JP2015102713A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of improving the detection accuracy of the residual amount of a developer.SOLUTION: The image forming apparatus forming an image on a recording medium by the developer includes a developing container including a storage part 26 in which the developer is stored and a stirring member 24 rotated to stir the developer stored in the storage part 26, signal output means for detecting a force generated according to the relative movement of the stirring member 24 and the developer and outputting an electrical signal for indicating the level of the force, and developer residual amount detection means for detecting the residual amount of the developer stored in the storage part 26, based on the maximum value of the electrical signal outputted by the signal output means, while the stirring member 24 is continuously rotated a plurality of times.

Description

  The present invention relates to an image forming apparatus.

In an electrophotographic image forming apparatus such as a printer or a copying machine that develops an electrostatic latent image with toner (developer) to form an image on a recording medium, there are various methods for detecting the remaining amount of toner in a toner container. A method has been proposed.
Patent Document 1 proposes a method of detecting the remaining amount of toner by detecting the torque of the rotating shaft of the stirring member in a developing device having a stirring member that stirs the toner in the toner chamber and transports the toner to the developing chamber. Yes. In this remaining amount detection method, the remaining amount is detected by a method using a simple principle and mechanism in which the torque is high when the toner remaining amount is large and the torque is low when the toner amount is small.
Japanese Patent Application Laid-Open No. H10-228667 proposes a stirring member in a toner chamber provided with a piezoelectric material. This remaining amount detection method is a method for detecting the remaining amount of toner in the toner chamber by detecting the voltage generated by the pressure that the piezoelectric material provided on the stirring member receives when the toner is stirred. Since the piezoelectric material can be easily attached to the stirring member, the remaining amount can be easily detected in a small size.

Japanese Patent Laid-Open No. 2004-46011 JP-A-3-271785

  However, any of the conventional remaining amount detection methods is a method in which the toner in the toner chamber is regarded as a resistance component in the rotation direction of the stirring member, and the difficulty around the stirring member is calculated as the remaining amount of toner. When there is a sufficient amount of toner in the toner chamber, even if the toner is continuously stirred, a sufficient amount of toner is stirred as a resistance component by the stirring member, so that a stable output can be obtained and a highly reliable residual can be obtained. A quantity detection result can be obtained. However, when the amount of toner in the toner chamber decreases, the toner scatters and diffuses into the toner chamber when continuously stirred. Therefore, the ratio of the toner scattered in the toner chamber may be relatively large with respect to the ratio of the toner stirred by the stirring member. In such a state, during continuous stirring, the toner does not become a stable resistance component for the stirring member, and the remaining amount of toner may be detected at a low level, or an unstable detection result may be obtained. .

  An object of the present invention is to provide an image forming apparatus capable of improving the detection accuracy of the remaining amount of developer.

In order to achieve the above object, an image forming apparatus of the present invention includes:
An image forming apparatus for forming an image on a recording medium with a developer,
A developing container comprising: a housing portion in which the developer is housed; and a stirring member that stirs the developer housed in the housing portion by rotating;
A signal output means for detecting a force generated with relative movement between the stirring member and the developer and outputting an electric signal indicating the magnitude of the force;
A developer remaining amount detection that detects the remaining amount of developer stored in the storage unit based on the maximum value of the electrical signal output by the signal output means while the stirring member rotates continuously a plurality of times. Means,
It is characterized by providing.
In order to achieve the above object, the image forming apparatus of the present invention includes:
An image forming apparatus for forming an image on a recording medium with a developer,
A developing container comprising: a housing portion in which the developer is housed; and a stirring member that stirs the developer housed in the housing portion by rotating;
A signal output means for detecting a force generated with relative movement between the stirring member and the developer and outputting an electric signal indicating the magnitude of the force;
A developer remaining amount detecting means for detecting the remaining amount of developer accommodated in the accommodating portion based on the maximum value of the electric signal output by the signal output means while the stirring member rotates and makes one round. And.

  According to the present invention, it is possible to improve the detection accuracy of the remaining amount of developer.

1 is a schematic sectional view of a developing device according to Embodiment 1 of the present invention. 1 is a schematic sectional view of an image forming apparatus according to an embodiment of the present invention. The current value of the agitation drive motor of the developing device in Example 1 of the present invention The schematic diagram which shows the mode of rotation of the stirring member in the Example of this invention. FIG. 3 is a block diagram of toner remaining amount detecting means in Embodiment 1 of the present invention. Flowchart of toner remaining amount detection in Embodiment 1 of the present invention The figure which shows the result of the comparison experiment of the residual amount detection result of the Example of this invention, and a prior art example The schematic diagram explaining the structure of the stirring member in the Example of this invention. Generated voltage value of piezo film in Example 2 of the present invention Flowchart of toner remaining amount detection in Embodiment 2 of the present invention

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. That is, it is not intended to limit the scope of the present invention to the following embodiments.

