JP2011227202A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize steady feeding of a developer to a development processor, and accordingly form a good visual image, without being affected by the environment of use, the remaining quality of the developer in the storage vessel thereof and the duration of the developer being let stand, and to prevent flashing within an imaging apparatus.SOLUTION: A hopper section 7 temporarily holds a toner (developer) fed from a toner bottle (developer storage vessel) 6 detachable from an imaging apparatus body and containing the toner, and feeds the same to a development processor. In the hopper section 7, a toner sensor 19 that detects the toner in the hopper section is arranged. When feeding the hopper section 7 from the toner bottle 6, the feeding action of the toner bottle 6 by a developer storage vessel driving means is altered on the basis of the output value of the toner sensor 19 within a predetermined length of time during the feed. For instance, the rotating speed (and the developing bias) of the tonner bottle is altered on the basis of this toner feed quantity.

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a facsimile machine, and a printer that forms an electrostatic image on an image carrier and forms a visible image by developing the electrostatic image with a developer (toner). . In particular, the present invention relates to an image forming apparatus that supplies a developer in a developer storage container to a developing device via a toner replenishing unit called a hopper unit.

  In recent years, the size of such an image forming apparatus has been reduced, and the developing device has also been reduced in size, so that the toner storage capacity in the developing device has been reduced. When a plurality of developing devices are provided, they must be accommodated in a limited space around the electrostatic latent image carrier.

  Therefore, there is an image forming apparatus that replenishes toner directly from a developer storage container (hereinafter referred to as a toner bottle) filled with toner to a developing device. In this configuration, since the amount of toner discharged into the developing device is not constant depending on the remaining amount of toner in the toner bottle, the ratio of new / old toner in the developing device may become non-uniform, resulting in poor image quality.

  On the other hand, a hopper portion for temporarily storing toner is provided between the toner bottle and the developing device, and a developer replenishing device that stably supplies toner by supplying toner to the developing device via the hopper portion is provided. There is an image forming apparatus (see Patent Document 1).

  More specifically, toner is discharged from the discharge opening of the toner bottle by rotating a toner bottle having a spiral protrusion on the inner peripheral surface at a constant rotation speed with the central axis as the rotation center. The discharged toner is temporarily received in, for example, a hopper provided at a lower portion of a developer replenishing device (hereinafter referred to as a toner replenishing device), and the toner in the hopper is conveyed toward the developing device. ing.

  When the amount of toner in the hopper is less than the reference amount, the rotation drive mechanism is driven based on the replenishment command signal to start rotation of the toner bottle. As a result, the toner contained in the toner bottle is discharged. On the other hand, when the amount of toner in the hopper portion exceeds the reference amount, the rotation driving mechanism is stopped based on the replenishment stop signal, and the rotation of the toner bottle is stopped.

  As described above, according to the toner replenishing device, the toner bottle is rotated as necessary to supply the toner to the hopper, and thereby the toner is replenished to the developing device.

Japanese Patent Laying-Open No. 2005-084072

  In the above toner replenishing device, when the amount of residual toner in the toner bottle is large, the amount of toner discharged from the toner bottle is also very large, so the connection between the toner bottle and the hopper, or between the hopper and the developing unit, respectively There is a possibility that toner blows out (hereinafter referred to as flushing) at the portion, and the toner is scattered in the image forming apparatus. When the scattered toner adheres to the paper (media) transport unit inside the image forming apparatus, there arises a problem that the output paper transported through that portion becomes dirty.

  Further, as the amount of toner remaining in the toner bottle decreases, the amount of toner discharged in one rotation decreases, so the toner supply speed to the hopper is reduced. As a result, when the remaining amount of toner is small, it is necessary to rotate the toner bottle more until the amount of toner in the hopper reaches the reference amount after the replenishment command signal is issued. Therefore, a long time is required for one toner supply.

  For example, in the case where images with a high printing rate (for example, more than 70%) are continuously formed as a visible image, a large amount of toner is rapidly consumed in a short time in the developing device. Supply will be insufficient. As a result, the amount of toner in the hopper is reduced, and the supply of toner from the hopper to the developing device becomes insufficient.

  As described above, the conventional toner replenishing device cannot stably replenish the toner to the developing unit, and a phenomenon such as a local decrease in image density occurs and a good visible image cannot be obtained. was there. In addition, although there is toner in the toner bottle, there is a problem that the toner in the developing device cannot be supplied in time and the toner bottle is detected as having no toner.

  The remaining amount of toner in the toner bottle can also be detected by installing a printing rate counter, a non-volatile memory for storing consumption, and a bottle toner sensor, but this leads to an increase in the size and cost of the device. It was.

  Furthermore, even if the amount of toner remaining in the toner bottle is found, and even if the toner weight in the toner bottle is the same, the fluidity of the toner changes depending on the usage environment and the toner bottle leaving time. Therefore, there has been a problem that the toner supply amount is not constant.

  The present invention has been made in view of such problems, and the object thereof is to supply the developer to the developing device regardless of the use environment, the remaining amount of developer in the developer storage container, and the standing time. It is an object of the present invention to provide an image forming apparatus capable of stably performing the above-described process, and thus forming a good visible image and preventing flashing in the image forming apparatus.

