JP2007025385A - Powder conveying device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of suppressing a decrease in detection precision of the remaining amount of toner by fixing toner in a nozzle 235 to an internal wall of a transparent pipe 235c of the nozzle 235. <P>SOLUTION: The image forming apparatus which is equipped with a toner storage container 260 containing toner, the nozzle 235 for receiving and guiding toner discharged therefrom toward a conveyance destination, the transparent pipe 235c provided in at least a lengthwise portion in the nozzle 235, a transmission type optical sensor 250 detecting the quantity of light transmitted through the transparent pipe 235c from one end side to the other end side in a nozzle cross-sectional direction, and a suction pump 210 which sucks the toner in the nozzle 235, and the image forming apparatus conveying the toner in the toner storage container 260 to a developing device 50 is provided with an air supply section 280 as an in-pipe air supply means of sending air toward the internal wall of the transparent pipe 235c of the nozzle 235. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a powder conveyance device that conveys powder discharged from a powder container to a conveyance destination through a conveyance tube, and an image forming apparatus such as a copying machine, a facsimile, and a printer including the same.

  Conventionally, an image forming apparatus that forms a toner image on a recording member such as transfer paper by an electrophotographic method or a direct recording method is known. The electrophotographic method is a method in which toner is attached to a latent image formed on a latent image carrier such as a photoconductor to form a toner image on the latent image carrier. In addition, the direct recording method, for example, as in the image forming apparatus described in Patent Document 1, the toner group that has been ejected from the toner flying device is directly attached to the recording body regardless of the latent image carrier, and the toner image is formed. It is a method to form. In an image forming apparatus employing these methods, it is necessary to replenish toner to a developing device or a toner flying device as the image is formed. Therefore, there is also known an image forming apparatus that replenishes toner to a developing device or the like by driving a toner conveying device that conveys toner discharged from the toner container to a developing device or the like through a conveying tube. .

  For example, Patent Document 2 discloses a toner conveying device having such a configuration. The toner conveying device includes a toner container for containing toner, a suction pump for sucking powdered toner, a conveying pipe having one end connected to the toner container and the other end connected to a suction port of the suction pump, have. By operating the suction pump, the toner in the transport pipe is sucked into the suction pump and discharged into the developing unit, and the toner in the toner container is sucked into the transport pipe. With such a mechanism, the toner in the toner container can be supplied into the developing device. Further, the toner conveying device grasps the toner remaining amount in the toner container with the following configuration. That is, two transparent windows facing each other through the pipe are formed in the vicinity of the toner container in the length direction of the transport pipe. An optical sensor is disposed outside the transport tube in such a posture as to sandwich the two transparent windows. This optical sensor allows light emitted from the light emitting element to enter the transport tube through one transparent window. Then, the amount of transmitted light that passes through the inside of the transport tube in the cross-sectional direction and exits from the other transparent window is detected by the light receiving element. The amount of transmitted light detected in this way correlates with the remaining amount of toner in the toner container. This is because as the remaining amount of toner decreases, the toner density in the transport tube decreases and the amount of transmitted light increases. The toner conveying device is configured to grasp the remaining amount of toner in the toner container based on the behavior of the transmitted light amount.

JP 2002-307737 A JP 2004-4394 A

  However, in the configuration for grasping the remaining amount of toner in this way, when the toner in the transport tube is fixed to the inner wall of the transparent window, the amount of transmitted light is reduced regardless of the remaining amount of toner. It will interfere. This decrease in detection accuracy is a problem that occurs in a toner transport device that transports toner as powder, but a similar problem may occur in a powder transport device that transports powder different from toner.

  The present invention has been made in view of the above background, and an object of the present invention is to provide the following powder conveying apparatus and an image forming apparatus using the same. That is, it is a powder conveyance device or the like that can suppress a decrease in the accuracy of detecting the remaining amount of powder due to the powder in the conveyance tube being fixed to the inner wall of a light transmitting portion such as a transparent window in the conveyance tube.

In order to achieve the above object, the invention of claim 1 includes a powder container for storing powder, and a transport pipe for receiving the powder discharged from the powder container and guiding it to a transport destination. , A light transmission portion provided at least in part in the length direction of the transport tube, and the amount of light transmitted from the one end side to the other end side in the cross-sectional direction of the transport tube with respect to the light transmission portion And an optical sensor for detecting the movement of the powder in the powder container, and a moving force applying means for applying a moving force from the powder container side toward the transfer destination side of the powder in the transfer tube. In the powder conveying apparatus for conveying a body through the conveying pipe to the conveying destination, an in-pipe air feeding means for feeding air toward the inner wall of the light transmitting portion of the conveying pipe is provided. is there.
Further, the invention according to claim 2 is the powder conveying apparatus according to claim 1, wherein the portion closer to the conveying destination side than the light transmitting portion in the length direction of the conveying tube includes the inner tube and the inner tube. A double structure pipe having an outer pipe, an air supply pipe of the in-pipe air supply means connected to an opening provided in the outer pipe, and the transport destination side of the double structure pipe with respect to the opening The gap between the inner tube and the outer tube is closed over the entire circumference in the tube circumferential direction at a location approaching the position.
The invention of claim 3 is the powder transport apparatus of claim 2, wherein the light transmitting portion has a structure with a smaller inner diameter from the transport destination side toward the powder container side. It is characterized by.
According to a fourth aspect of the present invention, in the powder conveying device according to the first aspect, the portion closer to the powder container side than the light transmitting portion in the length direction of the conveying tube A double structure tube including an outer tube to be included, and an air supply pipe of the in-pipe air supply means is connected to an opening provided in the outer pipe, and the powder is more than the opening in the double structure pipe The gap between the inner tube and the outer tube is closed over the entire circumference in the tube circumferential direction at a location approaching the body container side.
Further, the invention of claim 5 is the powder conveying apparatus of claim 4, wherein a second opening is provided at a location closer to the powder container side than the opening in the outer tube, and the opening and the second The gap is closed over the entire circumference in the pipe circumferential direction at a position between the opening and one of a plurality of branch pipes obtained by branching the air supply pipe into a plurality of openings is connected to the opening, and the other One of these is connected to the second opening.
The invention according to claim 6 is the powder conveying apparatus according to claim 4 or 5, wherein the light transmitting portion has a structure in which an inner diameter is reduced from the powder container side toward the conveying destination side. It is characterized by the fact that
The invention according to claim 7 is the powder conveying apparatus according to claim 5 or 6, wherein an electromagnetic valve is provided in each of the plurality of branch pipes.
Further, the invention of claim 8 is an image forming means for forming an image by attaching toner as powder to a recording member, and a toner transport for transporting toner contained in a powder container to the image forming means. In an image forming apparatus comprising an apparatus and a conveyance control means for controlling the apparatus, the powder conveyance device according to any one of claims 1 to 7 is used as the toner conveyance device, and based on a detection result by the optical sensor, The conveyance control means is configured to calculate the remaining amount of toner in the powder container.
According to a ninth aspect of the present invention, in the image forming apparatus according to the eighth aspect, the conveyance control means is controlled so as to perform control for driving the in-pipe air supply means for a predetermined time prior to the calculation of the remaining amount of toner. It is characterized by comprising.

  In these inventions, powder is prevented from sticking to the inner wall of the light transmitting portion by sending air to the inner wall of the light transmitting portion by the air supply means in the tube. A decrease in the amount detection accuracy can be suppressed.

Next, an embodiment of an electrophotographic color laser printer (hereinafter simply referred to as a printer) will be described as an image forming apparatus to which the present invention is applied.
First, the basic configuration of the printer according to this embodiment will be described. FIG. 1 is a schematic configuration diagram illustrating a printer according to the present embodiment. This printer includes four sets of toner image forming units 100Y, 100M, 100C, and 100K for forming images of each color of yellow (Y), magenta (M), cyan (C), and black (K). . Also provided are an optical writing unit 110, paper feed cassettes 120 and 130, a registration roller pair 140, a transfer device 150, a belt fixing type fixing device 170, a stack unit 180, and the like. Furthermore, a toner conveying device, a waste toner bottle (not shown), a power supply unit, and the like are also provided. Hereinafter, the subscripts Y, M, C, and K of the respective symbols indicate members for yellow, magenta, cyan, and black, respectively.

