Image forming apparatus

Abstract

In a configuration that acquires toner level information using a capacitive method, the accuracy of the acquired toner level information is maintained regardless of component variations or environmental changes. [Solution] The image forming apparatus 100 is configured such that when the stirring operation by the stirring member 63 is performed, the signal output by the output unit 80 is designated as the first signal, the acquired value based on the first signal is designated as the first acquired value, and when the stirring operation is not performed, the signal output by the output unit 80 is designated as the second signal. The adjustment unit 123 adjusts at least one of the adjustment unit 86 and the voltage application unit 70 so that the intensity of the second signal falls within a predetermined range, and the notification unit 50 notifies information regarding the remaining toner amount according to the first acquired value based on the first signal output by the output unit 80, which is in a state where the adjustment has been performed and the second signal falls within the predetermined range.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus using an electrophotographic method.

Background Art

[0002] An image forming apparatus using the electrophotographic method forms an image on a recording material by transferring a toner image formed on the surface of a photosensitive drum using a developer such as toner onto a transfer material such as paper. In such an image forming apparatus, a configuration including a toner storage unit that stores toner and toner amount detection means that detects the amount of toner inside the toner storage unit (here, also referred to as "remaining toner amount") is known.

[0003] Patent Document 1 discloses capacitance-type toner amount detection means. A stirring rod composed of two wire members is arranged in the toner storage unit to form a capacitance. When the stirring rod rotates, the state of having toner and the state of not having toner between the two wire members are repeated, and the capacitance changes. This change in capacitance is converted into a voltage by a capacitance detection unit and monitored. The monitored voltage becomes a pulse having the same period as the rotation period of the stirring rod, and by detecting the duty of this pulse, the amount of toner inside the toner storage unit can be detected. Note that the duty of the pulse and the toner amount are correlated.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In configurations that detect toner volume using a capacitive method, the following challenges exist: Variations in the distance and area of ​​the opposing electrodes, electrode resistance, stray capacitance, and the capacitance detection unit, as well as significant influences from environmental changes such as temperature and humidity, can cause the pulse voltage level to fall outside the detection range. In such cases, the accuracy of toner volume detection may decrease, or the toner volume may not be detected at all.

[0006] Therefore, the objective of the present invention is to maintain the accuracy of the toner level information obtained in a configuration that acquires toner level information using a capacitive method, regardless of variations in components or changes in the environment. [Means for solving the problem]

[0007] The above objective is achieved by the image forming apparatus according to the present invention. In summary, according to the present invention, a developing apparatus having a roller for carrying toner, a storage section for storing toner to be carried on the roller, a first electrode and a second electrode facing each other in the storage section, and a stirring member for stirring the toner in the storage section, the stirring member rotating so as toner is supplied between the first electrode and the second electrode, and a device body on which the developing apparatus is mounted, comprising a voltage application unit for applying an AC voltage to the first electrode and the second electrode, an output unit for outputting a signal corresponding to the capacitance between the first electrode and the second electrode, an adjustment unit for adjusting at least one of the output unit and the voltage application unit, an acquisition unit for acquiring an acquired value based on the signal, and information regarding the remaining amount of toner in the storage section according to the acquired value. An image forming apparatus is provided, comprising: an apparatus body having an alerting unit for providing notifications; and a control unit for controlling the voltage application unit, the output unit, the adjustment unit, and the acquisition unit; wherein the signal output by the output unit when the stirring operation by the stirring member is being performed is designated as a first signal, the acquired value based on the first signal is designated as a first acquired value, and the signal output by the output unit when the stirring operation is not being performed is designated as a second signal; the adjustment unit adjusts at least one of the output unit and the voltage application unit so that the intensity of the second signal falls within a predetermined range; and the alerting unit provides notifications according to the first acquired value based on the first signal output by the output unit when the adjustment has been performed and the second signal falls within the predetermined range. [Effects of the Invention]

[0008] According to the present invention, in a configuration that acquires information on the remaining toner amount using a capacitive method, the accuracy of the acquired information on the remaining toner amount can be maintained regardless of variations in components or changes in the environment. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing the schematic configuration of an image forming apparatus. [Figure 2]This is a cross-sectional view showing the schematic configuration of a developing apparatus. [Figure 3] This is a schematic diagram showing the toner level detection configuration. [Figure 4] This is a graph showing the relationship between capacitance C and output voltage Vsns, and an explanatory diagram showing the waveform of the output voltage Vsns of the capacitance detection unit. [Figure 5] This is a schematic diagram illustrating a table showing the relationship between duty cycle and remaining toner. [Figure 6] This is a schematic diagram showing the output voltage waveform of the capacitance detection unit to explain the conversion to Hi / Lo pulse signals. [Figure 7] This is a flowchart illustrating the procedure for adjusting and controlling the output voltage Vsns. [Figure 8] This is a schematic diagram showing the output voltage waveform of the capacitance detection unit to explain the procedure for adjusting and controlling the output voltage Vsns. [Figure 9] This is a schematic diagram showing the output voltage waveform of the capacitance detection unit, illustrating how to set the abnormality detection threshold voltage. [Figure 10] This graph illustrates the anomaly detection range in the examples and comparative examples. [Figure 11] This is a schematic diagram illustrating another example of an image forming apparatus. [Modes for carrying out the invention]

[0010] The image forming apparatus according to the present invention will be described in more detail below with reference to the drawings.

[0011] [Example 1] <Configuration of an image forming apparatus> Figure 1 is a cross-sectional view showing the schematic configuration of the image forming apparatus 100 in this embodiment. In this embodiment, the image forming apparatus 100 is a laser beam printer as an example of an image forming apparatus using an electrophotographic process. Note that the image forming apparatus using an electrophotographic process may be, for example, a copier, a printer, a facsimile machine, or a multifunction device that has several of these functions.

[0012] The apparatus main body 101 of the image forming apparatus 100 has a paper feed cassette 104 for storing a recording material (recording medium, transfer material, sheet) S such as paper or a plastic sheet. Further, the apparatus main body 101 has a paper feed roller 141 for feeding out the recording material S from the paper feed cassette 104, and a pair of conveyance rollers 142 for conveying the recording material S fed out by the paper feed roller 141. Further, the apparatus main body 101 has a top sensor 143 for detecting the leading end of the recording material S and a pair of registration rollers 144 for synchronously conveying the recording material S downstream of the pair of conveyance rollers 142 in the conveyance direction of the recording material S.

[0013] Then, the apparatus main body 101 has a cartridge unit (process cartridge) 15 downstream of the pair of registration rollers 144 in the conveyance direction of the recording material S. The cartridge unit 15 is detachable from the apparatus main body 101. The cartridge unit 15 has a photosensitive drum 48 as an image carrier, a primary charging roller 47, a developing device 41, a cleaning device 42, and the like. Further, the apparatus main body 101 has a laser scanner 106 above the cartridge unit 15 in the drawing. Further, the apparatus main body 101 has a transfer roller 145 disposed below the cartridge unit 15 in the drawing so as to contact the photosensitive drum 48.