  An image forming apparatus according to the present invention is an image forming apparatus provided with a developing unit that visualizes an electrostatic latent image formed on an image carrier with a developer. The image forming apparatus accommodates the developer and is detachable from the image forming apparatus main body. Provided in the developer replenishment path of the hopper part, which temporarily stores the developer supplied from the developer storage container and passes the hopper part supplied to the developing unit, and the developer supplied into the hopper part. Developer detecting means for detecting the supplied developer, and developer storage container driving means for causing the developer storage container to perform a supply operation and supplying the developer from the developer storage container into the hopper. When the replenishment from the developer storage container to the hopper is performed, the development by the developer storage container driving unit is performed based on the output value of the developer detection unit within a predetermined time during replenishment. Characterized by comprising a developer supply control means for changing the supply operation of the storage vessel.

  In this configuration, when replenishing from the developer storage container to the hopper, the developer is replenished in a relatively short predetermined time, and the actual replenishment amount within the predetermined time at that time is confirmed. Based on the replenishment amount thus confirmed, the replenishment flow rate (that is, the replenishment amount within a unit time) can be increased or decreased in subsequent replenishment operations.

  The developer supply control means, for example, based on an integrated value obtained by integrating the change in the output value of the developer detecting means within the predetermined time during the replenishment within the predetermined time. Then, the replenishment amount of the developer is determined. More specifically, the developer supply control means detects the developer by the developer detection means in a unit time period within the predetermined time, and adds the detection output value within the predetermined time. The replenishment amount can be obtained based on the above.

  The developer supply control means controls the developer storage container driving means according to the determined supply amount so that the developer supply amount from the developer storage container within a unit time becomes a predetermined amount. Can do. For example, the developer storage container has a spiral protrusion on the inner wall circumferential surface thereof, and the developer storage container driving means rotates the developer storage container to guide the protrusion to the developer. The developer can be discharged to the outside as a unit, and the developer supply control means can control the rotation speed of the developer storage container. By changing the rotation speed, the amount of developer discharged from the developer storage container per unit time can be increased or decreased.

  In this case, an AC voltage applying means for applying an AC voltage (developing bias AC component) to the developing device to cause the developer to fly on the image carrier, and the rotation speed of the developer storage container AC voltage control means for controlling the amplitude (Vpp) of the AC voltage may be provided. Thereby, the influence of the damage of the developer when the rotation speed is high is reduced.

  The developer detection means includes, for example, a sensor that detects the amount of developer present in the detection region, and the sensor is provided almost directly below the opening of the developer storage container that discharges the developer. .

  The hopper may have a developer supply path through which the developer discharged from the opening of the developer storage container passes. In this case, the sensor is arranged facing the developer supply path.

  The developer replenishing path may have an inner wall formed in the hopper portion. Due to the action of the inner wall, the developer is easily detected by the developer detecting means.

  The developer replenishment path may have a cylindrical shape formed in the hopper portion. Due to the action of the cylinder, the developer is easily detected by the developer detecting means.

  The developer replenishing path may have an inclined surface on which the developer discharged from the opening of the developer storage container slides. Thereby, the effect that the supplied developer approaches the developer detecting means is expected.

  According to the image forming apparatus of the present invention, the actual developer replenishment amount can be confirmed regardless of the use environment, the developer remaining amount in the developer storage container, and the developer storage container standing time. As a result, the developer replenishment flow rate can be adjusted (fixed), so that the developer replenishment device can rapidly and stably replenish the developer. As a result, it is possible to always form a good visible image.

It is explanatory drawing which shows an example of a structure of the image forming apparatus of this invention. FIG. 2 is an enlarged cross-sectional explanatory view (a) showing a main part of the image forming apparatus shown in FIG. 1 and an explanatory view (b) viewed from the lateral direction. It is explanatory drawing about the magnetic bridge sensor used as a toner sensor in embodiment of this invention. 6 is a graph showing a relationship between a toner remaining amount and an analog detection signal of a toner sensor by a magnetic bridge sensor. FIG. 6 is an explanatory diagram of a developer detection unit that detects toner discharged from a toner bottle. 6 is a graph in which output voltage values induced in a magnetic bridge sensor are plotted every 1 msec when toner is supplied at a full toner supply flow rate for a predetermined time when the toner amount of the toner bottle is full. It is explanatory drawing of the method of approximating the integral value of the graph of FIG. FIG. 7 is a diagram illustrating a model for discharging toner from a toner bottle when the toner having the same cohesion degree as in the example illustrated in FIG. 6 is used and the amount of toner in the toner bottle is small. 6 is a graph plotting output voltage values induced in a magnetic bridge sensor every 1 msec when toner is supplied for 1 second when the toner supply flow rate is relatively small. It is explanatory drawing of the method of approximating the integral value of the graph of FIG. FIG. 10 is a diagram showing the correlation between the integrated values of the graphs of FIGS. 6 and 9 and the relationship between the toner supply flow rate from the toner bottle at that time. It is a figure which shows the structural example of the control data table which can be used in embodiment of this invention. It is a flowchart which shows the specific process flow of the main processes in embodiment of this invention. It is a flowchart which shows the specific process flow of the main process in this Embodiment in the case of performing 2nd control in addition to 1st control. It is a figure which shows the modification of a structure of the hopper part in embodiment of this invention. It is a figure which shows another modification of the structure of the hopper part in embodiment of this invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram showing an example of the configuration of the image forming apparatus of the present invention.

