Image forming apparatus

Abstract

To provide a new type of image forming apparatus. [Solution] The image forming apparatus comprises a first housing section and a second housing section, a rotating rotary, a first permanent magnet supported inside the first housing section, a second permanent magnet supported inside the second housing section, a first sensor, a second sensor, and one or more CPUs. The first time point is defined as the time when one hour has elapsed from the time when the second sensor detects the orientation of the rotary, and the second time point is defined as the time when two hours have elapsed. At the first time point, the shortest distance between the first permanent magnet and the first sensor is shorter than the shortest distance between the second permanent magnet and the first sensor. At the second time point, the shortest distance between the second permanent magnet and the first sensor is shorter than the shortest distance between the first permanent magnet and the first sensor. One or more CPUs determine, based on the signal at the first time point, that the amount of developer in the first housing section is less than a first threshold, and based on the signal at the second time point, that the amount of developer in the second housing section is less than a second threshold.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a configuration for detecting the amount of developer in each developing unit in an image forming apparatus using a plurality of developing units. According to Patent Document 1, a movable magnetic body is provided inside a storage portion that stores developer in each developing unit, and the amount of developer is detected by detecting magnetism emitted by the magnetic body with a reed sensor. Further, according to Patent Document 1, the magnetic body is oscillated by rotationally driving an eccentric cam in order to prevent the magnetic body from being buried in the developer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide an image forming apparatus of a new form.

Means for Solving the Problems

[0005] According to one aspect of the present invention, an image forming apparatus comprises a first storage section for storing a first developer and a second storage section for storing a second developer, a rotating rotary, a first permanent magnet supported in the first storage section so as to be movable within the first storage section, a second permanent magnet supported in the second storage section so as to be movable within the second storage section, a first sensor provided outside the rotary, which detects a magnetic field and outputs a signal, a second sensor for detecting the rotary in a detected position, and one or more CPUs, wherein the time when the second sensor detects the rotary in the detected position is defined as the detection time, and the time when a first time has elapsed from the detection time is defined as the first time The first time point is defined as the point in time two hours after the detection point, and the second time point is defined as the point in time two hours after the detection point. At the first time point, the shortest distance between the first permanent magnet and the first sensor is shorter than the shortest distance between the second permanent magnet and the first sensor. At the second time point, the shortest distance between the second permanent magnet and the first sensor is shorter than the shortest distance between the first permanent magnet and the first sensor. Based on the signal at the first time point, one or more CPUs determine that the amount of the first developer in the first housing is less than a first threshold. Based on the signal at the second time point, one or more CPUs determine that the amount of the second developer in the second housing is less than a second threshold. [Effects of the Invention]

[0006] According to the present invention, a new form of image forming apparatus can be provided. [Brief explanation of the drawing]

[0007] [Figure 1] Cross-sectional view of an image forming apparatus. [Figure 2] Diagram illustrating the developing unit and cartridge. [Figure 3] A perspective view of a rotary tiller. [Figure 4] Cross-sectional view of the rotary when the toner level in the developing unit is 100%. [Figure 5] Diagram showing the configuration of the magnetic material unit. [Figure 6]Cross-sectional view of the rotary when the toner level in the developing unit is 82%. [Figure 7] Cross-sectional view of the rotary when the toner level in the developing unit is 60%. [Figure 8] This figure shows an example of the relationship between elapsed time and the magnetic flux density detected by the magnetic flux detection unit. [Figure 9] A diagram showing an example of a toner quantity detection configuration. [Figure 10] This diagram shows an example of the relationship between the amount of toner in the developing unit and the maximum value of the magnetic flux detection signal output by the magnetic flux detection unit. [Figure 11] A diagram showing examples of the time evolution of magnetic flux detection signals and rotational phase detection signals. [Figure 12] Flowchart for determining toner quantity. [Figure 13] A figure showing another example of the time evolution of the magnetic flux detection signal and the rotational phase detection signal. [Figure 14] Another flowchart for the toner quantity determination process. [Figure 15] A diagram showing yet another example of the time evolution of the magnetic flux detection signal and the rotational phase detection signal. [Figure 16] A diagram showing an example of a rotary phase detection configuration. [Modes for carrying out the invention]

[0008] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0009] <First Embodiment> FIG. 1 illustrates an image forming apparatus 1 used for describing the embodiment. In the following description, the vertical direction when the image forming apparatus 1 is installed on a horizontal plane is defined as the z-direction. The direction intersecting the z-direction and aligned with the rotational axis 90C of the rotary 90 is defined as the y-direction. Further, the direction intersecting both the z-direction and the y-direction is defined as the x-direction. The x-direction and the y-direction are preferably horizontal directions. Moreover, the x-direction, y-direction, and z-direction are preferably mutually orthogonal.

[0010] An apparatus main body 1A of the image forming apparatus 1 includes a drum-shaped photoreceptor 2. Around the photoreceptor 2, a charging roller 3, a scanner 4 serving as an exposure apparatus, a cleaning unit 6, a rotary 90, and an intermediate transfer belt 10 are disposed. The rotary 90 accommodates developing units 50y, 50m, 50c, and 50k therein. The rotary 90 also includes trays 80y, 80m, 80c, and 80k which are support members. The trays 80y, 80m, 80c, and 80k are configured to hold cartridges 70y, 70m, 70c, and 70k that contain toner as a developer. The cartridges 70y, 70m, 70c, and 70k contain yellow, magenta, cyan, and black toners, and supply the toners to the developing units 50y, 50m, 50c, and 50k.

