JP2013205480A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To identify the presence of toner in a housing part with high accuracy even if the amount of toner adhered on a wall surface of the housing part housing the toner changes according to the environment.SOLUTION: An image forming device includes: a developing unit 4; a buffer part 30 for storing toner to be supplied to the developing unit 4; a capacitive sensor 32a provided on a wall surface of the buffer part 30 to detect a dielectric constant between an electrode 40a and an electrode 41a; a capacitive sensor 32b provided on a wall surface of the buffer part 30 to detect a dielectric constant between an electrode 40b and an electrode 41b having a larger distance than between the electrode 40a and the electrode 41a; and a CPU 120 that identifies whether the amount of toner in the buffer part 30 is equal to or larger than a target amount, on the basis of an output voltage Va of the capacitive sensor 32a and an output voltage Vb of the capacitive sensor 32b.

Description

  The present invention relates to processing for replenishing developer toner through a storage container that temporarily stores toner in an electrophotographic image forming apparatus.

  An electrophotographic image forming apparatus visualizes an electrostatic latent image on an image carrier as a toner image using toner in a developing device. When the amount of toner in the developing device has decreased below a predetermined amount, the toner is supplied from a container (hereinafter referred to as a toner bottle) containing toner to the developing device through a buffer unit that temporarily accumulates toner. Furthermore, since the image forming apparatus having such a configuration is provided with the buffer unit, the toner accumulated in the buffer unit can be replenished to the developing unit even after the toner in the toner bottle becomes empty. The image forming operation can be performed while the toner bottle is replaced.

  As a sensor for detecting the amount of toner in the buffer unit, an electric field is formed between electrodes arranged in parallel at regular intervals, and based on the capacitance that changes according to the dielectric constant of the substance in the formed electric field, An electrostatic capacitance type that detects the remaining amount of toner is known. This is because the dielectric constant of air is higher than the dielectric constant of toner, so that the capacitance between the electrodes decreases when the toner near the electrodes decreases.

  By the way, when the amount of water vapor in the atmosphere increases, the dielectric constant of the atmosphere increases. Therefore, although the same amount of toner is accumulated when the humidity changes, the capacitance detected by the sensor changes, and the amount of toner cannot be detected accurately.

  Therefore, the image forming apparatus disclosed in Patent Document 1 has the first sensor at a position where it can come into contact with the accumulated toner, and has the second sensor at a position where it does not come into contact with the toner. Is corrected using the capacitance detected by the second sensor.

  With this configuration, the second sensor detects the capacitance according to the dielectric constant of the atmosphere, and the detection result is used to correct the capacitance detected by the first sensor. The remaining amount of toner can be detected without being affected by the amount of water vapor in the atmosphere.

JP 2001-92231 A

  Here, when the humidity in the buffer portion increases, the amount of toner adhering to the wall surface of the buffer portion increases. Therefore, when the humidity in the buffer portion increases, the amount of toner adhering to the vicinity of the sensor increases and the proportion of air in the vicinity of the sensor decreases, so the dielectric constant between the electrodes of this sensor decreases and is detected by the sensor. Capacitance will decrease. As a result, when the capacitance detected by the sensor becomes equal to or less than the value at which the toner should be supplied to the buffer unit, the toner is not supplied even though the toner in the buffer unit is insufficient. is there.

  Further, when the humidity in the buffer unit decreases, the amount of toner adhering to the vicinity of the sensor decreases. As a result, even though the target amount of toner in the buffer unit is accumulated, the capacitance detected by the sensor is higher than a threshold value for determining that the toner should be supplied to the buffer unit. In addition, there is a possibility that the toner is excessively supplied to the buffer unit.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus that can suppress erroneous detection of the amount of toner due to environmental fluctuations.