  The image forming apparatus mainly includes a photosensitive drum 1, a charging unit 2, a developing unit 3, a transfer unit 4, a fixing unit 5, a toner replenishing device 8, a recovery mechanism A, an image exposure unit B, a control unit C, and a high pressure generation unit. D is provided.

  The photosensitive drum 1 is an image carrier having a photosensitive layer such as an organic photoreceptor. The charging unit 2 is charging means for uniformly charging the photosensitive drum 1 to a predetermined potential by a charging member such as a charging roller. The image exposure unit B emits, for example, a laser beam to the uniformly charged photosensitive drum 1 based on image information of an image reading unit (not shown), and a polygon mirror (not shown) and a reflection mirror (not shown). An exposure unit such as a laser scanner that forms an electrostatic charge image on the photosensitive drum 1 by exposing the photosensitive drum 1 through a not-shown).

  The developing unit 3 is a developing unit that develops (visualizes) a toner image by developing the electrostatic image formed on the photosensitive drum 1 by causing the toner to fly to the photosensitive drum 1. The transfer unit 4 is a transfer unit that transfers the toner image formed on the photosensitive drum 1 onto a transfer material such as paper. The fixing device 5 is a fixing unit that fixes the toner image transferred onto the surface of the transfer material with heat or the like.

  The collection mechanism A is a cleaning unit (collection unit) that collects residual toner that is not transferred onto the transfer material and remains on the photosensitive drum 1.

  The high pressure generator D is a part that generates a high pressure necessary for operations such as charging, developing, and transfer of the photosensitive drum 1.

  The control unit C is a control unit that controls the entire image forming apparatus, and includes a CPU, a memory, and the like.

  As will be described later, the toner replenishing device 8 temporarily stores toner supplied from a toner bottle (developer storage container) that is detachable from the main body of the image forming apparatus, and supplies the toner to the developing device. A toner sensor (described later) is provided as toner detecting means for detecting toner in the unit.

  When replenishing the toner bottle from the toner bottle to the hopper (described later in FIG. 2), the control unit C receives a toner detection signal obtained from the toner sensor, and determines a predetermined value during replenishment (for example, at the start of replenishment). Developer supply control means for changing the toner bottle supply operation by the developer storage container driving means based on the output value of the toner sensor within the time is also constituted. The developer supply control means is configured to provide a toner within a predetermined time based on an integral value obtained by integrating a change in the output value of the toner sensor within a predetermined time during the replenishment within a predetermined time. Determine the replenishment amount. The toner replenishment amount within a predetermined time can be converted into a toner replenishment amount (that is, a toner replenishment flow rate) within a unit time, as shown in FIGS.

  The control unit C also constitutes a developer storage container driving unit that causes the developer storage container to perform a supply operation and supplies toner from the developer storage container into the hopper. The storage container drive means is controlled so that the toner replenishment amount from the toner bottle within a unit time becomes a predetermined amount according to the determined replenishment amount.

  The high voltage generator D constitutes an AC voltage applying unit that applies an AC voltage (developing bias AC component) to the developing device in order to cause the toner to fly on the photosensitive drum 1.

  The controller C also constitutes AC voltage control means for controlling the amplitude (Vpp) of AC voltage according to the rotational speed of the developer storage container and processing means for executing necessary processing.

  The operation of the image forming apparatus having the above configuration is as follows.

  For example, in an example of a copying machine, when an image is formed, an image of a document is read by an image reading unit (not shown) to obtain image information. Based on this image information, the photosensitive drum 1 is exposed by the image exposure section B, whereby an electrostatic charge image is formed on the photosensitive drum 1. Further, the electrostatic image formed on the photosensitive drum 1 is developed by the developing device 3, whereby a toner image is formed on the surface of the photosensitive drum 1. The toner image is transferred to the conveyed paper in the transfer unit 4. Thereafter, the paper separated from the photosensitive drum 1 is conveyed toward the fixing device 5. In the fixing device 5, the toner image is fixed on the paper by, for example, heat and pressure. In this way, a visible image corresponding to the original image is fixedly formed on the paper. The paper on which the visible image is formed is discharged from the fixing device 5 and then conveyed and discharged to the outside through a transfer material discharge port (not shown).

  Further, the toner remaining on the surface of the photosensitive drum 1 after the paper is separated is removed by passing through the cleaning unit A.

  In the case of a printer or facsimile, image information is received from the outside instead of reading a document.

  FIG. 2 is an enlarged sectional explanatory view (a) showing the toner bottle 6, the developing device 3, and the toner replenishing device 8 with the toner bottle 6 attached, and an explanatory view seen from the lateral direction (b). ).

  A hopper portion 7 is provided above the developing unit 3. As described above, the hopper unit 7 is means for temporarily storing the toner supplied from the toner bottle 6 detachably attached to the image forming apparatus main body and supplying the toner to the developing device. The hopper unit 7 includes a toner transport mechanism that transports the toner inside to the developing device 3. In this example, the toner transport mechanism includes a rotational drive mechanism 15 such as a motor, and a toner transport screw 13 that is rotationally driven by the rotational drive mechanism 15.