  The optical writing unit 110 includes a light source composed of four laser diodes corresponding to each color of Y, M, C, and K, a regular hexahedral polygon mirror, a polygon motor for rotationally driving the polygon mirror, an fθ lens, a lens, and a reflection mirror. Etc. The laser beam L emitted from the laser diode reaches the surface of the photoreceptor while being reflected by any one surface of the polygon mirror and deflected as the polygon mirror rotates. Then, the photosensitive member surface is optically scanned in the axial direction.

  The toner image forming units 100Y, 100M, 100C, and 100K include drum-shaped photoconductors 2Y, 2M, 2C, and 2K as latent image carriers. These photoconductors 2Y, 2M, 2C, and 2K are drums having a diameter of about 30 [mm] in which an organic photosensitive layer is covered with an element tube made of aluminum or the like. It is driven to rotate clockwise in the figure at high speed. Then, it is optically scanned in the dark by the above-mentioned optical writing unit 110 that emits laser light L modulated based on image information sent from a personal computer (not shown) or the like, and static for Y, M, C, and K. Carries an electrostatic latent image.

  FIG. 2 is an enlarged configuration diagram showing the Y toner image forming unit 100Y together with a part of the transfer device 150 among the four toner image forming units 100Y, 100M, 100C, and 100K. The other toner image forming units (100M, C, K) have the same configuration as that for Y except that the colors of the toners to be used are different from each other. . In the drawing, the toner image forming unit 100Y includes a process unit 1Y and a developing device 50Y. In addition to the photoreceptor 2Y, the process unit 1Y includes a brush roller 3Y for applying a lubricant, a swingable counter blade 4Y for performing a cleaning process, a charge removal lamp 5Y for performing a charge removal process, and the like. Yes. Further, a charging roller 10Y for uniformly charging the photoreceptor 2Y and a roller cleaning device 20Y for cleaning the surface of the charging roller 10Y are also provided.

  In the process unit 1Y, a charging roller 10Y to which an AC charging bias is applied by a power source (not shown) includes a shaft member 11Y, an abutment roller 12Y, a discharge member 13Y, and the like. The shaft member 11Y serves as a core of the charging roller 10Y, and both ends of the shaft member 11Y are rotatably supported by bearings (not shown). A charging bias in which an AC bias is superimposed on a DC bias is applied to the shaft member 11Y by a power source (not shown). The surface of the central portion in the axial direction of the shaft member 11Y is covered with a discharge member 13Y covered with a conductive material over the entire circumference in the axial circumferential direction. Ring-shaped abutment rollers 12Y made of an insulating material are fixed by press-fitting and adhesion in the vicinity of both ends of the shaft member 11Y so as to sandwich the charging roller member 13Y. The outer diameter of these butting rollers 12Y is several tens to 100 [μm] larger than the outer diameter of the discharge member 13Y. The charging roller 10Y makes the discharge member 13Y face the photoconductor 2Y with a predetermined charging gap while the abutting roller 12Y is in contact with the photoconductor 2Y. Then, the surface of the photoreceptor 2Y is uniformly charged by the discharge from the discharge member 13Y while being rotated so that the surface thereof is moved in the direction opposite to the surface movement of the photoreceptor 2Y by a driving means (not shown). When the laser beam L modulated and deflected by the above-described optical writing unit (reference numeral 110 in FIG. 1) is scanned on the surface of the photoreceptor 2Y that is uniformly charged in this way, an electrostatic latent image is formed on the surface. An image is formed.

  The developing device 50Y has a developing roll 52Y that exposes a part of the peripheral surface from an opening provided in the casing 51Y. Further, it also includes a first transport screw 53Y, a second transport screw 54Y, a developing doctor 55Y, a toner concentration sensor (hereinafter referred to as T sensor) 56Y, and the like.

  The casing 51Y contains a Y developer containing a magnetic carrier and a negatively chargeable Y toner. The Y developer is frictionally charged while being agitated and conveyed by the first conveying screw 53Y and the second conveying screw 54Y, and is then carried on the surface of the developing roll 52Y as a developer carrying member. Then, after the layer thickness is regulated by the developing doctor 55Y, the layer is conveyed to a developing area facing the photoreceptor 2Y, where Y toner is attached to the electrostatic latent image on the photoreceptor 2Y. This adhesion forms a Y toner image on the photoreceptor 2Y. The Y developer that has consumed Y toner by the development is returned to the casing 51Y as the surface of the developing roll 52Y (developing sleeve) rotates. On the other hand, the Y toner image contributing to the development is transferred to the transfer paper P conveyed by the paper conveyance belt 151. The developing roll 52Y has a developing sleeve made of a non-magnetic pipe that is driven to rotate by a driving means (not shown), and a magnet roller (not shown) that is included so as not to be rotated. The Y developer is attracted and carried on the surface of the developing sleeve by the magnetic force generated by the magnet roller.

  The T sensor 56Y made of a magnetic permeability sensor is attached to the bottom plate of the casing 51Y and outputs a voltage having a value corresponding to the magnetic permeability of the Y developer conveyed by the first conveying screw 53Y. Since the magnetic permeability of the developer shows a good correlation with the toner density of the developer, the T sensor 56Y outputs a voltage having a value corresponding to the Y toner density. The value of the output voltage is sent to a toner supply control unit (not shown). This toner replenishment control unit is provided with storage means such as a RAM and the like. In this, a Vtref for Y which is a target value of the output voltage from the T sensor 56Y and an output from a T sensor mounted on another developing device. Data on Vtref for M, C, and K, which is a target value of voltage, is stored. For the Y developing device 50Y, the value of the output voltage from the T sensor 56Y is compared with the Y Vtref, and a later-described Y suction pump 210Y is driven for a time corresponding to the comparison result. As a result, the toner is supplied into the developing device 50Y via the Y toner. By controlling the driving of the suction pump (toner replenishment control) in this way, an appropriate amount of Y toner is replenished to the Y developer whose Y toner density has been reduced with development, and the developer in the developing device 50Y. The Y toner density is maintained within a predetermined range. Similar toner replenishment control is performed for the other developing units. The suction pump 210Y is disposed directly above the developing device 50Y as shown in the figure, but is not a component of the toner image forming unit 100Y but a component of a Y toner conveying device to be described later. In the figure, the suction pump 210Y is indicated by a dotted line.

  Two paper feed cassettes 120 and 130 are disposed at the bottom of the printer body. These paper feed cassettes 120 and 130 store a plurality of transfer papers P in a stack of transfer papers, and press paper feed rollers 121 and 131 against the uppermost transfer paper P. Then, the sheet feeding rollers 121 and 131 are rotated at a predetermined timing to send the transfer sheet P to the sheet feeding path. A registration roller pair 140 is disposed at the end of the paper feed path, and the transferred transfer paper P is synchronized with the Y toner image formed on the photoreceptor 2Y of the Y toner image forming unit 100Y. At the timing of obtaining, the image is sent out to a transfer device 150 described later.

  FIG. 3 is an enlarged configuration diagram illustrating a main configuration of the transfer device 150. In the figure, the transfer device 150 has a belt device having a paper conveying belt 151 and a plurality of stretching rollers. Specifically, there are five stretching rollers mounted on the belt device: an entrance roller 152, a separation roller 153, a driving roller 154, a tension roller 155, and a lower roller 156. In addition to the belt device configured as described above, the transfer device 150 includes an electrostatic adsorption roller 157, four transfer bias rollers 158Y, M, C, and K, four transport support rollers 159Y, M, C, and K, a belt cleaning device 160, A pressing roller 161 and the like are included. It also has an inlet bracket 162, a swing bracket 163, an outlet bracket 164, a cam 165, and the like.