  In order to solve the above-described problem, an image forming apparatus according to claim 1 includes a developing unit that develops an electrostatic latent image formed on a photoreceptor with toner, and an accumulation that accumulates toner for replenishing the developing unit. A first signal corresponding to the amount of toner provided between the first detection surface and the first distance in a direction orthogonal to the first detection surface provided on the container and the wall surface of the storage container; First output means for outputting, and provided on the wall surface of the storage container, in a direction perpendicular to the second detection surface, from the second detection surface to a second distance longer than the first distance. There is data indicating the correspondence between the second output means for outputting the second signal corresponding to the amount of toner in between, the first signal, and the correction value for correcting the second signal. Correction determined based on stored storage means, the first signal and the data If the difference between the second signal and the second signal is not less than a specified value, the amount of toner accumulated in the storage container is identified as not less than a target amount, and if the difference is less than the specified value, And identifying means for identifying that the amount of toner accumulated in the accumulation container is less than the target amount.

  An image forming apparatus according to another claim includes a developing unit that develops an electrostatic latent image formed on a photoreceptor with toner, a storage container that accumulates toner for replenishing the developing unit, A first signal is provided on the wall surface of the storage container and outputs a first signal corresponding to the amount of toner between the first detection surface and the first distance in a direction orthogonal to the first detection surface. 1 between the first detection means and a second distance longer than the first distance in a direction orthogonal to the second detection surface provided on the wall surface of the storage container. There is data indicating a correspondence relationship between the second output means for outputting a second signal corresponding to the amount of toner, the first signal, and a threshold value for determining that the storage container should be replenished with toner. The stored storage means and the second signal are converted into the first signal and the data. The amount of toner accumulated in the accumulation container is identified as being equal to or greater than the target amount, and accumulation in the accumulation container is performed if the second signal is less than the threshold. And identifying means for identifying that the amount of toner applied is less than the target amount.

  According to the present invention, it is possible to suppress erroneous detection of the presence or absence of toner due to environmental fluctuations.

Schematic diagram of main parts of image forming apparatus Cross section of the main part of the toner supply mechanism Schematic diagram of the main part of the capacitance sensor 32a and an image diagram of the electric field formed around the sensor Schematic diagram of the main part of the capacitance 32b sensor and an image diagram of the electric field formed around the sensor Bargram comparing output voltage of capacitance sensor 32a and capacitance sensor 32b Data indicating the correspondence between the output voltage Va and the correction value Vc Control block diagram of image forming apparatus The flowchart figure which shows the replenishment process which replenishes toner to a developing device. Data indicating the correspondence between the output voltage Va and the specified value Vt

(First embodiment)
FIG. 1 is a schematic cross-sectional view of an image forming apparatus 100 of the present embodiment.

  The image forming apparatus 100 includes a photosensitive drum 1 that carries a toner image of a black color component, a charger 2 that charges the photosensitive drum 1, and a photosensitive drum 1 that forms an electrostatic latent image on the photosensitive drum 1. It has the exposure apparatus 3 which exposes. Further, the image forming apparatus 100 includes a developing unit 4 that visualizes an electrostatic latent image formed on the photosensitive drum 1 as a toner image using a developer having toner, and a recording material P such as paper. A transfer roller 5 for transferring is provided. The image forming apparatus 100 also includes a drum cleaner 6 that removes toner remaining on the photosensitive drum 1 after the toner image is transferred.

  The recording material P onto which the toner image has been transferred by the transfer roller 5 is conveyed to the fixing device 7. The fixing device 7 includes a heating roller 71 and a pressure roller 72, and fixes the toner image carried on the recording material P by heat and pressure.

  Next, an image forming operation of the image forming apparatus 100 will be described.

  When the image forming apparatus 100 receives image data transmitted from an external device such as a PC (not shown) via the I / F 110 (FIG. 7), the image forming apparatus 100 rotates the photosensitive drum 1 in the direction of the arrow, and the charger 2 The surface of the photosensitive drum 1 is uniformly charged. The image data transmitted from the PC is subjected to various image processing by the CPU 120 (FIG. 7) and transferred to the exposure apparatus 3. The exposure apparatus exposes a laser beam modulated according to image data transferred from the CPU 120 onto the photosensitive drum 1 as a photosensitive member. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 1.

