JP2013134313A - Powder conveying device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder conveyance device able to detect the status of conveyance of powder accurately.SOLUTION: The powder conveying device comprises: a conveyance pipe 102; an auger 104 for conveying powder in the conveyance pipe 102; a temperature adjustor 112 for causing and maintaining a predetermined temperature difference between the powder and the conveyance pipe 102; a heat flow flux detection sensor 114 for detecting a heat flow flux generated by the temperature difference; and a determination block 116 that determines the status of the conveyance of powder in the conveyance pipe 102 on the basis of the heat flow flux detected by the heat flow flux detection sensor 114.

Description

  The present invention relates to a powder conveying apparatus and an image forming apparatus.

  In Patent Document 1, as shown in FIGS. 2 and 5, a transmissive photosensor (76) is provided on a transparent window (74a, 74b) provided on an opposing wall of a powder conveyance tube, and the light emitting element (76a) is used. A technique is described in which emitted light is received by a light receiving element (76b) and the flow rate of powder is detected from the amount of received light. However, with this technique, it is determined that the flow rate of the powder is so large that the light received by the light emitting element (76a) decreases, and therefore, the state where the powder is clogged cannot be detected. In addition, when there is a conveying means inside the powder conveying tube, the powder flow rate cannot be detected by the transmission type photosensor (76).

  In Patent Document 2, as shown in FIG. 1, the toner bottle (3), which is a powder replenishment unit, is provided with a piezoelectric sensor (37) for measuring the weight thereof, and the flow rate of the powder is detected by measuring the weight. The technology to do is described. However, with this technique, it is not possible to detect the state of powder transport at an arbitrary location on the transport tube.

JP 2004-4394 A JP-A-2005-316034

  An object of this invention is to provide the powder conveying apparatus which enabled it to detect the conveyance state of powder exactly.

  According to a first aspect of the present invention, there is provided a powder conveying device comprising: a conveying pipe; conveying means for conveying powder inside the conveying pipe; and a temperature difference determined in advance between the powder and the conveying pipe. A temperature difference generating / maintaining means for generating and maintaining, a heat flux detecting sensor for detecting a heat flux generated by the temperature difference, and the powder in the inside of the transport pipe based on the heat flux detected by the heat flux detecting sensor. Determining means for determining the state of conveyance of the body.

  According to a second aspect of the present invention, there is provided a powder conveying apparatus comprising: a conveying pipe; a conveying means for conveying the powder inside the conveying pipe; and a power supply. The powder and the conveying pipe are preliminarily supplied to the powder conveying apparatus. A temperature difference generating / maintaining means for generating and maintaining a predetermined temperature difference; a power detection sensor for detecting power consumed by the temperature difference generation / maintaining means; and the transport pipe based on the power detected by the power detection sensor Determining means for determining the state of conveyance of the powder inside.

  The powder conveyance device according to claim 3 of the present invention is the powder conveyance device according to claim 1, wherein the determination means has a heat flux detected by the heat flux detection sensor within a predetermined range. In this case, it is determined that the state of conveyance of the powder inside the conveyance tube is a state where the powder is clogged inside the conveyance tube, and a command for eliminating the state where the powder is clogged is issued. It is characterized by emanating.

  The powder conveyance device according to claim 4 of the present invention is the powder conveyance device according to claim 2, wherein the determination means is configured such that the power detected by the power detection sensor is within a predetermined range. Determining that the state of transport of the powder inside the transport tube is a state where the powder is clogged inside the transport tube, and issuing a command for eliminating the state of clogging the powder It is characterized by.

  The powder conveyance device according to claim 5 of the present invention is the powder conveyance device according to claim 3 or claim 4, wherein the determination means is a command for eliminating the state where the powder is clogged. A command for increasing the operating speed of the conveying means or a command for reversing the operating direction of the conveying means is issued.

  An image forming apparatus according to a sixth aspect of the present invention includes an image carrier on which an electrostatic latent image is formed, a developing device that develops the electrostatic latent image formed on the image carrier with powder, and the developing device. 6. A transfer device that transfers the powder image developed by the above to a recording medium, and the powder that has not been transferred by the transfer device among the powder supplied from the developing device is conveyed. And a powder conveyance device according to the item.

  According to the powder conveying apparatus of the first aspect of the present invention, the powder is compared with the case where the powder conveying state in the conveying pipe is not determined based on the heat flux detected by the heat flux detecting sensor. Can be accurately detected.

  According to the powder conveyance device of the second aspect of the present invention, compared to the case where the powder conveyance state in the conveyance tube is not determined based on the electric power detected by the electric power detection sensor, the powder conveyance device is used. The state can be accurately detected.

  According to the powder conveyance device of the third aspect of the present invention, the state in which the powder is clogged in the inside of the conveyance pipe as compared with the case where the command for eliminating the state in which the powder is clogged is not issued. Can be eliminated.

  According to the powder conveying apparatus of the fourth aspect of the present invention, the state in which the powder is clogged in the inside of the conveying pipe as compared with the case where the command for eliminating the state in which the powder is clogged is not issued. Can be eliminated.

  According to the powder conveying apparatus of claim 5 of the present invention, compared with the case where the command for increasing the operating speed of the conveying means or the command for reversing the operating direction of the conveying means is not issued, the powder conveying device is arranged inside the conveying pipe. The state where the body is clogged can be easily eliminated.