  As often shown in FIG. 2B, the toner replenishing device 8 includes a toner bottle 6 having a central axis L arranged in the horizontal direction, and a toner bottle mounting portion 9 that rotatably supports the toner bottle 6. And a rotation driving mechanism 10 that rotates the toner bottle 6 by rotation driving, such as a motor. In the toner replenishing device 8, the toner bottle 6 can be attached to and detached from the toner bottle mounting portion 9.

  In the toner bottle 6, a spiral protrusion 6 </ b> A is formed on the inner wall peripheral surface of a cylindrical container containing toner therein so as to protrude inward of the container. The protrusion 6A forms a toner guide portion. A discharge opening (developer discharge portion) 6C through which the toner guided by the toner guide portion is discharged is formed in the front end portion 6B located on one end side of the toner bottle 6. Further, the toner bottle 6 is provided with a slide lid 6D on one end side thereof. The slide lid 6D is a lid that is movable in the left-right direction in FIG. 2B so as to open and close the discharge opening 6C of the toner bottle 6. When the toner bottle 6 is mounted on the toner bottle mounting portion 9, the slide lid 6D holds the discharge opening 6C in an open state.

  The hopper portion 7 has a toner storage portion that is hung downward from substantially the same height in the horizontal direction of the discharge opening 6C in the toner bottle mounting portion 9, and receives the toner discharged through the discharge opening 6C of the toner bottle 6. To do. The purpose is to form a flat interface between the toner in the hopper 7 as much as possible in the horizontal direction (left and right in FIG. 2B), or to improve the fluidity of the toner in the hopper 7. In the hopper part 7, the hopper stirrer 11 is arranged. The toner in the hopper 7 is stirred by the hopper stirrer 11. Further, with this agitation, the toner in the hopper 7 is discharged to the toner supply port 12 of the hopper 7.

  Due to the stirring by the stirrer 11 and the influence of gravity, the toner transported to the toner supply port 12 is transported from the hopper 7 to the developing device 3 by the toner transport mechanism including the rotation drive mechanism 15 and the toner transport screw 13 described above. Is done. That is, the toner that has passed through the toner supply port 12 is transported toward the developing device supply port 17 by the rotation of the transport screw 13, and is supplied to the developing device 3 through the developing device supply port 17.

  The hopper portion 7 is provided with a toner sensor 14 (developer remaining amount detecting means) for detecting the amount of toner remaining in the hopper portion 7. The toner sensor 14 is for issuing a replenishment command signal and a replenishment stop signal to the developing device 3 based on the amount of toner in the hopper 7 and can be constituted by a magnetic permeability sensor, for example. That is, when the amount of toner in the hopper 7 detected by the toner sensor 14 is smaller than the reference amount, a replenishment command signal is issued. Further, upon receiving this replenishment command signal, the drive source in the rotary drive mechanism 10 is driven, and the toner bottle 6 is rotated as the drive shaft rotates.

  In the toner bottle 6 rotated by the rotation driving mechanism 10, the toner contained in the toner bottle 6 is scraped up and dropped by the toner guide portion constituted by the spiral protrusion 6A while being repeatedly discharged. Guided towards. The toner is discharged to the hopper portion 7 through the discharge opening 6C.

  Normally, when the image forming operation is performed, the toner of the developing device 3 is consumed, and when the remaining amount of toner becomes a predetermined value or less, the toner sensor 16 on the developing device 3 detects the absence of toner. At that time, if the toner sensor 14 in the hopper 7 detects the presence of toner, the toner supply command to the developing device 3 is issued to the hopper 7, and the agitator 11 in the hopper 7 and the toner The conveying screw 13 is rotated to supply toner to the developing device 3.

  Even if the toner sensor 14 in the hopper 7 detects the absence of toner due to the supply of toner to the developing device 3, if the toner sensor 16 in the developing device 3 detects the presence of toner, the normal image operation is affected. Therefore, the image forming operation is not stopped.

  However, when both the toner sensor 14 in the hopper 7 and the toner sensor 16 in the developing device 3 detect the absence of toner, the image forming operation is stopped and the toner supply from the toner bottle 6 to the hopper 7 is started. To do.

  The toner replenishing device 8 is provided with the rotation drive mechanism 10 described above, and the toner bottle 6 is rotated by the rotation drive mechanism 10 rotating. As a result, the toner is discharged from the toner bottle 6 to the hopper unit 7. For example, the toner discharge amount (toner discharge amount per unit time, that is, the toner replenishment flow rate) discharged by rotating the toner bottle 6 with the rotation of the rotation drive mechanism 10 for a certain period of time is the remaining toner amount in the toner bottle 6. Is generally correlated. That is, when toner remains in the toner bottle 6 in a large amount, the toner is filled up to the vicinity of the toner bottle discharge opening 6C provided in the toner bottle 6, so that a large amount of toner can be obtained in a relatively short time. Is discharged. On the other hand, when the amount of toner in the toner bottle 6 is small, the toner does not reach the toner bottle discharge opening 6C, and it takes a long time to discharge, for example, a small amount of 30 g of toner.

  When the toner bottle is rotated at a constant speed regardless of whether the toner remaining amount in the toner bottle is large or small, the above-mentioned flushing occurs when the toner remaining amount in the toner bottle is large, and toner replenishment occurs when the toner amount is small. The problem of taking a long time occurs.

  As described above, conventionally, it is common to detect the toner weight in the toner bottle and change the rotation speed of the toner bottle based on the weight.