[0014] The photosensitive drum 48 rotates in the direction of arrow A1 (clockwise direction) in the drawing. The surface of the rotating photosensitive drum 48 is uniformly charged by the primary charging roller 48. The charged surface of the photosensitive drum 48 is scanned and exposed by the laser light from the laser scanner 106, and an electrostatic latent image (electrostatic image) is formed on the photosensitive drum 48. The electrostatic latent image formed on the photosensitive drum 48 is developed by supplying toner as a developer by the developing device 41, and a toner image is formed on the photosensitive drum 48. The toner image formed on the photosensitive drum 48 is transferred onto the recording material S at the transfer portion where the photosensitive drum 48 and the transfer roller 145 contact. The toner remaining on the photosensitive drum 48 without being transferred onto the recording material S is removed and recovered from the photosensitive drum 48 by the cleaning device 42.

[0015] [[ID=*12]] The apparatus main body 101 has a heat fuser 103 for thermally fixing the toner image formed on the recording material S onto the recording material S downstream of the cartridge unit 15 in the conveyance direction of the recording material S. The heat fuser 103 includes a fixing film 149, a pressure roller 150, a heater 102 disposed on the inner peripheral surface side of the fixing film 149, and a thermistor 109 for detecting the temperature of the heater 102. The thermistor 109 is disposed in the vicinity of the heater 102 on the inner peripheral surface side of the fixing film 149 so as to detect the temperature of the heater 102. Further, the apparatus main body 101 has a paper discharge roller pair 151 downstream of the heat fuser 103 in the conveyance direction of the recording material S.

[0016] The recording material S onto which the toner image is transferred is conveyed to the heat fuser 103. The heat fuser 103 heats and presses the recording material S in a fixing portion where the fixing film 149 and the pressure roller 150 are in contact with each other, thereby thermally fixing the toner image onto the recording material S. The recording material S onto which the toner image is fixed is discharged (output) to a discharge portion provided at the upper part in the drawing of the apparatus main body 101 by the paper discharge roller pair 151.

[0017] Also, the apparatus main body 101 has a power supply unit (power supply device) 120. The power supply unit 120 can appropriately switch and output a voltage of 24V or a voltage of 10V, and generates a voltage of 24V in the print mode or the standby mode. Then, the power supply unit 120 supplies a voltage of 24V as a drive system voltage to each part of the image forming apparatus 100 via an engine controller 123 described later. Examples of such each part include a drive unit 40 provided with a motor, a clutch, etc., a high voltage power supply (not shown) for supplying a high voltage to the cartridge unit 15, a polygon mirror drive unit (not shown) of the laser scanner 106, and the like.

[0018] Furthermore, the main unit 101 has an engine controller 123 that controls the main unit 101. The engine controller 123 controls the transport of the recording material S by operating various rollers through the drive unit 40. The engine controller 123 also controls the laser scanner 106, cartridge unit 15, heat fuser 103, etc., by controlling the drive unit 40. In this way, the engine controller 123 can cause the image forming apparatus 100 to perform image forming (hereinafter also referred to as "printing"). The engine controller 123 also has a DC-DC converter 121 built inside it, which generates a voltage of 3.3V mainly used in the control system based on the voltage supplied from the power supply unit 120. This voltage of 3.3V is supplied to the control circuit (not shown) built inside the engine controller 123, as well as the control system circuit including the video controller 131 (described later), the laser light-emitting part of the laser scanner 106 (not shown), and the top sensor 143.

[0019] Furthermore, the main unit 101 has a video controller 131. The video controller 131 is connected to the engine controller 123 by an engine interface 133 and is also connected to an external device 132 such as a personal computer by a general-purpose external interface 134 (such as USB).

[0020] The video controller 131 receives print information (such as the number of copies and various settings) and print data from the external interface 134. The video controller 131 has an image control unit (not shown) inside it, which converts the print data received from the external interface 134 into image data that can be printed by the image forming apparatus 100. Subsequently, the engine controller 123 receives the image data from the video controller 131 via the engine interface 133 at a predetermined timing and sends it to the laser scanner 106.

[0021] In this embodiment, the engine controller 123 has the functions of an adjustment unit that adjusts at least one of the output unit (capacitance detection unit) 80 and the voltage application unit (AC voltage output unit) 70, and an acquisition unit that acquires an acquired value (toner level) based on the signal output by the output unit 80, as will be described later.

[0022] Furthermore, the image forming apparatus 100 has an openable and closable door 43 that opens the interior of the image forming apparatus 100 and allows access to the interior of the image forming apparatus 100. Accessing the interior of the image forming apparatus 100 includes, for example, the operator putting their hand inside the image forming apparatus 100 to replace the cartridge unit 15 or to deal with a jam (paper jam), or the operator checking (visually inspecting) the interior of the image forming apparatus 100 to check the installation status of the cartridge unit 15 or whether there is a jam.

[0023] <Developing equipment> Figures 2(a) and 2(b) are cross-sectional views showing the schematic configuration of the developing apparatus 41 in this embodiment. Figures 2(a) and 2(b) schematically show the state when the amount of toner (remaining toner) inside the toner storage section 60, which will be described later, becomes low. In this embodiment, when the remaining toner becomes low, for example, when the remaining toner amount falls to 30% or less, with the initial (unused) toner amount being 100%.

[0024] The developing device 41 includes a toner storage section 60, which is a storage section for toner T, and a developing roller 46, which is a developing member that supplies the toner T stored in the toner storage section 60 to the photosensitive drum 48. The developing roller 46 rotates in the direction of arrow A2 in the figure (counterclockwise), carrying the toner T stored in the toner storage section 60 on its surface, and transporting it to the developing section that comes into contact with the photosensitive drum 48, supplying toner to the electrostatic latent image on the photosensitive drum 48.

[0025] Furthermore, inside the toner storage section 60 are a first electrode 61 and a second electrode 62, which are conductive members constituting the capacitance section 64, and an agitation member 63. The first electrode 61 and the second electrode 62 are mounted facing each other in a recess 60a provided in the toner storage section 60, which is recessed from the inside outwards. The first electrode 61 and the second electrode 62 are fixed to the inner wall (wall surface) of the toner storage section 60 that constitutes the recess 60a. The agitation member 63 has a shaft portion 63a that can rotate about a rotation axis that extends substantially parallel to the rotation axis of the photosensitive drum 48 and the developing roller 46, and a sheet-shaped agitation portion (agitating blade) 63b fixed to the shaft portion 63a. The agitation member 63 rotates in the direction of arrow A3 (clockwise direction) in the figure to agitate the toner T. The developing roller 46 and the agitation member 63 of the developing device 41 are rotated by driving force transmitted from the drive unit 40. The stirring member 63 stirs the toner T inside the toner storage section 60 by a periodic stirring motion. In this embodiment, the periodic stirring motion of the toner T inside the toner storage section 60 by the stirring member 63 is a rotational motion, but it may also be a reciprocating motion or an oscillating motion.

[0026] Figure 2(a) shows the state in which the toner T is at the bottom of the toner storage section 60. In this state, the toner detection section 65, which is the space between the first electrode 61 and the second electrode 62 that constitute the capacitance section 64, is not filled with toner T. On the other hand, Figure 2(b) shows the state in which the toner T has been lifted by the stirring member 63 and the toner detection section 65 is filled with toner T. Thus, the developing device 41 can take on a first state in which the toner T stirred by the stirring member 63 fills the space of the toner detection section 65, and a second state in which it does not. The developing device 41 can also take on intermediate states in the transition from the state in which the toner detection section 65 is filled with toner T to the state in which it is not filled, and intermediate states in the transition from the state in which the toner detection section 65 is not filled with toner T to the state in which it is filled.

