of protecting the user, if the housing cover is opened during printing, the operation of the ID unit is stopped and the printing operation is interrupted.

[0123] Furthermore, in such image forming apparatuses, various correction processes may be performed at times such as immediately after startup or after the toner cartridge has been replaced. These correction processes include density correction, which corrects the density of the toner, and color misalignment correction, which corrects the misalignment of the printing position in the toner images of each color. In density correction, for example, a predetermined toner image is formed in each image forming unit and transferred to an intermediate transfer belt, the density of the toner in the toner image is detected by a predetermined sensor, and the density of the toner in each image forming unit is corrected based on the detected density value.

[0124] However, when performing various correction processes such as density correction in an image forming apparatus, it becomes necessary to remove the paper P from the transport path, and if printing is in progress, it becomes necessary to interrupt the printing process. For this reason, especially when printing an image on paper P drawn from a long roll of paper RP, as in the image forming system 1 (Figure 1), it becomes necessary to remove the paper P from the transport path and to set the paper P again after the density correction process is completed, which could be a significant burden for the user.

[0125] In contrast, the image forming system 1 according to the first embodiment allows the toner cartridge 51 to be replaced by opening the toner cover 21 while the ID unit 53 is installed and the printing process is continuing. Furthermore, the image forming system 1 reduces the development voltage when the toner cartridge 51 is replaced. As a result, the image forming system 1 allows the toner cartridge 51 to be replaced while the printing process continues, without requiring the user to perform any work related to the paper P.

[0126] Furthermore, in the image forming system 1, the degree of change in the development voltage when the toner cartridge 51 is replaced is set to a value corresponding to the remaining toner in the ID before replacement. Specifically, in the image forming system 1, if the remaining toner in the ID before replacement is low, the development voltage is changed by -15[V], and if it is empty, it is changed by -30[V].

[0127] As a result, in the image forming system 1, after replacing the toner cartridge 51, a developing voltage suitable for the charge properties of the toner stored in the toner storage space 61 of the ID unit 53 can be applied to the developing roller 64, thereby enabling proper development of the electrostatic latent image formed on the photoreceptor drum 66. In other words, in the image forming system 1, when the toner cartridge 51 is replaced, the ease of movement of the toner decreases due to the decrease in charge properties. By increasing the absolute value of the developing voltage, the ease of movement of the toner can be controlled to increase, and as a result, a decrease in image quality can be avoided.

[0128] From another perspective, the image forming system 1 can effectively suppress the degradation of image quality in printed images by appropriately changing the development voltage without performing density correction processing. Therefore, the image forming system 1 can continue printing without interruption when the toner cartridge 51 is replaced.

[0129] With the above configuration, in the image forming system 1 according to the first embodiment, if the toner level in the ID becomes low or empty while the image forming apparatus 2 is performing the printing process, the user is instructed to open the toner cover 21 and replace the toner cartridge 51 while the printing process continues. Furthermore, once the toner cartridge 51 has been successfully replaced, the image forming apparatus 2 changes the development voltage applied to the development roller 64 to a lower value. As a result, the image forming system 1 can replenish toner in the image forming apparatus 2 without interrupting the printing process, and can effectively suppress changes in image quality due to differences in the electrostatic properties of the newly supplied toner.

[0130] [2. Second Embodiment] The image forming system 201 according to the second embodiment differs from the image forming system 1 according to the first embodiment in that it has an image forming apparatus 202 instead of an image forming apparatus 2, but is otherwise configured similarly.

[0131] The image forming apparatus 202 differs from the image forming apparatus 2 according to the first embodiment in that it has a control unit 205 instead of the control unit 5, but is otherwise configured similarly. The control unit 205 is configured similarly to the control unit 5 (Figure 4) in the first embodiment, but the information and programs stored in the flash memory 74 differ in some respects from those of the control unit 5.

[0132] In this image forming apparatus 202, the replacement of the toner cartridge 51 is performed in a manner that differs in part from that of the first embodiment. When the control unit 205 receives a print job from the host device 100 (Figure 4) and the printing process is started accordingly, it reads the toner cartridge replacement response program from the flash memory 74 and executes it, thereby starting the toner cartridge replacement response procedure RT3 shown in Figure 9, which corresponds to Figures 5 and 7, and proceeds to the first step SP41.