  According to the image forming apparatus of the sixth aspect of the present invention, it is possible to provide an image forming apparatus provided with a powder conveying apparatus capable of accurately detecting a powder conveying state.

1 is a diagram illustrating a configuration of an image forming apparatus according to the present invention. FIG. 2 is a diagram illustrating a configuration around a photoconductor of FIG. 1. It is a figure which shows the structure of the powder conveying apparatus of 1st Embodiment which concerns on this invention. FIG. 4 is a diagram illustrating a relationship between a toner conveyance state inside the conveyance tube of FIG. 3 and an output value M of a heat flux detection sensor. FIG. 4 is a diagram illustrating a relationship between a toner conveyance state inside the conveyance tube of FIG. 3 and an output value M of a heat flux detection sensor. FIG. 4 is a diagram illustrating a relationship between a toner conveyance state inside the conveyance tube of FIG. 3 and an output value M of a heat flux detection sensor. FIG. 4 is a diagram illustrating a relationship between a toner conveyance state inside the conveyance tube of FIG. 3 and an output value M of a heat flux detection sensor. FIG. 2 is a diagram illustrating a time course of an output value M of a heat flux detection sensor during image formation in the image forming apparatus of FIG. 1. FIG. 4 is a flowchart of a program executed in the determination block of FIG. 3. FIG. 4 is a diagram illustrating a state where toner is clogged in a vertical portion of the conveyance tube in FIG. 3. It is a figure which shows the structure of the powder conveying apparatus of 2nd Embodiment which concerns on this invention.

  Hereinafter, embodiments of a powder conveying apparatus and an image forming apparatus according to the present invention will be described with reference to the accompanying drawings.

(Image forming device)
FIG. 1 shows an image forming apparatus 10 as an example of an image forming apparatus according to the present invention. The image forming apparatus 10 includes a sheet storage unit 12 that stores recording paper P from the lower side to the upper side in the vertical direction (arrow V direction), and a sheet storage unit 12 that is provided on the sheet storage unit 12. An image forming unit 14 that forms an image on recording paper P as an example of a supplied recording medium, a document reading unit 16 that is provided on the image forming unit 14 and that reads a read document G, and is provided in the image forming unit 14. And a control unit 20 that controls the operation of each unit of the image forming apparatus 10. In the following description, the vertical direction of the apparatus main body 10A of the image forming apparatus 10 is described as an arrow V direction, and the horizontal direction is described as an arrow H direction.

  The sheet storage unit 12 is provided with a first storage unit 22, a second storage unit 24, and a third storage unit 26 that store recording sheets P of different sizes. The first storage unit 22, the second storage unit 24, and the third storage unit 26 are provided with a delivery roll 32 that sends the stored recording paper P to a conveyance path 28 provided in the image forming apparatus 10. A pair of transport rolls 34 and transport rolls 36 that transport the recording paper P one by one are provided on the transport path 28 downstream of the feed roll 32. Further, the recording paper P is temporarily stopped on the downstream side of the transport roll 36 in the transport direction of the recording paper P in the transport path 28 and to a secondary transfer position QB (see FIG. 2) described later at a predetermined timing. An alignment roll 38 is provided.

  The upstream portion of the conveyance path 28 (the portion where the conveyance roll 36 is provided) extends from the left side of the sheet storage unit 12 to the lower left side of the image formation unit 14 in the direction of arrow V in the front view of the image forming apparatus 10. It is provided in a straight line. The downstream portion of the conveyance path 28 is provided from the lower left portion of the image forming portion 14 to the paper discharge portion 15 provided on the right side surface of the image forming portion 14. Further, a double-sided conveyance path 29 through which the recording paper P is conveyed and reversed in order to form an image on both sides of the recording paper P is connected to the conveyance path 28.

  The duplex conveyance path 29 includes a first switching member 31 that switches between the conveyance path 28 and the duplex conveyance path 29 from the lower right side of the image forming unit 14 to the right side of the sheet storage unit 12 in a front view of the image forming apparatus 10. The reversing unit 33 linearly provided in the direction of arrow V (downward is −V, upward is + V), and the trailing edge of the recording paper P conveyed to the reversing unit 33 enters and is illustrated in the direction of arrow H. It has the conveyance part 37 conveyed to the left side, and the 2nd switching member 35 which switches the inversion part 33 and the conveyance part 37. FIG. The reversing unit 33 is provided with a pair of conveyance rolls 42 at intervals, and the conveyance unit 37 is provided with a pair of conveyance rolls 44 at intervals.

  The first switching member 31 is a triangular prism-shaped member, and the conveyance direction of the recording paper P is changed by moving the leading end to either the conveyance path 28 or the double-sided conveyance path 29 by a driving unit (not shown). It is supposed to switch. Similarly, the second switching member 35 is a triangular prism-shaped member when viewed from the front, and the leading end is moved to either the reversing unit 33 or the transport unit 37 by a driving unit (not shown), so that the recording paper P The conveyance direction is switched. The downstream end of the transport unit 37 is connected to the front side of the transport roll 36 in the upstream portion of the transport path 28 by a guide member (not shown). Further, a foldable manual sheet feeding unit 46 is provided on the left side surface of the image forming unit 14, and the conveyance path of the recording paper P fed from the manual sheet feeding unit 46 is an alignment roll in the conveyance path 28. It is connected to the front side (upstream side) of 38.