[0027] Hereinafter, the first state in which the toner detection unit 65 is not filled with toner, as shown in Figure 2(a), will also be referred to as the "state where there is no toner in the toner detection unit 65," and the second state in which the toner detection unit 65 is filled with toner, as shown in Figure 2(b), will also be referred to as the "state where there is toner in the toner detection unit 65." Let CO be the capacitance of the capacitance unit 64 in the state where there is no toner in the toner detection unit 65, and CI be the capacitance of the capacitance unit 64 in the state where there is toner in the toner detection unit 65, and let εr be the relative permittivity of air and toner T. At this time, the relationship expressed by the following equation (1) holds.

[0028] CI = εrCO···(1)

[0029] As shown in Figures 2(a) and (b), when the toner level is low, the change in capacitance of the capacitance unit 64 is repeated at the rotational cycle of the stirring member 63 (hereinafter referred to as the "rotational cycle" or "stirring cycle") while the stirring member 63 is rotating.

[0030] <Detecting remaining toner level> Next, the detection of toner level in this embodiment will be described. Figure 3 is a schematic diagram showing the toner level detection configuration in this embodiment. In this embodiment, the image forming apparatus 100 detects the toner level using a capacitance detection unit 80, which is an example of a capacitance-type toner level detection means.

[0031] As shown in Figure 3, the toner level detection configuration comprises a toner storage unit 60, an engine controller 123, an AC voltage output unit 70, and a capacitance detection unit 80. The capacitance detection unit 80 includes rectifier diodes 81 and 82, a detection resistor 83, a rectifier capacitor 84, an operational amplifier 85, and a DC power supply 86 that outputs a reference voltage Vref. The capacitance detection unit 80 is connected to the capacitance unit 64 and the CPU 124, which is a control unit provided in the engine controller 123, and detects the voltage Vsns, which will be described later, using an AD converter 125 provided inside the CPU 124. In this embodiment, the detection range of the AD converter 125 is assumed to be 0V to 3.3V. Note that "~" in the numerical range means that the values ​​before and after it are included. The AC voltage output unit 70 constitutes a voltage application unit that applies an AC voltage to the first electrode 61 and the second electrode 62. The CPU 124 can variably control the values ​​of Vpp (peak voltage), frequency f, and reference voltage Vref of the AC voltage (hereinafter referred to as "residual detection AC voltage") output from the AC voltage output unit 70, which are parameters that determine the output characteristics of the capacitance detection unit 80.

[0032] The remaining AC voltage is applied to the capacitance section 64, and an alternating current (AC) current corresponding to the capacitance of the capacitance section 64 flows through the capacitance section 64. This AC current is rectified by the rectifier diodes 81 and 82 and the rectifier capacitor 84. The reference voltage Vref, which is a DC voltage input from the DC power supply 86, is applied to the non-inverting input terminal (hereinafter referred to as the "+ terminal") of the operational amplifier 85. The inverting input terminal (hereinafter referred to as the "- terminal") of the operational amplifier 85 is in an imaginary short-circuit relationship with the + terminal, and therefore maintains a state of approximately the same potential as the + terminal. The voltage Vsns input from the capacitance detection section 80 to the CPU 124 is the voltage value obtained by the voltage drop from the voltage at the - terminal of the operational amplifier 85 (reference voltage Vref) by the amount of the DC current that flowed through the detection resistor 83. Specifically, the rectifier diodes 81 and 82, the rectifier capacitor 84, the operational amplifier 85, the DC power supply 86, and the sensing resistor 83 output a voltage Vsns corresponding to the current input from the capacitance unit 64. Therefore, these function as conversion units that modify the detection result of the capacitance sensing unit 80. The capacitance sensing unit 80 also has a resistor 88 and a capacitor 87 in the input path of the voltage Vsns to the CPU 124 for signal stabilization and other purposes.

[0033] The current I flowing through the sensing resistor 83 is equal to the current flowing through the capacitance section 64. The charge Q stored in the capacitance C of the capacitance section 64 is given by Q = C × V, where V is the voltage applied to the cathode side of the rectifier diode 81. Also, Q = ∫I(t)dt, and from these relationships, the current I flowing through the sensing resistor 83 can be determined. The current I flowing through the sensing resistor 83 is given by the following equation (2), where C is the capacitance of the capacitance section 64, VPP and f are the amplitude voltage and frequency of the residual AC voltage, Vref is the voltage of the DC power supply 86 (reference voltage), and VF is the forward voltage of the rectifier diodes 81 and 82.

[0034] I = Cf(VPP - Vref - 2VF) ... (2)

[0035] Alternatively, the resistance value of the sensing resistor 83 can be denoted as R, and the result can be expressed by the following equation (3).

[0036] I = (Vref - Vsns) / R ... (3)

[0037] Eliminating I from equations (2) and (3) and rearranging, we obtain equation (4).

[0038] C=(Vref-Vsns) / {Rf(VPP-Vref-2VF)}···(4)

[0039] Therefore, by configuring the system as shown in Figure 3, the CPU 124 can detect changes in the capacitance C of the capacitance unit 64 as changes in the voltage (hereinafter referred to as "output voltage") Vsns output from the capacitance detection unit 80. The capacitance detection unit 80 is configured as an output unit that outputs a signal corresponding to the capacitance between the first electrode 61 and the second electrode 62.

[0040] Figure 4 is an explanatory diagram showing a graph illustrating the relationship between the capacitance C of the capacitance unit 64 and the output voltage Vsns shown in equation (4), and the waveform of the output voltage Vsns of the capacitance detection unit 80. In the graph of Figure 4, the horizontal axis represents capacitance C [pF], and the vertical axis represents output voltage Vsns [V]. As shown by the dashed line in the figure, the detection range of the output voltage Vsns is determined by the capacitance CO when there is no toner T in the toner detection unit 65 and the capacitance CI when there is toner T in the toner detection unit 65. Here, let VO be the output voltage Vsns when the capacitance C of the capacitance unit 64 is capacitance CO when there is no toner T in the toner detection unit 65, and let VI be the output voltage Vsns when the capacitance C of the capacitance unit 64 is capacitance CI when there is toner T in the toner detection unit 65.

[0041] The waveform shown on the right side of the graph in Figure 4 is the waveform of the output voltage Vsns of the capacitance detection unit 80 while the stirring member 63 is rotating. This waveform is obtained by the CPU 124 by converting the output voltage Vsns (hereinafter referred to as "Vsns_AD") detected by the AD converter 125 into a Hi / Lo pulse signal, with the horizontal axis representing time and the vertical axis representing the output voltage Vsns. The period of this waveform is the rotation period Tp of the stirring member 63, and the amplitude is the detection range of the output voltage Vsns (VI≦Vsns≦VO). The ratio of time TO when there is no toner T in the toner detection unit 65 to time TI when there is toner T in the toner detection unit 65 correlates with the remaining amount of toner T inside the toner storage unit 60. The CPU 124 measures time TO and TI using a timer provided inside the CPU 124, triggered by the edge of the Hi / Lo pulse signal. The CPU 124 then calculates the ratio of the rotation period Tp to the time TI during which toner T is present (hereinafter referred to as the "duty cycle"), i.e., TI / (TO+TI). Based on the calculated duty cycle (TI / (TO+TI)), the CPU 124 detects the remaining toner amount by referring to a table stored in the memory unit 126 beforehand, which represents the relationship between the duty cycle and the remaining toner amount. In this way, the CPU 124 determines the amount of toner T in the toner storage unit 60 based on the voltage waveform output by the capacitance detection unit 80. More specifically, the CPU 124 detects the remaining toner amount based on the voltage waveform output when the toner T stirred by the stirring member 63 fills the toner detection unit 65, and the voltage waveform output when the toner detection unit 65 does not fill the toner. The CPU 124 may start timer-based measurement triggered by the rising edge of the Hi / Lo pulse signal, or it may start timer-based measurement triggered by the falling edge of the Hi / Lo pulse signal. Additionally, CPU124 may perform timer measurements triggered by the rising and falling edges of Vsns_AD before it is converted into a Hi / Lo pulse signal.