[0011] Note that the suffix characters "y", "m", "c", and "k" at the end of the reference numerals indicate that the color of the image formed by the member denoted by the reference numeral is yellow, magenta, cyan, and black. In the following description, when there is no need to distinguish the color of the image formed by the members, reference numerals without the suffix characters are used collectively.

[0012] During image formation, the photoreceptor 2 is driven to rotate in a counterclockwise direction as shown in the figure. The charging roller 3 uniformly charges the surface of the photoreceptor 2. The scanner 4 forms an electrostatic latent image for the yellow image on the photoreceptor 2 based on the image data for the yellow image. In order to develop the electrostatic latent image for the yellow image formed on the photoreceptor 2 with yellow toner, the rotary 90 is rotated in a clockwise direction as shown in the figure so that the developing roller 51y of the developing unit 50y faces the photoreceptor 2. In the following description, the position of the rotary 90 in which the developing roller 51y faces the photoreceptor 2 will be referred to as the "yellow developing position". Similar to the yellow developing position, the magenta developing position, cyan developing position and black developing position are defined.

[0013] The electrostatic latent image for the yellow image formed on the photoreceptor 2 is developed with yellow toner by the developing unit 50y, thereby forming a yellow image on the photoreceptor 2. The primary transfer roller 11 transfers the yellow image formed on the photoreceptor 2 to the intermediate transfer belt 10. Next, the rotary 90 is set to the magenta developing position to form a magenta image on the photoreceptor 2. The primary transfer roller 11 transfers the magenta image formed on the photoreceptor 2 onto the yellow image on the intermediate transfer belt 10. Thereafter, the cyan image and the black image are transferred to the intermediate transfer belt 10 in a similar manner. By transferring the black image to the intermediate transfer belt 10, the image to be transferred to the sheet S is formed on the intermediate transfer belt 10. The secondary transfer roller 12 and the cleaning device 13 are separated from the intermediate transfer belt 10 until the images of the four colors have been transferred to the intermediate transfer belt 10.

[0014] On the other hand, the sheet S accommodated in the cassette 300 is conveyed along a conveyance path provided in the apparatus main body 1A. A plurality of conveyance rollers for conveying the sheet S are provided along the conveyance path. The secondary transfer roller 12 transfers the image formed on the intermediate transfer belt 10 to the sheet S. The fixing device 40 fixes the image to the sheet S by heating and pressurizing the sheet S. Thereafter, the sheet S is discharged to the outside of the image forming apparatus 1. When forming a monochrome image on the sheet S, the rotary 90 is set to a black developing posture to form a black image on the photoreceptor 2, and this black image is transferred to the sheet S via the intermediate transfer belt 10.

[0015] The apparatus main body 1A is provided with a door 14 for replacing the cartridge 70. When replacing the cartridge 70, the rotary 90 is rotated to make the tray 80 holding the cartridge 70 to be replaced face the door 14. Then, the tray 80 is slid and moved in the direction of the door 14 so that the tray 80 protrudes from the rotary 90. The door 14 is configured to be opened when pushed by the tray 80, and to be closed when the tray 80 is accommodated inside the rotary 90. By moving the tray 80 to the outside of the apparatus main body 1A, the user can replace the cartridge 70. That is, the cartridge 70 is configured to be attachable to and detachable from the apparatus main body 1A. Further, the apparatus main body 1A is provided with a magnetic flux detection unit 102 for detecting the remaining amount of toner in the developing unit 50.

[0016] Figure 2 is an explanatory diagram of the developing unit 50 and the cartridge 70. The cartridge 70 has a toner frame 71. The toner frame 71 includes a toner accommodating portion 71a that accommodates toner, and a discharge opening 71b that communicates with the toner accommodating portion 71a. The developing unit 50 has a developing frame 53. The developing frame 53 is an accommodating member that accommodates toner, and includes a developing accommodating portion 53a and a receiving opening 53b that communicates with the developing accommodating portion 53a. Other members such as the developing roller 51 are provided inside the developing frame 53 of the developing unit 50, but are omitted in Figure 2 for the sake of simplifying the drawing.

[0017] When the cartridge 70 is in the mounting position relative to the developing frame 53, the discharge opening 71b faces the receiving opening 53b. In other words, the toner storage section 71a of the cartridge 70 and the developing storage section 53a of the developing unit 50 are in communication via the discharge opening 71b and the receiving opening 53b. Toner is supplied from the cartridge 70 to the developing unit 50 when at least a portion of the receiving opening 53b is located below at least a portion of the discharge opening 71b.

[0018] The cartridge 70 may have a sealing member (not shown) that covers the discharge opening 71b. The developing unit 50 may also have a sealing member (not shown) that covers the receiving opening 53b. The sealing members can suppress the outflow of toner from the discharge opening 71b and the receiving opening 53b even when the cartridge 70 is not installed in the developing unit 50.

[0019] Figure 3 is a perspective view of the rotary 90. Disc gears 92 are provided at both ends in the direction of the rotation axis 90C. Rotary drive gears 93 are provided at both ends of the oscillating shaft 91. The driving force of a motor (not shown) is transmitted to one of the rotary drive gears 93. This driving force is transmitted to the other rotary drive gear 93 via the oscillating shaft 91. The two rotary drive gears 93 also transmit driving force to their corresponding disc gears 92. The rotary 90 rotates together with the disc gears 92.

[0020] The rotary 90 is supported so as to be able to swing around the pivot axis 91. The rotary 90 is biased by a biasing member (not shown) so that the developing roller 51 of the developing unit 50, which is in the developing position, moves toward the photoreceptor 2 around the pivot axis 91. As a result, in the developing position for each color, the developing roller 51 comes into contact with the photoreceptor 2. In addition, as shown in Figure 3, rotary cams 90e are provided at each end of the rotary 90. The rotary cams 90e are configured to come into contact with rollers (not shown) that are supported by the frame of the main body 1A of the device. As a result, when the rotary 90 is rotated, the rotary 90 swings. This swinging motion allows the developing roller 51 to move away from the photoreceptor 2.