  The paper transport belt 151 is endlessly moved counterclockwise in the drawing by a driving roller 154 that is rotated counterclockwise in the drawing by a driving unit (not shown) while being stretched by a plurality of stretching rollers.

  The entrance roller 152, the transfer bias rollers 158Y to 158K, the conveyance support rollers 159Y to K, the separation roller 153, the driving roller 154, the tension roller 155, and the lower roller 156 are all in contact with the back surface of the paper conveyance belt 151. Among these rollers, the entrance roller 152 disposed on the rightmost side in the drawing is configured to sandwich the paper transport belt 151 between the entrance roller 152 and the electrostatic adsorption roller 157 disposed in the vicinity thereof. The electrostatic attraction roller 157 applies a charge to the front surface of the belt by an electrostatic attraction bias applied from a power source (not shown), thereby transferring the transfer paper P sent out from a pair of registration rollers (140) described later. Try to electrostatically attract.

  The four transfer bias rollers 158Y, 158, M, C, and K are rollers in which a metal core is covered with an elastic body such as a sponge, and are pressed toward the photoreceptors 2Y, 2M, 2C, and 2K, respectively. The paper conveying belt 151 is sandwiched. By this pressing, four transfer nips for Y, M, C, and K are formed in which the photoreceptors 2Y, M, C, and K and the paper transport belt 151 are in contact with each other with a predetermined length in the belt moving direction. The transfer bias rollers 158Y, 158, Y, M, C, and K are applied with a transfer bias that is controlled at a constant current by a transfer bias power source. As a result, transfer charges are applied to the back surface of the paper conveyance belt 151 via the transfer bias rollers 158Y, 158, M, C, and K, and between the paper conveyance belt 151 and the photoreceptors 2Y, M, C, and K at each transfer nip. A transfer electric field is formed. In this printer, the transfer bias rollers 158Y, 158, M, C, and K are provided as transfer means, but a brush, a blade, or the like may be used instead of the rollers. Also, a transfer charger or the like may be used.

  Of the four transfer bias rollers 158Y, M, C, and K, three for Y, M, and C are supported by the swing bracket 163 via bearing members (not shown). The swing bracket 163 is disposed inside the loop of the paper transport belt 151, and is configured to be swingable about the rotation shaft 162a. Of the four transport support rollers 159Y, M, C, and K, three for Y, M, and C are also supported by the swing bracket 163. Below the swing bracket 163 in the figure, there is disposed a cam 165 that is driven to rotate about a rotation shaft 165a by a drive means (not shown). When this rotation is stopped at the position where the cam surface abuts against the swing bracket 163, the swing bracket 163 is swung counterclockwise in the figure around the rotation shaft 163a. The transfer bias rollers 158Y, M, and C for Y, M, and C are brought into contact with the photoreceptors 2Y, M, and C via the paper conveyance belt 151, and transfer nips for Y, M, and C are formed. The On the other hand, when the cam 165 is stopped at a position where the cam surface does not hit the swing bracket 163, the swing bracket 163 is swung clockwise around the rotation shaft 163a. Then, the transfer bias rollers 158Y, M, and C for Y, M, and C move to a position where the paper transport belt 151 is not pressed against the photoreceptors 2Y, M, and C, and transfer nips for Y, M, and C are moved. Will not be formed. As described above, the transfer device 150 forms the transfer nips for Y, M, and C by bringing the paper transport belt 151 into contact with the photoreceptors 2Y, M, and C by swinging the swing bracket 163, or transporting the paper. The belt 151 is separated from the photoreceptors 2Y, M, and C.

  The entrance roller 152, the electrostatic adsorption roller 157, and the lower roller 156 are supported by the entrance bracket 162 via bearing members (not shown). The entrance bracket 162 is disposed inside the loop of the paper transport belt 151 and is configured to be swingable about the axis of the lower roller 156.

  The swing bracket 163 has a guide hole 163b in the vicinity of the left end in the figure, and a pin 162a extending from the inlet bracket 162 is movably positioned therein. When the cam 165 is rotated counterclockwise in the drawing, the pin 162a in the guide hole 162b is pushed up. Then, the inlet bracket 151 is linked to the swing of the swing bracket 163 and swung counterclockwise in the drawing around the axis of the lower roller 156, and the entrance roller 152, the electrostatic adsorption roller 157, and The lower roller 156 is pushed up. Further, when the swing bracket 163 is swung clockwise in the figure, the inlet bracket 151 is linked to it and swings clockwise in the figure, and the entrance roller 152, the electrostatic adsorption roller 157 and the lower roller 156 are moved. Move down. By the movement of the entrance roller 61, the electrostatic adsorption roller 157, and the lower roller 156 accompanying the swing of the swing bracket 163, the paper transport surface by the paper transport belt 151 is maintained in a straight line.

  When transferring the black monochrome toner image onto the transfer paper P, the transfer device 150 rotates the swing bracket 163 in the clockwise direction in the drawing to move the paper transport belt 151 to the Y, M, and C photoconductors 2Y. , M, C. When transferring a black monochrome toner image, the toner image is not transferred at the transfer nips for Y, M, and C. Therefore, the black monochrome toner image is transferred without forming these transfer nips. is there. As a result, it is possible to transfer a black monochromatic toner image without imposing an extra load on the paper transport belt 151 and its drive system.

  Of the four transfer bias rollers 158Y, M, C, and K, the K transfer bias roller 158K is supported by the outlet bracket 164 via a bearing member (not shown). The outlet bracket 164 is disposed inside the loop of the paper conveying belt 151 and is configured to be swingable about the axis of the outlet roller 165. Of the four transport support rollers 159Y, M, C, and K, the transport support roller 159K for K is also supported by the outlet bracket 164. The transfer bias roller 158K for K moves to a position where the paper transport belt 151 is not pressed against the photoconductor 2K for K by the clockwise swing of the exit bracket 164 in the drawing. In this state, when the swing bracket 163 swings clockwise in the drawing, the paper transport belt 151 is separated from all the photoreceptors 2Y, M, C, and K. The transfer device 150 can be attached to and detached from the printer main body in such a state that the paper transport belt 151 is separated from all the photoconductors.

  When transferring a full-color image, which will be described later, to the transfer paper P, the transfer device 150 brings the paper transport belt 151 into contact with all the photoreceptors 2Y, 2M, 2C, 2K, and is used for Y, M, C, and K. Form a transfer nip. The transfer paper P sent out from a registration roller pair (140), which will be described later, is sandwiched between the above-described electrostatic adsorption roller 157 and the paper transport belt 151. Then, the toner passes through the transfer nips for Y, M, C, and K sequentially while being attracted to the front surface of the paper transport belt 151. As a result, the Y, M, C, and K toner images on the photoconductors 2Y, 2M, 2C, and 2K are superimposed on the transfer paper P at the transfer nip, and the transfer paper is subjected to the effects of the transfer electric field and the nip pressure. The image is superimposed on P and transferred. A full-color image is formed on the transfer paper P by this superposition transfer.

  The transfer paper P on which the full-color image is formed approaches the belt stretching position by the separation roller 153 as the paper conveying belt 151 moves endlessly. At the belt stretching position, the separation roller 153 winds the paper transport belt 151 at a steep winding angle that substantially reverses the endless movement direction of the paper transport belt 151. The transfer paper P adsorbed on the paper transport belt 151 cannot follow such a sudden change in the moving direction of the belt and is separated from the paper transport belt 151. Then, it is delivered to a fixing device (not shown).

  The tension roller 155 applies a predetermined tension to the paper transport belt 151 by being biased toward the paper transport belt 151 by a spring. A pressing roller 161 is pressed against the front surface of the belt extension portion between the tension roller 155 and the driving roller 154. By this pressing, the paper conveying belt 151 is curved toward the inside of the loop. Since the paper conveyance belt 151 is greatly curved in this way, a larger portion of the paper conveyance belt 151 is wound around the driving roller 154. The belt cleaning device 160 is in contact with the front surface of the winding portion. Dirt toner transferred from each of the photoreceptors 2Y, 2M, 2C, and 2K adheres to the front surface of the paper transport belt 151 that has transferred the transfer paper P to the fixing device at the position where the separation roller 153 is stretched. ing. The belt cleaning device 160 is for removing the dirty toner from the paper transport belt 151.