[0042] <Toner level detection and control> Next, an example of the control for detecting the remaining toner amount in this embodiment (hereinafter referred to as "toner amount detection control") will be described. Figure 5 is a schematic diagram showing an example of a table representing the relationship between the duty cycle (TI / (TO+TI)) and the remaining toner amount, which is pre-stored in the memory unit 126. In the table in Figure 5, the first column shows the duty cycle [%] and the second column shows the remaining toner amount [%]. For example, if the calculated duty cycle is 70%, the CPU 124 will detect the remaining toner amount as 30% by referring to the table in Figure 5. The CPU 124 controls the system to notify the user of the detected remaining toner amount by displaying it on, for example, the display unit 50 provided in the image forming apparatus 100. Here, a specific example of calculating the remaining toner amount using the table in Figure 5 will be shown. Assume that the time when there is no toner T in the toner detection unit 65 is TO = 0.6 [sec], and the time when there is toner T in the toner detection unit 65 is TI = 0.4 [sec]. The CPU 124 calculates the duty cycle (TI / (TO+TI)) as 40% and detects the toner level as 15% by referring to the table in Figure 5. The CPU 124 controls the display unit 50 to notify the toner level as 15%. The engine controller 123 constitutes an acquisition unit that acquires the toner level as an acquired value based on the signal output by the capacitance detection unit 80. The display unit 50 also constitutes a notification unit that notifies information regarding the toner level in the toner storage unit 60.

[0043] The CPU 124 may, in addition to or instead of notifying the toner level on the display unit 50 of the image forming apparatus 100, control the display unit of the external device 132 to notify the toner level. In this case, the notification unit is configured by a transmission unit, such as one provided in the engine controller 123, which transmits information regarding the toner level to the external device 132. Furthermore, the information regarding the toner level is not limited to the value of the toner level; for example, the CPU 124 may notify the user of a warning (such as a message) prompting them to replace the cartridge unit 15 when the toner level falls below a predetermined value. In addition, notification of information regarding the toner level is not limited to displaying the toner level or a message; it may also be done by generating sound from a sound-producing unit, generating light from a light-emitting unit, etc.

[0044] <Conversion of output voltage Vsns to Hi / Lo pulse signals> An example of converting Vsns_AD to Hi / Lo pulse signals will be explained using Figure 6(a). Figure 6(a) is a schematic diagram showing Vsns_AD and the Hi / Lo pulse signals converted from Vsns_AD in chronological order.

[0045] In order to convert Vsns_AD into a Hi / Lo pulse signal, a threshold voltage Vth is set between the Vsns_AD when there is no toner T in the toner detection unit 65 and the Vsns_AD when there is toner T in the toner detection unit 65, in order to distinguish between Hi and Lo. As an example of how Vth is calculated, in this embodiment, the CPU 124 samples Vsns_AD for one cycle of the stirring cycle Tp at 1 ms, takes the average of the top 5 sampled voltages as Vmax, and the average of the bottom 5 as Vmin, and calculates Vth using the following equation (5).

[0046] Vth = (Vmax - Vmin) / 2 ... (5)

[0047] For example, after the output voltage Vsns adjustment control described later, and before the start of the toner level detection control (or immediately after the start of the toner level detection control), the CPU 124 can calculate the threshold voltage Vth based on Vsns_AD acquired while the stirring member 63 is rotating. The CPU 124 stores the calculated threshold voltage Vth in the storage unit 126.

[0048] Then, CPU124 converts Vsns_AD into a Hi / Lo pulse signal, where a voltage higher than the calculated threshold voltage Vth is considered Hi, and a voltage lower than Vth is considered Lo.

[0049] <Challenges> Figure 6(a) shows an example of the Vsns_AD waveform when the parameters determining the output voltage Vsns are typical values ​​such as design values. These parameters include variations in the distance and area of ​​the electrodes facing each other that constitute the capacitance unit 64, the resistance value of the electrodes, stray capacitance, and the capacitance detection unit 80, as well as changes in the environment such as temperature and humidity. Changes in the environment such as temperature and humidity can also alter the influence of variations in the electrode resistance value, stray capacitance, and capacitance detection unit. In the case of Figure 6(a), both Vsns_AD when there is no toner T in the toner detection unit 65 and Vsns_AD when there is toner T in the toner detection unit 65 fall within the detection range of the AD converter 125, 0V to 3.3V. Therefore, the conversion to Hi / Lo pulse signals is performed normally, and the expected toner amount can be detected from the table representing the relationship between the duty cycle and the remaining toner amount, which is pre-stored in the memory unit 126.

[0050] Figure 6(b) shows an example of the Vsns_AD waveform when the resistance value or stray capacitance of the electrodes constituting the capacitance unit 64 increases due to, for example, variations in components or changes in the environment. In this case, Vsns_AD when there is no toner T in the toner detection unit 65 exceeds the upper limit of the detection range of the AD converter 125, 3.3V, as shown by the dashed line. In other words, Figure 6(b) shows a situation where Vsns_AD of 3.3V or higher cannot be detected. The table showing the relationship between the duty cycle and the remaining toner amount, which is pre-stored in the memory unit 126, assumes that Vsns_AD is within the detection range of the AD converter 125, from 0V to 3.3V. Therefore, in the case of Figure 6(b), although it would be desirable to calculate the threshold voltage Vth based on Vsns_AD shown by the dashed line, the threshold voltage Vth1 is calculated based on Vsns_AD shown by the solid line. Compared to the Hi / Lo pulse signal converted by threshold voltage Vth, the Hi / Lo pulse signal 1 converted by threshold voltage Vth1 has a longer TI time and a shorter TO time, making it difficult to accurately detect the remaining toner level. In a capacitive method that detects the remaining toner level by pulse duty cycle, it is desirable to ensure that the output voltage Vsns (Vsns_AD) falls within the detection range of the AD converter 125 (0V to 3.3V in this embodiment).

[0051] <Output Voltage Vsns Adjustment Control> Next, an example of control for adjusting the output voltage Vsns (Vsns_AD) to within the detection range of the AD converter 125 (hereinafter referred to as "output voltage Vsns adjustment control") will be described. The output voltage Vsns is the voltage value obtained by the voltage drop from the voltage at the negative terminal of the operational amplifier 85 (reference voltage Vref) by the amount of the DC current flowing through the detection resistor 83. The reference voltage Vref can be adjusted by the control voltage Vref_cont output by the CPU 124. In this embodiment, the CPU 124 adjusts the reference voltage Vref by adjusting Vref_cont so that the output voltage Vsns falls within the detection range of the AD converter 125.