[0021] During image formation, the total amount of toner contained in the developing unit 50 and cartridge 70 decreases. When the amount of toner in cartridge 70 decreases, it becomes difficult to supply toner from cartridge 70 to the developing unit 50, and the amount of toner in the developing unit 50 decreases. A low amount of toner in the developing unit 50 can cause image defects. For this reason, the image forming apparatus 1 is configured to detect the remaining amount of toner in the developing unit 50. A low amount of toner in the developing unit 50 means that the amount of toner in cartridge 70 is low. Therefore, when the image forming apparatus 1 detects that the amount of toner in the developing unit 50 is low, it notifies the user to replace cartridge 70.

[0022] The following describes a configuration for detecting the amount of toner contained in the developing frame 53 of the developing unit 50. In the following description, the amount of toner contained in the developing frame 53 of the developing unit 50 will also be referred to as "the amount of toner contained in the developing unit 50". Figure 4 is a cross-sectional view of the rotary 90. As already explained, the rotary 90 has developing units 50y, 50m, 50c, and 50k. The developing units 50y, 50m, 50c, and 50k have magnetic material units 103y, 103m, 103c, and 103k.

[0023] The shaded areas in Figure 4 indicate the areas where toner is present. In Figure 4, each developing unit 50 contains the maximum amount of toner that can be accommodated in the developing frame 53. In the following explanation, the amount of toner contained in the developing frame 53 will be expressed as a percentage (%) of the maximum amount that can be accommodated in the developing frame 53. In other words, Figure 4 shows a cross-section of the rotary 90 when the toner amount in each developing unit 50 is 100%.

[0024] In the following description, the rotation axis 90C of the rotary 90, that is, the direction from the center of the rotary 90 toward the outer circumference of the rotary 90, will be referred to as the radial direction. In the following description, the member at the end of the developing frame 53 on the downstream side in the radial direction will be referred to as the downstream member 53rd, and the member at the end of the developing frame 53 on the upstream side will be referred to as the upstream member 53ru. In the radial direction, the distance between the upstream member 53ru and the rotation axis 90C is smaller than the distance between the downstream member 53rd and the rotation axis 90C. Also, the downstream member 53rd and the upstream member 53ru face each other in the radial direction. Furthermore, the downstream member 53rd and the upstream member 53ru extend in a direction intersecting the radial direction.

[0025] The magnetic flux detection unit 102 is positioned above the rotation axis 90C in the vertical direction. In this embodiment, as shown in Figure 4, the magnetic flux detection unit 102 is positioned above the uppermost position of the rotary 90 in the vertical direction, which is the rotary upper end 90eu. The magnetic flux detection unit 102 is positioned above the rotary 90 in the vertical direction and opposite the rotary upper end 90eu. In other words, when viewed in the direction of the rotation axis 90C, the magnetic flux detection unit 102, the rotary upper end 90eu, and the rotation axis 90C are aligned in a straight line.

[0026] Figure 5 is a perspective view of the magnetic unit 103. The magnetic unit 103 is attached to the downstream member 53rd of the developing frame 53. More specifically, the fixing member 107 of the magnetic unit 103 is attached to the downstream member 53rd. The fixing member 107 supports the rotation shaft 106 so that it can rotate in the R direction in Figure 5. The axial direction of the rotation shaft 106 is parallel to, for example, the direction of the rotation axis 90C of the rotary 90. The support member 100 is attached to the rotation shaft 106 so as to rotate with the rotation shaft 106. The support member 100 supports a permanent magnet 101, which is a magnetic material. Thus, the permanent magnet 101 is supported on the downstream member 53rd so as to be rotatable about the rotation shaft 106 as the center of rotation. The permanent magnet 101 may be, for example, a neodymium magnet. The permanent magnet 101 has a first surface on the support member 100 side and a second surface on the opposite side from the first surface. The first face is either the north pole or the south pole, and the second face is the other of the north pole or the south pole. In the following explanation, the first face will be considered the north pole and the second face the south pole.

[0027] The change in the orientation of the magnetic material unit 103 due to the rotation of the rotary 90 will be explained using Figure 6. Figure 6 shows a cross-section of the rotary 90 when the toner amount of each developing unit 50 is 82%. Figure 6 is a view in the direction of the rotation axis 90C. In the following explanation, the state in which a developing unit 50 is at the position of developing unit 50k in Figure 6 will be referred to as the first orientation of the developing unit 50. Furthermore, the state in which a developing unit 50 is at the position of developing unit 50c in Figure 6 will be referred to as the second orientation of the developing unit 50. Furthermore, the state in which a developing unit 50 is at the position of developing unit 50m in Figure 6 will be referred to as the third orientation of the developing unit 50. Furthermore, the state in which a developing unit 50 is at the position of developing unit 50y in Figure 6 will be referred to as the fourth orientation of the developing unit 50. Figure 6 shows the development unit 50k in the first position, development unit 50c in the second position, development unit 50m in the third position, and development unit 50y in the fourth position. The development unit 50 cyclically transitions between the first position, second position, third position, fourth position, and first position due to the rotation of the rotary. In the following, the straight line connecting the rotation axis 90C and the magnetic flux detection unit 102, viewed in the direction of the rotation axis 90C, will be denoted as straight line L1. Also, the line segment connecting the rotation axis 90C and the magnetic flux detection unit 102 will be denoted as line segment L1.