  However, the toner weight is not necessarily correlated with the toner replenishment flow rate discharged from the toner bottle. For example, the toner cohesion degree in a toner bottle left in a high temperature and high humidity environment for a long time is very high, and even if a lot of toner is filled in the toner bottle, the toner fluidity is low. The replenishment flow rate is lower than usual. For this reason, in the sequence in which the rotation speed of the toner bottle is changed based on the toner weight in the toner bottle, the above-described problems have occurred.

  Therefore, in the present embodiment, the toner supply amount from the toner bottle within the predetermined time is actually accurately detected, and the toner bottle rotation speed is optimized to speed up and stabilize the toner supply. To do.

  With reference to FIG. 3, the magnetic bridge sensor 20 used as a toner sensor (permeability sensor) in the present embodiment will be described.

  In the example of FIG. 3, the magnetic bridge sensor 20 is integrally configured in a shape in which an elliptical cylindrical detection head 20b is mounted on a substantially rectangular plate-shaped main body 20a, and an input / output signal line 20c. The detection signal is exchanged with the image forming apparatus main body via the.

  A detection transformer is embedded in the detection head 20b. This detection transformer is composed of a total of three windings (coils), one primary winding, and two secondary windings composed of a reference winding and a detection winding. The detection winding is positioned on the top side of the detection head 20b, and the reference winding is positioned on the back side of the detection head 20b with the primary winding interposed therebetween.

  When a current having a signal having a constant waveform is input to the primary winding from an oscillator provided in the main body 20a of the magnetic bridge sensor 20, the two secondary windings including the reference winding and the detection winding are also input to the primary winding. A current having a signal with a certain waveform flows by electromagnetic induction. The detection head 20b is determined by determining a signal having a constant waveform from the oscillator at this time and a signal having a certain waveform of a current flowing from the detection winding by electromagnetic induction by a comparison circuit provided in the sensor body 20a. The density of the magnetic material is detected on the top surface side of the. In other words, different outputs can be obtained depending on the amount of magnetic material before and after the detection head 20b.

  The magnetic bridge sensor 20 is provided with a ferrite screw core movably provided at the center of the detection transformer in order to cope with differences in magnetic density and the like of the magnetic material to be detected, and adjusts the position of the screw core. Therefore, proper detection is possible.

  Next, the toner sensor 14 as a developer remaining amount detection unit will be described. The toner sensor 14 detects the remaining amount of toner stored in the hopper 7 by the magnetic bridge sensor 20. The detection range of the detection head 20b of the magnetic bridge sensor 20 is set to be larger than the range from when the toner is fully charged until it becomes empty.

  FIG. 4 is a graph showing the relationship between the remaining amount of toner and the analog detection signal of the toner sensor 14 by the magnetic bridge sensor 20.

  As can be seen from this graph, the magnetic bridge sensor 20 shows the highest output voltage when the toner remaining amount in the hopper 7 is full (when full), and the highest when the toner remaining amount is empty (when empty). Indicates low output voltage. For the remaining toner amount between maximum filling and empty, the output voltage corresponds to the remaining toner amount on a one-to-one basis, and the relationship between the output voltage and the remaining toner amount is expressed by a one-to-one correspondence line or curve. An output voltage corresponding to the amount can be obtained. Further, when the detected remaining amount of toner becomes less than a predetermined amount of remaining toner, it is determined that the toner needs to be replenished into the hopper unit 7 and the toner is supplied from the toner bottle 6.

  Next, the detection developer detecting means for detecting the toner discharged from the toner bottle 6 will be described with reference to FIG.

  First, the toner sensor 19 is disposed vertically below the toner bottle opening as a developer detecting means. This toner sensor is a sensor that detects the amount of toner present in the detection region. As the toner sensor 19, the magnetic bridge sensor 20 can be used. The developer detecting means can be realized by the toner sensor 19 and processing means for processing the output. The control unit C can also serve as this processing means. The toner sensor 19 can also function as the toner sensor 14.

  The hopper portion 7 has a toner supply path (developer supply path) through which the toner discharged from the toner bottle opening passes. The toner sensor 19 is disposed facing the toner supply path. In the example of FIG. 5, it is installed on the wall surface (side outer wall) of the hopper portion 7. Moreover, the inner wall 22 which opposes this side surface outer wall is provided. The inner wall 22 is for making it easy for the toner replenished from the toner bottle 6 to the hopper portion 7 to pass through the front surface of the toner sensor 19 and be detected. FIG. 5 shows a case where the toner bottle 6 is sufficiently filled with toner. This model of toner discharge from the toner bottle indicates that a relatively large amount of toner passes immediately before the toner sensor 19.

  In FIG. 6, the magnetic bridge sensor (secondary winding) induces the toner supply when the toner amount in the toner bottle 6 is full for a predetermined time (here, 1 second) and the toner is supplied at a large toner supply flow rate. The graph which plotted the output voltage value for every 1 msec is shown.

  When the transition of the voltage value induced in the magnetic bridge sensor is a function f (x) [x is time], the amount of toner replenished (and hence the replenishment flow rate) actually discharged from the toner bottle and the function f (x) The integral value has a very strong correlation. This integral value is a value obtained by definite integration of the function f (x) from time 0 msec to 1000 msec.