[0052] In this embodiment, the output voltage Vsns adjustment control is performed when the toner T inside the toner storage unit 60 is not being agitated by the agitator 63. For example, in this embodiment, the output voltage Vsns adjustment control is performed before the start of toner level detection control, such as when the image forming apparatus 100 is powered on or during the initial operation after replacing the cartridge unit 15. In other words, in this embodiment, the output voltage Vsns adjustment control is performed before the agitation of the toner T inside the toner storage unit 60 begins. By performing the output voltage Vsns adjustment control before the start of toner level detection control, there is no need to introduce a new sequence during toner level detection control, thus reducing the downtime of toner level detection control. Furthermore, by performing the output voltage Vsns adjustment control immediately before toner level detection control, such as immediately before image formation, the output voltage Vsns can be adjusted in a timely manner to match the variation in the parameters that determine the output voltage Vsns. For example, the output voltage Vsns adjustment control can be performed during the preparation operation (pre-rotation operation) in which the photosensitive drum 48 is rotated immediately before image formation.

[0053] Thus, output voltage Vsns adjustment control can be performed during initial operation, such as when the power to the image forming apparatus 100 is turned ON or when the door 43 (Figure 1) is opened or closed for purposes such as replacing the cartridge unit 15. Initial operation is a preparatory operation (calibration operation) that is performed when no image is being formed, such as calibration operation (image density control, etc.) or hardware check, and is not being performed to transfer an image to the recording material S for output. The engine controller 123 can detect when the power to the image forming apparatus 100 is turned ON, and can also detect at least one of the opening or closing of the door 43 by the opening / closing sensor 110 (Figure 1), which is an opening / closing detection means. Furthermore, output voltage Vsns adjustment control can be performed when the photosensitive drum 38 is rotating just before image formation begins.

[0054] For example, if capacitance is configured by placing a stirring rod consisting of two conductive members in the toner storage section 60, the rotation of the stirring rod causes the toner to alternately be present between the two conductive members, resulting in an amplitude fluctuation in the output voltage Vsns. In such a configuration, the same effect as described above can be obtained by performing output voltage Vsns adjustment control before the stirring rod rotates.

[0055] An example of the procedure for adjusting the output voltage Vsns will be explained using Figures 7 and 8. Figure 7 is a flowchart illustrating the procedure for adjusting the output voltage Vsns. Figure 8 is a schematic diagram showing an example of the waveform of the output voltage Vsns of the capacitance detection unit 80 for illustrating the procedure for adjusting the output voltage Vsns, and shows each signal in chronological order from the start of the output voltage Vsns adjustment control to the start of the toner remaining amount detection control. Step numbers S301 to S304 in Figures 7 and 8 indicate corresponding timings.

[0056] When CPU124 starts adjusting the output voltage Vsns, it outputs cont1 (initial value), which is a pre-set Vref_cont (S301). As a result, the reference voltage Vref corresponding to cont1 is input to the + terminal of op-amp 85. At this time, since no residual AC voltage is output, the output voltage Vsns is the same voltage as the reference voltage Vref, and Vsns_AD becomes 3.3V.

[0057] Next, the CPU 124 turns on the output of the remaining AC voltage (S302). When the output of the remaining AC voltage is turned on, current flows through the detection resistor 83, and the CPU 124 detects AD1, which is Vsns_AD, obtained by the voltage drop from the reference voltage Vref by the amount of the DC current that flowed through the detection resistor 83. When the CPU 124 detects AD1, it determines whether Vsns_AD is within a predetermined range (S303). In this embodiment, this predetermined range is set to 1.5V to 1.8V. An example of how to set this predetermined range will be explained in the next section.

[0058] If Vsns_AD is within the range of 1.5V to 1.8V, CPU124 terminates the output voltage Vsns adjustment control and moves to toner level detection control. On the other hand, if Vsns_AD is not within the range of 1.5V to 1.8V, CPU124 changes the setting of Vref_cont as follows (S304). That is, based on the value of Vsns_AD, it calculates Vref_cont so that Vsns_AD is a value between 1.5V and 1.8V, and changes the setting of Vref_cont. Figure 8 shows an example where the value of AD1 is not within the range of 1.5V to 1.8V. As shown in Figure 8, based on the value of AD1, Vref_cont so that Vsns_AD is a value between 1.5V and 1.8V is calculated, and the setting of Vref_cont is changed to the calculated cont2. When the CPU 124 changes the setting of Vref_cont to cont2, it re-checks whether Vsns_AD is within the range of 1.5V to 1.8V (S303). Figure 8 shows an example where setting Vref_cont to cont2 detects AD2, which is Vsns_AD within the range of 1.5V to 1.8V. Subsequently, the CPU 124 executes the toner level detection control with the setting that Vsns_AD is AD2 (Vref_cont=cont2). The CPU 124 may also determine that there is an abnormality if AD2 is not within the predetermined range of 1.5V to 1.8V, or if it deviates significantly from the predetermined range of 1.5V to 1.8V by a predetermined value. In that case, the CPU 124 may execute processing such as notifying the display unit 50 or external device 132 that it will not proceed to the toner level detection control, or that the toner level detection control will not be performed properly.

[0059] <Setting a predetermined range for the output voltage Vsns> Next, an example of how to set a predetermined range for the output voltage Vsns will be described. In this embodiment, the predetermined range for the output voltage Vsns is set to 1.5V to 1.8V, which is a range that takes into account a variation of ±0.15V from 1.65V, the median value of the detection range 0V to 3.3V of the AD converter 125.

[0060] First, the purpose of the output voltage Vsns adjustment control is to keep the output voltage Vsns when there is no toner T in the toner detection unit 65 and the output voltage Vsns when there is toner T in the toner detection unit 65 within the detection range of the AD converter 125, which is 0V to 3.3V. During the execution of toner level detection control, the output voltage Vsns may fluctuate due to external noise or changes in the environment such as temperature and humidity. Therefore, it is desirable to set a predetermined range of the output voltage Vsns to include the median value of the detection range of the AD converter 125, which is 0V to 3.3V, and to bring the output voltage Vsns closer to the median value of the detection range of the AD converter 125. This makes it possible to suppress the output voltage Vsns from falling outside the detection range of the AD converter 125, even if the output voltage Vsns fluctuates during the execution of toner level detection control. The voltage range relative to the median value can be set appropriately, for example, taking into account calculation errors and component variations. In this embodiment, the number of repetitions of processes S303 and S304 in Figure 8 can be sufficiently reduced, and the output voltage Vsns is set to a value that sufficiently suppresses the occurrence of the toner level detection control falling outside the detection range of the AD converter 125.

[0061] Furthermore, in this embodiment, the state of the toner detection unit 65 when performing output voltage Vsns adjustment control may be filled with toner or empty, and the amount of toner T in the toner detection unit 65 is not constant. Therefore, the output voltage Vsns after performing output voltage Vsns adjustment control will be a value between the voltage when there is no toner T in the toner detection unit 65 (VO in Figure 4) and the voltage when there is toner T in the toner detection unit 65 (VI in Figure 4). Let ΔV be the difference between VO and VI in Figure 4, and let V2 be the output voltage Vsns adjusted by the output voltage Vsns adjustment control. In this case, if the output voltage Vsns adjustment control is performed when there is no toner T in the toner detection unit 65, the output voltage Vsns during toner remaining amount detection control will oscillate in the range of V2 to V2-ΔV. On the other hand, if the output voltage Vsns adjustment control is performed when there is toner T in the toner detection unit 65, the output voltage Vsns during toner remaining amount detection control will oscillate in the range of V2 to V2+ΔV. Therefore, the amplitude range of the output voltage Vsns during toner level detection control changes depending on the state of the toner detection unit 65 when the output voltage Vsns adjustment control is performed. For this reason, it is desirable to set a predetermined range of the output voltage Vsns to include the midpoint of the detection range 0V to 3.3V of the AD converter 125, and to bring the output voltage Vsns closer to the midpoint of the detection range 0V to 3.3V of the AD converter 125. This makes it possible to ensure that the output voltage Vsns during toner level detection control falls within the detection range 0V to 3.3V of the AD converter, regardless of the amount of toner T in the toner detection unit 65.