  When the electrostatic latent image on the photosensitive drum 1 is visualized by the toner of the developing device 4, it is carried on the photosensitive drum 1 as a toner image. This toner image is conveyed to the transfer portion N where the transfer roller 5 presses the photosensitive drum 1 as the photosensitive drum 1 rotates in the arrow direction. At this time, the recording material P in the paper feed cassette 8 is fed one by one by the pickup roller 81 and conveyed toward the transfer unit N. The recording material P transported by the paper feed roller pair 82 and the transport roller pair 83 is transferred so that the registration roller 84 adjusts the paper position and feed timing, and comes into contact with the toner image on the photosensitive drum 1. Part N is supplied.

  When the toner image on the photosensitive drum 1 and the recording material P sent out from the registration roller 84 enter the transfer portion N, a transfer voltage is applied to the transfer roller 5, and the toner image on the photosensitive drum 1 is transferred onto the recording material P. Is transcribed.

  The recording material P onto which the toner image has been transferred at the transfer unit N is conveyed to the fixing device 7. In the fixing device 7, the heating roller 71 and the pressure roller 72 sandwich and convey the toner image and the recording material P and are heated by a heater (not shown) provided in the heating roller 71, so that the toner image is recorded. Fix to P. Thereafter, the recording material P on which the toner image is fixed is discharged from the image forming apparatus by the discharge roller pair 85.

  Next, the toner replenishing mechanism of the developing device 4 provided in the image forming apparatus of this embodiment will be described with reference to FIG. The toner replenishing mechanism according to the present exemplary embodiment is configured so that toner is supplied from the toner bottle 31 that is replaceably mounted to the main body of the image forming apparatus 100 to the developing device 4 via a buffer unit 30 serving as a storage container that temporarily stores toner. It is the composition which replenishes.

  The developing device 4 contains toner that is a one-component developer, and this toner is carried on the developing sleeve 4C by a magnetic force from a magnet (not shown) and develops the electrostatic latent image as a toner image. As a result, the toner in the developing device 4 is consumed. The developing device 4 is provided with an inductance sensor 34 for detecting the amount of toner in the developing device 4 based on the magnetic permeability of the developer.

  The buffer unit 30 is provided with a conveying screw 33 for supplying toner in the buffer unit 30 to the developing device 4 and a capacitance sensor unit 32 for detecting the remaining amount of toner in the buffer unit 30. ing. In the present embodiment, when the amount of toner in the developing device 4 detected by the inductance sensor 34 is equal to or less than a predetermined amount, the conveying screw 33 is rotationally driven by the screw motor 126 (FIG. 7) to develop from the buffer unit 30. Toner 4 is replenished with toner. Note that the amount of toner replenished to the developing device 4 by the rotation of the conveying screw 33 is roughly determined. When the amount of toner in the buffer unit 30 detected by the capacitance sensor unit 32 becomes equal to or less than the target amount, the toner bottle 31 is driven to rotate in the direction of the arrow, and toner is supplied from the toner bottle 31 to the buffer unit 30. The

  The above-described toner bottle 31 contains toner to be replenished to the buffer unit 30, and a helical guide groove for conveying the toner is formed on the inner surface of the toner bottle 31. The toner bottle 31 is rotationally driven by the bottle motor 125 (FIG. 7), so that the toner in the toner bottle 31 is replenished from the opening to the buffer unit 30. It should be noted that the amount of toner replenished from the toner bottle 31 to the buffer unit 30 within a certain time varies depending on the remaining amount of toner in the toner bottle 31.

  FIG. 2B is an enlarged view of the capacitance sensor unit 32 provided on the wall surface of the buffer unit 30. In the present embodiment, the position at which the electrostatic capacity sensor unit 32 is attached is a buffer that covers the electrostatic capacity sensor unit 32 with the toner when 500 [mg] or more of toner is accumulated in the buffer section 30. The wall surface of the portion 30 was used.

  The electrostatic capacity sensor unit 32 according to the present embodiment has a longer distance than the electrostatic capacity sensor 32a that can detect the dielectric constant of the electrostatic capacity sensor 32a for detecting the amount of toner in the buffer unit 30. And a capacitance sensor 32b. The distance that can detect the dielectric constant of the toner is a distance in a direction orthogonal to the detection surfaces of the capacitance sensors 32a and 32b.