  The document reading unit 16 includes a document transport device 52 that automatically transports the read document G one by one, a platen glass 54 that is disposed below the document transport device 52 and on which one read document G is placed, and a document transport device. An original reading device 56 that reads the read original G conveyed by 52 or the read original G placed on the platen glass 54 is provided.

  The document conveyance device 52 has an automatic conveyance path 55 in which a plurality of pairs of conveyance rolls 53 are arranged, and a part of the automatic conveyance path 55 is arranged so that the recording paper P passes over the platen glass 54. . The original reading device 56 reads the read original G conveyed by the original conveying device 52 while being stationary at the left end of the platen glass 54, or is read on the platen glass 54 while moving in the arrow H direction. G is read.

  On the other hand, the image forming unit 14 includes an image forming unit 50 that forms a toner image (developer image). The image forming unit 50 includes a photoreceptor 62, a charging member 64, an exposure device 66, a developing device 70, and a cleaning device 73.

  In the center of the apparatus main body 10A in the image forming unit 14, a photoconductor 62 as an example of an image carrier is provided. The photosensitive member 62 has a cylindrical shape, and rotates in a direction (clockwise direction) indicated by an arrow + R by a driving unit (not shown) and holds an electrostatic latent image formed by light irradiation. Yes. A corotron charging member 64 that charges the surface of the photoconductor 62 is provided above the photoconductor 62 and at a position facing the outer peripheral surface of the photoconductor 62.

  An exposure device 66 is provided at a position downstream of the charging member 64 in the rotation direction of the photoconductor 62 and facing the outer peripheral surface of the photoconductor 62. The exposure device 66 has a semiconductor laser (not shown), an f-θ lens, a polygon mirror, an imaging lens, and a plurality of mirrors, and deflects and scans the laser beam emitted from the semiconductor laser based on the image signal by the polygon mirror. Then, the outer peripheral surface of the photosensitive member 62 charged by the charging member 64 is irradiated (exposed) to form an electrostatic latent image. The exposure device 66 is not limited to a method of deflecting and scanning laser light with a polygon mirror, but may be an LED (Light Emitting Diode) method.

  The electrostatic latent image formed on the outer peripheral surface of the photoconductor 62 is developed with toner of a predetermined color on the downstream side of the portion irradiated with the exposure light of the exposure device 66 in the rotation direction of the photoconductor 62. A rotation switching type developing device 70 is provided for visualization.

  As shown in FIG. 2, the developing device 70 includes yellow (Y), magenta (M), cyan (C), black (K), first special color (E), and second special color (F) toners. Developing units 72Y, 72M, 72C, 72K, 72E, and 72F corresponding to the colors are arranged side by side in the circumferential direction (in this order in the counterclockwise direction shown in the figure), and the central angle is set by a motor (not shown). , The developing devices 72Y, 72M, 72C, 72K, 72E, and 72F that perform the development processing are switched to face the outer peripheral surface of the photosensitive member 62. The first special color E and the second special color F are selected from special colors (including transparent) other than yellow, magenta, cyan, and black. Each of the developing devices 72Y, 72M, 72C, 72K, 72E, and 72F is supplied with toner of each toner color from replaceable toner cartridges 78Y, 78M, 78C, 78K, 78E, and 78F (see FIG. 1). .

  In FIG. 2, since the developing devices 72Y, 72M, 72C, 72K, 72E, and 72F have the same configuration, the developing device 72Y will be described here as a representative.

  The developing device 72Y includes a case member 76 serving as a main body. In the case member 76, toner and carrier supplied from a toner cartridge 78Y (see FIG. 1) via a toner supply path (not shown). A developer (not shown) is filled. The case member 76 is formed with a rectangular opening 76 </ b> A facing the outer peripheral surface of the photoconductor 62, and the developing roll whose outer peripheral surface faces the outer peripheral surface of the photoconductor 62 is formed in the opening 76 </ b> A. 74 is provided. Further, a plate-like regulating member 79 for regulating the layer thickness of the developer is provided along the longitudinal direction of the opening 76A at a portion near the opening 76A in the case member 76.

  The developing roller 74 includes a cylindrical developing sleeve 74A that is rotatably provided, and a magnetic member 74B that includes a plurality of magnetic poles fixed inside the developing sleeve 74A. The developing sleeve 74A rotates. Thus, the developer (carrier) magnetic brush is formed, and the layer thickness is regulated by the regulating member 79, whereby the developer layer is formed on the outer peripheral surface of the developing sleeve 74A. The developer layer on the outer peripheral surface of the developing sleeve 74A is conveyed to a position facing the photoconductor 62 by the rotation of the developing sleeve 74A, and becomes a latent image (electrostatic latent image) formed on the outer peripheral surface of the photoconductor 62. Development is performed by attaching a suitable toner.

  Further, in the case member 76, two spirally formed transport rolls 77 are arranged in parallel so as to be rotatable, and the two transport rolls 77 are rotated so that the case member 76 is filled. The developer is circulated and conveyed in the axial direction of the developing roll 74 (longitudinal direction of the developing device 72Y). The six developing rolls 74 provided in each of the developing units 72Y, 72M, 72C, 72K, 72E, and 72F are arranged in the circumferential direction so that the distance from the adjacent developing roll 74 is a central angle of 60 °. Then, by switching the developing device 72, the next developing roll 74 is opposed to the outer peripheral surface of the photosensitive member 62.