  Here, the image forming apparatus (electrophotographic image forming apparatus) forms an image on a recording material (recording medium) with a developer (toner) using an electrophotographic image forming process. For example, an electrophotographic copying machine, an electrophotographic printer (LED printer, laser beam printer, etc.), an electrophotographic facsimile apparatus, an electrophotographic word processor, and a multifunction machine (multifunction printer) thereof are included. The recording material is a material on which an image is formed, and is a recording medium such as a recording sheet or an OHP sheet.

  The process cartridge is a cartridge in which at least one of an electrophotographic photosensitive drum and at least one of a charging device, a developing unit, and a cleaning unit as a process unit that acts on the electrophotographic photosensitive drum is integrated into a cartridge. The process cartridge is configured to be detachable from the main body of the image forming apparatus. In the following description, an image forming apparatus main body (hereinafter, referred to as “apparatus main body”) is an apparatus constituent portion excluding at least a process cartridge, a developing device or a developing container from the configuration of the apparatus main body.

Example 1
<Image forming apparatus>
FIG. 2 is a schematic cross-sectional view showing a schematic configuration of an image forming apparatus (color laser beam printer) 1 according to an embodiment of the present invention. In the image forming apparatus 1 according to this embodiment, four photosensitive drums 10 (10a to 10d) for carrying latent images of four colors of yellow, magenta, cyan, and black are arranged. Around each photosensitive drum 10, a charging roller 11 (11a to 11d) as a charging unit for uniformly charging the photosensitive drum 10, and a laser beam is irradiated on the photosensitive drum 10 to form a latent image. An exposure device 13 (13a to 13d) is arranged for this purpose. Further, a developing device 20 (20a to 20d) for developing the latent image formed on the photosensitive drum 10 with toner of corresponding colors (yellow, magenta, cyan, black) to be visualized is disposed.

  The intermediate transfer belt 31 is stretched between a support roller 33 and a counter roller 32, and includes four primary transfer rollers 30 (30a to 30d). Each photosensitive drum 10 is in contact with the primary transfer roller 30 via the intermediate transfer belt 31 to form four pairs of primary transfer nips. The secondary transfer roller 40 forms a secondary transfer nip with the counter roller 32 via the intermediate transfer belt 31. An intermediate transfer belt cleaner 34 is disposed at the position of the tension roller 33 of the intermediate transfer belt 31.

  Next, an image forming operation of the image forming apparatus according to the present embodiment will be described. First, yellow image formation will be described. The photosensitive drum 10 a is rotated in the arrow direction (clockwise) in FIG. 2 in synchronization with the rotation of the intermediate transfer belt 31. Then, the surface of the photosensitive drum 10a is uniformly charged by the charging roller 11a, and light is irradiated by the exposure device 13a based on the image data to form a yellow electrostatic latent image on the photosensitive drum 10a.

  At the developing position, a bias having the same polarity as the toner is applied to the developing roller 21a with respect to the negatively charged toner in the developing device 20a. The potential difference causes an electric field in the direction from the developing roller 21a to the photosensitive drum 10a due to the potential difference, and yellow toner is attached to the electrostatic latent image on the photosensitive drum 10a for development. Thereafter, the yellow toner image on the photosensitive drum 10 a is primarily transferred onto the intermediate transfer belt 31.

  For each color of magenta, cyan, and black, electrostatic latent image formation, development, and primary transfer are sequentially performed as in the case of yellow, and four color toner images are superimposed on the intermediate transfer belt 31. To form a full color image.

  On the other hand, the sheet S as a recording material is separated and fed one by one by the sheet feeding roller 60 and fed to the registration roller pair 61. The registration roller pair 61 sends the fed sheet S to the secondary transfer nip formed by the secondary transfer roller 40 and the opposing roller 32 via the intermediate transfer belt 31. In the secondary transfer nip, the full color image on the intermediate transfer belt 31 is secondarily transferred collectively onto the surface of the conveyed sheet S.