  FIG. 3 is a schematic view and a perspective view of the detection surface of the capacitance sensor 32a, and FIG. 4 is a schematic view and a perspective view of the detection surface of the capacitance sensor 32b. The arrows in FIGS. 3B and 4B indicate the electric field strength, and the thicker the arrow, the stronger the electric field strength.

  As shown in FIG. 3A, the capacitance sensor 32a includes a plurality of electrodes 40a configured in a comb-teeth shape having a width Da and a plurality of electrodes 41a similarly configured in a comb-teeth shape having a width Da. It is formed on the substrate 42a so as to have an interelectrode distance Ga. In this embodiment, the inter-electrode distance Ga between the electrode 40a and the electrode 41a is set to be less than half of the width Da of the electrodes 40a and 41a according to the experiments of the present inventors. Specifically, the length La of the electrodes 40a and 41a was 30 [mm], the width Da was 0.3 [mm], and the inter-electrode distance Ga was 0.01 [mm]. The width Da is the length in the direction orthogonal to the longitudinal direction of the convex portions of the electrodes 40a and 41a. Here, the electrode 40a corresponds to a first electrode, and the electrode 41a corresponds to a second electrode.

  In the present embodiment, the electrode 40a and the electrode 41a do not overlap each other, and each of the plurality of electrodes constituting the electrode 40a and each of the plurality of electrodes constituting the electrode 41a are alternately positioned. The configuration is printed on the substrate 42a. Note that the electrodes 40a and 41a are not limited to this configuration, and may be at least a pair of electrodes arranged to face each other as long as they are separated so that an electric field is formed between these electrodes.

  In addition, since the electric field strength in the vicinity of the electrostatic capacity sensor 32a is larger than the electric field strength in the far position of the electrostatic capacity sensor 32a, the electrostatic capacity sensor 32a has a dielectric constant when the toner adheres to the wall surface of the buffer unit 30. As the rate increases, the output voltage Va is increased. That is, the capacitance sensor 32a corresponds to a first output unit that outputs a voltage Va as a first signal corresponding to the dielectric constant of the toner. Note that the length La, the width Da, and the inter-electrode distance Ga of the capacitance sensor 32a are not limited to the dimensions of the present embodiment.

  On the other hand, as shown in FIG. 4A, the capacitance sensor 32b includes a plurality of electrodes 40b configured in a comb-teeth shape having a width Db and a plurality of electrodes 41b configured similarly in a comb-teeth shape having a width Db. Are formed on the substrate 42b so as to be the interelectrode distance Gb. In the present embodiment, the inter-electrode distance Gb between the electrode 40b and the electrode 41b is set to be half or more of the width Db of the electrodes 40b and 41b according to the experiment of the present inventor. Specifically, the length Lb of the electrodes 40b and 41b was 30 [mm], the width Db was 0.5 [mm], and the interelectrode distance Gb was 0.5 [mm]. The width Db is the length in the direction orthogonal to the longitudinal direction of the convex portions of the electrodes 40b and 41b. Here, the electrode 40b corresponds to a third electrode, and the electrode 41b corresponds to a fourth electrode.

  In the present embodiment, the electrode 40b and the electrode 41b do not overlap each other, and each of the plurality of electrodes constituting the electrode 40b and each of the plurality of electrodes constituting the electrode 41b are alternately positioned. The configuration is printed on the substrate 42b. Note that the electrodes 40b and 41b are not limited to this configuration, and may be at least a pair of electrodes arranged to face each other as long as they are separated so that an electric field is formed between these electrodes. The capacitance sensor 32b corresponds to a second output unit that outputs a voltage Vb as a second signal corresponding to the dielectric constant of the toner. Note that the length Lb, the width Db, and the inter-electrode distance Ga of the capacitance sensor 32b are not limited to the dimensions of the present embodiment.

