JP6337609B2 - Flow velocity measuring apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a flow velocity measuring device that measures the flow velocity of powder that is conveyed in a conveyance path, and more particularly, a flow velocity measurement device that is suitable for measuring the flow velocity of toner that is conveyed in a conveyance path of an image forming apparatus as powder. And an image forming apparatus including the same.

In an electrophotographic image forming apparatus such as a digital copying machine or a laser printer, toner is used for image formation. In recent years, there is a tendency to use toner having a lower fixing temperature for energy saving. A toner that can be fixed at a low temperature can be produced by lowering the glass transition temperature of the main resin constituting the toner. However, a toner that can be fixed at a low temperature has a low mechanical strength and is liable to deteriorate in fluidity and agglomerate the toner, and thus easily causes problems such as clogging in the toner conveyance path.
In the image forming apparatus, toner is transported from the toner container and replenished to the developing device according to the amount of toner consumed during image formation. If the toner is clogged in the conveyance path, the toner density in the developing device decreases. If the amount of decrease in the toner density in the developing device is large, the image density on the recording medium may be reduced, resulting in a blurred image.

Here, since the toner in the transport path is transported using a transport screw or a pressure change in the transport path, the toner is likely to be mechanically stressed. As described above, the toner that can be fixed at a low temperature has low mechanical strength, and therefore the toner is likely to aggregate due to mechanical stress. When toner is clogged in the transport path, the toner flow rate in the transport path decreases as a precursor. If a decrease in the toner flow rate in the conveyance path can be accurately detected, problems such as toner clogging and associated image quality deterioration can be avoided.
As a conventional technique for detecting the state of toner in the conveyance path, Patent Document 1 describes an apparatus that detects a change in toner conveyance load using a piezoelectric vibrator or an ultrasonic sensor. Patent Document 2 describes a toner presence / absence detection device in which a magnetic permeability sensor is pressed against a lower portion or an outer surface of an outer peripheral surface of a toner storage device.

All of the above techniques only detect whether toner is present in a certain area. In other words, in the prior art, it is possible to detect whether or not the toner is clogged in the conveyance path, but it is difficult to detect a change in the toner flow rate.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a novel apparatus capable of detecting fluctuations in the flow rate of powder transported in a transport path.

In order to solve the above problems, the invention described in claim 1 is a flow velocity measuring apparatus for measuring a flow velocity of powder conveyed in a predetermined direction in a conveyance path, and a part thereof is supported by a support means. And a cantilever provided with a piezoresistor that outputs a beam portion arranged in the conveyance path, and an electric resistance value of deformation of the beam portion caused by contact of the conveyed powder, and the beam portion. Vibrating means for vibrating at a predetermined frequency and amplitude, and calculating means for deriving the flow velocity of the powder based on a change in frequency or amplitude of the beam portion detected as a change in resistance value output from the piezoresistor And.

  According to the present invention, since the flow velocity of the powder can be derived based on the resistance value output from the piezoresistor, it is possible to detect fluctuations in the conveyance flow rate of the powder conveyed in the conveyance path.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus to which the present invention is applied. FIG. 6 is a schematic diagram illustrating a state where a toner container is installed in the toner supply device. FIG. 3 is a partially enlarged view of a toner dropping conveyance path illustrated in FIG. 2. It is A arrow directional view of FIG. It is the top view which showed an example of the self-detection type SPM probe. It is a schematic diagram which shows the flow velocity measuring apparatus which concerns on 2nd embodiment. FIG. 3 is a partially enlarged view of a transport nozzle and a toner dropping transport path illustrated in FIG. 2. FIG. 3 is a partially enlarged view of a transport nozzle and a toner dropping transport path illustrated in FIG. 2.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .

[Image forming apparatus]
<Configuration>
FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus to which the present invention is applied.
The image forming apparatus 100 is a color printer that includes an intermediate transfer belt 8 as an intermediate transfer body on which a toner image is primarily transferred, and that can form a full-color image by an electrophotographic method using a tandem developing method.
A toner container storage unit 31 is disposed above the image forming apparatus 100. Four toner containers 32Y, 32M, 32C, and 32K corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), and black (K) are detachable (replaceable) in the toner container housing 31. Is installed. A primary transfer unit 15 (primary transfer unit) is disposed below the toner container housing 31. Four image forming units 6Y, 6M, 6C, and 6K corresponding to the respective colors are arranged in parallel so as to face the intermediate transfer belt 8 (intermediate transfer member or primary transfer member) of the primary transfer unit 15. The arrangement order of the colors of the image forming units is not limited to that shown in the figure, and other arrangement orders may be used.

