JP4978600B2 - Driving force transmission device and image recording apparatus having the same - Google Patents

Description

  The present invention relates to a driving force transmission device that transmits driving forces of two motors to a first driven body and a second driven body, and an image recording apparatus including the driving force transmission device.

  2. Description of the Related Art Conventionally, a so-called inkjet recording type image recording apparatus that records an image on a recording sheet by attaching ink droplets to the recording sheet is known. In this type of image recording apparatus, a carriage on which a recording head is mounted is supported so as to be movable in a direction perpendicular to the recording sheet conveyance direction. The carriage is moved at a predetermined speed by a driving force transmitted from a carriage driving motor (hereinafter referred to as “CR motor”). On the other hand, a recording sheet on which an image is recorded is conveyed below the carriage by a conveyance roller. The transport roller is rotated at a predetermined rotational speed by a driving force transmitted from a motor for driving the transport roller (hereinafter referred to as “LF motor”).

  FIG. 9 is a block diagram showing a schematic configuration of a conventional feedback control system applied to a conventional image recording apparatus. In FIG. 9, the flow of electrical signals is indicated by broken lines, and the flow through which the driving force is transmitted is indicated by thick solid lines. As shown in FIG. 9, in the control system, the LF motor 211 and the CR motor 221 are each controlled by an independent control system.

As shown in FIG. 9, the drive current _ILF is supplied from the motor driver 201 to the LF motor 211 so that the transport roller 213 has a predetermined target speed. The driving force of the LF motor 211 is transmitted to the transport roller 213 through the gear driving mechanism 212. As a result, the transport roller 213 rotates. The actual rotational speed of the transport roller 213 is measured by an optical sensor 215 such as a rotary encoder. The measured rotation speed is fed back to the motor driver 201. The motor driver 201 obtains a deviation between the fed back rotation speed and the target speed, and adjusts the value of the drive current I _LF so that the actual rotation speed approaches the target speed. The CR motor 221 is feedback controlled by the motor driver 202. Specifically, the drive current _ICR is supplied from the motor driver 202 to the CR motor 221 so that the carriage 223 has a predetermined target speed. The driving force of the CR motor 221 is transmitted to the carriage 223 via the belt driving mechanism 222. As a result, the carriage 223 moves. The actual moving speed of the carriage 223 is measured by an optical sensor 225 such as a linear encoder. The measured moving speed is fed back to the motor driver 202. The motor driver 202 calculates a deviation between the fed-back moving speed and the target speed, to approximate the actual moving speed to the target speed, adjusting the value of the driving current I _CR.

  In the conventional image recording apparatus described above, image recording is performed as follows. First, the conveying roller receives the driving force of the LF motor and conveys the recording sheet until the leading end of the recording area of the recording sheet reaches below the recording head. When the leading edge of the recording area reaches below the recording head, the LF motor is temporarily stopped and the recording paper is stopped. In this state, when the CR motor is driven, the carriage stopped at the standby position is moved. In this movement process, the recording head selectively ejects ink droplets from the nozzles while moving with the carriage. As a result, an image for one line is recorded on the recording paper. When the carriage reaches the standby position, the CR motor is temporarily stopped. Thereafter, the LF motor is intermittently driven, and the conveyance roller conveys the recording paper by a predetermined width corresponding to one line. Thus, the recording paper is temporarily stopped every time it is conveyed by a predetermined width. During the pause, the carriage is moved, and an image is recorded line by line on the recording paper. By repeating this operation, a continuous image consisting of predetermined lines is recorded on the recording paper.

  In recent image recording apparatuses, the size of the recording head tends to increase as the number of nozzles of the recording head and the usable ink colors increase. Also, the carriage moving speed tends to increase to shorten the recording time. Increasing the size of the recording head and the speed of the carriage increase the load on the CR motor that drives the carriage. Therefore, it is necessary to adopt a higher output type CR motor than the conventional one. Also, when transporting thick recording paper such as glossy paper with glossy processing on the recording surface, or when rotating the transport roller at high speed in order to shorten the recording time, the LF for driving the transport roller The motor load increases. Therefore, it is necessary to adopt a high output type as the LF motor.

  By the way, as a device for transmitting the driving force of a motor to a predetermined driven body, a differential gear described in Patent Document 1, a reduction gear described in Patent Document 2, and the like are known. The former differential gear is configured such that two motors are connected via a belt and a pulley, and the driving force of these two motors is output from one output shaft. The latter speed reducer includes a plurality of input shafts to which a rotational force is input, a plurality of output shafts to which the rotational force is output, and a differential gear element interposed therebetween, and a plurality of rotational shafts. A plurality of reduced rotational outputs are obtained from the input.