[0028] In the first orientation of the developing unit 50, the magnetic material unit 103 is located above the rotation axis 90C. In the first orientation of the developing unit 50, the rotation axis 90C, the permanent magnet 101, and the magnetic flux detection unit 102 are all located on a straight line L1 when viewed in the direction of the rotation axis 90C. In the following description, the timing at which the permanent magnet 101 of the developing unit 50 is located on the line segment connecting the rotation axis 90C and the magnetic flux detection unit 102, when viewed in the direction of the rotation axis 90C, will be referred to as the "parallel timing" of the developing unit 50.

[0029] As the rotary 90 rotates clockwise in the diagram, the developing unit 50 transitions from the first position to the second position. The toner contained in the developing unit 50 moves from the upstream member 53ru side to the downstream member 53rd side due to gravity. The magnetic unit 103 also rotates due to gravity, moving closer to the downstream member 53rd. This rotation is restricted by the permanent magnet 101 and support member 100 of the magnetic unit 103 coming into contact with the downstream member 53rd.

[0030] As the rotary 90 is further rotated clockwise in the diagram, the developing unit 50 transitions from the second to the third position, and the toner contained in the developing unit 50 moves toward the downstream member 53rd. In the second position, the rotation of the magnetic unit 103 is restricted by the downstream member 53rd, so in the third position, the permanent magnet 101 and the support member 100 remain in contact with the downstream member 53rd.

[0031] As the rotary 90 is further rotated clockwise in the diagram, the developing unit 50 transitions from the third to the fourth position. The toner contained within the developing unit 50 moves due to gravity from the downstream member 53rd to the upstream member 53ru. The magnetic unit 103 also rotates due to gravity, moving closer to the upstream member 53ru. This rotation is restricted by the contact between the permanent magnet 101 and the support member 100 of the magnetic unit 103 and the toner. The position at which the rotation of the magnetic unit 103 is restricted by contact with the toner depends on the amount of toner in the developing unit 50.

[0032] As the rotary 90 is further rotated clockwise in the diagram, the developing unit 50 transitions from the fourth position to the first position. The toner contained in the developing unit 50 moves toward the upstream member 53ru due to gravity. The magnetic unit 103 also rotates toward the upstream member 53ru due to gravity, but this rotation is restricted by the permanent magnet 101 and support member 100 of the magnetic unit 103 contacting the toner. The position at which the rotation of the magnetic unit 103 is restricted by contact with the toner depends on the amount of toner in the developing unit 50.

[0033] In other words, in parallel timing, the distance between the permanent magnet 101 and the magnetic flux detection unit 102 changes according to the amount of toner in the developing storage unit 53a.

[0034] Next, the relationship between the amount of toner in the developing unit 50 and the magnetic flux density passing through the magnetic flux detection unit 102 will be explained. Figure 7 shows a cross-section of the rotary 90 when the amount of toner in each developing unit is 60%. As shown in Figures 4, 6, and 7, the position of the permanent magnet 101 in the developing unit in the first position moves closer to the downstream member 53rd as the amount of toner contained increases. In other words, the position of the permanent magnet 101 in the developing unit in the first position moves closer to the magnetic flux detection unit 102 as the amount of toner contained increases. The straight line D1 in Figure 6 shows the distance between the permanent magnet 101 and the magnetic flux detection unit 102 when the amount of toner in the developing unit is 82%. The straight line D2 in Figure 7 shows the distance between the permanent magnet 101 and the magnetic flux detection unit 102 when the amount of toner in the developing unit is 60%. As is clear from the figures, the length of the straight line D1 is shorter than the length of the straight line D2.

[0035] Furthermore, the angle between the normal direction of the second surface of the permanent magnet 101 and the straight line L1 approaches 0 as the amount of toner stored increases. Arrow N1 in Figure 6 indicates the normal direction of the second surface of the permanent magnet 101 when the toner amount in the developing unit is 82%. Arrow N2 in Figure 7 indicates the normal direction of the second surface of the permanent magnet 101 when the toner amount in the developing unit is 60%. As is clear from the figures, the angle between the direction of arrow N1 and the straight line L1 (the direction from the rotation axis 90C toward the magnetic flux detection unit 102) is smaller than the angle between the direction of arrow N2 and the straight line L1.

[0036] Figure 8 shows an example of the time change in magnetic flux density passing through the magnetic flux detection unit 102 when the rotary 90 is rotated at a speed of one revolution per second. The horizontal axis in Figure 8 represents the elapsed time since the rotary 90 started rotating. Figure 8 shows the time change in magnetic flux density over a period of approximately 250 ms, that is, the period during which the rotary 90 rotates approximately 1 / 4 of a turn. During the period during which the rotary 90 rotates approximately 1 / 4 of a turn, one developing unit 50 passes opposite the magnetic flux detection unit 102. In other words, the period shown in Figure 8 includes the parallel timing of one developing unit 50. The vertical axis represents the magnetic flux density passing through the magnetic flux detection unit 102. That is, the vertical axis represents the magnetic flux density detected by the magnetic flux detection unit 102. The magnetic flux density passing through the magnetic flux detection unit 102 varies depending on the orientation of the developing unit 50 and is maximum near the parallel timing of the developing unit 50. As shown in Figure 8, the maximum magnetic flux density passing through the magnetic flux detection unit 102 is approximately 24 mT when the toner amount is 100%, while it is approximately 1 mT when the amount is 60%. In this way, the amount of toner contained in the developing unit 50 can be determined by the magnetic flux density passing through the magnetic flux detection unit 102.