[0133] In step SP41, the control unit 205 determines whether the toner level detected by the toner detection sensor 62 is full. If a negative result is obtained, this indicates a low or empty state, and since the toner will soon run out and printing will not be able to continue, it is advisable for the user to replace the toner cartridge 51. At this point, the control unit 205 moves to the next step SP42.

[0134] In step SP42, the control unit 205 determines whether the toner level in the ID is low. If a positive result is obtained, this indicates that the user should be prompted to replace the toner cartridge 51 and that processing corresponding to the low level should be performed. At this point, the control unit 205 moves to the next step SP43.

[0135] In step SP43, the control unit 205 performs a low-condition toner cartridge replacement process as a subroutine and then moves to the next step SP52. This low-condition toner cartridge replacement process performs the same processing as steps SP2 to SP12 of the low-condition response processing procedure RT1 (Figure 5) in the first embodiment.

[0136] On the other hand, if a negative result is obtained in step SP42, this indicates that the toner level in the ID is empty, and that the user should be prompted to replace the toner cartridge 51 and that processing should be carried out according to the empty state. At this point, the control unit 205 moves to the next step SP44.

[0137] In step SP44, the control unit 205 performs an empty toner cartridge replacement process as a subroutine and then moves to the next step SP52. This empty toner cartridge replacement process performs the same processing as steps SP22 to SP32 of the empty state response processing procedure RT2 (Figure 7) in the first embodiment.

[0138] On the other hand, if a positive result is obtained in step SP41, this indicates that there is sufficient toner remaining and therefore there is no need to immediately replace the toner cartridge 51, but the user may choose to replace the toner cartridge 51. At this point, the control unit 205 moves to the next step SP45.

[0139] In step SP45, the control unit 205 determines whether the toner cover 21 has been opened based on the detection signal obtained from the toner cover detection sensor 23. If a negative result is obtained, the control unit 205 returns to step SP41 and repeats the series of processes. On the other hand, if a positive result is obtained in step SP45, this indicates that the user may have the intention to open the toner cover 21 and replace the toner cartridge 51. At this point, the control unit 205 moves to the next step SP46.

[0140] In step SP46, the control unit 205 stops the toner supply motor 93 and the duct stirring motor 94 (Figure 4), thereby stopping the toner delivery unit 57 in the toner cartridge 51 (Figure 3) and the toner supply unit 59 in the toner supply duct 52, and then proceeds to the next step SP47.

[0141] In step SP47, the control unit 205 determines whether the toner cover 21 is blocked based on the detection signal obtained from the toner cover detection sensor 23. If a negative result is obtained, the control unit 205 repeats step SP47 and waits for the toner cover 21 to be blocked. On the other hand, if a positive result is obtained in step SP47, this indicates that the user may have replaced the toner cartridge 51 and then blocked the toner cover 21. At this point, the control unit 205 moves to the next step SP48.

[0142] In step SP48, the control unit 205 reads the identification number and various information from the wireless tag 58 of the toner cartridge 51 using the toner cartridge tag reader 77 (Figure 4), and then proceeds to the next step SP49.

[0143] In step SP49, the control unit 205 determines whether the toner cartridge 51 has been replaced by comparing the identification number stored in the flash memory 74 with the identification number read this time. If a negative result is obtained here, it means that the toner cartridge 51 has not been replaced, for example, if the user accidentally opened the toner cover 21 but then closed the toner cover 21. At this point, the control unit 5 moves on to the next step SP52.

[0144] On the other hand, if a positive result is obtained in step SP49, this indicates that the toner cartridge 51 was replaced with a new toner cartridge 51 while the toner cover 21 was open. At this point, the control unit 205 moves on to the next step SP50.

[0145] In step SP50, the control unit 205 determines, based on the read identification number and various other information, whether the replaced toner cartridge 51 is a model compatible with the image forming apparatus 202. If a positive result is obtained, this indicates that the replaced toner cartridge 51 is of the appropriate model and there is no risk of disruption to the currently running printing process. At this point, the control unit 205 proceeds to the next step SP51.