  As shown in FIG. 2, a toner image formed on the outer peripheral surface of the photoconductor 62 is formed on the recording paper P on the downstream side of the developing device 70 in the rotation direction of the photoconductor 62 and below the photoconductor 62. A transfer device 58 for transferring is provided. The transfer device 58 has an intermediate transfer belt 68. The intermediate transfer belt 68 is endless, and is driven by being in contact with the drive roll 61 that is rotationally driven by the control unit 20, the tension applying roll 65 for applying tension to the intermediate transfer belt 68, and the back surface of the intermediate transfer belt 68. It is wound around a plurality of rotating transport rollers 63 and an auxiliary roller 69 that rotates in contact with the back surface of the intermediate transfer belt 68 at a secondary transfer position QB described later. The intermediate transfer belt 68 rotates in the direction indicated by the arrow -R (counterclockwise direction) as the driving roll 61 rotates.

  A primary transfer roll 67 is provided on the opposite side of the photoreceptor 62 across the intermediate transfer belt 68 to primarily transfer the toner image formed on the outer peripheral surface of the photoreceptor 62 to the intermediate transfer belt 68. The primary transfer roll 67 is located at a position away from the position where the photoreceptor 62 and the intermediate transfer belt 68 are in contact (this is referred to as the primary transfer position QA) to the downstream side in the moving direction of the intermediate transfer belt 68. It is in contact with the back side. When the primary transfer roll 67 is energized from a power source (not shown), the toner image on the photoreceptor 62 is primarily transferred to the intermediate transfer belt 68 by a potential difference from the grounded photoreceptor 62. Yes.

  Further, on the opposite side of the auxiliary roll 69 across the intermediate transfer belt 68, a secondary transfer roll 71 for secondary transfer of the toner image primarily transferred onto the intermediate transfer belt 68 onto the recording paper P is provided. A space between the secondary transfer roll 71 and the auxiliary roll 69 is a secondary transfer position QB where the toner image is transferred onto the recording paper P. The secondary transfer roll 71 is grounded and is in contact with the surface of the intermediate transfer belt 68. The intermediate transfer belt 68 is caused by a potential difference between the auxiliary roll 69 and the secondary transfer roll 71 energized from a power source (not shown). The toner image is secondarily transferred to the recording paper P. The secondary transfer position QB is set in the middle of the above-described transport path 28 (see FIG. 1).

  A cleaning blade 59 that collects residual toner after secondary transfer of the intermediate transfer belt 68 is provided on the opposite side of the drive roll 61 with the intermediate transfer belt 68 interposed therebetween. The cleaning blade 59 is attached to a housing (not shown) in which an opening is formed, and the toner scraped off at the tip of the cleaning blade 59 is collected in the housing.

  A predetermined reference position on the intermediate transfer belt 68 is detected by detecting a mark (not shown) attached to the surface of the intermediate transfer belt 68 at a position facing the conveyance roll 63 around the intermediate transfer belt 68. In addition, a position detection sensor 83 that outputs a position detection signal that serves as a reference for the start timing of the image forming process is provided. The position detection sensor 83 detects the moving position of the intermediate transfer belt 68 by irradiating the intermediate transfer belt 68 with light and receiving light reflected by the surface of the mark.

  On the other hand, on the downstream side of the primary transfer roll 67 in the rotation direction of the photoconductor 62, a cleaning device 73 is provided for cleaning toner remaining on the surface of the photoconductor 62 without being primarily transferred to the intermediate transfer belt 68. . The cleaning device 73 is configured to collect toner by a cleaning blade 73A and a brush roll 73B that are in contact with the surface of the photoreceptor 62.

  On the bottom wall of the case body 73 </ b> C of the cleaning device 73, a powder conveyance device 100 is provided for conveying toner as an example of the powder collected by the cleaning device 73 to the outside. Details of the powder conveying apparatus 100 will be described later.

  Further, a corotron 81 is provided on the upstream side of the cleaning device 73 in the rotation direction of the photosensitive member 62 (downstream side of the primary transfer roll 67) to remove the toner remaining on the outer peripheral surface of the photosensitive member 62 after the primary transfer. ing. Further, on the downstream side of the cleaning device 73 in the rotation direction of the photoconductor 62 (upstream side of the charging member 64), a static elimination device 75 is provided for performing static elimination by irradiating the outer peripheral surface of the photoconductor 62 after cleaning. It has been.

  As shown in FIG. 1, the toner transferred to the recording paper P by the secondary transfer roll 71 on the downstream side of the secondary transfer roll 71 in the transport direction (shown by arrow A) of the recording paper P in the transport path 28. A fixing device 90 for fixing the image as a permanent image is provided. A decurler 39 is provided on the downstream side of the fixing device 90 in the conveyance direction of the recording paper P to correct and flatten the deformation (wrinkles, deflection, etc.) of the recording paper P fixed by the fixing device 90. Yes.

  Next, an image forming process in the image forming apparatus 10 will be described.

  When the image forming apparatus 10 is activated, yellow (Y), magenta (M), cyan (C), black (K), the first special color (E), and the second special are supplied from an image processing apparatus (not shown) or from the outside. The image data of each color (F) is sequentially output to the exposure device 66. At this time, as an example, the developing device 70 is rotated and held so that the developing device 72 </ b> Y (see FIG. 2) faces the outer peripheral surface of the photoreceptor 62.