  In FIG. 1 described above, the fixing device 170 includes a pressure roller 171, a fixing belt 172, a heating roller 173, a driving roller 174, and the like. The fixing belt 172 is endlessly moved clockwise in the drawing by a driving roller 174 that is rotated by a driving unit (not shown) while being stretched by a heating roller 172 and a driving roller 174. The heating roller 172 as a heating means includes a heat source such as a halogen lamp, and thereby heats the fixing belt 172 from the back surface. On the other hand, the pressure roller 171 as a contact roller rotates to move the surface in the same manner as the belt at the contact portion while contacting the fixing belt 172 moved endlessly. The transfer paper P delivered from the paper transport belt 151 of the transfer device 150 to the fixing device 170 is sandwiched between the fixing nips in such a posture that the image transfer surface is in contact with the fixing belt 172. Then, it passes through the fixing device 170 while the full-color image is fixed on the image transfer surface by heating or pressing.

  The transfer paper P that has passed through the fixing device 170 passes through a pair of transport rollers, a reversing guide plate, and the like, and then passes through the pair of transport rollers and is discharged toward a stack unit 180 provided on the upper surface of the printer housing.

  In FIG. 2 described above, the surface of the photoreceptor 2Y after passing through the transfer nip for Y is formed. In the drawing, a predetermined amount of lubricant is applied by the brush roller 3Y that is driven to rotate counterclockwise, and then cleaned by the counter blade 4Y. Then, the static electricity is removed by the light emitted from the static elimination lamp 5Y to prepare for the formation of the next electrostatic latent image.

  The discharge member 13Y of the charging roller 10Y is not in contact with the photoreceptor 2Y, but the toner on the photoreceptor 2Y may adhere due to electrostatic force. The adhered toner is cleaned from the surface of the discharge member 13Y by a roller cleaning device 20Y that rotates while contacting the discharge member 13Y.

  The process unit 1Y is supported by a common support so that the photosensitive member 2Y, the charging device, the brush roller 3Y, the counter blade 4Y, the charge removal lamp 5Y, and the like can be attached to and detached from the printer body as a single unit. It is a thing.

  Of the four toner image forming units 100Y, 100M, 100C, and 100K, the Y toner image forming unit 100Y has been described, but the other color toner image forming units 100M, 100C, and K have the same configuration. Therefore, explanation is omitted.

  As in this printer, a plurality of toner image forming units 100Y, 100M, 100C, and 100K corresponding to each color are arranged along the stretched surface of the belt such as the paper transport belt 151, and each color toner formed by these. A method of transferring an image by superimposing it on a transfer body is called a tandem method. As a method of forming a color image without using the tandem method, toner images of different colors are sequentially formed on the photoconductor in a toner image forming unit equipped with one photoconductor and a plurality of developing units. There is a method in which these are transferred onto the intermediate transfer member in sequence. In order to obtain a full-color image by this method, it is necessary to form toner images of four colors separately from each other, and it is difficult to perform high-speed image formation. In contrast, the tandem method is advantageous in increasing the image forming speed because four color toner images can be formed in parallel.

  In recent years, where the printing speed of color images is required to be increased, the tandem method is becoming mainstream. In the tandem system, a strict limit is often imposed on the layout in the apparatus for the purpose of space saving. For example, in this printer, as shown in FIG. 1, the paper conveyance belt 151 is stretched in an obliquely long posture, and the four toner image forming units 100Y, 100M, 100C, and 100K are attached to the paper conveyance belt 151. The device is downsized by arranging it diagonally along the slanting surface. In such a configuration, it becomes difficult to dispose a toner container containing replenishing toner near the toner image forming unit. In this case, a layout in which the toner container is disposed at a position relatively distant from the toner image forming unit must be employed, and a mechanism for transporting the toner for a long distance is required. As a mechanism for transporting toner, a screw tube having a screw disposed in a transport tube has been known for a long time, but this is not suitable for transporting toner for a long distance. In particular, if the transport direction is an upward gradient or the transport path is bent in a complicated manner, it becomes easy to clog toner in the transport pipe. On the other hand, in a suction-type toner transport device that sucks and transports toner in a transport pipe by a suction pump such as a Mono pump, the toner is reliably transported even on a transport path with an upward gradient or a bend due to the excellent suction force of the suction pump. be able to.

  Therefore, in this printer, as shown in FIG. 1, the four toner containers 260Y, M, C, and K are disposed at positions relatively distant from the four toner image forming units 100Y, 100M, 100K, and 100K, respectively. Thus, the layout restrictions are cleared, and a suction type toner conveying device for Y, M, C, and K is employed. In FIG. 1, four subscripts 260Y, M, C, and K are attached to one toner container. This is because the four toner containers are in a direction perpendicular to the paper surface in the figure. This is because only one outline of the toner container can be drawn because they are arranged side by side.

  FIG. 4 is a schematic configuration diagram illustrating one of the four toner transport devices for Y, M, C, and K. Since the four toner conveying devices have the same configuration except that different colors of toner are used, only one toner conveying device will be described below. For the toner conveying device, the subscripts Y, M, C, and K are omitted in the explanatory text and the drawings.

  The toner conveying device 200 includes a suction pump 210, a container holder 230, a toner container 260, an air supply unit 280, and the like. The suction pump 210 is of a type called a uniaxial eccentric screw pump or a Mono pump, and generates a negative pressure in the suction port 214 by rotating a rotor 212 in the stator 211 by a suction motor 213. The suction port 214 is connected to the distal end of a flexible transfer tube 220.

  The container holder 230 includes a holder portion 231 having an upper opening in the figure, a nozzle 235 inserted in the bottom surface thereof, and the like. The holder portion 231 is for holding the toner container 260. The toner container 260 serving as a powder container encloses toner in a bag portion 261 having a thickness of several tens to several hundreds [μm] made of a material such as paper, cardboard, or plastic that exhibits a certain degree of rigidity. . A cap 262 is fixed on the toner discharge side of the bag. The base portion 262 includes an engagement portion 263 made of a rigid material such as resin or paper so as to be engaged in the opening of the bag portion 261, and an opening seal portion 264 made of an elastic material such as sponge. ing. The toner container 260 having such a configuration is attached to the holder part 231 of the container holder 230 with the base part 262 side facing downward in the vertical direction. At this time, the tip of the nozzle 235 fixed to the bottom surface of the holder portion 231 passes through the opening seal portion 244 of the base portion 262 of the toner container 260 and enters the bag portion 261. Since the opening seal portion 264 is in close contact with the periphery of the nozzle 235, toner leakage from the toner container 260 to the outside is prevented. A toner suction port 236 is formed on the tip side of the nozzle 235. The rear end side is connected to the transport tube 220.

  The conveyance tube 220 connecting the suction pump 210 and the nozzle 235 is formed with an inner diameter of 3 to 7 [mm], and a rubber material or a plastic material excellent in flexibility and toner resistance is used. . Examples of the rubber material include polyurethane rubber, nitrile rubber, EPDM rubber, silicon rubber and the like. Examples of the plastic material include polyethylene and nylon. By using the flexible conveyance tube 51 with excellent flexibility, it is possible to freely arrange the toner transfer path inside the copying machine, and the layout flexibility inside the apparatus is very good.