Below the toner containers 32Y, 32M, 32C, and 32K, toner replenishing devices 60Y, 60M, 60C, and 60K are disposed, respectively. The toners stored in the toner containers 32Y, 32M, 32C, and 32K are respectively supplied to the developing devices 50Y, 50M, and 50C of the image forming units 6Y, 6M, 6C, and 6K by the toner replenishing devices 60Y, 60M, 60C, and 60K. , 50K is supplied (supplemented).
The image forming units 6Y, 6M, 6C, and 6K respectively include photosensitive drums 1Y, 1C, 1M, and 1K (image carriers) as image carriers, charging units and developing devices disposed around the photosensitive drums. 50Y, 50M, 50C, 50K, cleaning means and the like are provided. Each of the photosensitive drums 1Y, 1C, 1M, and 1K carries a single color toner image having a different color. The image forming units 6Y, 6M, 6C, and 6K are arranged at a predetermined pitch along the running direction of the intermediate transfer belt 8 so that the rotation axes of the photosensitive drums 1Y, 1C, 1M, and 1K are parallel to each other. Has been. The developing devices 50Y, 50M, 50C, and 50K included in the image forming units 6Y, 6M, 6C, and 6K have the same configuration except that different toner colors are used.
Below the image forming units 6Y, 6M, 6C, and 6K, a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like are provided, and lasers are applied to the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K based on the image data. An optical writing unit 7 (exposure apparatus) that irradiates while scanning the light L is disposed.

Above the image forming units 6Y, 6M, 6C, and 6K, a primary transfer unit including an intermediate transfer belt 8 on which the toner images formed by the image forming units 6Y, 6M, 6C, and 6K are superimposed and transferred. 15 is arranged.
The primary transfer unit 15 includes an intermediate transfer belt 8, four primary transfer rollers 9Y, 9C, 9M, and 9K, an intermediate transfer cleaning device 10, and the like. The intermediate transfer belt 8 is stretched and supported by a plurality of roller members, and is endlessly moved counterclockwise in FIG. 1 by the rotational drive of one roller member (secondary transfer backup roller 12).
The intermediate transfer cleaning device 10 includes a brush roller and a cleaning blade. The intermediate transfer cleaning device 10 is disposed so that the brush roller and the cleaning blade are in contact with the outer peripheral surface of the intermediate transfer belt 8. Foreign matter such as toner adhering to the intermediate transfer belt 8 is removed by the intermediate transfer cleaning device 10.
On the right side of the primary transfer unit 15 in the figure, a secondary transfer unit 16 (secondary transfer means, secondary transfer portion) for transferring the toner image carried and conveyed by the intermediate transfer belt 8 to the recording medium P is disposed. The secondary transfer unit 16 includes a secondary transfer roller 19 and a secondary transfer backup roller 12, and an intermediate transfer belt 8 is sandwiched between the secondary transfer roller 19 and the secondary transfer backup roller 12, and a secondary transfer nip. Is forming.

A fixing unit 20 is disposed above the secondary transfer unit 16. The fixing unit 20 includes a fixing belt and a pressure roller, and fixes the color toner image secondarily transferred onto the surface of the recording medium P onto the recording medium P by heat and pressure.
A discharge roller pair 29 for discharging the recording medium P on which an image has been formed to the outside of the apparatus is provided downstream of the fixing unit 20 in the conveyance direction of the recording medium P. The recording medium P discharged outside the apparatus through the pair of paper discharge rollers 29 is sequentially stacked on the stack unit 30.
A duplex unit 18 is provided on the right side of the secondary transfer unit 16 and the fixing unit 20 in the drawing. The duplex unit 18 transfers the image onto the other side of the recording medium P by reversing the recording medium P on which the image has been transferred to one side and passing through the fixing unit 20 to the secondary transfer unit 16 while inverting it. Used for fixing.
At the bottom of the image forming apparatus 100, a paper feed cassette 26a is provided. In the paper feed cassette 26a, a plurality of recording media P such as transfer paper are stacked and stored. When the paper feed roller 27a is driven to rotate counterclockwise in FIG. 1, the uppermost recording medium P is fed toward the rollers of the registration roller pair 28.

Further, on the right side of the duplex unit 18 in the figure, a manual feed tray 26b that manually feeds from the side of the image forming apparatus is provided. When the paper feed roller 27 b is driven to rotate in the clockwise direction in FIG. 1, the uppermost recording medium P is fed toward the rollers of the registration roller pair 28.
Although not shown, the image forming apparatus 100 further includes a waste toner bottle, a power supply unit, and the like.

<Image forming operation>
An image forming operation will be described.
The photosensitive drum 1 is rotationally driven in a clockwise direction in FIG. 1 by a drive motor (not shown). Then, the surface of the photosensitive drum 1 is uniformly charged at a position facing the charging unit. A laser beam L based on image data is scanned by the optical writing unit 7 on the surface of the photosensitive drum 1 charged to a predetermined potential, and an electrostatic latent image of the corresponding color is written. When the surface of the photosensitive drum 1 carrying the electrostatic latent image reaches a position facing the developing device 50, toner is supplied to the electrostatic latent image on the surface of the photosensitive drum 1 to form a toner image.
The above operation is similarly performed at a predetermined timing in all the image forming units 6Y, 6M, 6C, and 6K, and toner images of a predetermined color are respectively formed on the surfaces of the photosensitive drums 1Y, 1C, 1M, and 1K. It is formed.
The intermediate transfer belt 8 is driven in accordance with the image forming operation timing of the image forming units 6Y, 6M, 6C, and 6K, and the toner images on the photosensitive drums 1Y, 1C, 1M, and 1K are sequentially transferred to the intermediate transfer belt 8. Is done. The transfer of the toner image is performed by a primary transfer roller 9Y, 9C, 9M, and 9K disposed opposite to the photosensitive drums 1Y, 1C, 1M, and 1K across the intermediate transfer belt 8 from a power source (not shown). This is performed by applying a voltage having a polarity opposite to that of the toner on 1Y, 1C, 1M, and 1K.