[0146] In step SP51, the control unit 205 drives the toner supply motor 93 and the duct stirring motor 94 (Figure 4), respectively, and then moves to the next step SP52. As a result, in the image forming unit 31 (Figure 3), the toner discharger 57 and the toner supplyer 59 rotate, respectively, supplying the toner from the toner cartridge 51 to the toner storage space 61 of the ID unit 53 via the toner supply duct 52.

[0147] Incidentally, in the toner storage space 61, since a sufficient amount of toner is stored inside at this time, the proportion of newly supplied toner is low, and the electrostatic charge of the toner does not fluctuate significantly.

[0148] In step SP52, the control unit 205 determines whether the printing process is complete or not. If a negative result is obtained, the control unit 205 returns to step SP41 and repeats the series of processes. On the other hand, if a positive result is obtained in step SP52, the control unit 205 then moves to the next step SP55.

[0149] On the other hand, if a negative result is obtained in step SP50, this indicates that continuing the printing process may result in the inability to form a normal toner image or may cause a malfunction of the image forming apparatus 202. At this point, the control unit 205 moves on to the next step SP53.

[0150] In step SP53, the control unit 205 displays a message on the display operation unit 6 indicating that the replaced toner cartridge 51 is not compatible with the image forming apparatus 202 and that the printing process will be stopped to prevent malfunctions, and then proceeds to the next step SP54.

[0151] In step SP54, the control unit 205 stops the ongoing printing process and moves to the next step SP55. In step SP55, the control unit 205 terminates the toner cartridge replacement processing procedure RT3.

[0152] In the above configuration, in the image forming system 201 according to the second embodiment, even if the toner level in the ID is full in the image forming apparatus 202, the toner cartridge 51 can be replaced while the printing process continues if the toner cover 21 is opened by the user.

[0153] In this case, the image forming system 201 maintains good image quality without changing the development voltage or performing density correction processing, because the charge of the toner stored in the toner storage space 61 of the ID unit 53 does not change significantly.

[0154] On the other hand, in the image forming system 201, if the toner level in the ID becomes low or empty, the toner cartridge 51 is replaced while the printing process continues, and the development voltage is changed, similar to the first embodiment. Therefore, good image quality can be maintained without performing density correction processing.

[0155] In other respects as well, the image forming system 201 according to the second embodiment can achieve the same effects as the image forming system 1 according to the first embodiment.

[0156] [3. Other Embodiments] In the first embodiment described above, the development voltage is lowered when the toner level in the ID becomes low during the printing process and the toner cartridge 51 is replaced by the user. However, the present invention is not limited to this, and for example, the charging voltage applied to the charging roller 67 may be lowered, or the supply voltage applied to the supply roller 63 may be lowered, or the amount of exposure energy (i.e., voltage value, current value, etc.) supplied to the exposure head 54 may be increased. In short, the values ​​of each part should be adjusted so that a toner image can be appropriately formed using the toner when new toner is supplied to the toner storage space 61 of the ID unit 53 and the chargeability of the stored toner decreases. The same applies to the second embodiment.

[0157] Furthermore, in the first embodiment described above, we described a configuration in which only the development voltage is changed when the toner level in the ID becomes low during the printing process and the toner cartridge 51 is replaced by the user. However, the present invention is not limited to this, and for example, the voltage difference between the development voltage and the charging voltage may be maintained by changing both the development voltage and the charging voltage, or the voltage difference between the development voltage and the supply voltage may be maintained by changing both the development voltage and the supply voltage. The same applies to the second embodiment.

[0158] Furthermore, in the first embodiment described above, a configuration was described in which the development voltage is reduced by -15[V] from the normal level if the toner level in the ID is low, and by -30[V] from the normal level if the toner level in the ID is empty. However, the present invention is not limited to this, and the development voltage may be reduced by various other voltages, for example, by -20[V] from the normal level if the toner level is low, and by -40[V] from the normal level if the toner level is empty. The same applies to the second embodiment.