[0062] From the above perspective, it is preferable to set the predetermined range of the output voltage Vsns to a predetermined voltage range that takes into account calculation errors and component variations, as described above, relative to the median value of the detection range of the AD converter 125. However, if it is known in advance that the voltage fluctuation of the output voltage Vsns due to disturbance noise will fluctuate to the higher side, measures such as setting the predetermined range of the output voltage Vsns lower than the median value of the detection range of the AD converter 125 may be taken as a countermeasure against such disturbance noise. Furthermore, ensuring that the output voltage Vsns falls within the predetermined range includes setting the output voltage Vsns to a predetermined value, such as the median value of the detection range of the AD converter 125.

[0063] In this embodiment, by adjusting the output voltage Vsns to a value within the range of 1.5V to 1.8V, the output voltage Vsns can be kept within the detection range of the AD converter 125 even when there is a large variation in the parameters that determine the output voltage Vsns.

[0064] In this embodiment, Vref_cont is adjusted only once, from cont1 to cont2, but Vref_cont may be adjusted multiple times. For example, the amount of change in the Vref_cont setting each time may be set to a predetermined range, and the process of determining whether the output voltage Vsns is within a predetermined range and changing the Vref_cont setting may be repeated.

[0065] In this embodiment, the output voltage Vsns is adjusted by variably controlling the reference voltage Vref. However, the output voltage Vsns may be adjusted by other means, such as variably controlling the residual AC voltage Vpp, frequency f, or the detection resistor 83. In other words, the engine controller 123 can shift the output level of the capacitance detection unit 80 by variably controlling the reference voltage Vref, which is compared with a voltage corresponding to the current flowing through the first electrode 61 and the second electrode 62, thereby adjusting the output voltage Vsns of the capacitance detection unit 80. Furthermore, the engine controller 123 can shift the output level of the capacitance detection unit 80 by variably controlling at least one of the residual AC voltage Vpp or frequency f to change the gain in the AC voltage output unit 70. This is because changing at least one of the residual AC voltage Vpp or frequency f can change the current flowing through the first electrode 61 and the second electrode 62 to the detection resistor 83. Furthermore, the engine controller 123 can shift the output level of the capacitance detection unit 80 by variably controlling the resistance value of the detection resistor 83 to change the gain in the capacitance detection unit 80. The output level of the capacitance detection unit 80 can be adjusted by variably controlling at least one of the following: the reference voltage Vref, the residual AC voltage Vpp, the frequency of the residual AC voltage, and the resistance value of the detection resistor 83. Two or more of these may be arbitrarily combined and variably controlled.

[0066] Furthermore, in this embodiment, the capacitance detection unit 80 is configured to convert the current flowing through the capacitance unit 64 into a voltage using an I / V conversion circuit having an operational amplifier 85. However, the capacitance detection unit can be configured to output a voltage or current corresponding to the capacitance of the capacitance unit 64. For example, the current flowing through the capacitance unit 64 may be directly input to the engine controller 123. In this case, the engine controller 123 may also perform at least a part of the function of the capacitance detection unit 80.

[0067] Furthermore, in this embodiment, the cartridge unit 15 is detachable from the main body 101 of the device, and for example, when the amount of toner remaining in the toner storage unit 60 falls below a predetermined value, the cartridge unit 15 is replaced. However, the present invention is not limited to this embodiment. The image forming apparatus 100 may be configured to replenish toner in the toner storage unit 60. For example, as shown in Figure 11, the image forming apparatus 100 may be configured such that the developing unit 41 is provided with a replenishment port 66 for replenishing toner, and a toner cartridge 44, which is a replenishment container, is connected to this replenishment port 66. For example, when the amount of toner remaining in the toner storage unit 60 falls below a predetermined value, the toner cartridge 44 is connected to the replenishment port 66, and toner is replenished in the toner storage unit 60. The image forming apparatus 100 may be configured to perform image forming after the toner cartridge 44 is removed after toner replenishment, or it may be configured to perform image forming with the toner cartridge 44 installed. In the former case, the toner cartridge 44 is attached to and detached from the developing unit 41 when toner is replenished. In the latter case, toner replenishment may be performed all at once immediately after the toner cartridge 44 is installed (replaced) in the developing unit 41, or it may be performed sequentially according to the consumption of toner in the toner storage unit 60.

[0068] Thus, in this embodiment, the image forming apparatus 100 is a developing apparatus 41 comprising a roller (developing roller) 46 for carrying toner, a storage section (toner storage section) 60 for storing toner to be carried on the roller 46, a first electrode 61 and a second electrode 62 facing each other in the storage section 60, and a stirring member 63 for stirring the toner in the storage section 60, the stirring member 63 rotating so that toner is supplied between the first electrode 61 and the second electrode 62. Furthermore, the image forming apparatus 100 is a device body 101 on which a developing apparatus 41 is mounted, and comprises a voltage application unit (AC voltage output unit) 70 that applies an AC voltage to a first electrode 61 and a second electrode 62, an output unit (capacitance detection unit) 80 that outputs a signal corresponding to the capacitance between the first electrode 61 and the second electrode 62, an adjustment unit (engine controller) 123 that adjusts at least one of the output unit 80 and the voltage application unit 70, an acquisition unit (engine controller) 123 that acquires an acquired value (toner amount) based on the above signal, an announcement unit (display unit) 50 that notifies information regarding the toner amount in the storage unit 60 according to the above acquired value, and a control unit (CPU) 124 that controls the voltage application unit 70, the output unit 80, the adjustment unit 123 and the acquisition unit 123. Furthermore, when the stirring operation by the stirring member 63 is performed, the signal output by the output unit 80 is designated as the first signal, the acquired value based on the first signal is designated as the first acquired value, and when the stirring operation is not performed, the signal output by the output unit 80 is designated as the second signal. In this embodiment, the adjustment unit 123 adjusts at least one of the output unit 80 and the voltage application unit 70 so that the intensity of the second signal falls within a predetermined range, and the notification unit 50 provides notification according to the first acquired value based on the first signal output by the output unit 80, which is in a state where the adjustment has been performed and the second signal falls within the predetermined range. In this embodiment, the first acquired value is a value based on the duty cycle of the first signal. In this embodiment, the developing device 41 is detachable from the main body 101. However, the image forming apparatus 100 may be provided with a toner supply port 66 in the storage unit 60 for supplying toner.