[0037] Figure 9 shows an example of a toner quantity measurement configuration for the developing unit 50. In Figure 9, Vcc is the operating voltage of the CPU 510, magnetic flux detection unit 102, and phase detection unit 801, supplied from a power supply unit (not shown), and is, for example, 3.3V. The controller 600 controls the entire image forming apparatus 1. The display unit 700 provides an input / output interface to the user. When a print job is submitted via a network from, for example, a host computer (not shown), the controller 600 controls image formation on the sheet S as described using Figure 1. The controller 600 also controls the display of information on the display unit 700, etc. The CPU 510 of the engine control unit 500 determines the amount of toner in the developing unit 50 by executing a control program stored in, for example, a ROM 520, which is an example of non-volatile memory. In other words, the CPU 510 functions as a toner quantity determination unit. In this embodiment, there is only one CPU 510, but the image forming apparatus 1 may have at least one other CPU that determines the amount of toner. The CPU 510 uses RAM 530, an example of volatile memory, as a work area. RAM 530 is a storage unit. RAM 530 may also store information such as the amount of toner in the developing unit 50 as determined by the CPU 510.

[0038] The magnetic flux detection unit 102 includes a sensor for detecting a magnetic field. The magnetic flux detection unit 102 has, for example, a linear output Hall IC sensor. The magnetic flux detection unit 102 outputs a magnetic flux detection signal Vout to the CPU 510, which indicates the detection result of the magnetic flux density penetrating in the vertical direction (z direction, as in Figure 7). The value of Vout is, for example, proportional to the magnitude of the magnetic flux density detected by the magnetic flux detection unit 102. Figure 10 shows, for example, an example of the relationship between the amount of toner in the developing unit 50k and the maximum value (peak value) of the magnetic flux detection signal output by the magnetic flux detection unit 102. The CPU 510 stores the value of the magnetic flux detection signal Vout in the RAM 530. The information showing the example relationship between the amount of toner in the developing unit 50k and the maximum value of the magnetic flux detection signal output by the magnetic flux detection unit 102, as shown in Figure 10, is created in advance and stored, for example, in the ROM 520.

[0039] The phase detection unit 801 is provided to detect the rotational phase of the rotary 90. Figure 16 shows an example of a configuration for detecting the rotational phase of the rotary 90. The phase detection unit 801 is, for example, a photointerrupter and has a light-emitting element and a light-receiving element. The light-emitting element and the light-receiving element of the phase detection unit 801 are provided on opposite sides of the detected member 802. The detected member 802 is configured to rotate once when the rotary 90 rotates once, via a transmission mechanism not shown in Figure 3, etc. A notch 803 is provided on the outer circumference of the detected member. When the notch 803 is between the light-emitting element and the light-receiving element of the phase detection unit 801, the light-receiving element receives light from the light-emitting element. On the other hand, when the notch 803 is not between the light-emitting element and the light-receiving element of the phase detection unit 801, the detected member 802 blocks the light from the light-emitting element, and therefore the light-receiving element does not receive light from the light-emitting element. Therefore, the CPU 510 can detect that the rotation phase of the rotary 90 is a predetermined phase based on the timing at which the light-receiving element receives light from the light-emitting element. In the example shown in Figure 16, the detected member 802 is configured to block light from the light-emitting element for most of the time it takes for the rotary 90 to complete one rotation. However, the periods during which the detected member 802 blocks light from the light-emitting element and the periods during which it does not can be arbitrarily set.

[0040] In the following explanation, the rotational phase of the rotary 90 at the timing when the light-receiving element transitions from a state where it is receiving light from the light-emitting element to a state where it is not receiving light will be referred to as the reference phase, and the orientation of the rotary 90 at that time will be referred to as the "detected orientation". The phase detection unit 801 outputs a rotational phase detection signal Vrot to the CPU 510, which indicates the detection result of the detected member 802, or more specifically, the detection result of the light by the light-receiving element. The rotational phase detection signal Vrot is also a signal that indicates the point in time when the orientation of the rotary 90 is the detected orientation (detection time). For example, when the light-receiving element of the phase detection unit 801 receives light, it sets the rotational phase detection signal Vrot to a high level (Hi), and otherwise sets the rotational phase detection signal Vrot to a low level (Lo). In this embodiment, when the rotary 90 is rotated by an angle θ in the clockwise direction as shown in Figure 7 after the rotation phase detection signal Vrot switches from a high level to a low level, the detected member 802 is positioned such that the measurement value of the magnetic flux density from the permanent magnet 101 of the developing unit 50k containing 100% toner, as measured by the magnetic flux detection unit 102, is maximized. The angle θ may be, for example, 45°. In other words, when the rotary in the detected position is rotated by about 45°, the magnetic flux detection unit 102 can detect the magnetic flux density from the permanent magnet 101 of the developing unit 50k most strongly.

[0041] Figure 11 shows the time evolution of the magnetic flux detection signal Vout and the rotational phase detection signal Vrot when the rotary 90 is rotated at a rotational speed of 1 revolution / second (hereafter, 1 rps). When the rotary 90 is rotated at 1 rps, the detected member 802 is configured such that the rotational phase detection signal Vrot is at a high level for about 20 ms each time the rotary 90 completes one rotation. The toner amount detection period for each developing unit 50 is determined based on the timing when the rotational phase detection signal Vrot changes from a high level to a low level. Period determination information indicating the start and end timings of each detection period from the timing when the rotational phase detection signal Vrot changes from a high level to a low level is stored in the ROM 520 in advance. The detection period 1501 shown in Figure 11 is the detection period for developing unit 50k, the detection period 1502 is the detection period for developing unit 50y, the detection period 1503 is the detection period for developing unit 50m, and the detection period 1504 is the detection period for developing unit 50c. The detection period corresponding to the developing unit 50 is the period including the parallel timing of the developing unit 50. In this embodiment, the length of detection periods 1501 to 1504 is 250 ms each. In other words, in this embodiment, the sum of detection periods 1501 to 1504 is the time required for one rotation of the rotary 90. To put it another way, detection periods 1501 to 1504 are each equal to the period during which the rotary 90 rotates by 90 degrees.