  FIG. 5 is an exploded perspective view showing a pump portion of the suction pump 210. In the drawing, the pump portion (portion excluding the suction motor and the like) of the suction pump 210 has a stator 211, a rotor 212, a holder 215 containing these, and the like. The stator 211 has an internal thread shape in which a double pitch spiral groove is formed in an elastic member such as rubber. The rotor 212 is formed of a material such as metal or resin in the shape of an external thread, and is inserted into the spiral groove of the stator 211 so as to be rotatable. A rotary drive shaft 217 fixed by a spring pin 216 is connected to the rear end of the rotor 212. The holder 215 containing the stator 211 supports the stator 211 so as to be swingable in the direction of arrow A in the figure by bringing a flange portion provided at the end of the stator 211 into contact with the inner peripheral surface thereof. Due to this swing, a gap G is formed between the inner surface of the holder 215 and the outer surface of the stator 211. A suction motor (not shown) is connected to the tip of the rotation drive shaft 217, and the rotor 212 rotates in the stator 211 as this rotates. At this time, the rotor 212 rotates eccentrically due to its complicated shape. This is why the suction pump 210 is called a uniaxial eccentric screw pump. When the rotor 212 rotates eccentrically, the stator 211 swings in the direction of arrow A in the figure. When the rotor 212 rotates, the closed space formed in the stator 211 moves from the suction port 214 side to the rotation drive shaft 217 side, and a suction force P2 of 10 to 20 [kPa] is generated at the suction port 214. Then, the toner in the transport tube is sucked into the pump unit from the suction port 214. The sucked toner passes through the inside of the pump unit and is then discharged from a discharge port (not shown) provided on the lower side of the rotation drive shaft 217.

  A space from the inside of the bag portion 261 of the toner container 260 to the inside of the suction pump 210 via the inside of the nozzle 235 and the inside of the transport tube 220 is a sealed environment. For this reason, when the suction pump 210 is operated and a negative pressure is generated in the transport tube 220, a suction force is generated at the toner suction port 236 of the nozzle 235. The toner in the bag portion 261 is sucked from the toner suction port 236 and sequentially passes through the nozzle 235, the transport tube 220, and the suction pump 210, and is connected to the discharge side of the suction pump 210. The developer 50 is replenished.

  In this way, the toner conveying device 200 of the printer conveys the toner in the toner container 260 shown in FIG. 4 by the suction by the suction pump 210. In such a configuration, there is no need to provide a movable member such as a screw-shaped auger in the transport pipe for transporting the toner in the toner container 260 to the developing device 50. Therefore, it is possible to simplify the configuration and suppress an increase in cost. In addition, a deformable transport tube 220 can be freely discharged into the printer as the transport pipe. Thereby, the layout freedom degree of a conveyance path | route can be improved significantly.

  In addition, although the example using the MONO pump has been described as the suction pump 210, other types of pumps may be used as long as the pump generates a pressure lower than the atmospheric pressure and sucks toner by the pressure difference.

  FIG. 6 is a partial perspective view showing the vicinity of the center of the nozzle 235 in the longitudinal direction. In the figure, a nozzle 235 is made of a colored resin material such as black ABS, and a transparent tube 235c made of a transparent material such as PET (polyethylene terephthalate) or glass is fitted near the center in the longitudinal direction. . The nozzle 235 is provided with two window openings 235a and 235 facing each other with the transparent tube 235c and the toner flow path in the tube interposed therebetween. A transmissive optical sensor 250 is disposed outside the nozzle 235 so as to sandwich the transparent window forming portion of the nozzle 235. The transmissive optical sensor 250 includes a light emitting element 250a and a light receiving element 250b. Light emitted from the light emitting element 250a passes through the path of one window opening 235a of the nozzle 235 → one end portion in the cross-sectional direction of the transparent tube 235c → the inner toner flow path → the other window opening 235b. Is received. The light receiving element 250b outputs an amount of voltage corresponding to the amount of received light.

  As the amount of light received by the light receiving element 250b increases, the summer value of the output from the light receiving element 250b increases. On the other hand, the amount of light received by the light receiving element 250b decreases as the amount of toner flowing through the toner flow path in the tube of the nozzle 235 increases. Therefore, the larger the output voltage from the transmission type optical sensor 250 (light receiving element), the lower the toner flow rate in the nozzle 235 is. When the situation where the toner flow rate falls below the predetermined amount continues, the remaining amount of toner in the toner container 260 is nearly empty. A toner replenishment control unit (not shown) uses this phenomenon to monitor a phenomenon in which the output voltage from the transmission optical sensor 250 exceeds a predetermined threshold value. It is determined that the toner in the container 260 has run out. Then, the container replacement request is notified to the user.

  In the example shown in the figure, the nozzle 235 is provided with two window openings 235a and 235b, and a transparent tube 235c is fitted into this portion to form a light transmission portion. However, the entire nozzle 235 is made of a transparent material. May be. Further, if only one window opening is provided and the inner wall of the nozzle is mirror-finished so that light incident on the toner flow path in the tube through the transparent tube is reflected by the nozzle inner wall, a reflective optical sensor Can also be used.

  In this printer having the above basic configuration, the four toner image forming units 100Y, 100M, 100K, the optical writing unit 110, the transfer device 150, the main control unit for controlling these, and the like are used as recording members. Image forming means for forming an image by attaching toner as powder to the transfer paper P is configured.

Next, a characteristic configuration of the printer will be described.
In the electrophotographic system and the direct recording system, toner is charged and used for image formation, and therefore, a toner that is easily charged is used. Since a certain amount of pressure is applied to the toner in the nozzle 235 of the toner conveying device 200, the toner is easily charged. When the toner charged in the nozzle 235 comes into contact with the inner wall of the transparent tube 235c made of glass or resin, the transparent tube 235 may generate a mirror image force due to polarization and adhere well to the inner wall. If further pressure is applied in this state, the toner eventually adheres to the transparent tube 235 and becomes contaminated with toner. When such toner contamination occurs, the amount of light transmitted by the transmissive optical sensor 250 is reduced regardless of the toner flow rate in the in-pipe toner flow path of the nozzle 235. Therefore, an error such as “the toner flow rate is still sufficiently high”. Detection occurs. As a result, the toner end in the toner container 260 cannot be accurately detected. Therefore, in this printer, the inner wall of the transparent tube 235 is periodically cleaned in order to suppress toner sticking to the inner wall of the transparent tube 235.

  In FIG. 4 described above, an air supply unit 280 serving as an in-pipe air supply unit is connected to the nozzle 235 serving as the transfer tube 235. The air supply unit 280 includes an air pump 281 that blows air from the air supply port 281a by a known technique, a flexible air supply tube 282 that connects the air supply port 281a and the nozzle 235, and the like.

  FIG. 7 is an enlarged configuration diagram showing the nozzle 235 in an enlarged manner. The nozzle 235 as a whole is shaped like a Japanese hiragana “shi” character, and the upper end of the “shi” character is the tip. As described above, the toner suction hole 236 for receiving the toner in the toner container into the nozzle 235 is formed at the tip of the nozzle 235. Further, the transparent tube 235c described above is fitted in the vicinity of the center of the nozzle 235 in the longitudinal direction, and two window openings 235a and 235b are formed on the nozzle outer walls on both sides thereof. In the longitudinal direction of the nozzle 235, a portion closer to the nozzle rear end side (conveyance destination side) than the transparent tube 235c constituting a part of the transmitted light portion includes an inner tube 235e and an outer tube 235d containing the inner tube 235e. It is a double-structured tube. At the place of the double structure tube, an air supply / reception port 235f as an opening is formed in the outer tube 235d. The air supply inlet 235f is connected to an air supply tube 282 that is an air supply tube of the air supply section (280). At a location closer to the nozzle rear end side (conveyance destination side) than the air supply / reception port 235f, the gap between the inner tube 235e and the outer tube 235d is blocked over the entire circumference in the tube circumferential direction.

  The air blown out from the air pump 281 enters the gap between the inner tube 235e and the outer tube 235d in the double structure tube of the nozzle 235 via the air supply tube 282. As described above, since this gap is closed on the nozzle rear end side, the air that has entered the gap, as indicated by the arrows in the figure, moves toward the nozzle tip side with the inner tube 235e and the outer tube 235d. Exit the gap.