  In addition, the difference between the electric field strength near the electrostatic capacitance sensor 32b and the electric field strength far from the electrostatic capacitance sensor 32b is larger than the difference between the electric field strength near the electrostatic capacitance sensor 32a and the electric field strength far from the electrostatic capacitance sensor 32a. small. Thus, the distance that the electrostatic capacity sensor 32b can detect the dielectric constant of the toner in the direction orthogonal to the detection surface is larger than the distance that the electrostatic capacity sensor 32a can detect the dielectric constant of the toner in the direction orthogonal to the detection surface. Also gets longer. In the present embodiment, the substrate 42a of the capacitance sensor 32a corresponds to the first detection surface, and the substrate 42b of the capacitance sensor 32b corresponds to the second detection surface. Further, the first distance at which the dielectric constant of the toner can be detected by the capacitance sensor 32a corresponds to the region from the substrate 42a to the first distance, and the dielectric constant of the toner can be detected by the capacitance sensor 32b. The second distance corresponds to a region from the substrate 42b to the second distance.

  Here, according to the study of the present inventor, the inter-electrode distance Ga, which is the distance between the electrode 40a and the electrode 41a of the capacitance sensor 32a, is the distance between the electrode 40b and the electrode 41b of the capacitance sensor 32b. It was found that it should be shorter than the interelectrode distance Gb. By doing so, the distance at which the electrostatic capacity sensor 32b can detect toner in the direction orthogonal to the detection surface is longer than the distance at which the electrostatic capacity sensor 32a can detect toner in the direction orthogonal to the detection surface. can do.

  Next, changes in the output values of the capacitance sensors 32a and 32b that change depending on the state of the toner in the buffer unit 30 will be described with reference to FIG. In FIG. 5, the left three are the output values of the capacitance sensor 32a, and the right three are the output values of the capacitance sensor 32b. 5A shows an output value in a state where toner is not attached to the wall surface in the buffer unit 30, and FIG. 5B shows an output value in a state where toner is less than the target amount but the toner is attached to the wall surface. C) Each of the output values in a state where the toner is equal to or larger than the target amount is shown.

  When the detection result of FIG. 5 is examined, the output voltage of the capacitance sensor 32a is larger than the output voltage of the capacitance sensor 32b in any of (A) to (C). Further, the output voltage of the capacitance sensor 32a has almost no difference between (B) and (C). On the other hand, although the output voltage of the capacitance sensor 32b has a small dynamic range, there is a difference between (B) and (C).

  Here, the dielectric constant of the toner in the buffer unit 30 varies depending on the humidity of the environment in which the apparatus is placed, but the amount of toner attached to the wall surface of the buffer unit 30, that is, the detection surface of the capacitance sensor unit 32. The amount of toner to be changed also varies depending on the humidity. For this reason, even if an attempt is made to detect the amount of toner in the buffer unit 30 based on the output value of the capacitance sensor 32b, the dynamic range of the capacitance sensor 32b is small, so that the toner in the buffer unit 30 exceeds the target amount. It becomes difficult to detect whether or not it is.

  Therefore, in the present embodiment, based on the output value of the capacitance sensor 32a, the amount of change in the output voltage of the capacitance sensor 32b is predicted due to the influence of toner adhering to the detection surface of the capacitance sensor 32b. The output value of the capacitance sensor 32b is corrected based on the change. Specifically, the toner in the buffer unit 30 exceeds the target amount according to the result of correcting the output voltage of the capacitance sensor 32b with a correction value determined based on the output voltage of the capacitance sensor 32a. Whether or not there is is identified with high accuracy.

FIG. 6 is data showing the correspondence between the output voltage Va of the capacitance sensor 32a and the correction value Vc studied by the present inventors. In this embodiment, the correction value Vc corresponding to the output voltage Va is determined by referring to this data, and the toner in the buffer unit 30 is based on the voltage difference Vbc that is the difference between the output voltage Vb and the correction value Vc. Is configured to identify whether or not is less than the target amount. Specifically, if the voltage difference Vbc is equal to or greater than the threshold value Vt, the toner is accumulated in the buffer unit 30 over the target amount, and if the voltage difference Vbc is less than the threshold value Vt, the toner in the buffer unit 30 is targeted. It is determined that the amount is less than the required amount. In the present embodiment, the threshold value Vt is a predetermined value that is determined in advance. In the following, the voltage difference Vbc is calculated using the expression 1 from the output voltage Vb from the capacitance sensor 32b and the correction value Vc.
Vbc = Vb−Vc (Formula 1)

  Hereinafter, a replenishment process in which the image forming apparatus of the present embodiment replenishes toner to the developing device 4 will be described with reference to FIGS. 7 and 8.