[0042] Near the parallel timing of each developing unit 50, the magnetic flux detection signal Vout from the magnetic flux detection unit 102 may reach a peak, as shown in Figure 11 as Vpk_1501 to Vpk_1504.

[0043] Figure 4 shows the case where the developing unit 50k is in the first position and the developing unit 50y is in the fourth position. Note that the state in Figure 4 corresponds to the detection period 1501. At this time, the shortest distance D3 between the magnetic flux detection unit 102 and the permanent magnet 101 of the developing unit 50k is shorter than the shortest distance D4 between the magnetic flux detection unit 102 and the permanent magnet 101 of the developing unit 50y. Subsequently, at the start of the detection period 1502, the developing unit 50k is in the second position and the developing unit 50y is in the first position. Therefore, the state obtained by replacing the developing unit 50k in Figure 4 with the developing unit 50y and the developing unit 50c in Figure 4 with the developing unit 50k corresponds to the detection period 1502. At this time, the shortest distance D3 between the magnetic flux detection unit 102 and the permanent magnet 101 of the developing unit 50y is shorter than the shortest distance D5 between the magnetic flux detection unit 102 and the permanent magnet 101 of the developing unit 50k.

[0044] Figure 12 is a flowchart of the determination process performed by the CPU 510 to determine the amount of toner in each developing unit 50. In S10, the CPU 510 rotates the rotary 90 at a predetermined rotational speed, for example, 1 rps. In S11, the CPU 510 initializes the timer to, for example, 0. In S12, the CPU 510 waits until the rotational phase detection signal Vrot falls from a high level to a low level.

[0045] When the rotation phase detection signal Vrot falls from a high level to a low level, the CPU 510 starts counting the elapsed time using a timer in S13. Subsequently, in S14, the CPU 510 stores the value of the magnetic flux detection signal Vout in the RAM 530, associating it with the timer value (count value) of the timer, at predetermined intervals. The predetermined interval may be, for example, 1 ms. The processing in S14 is performed from the moment the rotation phase detection signal Vrot falls from a high level to a low level until the rotary 90 completes one rotation. Alternatively, the value of the magnetic flux detection signal Vout may be stored in the RAM 530 as being associated with period information indicating the detection period, rather than with the timer value of the timer.

[0046] In S15, the CPU 510 determines, based on the timer values ​​recorded in the RAM 530, which of the detection periods 1501 to 1504 the value of the magnetic flux detection signal Vout stored in the RAM 530 belongs to. For example, the value of the magnetic flux detection signal Vout associated with a timer value of 1ms to 250ms belongs to detection period 1501, and the value of the magnetic flux detection signal Vout associated with a timer value of 251ms to 500ms belongs to detection period 1502. Similarly, the value of the magnetic flux detection signal Vout associated with a timer value of 501ms to 750ms belongs to detection period 1503, and the value of the magnetic flux detection signal Vout associated with a timer value of 751ms to 1000ms belongs to detection period 1504. If the value of the magnetic flux detection signal Vout stored in the RAM 530 is associated with period information, the CPU 510 determines the detection period to which each magnetic flux detection signal Vout belongs from the period information. The CPU 510 determines the peak value (maximum value) of the magnetic flux detection signal Vout for each detection period 1501 to 1504. In S16, the CPU 510 determines the amount of toner in each developing unit 50 based on the peak values ​​for each detection period 1501 to 1504 and stores it in the RAM 530. For determining the amount of toner, information showing the relationship between the peak value and the amount of toner in each developing unit 50, i.e., the information shown in Figure 10, which is stored in the ROM 520, is used. The controller 600 can display the information showing the amount of toner in each developing unit 50 stored in the RAM 530 on, for example, the display unit 700. The controller 600 can compare the amount of toner in each developing unit 50 stored in the RAM 530 with a threshold value and determine whether the amount of toner in each developing unit 50 is less than the threshold value. If the amount of toner in a developing unit 50 is less than the threshold value, the controller 600 may determine that the cartridge 70 that supplies toner to the developing unit 50 needs to be replaced. In this case, the controller 600 can display on the display unit 700 that the cartridge 70 needs to be replaced. The display unit 700 may also display information regarding the toner quantity determination result, in addition to the toner quantity information. The threshold value used for comparison with the toner quantity may be the same or different for each developing unit 50.

[0047] In this embodiment, each detection period was identified by counting the elapsed time since the rotation phase detection signal Vrot switched from a high level to a low level using a timer. However, instead of a timer, each detection period can also be identified by the amount of rotation of the motor driving the rotary 90.

[0048] Furthermore, while the toner amount was determined based on the peak value of the magnetic flux detection signal Vout during each detection period, it is also possible to configure the system to determine the toner amount based on the integral value of the magnetic flux detection signal Vout during the detection period, or on calculated values ​​for multiple Vout values ​​for the entire or a part of the detection period.

[0049] Furthermore, although a linear output Hall IC sensor is used as the magnetic flux detection unit 102 in this embodiment, a switch output sensor whose output reverses when the magnetic flux density exceeds a predetermined threshold can also be used as the magnetic flux detection unit 102. When a switch output Hall IC sensor is used, the amount of toner in the developing unit 50 can be determined based on the period during which the output reverses.