  Although a detailed control flow will be described later, air supply by the air pump 281 is performed when the suction pump 210 is not operating. Since the air that has exited the gap between the inner tube 235e and the outer tube 235d cannot advance to the rear end side of the nozzle 235 that is a sealed space because the suction pump 210 is stopped, the air goes directly to the nozzle tip side. . Then, while rubbing the inner wall of the transparent tube 235c located immediately above the double structure tube, the toner powder moves toward the nozzle tip like a bubble moving in water. At this time, the inner wall is cleaned by blowing off toner adhering to the inner wall of the transparent tube 235c from the inner wall. The air that has moved to the tip of the nozzle exits the nozzle 235 from the toner suction hole 236 and enters the toner container.

  FIG. 8 is a perspective view showing the toner container 260. As shown in the figure, a ventilation filter 263 is provided at the bottom of the bag portion 261 of the toner container 260 (on the side opposite to the toner discharge side). The air sent from the air pump (281) to the bag portion 261 via the air supply tube (282) and the nozzle (235) finally passes through the ventilation filter 263 and is then discharged from the container. Discharged. The mesh of the ventilation filter 263 is thin enough to prevent the toner particles from passing therethrough.

  As shown in FIG. 9 and FIG. 10, the transparent tube 235c has a structure in which the inner diameter is reduced from the nozzle rear end side which is the toner transport destination side toward the nozzle front end side which is the powder container side. It is used. In such a configuration, the double-structured tube located on the nozzle rear end side of the transparent tube 235c is blown from the gap between the inner tube 235e and the outer tube 235d toward the nozzle tip side along the inner wall of the outer tube 235d. Air is reliably blown onto the inner wall of the transparent tube 235c that is tapered in the air moving direction. Thereby, the inner wall of the transparent tube 235c can be efficiently air-cleaned.

  FIG. 11 is a block diagram showing a part of the electric circuit of the printer. In the figure, the toner replenishment control unit 300 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like. The toner replenishment control unit 300 includes an optical writing control circuit 301 and the above-described Y, M, C, and K T sensors 56Y, M, C, and K that detect the toner density of the two-component developer in the developing unit. Etc. are connected. Also, suction motors 213Y, M, C, K, air pumps 281Y, M, C, K, transmission optical sensors 250Y, M, C provided in the toner transport device (200) for Y, M, C, K. , K, etc. are also connected.

  The optical writing control circuit 301 is a circuit for controlling the optical writing unit 110 described above based on image information sent from a personal computer or the like.

  The toner replenishment control unit 300 stores the output voltage values from the T sensors 56Y, 56M, 56C, and K and the RAM. The toner replenishment operation time (drive amount) by the suction motors 213Y, M, C, and K is determined based on the comparison with the Y, M, C, and K Vtref.

  Specifically, first, the excess / deficiency operation time Ta based on the excess / deficiency of the toner density at the present time is calculated by an arithmetic expression of “over / shortage operation time Ta = (Vtref−T sensor output voltage value) × coefficient K1”. calculate. In this arithmetic expression, the coefficient K1 is a coefficient for converting the difference between Vtref and the T sensor output voltage value into the suction pump operation time necessary for supplying the corresponding amount of toner. When the toner density of the two-component developer in the developing device (50) exceeds the reference density, the excess / deficiency operation time Ta becomes a negative value.

  Next, the toner supply control unit 300 calculates the image area of the printout image based on the image information sent from the optical writing control circuit 301. Then, the consumption-scheduled operation time Tb is calculated by an arithmetic expression “consumption-scheduled operation time Tb = image area × coefficient K2”. In this arithmetic expression, the coefficient K2 is a coefficient for converting the toner consumption corresponding to the image area into the suction pump operating time necessary for the replenishment thereof. The toner replenishment control unit 300 sets the sum of the calculated excess / deficiency operation time Ta and the consumption scheduled operation time Tb as the toner replenishment operation time, and drives the suction motor for that time. Such suction motor drive control is performed for each of the colors Y, M, C, and K.

  FIG. 12 is a flowchart illustrating a flow of toner supply control by the toner supply control unit 300 serving as a conveyance control unit. The toner replenishment control unit 300 stands by until a print start command is issued (step 1, hereinafter “step” is referred to as S). When the print start command is issued (Y in S1), the air pump for each color is set to a predetermined value. It is driven for a time (S2), and the transparent window in each color nozzle is air-cleaned. When the air cleaning is finished (Y in S3), after reading the T sensor output voltage value of each color (S4), the operation time Ta for excess / deficiency of each color is calculated based on the read value and Vtref (S5). Then, the image area of each color is calculated, and based on the calculation result, the consumption scheduled operation time Tb of each color is calculated (S6). Next, after calculating the toner replenishment operation time Tc, which is the sum of the excess / deficiency operation time Ta and the consumption scheduled operation time Tb, for each color (S7), the respective toner supply motor operation times Tc corresponding to the respective suction motors are calculated. And the toner is supplied to the developing device (S8). At the same time, toner end determination processing is performed for each color toner container (S9). In this toner end determination process, for each color, the output voltage value from the transmission optical sensor is converted into light transmittance while sampling 40 times at intervals of 20 [ms]. Then, when the light transmittance of 80 [%] or more continues six times or more, it is determined as the toner end. If a toner end has occurred (Y in S10), after notifying the user that the toner container of the corresponding color is a toner end by displaying on a display unit (not shown) or the like (S11), the printing operation is performed. The program is forcibly interrupted (S12). On the other hand, if the toner end has not occurred (N in S10), the presence / absence of the next print start command is determined (S13), and if there is, the control flow is looped to S2. If not, the series of control flow is terminated.

  In such toner replenishment control, prior to the toner end determination process, that is, prior to the calculation of the remaining amount of toner in the toner container, the air pump of the air supply unit 280 is driven for a predetermined time, and the inner wall of the transparent tube Air cleaning. As a result, the toner flow rate can be detected by the transmissive optical sensor immediately after air cleaning, and the toner flow rate detection control can be enhanced.

  The example in which four air pumps 281Y, M, C, and K are provided corresponding to each color has been described, but each color may be supplied by one unit. In this case, a four-branch joint having four branch paths may be connected to the air supply port of the air pump, and each branch path may be connected to a corresponding color nozzle.

  FIG. 13 is an enlarged configuration diagram illustrating the nozzle 235 in the modified apparatus of the printer. In this modified apparatus, the tip side of the nozzle is a double-structure tube, and the tip is composed only of the inner tube 235e. The double structure tube is formed at a location closer to the nozzle tip side (toner container side) than the transparent tube 235c constituting the light transmission portion. A first air supply / reception port 235f as an opening is formed in the vicinity of the end of the outer tube 235d of the double structure tube on the conveyance destination side. Further, a second air supply / receiving port 235h as a second opening is formed at a location closer to the nozzle tip side (toner container side) than the first air supply / receiving port 235f in the outer tube 235d of the double structure tube. Has been. Between the first air inlet / outlet 235f and the second air inlet / inlet 235h, a gap between the inner pipe 235e and the outer pipe 235d is formed in the pipe circumferential direction by a sealing material 235g made of rubber packing or resin caulking material. It is blocked all around. The transparent tube 235c is located immediately below the double structure tube.

  One end side of the cleaning air supply tube 285 is connected to the first air supply / reception port 235f provided in the outer tube 235d, and the other end side of the cleaning air supply tube 285 is connected to the cleaning electromagnetic valve 284. Has been. Further, a stirring air supply tube 287 is connected to the second air supply inlet 235h provided in the outer tube 235d, and the other end side of the stirring air supply tube 287 is connected to the stirring electromagnetic valve 286. Has been. Although only the peripheral configuration of the toner container for one color is shown in the drawing, the toner container for four colors is provided in this printer. Accordingly, there are four toner containers 260, nozzles 235, cleaning air supply tubes 285, cleaning electromagnetic valves 284, stirring air supply tubes 287, and stirring electromagnetic valves 286, respectively.

  On the other hand, the air supply tube 282 extending from the air pump 281 is connected to the 8-branch joint 283. The eight-branch joint 283 branches the input-side flow path into eight on the output side. The eight branch paths are connected to a cleaning electromagnetic valve 284 for Y, M, C, and K, and a stirring electromagnetic valve 286 for Y, M, C, and K. In FIG. Only the cleaning solenoid valve 284 and one agitation solenoid valve 286 are shown.