  The sheet S on which the toner image is transferred is sent to the fixing device 50. In the fixing device 50, the sheet S is heated and the toner image is fixed on the sheet S. As a result, an image is formed on the sheet S, and the sheet S is discharged from the fixing device 50 to a discharge portion of the upper cover 62 outside the apparatus.

  On the other hand, the secondary transfer residual toner remaining on the intermediate transfer belt 31 without being completely transferred to the sheet S at the secondary transfer nip is removed from the intermediate transfer belt 31 by the intermediate transfer belt cleaner 34. Thus, a series of image forming operations in image formation is completed.

<Developing device>
FIG. 1 is a schematic cross-sectional view showing a schematic configuration of the developing device 20 in the present embodiment. The developing device 20 includes a developing container including a developing chamber 25 and a toner chamber 26, a developing roller 21, a supply roller 22, and a regulating blade 23. The toner chamber 26 serving as a container is provided with a stirring member 24 for stirring and transporting the toner in the toner chamber 26. The supply roller 22 has a configuration in which a sponge-like foam is formed on the outer periphery of the core metal so that the toner can be easily held and conveyed. The developing roller 21 and the supply roller 22 are arranged such that the distance between the rotation shafts is a distance where a part of each diameter overlaps, and the sponge-like surface layer portion of the supply roller 22 is slightly crushed by the surface of the developing roller 21. In contact with each other. The supply roller 22 has a relationship in which the surface of the developing roller 21 and the surface of the supply roller 22 are relatively moved in the opposite directions with respect to the developing roller 21 in a counter direction, that is, in a contact portion (nip portion) with the developing roller 21. Rotate in the direction. The toner taken into the sponge-like surface layer of the supply roller 22 is supplied onto the development roller 21 by the rubbing between the supply roller 22 and the development roller 21 in the nip portion due to this rotation.

  In the developing roller 21, the thickness of the toner layer supplied from the supply roller 22 is controlled by a regulating blade 23 that abuts a tip portion extending in the counter direction with respect to the rotation direction of the developing roller 21. Further, the developing roller 21 is given a desired charge at a contact portion (regulation nip) with the regulation blade 23. The charged toner on the developing roller 21 is used for developing the electrostatic latent image formed on the photosensitive drum 10 at the developing nip where the developing roller 21 and the photosensitive drum 10 abut.

  The toner filled in the toner chamber 26 is pumped up to the developing chamber 25 by the stirring member 24. The agitating member 24 has a configuration in which a flexible sheet 241 is attached to a rotation support member. The agitation member 24 agitates the toner in the toner chamber 26 with the agitating sheet 241 having flexibility, and the flexible recoil. The toner is pumped up to the developing chamber 25 by using. The pumped toner is stored in the vicinity of the supply roller 22.

<Toner residual detection>
With reference to FIGS. 3 and 4, the toner remaining amount detection in this embodiment will be described. In this embodiment, the toner remaining amount is detected by detecting the torque generated in the stirring drive motor that rotationally drives the stirring member 24. The stirring drive motor operates using power supplied from a power source as a power source. The torque of the stirring drive motor is measured by monitoring the drive current value or drive voltage value flowing through the motor. In this embodiment, a case where a motor drive current value is used will be described. FIG. 3 shows the current value detected from the stirring drive motor while the stirring member 24 rotates three times from the stop state. FIG. 4 is a schematic diagram showing how the stirring member 24 rotates. The stirring member 24 rotates once in the order of (a) → (b) → (c) → (d).

  When the stirring is stopped, the stirring member 24 is stopped at a phase not contacting the toner agent surface (the upper surface of the toner accumulated in the toner chamber 26) (FIG. 4A). Then, with the start of stirring, the current value of the stirring drive motor rises to some extent (state before a1 in FIG. 3).

  3 indicates a range of current values detected until the stirring member 24 that has started rotating contacts the upper surface of the accumulated toner. That is, the current value detected at a1 is a value detected when the stirring member 24 rotates without contacting the toner, and is a current value necessary to rotate the stirring member 24.

3, when the stirring member 24 comes into contact with the upper surface of the accumulated toner (FIG. 4B), and all the toner accumulated in the bottom of the toner chamber 26 is agitated through the toner accumulation region ( FIG. 4C shows the range of current values detected. The current value detected in this range increases by the amount of accumulated toner. Further, when the stirring member 24 enters the accumulated toner,
The stirring sheet 241 having flexibility is bent by the pressure received from the toner. Then, the force to restore the stirring sheet 241 is applied to the stirring drive motor reactively, and the current value of the stirring drive motor jumps up instantaneously according to the amount of toner.