The recording medium P is transported from either the paper feed cassette 26 a or the manual feed tray 26 b and stops once when it reaches the registration roller pair 28. The recording medium P is conveyed from the registration roller pair 28 to the secondary transfer unit 16 in accordance with the image forming operation timing described above.
The four color toner images superimposed on the intermediate transfer belt 8 are transferred to the recording medium P at the nip portion (secondary transfer nip portion) between the secondary transfer roller 19 and the intermediate transfer belt 8. The transfer of the toner image is performed by applying a voltage having a polarity opposite to that of the toner on the intermediate transfer belt 8 from a power source (not shown) to the secondary transfer roller 19. The recording medium P is conveyed to the fixing unit 20 through the secondary transfer nip.
In the fixing unit 20, the toner image on the recording medium P is fixed by heat and pressure at a fixing nip between the fixing belt and the pressure roller. The recording medium P is conveyed by the fixing nip.
In the case of single-sided printing, the recording medium P on which an image is formed on one side is conveyed by each conveying roller, discharged between the rollers of the discharge roller pair 29 and discharged outside the apparatus, and stacked on the stack unit 30. . In the case of duplex printing, the sheet is conveyed to the duplex unit 18 by each conveyance roller.

<Control unit>
A control unit serving as a control unit that controls the operation of each unit of the image forming apparatus is a well-known computer device, and includes a CPU, a memory (ROM, RAM), and the like. The CPU reads the control program stored in the ROM, develops it in the RAM and executes it, thereby controlling the operation of each part of the image forming apparatus.

<Toner supply device>
The toner replenishing device 60 (Y, M, C, K) will be described. FIG. 2 is a schematic diagram illustrating a state in which a toner container is installed in the toner supply device.
The toner in each toner container 32 (Y, M, C, K) installed in the toner container accommodating portion 31 of the image forming apparatus 100 shown in FIG. 1 is developed by each color developing device 50 (Y, M, C, K). ) Is appropriately replenished in each developing device 50 (Y, M, C, K) according to the toner consumption in the bracket. At this time, the toner in each toner container 32 (Y, M, C, K) is replenished by a toner replenishing device 60 (Y, M, C, K) provided for each toner color.
The four toner replenishing devices 60 (Y, M, C, K) and the toner containers 32 (Y, M, C, K) have substantially the same structure except that the colors of toner used in the image forming process are different. . Therefore, only the toner replenishing device 60Y and toner container 32Y corresponding to yellow will be described below, and the toner replenishing device 60 (M, C, K) and toner container 32 (M, C) corresponding to the other three colors will be described. , K) will be omitted as appropriate.
The toner replenishing device 60 (Y, M, C, K) includes a toner container housing 31 (see FIG. 1), a transport nozzle 61 (Y, M, C, K), and a transport screw 62 (Y, M, C, K). ), A toner drop conveyance path 64 (Y, M, C, K), a rotation drive unit 91 (Y, M, C, K), and the like.

<Toner supply operation>
When the toner container 32Y moves in the direction of the arrow Q in the drawing and is mounted in the toner container housing portion 31 of the image forming apparatus 100, the toner replenishing device 60Y from the container front end side of the toner container 32Y is interlocked with the mounting operation. The transfer nozzle 61Y is inserted. As a result, the inside of the toner container 32Y communicates with the inside of the transport nozzle 61Y.
When rotation drive is input from the rotation drive unit 91Y to the container gear 35Y, the agitator 36Y as a powder conveying member provided in the container main body 33Y is rotated. By rotating the agitator 36Y, the toner accommodated in the container main body 33Y is conveyed from the left side to the right side in the drawing along the longitudinal direction of the container main body, and is supplied from the container front end side cover 34Y side into the conveyance nozzle 61Y. Is done.
A transport screw 62Y is disposed in the transport nozzle 61Y, and the transport screw 62Y rotates and is supplied into the transport nozzle 61Y when a rotational driving force is input to the transport screw gear 63Y from the rotation driving unit 91Y. Transports toner. The downstream end of the transport nozzle 61Y in the transport direction is connected to the toner drop transport path 64Y, and the toner transported by the transport screw 62Y falls in the toner drop transport path 64Y by its own weight and is supplied into the developing device 50Y.

  The control unit 90 may calculate the toner consumption based on the image information used in the optical writing unit 7 (exposure device) described above, and the control unit 90 may determine that it is necessary to supply the toner T to the developing device 50Y. . Further, the controller 90 may detect that the toner concentration in the developing device 50Y has decreased based on the detection result of the toner concentration detection sensor 56Y. In these cases, the rotation drive unit 91Y is driven under the control of the control unit 90, and the agitator 36Y and the transport screw 62Y in the container main body 33Y of the toner container 32Y are rotated for a predetermined time to supply toner to the developing device 50Y. .