[0069] In this embodiment, the predetermined range is set to include the median value between the minimum and maximum values ​​of the signal intensity detectable by the acquisition unit 123. In this embodiment, the output unit 80 includes a conversion unit (detection resistor) 83 that converts the current flowing through the first electrode 61 and the second electrode 62 into a voltage, and a reference power supply 86 that outputs a reference voltage Vref. The output unit 80 outputs a signal corresponding to the voltage obtained by subtracting the reference voltage Vref from the voltage converted by the conversion unit 83, and the adjustment unit 123 adjusts the output unit 80 in the above adjustment so that the reference voltage output by the reference power supply 86 is changed. However, the adjustment unit 123 may be configured to adjust the voltage application unit 70 in the above adjustment so that at least one of the voltage value or frequency of the AC voltage applied by the voltage application unit 70 to the first electrode 61 and the second electrode 62 is changed. Furthermore, the output unit 80 may be equipped with a resistor (sensing resistor) 83 for converting the current flowing through the first electrode 61 and the second electrode 62 into a voltage, and the adjustment unit 123 may be configured to adjust the output unit 80 so that the resistance value of the resistor 83 is changed during the adjustment. Also, the adjustment unit 123 can perform the above adjustment when the power of the image forming apparatus 100 is turned ON, before image forming is started. The image forming apparatus 100 may also have an openable and closable door 43 that allows access to the inside of the image forming apparatus 100, and a sensor (open / close sensor) 110 that detects the opening and closing of the door 43, and the adjustment unit 123 can perform the above adjustment based on the detection by the sensor 110 that the door 43 has been opened. Also, the adjustment unit 123 can perform the above adjustment during the preparatory operation (pre-rotation operation) immediately before starting image forming.

[0070] As explained above, this embodiment makes it possible to suppress the decrease in toner level detection accuracy or the inability to detect toner level due to changes in parameters related to the output voltage Vsns. Therefore, in a configuration that acquires information on toner level using a capacitive method, this embodiment makes it possible to maintain the accuracy of the acquired information on toner level regardless of variations in components or changes in the environment.

[0071] [Example 2] <Setting the abnormal detection threshold voltage> Next, other embodiments of the present invention will be described. The basic configuration and operation of the image forming apparatus in this embodiment are the same as those of the image forming apparatus in Embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus in Embodiment 1 are denoted by the same reference numerals as in Embodiment 1, and detailed descriptions are omitted.

[0072] Figure 9 is a schematic diagram showing an example of the waveform of the output voltage Vsns of the capacitance detection unit 80 when Vsns_AD is adjusted to AD2 by the output voltage Vsns adjustment control described in Example 1, and then toner level detection control is started.

[0073] In this embodiment, the CPU 124 determines AD2 by adjusting the output voltage Vsns, and then calculates an abnormality detection threshold voltage based on the value of AD2. For example, AD2+α and AD2-α are calculated as abnormality detection threshold voltages. AD2+α is also called "F / S_Vth_Hi," and AD2-α is also called "F / S_Vth_Lo." The calculated abnormality detection threshold voltage is reflected when the output voltage Vsns adjustment control is completed and the toner level detection control is started. Then, abnormality detection is enabled with an abnormality detection range of voltages higher than F / S_Vth_Hi and voltages lower than F / S_Vth_Lo. If the value of Vsns_AD is higher than the abnormality detection threshold voltage F / S_Vth_Hi or lower than F / S_Vth_Lo, the CPU 124 can take the following actions, for example. In other words, the CPU 124 can control the system to disable the toner level detection control. Furthermore, the CPU 124 can disable the toner level detection control and, after a certain period of time has elapsed, restart control from the output voltage Vsns adjustment control. Disabling the toner level detection control may involve not applying voltage to the first electrode 61 and the second electrode 62, not performing calculations to determine the toner level, not providing notifications of the toner level, or providing a notification that the toner level detection is abnormal. The CPU 124 may perform at least one of these actions as a way of disabling the toner level detection control. In this way, the CPU 124 can execute processing to suppress false detection of the toner level, for example, when Vsns_AD fluctuates due to a short circuit in the signal line of the output voltage Vsns or disturbance noise.

[0074] The value of α is set to a value higher than the voltage difference (ΔV) between Vsns_AD when there is no toner T in the toner detection unit 65 and Vsns_AD when there is toner T in the toner detection unit 65. Vsns_AD when there is no toner T in the toner detection unit 65 can be called the maximum value Vmax of the adjusted Vsns_AD. Also, Vsns_AD when there is toner T in the toner detection unit 65 can be called the minimum value Vmin of the adjusted Vsns_AD. In this embodiment, AD2, which is Vsns_AD adjusted by the output voltage Vsns adjustment control, is acquired before the stirring member 63 stirs. Therefore, it is unknown whether the adjustment was made when there was no toner T in the toner detection unit 65 or when there was toner T in the toner detection unit 65. During the execution of toner remaining amount detection control, the toner T is stirred by the stirring member 63, and as shown in Figure 9, an amplitude of ΔV is generated in Vsns_AD relative to the adjusted AD2. Therefore, by setting a normal range wider than AD2-ΔV to AD2+ΔV, false abnormality detection can be suppressed, and toner level detection control can be performed correctly. Note that the method of setting α in this embodiment is just one example, and a different value from ΔV may be set.

[0075] Figures 10(a) and (b) illustrate the difference in abnormality detection between cases where output voltage Vsns adjustment control is performed (this embodiment) and cases where it is not performed (comparative example). Both Figures 10(a) and (b) are graphs showing the relationship between the capacitance of the capacitance unit 64 and Vsns_AD, with the vertical axis representing Vsns_AD and the horizontal axis representing the capacitance of the capacitance unit 64. Vsns_AD is assumed to have variations in characteristics between min (minimum value characteristic) and max (maximum value characteristic) as shown in Figures 10(a) and (b), due to variations in the parameters that determine the output voltage Vsns. Figures 10(a) and (b) both show cases where it is desirable to define the abnormality detection range as when the capacitance of the capacitance unit 64 is outside the range of 2.5pF to 5.5pF. Figure 10(a) shows the above relationship when output voltage Vsns adjustment control is not performed (comparative example). Figure 10(b) shows the above relationship when output voltage Vsns adjustment control is performed (this embodiment).

[0076] As shown in Figure 10(a), if output voltage Vsns adjustment control is not performed, the abnormality detection range is set as follows, taking into account the variation in the parameters that determine the output voltage Vsns. Specifically, the abnormality detection range is defined as 3V or higher, which is the maximum value of Vsns_AD when the capacitance of the capacitance unit 64 is 2.5pF, and 0.3V or lower, which is the minimum value of Vsns_AD when the capacitance of the capacitance unit 64 is 5.5pF. For example, if the characteristic of Vsns_AD is a typ characteristic between the min characteristic and the max characteristic, the value of Vsns_AD when the capacitance of the capacitance unit 64 is 4pF is 1.65V. Therefore, in this case, an abnormality is detected if a voltage fluctuation occurs that causes Vsns_AD to become 1.35V or higher or 1.35V or lower. Also, in the case of the typ characteristic, the value of Vsns_AD when the capacitance of the capacitance unit 64 is 5pF is 1.05V. Therefore, in this case, an abnormality is detected if a voltage fluctuation occurs that causes Vsns_AD to rise by 1.85V or more, or to fall by 0.75V or more. Thus, if output voltage Vsns adjustment control is not performed, the amount of voltage fluctuation in Vsns_AD that leads to abnormality detection will differ depending on the capacitance of the capacitance unit 64 and the variation in the parameters that determine the output voltage Vsns. To give a specific example, the following may occur. In other words, in the case of the typ characteristic, when the capacitance of the capacitance unit 64 is 4pF, an abnormality is detected with a voltage fluctuation that causes Vsns_AD to rise by 1.35V. However, in the case of the typ characteristic, when the capacitance unit 64 is 5pF, an abnormality is not detected with the same voltage fluctuation that causes Vsns_AD to rise by 1.35V as described above.