[0050] Furthermore, in this embodiment, the frequency of the rotation phase detection signal Vrot switching from a high level to a low level was once per rotation of the rotary 90. In other words, in this embodiment, the phase detection unit 801 detected one rotation phase (one reference phase) of the rotary 90. However, the phase detection unit 801 can also be configured to detect multiple rotation phases of the rotary 90. Also, in this embodiment, the toner amount of each developing unit 50 is determined sequentially by rotating the rotary 90 once, but it is also possible to configure the system to determine only the toner amount of one developing unit 50. For example, when a certain developing unit 50 transitions to the developing position, the system can be configured to determine only the toner amount of that developing unit 50.

[0051] As described above, by determining the detection period 1501 to 1504 for the toner amount of each developing unit 50 based on the detection result of the detected member 802 by the phase detection unit 801, the toner amount of each developing unit 50 can be determined with high accuracy.

[0052] <Second Embodiment> Next, the second embodiment will be described, focusing on the differences from the first embodiment. For example, in the first embodiment, the value of the magnetic flux detection signal Vout was stored in the RAM 530 every 1ms. Therefore, it was necessary to reserve a memory area in the RAM 530 to store 1000 Vout values. On the other hand, as shown in Figure 11, in each of the detection periods 1501 to 1504, the magnetic flux from the permanent magnet 101 penetrates the magnetic flux detection unit 102, and the period during which the value of the magnetic flux detection signal Vout changes as a result is limited.

[0053] Therefore, in this embodiment, as shown in Figure 13, the detection period of each developing unit 50 is made shorter than in the first embodiment. The detection period 1701 of developing unit 50k is, for example, from 81ms to 180ms. The detection period 1702 of developing unit 50y is, for example, from 331ms to 430ms. The detection period 1703 of developing unit 50m is, for example, from 581ms to 680ms. The detection period 1704 of developing unit 50c is, for example, from 831ms to 930ms. Note that the timing when the rotation phase detection signal Vrot changes from a high level to a low level is set to 0ms. In this way, in this embodiment, the sum of the detection periods 1701 to 1704 is shorter than the time it takes for the rotary 90 to complete one rotation. In other words, each of the detection periods 1701 to 1704 is shorter than the time it takes for the rotary 90 to rotate 90 degrees. In this way, by limiting the period for which the value of the magnetic flux detection signal Vout is stored in RAM 530, the amount of RAM 530 that needs to be reserved to store the value of Vout can be reduced.

[0054] Figure 14 is a flowchart of the determination process performed by the CPU 510 to determine the toner amount of each developing unit 50. Note that the same step numbers are used for processing steps similar to those in the flowchart of the first embodiment shown in Figure 12, and their explanations are omitted. In this embodiment, when the timer starts counting in S13, the CPU 510, in S20, repeatedly stores the value of the magnetic flux detection signal Vout in the RAM 530 in association with the timer value during each of the detection periods 1701 to 1704 at predetermined intervals. In this embodiment, the value of the magnetic flux detection signal Vout is not stored in the RAM 530 during periods that are not detection periods. The detection periods 1701 to 1704 are determined to include the parallel timing of each developing unit 50, taking various margins into consideration. The detection periods 1701 to 1704 are determined based on the timing when the rotation phase detection signal Vrot switches from a high level to a low level.

[0055] In this embodiment, the area of ​​RAM 530 that needs to be reserved to store the Vout value can be reduced compared to the first embodiment. Furthermore, by shortening the detection period used for determining the toner amount, the influence of disturbances that occur outside the detection period can be excluded.

[0056] In this embodiment, the lengths of the detection periods 1701 to 1704 are the same, but the lengths of the detection periods 1701 to 1704 can also be different. Furthermore, as shown in Figure 15, the phase detection unit 801 and the detected member 802 can be configured to output a high level as the rotation phase detection signal Vrot during the detection periods 1701 to 1704. In other words, the phase detection unit 801 and the detected member 802 can be configured to detect the rotation phase corresponding to the start and end timings of each detection period 1701 to 1704, and the detection of these rotation phases can be notified to the CPU 510 by the rotation phase detection signal Vrot. In this case, the CPU 510 can determine the start and end timings of each detection period based on the rotation phase detection signal Vrot.

[0057] In Figure 15, the phase detection unit 801 detects the rotational phase of the rotary 90 at the start and end timings of each detection period. However, the system can be configured to detect the rotational phase of the rotary 90 at a timing predetermined period earlier than the start and end timings of each detection period. In this case, the CPU 510 determines the start and end timings of the detection period to be predetermined periods later than the timing notified by the phase detection unit 801. Furthermore, in Figure 15, two rotational phases are detected for each detection period: one associated with the start timing and one associated with the end timing. However, the system can also be configured to determine the start and end timings of a detection period based on one rotational phase associated with that detection period. Moreover, the system can also be configured to determine the start and end timings of two detection periods based on one rotational phase associated with two detection periods. In other words, the system can arbitrarily determine which detection period's start or end timing is determined based on the detected rotational phases.