  FIG. 7 is a control block diagram of the image forming apparatus. The CPU 120 is a control circuit that controls the entire image forming apparatus. The ROM 128 stores a control program for controlling various processes executed by the image forming apparatus. The RAM 127 is a system work memory for the CPU 120 to operate. Note that a program for executing the flowchart of FIG. 8 is stored in the ROM 128 and executed by being read by the CPU 120.

  When a signal instructing the replenishment of toner to the buffer unit 30 is input from the CPU 120, the driving circuit 123 rotates the toner bottle 31 by the bottle motor 125 and replenishes the buffer unit 30 with toner in the toner bottle 31. . When a signal instructing replenishment of toner from the CPU 120 to the developing device 4 is input, the driving circuit 124 rotates the transport screw 33 by the screw motor 126 to replenish the toner in the buffer unit 30 to the developing device 4. .

  The inductance sensor 34 is a sensor that detects the amount of toner in the developing device 4 as a voltage Vi corresponding to the magnetic permeability. When the amount of toner in the developing device 4 increases, the output voltage Vi also increases. When the amount of toner in 4 decreases, the output voltage Vi also decreases. Since the inductance sensor 34 has a known configuration, detailed description thereof is omitted.

  The electrostatic capacity sensor 32a receives a signal instructing replenishment of toner from the CPU 120 to the developing device 4 to the drive circuit 124, and then an AC voltage is applied to the input sensor 40a and the output electrode 41a. Outputs voltage according to the capacitance between. Similarly, the electrostatic capacity sensor 32b is configured such that an input voltage is applied to the input side electrode 40b and the output side electrode after a signal instructing the toner supply from the CPU 120 to the developing device 4 is input to the drive circuit 124 and then an AC voltage is applied. The voltage according to the electrostatic capacitance between 41b is output.

  The operation unit 22 includes a touch panel, a start key for starting an image forming operation, a numeric keypad for inputting the number of copies, a cancel key for returning input contents to default values, and the like. The touch panel is configured to notify the user of the state of the image forming apparatus 100 by a signal from the CPU 120. The configuration for notifying the user of the state of the image forming apparatus may be a display of a PC connected to be communicable with the image forming apparatus through a network.

  Next, processing for supplying toner to the developing device 4 and the buffer unit 30 will be described with reference to FIG. This flowchart is executed when the CPU 120 reads a program stored in the ROM 128.

  First, the CPU 120 determines whether the amount of toner in the developing device 4 is less than a predetermined amount (S100). In step S100, when the voltage Vi output from the inductance sensor 34 is lower than the reference value Vr, the CPU 120 determines that the amount of toner in the developing device 4 is less than a predetermined amount.

  When the amount of toner in the developing device 4 is smaller than the predetermined amount in step S100, that is, when the output voltage Vi of the inductance sensor 34 is lower than the reference value Vr, the CPU 120 supplies toner from the buffer unit 30 to the developing device 4. Replenish (S101). In step S <b> 101, the CPU 120 inputs a signal instructing toner supply to the developing device 4 to the drive circuit 124, and rotates the conveying screw 33 by the screw motor 126. At this time, the CPU 120 determines the amount of toner in the developing device 4 based on the output voltage Vi of the inductance sensor 34, and exceeds the number of rotations necessary for the amount of toner in the developing device 4 to exceed a predetermined amount. The screw motor 126 is driven to rotate the conveying screw 33.

  Next, the CPU 120 determines the voltage between the output voltage Vb and the correction value Vc in order to identify whether or not the amount of toner in the buffer unit 30 detected using the capacitance sensors 32a and 32b is less than the target amount. It is identified whether or not the difference Vbc is less than the threshold value Vt (S102). In step S102, the CPU 120 applies an AC voltage to the capacitance sensors 32a and 32b, and detects the voltage Va output from the capacitance sensor 32a and the voltage Vb output from the capacitance sensor 32b. The CPU 120 determines the correction value Vc by referring to data (FIG. 6) indicating the correspondence relationship between the output voltage Va and the correction value Vc stored in advance in the ROM 128, and from the voltage Vb and the correction value Vc, the following equation 1 is obtained. It is identified whether or not the calculated voltage difference Vbc is less than the threshold value Vt. In step S102, the ROM 128 functions as a storage unit that stores data (FIG. 6) indicating the correspondence between the output voltage Va and the correction value Vc.