[0077] As shown in Figure 10(b), when output voltage Vsns adjustment control is performed, the value of Vsns_AD is adjusted to AD2 regardless of the variation in the capacitance of the capacitance unit 64 or the parameters that determine the output voltage Vsns. Therefore, it is not necessary to set the abnormality detection range considering the variation in the capacitance of the capacitance unit 64 or the parameters that determine the output voltage Vsns. For example, if AD2 is 1.65V and α is 0.5V, an abnormality is detected if a voltage fluctuation occurs that causes Vsns_AD to become 0.5V higher or lower than 0.5V, regardless of the variation in the parameters that determine the output voltage Vsns. Thus, when output voltage Vsns adjustment control is performed, the amount of voltage fluctuation in Vsns_AD that leads to abnormality detection does not change due to the variation in the capacitance of the capacitance unit 64 or the parameters that determine the output voltage Vsns. Furthermore, it is possible to change the abnormality detection range by changing the setting value of α. Therefore, an abnormality detection range can be set to match the design philosophy, etc., so that normal and abnormal conditions can be distinguished with sufficient accuracy. This allows for accurate anomaly detection regardless of variations in the capacitance of the capacitance unit 64 or the parameters that determine the output voltage Vsns.

[0078] In this way, by performing output voltage Vsns adjustment control, it is possible to appropriately set an abnormality detection range that can detect abnormalities regardless of the capacitance of the capacitance unit 64 or the parameters that determine the output voltage Vsns. Therefore, compared to not performing output voltage Vsns adjustment control, it is possible to distinguish between normal and abnormal conditions more accurately when output voltage Vsns adjustment control is performed.

[0079] In this way, the control unit 124 can set an abnormal range for the intensity of the first signal (a signal output by the output unit 80 when stirring is being performed) for detecting abnormalities in the acquired value (toner level), based on the intensity of the second signal (a signal output by the output unit 80 when stirring is not being performed) which is within a predetermined range through adjustment by the adjustment unit 123. When the control unit 124 detects that the intensity of the first signal is within the abnormal range, it can control the notification unit (display unit) 50 to disable the notification of the acquired value. At this time, the control unit 124 can set the abnormal range to an intensity of the first signal that is greater than the intensity of the second signal within the predetermined range plus a predetermined value through the above adjustment. Alternatively, the control unit 124 can set the abnormal range to an intensity of the first signal that is less than the intensity of the second signal within the predetermined range minus a predetermined value through the above adjustment.

[0080] As explained above, this embodiment improves the accuracy of anomaly detection and suppresses situations where toner levels are incorrectly detected or cannot be detected at all. [Explanation of Symbols]

[0081] 15 Cartridge Unit 60 Toner storage compartment 61 1st electrode 62 2nd electrode 65 Toner detection unit 70 AC voltage output section 80 Capacitance detection unit 100 Image forming apparatus 101 Main unit of the device 123 Engine Controller 124 CPU

Claims

1. A developing device, A roller that holds the toner, A storage section for storing toner to be carried on the roller, In the aforementioned housing section, the first electrode and the second electrode are opposite to each other, A stirring member for stirring the toner in the storage section, the stirring member rotating so as toner is supplied between the first electrode and the second electrode, A developing apparatus having, The main body of the apparatus, which is equipped with the aforementioned developing device, A voltage application unit that applies an AC voltage to the first electrode and the second electrode, An output unit that outputs a signal corresponding to the capacitance between the first electrode and the second electrode, An adjustment unit that adjusts at least one of the output unit and the voltage application unit, An acquisition unit that acquires values ​​based on the aforementioned signal, A notification unit that notifies information regarding the remaining toner amount in the storage unit according to the acquired value, A control unit that controls the voltage application unit, output unit, adjustment unit and acquisition unit, A device body having, Equipped with, When the stirring operation by the stirring member is being performed, the signal output by the output unit is designated as the first signal, the acquired value based on the first signal is designated as the first acquired value, and the signal output by the output unit when the stirring operation is not being performed is designated as the second signal, The adjustment unit adjusts at least one of the output unit and the voltage application unit so that the intensity of the second signal falls within a predetermined range. The notification unit provides notification according to the first acquired value based on the first signal output by the output unit, which is in a state where the adjustment has been performed and the second signal falls within the predetermined range. An image forming apparatus characterized by the following:

2. The image forming apparatus according to claim 1, characterized in that the first acquired value is a value based on the duty cycle of the first signal.

3. The image forming apparatus according to claim 1, characterized in that the developing device is detachable from the main body of the apparatus.

4. The image forming apparatus according to claim 1, characterized in that the storage section is provided with a supply port for supplying toner.

5. The image forming apparatus according to any one of claims 1 to 4, characterized in that the predetermined range is set to a range that includes the median value between the minimum and maximum values ​​of the signal intensity detectable by the acquisition unit.

6. The output unit comprises a conversion unit that converts the current flowing through the first electrode and the second electrode into a voltage, and a reference power supply that outputs a reference voltage, and outputs a signal corresponding to the voltage obtained by subtracting the reference voltage from the voltage converted by the conversion unit. The image forming apparatus according to any one of claims 1 to 4, characterized in that the adjustment unit adjusts the output unit so that the reference voltage output by the reference power supply is changed during the adjustment.

7. The image forming apparatus according to any one of claims 1 to 4, characterized in that the adjustment unit adjusts the voltage application unit so that at least one of the voltage value or frequency of the AC voltage is changed during the adjustment.

8. The output unit includes resistors for converting the current flowing through the first electrode and the second electrode into a voltage. The image forming apparatus according to any one of claims 1 to 4, characterized in that the adjustment unit adjusts the output unit so that the resistance value of the resistor is changed during the adjustment.

9. The image forming apparatus according to any one of claims 1 to 4, characterized in that the adjustment unit performs the adjustment when the power of the image forming apparatus is turned ON, before image forming is started.

10. A door that can be opened and closed to allow access to the inside of the image forming apparatus, A sensor for detecting the opening and closing of the aforementioned door, It has, The image forming apparatus according to any one of claims 1 to 4, characterized in that the adjustment unit performs the adjustment based on the detection by the sensor that the door has been opened.

11. The image forming apparatus according to any one of claims 1 to 4, characterized in that the adjustment unit performs the adjustment in a preparatory operation immediately before starting image formation.

12. The image forming apparatus according to any one of claims 1 to 4, characterized in that the control unit sets an abnormal range of the intensity of the first signal for detecting an abnormality in the acquired value based on the intensity of the second signal which is within the predetermined range by the adjustment.

13. The image forming apparatus according to claim 12, characterized in that the control unit controls the notification by the notification unit to disable the notification when it detects the first signal with an intensity within the abnormal range.

14. The image forming apparatus according to claim 12, characterized in that the control unit sets the intensity of the first signal to the abnormal range if it is greater than the intensity of the second signal which is within the predetermined range plus a predetermined value by the adjustment.

15. The image forming apparatus according to claim 12, characterized in that the control unit sets the intensity of the first signal to the abnormal range if it is less than the intensity obtained by subtracting a predetermined value from the intensity of the second signal which is within the predetermined range by the adjustment.

Images