Here, as shown in FIG. 7, the integral value is approximated by the area S of the sum of the areas of the voltage values obtained by dividing the graph of FIG. 6 into blocks every 50 msec. That is,
∫f (x) dx≈area S
It becomes. By expressing a block (rectangle) divided every 50 msec at this time as a block of 0 msec as S0, a block of 50 msec as S50,.
Area S = S0 + S50 + S100 + ... + S900 + S950 + S1000
It becomes. Therefore,
Area S = 0 + (4x50) + (5x50) + ... + (5x50) + (6x50) + (3x50)
= 4750

This
∫f (x) dx ≒ 4750 Formula (1)
And can be approximated.

  FIG. 8 shows a model of toner discharge from the toner bottle when the toner having the same cohesion degree as in the example shown in FIG. 6 is used and the amount of toner in the toner bottle is small. From this figure, it can be seen that the amount of toner passing just before the toner sensor 19 is smaller than in the case of FIG.

  FIG. 9 shows a graph in which the output voltage value induced in the magnetic bridge sensor is plotted every 1 msec when toner is supplied for 1 second when the toner supply flow rate is relatively low (Low).

  Similarly to the above, assuming that the transition of the output voltage value induced in the magnetic bridge sensor is a function g (x) [x is time], the toner replenishment amount actually discharged from the toner bottle, the replenishment flow rate, and the function g The integral value of (x) has a very strong correlation. This integral value is a value obtained by definite integration of the function g (x) from time 0 msec to 1000 msec.

As shown in FIG. 10, the total area T of the areas obtained by dividing the graph of FIG. 9 into blocks every 50 msec is approximated as an integral value.
Area T = 1600

Therefore,
∫g (x) dx ≒ 1600 Formula (2)
And can be approximated.

  As shown in FIG. 11, the relationship between the integral value of the function in which the output voltage value induced in the magnetic bridge sensor is plotted every 50 msec when toner is supplied for 1 second, and the toner supply flow rate from the toner bottle at that time. It can be seen that there is a strong correlation as described above. That is, when a function in which the output voltage value induced in the magnetic bridge sensor is plotted every 50 msec in the toner replenishment for 1 second is integrated, data corresponding to the amount of toner replenished from the toner bottle at that time is obtained. Can be sought.

  Based on the toner detection signal of the toner sensor 19, the control unit C obtains the integral value as described above, and further obtains the toner replenishment amount (and hence the replenishment flow rate) discharged from the toner bottle based on the integral value. .

  In the present embodiment, the toner replenishment amount obtained in this way is used for two different controls.

  In the first control, the developer supply control means realized by the control unit C determines the supply amount (that is, the supply flow rate) of toner from the toner bottle within a unit time based on the obtained toner supply amount. The toner bottle rotation driving mechanism 10 in the toner replenishing device 8 is controlled to control the rotation speed of the toner bottle so that the amount is fixed.

  The second control is to control the amplitude (Vpp) of the AC voltage according to the rotational speed of the developer storage container by the AC voltage control means realized by the control unit C.

  For these first and second controls, only the first control may be employed, or both may be used in combination.

  FIG. 12A shows a configuration example of a control data table 30a that can be used in the first control. This control data table 30a includes a range of toner replenishment amount (ie, toner replenishment flow rate) per unit time (second), a range of integral values corresponding to the range, and the number of rotations per unit time (minute) of the toner bottle. That is, an example of the rotation speed is shown. The “toner replenishment flow rate” in FIG. 12 is shown for explanation, and it is sufficient for the actual control to have data of “integral value” and “rotational speed”. As can be seen from FIG. 12, the larger the “integrated value”, the larger the “toner replenishment flow rate” and the smaller the “rotational speed” per unit time.

  FIG. 12B shows a configuration example of a control data table 30b that can be used when performing the second control in addition to the first control. The control data table 30b is obtained by adding an item “development bias AC component (Vpp)” to the configuration of the control data table 30a.

  Usually, when the rotation speed of the toner bottle is increased, the toner in the toner bottle 6 is damaged from the guide portion inside the toner bottle 6 or the collision between the toners. Specifically, the external additive externally added to the developer surface for improving the developability is liberated or buried. As a result, the desired developability may not be obtained.

  On the other hand, a developing device that visualizes the electrostatic image by flying developer on the electrostatic latent image formed on the photosensitive drum 1 formed by the exposure unit includes an AC voltage (development bias AC component) and a DC voltage ( Development bias DC component) is superimposed. Therefore, when the rotation speed of the toner bottle is increased, the amplitude (Vpp) of the developing bias AC component is increased from the standard amplitude value (for example, increased from 1600 V to 2000 V). This compensates for the effects of toner damage by increasing the amplitude of the AC voltage even if the external additive externally added to the developer surface is released or buried due to an increase in the rotation speed of the toner bottle. As a result, it is possible to prevent deterioration in developability and to obtain a high-quality image.

  More specifically, the development bias AC component (Vpp) makes the Vpp value higher than a normal value when the rotation speed of the toner bottle is high. In this example, Vpp is set to a normal value of 1600 V in the A and B regions where the rotational speed is relatively low, and Vpp is set to 1800 V which is higher than the normal value in the C region where the rotational speed is high. Further, in the D region where the rotation speed is high, Vpp is set to 2000 V, which is even higher.