JP-A-6-213301 JP-A-6-123337

  However, if a high-output type motor is employed, the size of the motor increases, leading to an increase in the size of the image recording apparatus itself. Further, by adopting a high output type motor, the cost is increased and the power consumption is increased. Therefore, in recent years when there is a strong demand for lower price, smaller size, and lower power consumption of image recording apparatuses, it is against the above requirement to employ a high output type motor for each of a plurality of driven bodies. It is not preferable. Note that the demand for lower price, smaller size, and lower power consumption is not limited to image recording devices. For example, in devices equipped with a large number of motors such as automobiles, industrial robots, portable terminals, and notebook computers. Is the same.

  Therefore, the present invention has been made in view of the above circumstances, and its object is to provide a driving force transmission device capable of obtaining a desired rotational output without increasing the size of the motor, and the same An object is to provide an image recording apparatus.

(1) The present invention is a driving force transmission device that transmits the driving force of the first motor and the second motor, whose rotational speeds are independently controlled by a predetermined control means, to the first driven body and the second driven body. is there. The driving force transmission device includes a first differential device and a second differential device. The first differential device includes a first input shaft coupled to the first rotation shaft of the first motor, a second input shaft coupled to the second rotation shaft of the second motor, and the first driven body. A first output shaft coupled to the first output shaft. The second differential device includes a third input shaft coupled to the first rotation shaft of the first motor, a fourth input shaft coupled to the second rotation shaft of the second motor, and the second driven body. A second output shaft connected to the second output shaft. In the driving force transmission device, when the first motor and the second motor are rotationally driven, the rotational speed of the first output shaft is a times the rotational speed of the first motor and the rotational speed of the second motor. The rotation speed of the second output shaft becomes c times the rotation speed of the first motor and d times the rotation speed of the second motor. A relationship of ad−bc ≠ 0 is established between each of the above a, b, c, and d. In other words, the driving force transmission device is configured such that ad-bc ≠ 0.

  Since it is configured in this way, in the driving force transmission device of the present invention, it is possible to obtain two primary independent rotation outputs from the first output shaft and the second output shaft. In other words, it is possible to independently control the rotation speeds of the first output shaft and the second output shaft, that is, the speed control of each of the first driven body and the second driven body. For example, when the conveyance roller as the first driven body and the carriage as the second driven body are driven almost alternately as in the image recording apparatus of the ink jet recording system, in other words, the conveyance roller and the carriage Are not driven at the same time, when the load applied to the carriage is maximum, the conveying roller is lightly loaded or unloaded. As described above, in a situation where the first motor and the second motor are driven in a state where one is high load and the other is low load, the driving force transmission device of the present invention includes the first output shaft and the second output shaft. The driving power (driving torque) of each of the first motor and the second motor can be distributed as follows by two primary independent rotational outputs of the output shafts. That is, the driving force of each of the first motor and the second motor is optimal for each driven body according to the load of each driven body, regardless of the operation state of each of the first driven body and the second driven body. Can be distributed. Thereby, it can utilize efficiently, without having the driving force of each of the 1st motor and the 2nd motor. As a result, a desired rotational output can be obtained without increasing the size of the motor.

  Further, as described above, regardless of the operating states of the first driven body and the second driven body, the driving forces of the first motor and the second motor depend on the load of each driven body. Since it is optimally distributed to each driving body, the driving force transmission device of the present invention is particularly effective at the time of start-up and low-speed driving that require a large torque.

  Further, in the conventional mechanism in which the transmission mechanism of the first driven body and the transmission mechanism of the second driven body are independent, each driven body has when the first driven body and the second driven body are decelerated. Although kinetic energy was converted to heat and wasted wastefully, in the driving force transmission device of the present invention, when one driven body decelerates, the kinetic energy of the driven body is reduced to the other. It is diverted as the driving force of the driving body. Therefore, energy can be used effectively in the driving force transmission device. In addition, the power consumption during deceleration can be reduced compared to the prior art.