  The air blown out from the air pump 281 is divided into eight via the air supply tube 282 and the eight branch joint 283, and then flows toward one of the eight electromagnetic valves. When the cleaning electromagnetic valve 284 is opened, the air passes through the cleaning air supply tube 285, and then enters the gap between the outer tube 235d and the inner tube 235e through the first air supply port 235f of the nozzle 235. To do. Since the above-mentioned gap is blocked by the sealing material 235g on the nozzle front side from the place where air enters, the air moves in the gap toward the nozzle rear end side. And when it leaves the gap, it moves along the inner wall of the transparent tube 235c just below the double structure tube for a while. Thereby, the inner wall of the transparent tube 235c is air-cleaned. However, since the rear end side of the nozzle toward the suction pump 210 is a sealed space, as shown by the arrows in the figure, the air eventually changes its direction toward the nozzle front side that is an open space. Then, the toner advances to the inside of the inner tube 235e while stirring the toner, and comes out of the nozzle from the toner suction port 236.

  On the other hand, when the agitation electromagnetic valve 286 is opened, the air in the eight-branch joint 283 passes through the agitation electromagnetic valve 286 and the agitation air supply tube 287, and then the second air supply inlet 235h of the nozzle 235. Passes through the gap between the outer tube 235d and the inner tube 235e. Since the gap is closed by the sealing material 235g on the nozzle rear end side from the place where the air has entered, the air moves in the gap toward the nozzle tip side. Then, the toner exits from the gap and enters the toner container 260, and the air present around the tip of the nozzle 235 is agitated with air. Thereby, toner aggregation around the nozzle 235 is suppressed.

  The air cleaning of the transparent window 235c and the stirring of the toner around the nozzles in the toner container 260 may be performed at the same time, but are more preferably performed at different timings. This is for the reason explained below. That is, as described above, the air cleaning of the transparent window 235c is preferably performed immediately before the toner supply by driving the suction pump 281 and the toner end determination process. On the other hand, since the toner density around the nozzle increases with the toner replenishing operation, it is desirable that the stirring of the toner around the nozzle is performed immediately after the toner replenishment. In view of this, in the present modification device, an electromagnetic valve is provided in each of the above-described branch paths that are a plurality of branch pipes. For each color, air cleaning of the transparent window 235c is performed prior to toner replenishment and toner end determination processing, while air agitation around the nozzle is performed after toner replenishment and toner end determination processing. Yes.

  In this modified apparatus, as the transparent tube 235c, as shown in FIG. 14 and FIG. 15, a structure having a smaller inner diameter from the nozzle front end side toward the nozzle rear end side is used. The direction of the taper is opposite to that of the transparent tube used in the configuration shown. This is because, in the configuration shown in FIG. 7, air flows in the transparent tube 235c from the nozzle rear end side toward the front end side, whereas in this modified apparatus, it moves from the nozzle front end side toward the rear end side. Because it flows. By tapering the inside of the transparent tube 235c in the direction in which air flows, it becomes possible to blow air on the inner wall of the transparent tube 235c with certainty.

  As the toner, it is desirable to use a toner produced by a polymerization method capable of achieving both good circularity and small particle size. This is because by using such a toner, a high-quality image can be obtained even with a printout having a very high resolution. However, on the other hand, the toner formed by the polymerization method has a smooth surface shape and a small particle diameter, so that the toner is easily contact-charged, so that it easily adheres to the inner wall of the transparent tube 235c. The present invention suppresses toner contamination on the inner wall of the transparent tube 235c, which is particularly likely to occur when using a polymerized toner capable of realizing high image quality, and achieves high image quality and high accuracy of toner end determination. Can do. Therefore, in the printer and the modified apparatus, the user is designated to use a polymerized toner manufactured by a polymerization method as the toner. As a method of specifying to the user, for example, the polymerized toner is packed and shipped together with the printer main body. Further, for example, the product number or product name of the polymerized toner may be specified in the printer main body or the instruction manual. Further, for example, it may be performed by notifying the user of the product number, product name, etc. in writing or electronic data. Alternatively, for example, the toner container 260 containing the polymerized toner can be shipped in a state of being set in the printer main body. All of these methods are employed in the present printer and the modified apparatus, but at least one of the methods is sufficient.

For reference, a method for producing a polymerized toner will be briefly described.
(1) Preparation of toner composition In an organic solvent such as ethyl acetate, a toner raw material composed of a resin, a colorant, a wax, a charge control agent, and a polyester resin (prepolymer) having an isocyanate group is dissolved, and the toner composition is dissolved in the toner composition. It was. The prepolymer is a polymer having two or more reactive groups in one base polymer molecule.
(2) Emulsification The toner composition and amines are added to an aqueous medium containing a surfactant, a viscosity modifier, and resin fine particles, and dispersed by shearing force to form an emulsified state.
(3) Aging In order to accelerate the elongation and crosslinking reaction due to the reaction between an isocyanate group and amines, the reaction system is heated.
(4) Desolvation As an example, a method of gradually raising the temperature of the entire system and evaporating and removing the organic solvent in the droplets can be employed.
(5) Alkali washing and water washing These are steps for removing foreign matters (surfactant, viscosity modifier, etc.) remaining on the surface of the obtained toner particles.
(6) Drying The obtained toner particles are collected by filtration and dried.
(7) External additive treatment If necessary, external additive fine particles (silica, titania, alumina, etc.) are externally added by a 0.1 to 5.0 part by weight mixer.

  So far, a two-component developing type copying machine using a two-component developer containing a toner and a magnetic carrier has been described. However, the present invention is also applied to a one-component developing method using a one-component developer not containing a magnetic carrier. Is possible. The present invention can also be applied to an image forming apparatus that transports a magnetic carrier or a two-component developer instead of transporting toner as powder. Further, the image forming apparatus is not limited to a copying machine, and may be another image forming apparatus such as a printer or a facsimile. In addition, a method of forming an electrostatic latent image by exposure using an LED or ion application may be used instead of the method of performing exposure using a laser beam. The present invention can also be applied to an image forming apparatus that forms a toner image by a direct recording method instead of an electrophotographic method.

  As described above, in the printer according to the embodiment, the location closer to the transport destination side (nozzle rear end side) than the transparent tube 235c (part of the light transmission portion) in the length direction of the nozzle 235 serving as the transport tube is the inner tube. A double-structured tube including 235e and an outer tube 235d containing the same is formed. Then, an air supply tube 282 that is an air supply tube of an air supply unit 280 that is an in-pipe air supply means is connected to an air supply and reception port 235f that is an opening provided in the outer tube 235d, and more than the air supply and reception port 235f in the double structure tube. The gap between the inner tube 235e and the outer tube 235d is closed over the entire circumference in the tube circumferential direction at a location approaching the conveyance destination side (nozzle rear end side). In such a configuration, as shown in FIG. 7, after the air sent into the nozzle 235 is applied to the inner tube 235e, the direction is changed toward the inner wall of the transparent tube 235c. Thereby, the air sent into the nozzle 235 can be intensively blown to the inner wall of the transparent tube 235c, and the cleaning effect can be improved.

  In the printer according to the embodiment, the transparent tube 235c serving as a light transmitting portion has a structure in which the inner diameter is reduced from the conveyance destination side (nozzle rear end side) toward the toner container side (nozzle front end side). Therefore, for the reason described above, the air sent into the nozzle 235 can be reliably blown to the inner wall of the transparent tube 235c.

  Further, in the modified apparatus, as shown in FIG. 13, the inner tube 235e and the inner tube 235e are included in the portion closer to the toner container side (nozzle tip side) than the transparent tube 235c in the length direction of the nozzle 235. The outer tube 235d is a double structure tube. Then, a cleaning air supply tube 285 serving as an air supply tube is connected to a first air supply / receiving port 235f provided in the outer tube 235d so as to be closer to the toner container than the first air supply / receiving port 235f in the double structure tube. The gap between the inner tube 235e and the outer tube 235d is blocked over the entire circumference in the tube circumferential direction at the approached point. Even in such a configuration, after the air sent into the nozzle 235 is applied to the inner tube 235e, the direction is changed toward the inner wall of the transparent tube 235c. Thereby, the air sent into the nozzle 235 can be intensively blown to the inner wall of the transparent tube 235c, and the cleaning effect can be improved.