  Next, specific processing steps of main processing in the present embodiment will be described with reference to the flowchart of FIG. This process is realized by the CPU of the control unit C reading and executing a program from the memory.

  The toner bottle rotation driving mechanism 10 is controlled to rotate the toner bottle at a predetermined rotation speed (22 rpm in this case), thereby starting toner supply from the toner bottle to the hopper unit 7 (S11).

  Next, the output voltage (voltage value) induced in the toner sensor 19 as a magnetic bridge sensor is monitored at predetermined unit time intervals (in this case, every 50 msec) (S12). Further, the voltage transition is set as a function f (x) (S13), and this function f (x) is integrated (S14). This monitoring and integration continues until a predetermined time (here, 1 second) elapses (S15).

  When the predetermined time has elapsed, the control data table is referred to from the obtained integral value, and the following threshold determination is performed in order to determine the toner replenishment flow rate (S16). Thus, by determining the actual toner supply flow rate within the “predetermined time” as a relatively short time immediately after the start of toner supply, the subsequent toner supply speed can be set to an appropriate value.

  As a result of the threshold determination, the rotation speed of the toner bottle is controlled based on the obtained toner supply flow rate.

  In the example of the control data table 30a shown in FIG. 12A, when the integral value belongs to the A region (3000 or more) (S17, Yes), it is determined that the toner replenishment flow rate is extremely large (S18), and the toner bottle The rotational speed is greatly reduced (S19). That is, it is reduced from 22 rpm to 5 rpm.

  When the integrated value belongs to the B region (1500 or more and less than 3000) (S20, Yes), it is determined that the toner replenishing flow rate is large (S21), and the toner bottle speed is reduced (S22). That is, the pressure is reduced from 22 rpm to 15 rpm.

  When the integrated value belongs to the C region (500 or more and less than 1500) (S23, Yes), it is determined that the toner replenishing flow rate is small (S24), and the toner bottle speed is increased (S25). That is, the pressure is increased from 22 rpm to 30 rpm.

  If the integrated value belongs to the D region (0 or more and less than 500) (S26, Yes), it is determined that the toner replenishing flow rate is extremely small (S27), and the toner bottle speed is greatly increased (S28). That is, the pressure is increased from 22 rpm to 60 rpm.

  Thereafter, when the amount of toner in the hopper section 7 exceeds the reference amount due to the supply of toner from the toner replenishing device 8, a replenishment stop signal is issued by the toner sensor. The drive of the drive source in the rotation drive mechanism 10 is stopped by this supply stop signal, and the rotation of the toner bottle 6 is stopped (S29).

  In this way, when toner is replenished from the toner replenishing device 8 to the developing device 3 via the hopper unit 7, if the toner replenishment amount detected based on the output of the toner sensor 19 (magnetic bridge sensor) decreases, the rotation occurs. The rotation number (rotation speed) per unit time of the toner bottle 6 by the rotation drive mechanism 10 is set to be large by the control means. As a result, for example, when the amount of toner discharged in one rotation decreases as the amount of remaining toner in the toner bottle 6 decreases, or when the amount of toner is large but left for a long time between high temperature and high humidity. Accordingly, even when the toner aggregation degree increases and the fluidity of the toner decreases, the actual replenishment amount can be determined, so that the toner supply speed to the hopper 7 is prevented from decreasing.

  Accordingly, the supply of toner from the toner replenishing device 8 to the hopper unit 7 is sufficient for the supply of toner from the hopper unit 7 to the developing unit 3, so that the amount of toner consumed in the developing unit 3 is increased. The developer 3 is replenished with a stable amount of toner with respect to the amount, so that a good visible image can always be obtained.

  Further, by controlling the rotation speed of the toner bottle stepwise in accordance with the toner replenishment flow rate from the toner bottle 6, the toner bottle opening due to excessive supply, generally seen when the toner weight in the toner bottle is large, is observed. It is possible to simultaneously prevent the toner from being ejected (flushing).

  FIG. 14 shows a specific processing flow of main processing in the present embodiment in the case where the second control is performed in addition to the first control. In FIG. 14, the same processing steps as the processing steps shown in FIG. 13 are denoted by the same reference numerals, and redundant description is omitted.

  Processing steps corresponding to the second control are steps S19a, 22a, 25a, and 28a following processing steps S19, 22, 25, and 28, respectively. In steps S19a and 22a, Vpp is set to 1600V, in step 25a Vpp is set to a higher 1800V, and in step 28a, Vpp is set to a higher 2000V.

  Next, FIG. 15 shows a modified example of the configuration of the hopper section 7. The toner replenishing path from the opening to the hopper 7 has a cylindrical shape. The cross-sectional shape of the cylinder is not particularly limited, but in this example, it is a quadrangular shape. By making the toner replenishment path 23 cylindrical, the toner can easily pass through the front surface of the toner sensor 19 (magnetic bridge sensor) that detects toner, and detection omission can be prevented.

  FIG. 16 shows another modification of the configuration of the hopper portion 7. In this modification, the toner supply path has an inclined surface 24 on which the toner discharged from the opening of the toner bottle slides down. The toner sensor 19 is installed on the outer wall of the inclined surface. As a result, the replenished toner comes closer to the toner sensor 19 and a further effect of preventing detection omission can be expected.