  Subsequently, the light emitted from the exposure device 66 according to the image data exposes the outer peripheral surface (front surface) of the photosensitive member 62 charged by the charging member 64, and yellow image data is formed on the surface of the photosensitive member 62. A corresponding electrostatic latent image is formed. Further, the electrostatic latent image formed on the surface of the photoreceptor 62 is developed as a yellow toner image by the developing device 72Y. Then, the yellow toner image on the surface of the photoconductor 62 is transferred to the intermediate transfer belt 68 by the primary transfer roll 67.

  Subsequently, the developing device 70 is rotated by 60 ° in the direction indicated by the arrow + R, and the developing device 72M faces the surface of the photosensitive member 62. Then, charging, exposure, and development processes are performed, and the magenta toner image on the surface of the photoconductor 62 is transferred by the primary transfer roll 67 so as to overlap the yellow toner image on the intermediate transfer belt 68. Similarly, toner images of cyan (C), black (K), first special color (E), and second special color (F) are sequentially transferred onto the intermediate transfer belt 68 in a multiple transfer manner.

  On the other hand, the recording paper P sent out from the paper storage unit 12 and transported through the transport path 28 is subjected to a secondary transfer position in synchronization with the multiple transfer of each toner image onto the intermediate transfer belt 68 by the positioning roll 38. Transported to QB. The toner image that has been multiplex-transferred onto the intermediate transfer belt 68 is secondarily transferred by the secondary transfer roll 71 onto the recording paper P that has been transported to the secondary transfer position QB.

  Subsequently, the recording paper P onto which the toner image has been transferred is conveyed toward the fixing device 90 in the direction indicated by the arrow A in FIG. In the fixing device 90, the toner image on the recording paper P is fixed as a permanent image. The fixed recording paper P is deformed (wrinkles, bent, etc.) by the decurler 39 and discharged to the paper discharge unit 15. When images are formed on both sides of the recording paper P, the recording paper P is image-formed and fixed on the surface, and then sent to the reversing unit 33 to be reversed and the secondary transfer position QB. Is transported again. Then, image formation and fixing are performed on the back surface of the recording paper P.

(Powder conveying apparatus of the first embodiment)
Next, the structure of the powder conveyance apparatus 100 of 1st Embodiment is demonstrated.

  As shown in FIG. 3, the powder conveyance device 100 includes a conveyance tube 102 that is continuously formed on the bottom wall of the case body 73 </ b> C of the cleaning device 73 and conveys the toner therein, and supplies the toner inside the conveyance tube 102. And an auger 104 as an example of conveying means for conveying.

  The transport pipe 102 includes a vertical portion 106 that extends downward from the bottom wall of the case body 73 </ b> C of the cleaning device 73, and a horizontal portion 108 that extends in the horizontal direction from the vertical portion 106. The toner is conveyed by free fall in the vertical portion 106 of the conveyance tube 102 and is conveyed by the auger 104 in the horizontal portion 108.

  The auger 104 has a spiral blade around the rotation axis, and one end of the auger 104 is connected to the motor 110. The auger 104 is rotated when the power of the motor 110 is transmitted. When the auger 104 is rotated in the direction indicated by the arrow A in the figure, the toner is conveyed in the direction indicated by the arrow B in the figure.

  A temperature regulator 112 as an example of a temperature difference generation and maintenance unit is attached to the outer peripheral surface of the horizontal portion 108 of the transport pipe 102. For example, the temperature regulator 112 can acquire the temperature of the toner at the point X in the figure, and the temperature of the conveyance tube 102 at the attached site is predetermined with respect to the acquired toner temperature. A temperature difference is generated, for example, a temperature difference that is as high as 10 ° C. is generated, and the temperature of the conveyance pipe 102 in a portion attached is adjusted so that the temperature difference is maintained.

A heat flux detection sensor 114 is attached to a position on the inner peripheral surface of the horizontal portion 108 of the transport pipe 102 and facing the temperature regulator 112. The heat flux detection sensor 114 outputs a signal corresponding to the heat flux generated by the temperature difference between the temperature of the conveyance tube 102 and the temperature of the toner at the site where it is attached. The heat flux indicates the amount of heat energy flowing through the unit area, and the unit is represented by W / m ² . The heat flux detection sensor 114 is shown as thick in the drawing for convenience of explanation, but it has a thickness that does not hinder toner conveyance.

  The output value M output by the heat flux detection sensor 114 is sent to a determination block 116 as an example of a determination unit. The determination block 116 is one of the control blocks provided in the control unit 20, and includes a microcomputer including a CPU, a memory, and a ROM. The determination block 116 determines the toner conveyance state inside the conveyance tube 102 based on the output value M transmitted from the heat flux detection sensor 114 as will be described later, and the alarm device 118 and the auger 104 according to the determination result. The operation of the (motor 110) is controlled.

  4 to 7 show the relationship between the toner conveyance state inside the conveyance tube 102 and the output value M of the heat flux detection sensor 114. FIG.

As shown in FIGS. 4 and 5, when the toner flows in the conveying pipe 102 at a flow rate V as the auger 104 rotates, the output value M indicating the heat flux of the heat flux detection sensor 114 is the fluid heat. Communication is dominant. The heat flux amount Q (W) due to fluid heat transfer is given by the following equation.
Q = hA (Tw−Ta) (1)

In formula (1), h is the heat transfer coefficient (W / (m ² · K)), A is the heat transfer area (m ² ), Tw is the object surface temperature (K), and Ta is the fluid temperature (K). . The heat transfer coefficient h is a function parameter that depends on the flow rate of the fluid and the thermal conductivity of the fluid. Here, the heat transfer area A is specifically a detection area of the heat flux detection sensor 114. Here, the object surface temperature Tw is specifically the temperature of the transport pipe 102 that is adjusted by the temperature adjuster 112. Fluid temperature Ta, here specifically the temperature of the toner.