  In step S102, when the voltage difference Vbc between the correction value Vc and the output voltage Vb is equal to or larger than the threshold value Vt, the CPU 120 identifies that the amount of toner in the buffer unit 30 is equal to or larger than the target amount, and proceeds to step S100. . The CPU 120 repeats the steps S100 to S102, so that the toner in the developing unit 4 becomes less than the predetermined amount until the toner in the buffer unit 30 becomes less than the target amount. Continue to replenish toner.

  On the other hand, if the voltage difference Vbc between the correction value Vc and the output voltage Vb is less than the threshold value Vt in step S102, the CPU 120 identifies that the amount of toner in the buffer unit 30 is less than the target amount, and the toner bottle 31 Then, toner supply to the buffer unit 30 is started (S103). In step S <b> 103, the CPU 120 inputs a signal instructing supply of toner to the buffer unit 30 to the drive circuit 123, and starts rotating the toner bottle 31 by the bottle motor 125.

  Next, as in step S120, the CPU 120 identifies whether the amount of toner in the buffer unit 30 detected using the capacitance sensors 32a and 32b is less than the target amount (S104). Since the detailed process of step S104 is the same as that of step S102, detailed description here is omitted. If the difference between the correction value Vc and the output voltage Vb is greater than or equal to the threshold value Vt in step S104, the CPU 120 identifies that the amount of toner in the buffer unit 30 is greater than or equal to the target amount, and proceeds to step S100. To do.

  On the other hand, if the voltage difference Vbc between the correction value Vc and the output voltage Vb is less than the threshold value Vt in step S104, the CPU 120 identifies that the amount of toner in the buffer unit 30 is less than the target amount, and the buffer unit 30 Whether or not a predetermined time has elapsed since the start of toner replenishment is identified (S105). In step S <b> 105, the CPU 120 may be configured to count the time that has elapsed since the start of the replenishment of toner to the buffer unit 30 using a counter (not shown). If the elapsed time is less than the predetermined time in step S105, the CPU 120 proceeds to step S103 and continues to supply toner to the buffer unit 30.

  On the other hand, if the elapsed time is equal to or longer than the predetermined time in step S105, the CPU 120 stops the rotation of the bottle motor 125 via the drive circuit 123 and replaces the toner bottle 31 with the touch panel of the operation unit 22. Is displayed (S106). In step S106, the CPU 120 stops image formation until the toner bottle 31 is replaced by the user, and prohibits execution of image formation.

  In this way, the output value of the capacitance sensor 32b having a detection range wider than that of the capacitance sensor 32a is corrected based on the result of detecting the capacitance of the toner adhering to the detection surface by the capacitance sensor 32a. As a result, the presence or absence of toner in the buffer unit 30 can be identified with high accuracy.

(Second Embodiment)
This embodiment differs from the first embodiment described above in the following points. The other elements of the present embodiment are the same as those corresponding to the first embodiment described above, and a description thereof will be omitted.

  In the first embodiment, the output voltage Vb of the capacitance sensor 32b is corrected using the correction value Vc determined based on the output voltage Va of the capacitance sensor 32a, and the buffer is based on the corrected result. It is configured to identify whether or not the amount of toner in the unit 30 is greater than or equal to the target amount. On the other hand, in the present embodiment, the threshold value Vt for identifying whether or not the toner in the buffer unit 30 is equal to or greater than the target amount according to the output voltage Vb of the capacitance sensor 32b is used as the output of the capacitance sensor 32a. The configuration is determined based on the voltage Va.