  C1 in FIG. 3 indicates a range of current values detected when the stirring member 24 jumps the toner upward toward the developing chamber 25 (FIG. 4D) and escapes from the toner accumulation region. Yes. At this time, since the stirring member 24 is in a state where there is no toner load, the current value is substantially the same as a1. The above is the current value detected in the first round of stirring.

  In the second round of stirring, since a part of the accumulated toner is splashed up toward the developing chamber 25 by the first round of stirring, the toner accumulation state in b2 where the stirring member 24 again touches the upper surface of the deposited toner. Is often different from the first round of stirring. In particular, in a state where the remaining amount of toner in the toner chamber 26 is not small, the ratio of the toner scattered in the toner chamber 26 by the stirring member 24 after the second round of stirring increases, and the ratio of the accumulated toner, that is, the stirring member 24. The ratio of the toner that exhibits resistance to the toner becomes small. Therefore, the state in the toner chamber 26 is close to an empty state of the toner, and the current values at b2 and b3 are lower than the current value at b1.

  As described above, when the agitating member 24 first comes into contact with the toner agent surface from the state where the toner in the toner chamber 26 is stable with a certain remaining amount of toner, the toner in the toner chamber 26 has the largest amount of toner. Stirring is performed, and an elastic restoring force of the stirring sheet 241 is applied. Therefore, at this time, the value of the current flowing through the stirring drive motor of the stirring member 24 becomes the largest. By using this maximum value as the output value for the remaining amount detection, the difference from the state in which there is no toner in the toner chamber 26 can be increased, and the remaining amount detection accuracy can be increased.

  For the above reasons, the current value of the agitation drive motor is monitored by the current measurement circuit when the agitation member 24 continuously rotates a plurality of times without stopping for at least two rotations from the start of driving, and the maximum The value is used as an output value for toner remaining amount detection. As a result, even when the remaining amount of toner in the toner chamber 26 is small, the output value can be relatively large compared to when the remaining amount of toner is zero, and the accuracy of remaining amount detection can be improved. Note that, as described above, when the remaining amount of toner is not small, the current value detected in the first round of a plurality of times tends to become the maximum value, so that it is detected in the first round according to the remaining amount of toner. The remaining amount may be detected using only the maximum current value.

  Further, in this embodiment, control is performed so that the stop phase of the stirring member 24 is always in the same place. By making the stirring member 24 stand still at a phase (FIG. 4A) that does not contact the toner in the toner chamber 26, a larger amount of toner can be stirred at the time of stirring, and the accuracy of remaining amount detection can be improved. it can. Such a phase control of the agitating member 24 is conventionally well-known such as a method of specifying the phase from the waveform of the current value of the driving torque of the agitating member 24, or optically detecting the phase of the gear that drives the agitating member 24. This method can be realized.

With reference to FIG. 5 and FIG. 6, control of toner remaining amount detection will be described. FIG. 5 is a block diagram illustrating a control configuration for toner remaining amount detection. FIG. 6 is a flowchart of toner remaining amount detection. Various operations of the image forming apparatus are controlled by a CPU as a control unit. The image forming apparatus is provided with an internal storage device composed of ROM, RAM, or the like as storage means, and the CPU performs various controls using information necessary for various calculations stored in the internal storage device. Do. In the present embodiment, a motor driving current value that is a current detection unit is used as a signal output unit that detects a force generated with the relative movement of the stirring member 24 and the toner and outputs an electric signal indicating the magnitude of the force. A measurement circuit is provided. The CPU, as the developer remaining amount detecting means, is based on the current value output from the motor drive current value measurement circuit while the stirring member continuously rotates a plurality of times.
The remaining amount of toner stored in the toner chamber 26 as a storage unit is detected. When a print signal is input to the image forming apparatus from an information device such as a PC (S101), an image forming operation is started (S102). Then, the stirring drive motor of the stirring member 24 that supplies toner from the toner chamber 26 to the developing chamber 25 also starts to be driven (S103). The current value of the agitation drive motor is measured by the motor drive current value measurement circuit from the start of agitation drive until the agitation member 24 makes one round (S104). Then, the maximum value among the measured current values is determined by the CPU and output as an output value (S105). The CPU compares the output value with the output value / toner remaining amount conversion table stored in the internal storage device (S106), thereby determining the toner remaining amount in the toner chamber (S107). When the remaining amount of toner has not reached 0% (No in S108), the remaining amount of toner is notified to the user at an arbitrary timing by a notification unit such as a display provided in the image forming apparatus by the remaining toner amount notification circuit ( In S109, the image formation is completed (S110). When the remaining amount of toner reaches 0% (S108, Yes), image formation is forcibly terminated (S111), and the user is informed that the toner has run out (S112).