  As shown in FIGS. 4 and 5, when the toner flow rate V increases, the output value M indicating the heat flux of the heat flux detection sensor 114 increases. This is because the amount of heat energy taken from the conveying tube 102 increases as the toner flow rate V increases.

When the toner is clogged inside the conveying tube 102 as shown in FIG. 6 or when there is no toner inside the conveying tube 102 as shown in FIG. In this case, the output value M indicating the heat flux of the heat flux detection sensor 114 is predominantly due to the heat conduction of the object. The heat flux q (W / m ² ) due to body heat conduction is given by the following equation.
q = −k · gradT (2)

In Equation (2), k represents thermal conductivity (W / (m ² · K)), and gradT represents a temperature gradient (K) on the object surface. The thermal conductivity k is a physical property value specific to an object in which heat transfer occurs, and is specifically an intrinsic thermal conductivity of toner or an intrinsic thermal conductivity of air. Here, the temperature gradient gradT on the surface of the object is specifically the temperature difference between the temperature of the conveyance tube 102 and the toner temperature that is specifically adjusted by the temperature regulator 112 or the temperature of the conveyance tube 102 that is adjusted by the temperature regulator 112. And the temperature of the air inside the transport pipe 102.

  As shown in FIGS. 6 and 7, the output value M indicating the heat flux of the heat flux detection sensor 114 is lower than that in the case where the toner flows in FIGS. 4 and 5. This is because the heat transfer due to object heat conduction is gentler than the heat transfer due to fluid heat transfer, and the amount of heat energy taken away from the transport pipe 102 is small.

  Further, the output value indicating the heat flux of the heat flux detection sensor 114 is greater when the toner is not present inside the transport tube 102 of FIG. 7 than when the toner is clogged inside the transport tube 102 of FIG. 6. M indicates a low value. This is because the intrinsic thermal conductivity of air is smaller than the intrinsic thermal conductivity of toner, and the amount of thermal energy taken away from the conveying tube 102 by air is smaller than the amount of thermal energy taken away from the conveying tube 102 by toner. Because.

  As described above, the output value M of the heat flux detection sensor 114 varies depending on the toner conveyance state inside the conveyance tube 102. Based on this, the determination block 116 determines the toner transport state inside the transport tube 102 based on the output value M. That is, the determination block 116 determines that the toner is clogged inside the transport tube 102 when the output value M of the heat flux detection sensor 114 is within a predetermined range.

  If the determination block 116 determines that the toner is clogged inside the conveyance tube 102, the alarm block 118 or the auger 104 (motor 110) issues a command to clear the toner clogging state. send. Specifically, an instruction to sound an alarm device 118 is sent to the engineer to prompt the cleaning of the inside of the transport pipe 102, and the operation of the auger 104 (motor 110) to break the toner clogged inside the transport pipe 102. A command is sent to increase the speed or to temporarily reverse the direction of operation of the auger 104 (motor 110).

  FIG. 8 shows the passage of time of the output value M of the heat flux detection sensor 114 during image formation in the image forming apparatus 10.

  As shown in FIG. 8, in the image formation preparation process, the output value M of the heat flux detection sensor 114 shows a high value. The image formation preparation step is performed at the time of setup such as replacement of a new image forming unit 50 including the photoconductor 62. In the image formation preparation step, the toner is exposed so that a toner band is formed on the surface of the photoconductor 62. A large amount is supplied to the surface of the body 62. In the image formation preparation process, since the primary transfer is not performed at the primary transfer position QA, a large amount of toner is collected by the cleaning device 73, and a large amount of toner flows through the conveyance tube 102 of the powder conveyance device 100. For this reason, in the image formation preparation process, the output value M of the heat flux detection sensor 114 shows a high value.

  In the image forming process, the primary transfer is performed at the primary transfer position QA, and the toner remaining on the surface of the photoconductor 62 without being primarily transferred to the intermediate transfer belt 68 is collected by the cleaning device 73, so that the powder transport device 100 A small amount of toner flows through the transport pipe 102. Therefore, the output value M of the heat flux detection sensor 114 is lower in the image forming process than in the image forming preparation process.

  When the image forming process is completed, the amount of toner collected by the cleaning device 73 is gradually reduced, so that the amount of toner flowing to the conveyance tube 102 of the powder conveyance device 100 is also gradually reduced. Therefore, the output value M of the heat flux detection sensor 114 gradually decreases.

  When a predetermined time tref, for example, about 10 seconds elapses after the image forming process is completed, all the toner in the transport tube 102 is transported and no toner is present in the transport tube 102 (normal state). . Then, the output value M of the heat flux detection sensor 114 becomes substantially zero. On the other hand, when the output value M of the heat flux detection sensor 114 does not become substantially zero and remains high even after the predetermined time tref has elapsed after the image forming process is finished (the output value M of the heat flux detection sensor 114 is If it is within a predetermined range), it is considered that the toner is clogged (abnormal state) inside the conveyance tube 102.

  FIG. 9 is a flowchart of a program executed in the determination block. This program is executed every predetermined time (for example, 100 msec) after the image forming apparatus 10 is turned on.