[0159] Furthermore, in the first embodiment described above, two stages are detected for cases other than full toner in the ID: low or empty. The mode of development is increased when the amount of toner remaining in the ID is lower. However, the present invention is not limited to this. For example, the number of stages for detecting the amount of toner remaining in the ID may be set to three or more, and the degree of decrease in development voltage may be increased as the detected amount of toner remaining in the ID decreases. Alternatively, the number of stages for detecting the amount of toner remaining in the ID may be set to one or two or more, while the degree of decrease in development voltage may be set to only one stage (i.e., a fixed value). Also, if the amount of toner remaining in the ID can be detected as a numerical value, the development voltage may be reduced by the voltage calculated using that numerical value. The same applies to the second embodiment.

[0160] Furthermore, in the first embodiment described above, after changing the development voltage to -175[V] by the low state response processing procedure RT1 (Figure 5), the development voltage is changed by +5[V] each time the ID motor 90 rotates for a predetermined number of revolutions (e.g., 500 revolutions), gradually returning to the normal value of -160[V]. However, the present invention is not limited to this, and the development voltage may be gradually changed based on various values ​​that are roughly proportional to the amount of toner supplied to the toner storage space 61 (Figure 3) of the ID unit 53, such as the rotation speed of the photoreceptor drum 66, the number of pages printed, or the dot count. Alternatively, if a stirring member for stirring the toner is provided in the toner storage space 61 of the ID unit 53, the operating time of the stirring member may be used as a reference. Also, the range of change in the development voltage is not limited to +5[V], but may be various other values ​​such as +3[V] or +10[V]. Alternatively, the range of change in the development voltage may not be constant, but may be a different value from time to time based on a predetermined function or a value stored in a predetermined table. Furthermore, the development voltage changed in the low state processing procedure RT1 may be maintained as is. The same applies to the empty state processing procedure RT2 (Figure 7) and the second embodiment.

[0161] Furthermore, in the first embodiment described above, in step SP10 of the low state response processing procedure RT1 (Figure 5), if it is confirmed that the toner level in the ID has reached full after the replacement of the toner cartridge 51, the development voltage is changed, assuming that the toner cartridge 51 has been correctly replaced with a new one. However, the present invention is not limited to this, and for example, if it is detected that the toner cartridge 51 has been replaced with a different one than before based on tag information, the development voltage may be changed regardless of the toner level in the ID. The same applies to the empty state response processing procedure RT2 (Figure 7), and also to the second embodiment.

[0162] Furthermore, in the first embodiment described above, in the empty state response processing procedure RT2 (Figure 7), the toner level in the ID becomes empty, and in step SP22, a predetermined message is displayed on the display operation unit 6 to prompt the user to replace the toner cartridge 51, and the printing process continues. However, the present invention is not limited to this, and for example, the printing process may be stopped if the toner level in the ID decreases further from the empty state. The same applies to the second embodiment.

[0163] Furthermore, in the first embodiment described above, a configuration was described in which density correction processing is not performed after the replacement of the toner cartridge 51. However, the present invention is not limited to this, and density correction processing may be performed at times when the printing process is interrupted due to various factors, such as when the printing process based on one print job is completed or when all the paper P has been pulled out from the roll paper RP and a new roll paper RP is replaced. The same applies to the second embodiment.

[0164] Furthermore, in the first embodiment described above, a toner cover 21 that can be opened and closed is provided on the housing 20 of the image forming apparatus 2, and when the toner cover 21 is closed, the attachment and detachment of the toner cartridge 51 is prohibited, while when the toner cover 21 is open, the attachment and detachment of the toner cartridge 51 is permitted. However, the present invention is not limited to this, and for example, the toner cover 21 may be omitted from the housing 20 of the image forming apparatus 2, while a locking claw or the like is provided to prohibit (lock) or permit (unlock) the attachment and detachment of the toner cartridge 51, and the state of the locking claw may be changed by a predetermined actuator or the like, or by the user's manual operation. In this case, for example, in steps SP4 and SP6 of the low state response processing procedure RT1 (Figure 5), the change in the state of the locking claw can be detected by a sensor or the like. The same applies to the second embodiment.