[First embodiment]
A schematic configuration of the flow velocity measuring apparatus according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a partially enlarged view of the toner dropping conveyance path shown in FIG. 4 is a view taken in the direction of arrow A in FIG. The flow velocity measuring device is a means for measuring the flow velocity of powder such as toner conveyed along the toner conveyance path. Here, the powder is a collection of powders and grains. Examples of powders include building materials such as cement, food materials such as flour and sugar, materials such as cosmetics and pharmaceuticals, and the like.
The flow velocity measuring apparatus 200 includes a sensor unit 210 including a piezo-incorporated cantilever (hereinafter simply referred to as “cantilever”) 213 in which a piezoresistor 211 is integrated with a beam portion 214, and a signal (cantilever of the cantilever). And a calculation unit 220 for deriving the flow velocity of the toner conveyed in the toner dropping conveyance path 64.
The sensor unit 210 is installed in a transport path for transporting toner. In the present embodiment, the sensor unit 210 is disposed in the toner dropping conveyance path 64. Since the transport screw 62 is disposed in the transport nozzle 61 that transports the toner in a substantially horizontal direction, if the sensor unit 210 is disposed in the transport nozzle 61, the toner transport performance may be affected. In the present embodiment, the sensor unit is disposed in the toner dropping conveyance path 64 on the downstream side in the conveyance direction from the conveyance nozzle 61. In the toner drop transport path 64, the toner moves downstream due to free fall. Therefore, it is not necessary to install transport means such as a transport screw in the toner drop transport path 64. That is, by arranging the sensor unit 210 in the toner dropping conveyance path 64, the toner flow rate is not adversely affected to the toner conveyance performance and the sensor unit 210 is not affected by the conveyance means such as the conveyance screw. Can be measured.

  Thus, it is desirable that the sensor unit 210 be installed in a conveyance path portion where no conveyance means such as a conveyance screw is arranged. A particularly preferable conveyance path is a path that extends substantially vertically or obliquely up and down and allows the toner to fall by its own weight.

The sensor unit 210 includes a support member 215 (support means) that supports one end portion in the longitudinal direction of the beam portion 214 of the cantilever 213. Both ends in the longitudinal direction of the support member 215 are fixed at appropriate positions in the toner dropping conveyance path 64. The cantilever 213 is attached to the support member 215 such that the longitudinal direction intersects the longitudinal direction of the support member 215. The cantilever 213 is installed in the toner dropping conveyance path 64 so that its thickness direction (vertical direction in the drawing) is along the toner conveyance direction, in other words, the bending direction of the cantilever 213 is along the toner conveyance direction. .
The toner contacts the cantilever 213 when passing around the cantilever 213. The cantilever 213 in contact with the toner is bent and deformed in the conveying direction by the contact pressure. The flow velocity measuring device 200 measures the toner flow velocity based on the amount of deformation of the cantilever 213. The cantilever 213 is bent and deformed by an amount corresponding to the amount of toner conveyed in the toner dropping conveyance path 64. That is, the amount of bending of the cantilever 213 increases as the flow rate of toner increases, and the amount of bending of the cantilever 213 decreases as the flow rate of toner decreases.

Note that the cantilever 213 only needs to be installed in the toner dropping conveyance path 64 so as to be bent by the contact of the toner. Therefore, the cantilever 213 may be installed with its upper surface inclined in the longitudinal direction of the cantilever (left-right direction in FIG. 3). By tilting the surface of the cantilever 213, it becomes difficult for toner to adhere, and stable measurement sensitivity can be maintained over time.
Further, the cantilever 213 having the linear beam portion 214 shown in the figure is an example. Any other shape may be used as long as the cantilever has a beam portion having a shape that can be deformed according to the amount of toner in contact. In this case, at least a part (appropriate place) of the beam portion is supported by the support member 215 according to the shape of the beam portion.

In order to measure the toner flow rate with high sensitivity, it is necessary to design the mechanical rigidity of the cantilever 213 so that the cantilever 213 bends by an appropriate amount. For example, when the cantilever 213 is made of silicon, if the width is 50 [μm] × length is 400 [μm] × thickness is 10 [μm], when a toner having a flow rate of 1 [m / s] contacts, about 1 [ μstrain] will bend. If this amount of deflection can be secured, the cantilever 213 can measure the flow velocity of the toner. Note that when the cantilever 213 is actually mounted on the image forming apparatus, the mechanical rigidity (dimension) of the cantilever 213 is set so as to ensure an optimal amount of deflection suitable for various conditions of the image forming apparatus. Need to design.
The flow rate of the toner transported in the toner drop transport path 64 is obtained by multiplying the toner flow rate measured by the flow velocity measuring device 200 by the cross-sectional area of the toner drop transport path 64 (a known value at the design stage). be able to. Further, by continuously detecting this, it is possible to detect a change in the toner flow rate.