[0058] [Other embodiments] The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0059] This embodiment includes the following configuration. (Composition 1) It comprises a first storage section for storing the first developer and a second storage section for storing the second developer, and a rotating rotary, A first permanent magnet is supported in the first housing so as to be movable inside the first housing, A second permanent magnet is supported in the second housing so as to be movable inside the second housing, A first sensor provided outside the rotary, which detects a magnetic field and outputs a signal, A second sensor that detects the rotary in the detected position, One or more CPUs, It has, If the time when the second sensor detects the detected posture of the rotary is defined as the detection time, the time when one hour has elapsed from the detection time is defined as the first time point, and the time when two hours have elapsed from the detection time is defined as the second time point, At the aforementioned first time point, the shortest distance between the first permanent magnet and the first sensor is shorter than the shortest distance between the second permanent magnet and the first sensor. At the second time point, the shortest distance between the second permanent magnet and the first sensor is shorter than the shortest distance between the first permanent magnet and the first sensor. Based on the signal at the first time point, one or more CPUs determine that the amount of the first developer in the first storage unit is less than the first threshold. Based on the signal at the second time point, one or more CPUs determine that the amount of the second developer in the second storage unit is less than the second threshold. An image forming apparatus characterized by the following: (Configuration 2) The first sensor outputs the signal during the first period including the first time point. The first sensor outputs the signal during the second period, which is a period after the first period and includes the second time point. The one or more CPUs determine the timing of the first period and the timing of the second period based on the timing at which the second sensor detects the detected posture of the rotary. The image forming apparatus according to configuration 1, characterized in that it is a picture forming apparatus. (Composition 3) The first period and the second period are each shorter than the time it takes for the rotary to rotate 90 degrees. The image forming apparatus according to configuration 2, characterized in that... (Composition 4) The one or more CPUs determine the timing of the first time point and the second time point by counting a predetermined time after the detection time. An image forming apparatus according to any one of configurations 1 to 3, characterized by the above. (Composition 5) The one or more CPUs determine the timing of the first time point and the second time point based on information regarding the amount of rotation of the rotary after the detection time point. An image forming apparatus according to any one of configurations 1 to 3, characterized by the above. (Composition 6) The first parallel timing is defined as the case where the first permanent magnet is located on the line segment connecting the rotation axis and the first sensor, viewed in the direction of the rotation axis of the rotary. When the second parallel timing is defined as the case where the second permanent magnet is located on the line segment connecting the rotation axis and the first sensor, viewed in the direction of the rotation axis of the rotary, The first period includes the first parallel timing, The second period includes the second parallel timing, The image forming apparatus according to configuration 2 or 3, characterized by the above. (Composition 7) It is further equipped with a memory unit for storing information, The storage unit does not store information based on the signal output by the first sensor between the first period and the second period. The image forming apparatus according to configuration 3, characterized in that it is a picture forming apparatus. (Composition 8) The rotary includes a detection unit, The second sensor detects the part of the rotary that is in the detected position, An image forming apparatus according to any one of configurations 1 to 7, characterized by the above. (Composition 9) The first developer and the second developer have different developer colors. An image forming apparatus according to any one of configurations 1 to 8, characterized by the above. (Composition 10) The first sensor is located above the rotation axis of the rotary in the vertical direction. An image forming apparatus according to any one of configurations 1 to 9, characterized by the above.

[0060] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0061] 90: Rotary, 50y, 50m, 50c, 50k: Developing unit, 53y, 53m, 53c, 53k: Developing frame, 101: Permanent magnet, 102: Magnetic flux detection unit, 801: Rotation phase detection unit, 510: CPU

Claims

1. It comprises a first storage section for storing the first developer and a second storage section for storing the second developer, and a rotating rotary, A first permanent magnet is supported in the first housing so as to be movable inside the first housing, A second permanent magnet is supported in the second housing so as to be movable inside the second housing, A first sensor provided outside the rotary, which detects a magnetic field and outputs a signal, A second sensor that detects the rotary in the detected position, One or more CPUs, It has, If the time when the second sensor detects the detected posture of the rotary is defined as the detection time, the time when one hour has elapsed from the detection time is defined as the first time point, and the time when two hours have elapsed from the detection time is defined as the second time point, At the aforementioned first time point, the shortest distance between the first permanent magnet and the first sensor is shorter than the shortest distance between the second permanent magnet and the first sensor. At the second time point, the shortest distance between the second permanent magnet and the first sensor is shorter than the shortest distance between the first permanent magnet and the first sensor. Based on the signal at the first time point, one or more CPUs determine that the amount of the first developer in the first storage unit is less than the first threshold. Based on the signal at the second time point, one or more CPUs determine that the amount of the second developer in the second storage unit is less than the second threshold. An image forming apparatus characterized by the following:

2. The first sensor outputs the signal during the first period including the first time point. The first sensor outputs the signal during the second period, which is a period after the first period and includes the second time point. The one or more CPUs determine the timing of the first period and the timing of the second period based on the timing at which the second sensor detects the detected posture of the rotary. The image forming apparatus according to feature 1.

3. The first period and the second period are each shorter than the time it takes for the rotary to rotate 90 degrees. The image forming apparatus according to feature 2.

4. The one or more CPUs determine the timing of the first time point and the second time point by counting a predetermined time after the detection time. The image forming apparatus according to feature 1.

5. The one or more CPUs determine the timing of the first time point and the second time point based on information regarding the amount of rotation of the rotary after the detection time point. The image forming apparatus according to feature 1.

6. The first parallel timing is defined as the case where the first permanent magnet is located on the line segment connecting the rotation axis and the first sensor, viewed in the direction of the rotation axis of the rotary. When the second parallel timing is defined as the case where the second permanent magnet is located on the line segment connecting the rotation axis and the first sensor, viewed in the direction of the rotation axis of the rotary, The first period includes the first parallel timing, The second period includes the second parallel timing, The image forming apparatus according to feature 2.

7. It is further equipped with a memory unit for storing information, The storage unit does not store information based on the signal output by the first sensor between the first period and the second period. The image forming apparatus according to feature 3.

8. The rotary includes a detection unit, The second sensor detects the part of the rotary that is in the detected position, The image forming apparatus according to any one of claims 1 to 7.

9. The first developer and the second developer have different developer colors. The image forming apparatus according to any one of claims 1 to 7.

10. The first sensor is located above the rotation axis of the rotary in the vertical direction. The image forming apparatus according to any one of claims 1 to 7.

Images