  In the modified apparatus, a second air supply / reception port 235h that is a second opening is provided at a location closer to the toner container side than the first air supply / reception port 235d in the outer tube 235d. The gap between the inner tube 235e and the outer tube 235d is blocked over the entire circumference in the tube circumferential direction at a position between the first air supply / reception port 235f and the second air supply / reception port 235h. Further, one of a plurality of branch paths obtained by branching the air supply tube 282 into a plurality is connected to the first air supply receiving port 235f, and the other one is connected to the second air supply receiving port 235h. Yes. In such a configuration, as shown in FIG. 13, the air feeding means for stirring the toner around the nozzle and the air feeding means for air cleaning can be shared by a single air pump 281.

  In the modified apparatus, the transparent tube 235c, which is a part of the light transmitting portion, has a structure in which the inner diameter is reduced from the toner container side toward the transport destination side. Even in such a configuration, the air sent into the nozzle 235 can be reliably blown onto the inner wall of the transparent tube 235c for the reasons described above.

  Further, in the modified apparatus, an electromagnetic valve is provided in each of the eight branch passages as the plurality of branch pipes. For the reasons described above, for the toner stirring around the nozzle and for the air cleaning of the transparent pipe 235c. Thus, even if one air pump is also used, it is possible to perform air blowing for stirring the toner and air blowing for air cleaning at different timings. Thereby, each can be performed individually at the appropriate timing as described above, and efficient toner stirring and air cleaning can be performed.

  Further, in the printer and the modification apparatus according to the embodiment, the toner replenishment control as the conveyance control unit is made to calculate the remaining amount of toner in the toner container 260 based on the detection result by the transmissive optical sensor 250 as the optical sensor. Since the unit 300 is configured, an increase in cost due to the provision of the remaining toner sensor in the disposable toner container 260 can be avoided.

  Further, in the printer and the modification apparatus according to the embodiment, the toner replenishment control is performed so that the air pump 281 is driven for a predetermined time before the toner end determination process that is a calculation process of the remaining amount of toner. Since the portion 300 is configured, the transparent tube 235c is air-cleaned immediately before the transmission type optical sensor 250 detects the toner flow path in the nozzle 235, and the toner end determination accuracy (toner remaining amount detection accuracy) is improved. Can be increased.

1 is a schematic configuration diagram illustrating a printer according to an embodiment. FIG. 3 is an enlarged configuration diagram illustrating a toner image forming unit for Y in the printer together with a part of a transfer device. FIG. 3 is an enlarged configuration diagram illustrating a main configuration of the transfer device. FIG. 2 is a schematic configuration diagram illustrating one of four toner conveying devices in the printer. FIG. 3 is an exploded perspective view showing a pump portion of a suction pump of the toner conveying device. FIG. 6 is a partial perspective view showing the vicinity of the center in the longitudinal direction of the nozzle of the toner conveying device. The enlarged block diagram which expands and shows the same nozzle. FIG. 3 is a perspective view showing a toner container of the toner conveying device. The perspective view which shows an example of the transparent tube of the nozzle. The perspective view which shows another example of the transparent tube. FIG. 2 is a block diagram showing a part of an electric circuit of the printer. 6 is a flowchart illustrating a flow of toner supply control performed by a toner supply control unit of the printer. FIG. 5 is an enlarged configuration diagram illustrating nozzles in a modified apparatus of the printer. FIG. 10 is a perspective view showing an example of a transparent tube in the toner conveying device of the modified example device. The perspective view which shows another example of the transparent tube.

Explanation of symbols

50: Developer (conveyance destination)
100Y, M, C, K: Toner image forming unit (part of image forming means)
110: Optical writing unit (part of image forming means)
150: Transfer device (part of image forming means)
200: Toner conveying device 210: Suction pump (moving force applying means)
220: Conveying tube (conveying tube)
235: Nozzle (conveying pipe)
235a, b: Opening for window (part of light transmission part)
235c: Transparent tube (part of the light transmission part)
235d: Outer tube 235e: Inner tube 235f: Air inlet / outlet (opening)
235h: Second air inlet / outlet (second opening)
250: Transmission type optical sensor 260: Toner container (powder container)
280: Air supply part (in-pipe air supply means)
282: Air supply tube (air supply tube)
284: Solenoid valve for cleaning 285: Air supply tube for cleaning (air supply tube, branch tube)
286: Solenoid valve for stirring 287: Air supply tube for stirring (air supply tube, branch tube)
300: Toner replenishment control unit (conveyance control means)

Claims (9)

A powder container for storing powder, a transport pipe for receiving and discharging the powder discharged from the powder container to the transport destination, and at least a part of the transport pipe in the length direction are provided. An optical sensor for detecting the amount of light transmitted from one end side to the other end side in the cross-sectional direction of the transport tube with respect to the light transmissive portion, and the powder in the transport tube And a moving force applying means for applying a moving force from the powder container side toward the transport destination side, and the powder for transporting the powder in the powder container to the transport destination through the transport pipe In the body transport device,
A powder conveying apparatus comprising an in-pipe air feeding means for feeding air toward an inner wall of the light transmission part of the conveying pipe. In the powder conveying apparatus according to claim 1,
A location closer to the transport destination side than the light transmission part in the length direction of the transport tube is a double-structure tube including an inner tube and an outer tube containing the inner tube, and is provided in the outer tube. An air supply pipe of the in-pipe air supply means is connected to the opened opening, and a gap between the inner pipe and the outer pipe is formed at a location closer to the transport destination side than the opening of the double structure pipe. A powder conveying device characterized by being blocked over the entire circumference. In the powder conveying apparatus according to claim 2,
A powder conveying apparatus having a structure in which an inner diameter is reduced from the conveying destination side toward the powder container side as the light transmitting portion. In the powder conveying apparatus according to claim 1,
A place closer to the powder container side than the light transmission part in the length direction of the transport pipe is a double-structure pipe including an inner pipe and an outer pipe containing the inner pipe, and the outer pipe An air supply pipe of the internal air supply means is connected to the opening provided in the pipe, and the inner pipe and the outer pipe are connected at a location closer to the powder container side than the opening in the double structure pipe. A powder conveying device characterized in that the gap is closed over the entire circumference in the tube circumferential direction. In the powder conveying apparatus of Claim 4,
A second opening is provided at a position closer to the powder container side than the opening in the outer pipe, and the gap is extended over the entire circumference in the pipe circumferential direction at a position between the opening and the second opening. A powder conveying system characterized by closing and connecting one of a plurality of branch pipes obtained by branching the air supply pipe into a plurality of openings, and connecting the other one to the second openings. apparatus. In the powder conveying apparatus according to claim 4 or 5,
A powder conveying apparatus having a structure in which an inner diameter is reduced from the powder container side toward the conveying destination side as the light transmitting portion. In the powder conveying apparatus according to claim 5 or 6,
A powder conveying apparatus, wherein an electromagnetic valve is provided in each of the plurality of branch pipes. Image forming means for forming an image by attaching toner as powder to a recording member, a toner conveying device for conveying toner contained in a powder container to the image forming means, and conveyance control for controlling the toner conveying device An image forming apparatus comprising:
The powder conveyance device according to any one of claims 1 to 7 is used as the toner conveyance device, and the conveyance control is performed so that the remaining amount of toner in the powder container is calculated based on a detection result by the optical sensor. An image forming apparatus comprising a means. The image forming apparatus according to claim 8.
An image forming apparatus comprising: the conveyance control unit configured to perform control for driving the in-pipe air supply unit for a predetermined time prior to the calculation of the remaining amount of toner.

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