<Comparison experiment>
An experiment was performed in comparison with the comparative example as to whether or not the toner remaining amount detecting method in the present embodiment can be accurately detected even when the toner remaining amount in the toner chamber is small. In the toner remaining amount detection of this embodiment, the stirring drive motor current value of the stirring member 24 during the image forming operation is measured, and the maximum value of the current value is adopted as the output value of the toner remaining amount detection. On the other hand, the remaining amount detection method of the conventional example as a comparative example is a method of performing an averaging process generally performed to stabilize the output value. In this method, the drive motor current value of the agitating member during the image forming operation is measured, and a value obtained by averaging the measured values is used as an output value of the remaining toner amount detection.

  FIG. 7 is a plot of toner remaining amount detection output values from 100% to 0% in units of 10% of the remaining amount of toner in the toner chamber in this experiment. Further, the output value of 100% toner remaining amount in each remaining amount detection method is set to 100%, and the output value of each remaining toner amount 0% is displayed as 0%. As shown in the figure, in this embodiment, the detection result that the remaining amount of toner and the output value are in a substantially proportional state is obtained, and the output value can be obtained at a certain high value even when the remaining amount of toner is low. Therefore, the remaining amount of toner with high detection accuracy can be notified to the user without being affected by variations and some noises. On the other hand, in the conventional example, as the remaining amount of toner decreases, the output value decreases, and the difference from 0% is very small. This output characteristic is likely to be affected by noise or the like when the remaining amount of toner is low, and there is a possibility that the user may be notified of an incorrect remaining amount of toner. As described above, by setting the maximum value of the drive motor current value of the agitating member 24 as the output value of the remaining amount detection, the remaining amount of toner can be detected with high accuracy even when the amount of toner in the toner chamber is small.

(Example 2)
With reference to FIGS. 8 to 10, an image forming apparatus according to Embodiment 2 of the present invention will be described. Here, differences from the first embodiment will be mainly described, and the same reference numerals are given to configurations common to the first embodiment, and detailed description thereof will be omitted. Matters not specifically mentioned here are the same as those in the first embodiment.

  In Example 1, the current value of the agitation drive motor during image formation is monitored, and the remaining amount of toner with high detection accuracy is realized by using the maximum value as an output value during continuous rotation a plurality of times. . In this detection method, in order to increase detection accuracy, the maximum value of the current value monitored during stirring is used as an output value. In principle, the largest output value can be obtained in the first rotation of the stirring member. That is, the remaining amount of toner at the start of one job is detected.

By the way, an image forming apparatus having a higher printing speed tends to increase the number of recording materials output in one job. Therefore, in particular, when a large amount of an image pattern with a high printing rate is output in one job, a large amount of toner is consumed in one job, and it is considered that the toner runs out during one job. In such a situation, when only the remaining amount of toner at the start of one job is detected and notified to the user, there is a possibility that the image forming operation may be continued without noticing out of toner during the job. Therefore, in the second embodiment, even when a long job (for example, a job with a large amount of toner consumption in one output and a large number of outputs in one job) is executed, the remaining amount of toner is appropriately detected and the user is informed of the toner. An example of notifying the remaining amount will be described.

  Here, before describing the control of the second embodiment, a configuration for detecting the remaining amount of toner suitable for an image forming apparatus having a high printing speed and a long life will be described. In an image forming apparatus having a high printing speed and a long service life, the torque increases due to wear and deterioration of the main body side gear train (not shown) that transmits driving to the stirring member 24 due to durability, and the current value of the stirring drive motor May become large. Therefore, in the configuration of the toner remaining amount detection using the current value of the stirring drive motor of the configuration of the first embodiment, the output value is changed due to the influence of the durability on the main body side, leading to a decrease in detection accuracy. Is also possible.

  Therefore, in Example 2, as shown in FIGS. 8B and 8C, the film-like piezoelectric element 243 is provided on the stirring sheet 241 of the stirring member 24, and the toner remaining amount is changed by the change in the toner powder pressure applied to the piezoelectric element 243. Perform volume detection. FIG. 8B is a schematic sectional view of the stirring member 24, and FIG. 8C is a schematic front view of the stirring member 22. The polymer piezoelectric element is provided in such a manner that the piezoelectric surface in the thickness direction of the piezoelectric element and the stirring blade surface of the stirring sheet 241 coincide with each other. However, in this embodiment, the agitating sheet is such that the rolling direction during the production of the high-piezoelectricity of the polymer piezoelectric element 243 (hereinafter referred to as a piezo film) formed in a sheet shape is orthogonal to the agitation rotating shaft 242. It was made to adhere to the stirring blade surface of 241.