<Piezo built-in cantilever>
For the piezo built-in cantilever constituting the sensor unit 210 of this embodiment, for example, an SPM probe can be used. The schematic configuration and operation of the SPM probe will be described with reference to FIG. FIG. 5 is a plan view showing an example of the self-detecting SPM probe 700.
The self-sensing SPM probe 700 includes a cantilever 702 and piezoresistors 722 and 724 disposed on the surface of the cantilever 702. The cantilever 702 is bent and deformed in the conveyance direction by the contact pressure of the toner, and the electric resistance values of the piezoresistors 722 and 724 are changed. The self-detecting SPM probe 700 detects this resistance value as the deformation amount of the cantilever 702.
The self-detecting SPM probe 700 has a configuration in which a cantilever 702 is supported by a support portion 704. The base end portion of the cantilever 702 has two connection portions 706 and 708 extending substantially in parallel to the support portion 704, and the cantilever 702 is connected to the support portion 704 at the connection portions 706 and 708.

Piezoresistors 722 and 724 are formed in an approximately L shape at a portion from the base end portion of the cantilever 702 to a part of the support portion 704 via the connecting portions 706 and 708. Hereinafter, a specific portion including a portion where the piezoresistors 722 and 724 are formed is expressed as a bent portion. The cantilever 702 and the piezoresistors 722 and 724 are formed symmetrically about the line passing through the central portion in the width direction of the cantilever 702 in the longitudinal direction (vertical direction in the drawing) of the cantilever 702 as a central axis.
An insulating layer is formed on the piezoresistors 722 and 724 and the support portion 704. In FIG. 5, an insulating layer is not shown in order to simplify the drawing and facilitate understanding.

On the insulating layer, conductive layers 726 and 728 as wirings are formed. The conductive layers 726 and 728 are wirings for reading out the resistance values of the piezoresistors 722 and 724. The conductive layers 726 and 728 are formed from the base end portion of the cantilever 702 to the support portion 704 through the coupling portions 706 and 708. One end of each of the conductive layers 726 and 728 is disposed in a portion overlapping with the piezoresistors 722 and 724 located at the base end portion of the cantilever 702, and the other end of each of the conductive layers 726 and 728 is the piezoresistors 722 and 724. They are arranged on the support portions 704 that do not overlap each other.
At one end of the conductive layer 726, a metal contact portion 742 that electrically connects the piezoresistor 722 and the conductive layer 726 located in the lower layer is formed. Similarly, a metal contact portion 744 that electrically connects the piezoresistor 724 located in the lower layer and the conductive layer 728 is formed at one end of the conductive layer 728.
Further, conductive layers 732 and 734 as wirings are formed on the insulating layer. The conductive layers 732 and 734 are wirings for reading out the resistance values of the piezoresistors 722 and 724. One end of each of the conductive layers 732 and 734 is disposed at a portion overlapping with the piezoresistors 722 and 724 located in the support portion 704, and the other end of the conductive layers 732 and 734 is supported so as not to overlap with the piezoresistors 722 and 724. They are arranged on the portions 704, respectively.
At one end of the conductive layer 732, a metal contact portion 736 that electrically connects the piezoresistor 722 and the conductive layer 732 located in the lower layer is formed. Similarly, at one end of the conductive layer 734, a metal contact portion 738 that electrically connects the piezoresistor 724 located in the lower layer and the conductive layer 734 is formed.

Therefore, the change in the resistance value of the piezoresistor 722 can be read from the other end of each conductive layer 726, 732, and the change in the resistance value of the piezoresistor 724 can be read from the other end of each conductive layer 728, 734. Can be read out.
In the self-sensing SPM probe 700, the cantilever 702 and the support portion 704 are connected by two connecting portions 706 and 708. The piezoresistors 722 and 724 are formed from the cantilever 702 to the support portion 704 via connecting portions 706 and 708. Since the piezoresistors 722 and 724 can be thinly formed in the connecting portions 706 and 708, a difference in resistance value indicating a displacement difference between both bent portions caused by torsion of the cantilever 702 between the two piezoresistors is remarkable. And appear exactly.

  Further, changes in the resistance values of the piezoresistors 722 and 724 at the bent portions can be read out from the conductive layers 726, 732, 728, and 734 as wirings led on the support portion 704, and cantilevers can be obtained from the changes in the resistance values. The amount of twist 702 can be detected.

<Calculation processing of flow velocity measuring device>
The calculation unit 220 that processes a signal (a signal indicating a resistance value) from the sensor unit 210 will be described.

The calculation unit 220 includes a CPU (Central Processing Unit) that performs control operations according to a preset program, a ROM (Read Only Memory) that stores various programs and fixed data, and a RAM (Random) that serves as a work area for the CPU. Access Memory). The ROM stores the relationship between the resistance value of the piezoresistor incorporated in the cantilever and the toner flow rate in the form of a table or the like.
For example, the resistance value read from the conductive layer of the self-sensing SPM probe 700 shown in FIG. The calculation unit 220 refers to the table stored in the ROM and derives the toner flow rate from the resistance value read from the conductive layer.