  First, in step S10, it is determined whether or not there is an image formation instruction. If the result in step S10 is negative, the program is terminated as it is. If the result is positive, the program proceeds to the next step S12 to start the operation of the auger 104.

  Next, in step S14, it is determined whether or not the image forming process is finished. If it is determined in step S14 that the image forming process has been completed, the process proceeds to step S16 to determine whether or not a predetermined time tref has elapsed since the end of the image forming process. If it is determined in step S16 that a predetermined time tref has elapsed from the end of the image forming process, the process proceeds to step S18, where the output value M of the heat flux detection sensor 114 is the toner presence / absence determination threshold value Mref (see FIG. 8). It is judged whether it is less than.

  If the determination in step S18 is affirmative, the process proceeds to step S20, where it is determined that the toner is not clogged inside the conveyance tube 102. Next, the process proceeds to step S22, the operation of the auger 104 is terminated, and this program is terminated.

  On the other hand, when the result in Step S20 is negative, the process proceeds to Step 24, where it is determined that the toner tube is in an abnormal state where the toner is clogged. Next, the routine proceeds to step 28 where the operation of the auger 104 is increased or the operation of the auger 104 is temporarily reversed. As a result, the toner clogged inside the transport tube 102 is destroyed. Next, the process returns to step S18. If the determination here is affirmative, the program is terminated through steps S20 and S22. In the case where the negative is continuously made several times in step S18, for example, in the case where the negative is continuously made three times, the process proceeds to step S26 and the alarm device 118 is sounded. This prompts the engineer to clean the inside of the transfer tube 102. Thereafter, the process returns to step S18. If the determination is affirmative, the program is terminated through steps S20 and S22.

  As shown in FIG. 10, when the toner is clogged in the vertical portion 106 of the transport pipe 102, the result is affirmative in step 18 in spite of the abnormal state in which the toner is clogged, and the normal state. Determined. Therefore, the second heat flux detection sensor 120 and the second temperature regulator 122 are attached to the vertical portion 106 of the transport pipe, and the vertical portion of the transport pipe 102 is based on the output value M ′ of the second heat flux detection sensor 120. It is preferable that the toner clogging 106 can be determined.

(Powder conveying apparatus of 2nd Embodiment)
FIG. 11 shows the configuration of the powder conveyance device 200 of the second embodiment. In the powder conveyance device 200 of the second embodiment, the heat flux detection sensor 114 in the powder conveyance device 100 of the first embodiment is removed, and a power detection sensor 124 is provided instead.

  The temperature regulator 112 is supplied with power from an external power supply source (not shown), and can acquire the temperature of the toner at, for example, the point X in the figure. A predetermined temperature difference with respect to the temperature of the toner to be acquired is generated, for example, a temperature difference that is higher by 10 ° C. is generated, and the portion of the part that is attached so as to maintain the temperature difference is generated. The temperature of the transfer tube 102 is adjusted.

  The power detection sensor 124 is provided in the temperature regulator 112 and outputs a signal corresponding to the power received from the external power supply source, that is, the power consumed by the temperature regulator 112 to adjust the temperature of the transfer tube 102. It is configured as follows. Then, the output value N of the power detection sensor 124 is sent to the determination block 116.

  When the toner is flowing inside the conveyance tube 102, the output value N of the power detection sensor 124 increases as the toner flow rate V increases. This is because as the toner flow rate V increases, the amount of heat energy taken from the transport tube 102 increases, and the power consumed by the temperature regulator 112 increases.

  When the toner is clogged inside the conveyance tube 102, the output value N of the power detection sensor 124 is smaller than that when the toner flows inside the conveyance tube 102. This is because heat transfer by object heat conduction is more gradual than heat transfer by fluid heat transfer, and the amount of heat energy taken away from the transfer tube 102 is small, and less power is consumed by the temperature regulator 112. It is.

  When no toner is present inside the transport tube 102, the output value N of the power detection sensor 124 is smaller than when the toner is clogged inside the transport tube 102. This is because the intrinsic thermal conductivity of air is smaller than the intrinsic thermal conductivity of toner, and the amount of thermal energy taken away from the carrier tube by the air is smaller than the amount of thermal energy taken away from the carrier tube 102 by the toner, This is because less power is consumed by the temperature regulator 112.

  As described above, the output value N of the power detection sensor 124 varies depending on the toner conveyance state inside the conveyance tube 102. Based on this, the determination block 116 determines the toner conveyance state inside the conveyance tube 102 based on the output value N. That is, the determination block 116 determines that the toner is clogged inside the transport tube 102 when the output value N of the power detection sensor 124 is within a predetermined range.

  The determination block 116 controls the operation of the alarm device 118 and the auger 104 (motor 110) according to the determination result. Specifically, when the determination block 116 determines that the toner is clogged inside the transport pipe 102, the alarm device 118 is sounded to prompt the engineer to clean the transport pipe 102, The operating speed of the auger 104 (the motor 110) is increased in order to break up the toner clogged in the interior 102, or the operating direction of the auger 104 (the motor 110) is temporarily reversed.

  As described above, in the powder conveyance device 100 according to the first embodiment, the temperature regulator 112 generates and maintains a predetermined temperature difference between the toner and the conveyance tube 102, so that the heat flow generated by the temperature difference is maintained. The bundle is detected by the heat flux detection sensor 114, and the toner conveyance state inside the conveyance tube 102 is determined based on the heat flux detected by the heat flux detection sensor 114. Therefore, the toner transport state is accurately detected.