[0165] Furthermore, in the above-described embodiment, a configuration was described in which wireless communication is performed between a toner cartridge tag reader 77 provided in the housing 20 of the image forming apparatus 2 and a wireless tag 58 provided on the toner cartridge 51, and the replacement of the toner cartridge 51 is detected by comparing the read identification numbers. However, the present invention is not limited to this, and for example, a predetermined electrical connection terminal may be provided on the toner cartridge 51, and an electrical connection may be made with the electrical connection terminal provided in the housing 20 of the image forming apparatus 2, and information may be read from the IC chip on the toner cartridge 51 side. Alternatively, for example, only the insertion and removal of the toner cartridge 51 may be detected by a predetermined sensor, and when the remaining toner in the ID unit's toner storage space 61 becomes full after the insertion and removal of the toner cartridge 51, it may be determined that the toner cartridge 51 has been replaced, and the developing voltage may be changed. The same applies to the second embodiment.

[0166] Furthermore, in the first embodiment described above, the image forming apparatus 2 (Figure 1) was described in which each image forming unit 31 was arranged in the order of yellow (Y), cyan (C), magenta (M), black (K), and white (W) from the rear. However, the present invention is not limited to this, and various other orders are also possible. The same applies to the second embodiment.

[0167] Furthermore, in the first embodiment described above, a configuration was described in which five image forming units 31 are provided in the image forming apparatus 2 (Figure 1). However, the present invention is not limited to this, and four or fewer, or six or more, image forming units 31 may be provided.

[0168] Furthermore, in the first embodiment described above, the image forming apparatus 2 is configured in a so-called intermediate transfer method, in which the toner images formed by each image forming unit 31 are first transferred to the intermediate transfer belt 45, and the toner images are then transferred from the intermediate transfer belt 45 to the paper P in the secondary transfer unit 48. However, the present invention is not limited to this, and for example, the image forming apparatus 2 may be configured in a so-called direct transfer method, in which the toner images are directly transferred from each image forming unit 31 to the paper P. The same applies to the second embodiment.

[0169] Furthermore, in the first embodiment described above, the image forming system 1 (Figure 1) is configured to combine the image forming apparatus 2 with a continuous paper supply device 3 and a winding device 4, and to perform printing on a long sheet of paper P drawn from a roll of paper RP. However, the present invention is not limited to this, and for example, paper P made of cut sheets such as A3 or A4 size may be stored in a tray 26 in advance, printing may be performed on the paper P, and then transported to a paper output tray 36 for accumulation. In this case, the continuous paper supply device 3 and the winding device 4 can be omitted. The same applies to the second embodiment.

[0170] Furthermore, in the embodiments described above, we have described a configuration in which the image forming apparatus 2 is configured as a single-function printer. However, the present invention is not limited to this, and the image forming apparatus 2 may be configured as, for example, an MFP (Multi-Function Peripheral) having the functions of a copier or a facsimile machine. The same applies to the second embodiment.

[0171] Furthermore, the present invention is not limited to the embodiments described above and other embodiments. That is, the scope of application of the present invention extends to embodiments that arbitrarily combine some or all of the embodiments described above and other embodiments, or embodiments that extract some of them. The scope of application of the present invention also extends when a part of the configuration described in any embodiment among the embodiments described above and other embodiments is extracted and replaced or adapted with a part of the configuration of any embodiment among the embodiments described above and other embodiments, or when the extracted part of the configuration is added to any embodiment.

[0172] Furthermore, in the above-described embodiment, an image forming apparatus 2 was described in which a toner cartridge 51 as a developer container, an ID unit 53 as an image forming unit, a toner cartridge tag reader 77 as a replacement detection unit, and a control unit 5 as a control unit were configured. However, the present invention is not limited to this, and an image forming apparatus may be configured with a developer container, an image forming unit, a replacement detection unit, and a control unit having various other configurations. [Industrial applicability]

[0173] This invention can be used, for example, in an electrophotographic printer. [Explanation of Symbols]

[0174] 1, 201...Image forming system, 2, 202...Image forming apparatus, 3...Continuous paper supply device, 4...Winding device, 5, 205...Control unit, 6...Display operation unit, 20...Housing, 21...Toner cover, 23...Toner cover detection sensor, 30...Intermediate transfer unit, 31...Image forming unit, 51...Toner cartridge, 52...Toner supply duct, 53...ID unit, 54...Exposure head, 55...Primary transfer roller, 57...Toner dispenser, 58...Wireless tag, 5 9...Toner supply unit, 60...ID unit housing, 61...Toner storage space, 62...ID internal toner detection sensor, 63...Supply roller, 64...Developing roller, 66...Photoconductor drum, 67...Charging roller, 77...Toner cartridge tag reader, 79...Developing voltage control unit, 80...Supply voltage control unit, 81...Charging voltage control unit, 82...Exposure control unit, 93...Toner supply motor, 94...Duct stirring motor, P...Paper, RP...Roll paper, W...Conveyor path.