  The piezo film 243 can be thinned and has the characteristics of having flexibility. Since the film is thin and the cross-sectional area is very small, a large stress in the material is generated from a force in a small rolling direction. This feature makes the sensitivity much higher in the rolling direction than in the thickness direction, and the standard effective sensitivity in the rolling direction vs. the thickness direction is about 1000: 1. When this piezo film 243 is adhered to the stirring sheet 241, the stirring sheet 241 bends according to the toner powder pressure during stirring, so that the piezo film 243 is also bent. When the piezo film 243 is bent, elongation occurs in the rolling direction, so that a voltage corresponding to the amount of bending is generated. Therefore, since the piezo film 243 generates a voltage corresponding to the remaining amount of toner when the toner is stirred, the remaining amount of toner can be detected by detecting this voltage with the generated voltage detection circuit 244. With such a configuration, even in a high-speed and long-life image forming apparatus, it is possible to detect the remaining amount of toner with high accuracy that is not easily affected by the outside of the developing unit such as a gear train of the image forming apparatus main body.

The configuration of the piezo film 243 will be described in more detail with reference to FIG. FIG. 8A is a schematic cross-sectional view of the piezo film 243 in this example. In this example, a piezo film manufactured by Tokyo Sensor Co., Ltd. was used as the piezo film 243. The material is polyvinylidene fluoride (PVDF) and the thickness is 20 μm. Silver ink electrodes 243b are respectively formed on both the front and back surfaces of the piezopolymer substrate 243a, and are adhered to an insulating stirring sheet 241 so that the rolling direction during manufacture with the highest piezoelectricity is perpendicular to the rotation axis of stirring. In this embodiment, as shown in FIG. 8C, a piezo film 243 having a width of 10 mm is bonded to the stirring sheet 241 so as to be integrated with the longitudinal central portion of the surface upstream of the stirring sheet 241 in the rotation direction. . The stirring sheet 241 is made of polyphenylene sulfide (PPS) and has a thickness of 150 μm so as to be flexible with respect to bending stress and with sufficient elastic restoring force against bending stress. The electrode surface of the piezo film 243 is guided to the outside by a metal film (not shown) and a metal wire, and is connected to the generated voltage detection circuit 244 of the image forming apparatus main body by a sliding electrode.

  FIG. 9 is a diagram showing a detection profile of a voltage generated between the electrodes 243b of the piezo film 243 while the stirring member 24 rotates three times from the stopped state. 9 indicates the range of voltage values detected until the stirring member 24 that has started rotating contacts the upper surface of the accumulated toner (FIG. 4A). The stirring sheet 241 starts to rotate from the 9 o'clock position in FIG. 1 and does not bend during a1 in FIG. 9, that is, until it contacts the toner agent surface, and thus no voltage is generated.

  FIG. 9B1 shows the case where the stirring member 24 comes into contact with the upper surface of the deposited toner (FIG. 4B) and stirs all the toner that has progressed in the toner accumulation area and accumulated on the bottom of the toner chamber 26 (see FIG. 9). FIG. 4C shows the range of detected voltage values. The tip of the stirring sheet 241 begins to enter the toner agent surface, and at the same time, the amount of bending of the stirring sheet 241 begins to change, and at the same time, the amount of bending of the piezo film 243 due to the bending of the stirring sheet 241 as shown in b1 of FIG. A voltage corresponding to is generated. The amount of deflection of the piezo film 243 passing through the deposition region gradually increases thereafter, and the voltage also increases. The amount of deflection of the stirring sheet 241 is maximized at the moment when the toner is flipped up, and the voltage value output from the piezo film 243 is also maximized.