  The control unit controls the operation of each unit of the image forming apparatus 100 based on the toner flow velocity obtained by the calculation of the calculation unit 220. For example, when the flow rate of the toner calculated by the calculation unit 220 decreases and becomes less than a predetermined threshold, the control unit replaces the toner container 32 with a liquid crystal panel (notification unit) provided in the image forming apparatus 100. Control is performed to display a message for prompting replacement of other parts. In this case, the ROM stores a table that evaluates how many output sheets can cause the toner clogging with respect to the amount of decrease in the flow rate, and the control unit refers to the table based on the amount of decrease in the flow rate. Thus, various messages can be displayed on the liquid crystal panel at an appropriate timing. The notification means for notifying the outside that various messages and errors have occurred may be a speaker that performs sound notification, a lamp that performs light notification, or the like.

[Second Embodiment]
A flow velocity measuring apparatus according to a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a schematic diagram showing a flow velocity measuring device according to the second embodiment. The flow velocity measuring apparatus according to the present embodiment measures the toner flow velocity by vibrating the cantilever and detecting a change in amplitude or frequency of the cantilever.
The flow velocity measuring apparatus 200 includes an oscillating means (vibrating means) that oscillates (vibrates) the cantilever 213 at a predetermined frequency and amplitude. The oscillating means includes an oscillating piezoresistor 231 disposed at the fixed side end of the cantilever 213 and an oscillating circuit 233 that drives the oscillating piezoresistor 231.
The oscillation method of the cantilever 213 is the same as that of a general atomic force microscope. The cantilever 213 is oscillated by applying a predetermined voltage to the oscillating piezoresistor 231 installed at the fixed side end of the cantilever 213 to periodically expand and contract.

The arithmetic unit 220 detects a change in the amplitude of the cantilever 213 as a change in the resistance value of the piezoresistor 211. The calculation unit 220 may include a frequency measurement circuit such as a pulse counter for measuring the number of changes in the amplitude of the cantilever 213 per unit time, in other words, a change in frequency. As described above, the calculation unit 220 calculates the toner flow velocity based on the change in the amplitude or the frequency of the cantilever 213 due to the contact of the toner.
In the present embodiment, since the oscillation means is provided to oscillate the cantilever 213, the cost increases. However, the toner flow rate is measured more than the method of detecting the warp generated in the stationary cantilever 213 (first embodiment). Sensitivity can be improved. Accordingly, it is possible to improve the accuracy of toner clogging prediction in the toner drop conveyance path 64.

[Third embodiment]
A flow velocity measuring apparatus according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a partially enlarged view of the transport nozzle and the toner dropping transport path shown in FIG.
As shown in FIG. 4, it is also effective to use a sensor unit 210 having an array structure in which cantilevers 213 are arranged in a one-dimensional array. In FIG. 4, a plurality of cantilevers 213 are arranged in an array in a direction that intersects the powder conveyance direction. With the sensor unit 210 having an array structure, even when some of the cantilevers 213 are damaged or performance is deteriorated, the flow rate of the toner can be continuously detected using other normal cantilevers.
Further, since the sensor unit 210 has an array structure, even if there is a gradient of the amount of toner to be transported in the cross section of the toner dropping transport path 64 in the direction perpendicular to the transport direction (in the transport path cross section), It is possible to accurately measure the flow rate of the toner including the difference in the amount.

Specifically, as shown in FIG. 7, in the cross section of the toner dropping conveyance path 64, the amount of toner conveyed is relatively large at the opening side end of the conveyance nozzle 61, but from the opening end of the conveyance nozzle 61. There is a tendency that the amount of toner transported is relatively small in the separated portions.
In such a case, a sensor unit 210 in which a plurality of cantilevers 213 are arranged in parallel along the longitudinal direction of the support member 215 is prepared, and the longitudinal direction of the support member 215 is a direction with a gradient of toner amount (in FIG. 7). (Arranged in the horizontal direction). As described above, even when there is a gradient of the toner amount in the cross section in the replenishment path, the flow rate of the toner can be accurately measured by using the sensor unit having the array structure as shown in FIG.

[Fourth embodiment]
A flow velocity measuring apparatus according to the fourth embodiment of the present invention will be described. The present embodiment is characterized in that the surface of the cantilever is coated with a water repellent material.
As described above, the sensor unit 210 of the flow velocity measuring device 200 is disposed in the toner dropping conveyance path 64. For this reason, the cantilever 213 always keeps contact with the toner, and the surface of the cantilever 213 is in a state where it is easily contaminated by the toner. If the surface of the cantilever 213 is excessively contaminated with toner, the cantilever 213 is difficult to bend, and the measurement sensitivity of the toner flow rate is lowered.
Therefore, in the present embodiment, the surface of the cantilever 213 is coated with a water repellent material such as a fluorine-based material to prevent the toner from adhering to the surface of the cantilever 213, and the measurement sensitivity of the toner flow rate stable over time is maintained.