Claims

1. A developer container, which is detachably attached to the main body of the device and contains the developer, An image forming unit that transfers the developer supplied from the developer container to an image carrier for development, A replacement detection unit for detecting the replacement of the developer container, When the replacement detection unit detects that the developer container has been replaced, the control unit controls the image forming unit to increase the ease with which the developer can move compared to before the developer container was replaced. An image forming apparatus characterized by comprising the following:

2. The aforementioned image forming unit is The image carrier comprises an electrostatic latent image forming unit that forms an electrostatic latent image, A developer carrier is subjected to a development voltage controlled by a development voltage control unit, and the developer is applied to the image carrier in accordance with the electrostatic latent image to develop it. Furthermore, When the replacement detection unit detects that the developer container has been replaced, the control unit controls the developer voltage control unit to increase the absolute value of the developer voltage compared to before the developer container was replaced. The image forming apparatus according to feature 1.

3. The image forming unit further comprises a supply unit to which a supply voltage controlled by a supply voltage control unit is applied and to which the developer is supplied to the developer carrier, When the control unit detects that the developer container has been replaced, it controls the developer voltage control unit and the supply voltage control unit to increase the absolute value of the developing voltage compared to before the developer container was replaced, and to maintain the voltage difference between the developing voltage and the supply voltage. The image forming apparatus according to feature 2.

4. The image forming unit is A charging voltage controlled by the charging voltage control unit is applied to charge the image carrier. Furthermore, When the replacement detection unit detects that the developer container has been replaced, the control unit controls the developer voltage control unit and the charging voltage control unit to increase the absolute value of the developing voltage compared to before the developer container was replaced, and to maintain the voltage difference between the developing voltage and the charging voltage. The image forming apparatus according to feature 2.

5. The image forming unit is A charging voltage controlled by a charging voltage control unit is applied to a charging body that charges the image carrier, An electrostatic latent image forming unit that forms an electrostatic latent image on the image carrier charged by the charged body, A developer carrier that applies the developer to the image carrier in accordance with the electrostatic latent image and develops the image. Furthermore, When the replacement detection unit detects that the developer container has been replaced, the control unit controls the charging voltage control unit to increase the absolute value of the charging voltage compared to before the developer container was replaced. The image forming apparatus according to feature 1.

6. An electrostatic latent image forming unit that exposes the image carrier to form an electrostatic latent image using an energy amount controlled by the exposure control unit. Furthermore, The image forming unit further comprises a developer carrier that applies the developer to the image carrier in accordance with the electrostatic latent image and develops it. When the replacement detection unit detects that the developer container has been replaced, the control unit controls the exposure control unit to increase the amount of energy used by the electrostatic latent image forming unit to expose the image carrier, compared to before the developer container was replaced. The image forming apparatus according to feature 1.

7. The image forming unit is A developer storage section for storing the developer supplied from the developer container, A remaining amount detection unit for detecting the remaining amount of developer contained in the developer storage unit and Furthermore, When the replacement detection unit detects that the developer container has been replaced, the control unit controls the degree to which the ease of movement of the developer is increased in the image forming unit, adjusting it according to the remaining amount of the developer detected by the remaining amount detection unit. The image forming apparatus according to any one of claims 1 to 6.

8. The remaining amount detection unit is, The system detects a "low state," which indicates a relatively small amount of developer remaining in the developer storage section but still allows development with the developer, and an "empty state," which indicates an extremely small amount of developer remaining in the developer storage section making development impossible. The control unit, The image forming unit controls the degree to which it increases the ease of movement of the developer when it detects an empty state compared to when it detects a low state. The image forming apparatus according to feature 7.

Images