  In FIG. 9, c <b> 1 indicates a range of voltage values detected when the stirring member 24 jumps the toner upward toward the developing chamber 25 and passes through the toner accumulation region. The stirrer sheet 241 is released from bending after the toner is sprung up. At this time, since the stirring sheet 241 is rapidly deformed in the direction in which the bending returns (FIG. 4D), the piezo film 243 responds to the change in the bending direction and the rapid change in the amount of bending, and has a large reverse direction. Generate voltage. Thereafter, the voltage generated in the piezo film 243 decreases as the amount of deflection of the stirring sheet 241 is eliminated. From the second round onward, since the toner is scattered by stirring, the ratio of the accumulated toner is decreased, and the amount of deflection of the stirring sheet 241 is decreased by the amount of the scattered toner in b2 and b3, The voltage value output from the piezo film 243 also decreases. Therefore, it is possible to detect the remaining amount of toner with high detection accuracy by measuring the voltage value of the piezo film 243 at least two times from the start of the stirring drive. The voltage value used for the remaining amount detection is detected when the stirrer sheet 241 is greatly bent in the reverse direction due to the reaction after the toner is sprung up instead of the maximum value at the moment when the toner is sprung up. May be used.

  With reference to FIG. 10, control of toner remaining amount detection in the second embodiment will be described. FIG. 10 is a flowchart of toner remaining amount detection in the second embodiment. This control is a control capable of appropriately detecting the remaining amount of toner and notifying the user of the remaining amount of toner even when a long job is output in the second embodiment. Note that this control may be applied to the first embodiment.

When a print signal is input to the image forming apparatus from an information device such as a PC (S201), an image forming operation is started (S202), and the stirring member 24 that supplies toner from the toner chamber 26 to the developing chamber 25 is rotated. Start (S203). The voltage value output from the piezo film 243 due to the bending of the stirring sheet 241 of the stirring member 24 is measured by the generated voltage detection circuit 244 from the start of stirring driving until the stirring member 24 makes one round. The maximum value among the measured voltage values is determined by the CPU and output as an output value. The CPU compares the output value with an output value / toner remaining amount conversion table stored in the internal storage device. Thus, the remaining amount of toner in the toner chamber is determined (S204). When the remaining amount of toner has not reached 0% (No in S208), the remaining amount of toner is notified to the user at an arbitrary timing by a notification unit such as a display provided in the image forming apparatus by the remaining toner amount notification circuit ( In S206, the image formation is completed (S207). Then, if the job is finished, this control is finished (S208, Yes). On the other hand, when the remaining amount of toner reaches 0% (S205, Yes), the image formation is forcibly terminated (S214) and the job is also forcibly terminated (S215). It is notified that there is no more (S216).

  If the job has not ended in S208, the following control is performed. When the amount of toner remaining in the toner chamber is small, in order to increase the accuracy of toner remaining amount detection, it is necessary to stop stirring and start stirring while the toner surface is stable. Therefore, when a large number of print signals are input in one job, the interval between sheets is extended in the middle of the job, and the agitation is temporarily stopped to detect the remaining amount of toner in the meantime. Detection is performed and control for restarting image formation is performed.

  Specifically, a number counter for counting the number of image formations in one job is provided, and the number of the number counter is incremented by 1 every time one image is formed (S209), and when 30 is reached (S210, Yes) The paper interval extension control for 3 seconds is performed (S211). The number counter is reset to 0 every time it reaches 30. Until it reaches 30 (No in S210), image formation is performed without performing the inter-paper extension control (S213). Stirring is stopped for 3 seconds between paper extension control (S212). With the stirring stopped for 3 seconds, the toner in the toner chamber is collected at the bottom of the toner chamber. Thereafter, stirring is started again, and the voltage value of the piezo film is monitored for one turn from the start of driving of the stirring member, and the remaining amount of toner is detected. By performing such control, even if a large amount of print signals are input in one job, it is possible to detect the toner out and notify the user.

  In addition, the condition for entering the sheet interval extension control may be changed according to the remaining amount of toner. For example, when there is a sufficient remaining amount of toner, the sheet counter is not used and the inter-paper extension control is not performed. Then, when the remaining amount of toner falls below 30%, the number of times of image formation is counted by the number counter, and when it reaches 30, the inter-paper extension control is performed for 3 seconds. By doing so, it is possible to suppress a decrease in throughput when there is sufficient toner.

  It is also possible to detect the remaining amount of toner after waiting for the toner agent surface to stabilize by temporarily stopping only the stirring member 24 while continuing the image forming operation without performing the inter-paper extension control. In the case of this method, for example, when the remaining amount of toner is small, it is necessary to perform control so that the supply of toner to the developing chamber is not insufficient due to the stirring member being stopped.

  In this embodiment, the condition for performing the sheet interval extension control has been described in the case where the number counter reaches 30. However, the condition may be changed according to the specifications of the image forming apparatus and the developing device.

  In each of the above-described embodiments, the developing device has been described in which toner is assembled upward from the toner chamber 26 below the developing container to the developing chamber 25 in which the developing roller 21 is disposed. The present invention can also be applied to a developing device configured to convey.

  Further, in this embodiment, the piezo film 243 is attached to the stirring sheet 241 at the center in the longitudinal direction and the width in the lateral direction (direction perpendicular to the longitudinal direction), but the present invention is not limited to this. is not. The position, shape, and number of sheets to be attached may be arbitrarily changed according to the stirring configuration and the developing container configuration. Further, although the surface to which the piezo film 243 is attached is the upstream surface in the rotation direction of the stirring sheet 241, it may be attached to the downstream surface.

  The remaining amount detection method in each of the above embodiments may be applied to a configuration in which a piezoelectric element is provided on a rigid plate-like stirring member, for example, which is not a flexible sheet. Also, the piezoelectric element is not limited to a film-like one.

  20 ... developing device, 24 ... stirring member, 26 ... toner chamber

Claims (15)

An image forming apparatus for forming an image on a recording medium with a developer,
A developing container comprising: a housing portion in which the developer is housed; and a stirring member that stirs the developer housed in the housing portion by rotating;
A signal output means for detecting a force generated with relative movement between the stirring member and the developer and outputting an electric signal indicating the magnitude of the force;
A developer remaining amount detection that detects the remaining amount of developer stored in the storage unit based on the maximum value of the electrical signal output by the signal output means while the stirring member rotates continuously a plurality of times. Means,
An image forming apparatus comprising: An image forming apparatus for forming an image on a recording medium with a developer,
A developing container comprising: a housing portion in which the developer is housed; and a stirring member that stirs the developer housed in the housing portion by rotating;
A signal output means for detecting a force generated with relative movement between the stirring member and the developer and outputting an electric signal indicating the magnitude of the force;
A developer remaining amount detecting means for detecting the remaining amount of developer accommodated in the accommodating portion based on the maximum value of the electric signal output by the signal output means while the stirring member rotates and makes one round. And an image forming apparatus.   The developer remaining amount detecting means is accommodated in the accommodating portion based on the maximum value of the electrical signal output by the signal output means in the first round when the stirring member rotates continuously a plurality of times. The image forming apparatus according to claim 2, wherein the remaining amount of the developer is detected. The signal output means includes
A motor for rotating the stirring member;
Current detection means for detecting and outputting a current flowing through the motor;
Including
2. The developer remaining amount detecting unit detects a remaining amount of developer stored in the storage unit based on a maximum value of a current value output from the current detecting unit. 4. The image forming apparatus according to any one of items 3.   The maximum value of the current value output by the current detection unit is a maximum value of a current value detected when the tip of the stirring member enters a developer accumulation region in the storage unit. 5. The image forming apparatus according to 4. The signal output means includes
A piezoelectric element provided on the stirring member and outputting a voltage by deformation;
Voltage detection means for detecting and outputting the voltage output by the piezoelectric element;
The developer remaining amount detecting unit detects a remaining amount of developer stored in the storage unit based on a maximum value of a voltage value output from the voltage detecting unit. 4. The image forming apparatus according to any one of items 3.   The maximum value of the voltage value output by the voltage detection unit is a maximum value of a voltage value detected when the tip of the stirring member passes through a developer accumulation region in the storage unit. 6. The image forming apparatus according to 6. The maximum value of the voltage value output by the voltage detection means is the maximum value of the voltage value detected when the tip of the stirring member is deformed due to a reaction when the tip of the stirring member escapes from the developer accumulation region. The image forming apparatus according to claim 6.   The image forming apparatus according to claim 6, wherein the piezoelectric element is provided on an upstream surface of the stirring member in a rotation direction.   The image forming apparatus according to claim 6, wherein the piezoelectric element has a long shape in a direction orthogonal to a rotation axis of the stirring member.   The image forming apparatus according to claim 6, wherein the piezoelectric element is provided at least in a central portion in a direction of a rotation axis of the stirring member.   The image forming apparatus according to claim 6, wherein the piezoelectric element is a film-like member attached to the stirring member.   The image forming apparatus according to claim 1, wherein the stirring member is a flexible sheet-like member.   The image forming apparatus according to claim 1, wherein the developing container is configured to be detachable from an apparatus main body of the image forming apparatus.   The image forming apparatus according to claim 1, wherein the developing container is provided in a developing device or a process cartridge configured to be detachable from an apparatus main body of the image forming apparatus. apparatus.

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