  In the powder conveyance device 200 according to the second embodiment, the temperature regulator 112 is configured to generate and maintain a predetermined temperature difference between the toner and the conveyance tube 102 by the temperature regulator 112 that receives power supply. The power detected by the power detection sensor 124 is detected by the power detection sensor 124, and the toner transport state inside the transport pipe 102 is determined based on the power detected by the power detection sensor 124. Therefore, the toner transport state is accurately detected.

  In the powder conveyance device 100 of the first embodiment, the toner is clogged inside the conveyance tube 102 when the detection value M of the heat flux detection sensor 114 is within a predetermined range. It is determined to be present, and a command for canceling the state where the toner is clogged is issued. Therefore, the state where the toner is clogged in the inside of the conveyance tube 102 is eliminated.

  In the powder conveyance device 200 of the second embodiment, the toner is clogged inside the conveyance tube 102 when the detection value N of the power detection sensor 124 is within a predetermined range. And a command for eliminating the state where the toner is clogged is issued. Therefore, the state where the toner is clogged in the inside of the conveyance tube 102 is eliminated.

  In the powder conveyance device 100 according to the first embodiment and the powder conveyance device 200 according to the second embodiment, a command for increasing the operating speed of the auger 104 as a command for eliminating the toner clogging state. Or it is comprised so that the instruction | command which reverses the operation | movement direction of the auger 104 may be issued. Therefore, the state where the toner is clogged inside the conveyance tube 102 is easily eliminated.

  In the image forming apparatus 10, the photosensitive member 62 on which the electrostatic latent image is formed, the developing device 70 that develops the electrostatic latent image formed on the photosensitive member 62 with toner, and the developing device 70 develops the electrostatic latent image. The transfer device 58 that transfers the toner image to the recording paper P, and the powder transfer device 100 (or the powder transfer device 200) that transfers the toner that has not been transferred by the transfer device 58 out of the toner supplied from the developing device 70. ). Therefore, the image forming apparatus 10 including the powder conveyance device 100 (or the powder conveyance device 200) capable of accurately detecting the toner conveyance state is provided.

  In addition, this invention is not limited to said embodiment.

  That is, the temperature regulator 112 as an example of the temperature difference generation and maintenance means is configured such that the temperature of the transport pipe 102 is higher than the toner temperature by a predetermined temperature. However, the temperature of the conveying tube 102 may be lower than the temperature of the toner by a predetermined temperature.

  Further, although the auger 104 has been exemplified as the conveying means, the free fall in the vertical portion 106 of the conveying pipe 102 is also included in the conveying means here.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 58 Transfer apparatus 62 Photosensitive body (an example of an image holding body)
70 Developing Device 100 Powder Conveying Device (First Embodiment)
102 Conveying pipe 104 Auger (an example of conveying means)
106 Vertical portion 108 Horizontal portion 110 Motor 112 Temperature adjuster (an example of temperature difference generation adjusting means)
114 heat flux detection sensor 116 determination block (an example of determination means)
118 Alarm Device 120 Second Heat Flux Detection Sensor 122 Second Temperature Controller (Example of Temperature Difference Generation Adjusting Unit)
124 Electric power detection sensor 200 Powder conveying apparatus (2nd Embodiment)
P Recording paper (an example of a recording medium)

Claims (6)

A transport tube;
Conveying means for conveying the powder inside the conveying tube;
A temperature difference generation maintaining means for generating and maintaining a predetermined temperature difference between the powder and the transport pipe;
A heat flux detection sensor for detecting a heat flux generated by the temperature difference;
Determination means for determining the state of conveyance of the powder inside the conveyance pipe based on the heat flux detected by the heat flux detection sensor;
A powder conveying apparatus comprising: A transport tube;
Conveying means for conveying the powder inside the conveying tube;
A temperature difference generating and maintaining means for receiving and supplying a power to generate and maintain a predetermined temperature difference between the powder and the transport pipe;
A power detection sensor for detecting the power consumed by the temperature difference occurrence maintaining means;
Determination means for determining a state of conveyance of the powder inside the conveyance tube based on electric power detected by the electric power detection sensor;
A powder conveying apparatus comprising:   When the heat flux detected by the heat flux detection sensor is within a predetermined range, the determination means determines whether the powder is transported inside the transport pipe when the powder is in the transport pipe. The powder conveying apparatus according to claim 1, wherein the powder conveying device is determined to be in a clogged state and issues a command for eliminating the clogged state of the powder.   The determination means is configured such that when the power detected by the power detection sensor is within a predetermined range, the powder transport state inside the transport pipe is clogged with the powder inside the transport pipe. The powder conveying apparatus according to claim 2, wherein the powder conveying device issues a command for eliminating the state where the powder is clogged.   The said determination means issues the instruction | command which increases the operating speed of the said conveyance means, or the instruction | command which reverses the operation direction of the said conveyance means as a command for canceling the state where the said powder is clogged. 4. The powder conveying apparatus according to 4. An image carrier on which an electrostatic latent image is formed;
A developing device for developing the electrostatic latent image formed on the image carrier with powder;
A transfer device for transferring the powder image developed by the developing device to a recording medium;
The powder conveying apparatus according to any one of claims 1 to 5, which conveys powder that has not been transferred by the transfer apparatus among powder supplied from the developing device,
An image forming apparatus comprising: