Drive control device and image forming apparatus

Abstract

To effectively reduce an operating sound when a solenoid is used in combination with a driving force transmission mechanism.SOLUTION: A drive control device comprises: a movable member that is displaceable between a first position and a second position; a solenoid that displaces the movable member from the first position to the second position by magnetic force; control means that controls power supply to the solenoid; and a transmission mechanism that makes a state transition according to the position of the movable member. The transmission mechanism transmits the driving force of a motor to a member to be driven in one of a first state and a second state, and does not transmit the driving force to the member to be driven in the other. When the solenoid displaces the movable member, the control means supplies current to the solenoid at a first duty ratio so that the movable member is displaced from the first position in a first period, and supplies current to the solenoid at a second duty ratio lower than the first duty ratio in a second period after the first period.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a drive control device and an image forming apparatus.

Background Art

[0002] Conventionally, in an image forming apparatus that forms an image on a sheet, a solenoid has been used as an actuator that converts electrical energy into mechanical energy. In particular, for transmitting and blocking the driving force to components such as rollers, drums, and belts, the solenoid is used in combination with some driving force transmission mechanism. Patent Document 1 discloses a technique for switching between a transmission state in which a driving force is transmitted and a blocking state in which the transmission of the driving force is blocked by causing a plunger displaced by the magnetic force of the solenoid to swing an arm member and engage the tip of the arm member with an internal gear of a planetary gear mechanism.

[0003] Although the solenoid is a convenient actuator, the operating noise caused by the collision of a member that moves by the magnetic force of the solenoid with other members may give discomfort to the user. Patent Document 2 discloses a technique for reducing the operating noise caused by the collision between a plunger and a connecting member when lowering a pickup roller toward a document. The technique disclosed in Patent Document 2 changes the period of a pulse signal supplied to the solenoid so that the pulling force of the solenoid and the mechanical load are balanced, thereby suppressing the displacement speed of the plunger.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when a solenoid is used in combination with a driving force transmission mechanism, since the load changes discontinuously during the transition between the transmission state and the cutoff state in which the driving force is transmitted, the operating noise may not be sufficiently reduced by the technique disclosed in Patent Document 2.

[0006] Therefore, an object of the present invention is to effectively reduce the operating noise when a solenoid is used in combination with a driving force transmission mechanism.

Means for Solving the Problems

[0007] According to one aspect, a movable member displaceable between a first position and a second position, a solenoid that displaces the movable member in the first position to the second position by magnetic force, control means for controlling the supply of current from a power source to the solenoid, and a transmission mechanism that transitions between a first state and a second state according to the position of the movable member, wherein in one of the first state and the second state, the driving force of the motor is transmitted to the driven member, and in the other of the first state and the second state, the driving force of the motor is not transmitted to the driven member, the transmission mechanism, and the control means, when the solenoid displaces the movable member from the first position to the second position, In the third period, supply current to the solenoid at a third duty ratio that is lower than the first duty ratio and higher than the second duty ratio. In a fourth period after the third period, supply current to the solenoid at a fourth duty ratio that is lower than the third duty ratio. After the fourth period such that the movable member is displaced from the first position toward the second position in a first period the the solenoid is supplied with current at a first duty ratio, and in a second period that starts after the first period and before the movable member reaches the second position, a second duty ratio lower than the first duty ratio the A drive control device is provided that supplies current to the solenoid. An image forming apparatus including the drive control device and an image forming unit that forms an image on a sheet is also provided.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to effectively reduce the operating noise when a solenoid is used in combination with a driving force transmission mechanism.

Brief Description of the Drawings

[0009]

Figure 1A

Figure 1B

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6A

Figure 6B

Figure 6C

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential to the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

[0011] <1. State switching of the transmission mechanism using a solenoid> FIGS. 1A and 1B are explanatory diagrams of the state switching of the transmission mechanism using a solenoid. In the illustrated example, the solenoid 10 generates a magnetic force by being supplied with current from a power source (not shown). FIG. 1A shows a state where the solenoid 10 is not powered, and FIG. 1B shows a state where the solenoid 10 is powered.

[0012] The first movable member 11 is a plate-like member pivotally supported by a fulcrum 10a provided on the housing of the solenoid 10 and is pivotable around the fulcrum 10a. In the figure, the first end 11a of the first movable member 11 is on the right side of the fulcrum 10a, and the second end 11b of the first movable member 11 is on the left side of the fulcrum 10a. The cross-section of the first movable member 11 is substantially U-shaped and is bent at a bending point 11c separated by a certain distance from the second end 11b. The first movable member 11 is connected to the upper end of the spring 12 in the vicinity of the first end 11a. The spring 12 biases the first end 11a of the first movable member 11 downward in the figure, whereby the second end 11b on the opposite side of the first movable member 11 pivotally supported by the fulcrum 10a is biased upward in the figure.

[0013] The second movable member (connecting member) 13 is a member pivotable around the pivot shaft 14. The second movable member 13 has an opening 13a at an end opposite to the pivot shaft 14, and the opening 13a houses the second end 11b of the first movable member 11. The second movable member 13 also has a protrusion 13b.

[0014] The rotating member (member to be restricted) 15 is a member (e.g., a cam) that can rotate around the rotation axis 15a. The rotating member 15 attempts to rotate in the clockwise direction (direction D1) in the figure, for example, by constantly applying the driving force of a motor (not shown). The rotating member 15 has a locking portion 15b on its outer periphery. The locking portion 15b engages with the protrusion 13b of the second movable member 13 in the first position in the example of FIG. 1A. In the state of FIG. 1A, the second end 11b of the first movable member 11 abuts against the inner surface of the opening 13a and biases the second movable member 13 in the counterclockwise turning direction in the figure. Therefore, the rotation of the rotating member 15 in the direction D1 is suppressed because the locking portion 15b is locked by the protrusion 13b.

[0015] In the example of FIG. 1B, when current is supplied to the solenoid 10, the first movable member 11 turns counterclockwise around the fulcrum 10a by the magnetic force of the solenoid 10, and the bending point 11c of the first movable member 11 moves downward (direction D2) in the figure. The bending point 11c abuts against the inner surface of the opening 13a and turns the second movable member 13 clockwise around the rotation axis 14. Then, the protrusion 13b of the second movable member 13 disengages from the rotating member 15 and retracts to the second position. That is, the second movable member 13 is displaceable between the first position and the second position. The solenoid 10 displaces the second movable member 13 from the first position to the second position by magnetic force. Further, the first movable member 11 is connected to the second movable member 13 and functions as a driving member that moves by the magnetic force of the solenoid 10 so as to move the second movable member 13. As a result, in the state of FIG. 1B, the rotation of the rotating member 15 is not suppressed, and the rotating member 15 rotates in the direction D1 under the driving force of the motor.

[0016] By directly or indirectly connecting the rotating member 15 described herein to some driven member, the mechanism including the rotating member 15 can be configured as a transmission mechanism that transmits the driving force from the motor to the driven member. This transmission mechanism can be switched (transitioned) between a transmission state in which the driving force is transmitted and a cutoff state in which the driving force is not transmitted by controlling the power supply to the solenoid 10. Further, the mechanism including the solenoid 10, the first movable member 11, and the second movable member 13 can be called a switching device 16 that switches between the transmission state and the cutoff state of the transmission mechanism. The switching device 16 may include a spring 12.

[0017] Here, as shown in FIG. 1A, in a state where the second movable member 13 and the rotating member 15 are engaged and the protrusion 13b of the second movable member 13 locks the locking portion 15b of the rotating member 15, a force such as a frictional force is generated between the second movable member 13 and the rotating member 15. Further, the rotating member 15 receives a force from the motor, and a mechanical stress due to the force with which the rotating member 15 tries to rotate may be applied between the protrusion 13b of the second movable member 13 and the locking portion 15b of the rotating member 15. Therefore, compared with the state where the rotating member 15 and the second movable member 13 are not engaged, a larger magnetic force of the solenoid 10 is required for the protrusion 13b of the second movable member 13 to disengage from the rotating member 15 (overcoming the force) by supplying power to the solenoid 10. On the other hand, once the engagement between the second movable member 13 and the rotating member 15 is released, the magnetic force of the solenoid 10 gives a large acceleration to the second movable member 13, and since the force that cancels the acceleration no longer exists, the second movable member 13 rotates at an excessive speed. When the second movable member 13 collides with another member, an unpleasant operating sound is generated for the user.

[0018] In the following sections, some embodiments for reducing such unpleasant operating sounds will be described in detail.

[0019] <2. First Embodiment> <2-1. Overall Configuration of the Device> FIG. 2 is a schematic diagram showing an example of the overall configuration of the image forming apparatus 100 according to the first embodiment. In the present embodiment, the image forming apparatus 100 is a printer that forms an image on a sheet by an electrophotographic method. However, the technology according to the present disclosure is also applicable to other types of image forming apparatuses such as copiers, facsimiles, and multifunction devices. Further, the technology according to the present disclosure is also applicable to image forming apparatuses that operate by other image forming methods such as an inkjet method.

[0020] The cassette 20 of the image forming apparatus 100 accommodates a stack of sheets. The feed roller 21 picks up the sheet P from the stack of sheets in the cassette 20 and feeds the sheet P to the conveyance path 40. The separation roller pair 22 separates a single sheet P from the remaining sheets to prevent double feeding of the sheets and conveys the sheet P along the conveyance path 40. The leading edge of the sheet P that has passed through the registration roller pair 23 is detected by the sheet sensor 41.

[0021] The process cartridge 30 is a detachable unit including a charging roller 31, a photosensitive drum 32, a developing roller 35, and a toner accommodating portion (not shown) with respect to the image forming apparatus 100. The process cartridge 30 may be regarded as an image forming means for forming an image on a sheet. The process cartridge 30 starts executing the image forming process based on the timing when the leading edge of the sheet P is detected by the sheet sensor 41. First, the charging roller 31 uniformly charges the surface of the photosensitive drum 32 that rotates clockwise in the figure. The exposure device 33 emits laser light according to the input image data of the print job. The laser mirror 34 reflects the laser light from the exposure device 33 and exposes the surface of the photosensitive drum 32 to the laser light. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 32. The developing roller 35 supplies toner to the photosensitive drum 32 to develop the electrostatic latent image on the surface of the photosensitive drum 32 and form a toner image. The photosensitive drum 32 further rotates while carrying the toner image and transfers the toner image to the sheet P that has reached the transfer position in cooperation with the transfer roller 36.

[0022] The fixing device 38 fixes the toner image on the sheet P by pressing and heating the sheet P that has passed through the transfer position. In the case of single-sided printing mode, the sheet P is discharged to the discharge tray 29 by the discharge roller pair 25. In the case of double-sided printing mode, the sheet P is sent into the reverse path 43 by a flapper (not shown). The conveyance direction of the sheet P is reversed based on the timing when the sheet sensor 42 detects the trailing edge of the sheet P. The reverse roller pair 26 sends the sheet P into the double-sided conveyance path 44. The sheet sensor 45 detects the sheet P that has entered the double-sided conveyance path 44. In the double-sided conveyance path 44, a double-sided conveyance roller pair 24 is disposed. The double-sided conveyance roller pair 24 conveys the sheet in the double-sided printing mode and feeds the sheet P from the double-sided conveyance path 44 to the conveyance path 40 in a state where the front and back sides are reversed. The double-sided conveyance roller pair 24 does not convey the sheet in the single-sided printing mode. The photosensitive drum 32 cooperates with the transfer roller 36 to transfer the toner image for the back side to the sheet P that has reached the transfer position again. Further, the sheet P that has completed double-sided printing after passing through the fixing device 38 is discharged to the discharge tray 29 by the discharge roller pair 25.

[0023] Each roller included in the configuration of the above-described image forming apparatus 100 is a driven member that operates by receiving the driving force of a motor. As will be described later, the image forming apparatus 100 includes a transmission mechanism that transmits the driving force of the motor to at least one driven member. The state of the transmission mechanism can be switched between a transmission state in which the driving force is transmitted to the driven member and a blocking state in which the driving force is not transmitted to the driven member. The switching of the state of the transmission mechanism is performed by controlling the magnetic force of a solenoid.

[0024] For example, the duplex conveyance roller pair 24 is mechanically connected to a motor via a transmission mechanism 140 (see FIGS. 3 and 4) described later. The transmission mechanism 140 is maintained in a cutoff state by constantly supplying current to a solenoid. When the timing to return the sheet P to the conveyance path 40 arrives in the duplex printing mode, the supply of current to the solenoid is interrupted, and the state of the transmission mechanism 140 transitions to a transmission state. As a result, the duplex conveyance roller pair 24 starts rotating, and the sheet P is fed from the duplex conveyance path 44 to the conveyance path 40. When the sheet sensor 45 detects the trailing edge of the sheet P, the supply of current to the solenoid is resumed, the state of the transmission mechanism 140 transitions to the cutoff state, and the duplex conveyance roller pair 24 stops rotating. The timing at which the duplex conveyance roller pair 24 feeds the sheet P to the conveyance path 40 can be determined, for example, so as to ensure a sufficient interval from a subsequent sheet. Naturally, the other rollers described with reference to FIG. 1 can also receive a driving force from the motor via the same transmission mechanism 140 or another transmission mechanism.

[0025] <2-2. Configuration of Control Function> FIG. 3 is a block diagram showing an example of the configuration of the control function of the image forming apparatus 100. The controller 110 shown in FIG. 3 is a drive control unit that controls the driving of various members of the image forming apparatus 100. For example, the controller 110 may include a general-purpose processing circuit such as a microprocessor or a microcontroller. Further, the controller 110 may include a dedicated processing circuit such as an ASIC or an FPGA. The control functions described below may be realized by any combination of software, firmware, and hardware. Referring to FIG. 3, the controller 110 includes an image forming control unit 120, a storage unit 125, and a conveyance control unit 130.

[0026] The image formation control unit 120 is a control means connected to a booster circuit 121, an exposure control circuit 122, and a fixing control circuit 123. The booster circuit 121 boosts the voltage of a power supply (not shown) and outputs high voltages for charging the photosensitive drum 32, developing an electrostatic latent image, and transferring a toner image to the charging roller 31, the developing roller 35, and the transfer roller 36, respectively. The exposure control circuit 122 controls the on / off of the laser light emitted from the exposure device 33 and the scanning of the laser light on the surface of the photosensitive drum 32 by the laser mirror 34. The fixing control circuit 123 controls the pressurization and heating of the sheet P by the fixing device 38. The fixing control circuit 123 may be connected to a thermistor (not shown) that detects the temperature of the heater of the fixing device 38.

[0027] The storage unit 125 is a storage means including an arbitrary combination of a random access memory (RAM), a read-only memory (ROM), and a hard disk drive (HDD). The RAM is an example of a temporary computer-readable storage medium. The ROM and the hard disk are examples of non-temporary computer-readable storage media. The storage unit 125 stores one or more control programs and various data (for example, setting data and image data).

[0028] The controller 110, more specifically, the conveyance control unit 130, is a control means connected to the sensor group 41, 42, ..., the direct current (DC) generation circuit 131, the motor 132, the feed clutch 133, and the transmission mechanism 140. The DC generation circuit 131 generates a low-voltage DC power source that serves as a supply source for direct current to several actuators such as a solenoid described later. The motor 132 generates a driving force for driving a plurality of driven members included in the image forming apparatus 100. The feed clutch 133 transmits the driving force from the motor 132 to the feed roller 21 or cuts off the transmission of the driving force to the feed roller 21. In the first state, the transmission mechanism 140 transmits the driving force from the motor 132 to the duplex conveyance roller pair 24, and in the second state, cuts off the transmission of the driving force to the duplex conveyance roller pair 24. As will be described in the next section, the state of the transmission mechanism 140 transitions according to the position of a movable member displaceable by the magnetic force of a solenoid. Note that the feed clutch 133 may also have the same configuration as the transmission mechanism 140.

[0029] <2-3. Configuration Example of Transmission Mechanism> FIG. 4 is a schematic diagram for explaining an example of the configuration of the transmission mechanism 140 and the switching device 160. In the example of FIG. 4, the transmission mechanism 140 includes a planetary gear mechanism 150. The transmission mechanism 140 may include a first gear 24a and a second gear 24b. The switching device 160 includes a solenoid 141, a first movable member 143, and a second movable member 145. The switching device 160 may include a spring 142. FIG. 4 shows a state in which the solenoid 141 is not powered. The transmission mechanism 140 and the switching device 160 shown in FIG. 4 may have the same configuration as the transmission mechanism and the switching device 16 shown in FIGS. 1A and 1B.

[0030] The first movable member (drive member) 143 is a plate-like member pivotally supported by the housing of the solenoid 141 and is rotatable. The first movable member 143 corresponds to the first movable member 11 in FIGS. 1A and 1B. The solenoid 141 corresponds to the solenoid 10 in FIGS. 1A and 1B. The first movable member 143 is connected to the upper end of the spring 142 near one end. The spring 142 biases the one end of the first movable member 143 downward in the drawing. Thereby, the other end of the first movable member 143 is biased upward in the drawing. The second movable member 145 is a member rotatable around the pivot shaft 144. The second movable member (movable member) 145 corresponds to the second movable member 13 in FIGS. 1A and 1B. The second movable member 145 has an opening 145a at the end opposite to the pivot shaft 144. By the opening 145a accommodating the other end of the first movable member 143, the first movable member 143 and the second movable member 145 are connected to each other in a form that allows both to rotate in conjunction with each other. In the present embodiment, as will be described below, when the first movable member 143 moves by the magnetic force of the solenoid 141, the second movable member 145 is displaced between the first position and the second position. The second movable member 145 has a protrusion 145b. The switching device 160 can be said to have a stopper portion including the first movable member 143 and the second movable member 145. The state where the second movable member 145 is in the first position and engaged with the cam 151 can be called the restricted state of the stopper portion. The state where the second movable member 145 is in the second position and disengaged from the cam 151 can be called the released state of the stopper portion. That is, the stopper portion can take a restricted state (engaged state) of engaging with the cam 151 and a released state (disengaged state) of disengaging from the cam 151. By changing the supply of current to the solenoid 141, the restricted state and the released state of the stopper portion are switched.

[0031] The planetary gear mechanism 150 typically includes a sun gear, planetary gears, a planetary carrier, and an internal gear, but only a part of its configuration is schematically shown in FIG. 4.

[0032] In this embodiment, the cam 151 (regulated member) is connected to the sun gear of the planetary gear mechanism 150. The cam 151 corresponds to the rotating member 15 in FIGS. 1A and 1B. The cam 151 has a locking portion 151b on its outer periphery. The locking portion 151b engages with the protrusion 145b of the second movable member 145 at the first position shown in FIG. 4. In this state, the rotation of the sun gear is suppressed. The output gear 152 is connected to the planetary carrier of the planetary gear mechanism 150. The internal gear of the planetary gear mechanism 150 receives the driving force of the motor 132 and constantly rotates counterclockwise in the figure. When the rotation of the sun gear is suppressed, the planetary gears of the planetary gear mechanism 150 revolve counterclockwise around the sun gear in conjunction with the rotation of the internal gear, and rotate the planetary carrier together with the output gear 152 counterclockwise around the rotation axis. The output gear 152 engages with the first gear 24a of the duplex conveyance roller pair 24, and the first gear 24a engages with the second gear 24b. When the output gear 152 rotates, the first gear 24a and the second gear 24b rotate in conjunction (but in opposite directions to each other), and the duplex conveyance roller pair 24 coaxial with the first gear 24a and the second gear 24b rotates. At this time, when the sheet P reaches the duplex conveyance roller pair 24, the sheet P is conveyed from left to right in the figure by the rotation of the duplex conveyance roller pair 24.

[0033] On one hand, when current is supplied to the solenoid 141, the first movable member 143 rotates counterclockwise by the magnetic force of the solenoid 141, and the left end of the first movable member 143 pushes down the second movable member 145 within the opening 145a, causing the first movable member 143 to rotate clockwise. Then, by locking the locking portion 151b of the cam 151 at the first position, the protrusion 145b of the second movable member 145 that had been suppressing the rotation of the sun gear disengages from the cam 151 and displaces to the second position. In this state, the sun gear and the cam 151 become rotatable. When the rotation of the sun gear is not suppressed (when the sun gear is not under load), the planetary gears rotate on their own axes without revolving around the sun gear (and the sun gear rotates idly in conjunction). Therefore, since the planetary carrier does not rotate, the output gear 152, the first gear 24a, and the second gear 24b also do not rotate, and the transmission of the driving force from the motor 132 to the duplex conveyance roller pair 24 is blocked. Note that the configuration of the planetary gear mechanism 150 is not limited to this configuration. As long as one of the three components, namely the sun gear, the planetary gear, and the planetary carrier, is connected to the cam 151, one of the remaining two is driven by the motor 132, and the last one is connected to the output gear 152.

[0034] When the supply of current to the solenoid 141 is stopped again, the first movable member 143 rotates clockwise by the elastic force of the spring 142, causing the second movable member 145 to rotate counterclockwise around the pivot axis 144. Then, the protrusion 145b of the second movable member 145 returns from the second position to the first position and locks the locking portion 151b of the cam 151. Thereby, the transmission of the driving force from the motor 132 to the duplex conveyance roller pair 24 is resumed, and the duplex conveyance roller pair 24 starts to rotate.

[0035] Here, an example in which the transmission mechanism transmits the driving force of the motor to the driven member in the first state where the locking portion of the transmission mechanism is engaged with the movable member and the second state where it is not engaged with the movable member has been described. The driven member can be, for example, a roller involved in the conveyance of the sheet. However, the technology according to the present disclosure is not limited to such an example. Conversely to the above-described example, the transmission mechanism may not transmit the driving force of the motor to the driven member in the first state and may transmit the driving force of the motor to the driven member in the second state. For example, by adopting a configuration in which a movable member biased to the first position locks a locking portion of a rotating body that can rotate in conjunction with the output gear, the rotation of the output gear can be suppressed in the first state to block the transmission of the driving force of the motor to the driven member.

[0036] Note that several members interlocking with each other may be interposed between the movable member directly acted on by the magnetic force of the solenoid and the movable member engaged with the regulated member. Also, the movable member itself directly acted on by the magnetic force of the solenoid may be engaged with the regulated member. For example, a protrusion engaged with the locking portion 151b of the cam 151 may be provided at one end of the first movable member 143 described with reference to FIG. 4.

[0037] <2-4. Power Supply Control of Solenoid> In the transmission mechanism 140 described in the previous item, the driving force of the motor 132 is applied in both the first state where the second movable member 145 is in the first position and the second state where the second movable member 145 is in the second position. The conveyance control unit 130 is configured to control the supply of current to the solenoid 141. For example, when the conveyance control unit 130 attempts to cut off the transmission of the driving force to the double-sided conveyance roller pair 24, it supplies current from the DC generation circuit 131 to the solenoid 141, thereby displacing the second movable member 145 from the first position to the second position. At this time, the conveyance control unit 130 changes the supply amount of current to the solenoid 141 over time in order to reduce the turning speed of the second movable member 145 after the second movable member 145 has disengaged from the planetary gear mechanism 150. Here, although not limited, the change in the supply amount of current is assumed to be realized by a pulse modulation method (for example, pulse amplitude modulation or pulse width modulation). That is, the conveyance control unit 130 changes the duty ratio of the power supply to the solenoid 141 to increase or decrease the magnetic force of the solenoid 141, thereby controlling the movement of the movable member.

[0038] FIG. 5 shows a graph representing an example of the change over time of the duty ratio of the power supply to the solenoid 141. The horizontal axis of the graph G1 in FIG. 5 represents the passage of time, and the vertical axis represents the duty ratio of the power supply to the solenoid 141 as a percentage.

[0039] Time T0 is the timing at which power supply to the solenoid 141 starts. In the first period from time T0 to time T1, the conveyance control unit 130 causes the DC generation circuit 131 to supply current to the solenoid 141 at the first duty ratio R1. Next, the conveyance control unit 130 causes the DC generation circuit 131 to supply current to the solenoid 141 at a second duty ratio R2 that is lower than the first duty ratio R1 in the second period after the first period. The second period continues until power supply from the DC generation circuit 131 to the solenoid 141 is stopped for restarting the transmission of the driving force to the double-sided conveyance roller pair 24. During the first period, the engagement between the second movable member 145 and the cam 151 is released, and the protrusion 145b of the second movable member 145 disengages from the locking portion 151b. The first period ends before the second movable member reaches the second position, and the second period starts after the end of the first period and before the second movable member reaches the second position. In other words, the length of the first period is shorter than the time it takes for the second movable member 145 to move from the first position to the second position. That is, current is supplied to the solenoid 141 at the first duty ratio R1 so that the second movable member 145 starts to be displaced from the first position toward the second position. Then, after the engagement between the second movable member 145 and the cam 151 is released and before the second movable member 145 reaches the second position, current is supplied to the solenoid 141 at the second duty ratio R2.

[0040] The first duty ratio R1 corresponds to the strength of the magnetic force of the solenoid 141 sufficient to overcome the driving force of the motor 132 and disengage the protrusion 145b of the second movable member 145 from the locking portion 151b. The first duty ratio R1 can be determined in advance in consideration of the load of the cam 151 depending on the driving force of the motor 132, the friction of the engaging surface of the locking portion 151b, mechanical and electrical variations, the characteristics of the solenoid 141, and the influence of temperature rise. The length of the first period can be determined in advance to be long enough for the protrusion 145b of the second movable member 145 to disengage from the locking portion 151b and shorter than the time length until the second movable member 145 (and the first movable member 143 that moves in conjunction therewith) collides with other members. That is, when a current is supplied to the solenoid 141 at the first duty ratio R1 in a state where the second movable member 145 and the cam 151 are engaged (a state where the protrusion 145b and the locking portion 151b are engaged), the second movable member 145 can start to be displaced from the first position toward the second position. In other words, in this case, the force received by the second movable member 145 is greater than the minimum force required for the second movable member 145 to move from the first position toward the second position. The second duty ratio R2 corresponds to the strength of the magnetic force of the solenoid 141 required to displace the second movable member 145 that has disengaged from the locking portion 151b toward the second position. That is, the second duty ratio R2 corresponds to the strength of the magnetic force of the solenoid 141 that can displace the second movable member 145 toward the second position in a state where the engagement between the locking portion 151b and the second movable member 145 is released. The second duty ratio R2 can be determined in advance to be a sufficiently low value within a range where the second movable member 145 can be surely displaced toward the second position against the elastic force of the spring 142 in consideration of mechanical and electrical variations. In the second period, since the load of the cam 151 is not applied to the second movable member 145, the second duty ratio R2 can be made significantly lower than the first duty ratio R1. Note that when a current is supplied to the solenoid 141 at the second duty ratio R2 in a state where the second movable member 145 and the cam 151 are engaged, the engagement between the second movable member 145 and the cam 151 is maintained.In other words, when a current is supplied to the solenoid 141 at the second duty ratio R2 with the second movable member 145 and the cam 151 engaged, the force received by the second movable member 145 due to the magnetic force of the solenoid 141 is smaller than the force required for the second movable member 145 to start displacing from the first position toward the second position. The storage unit 125 of the controller 110 stores in advance setting data indicating setting values such as the thus determined first duty ratio R1, second duty ratio R2, and the length of the first period.

[0041] FIG. 6A shows the positional relationship between the second movable member 145 and the cam 151 at the time T0 when power supply to the solenoid 141 is started. At the time T0, the second movable member 145 is in the first position, and the protrusion 145b of the second movable member 145 is engaged with the locking portion 151b of the cam 151.

[0042] FIG. 6B shows the positional relationship between the second movable member 145 and the cam 151 at the time T 11 immediately before the end of the first period. At the time T 11 the second movable member 145 is midway between the first position and the second position, and the protrusion 145b of the second movable member 145 has just detached from the locking portion 151b of the cam 151. At this point, the cam 151 is not locked by the second movable member 145 and is rotatable. A current is still supplied to the solenoid 141 at the first duty ratio R1, and the strong magnetic force of the solenoid 141 acts on the first movable member 143, but when the immediately subsequent time T1 arrives, the duty ratio is lowered to the second duty ratio R2.

[0043] FIG. 6C shows the positional relationship between the second movable member 145 and the cam 151 at the time T 12 in the middle of the second period. At the time T 12In this case, the second movable member 145 reaches the second position. On the other hand, the first movable member 143 is in contact with the housing of the solenoid 141 and its movement is restricted. The housing of the solenoid 141 functions as a restricting portion that restricts the movement of the first movable member 143. Note that the movement of the first movable member 143 may be restricted by a component different from the housing of the solenoid 141. The cam 151 rotates from time T 11 to time T 12 During the second period, since a current is supplied to the solenoid 141 at a second duty ratio R2 lower than the first duty ratio R1, the magnetic force of the solenoid 141, which is lower than that in the first period, acts on the first movable member 143. Before the second movable member 145 reaches the second position, the turning speeds of the first movable member 143 and the second movable member 145 decrease. The first movable member 143, for example, collides with the housing of the solenoid 141 and stops, and the second movable member 145 also stops.

[0044] <2-5. Example of processing flow> FIG. 7 is a flowchart showing an example of the flow of drive control processing that can be executed by the conveyance control unit 130 according to the present embodiment. The drive control processing shown in FIG. 7 can be realized, for example, by the processing circuit of the controller 110 executing a computer program stored in advance in the storage unit 125.

[0045] First, when the timing at which the driven member operating under the driving force of the motor 132 should stop arrives, in S111, the conveyance control unit 130 starts power supply to the solenoid 141 at the first duty ratio R1. In S113, the conveyance control unit 130 monitors the timer and waits for the elapse of the first period (also referred to as the high-duty period) while continuing the power supply at the first duty ratio R1. When the first period elapses, in S115, the conveyance control unit 130 lowers the duty ratio of the power supply to the solenoid 141 from the first duty ratio R1 to the second duty ratio R2.

[0046] <2-6. Summary of the first embodiment> In the first embodiment described in this section, in order to disengage the movable member that locks the transmission mechanism for transmitting the driving force of the motor from the transmission mechanism, the power supply to the solenoid is controlled so that the movable member is displaced from the first position to the second position by the magnetic force of the solenoid. Specifically, in the first period, current is supplied from the power supply to the solenoid at the first duty ratio, and in the second period after the first period, current is supplied from the power supply to the solenoid at the second duty ratio that is lower than the first duty ratio. Thereby, in the initial first period of the power supply control, a sufficiently high first duty ratio can be used to reliably disengage the movable member from the transmission mechanism to which the driving force of the motor is constantly applied. In addition, in the second period after the first period, the speed of the movable member that has become free from the load can be suppressed before reaching the second position, and the operating noise caused by the collision between the movable member and other members can be reduced. That is, it is possible to achieve both reliable detachment of the movable member and reduction of the operating noise that is unpleasant for the user.

[0047] In addition, although the configuration of the flapper type solenoid is mainly described in this embodiment, the technology according to the present disclosure is also applicable to other types of solenoids (for example, plunger type solenoids). Further, the driven member is not limited to the roller involved in the conveyance of the sheet. For example, the technology according to the present disclosure may be used for transmitting and blocking the driving force to members involved in the formation of an electrostatic latent image or a toner image, such as the charging roller 31, the photosensitive drum 32, the laser mirror 34, the developing roller 35, and the transfer roller 36.

[0048] In addition, the transition of the duty ratio shown in FIG. 5 is merely an example. For example, after the end of the first period, a multi-stage reduction of the duty ratio may be performed, such as further reducing the duty ratio from the second duty ratio to the third duty ratio.

[0049] <3. Second Embodiment> The smaller the duty ratio of the power supply to the solenoid described above, the more the speed of the movable member can be suppressed. However, in order to ensure the proper operation of the driven member against uncertain factors such as mechanical and electrical variations and the influence of temperature rise, a margin is required. The magnitude of the margin of the duty ratio and the magnitude of the operating noise caused by the collision between members are in a trade-off relationship. In the second embodiment described in this section, by incorporating repetitions of a high-duty period and a low-duty period into the control of the duty ratio over time, the margin of the duty ratio is reduced to further reduce the operating noise.

[0050] The overall configuration, the configuration of the control function, and the configuration of the transmission mechanism of the image forming apparatus 100 according to the second embodiment may be the same as those of the first embodiment. Also in the second embodiment, when the second movable member 145 at the first position suppresses the rotation of the cam 151 of the transmission mechanism 140, the driving force of the motor 132 is transmitted to the duplex conveyance roller pair 24. When the conveyance control unit 130 attempts to block the transmission of the driving force to the duplex conveyance roller pair 24, the conveyance control unit 130 supplies a current from the DC generation circuit 131 to the solenoid 141 to displace the second movable member 145 from the first position to the second position. Also in this embodiment, the conveyance control unit 130 controls the movement of the first movable member 143 and the second movable member 145 (interlocked with the first movable member 143) by changing the duty ratio of the power supply to the solenoid 141 over time.

[0051] <3-1. Power Supply Control of Solenoid> Specifically, in this embodiment, when the conveyance control unit 130 displaces the second movable member 145 from the first position to the second position, it repeatedly alternates a high-duty period and a low-duty period a plurality of times. Then, the conveyance control unit 130 increases the duty ratio at least in the high-duty period each time it repeats. The high-duty period and the low-duty period in the last repetition may be the same as the first period and the second period in the first embodiment, respectively. In the following description, the high-duty period and the low-duty period excluding the last repetition are referred to as the third period and the fourth period, respectively.

[0052] Assuming the number of repetitions is 1 for simplicity of explanation, the control sequence consists of the following four types of duty periods in time series. · Third period: Power is supplied to the solenoid at the third duty ratio R3. The third duty ratio R3 is lower than the first duty ratio R1 and higher than the second duty ratio R2. · Fourth period: Power is supplied to the solenoid at the fourth duty ratio R4. The fourth duty ratio R4 is lower than the third duty ratio R3. The fourth duty ratio R4 corresponds to the strength of the magnetic force of the solenoid for displacing the movable member detached from the transmission mechanism toward the second position. · First period: Power is supplied to the solenoid at the first duty ratio R1. The first duty ratio R1 corresponds to the strength of the magnetic force of the solenoid for detaching the movable member from the transmission mechanism against the driving force of the motor and includes a sufficient margin. · Second period: Power is supplied to the solenoid at the second duty ratio R2. The second duty ratio R2 corresponds to the strength of the magnetic force of the solenoid for displacing the movable member detached from the transmission mechanism toward the second position.

[0053] FIG. 8 shows a graph representing an example of the change over time of the duty ratio of power supply to the solenoid 141 according to the present embodiment. Similar to the graph G1 in FIG. 5, the horizontal axis of the graph G2 in FIG. 8 represents the passage of time, and the vertical axis represents the duty ratio of power supply to the solenoid 141 as a percentage. In the example of FIG. 8, the pair of the third duty period P3 3_i in which current is supplied to the solenoid 141 at the third duty ratio R i and the fourth duty period P4 4_i in which current is supplied to the solenoid 141 at the fourth duty ratio R i is repeated 4 times (i = 1, 2, 3, 4). Note that the number of repetitions of the third duty period P3 i and the fourth duty period P4 i may be less than 4 times or more than 4 times. The third duty ratio R i in the third duty period P3 3_i in the subsequent (i ≧ 2) times is the third duty ratio R of the immediately preceding third duty period P3i The third duty ratio R in 3_i is larger than. That is, R 3_i >R 3_i-1 is. The fourth duty period P4 in the second and subsequent times (i≧2) i The fourth duty ratio R in 4_i is the fourth duty ratio R in the immediately preceding fourth duty period P4 i is larger than. That is, R 4_i >R 4_i is. 4_i-1

[0054] Time T0 is the timing at which power supply to the solenoid 141 is started. In the first third period P31 from time T0 to time T 21 until, the conveyance control unit 130 supplies current to the solenoid 141 at the third duty ratio R 3_1 . Next, in the first fourth period P41 from time T 21 to time T 22 until, the conveyance control unit 130 supplies current to the solenoid 141 at a fourth duty ratio R 3_1 lower than the third duty ratio R 4_1 .

[0055] Next, in the second third period P32 from time T 22 to time T 23 until, the conveyance control unit 130 supplies current to the solenoid 141 at the third duty ratio R 3_2 . The third duty ratio R 3_2 is higher than the third duty ratio R 3_1 by the offset ΔR3. Next, in the second fourth period P42 from time T 23 to time T 24 until, the conveyance control unit 130 supplies current to the solenoid 141 at a fourth duty ratio R 3_2 lower than the third duty ratio R 4_2 . The fourth duty ratio R 4_2 is higher than the fourth duty ratio R 4_1 by the offset ΔR4.

[0056] ​Thereafter, in the third third period P33 and fourth period P43, as well as in the fourth third period P34 and fourth period P44, power is supplied to the solenoid 141 at an increasingly increased duty ratio. Next, power is supplied to the solenoid 141 at the first duty ratio R1 in the first period P1, and further power is supplied to the solenoid 141 at the second duty ratio R2 in the second period P2. The second period P2 continues until power supply to the solenoid 141 is stopped for resuming transmission of the driving force to the double-sided conveyance roller pair 24.

[0057] The four third periods P3 i The third duty ratio R 3_i in each of which is desirably corresponding to the strength of the magnetic force of the solenoid 141 with which the second movable member 145 may disengage from the transmission mechanism 140 (cam 151) overcoming the driving force of the motor 132. Whether or not the second movable member 145 disengages from the transmission mechanism 140 in each third period P3 i depends on uncertain factors such as mechanical and electrical variations and the influence of temperature rise. That is, in a situation where the second movable member 145 is likely to disengage from the transmission mechanism 140, the second movable member 145 may disengage from the transmission mechanism 140 in the first third period P31. On the other hand, in a situation where the second movable member 145 is unlikely to disengage from the transmission mechanism 140, the second movable member 145 does not disengage from the transmission mechanism 140 in the third period P3 i and the second movable member 145 may disengage from the transmission mechanism 140 in the first period P1. If the second movable member 145 disengages in the early high-duty period (third period), the second movable member 145 reaches the second position in the immediately following low-duty period (fourth period) and remains at the second position in the subsequent high-duty and low-duty periods. At the latest, the second movable member 145 disengages from the transmission mechanism 140 in the first period which is the last high-duty period and reaches the second position in the second period which is the last low-duty period.

[0058] The four fourth periods P4 i The fourth duty ratio R 4_iAll correspond to the strength of the magnetic force of the solenoid 141 necessary to displace the second movable member 145, which has detached from the transmission mechanism 140, toward the second position. The fourth duty ratio R 4_i Similar to the second duty ratio R2, it may be a sufficiently low value within the range where the second movable member 145 can be reliably displaced toward the second position against the elastic force of the spring 142.

[0059] The storage unit 125 of the controller 110 stores in advance setting data indicating setting values such as the duty ratio (e.g., the initial value R 3_1 , R 4_1、 and ΔR3, ΔR4) in each duty period, as well as the length of each duty period. In one embodiment, the offset ΔR3 can be determined according to the following formula: ΔR3 = (R1 - R 3_1 ) / k Similarly, the offset ΔR4 can be determined according to the following formula: ΔR4 = (R2 - R 4_1 ) / k Here, the numerical value k is an integer of 1 or more representing the number of repetitions of the third period and the fourth period.

[0060] In other embodiments, the offset for the increase in the duty ratio may differ for each individual duty period, and may be increased non-linearly with respect to the passage of time, for example. The storage unit 125 may store a table defining the increment (and period length) of the duty ratio for each duty period. Also, the duty ratio in the low duty period may be constant throughout all repetitions (i.e., R 4_i = R2).

[0061] <3-2. Example of the processing flow> FIG. 9 is a flowchart showing an example of the flow of drive control processing that can be executed by the conveyance control unit 130 according to the present embodiment. The drive control processing shown in FIG. 9 can be realized, for example, by a processing circuit of the controller 110 executing a computer program preliminarily stored in the storage unit 125.

[0062] First, in S211, the conveyance control unit 130 sets the third duty ratio R3 and the fourth duty ratio R4 to their respective initial values. Next, when the timing at which the driven member operating under the driving force of the motor 132 should stop arrives, in S213, the conveyance control unit 130 starts power supply to the solenoid 141 at the third duty ratio R3. In S215, the conveyance control unit 130 monitors the timer and waits for the elapse of the high duty period while continuing the power supply at the third duty ratio R3. When the high duty period elapses, in S217, the conveyance control unit 130 reduces the duty ratio of the power supply to the solenoid 141 from the third duty ratio R3 to the fourth duty ratio R4.

[0063] Subsequent processing branches in S219 depending on whether the current period is the last duty period. If the current period is not the last duty period, in S221, the conveyance control unit 130 continues to monitor the timer and waits for the elapse of the low duty period while continuing the power supply at the fourth duty ratio R4. When the low duty period elapses, in S223, the conveyance control unit 130 increases the third duty ratio R3 and the fourth duty ratio R4 by predetermined offsets ΔR3 and ΔR4, respectively. If the next high duty period is the last high duty period, the third duty ratio R3 becomes equal to the first duty ratio R1. Similarly, if the next low duty period is the last low duty period, the fourth duty ratio R4 becomes equal to the second duty ratio R2. Then, the processing returns to S213.

[0064] In S219, if the current period is the last duty period, the drive control processing in FIG. 9 ends. In this case, the low duty period is maintained until the transmission of the driving force to the driven member is restarted.

[0065] Note that the present embodiment is more beneficial in an embodiment where there are a plurality of solenoids for switching the states of the plurality of transmission mechanisms between a transmission state and a cutoff state. In such an embodiment, the conveyance control unit 130 may commonly control the supply of current to the plurality of solenoids by the series of control sequences described with reference to FIG. 8. In that case, while a certain solenoid displaces the corresponding movable member during a certain high-duty period, another solenoid may displace the corresponding movable member during another high-duty period. That is, each of the plurality of movable members disengages from the corresponding transmission mechanism at the timing when power feeding is performed at a duty ratio exceeding the value required for disengagement from the corresponding transmission mechanism. The timing may differ from one another for the plurality of movable members. As a result, while using the common control sequence of power feeding, the plurality of movable members can be displaced at suppressed speeds respectively, and their respective operating sounds can be effectively reduced.

[0066] <3-3. Modification Example> According to the above-described control of the repetitive duty ratio, while the acceleration when the movable member is disengaged from the transmission mechanism can be minimized to suppress the operating sound, the time until the movable member disengages from the transmission mechanism may become longer compared to the first embodiment. In particular, in a scenario where high-frequency operation and stop of the driven member are assumed, if it takes a long time to switch the state of the transmission mechanism that transmits the driving force, there is a risk that the switching becomes a bottleneck in productivity.

[0067] Therefore, in a certain modification example, the conveyance control unit 130 may selectively use one of the following two operation modes to control the power feeding from the DC generation circuit 131 to the solenoid 141. · First operation mode (repetitive drive control (see FIG. 8)): The power feeding to the solenoid 141 is performed by a control sequence covering the third period, the fourth period, the first period, and the second period. · Second operation mode (non-repetitive drive control (see FIG. 5)): The power feeding to the solenoid 141 is performed by a control sequence consisting of only the first period and the second period.

[0068] Typically, the first operation mode can be used in a scenario where frequent actuation and stop of the driven member are not assumed. For example, the first operation mode may include a single-sided printing mode in which the duplex conveyance roller pair 24 is not involved in the conveyance of the sheet. That is, when the single-sided printing mode is specified during the execution of a job, the driving of the duplex conveyance roller pair 24 is stopped while reducing the operating noise by repeating a high-duty period and a low-duty period with an increasing duty ratio. On the other hand, the second operation mode may include a duplex printing mode in which the duplex conveyance roller pair 24 is involved in the conveyance of the sheet. That is, when the duplex printing mode is specified, the operation time can be shortened by non-repetitive drive control when the duplex conveyance roller pair 24 is stopped multiple times during the execution of the job, and high productivity can be provided.

[0069] Generally, the more driven members (e.g., the duplex conveyance roller pair 24) that operate receiving the driving force of the motor, the greater the load on the motor. Therefore, in a situation where there is little margin in the torque of the motor 132 or a situation where temperature rise should be suppressed, it is desirable to stop the driven members that are not involved in the execution of the job. By switching the control sequence according to the assumed frequency of actuation / stop of the driven member as in this modification example, a good balance between suppression of the motor load or suppression of temperature rise and high productivity can be achieved.

[0070] <3-4. Summary of the Second Embodiment> In the second embodiment described in this section, when detaching the movable member from the transmission mechanism, the power supply control to the solenoid for displacing the movable member is performed by a control sequence consisting of an alternating repetition of a high-duty period and a low-duty period. And the duty ratio in the preceding high-duty period is set lower than the duty ratio in the subsequent high-duty period. Therefore, the displacement of the movable member from the first position to the second position can be triggered at a relatively low duty ratio without an excessive margin. Thereby, the displacement speed of the movable member can be suppressed, and the operating noise can be effectively reduced.

[0071] For example, since the resistance of a solenoid is temperature-dependent, when the temperature changes, the strength of the magnetic force generated when the solenoid is powered at the same duty ratio can also change. In order to ensure that the solenoid's magnetic force can displace the movable member regardless of any temperature change, the margin of the duty ratio must be correspondingly large. In the control sequence according to this embodiment, the displacement of the movable member is guaranteed by a sufficient margin during the last high-duty period (the first period), and the reduction of the operating noise is also achieved by a lower duty ratio during the early high-duty period (the third period). The same applies to the margins for allowing changes in other environmental conditions and variations during the manufacturing of the members.

[0072] <4. Third Embodiment> As described above, the duty ratio required to disengage the movable member from the transmission mechanism is affected by the mechanical and electrical variations of the product and can differ from product to product. Also, when the temperature of the solenoid changes, the strength of the magnetic force generated when the solenoid is powered at the same duty ratio can also change. In the third embodiment described in this section, instead of relying solely on the margin of the duty ratio to ensure the reliable displacement of the movable member against these factors causing variations in the required duty ratio, a mechanism for adaptively adjusting the duty ratio is incorporated.

[0073] The overall configuration of the image forming apparatus 100 according to the third embodiment, and the configuration of the transmission mechanism may be the same as those in the first and second embodiments. FIG. 10 is a block diagram showing an example of the configuration of the control functions of the image forming apparatus 100 according to the third embodiment. The controller 210 shown in FIG. 10 is a drive control unit that controls the driving of various members of the image forming apparatus 100. Similar to the controller 110 according to the first embodiment, the controller 210 may include one or both of a general-purpose processing circuit and a dedicated processing circuit. Referring to FIG. 10, the controller 210 includes an image forming control unit 120, a storage unit 225, and a conveyance control unit 230.

[0074] The storage unit 225 is a storage means including any combination of a RAM, a ROM, and an HDD. The storage unit 225 stores one or more control programs and various data. In particular, in the present embodiment, the storage unit 225 stores adjustment data 227. An example of the configuration of the adjustment data 227 will be described in detail later.

[0075] The controller 210, more specifically the conveyance control unit 230, is connected to the sensor group 41, 42,..., the DC generation circuit 131, the motor 132, the feed clutch 133, the transmission mechanism 140, and the temperature sensor 241. The temperature sensor 241 is a measuring means for measuring the temperature of the solenoid 141 (see FIG. 4). The temperature sensor 241 may be, for example, a thermistor or a thermocouple disposed near the solenoid 141.

[0076] The conveyance control unit 230 is configured to control the supply of current to the solenoid 141. When the conveyance control unit 230 attempts to cut off the transmission of the driving force from the motor 132 to the duplex conveyance roller pair 24, the conveyance control unit 230 supplies current from the DC generation circuit 131 to the solenoid 141, thereby displacing the second movable member 145 from the first position to the second position. At this time, the conveyance control unit 230 changes the supply amount of current to the solenoid 141 over time in order to reduce the turning speed of the second movable member 145 after detachment from the transmission mechanism 140. As a first example, the conveyance control unit 230 may lower the duty ratio of power supply to the solenoid 141 from the first duty ratio R1 to the second duty ratio R2 by non-repetitive driving control in the first embodiment. As a second example, the conveyance control unit 230 may repeatedly alternate a high-duty period and a low-duty period a plurality of times by repetitive driving control in the second embodiment. However, in any example, the conveyance control unit 230 adaptively determines at least one duty ratio based on the adjustment data 227 pre-stored in the storage unit 225.

[0077] The adjustment of the duty ratio in the present embodiment may include at least one of the following: · Correction for compensating for manufacturing variations ·Adjustment in accordance with the change in the required duty ratio due to temperature change

[0078] In a first example where non-repetitive drive control is performed, the conveyance control unit 230 can determine at least one of the first duty ratio R1 and the second duty ratio R2 based on the adjustment data 227. In a second example where repetitive drive control is performed, the conveyance control unit 230 can determine at least one of the first duty ratio R1, the second duty ratio R2, the third duty ratio R3, and the fourth duty ratio R4 based on the adjustment data 227. The adjustment in accordance with the change in the required duty ratio due to temperature change can be further performed based on the temperature of the solenoid 141 measured by the temperature sensor 241. That is, in the first example, the conveyance control unit 230 can adjust at least one of the first duty ratio R1 and the second duty ratio R2 based on the signal output from the temperature sensor 241. Also, in the second example, the conveyance control unit 230 can adjust at least one of the first duty ratio R1, the second duty ratio R2, the third duty ratio R3, and the fourth duty ratio R4 based on the signal output from the temperature sensor 241.

[0079] FIG. 11 shows an example of the configuration of adjustment data 227 assuming repetitive drive control. Referring to FIG. 11, the adjustment data 227 includes parameters of "reference value", "correction value", and "adjustment coefficient" for each of the first, second, third, and fourth duty ratios. The "reference value" indicates the value of the duty ratio that should be set when it is assumed that there is no variation in the product at a predetermined reference temperature. The reference temperature may be, for example, 20°C. Note that for the third and fourth duty ratios, the initial values before increment may be shown as the reference values. The "correction value" indicates the value that should be added to the reference value of the duty ratio in order to compensate for the influence of product variation. The correction values X1, X2, X3, and X4 for each duty ratio are determined, for example, based on the variation measured in the test after manufacturing the product, and can be written into the storage unit 225 (for example, non-volatile memory). The "adjustment coefficient" indicates a coefficient for adjustment in accordance with the change in the required duty ratio due to temperature change.

[0080] FIG. 12 shows a graph G3 representing the relationship between the temperature of the solenoid and the duty ratio required to disengage the second movable member 145 from the transmission mechanism 140. The graph G3 indicates the required duty ratio R when the temperature of the solenoid is 20°C, and the required duty ratio increases as the temperature rises. In a practically achievable temperature range, the change in the required duty ratio with respect to temperature change may be regarded as linear. Therefore, by setting the reference temperature to 20°C and adding the adjustment amount obtained by multiplying the temperature change from the reference temperature by the adjustment coefficient corresponding to the slope of the graph G3 to the reference value R ref (or the sum of the reference value and the correction value), a duty ratio suitable for the changed temperature can be derived. Alternatively, a more complex duty ratio adjustment model may be used according to the temperature characteristics of the solenoid 141. In the example of FIG. 11, different adjustment coefficients α1, α2, α3, and α4 are shown for the first, second, third, and fourth duty ratios, but a common adjustment coefficient may be used for adjusting a plurality of duty ratios. ref (or the sum of the reference value and the correction value), a duty ratio suitable for the changed temperature can be derived. Alternatively, a more complex duty ratio adjustment model may be used according to the temperature characteristics of the solenoid 141. In the example of FIG. 11, different adjustment coefficients α1, α2, α3, and α4 are shown for the first, second, third, and fourth duty ratios, but a common adjustment coefficient may be used for adjusting a plurality of duty ratios.

[0081] Note that the configuration of the adjustment data 227 shown in FIG. 11 is merely an example. The adjustment data 227 may further include correction values for the offsets ΔR3 and ΔR4 for iterative drive control, for example. Further, the storage unit 225 may store in advance a plurality of sets of adjustment data 227 respectively corresponding to a plurality of candidate values for attributes such as the type or number of turns of the solenoid, or the type of the motor. In that case, the conveyance control unit 230 may read out a data set corresponding to the attribute of the solenoid 141 or the motor 132 to be controlled from the storage unit 225 and use it for determining the duty ratio.

[0082] Further, instead of being directly measured by the temperature sensor 241, the temperature of the solenoid 141 may be estimated based on the history of power supply to the solenoid 141 and / or the ambient temperature.

[0083] In the third embodiment described in this section, the duty ratio in the power supply control to the solenoid for detaching the movable member from the transmission mechanism is adjusted in accordance with one or both of the product variation and the temperature change of the solenoid. Therefore, since the necessity of including an excessively large margin in the duty ratio is eliminated, the displacement speed of the movable member can be suppressed, or the time required until the displacement of the movable member is triggered can be shortened.

[0084] Note that a configuration including the transmission mechanism 140, the switching device 160, and the controller 110 or 210 (more specifically, the conveyance control unit 130 or 230) can be called a drive control device. That is, the image forming apparatus 100 includes a drive control device. The drive control device may include a power source that outputs a current supplied to the motor 132, the driven member, and the solenoid 141.

[0085] <5. Other Embodiments> The above-described embodiment can also be realized in a form of processing in which a program that realizes one or more functions is supplied to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

[0086] The disclosure of this specification includes at least the following drive control device and image forming apparatus. (Item 1) A movable member displaceable between a first position and a second position, A solenoid that displaces the movable member in the first position to the second position by magnetic force, Control means for controlling the supply of current from a power source to the solenoid, A transmission mechanism that transitions between a first state and a second state according to the position of the movable member, In one of the first state and the second state, transmits the driving force of the motor to the driven member, In the other of the first state and the second state, does not transmit the driving force of the motor to the driven member, The transmission mechanism, Comprising, When the solenoid displaces the movable member from the first position to the second position, the control means Supplies current to the solenoid at a first duty ratio so that the movable member is displaced from the first position toward the second position in a first period, In a second period that starts after the first period and before the movable member reaches the second position, supplies current to the solenoid at a second duty ratio lower than the first duty ratio. Drive control device. (Item 2) When the control means displaces the movable member from the first position to the second position, Supplies current to the solenoid at a third duty ratio that is lower than the first duty ratio and higher than the second duty ratio in a third period, In a fourth period after the third period, current is supplied to the solenoid at a fourth duty ratio lower than the third duty ratio, The first period is a period after the fourth period. The drive control device according to item 1. (Item 3) Before the first period, the control means repeats the third period and the fourth period a plurality of times, The third duty ratio is increased each time of repetition. The drive control device according to item 2. (Item 4) The control means In the first operation mode, current is supplied to the solenoid in a control sequence over the third period, the fourth period, the first period, and the second period, In a second operation mode different from the first operation mode, current is supplied to the solenoid in a control sequence consisting of only the first period and the second period. The drive control device according to item 2 or 3. (Item 5) The drive control device is used in an image forming apparatus that forms an image on a sheet, The first operation mode includes a single-sided printing mode, The second operation mode includes a double-sided printing mode, The driven member is a roller that does not convey the sheet in the single-sided printing mode and conveys the sheet in the double-sided printing mode. The drive control device according to item 4. (Item 6) The control means displaces a plurality of movable members respectively using a plurality of solenoids by a control sequence over the third period, the fourth period, the first period, and the second period. The drive control device according to any one of items 2 to 5. (Item 7) Further includes a sensor for detecting temperature, The control means determines at least one of the first duty ratio, the second duty ratio, the third duty ratio, and the fourth duty ratio based on a signal output from the sensor. The drive control device according to any one of items 2 to 6. (Item 8) The driving force of the motor is applied to the transmission mechanism in both the first state and the second state. The drive control device according to any one of items 1 to 7. (Item 9) The transmission mechanism has a locking portion locked by the movable member at the first position. In the first state, the locking portion and the movable member are engaged. In the second state, the locking portion and the movable member are not engaged. The drive control device according to any one of items 1 to 7. (Item 10) The second duty ratio corresponds to the strength of the magnetic force of the solenoid that can displace the movable member toward the second position in a state where the engagement between the locking portion and the movable member is released. The drive control device according to item 9. (Item 11) The drive control device further includes a drive member that is connected to the movable member and moves by the magnetic force of the solenoid so as to move the movable member. The drive control device according to item 9. (Item 12) The drive control device further includes a sensor that detects temperature. The control means determines at least one of the first duty ratio and the second duty ratio based on a signal output from the sensor. The drive control device according to any one of items 1 to 11. (Item 13) The drive control device further includes storage means for storing a correction value in advance. The control means adjusts at least one duty ratio based on the correction value stored in the storage means. The drive control device according to any one of Items 1 to 12. (Item 14) The drive control device according to any one of Items 1 to 13, image forming means for forming an image on the sheet, and an image forming apparatus comprising the same. (Item 15) The image forming apparatus according to Item 14, wherein the driven member is a roller that conveys the sheet.

[0087] The invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, the claims are appended to disclose the scope of the invention.

Description of Reference Numerals

[0088] 21, 22, 23, 24, 25, 26: Roller (driven member), 30: Process cartridge (image forming means), 100: Image forming apparatus, 125, 225: Storage unit (storage means), 130, 230: Conveyance control unit (control means), 131: DC generation circuit (power supply), 132: Motor, 133, 140: Transmission mechanism, 141: Solenoid, 143: First movable member, 145: Second movable member, 151b: Locking portion, 227: Adjustment data, 241: Temperature sensor (measurement means), P: Sheet, R1: First duty ratio, R2: Second duty ratio, R3: Third duty ratio, R4: Fourth duty ratio

Claims

1. A movable member displaceable between a first position and a second position, a solenoid that displaces the movable member in the first position to the second position by magnetic force, control means for controlling the supply of current from a power source to the solenoid, a transmission mechanism that transitions between a first state and a second state according to the position of the movable member, in one of the first state and the second state, transmits the driving force of the motor to the driven member, in the other of the first state and the second state, does not transmit the driving force of the motor to the driven member, the transmission mechanism, comprising, when the solenoid displaces the movable member from the first position to the second position, the control means supplies current to the solenoid at a third duty ratio that is lower than a first duty ratio and higher than a second duty ratio in a third period, in a fourth period after the third period, supplies current to the solenoid at a fourth duty ratio that is lower than the third duty ratio, in a first period after the fourth period, supplies current to the solenoid at the first duty ratio so that the movable member is displaced from the first position toward the second position, in a second period that starts after the first period and before the movable member reaches the second position, supplies current to the solenoid at the second duty ratio that is lower than the first duty ratio, a drive control device.

2. Before the first period, the control means repeatedly performs the third period and the fourth period a plurality of times, the third duty ratio is incremented each time of repetition, The drive control device according to claim 1.

3. The control means, in a first operation mode, supplies current to the solenoid in a control sequence over the third period, the fourth period, the first period, and the second period, in a second operation mode different from the first operation mode, supplies current to the solenoid in a control sequence consisting of only the first period and the second period, The drive control device according to claim 1.

4. The drive control device is used in an image forming apparatus that forms an image on a sheet, the first operation mode includes a single-sided printing mode, the second operation mode includes a double-sided printing mode, the driven member is a roller that does not convey the sheet in the single-sided printing mode and conveys the sheet in the double-sided printing mode, The drive control device according to claim 3.

5. The drive control device according to claim 1, wherein the control means displaces a plurality of movable members using a plurality of solenoids by a control sequence over the third period, the fourth period, the first period, and the second period.

6. Further comprising a sensor for detecting temperature, wherein the control means determines at least one of the first duty ratio, the second duty ratio, the third duty ratio, and the fourth duty ratio based on a signal output from the sensor. The drive control device according to claim 1.

7. The drive control device according to claim 1, wherein the driving force of the motor is applied to the transmission mechanism in both the first state and the second state.

8. The transmission mechanism has a locking portion locked by the movable member in the first position, in the first state, the locking portion and the movable member are engaged, in the second state, the locking portion and the movable member are not engaged. The drive control device according to claim 1.

9. The drive control device according to claim 8, wherein the second duty ratio corresponds to the strength of the magnetic force of the solenoid capable of displacing the movable member toward the second position in a state where the engagement between the locking portion and the movable member is released.

10. Further comprising a drive member connected to the movable member and moved by the magnetic force of the solenoid so as to move the movable member. The drive control device according to claim 8.

11. Further comprising storage means for storing a correction value in advance, wherein the control means adjusts at least one duty ratio based on the correction value stored in the storage means. The drive control device according to claim 1.

12. An image forming apparatus comprising the drive control device according to any one of claims 1 to 11, and image forming means for forming an image on a sheet.

13. The image forming apparatus according to claim 12, wherein the driven member is a roller for conveying the sheet.

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