  FIG. 9 is data showing a correspondence relationship between the output voltage Va of the capacitance sensor 32a and the threshold value Vt determined by the study of the present inventor. When the output voltage Va of the capacitance sensor 32a increases, the threshold value Vt decreases stepwise. Data indicating the correspondence between the output voltage Va of the capacitance sensor 32a and the threshold value Vt may be stored in the ROM 128 in advance.

  The CPU 120 determines the threshold value Vt from the voltage Va output from the capacitance sensor 32a by referring to data (FIG. 9) indicating the correspondence relationship between the output voltage Va and the threshold value Vt stored in advance in the ROM 128. Whether or not the output voltage Vb is less than the threshold value Vt may be identified. Thus, the CPU 120 identifies that the amount of toner in the buffer unit 30 is greater than or equal to the target amount when the output voltage Vb is greater than or equal to the threshold value Vt, and if the output voltage Vb is less than the threshold value Vt, It can be identified that the amount of toner is less than the target amount.

  Based on the output voltage Vb and the threshold value Vt, the threshold value Vt for identifying the presence or absence of toner is determined according to the result of detecting the electrostatic capacity of the toner adhering to the detection surface by the electrostatic capacity sensor 32a. Thus, the presence or absence of toner in the buffer unit 30 can be identified with high accuracy.

4 Developer 30 Buffer Unit 32a Capacitance Sensor 32b Capacitance Sensor 120 CPU

Claims (4)

Developing means for developing the electrostatic latent image formed on the photoreceptor with toner;
An accumulation container for accumulating toner for replenishing the developing means;
A first signal is provided on the wall surface of the storage container and outputs a first signal corresponding to the amount of toner between the first detection surface and the first distance in a direction orthogonal to the first detection surface. 1 output means;
Depending on the amount of toner provided on the wall surface of the storage container and in a direction perpendicular to the second detection surface and between the second detection surface and a second distance longer than the first distance. Second output means for outputting a second signal;
Storage means for storing data indicating a correspondence relationship between the first signal and a correction value for correcting the second signal;
If the difference between the correction value determined based on the first signal and the data and the second signal is greater than or equal to a specified value, the amount of toner accumulated in the accumulation container is greater than or equal to a target amount. An image forming apparatus comprising: an identification unit that identifies that the toner amount is less than the predetermined value, and identifies that the amount of toner accumulated in the accumulation container is less than a target amount. Developing means for developing the electrostatic latent image formed on the photoreceptor with toner;
An accumulation container for accumulating toner for replenishing the developing means;
A first signal is provided on the wall surface of the storage container and outputs a first signal corresponding to the amount of toner between the first detection surface and the first distance in a direction orthogonal to the first detection surface. 1 output means;
Depending on the amount of toner provided on the wall surface of the storage container and in a direction perpendicular to the second detection surface and between the second detection surface and a second distance longer than the first distance. Second output means for outputting a second signal;
Storage means storing data indicating a correspondence relationship between the first signal and a threshold value for determining that toner should be supplied to the storage container;
If the second signal is equal to or greater than a threshold value determined based on the first signal and the data, it identifies that the amount of toner accumulated in the accumulation container is equal to or greater than a target amount, and An image forming apparatus comprising: identification means for identifying that the amount of toner stored in the storage container is less than the target amount if the signal of 2 is less than the threshold value. The first output means has a first electrode and a second electrode opposite to the first electrode, and has a capacitance between the first electrode and the second electrode. Outputting the first signal based on:
The second output means includes a third electrode and a fourth electrode facing the third electrode, and has a capacitance between the third electrode and the fourth electrode. The second signal is output based on the second signal, and a distance between the third electrode and the fourth electrode is wider than a distance between the first electrode and the second electrode. Item 3. The image forming apparatus according to Item 1 or 2. Each of the first electrode and the second electrode has a configuration in which a plurality of electrodes are formed in a comb shape so that the first electrode and the second electrode do not overlap each other. Each of the first electrodes and each of the second electrodes are alternately arranged, and each of the third electrode and the fourth electrode includes a plurality of electrodes. The electrodes are formed in a comb-teeth shape so that the third electrode and the fourth electrode do not overlap each other, and each of the third electrodes and the fourth electrode The image forming apparatus according to claim 3, wherein the electrodes are arranged so as to be alternately positioned.

Images