  As described above, according to the present embodiment, in the image forming apparatus having the toner replenishing device provided with the toner bottle and the hopper unit that temporarily receives the toner discharged from the toner bottle, the supplied toner amount is inexpensively configured. By accurately detecting the amount of toner supplied from the toner bottle and controlling the amount of toner supplied from the toner bottle appropriately, the developer is not affected by the influence of the usage environment, the toner remaining amount and the leaving time of the toner bottle, the aggregation degree of the toner in the toner bottle, etc. The toner can be replenished stably. As a result, it is possible to always form a good visible image and to prevent flushing in the image forming apparatus.

  The preferred embodiments of the present invention have been described above, but various modifications and changes other than those mentioned above can be made. For example, although a magnetic bridge sensor is used as the toner sensor, the present invention is not limited to this. The number of areas for determining the threshold value of the integral value, the number of variable speed stages, the threshold value, the control value, etc. are merely examples, and the present invention is not limited to these specific numerical values. For example, the control data table in FIG. 12 shows only an example in which the rotation speed of the toner bottle is increased or decreased. However, an integral value range that maintains the initial rotation speed (22 rpm in the above example) may be provided. Further, the target value may be obtained by using a predetermined calculation formula without using the data table or by conditional branching in the program processing. In the control flow of FIGS. 13 and 14, a step for maintaining the initial rotational speed is provided, and when the integral value is obtained, a process for maintaining the initial rotational speed can be executed. Although the hopper portion is shown as a separate structure from the developing device, the present invention can also be applied to a device in which the developing device is integrated with the developing device continuously with the hopper portion of the present embodiment.

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum 2 ... Charging part 3 ... Developing device 4 ... Transfer part 5 ... Fixing device 6 ... Toner bottle 6A ... Projection 6B ... Tip part 6C ... Discharge opening 6D ... Slide lid 7 ... Hopper part 8 ... Toner supply device 9 ... Toner bottle mounting part 10 ... Toner bottle rotation drive mechanism 11 ... Agitator in hopper 12 ... Toner supply port 13 ... Toner conveying screw 14 ... Toner sensor (developer remaining amount detecting means)
DESCRIPTION OF SYMBOLS 15 ... Rotation drive mechanism 16 ... Toner sensor 17 ... Developer supply port 19 ... Toner sensor (developer detection means)
DESCRIPTION OF SYMBOLS 20 ... Magnetic bridge sensor 20a ... Sensor main-body part 20b ... Detection head 20c ... Signal line 24 ... Inclined surface 30a ... Control data table 30b ... Control data table A ... Recovery mechanism (cleaning part)
B ... Image exposure unit C ... Control unit D ... High pressure generator

Claims (11)

In an image forming apparatus including a developing unit that visualizes an electrostatic latent image formed on an image carrier with a developer,
A hopper unit that contains the developer and temporarily stores the developer supplied from a developer storage container that is detachable from the image forming apparatus main body, and supplies the developer to the developer;
A developer detecting means provided in a developer replenishment path of the hopper section through which the developer supplied into the hopper section passes and detects the supplied developer;
Developer storage container driving means for causing the developer storage container to perform a supply operation and supplying the developer from the developer storage container into the hopper portion;
When replenishing from the developer storage container to the hopper, the developer by the developer storage container driving means is based on the output value of the developer detecting means within a predetermined time during replenishment. An image forming apparatus comprising: a developer supply control unit that changes a supply operation of the storage container.   The developer supply control means is based on an integration value obtained by integrating the transition of the output value of the developer detection means within the predetermined time within the predetermined time during the replenishment, The image forming apparatus according to claim 1, wherein a replenishment amount of the developer is determined.   The developer supply control means detects the developer by the developer detection means in a unit time period within the predetermined time and adds the replenishment amount based on an addition value obtained by adding the detection output value within the predetermined time. The image forming apparatus according to claim 2, wherein:   The developer supply control means controls the developer storage container driving means according to the determined supply amount so that the developer supply amount from the developer storage container within a unit time becomes a predetermined amount. The image forming apparatus according to claim 1, 2, or 3.   The developer storage container has a spiral protrusion on an inner wall peripheral surface thereof, and the developer storage container driving means rotates the developer storage container to rotate the developer storage container to use the developer as a developer guide. The image forming apparatus according to claim 4, wherein the developer supply control unit controls the rotation speed of the developer storage container. AC voltage application means for applying an AC voltage (development bias AC component) to the developing device in order to cause the developer to fly to the image carrier
The image forming apparatus according to claim 5, further comprising an AC voltage control unit that controls an amplitude (Vpp) of the AC voltage according to a rotation speed of the developer storage container.   The developer detection means has a sensor for detecting the amount of developer present in the detection area, and the sensor is provided almost directly below the opening of the developer storage container for discharging the developer. An image forming apparatus according to claim 1, wherein:   The hopper has a developer replenishment path through which the developer discharged from the opening of the developer storage container passes, and the sensor is disposed facing the developer replenishment path. The image forming apparatus according to claim 7.   The image forming apparatus according to claim 8, wherein the developer supply path has a wall surface or a cylindrical shape formed in the hopper portion.   The image forming apparatus according to claim 8, wherein the developer supply path has an inclined surface on which the developer discharged from the opening of the developer storage container slides.   The image forming apparatus according to claim 1, wherein the hopper portion is formed integrally with the developing device.

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