[Fifth embodiment]
A flow velocity measuring apparatus according to the fifth embodiment of the present invention will be described. FIG. 8 is a partially enlarged view of the transport nozzle and the toner dropping transport path shown in FIG. The present embodiment is characterized in that a plurality of sensor units are arranged along the toner conveyance direction.
The flow velocity measuring device 200 includes a first sensor unit 210a disposed in the toner drop conveyance path 64 and a second sensor unit 210b disposed on the downstream side in the toner conveyance direction from the first sensor unit 210a. The first sensor unit 210a and the second sensor unit 210b can be the sensor units shown in the first to fourth embodiments, and each includes one or more cantilevers 213. That is, in the flow velocity measuring apparatus 200 according to the present embodiment, a plurality of cantilevers 213 are arranged with different positions in the toner conveyance direction.
By disposing a plurality of cantilevers 213 in different positions in the toner conveyance direction, even if some of the cantilevers 213 are damaged or performance is deteriorated, the flow rate of toner is continuously increased using other normal cantilevers. Can continue to be detected.
If there is a gradient in the amount of toner transported in the cross section of the toner dropping transport path 64, even if a plurality of cantilevers are installed at the same position in the transport direction as in the third embodiment, Therefore, it is necessary to arrange a plurality of cantilevers along the toner conveyance direction.

[Example Embodiments and Effects]
The present invention can be carried out in the following modes <First embodiment>
The present embodiment is a flow velocity measuring apparatus 200 that measures the flow velocity of powder (toner) conveyed in a predetermined direction in the conveyance path (in the toner dropping conveyance path 64), and a part thereof is a support means (support member 215). ) And a cantilever 213 provided with a piezoresistor 211 that outputs the deformation of the beam portion due to the contact of the conveyed powder as an electrical resistance value. And a calculation means (calculation unit 220) for deriving the flow velocity of the powder based on the resistance value output from the piezoresistor.

In recent years, the toner fixing temperature tends to decrease, and accordingly, the fluidity of the toner tends to deteriorate. As a result, toner clogging is likely to occur in the toner transport path for transporting toner from the toner container to the developing device. When toner is clogged in the toner conveyance path, there is a problem that it takes time to recover because replacement of parts by a specialized service person is necessary. When toner is clogged in the toner conveyance path, a decrease in the toner flow rate in the toner conveyance path is recognized as a sign of this, and a means for detecting this is required.
As a method for detecting toner in the toner conveyance path, there is a method in which a piezoelectric vibrator or an ultrasonic sensor is installed on the inner wall of the conveyance path. With this method, the presence or absence of toner near the sensor can be detected, but the amount of toner inflow per unit time cannot be detected.

In the flow velocity measuring apparatus according to this embodiment, a cantilever having a piezoresistor is disposed in the transport path. Since the cantilever bends when the toner is conveyed, the toner conveyance amount can be measured from the amount of the deflection. Since the flow rate of the toner in the conveyance path can be measured, it is possible to grasp in advance whether there is a possibility that the toner is clogged in the toner conveyance path. Since necessary measures such as replacement of parts can be taken before toner is clogged in the conveyance path, downtime of the image forming apparatus can be minimized.
Moreover, the cantilever which comprises the sensor part of this embodiment is a micro scale component which can be created by MEMS technology. The size of the sensor unit, including other wiring and installation mechanisms, can be made very small, so that there is almost no space for installing sensors around the transport path with a small transport path like the toner transport path. The sensor unit can be installed even in difficult situations. Furthermore, since the cantilever is of a built-in piezo type, an optical system for detecting the displacement of the cantilever is not required, so that the total system can be made very compact.

<Second embodiment>
The flow velocity measuring apparatus 200 according to the present embodiment includes vibration means (oscillation piezoresistor 231 and oscillation circuit 233) for vibrating the beam portion 214 at a predetermined frequency and amplitude, and the calculation means (calculation unit 220) is transported. The flow rate of the powder is derived on the basis of a change in the frequency or amplitude of the beam portion due to the contact of the powder (toner).
The measurement sensitivity is improved by detecting the frequency or amplitude that changes due to the bending of the vibrating cantilever rather than detecting the bending of the stationary cantilever. For example, when the sensor unit of the flow velocity measuring device according to this embodiment is disposed in the toner conveyance path of the image forming apparatus, the toner flow velocity measurement sensitivity can be improved. Therefore, the prediction accuracy of toner clogging in the toner conveyance path is also improved.

<Third embodiment>
The flow velocity measuring apparatus 200 according to this embodiment is characterized in that a plurality of cantilevers 213 are arranged in an array in a direction intersecting with the powder (toner) conveyance direction.

Since the flow velocity measuring device 200 includes a plurality of cantilevers, even if one cantilever fails, the flow velocity of the powder can be measured as long as other cantilevers are operating.
Here, if there is a gradient in the amount of powder transport in the cross section of the transport path in the direction perpendicular to the transport direction, even if a single cantilever is installed in the transport path, the entire toner transport state in the transport path I can't figure out. According to this aspect, since the plurality of cantilevers are arranged in an array in the direction intersecting the transport direction, the toner flow velocity distribution in the cross section of the transport path can be measured. Therefore, even when there is a gradient of the amount of powder transport in the cross section of the transport path, the transport state of the powder in the entire transport path can be grasped.

<Fourth embodiment>
The flow velocity measuring apparatus 200 according to this embodiment is characterized in that the surface of the cantilever 213 is coated with a water repellent material.
Since the cantilever arranged in the conveyance path continues to come into contact with the powder, the surface is contaminated and the measurement sensitivity of the flow velocity is lowered. In this embodiment, since the surface of the cantilever is water-repellently coated, the powder hardly adheres to the cantilever, and stable measurement performance can be maintained over time.

<Fifth embodiment>
The flow velocity measuring apparatus 200 according to the present embodiment is characterized in that a plurality of cantilevers 213 are arranged along the conveying direction of the powder (toner).
Since the flow velocity measuring device 200 includes a plurality of cantilevers, even if one cantilever fails, the flow velocity of the powder can be measured if the other cantilevers are operating.
Note that if there is a gradient of the powder conveyance amount in the cross section of the conveyance path in the direction perpendicular to the conveyance direction, even if a plurality of cantilevers are arranged in the same cross section, the toner amount gradient in the cross section is measured. Will do. In this case, for example, in order for two cantilevers to detect the same toner conveyance amount, it is necessary to install cantilevers at two locations where the positions in the toner conveyance direction are different and the toner conveyance amounts are the same.

<Sixth and seventh embodiments>
The image forming apparatus 100 according to the sixth embodiment includes a transport path (toner dropping transport path 64) for transporting toner as powder, and a flow rate measuring apparatus 200 for measuring the flow speed of toner transported in the transport path. And forming an image by an electrophotographic method.
The image forming apparatus 100 according to the seventh embodiment notifies a predetermined message to the outside when the flow rate of the powder (toner) derived by the calculation unit (calculation unit 220) is less than a predetermined threshold value. An informing means (liquid crystal panel or the like) is provided.
Since the flow velocity measuring device 200 can accurately detect a decrease in toner fluidity, it is possible to notify the user or service person of the replacement timing of the toner or various components at an appropriate timing.

  DESCRIPTION OF SYMBOLS 100 ... Image forming apparatus, 1 ... Photosensitive drum, 6 ... Image forming unit, 7 ... Optical writing unit, 8 ... Intermediate transfer belt, 9 ... Primary transfer roller, 10 ... Intermediate transfer cleaning apparatus, 12 ... Secondary transfer backup Roller, 15 ... primary transfer unit, 16 ... secondary transfer unit, 18 ... duplex unit, 19 ... secondary transfer roller, 20 ... fixing unit, 26a ... paper feed cassette, 26b ... manual feed tray, 27a ... paper feed roller, 27b ... Paper feeding roller, 28 ... Registration roller pair, 29 ... Discharge roller pair, 30 ... Stack part, 31 ... Toner container housing part, 32 ... Toner container, 33 ... Container body, 34 ... Container tip side cover, 35 ... Container Gears 36... Agitator 50. Developing device 56. Toner density detection sensor 60. Toner replenishing device 61 61 Conveying nozzle 62 62 Conveying screw 6 DESCRIPTION OF SYMBOLS ... Conveyance screw gear, 64 ... Toner fall conveyance path, 90 ... Control part, 91 ... Rotation drive part, 200 ... Flow velocity measuring device, 210 ... Sensor part, 210a ... First sensor part, 210b ... Second sensor part, 211 ... Piezo Resistor, 213... Cantilever, 214... Beam part, 215. Support member, 220. , 706 ... connecting part, 722, 724 ... piezoresistor, 726, 728, 732, 734 ... conductive layer, 736, 738, 742, 744 ... metal contact part

Japanese Patent No. 2887256

The Electrophotographic Society of Japan "Basics and Applications of Electrophotographic Technology", Corona, June 15, 1988, pp. 296-297

Claims (6)

A flow velocity measuring device for measuring a flow velocity of powder conveyed in a predetermined direction in a conveyance path,
A beam portion that is partially supported by a support means and disposed in the transfer path, and a piezoresistor that outputs deformation of the beam portion due to contact of the transferred powder as an electrical resistance value. Cantilevers,
Vibration means for vibrating the beam portion at a predetermined frequency and amplitude;
A flow velocity measuring device comprising: a calculating means for deriving a flow velocity of the powder based on a change in frequency or amplitude of the beam portion detected as a change in resistance value output from the piezoresistor. . The flow velocity measuring device according to claim 1 , wherein the plurality of cantilevers are arranged in an array in a direction intersecting with the conveying direction of the powder. The flow velocity measuring device according to claim 1 or 2 , wherein a surface of the cantilever is coated with a water repellent material. The flow velocity measuring device according to any one of claims 1 to 3 , wherein a plurality of the cantilevers are arranged along a conveyance direction of the powder. And the transport path for transporting the toner as the powder, and a flow rate measuring device according to any one of claims 1 to 4 for measuring the flow rate of the toner to be conveyed to the conveying path, the electronic An image forming apparatus for forming an image by a photographic method. The image forming apparatus according to claim 5 , further comprising a notifying unit that notifies a predetermined message to the outside when the flow velocity of the powder derived by the calculating unit is less than a predetermined threshold value. .

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