(2) The driving force transmission device of the present invention further includes first transmission means, second transmission means, third transmission means, and fourth transmission means. The first transmission means is provided in a path from the first rotating shaft through the first input shaft to the first output shaft, and the transmission ratio is set to the “a”. The second transmission means is provided in a path from the second rotating shaft through the second input shaft to the first output shaft, and the transmission ratio is set to the “b”. The third transmission means is provided in a path from the first rotating shaft through the third input shaft to the second output shaft, and the transmission ratio is set to the “c”. The fourth transmission means is provided in a path from the second rotating shaft through the fourth input shaft to the second output shaft, and the transmission ratio is set to “d”. Here, the transmission ratio means a value obtained by dividing the rotational speed output from the transmission means by the rotational speed input to the transmission means. Therefore, for example, the transmission ratio of the first transmission means is a value obtained by dividing the rotational speed of the first output shaft by the rotational speed of the first motor (the rotational speed input to the first rotational shaft). Say. Needless to say, a relationship of ad−bc ≠ 0 is established between the transmission ratios.

  Thus, when the first motor and the second motor are driven to rotate, the rotational speed of the first output shaft is a times the rotational speed of the first motor and b times the rotational speed of the second motor. Therefore, the rotational speed of the second output shaft can be realized as a sum of c times the rotational speed of the first motor and d times the rotational speed of the second motor.

(3) The above a, the transmission ratio of the pathway leading to the first input shaft from the first rotation shaft of the first transmission means and a _1, a transmission ratio in the first differential unit and a ₂ Then, it is a ₁ a ₂ . Said b is the transmission ratio of the path to the second input shaft from the second rotation axis of the second transmission means and b _1, when the transmission ratio in the first differential device and b _2, b ₁ b ₂ . Said c is the transmission ratio of the path to the third input shaft from said first rotation axis of the third transmission means and c _1, when the transmission ratio in the second differential unit and c _2, c ₁ c ₂ . Further, the d is, the transmission ratio of the path to the fourth input shaft from the second rotation axis of the fourth transmission means and d _1, the transmission ratio in the second differential device When d ₂ , D ₁ d ₂ . In this case, a relationship of a ₁ a ₂ d ₁ d ₂ -b ₁ b ₂ c ₁ c ₂ ≠ 0 is established between the transmission ratios.

(4) The relationship of a = b and c = −d is established between each of a, b, c and d.

  Thereby, this invention can be used suitably with respect to the mechanism which drives a 1st to-be-driven body and a 2nd to-be-driven body substantially alternately.

(5) The driving force transmission device of the present invention further includes first rotation information acquisition means for acquiring rotation information of the first motor, and second rotation information acquisition means for acquiring rotation information of the second motor. . In this case, the control means feedback-controls the first motor and the second motor based on the acquisition results of the first rotation information acquisition means and the second rotation information acquisition means. The present invention can be preferably applied to such feedback control.

(6) Further, the driving force transmission device of the present invention has a first position information acquisition unit that acquires position information of the first driven body, and second position information that acquires position information of the second driven body. In the case where the acquisition means is provided, the control means feedback-controls the first motor and the second motor based on the acquisition results of the first position information acquisition means and the second position information acquisition means. Preferably there is. Also in this case, the present invention can be preferably applied.

(7) The present invention can also be understood as an ink jet recording type image recording apparatus including the above-described driving force transmission apparatus. In this case, the first driven body is a carriage that is reciprocated in a direction that intersects the conveyance direction of the recording medium. The second driven body is a conveyance roller that conveys a recording medium toward an image recording area by the recording head. In such an image recording apparatus, the driving force of the motor can be utilized most efficiently.

  According to the present invention, it is possible to independently control the rotational speed of each of the first output shaft and the second output shaft, that is, to control the speed of each of the first driven body and the second driven body, and In a situation where the first motor and the second motor are driven in a state where one is high load and the other is low load, the driving force (drive torque) of each of the first motor and the second motor is changed to the first target. Regardless of the operating states of the driving body and the second driven body, it is possible to optimally distribute according to the load of each driven body. Thereby, it can utilize efficiently, without having the driving force of each of the 1st motor and the 2nd motor. As a result, a desired rotational output can be obtained without increasing the size of the motor.

  Further, as described above, regardless of the operating states of the first driven body and the second driven body, the driving forces of the first motor and the second motor depend on the load of each driven body. Since it is optimally distributed to each driving body, the driving force transmission device of the present invention is particularly effective at the time of start-up and low-speed driving that require a large torque.

  Moreover, when one driven body decelerates, the kinetic energy which the driven body has is diverted as a driving force of the other driven body. Therefore, energy can be used effectively in the driving force transmission device. In addition, the power consumption during deceleration can be reduced compared to the prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. FIG. 1 is a perspective view showing the external configuration of the multifunction machine 1. FIG. 2 is a partially enlarged cross-sectional view showing the main configuration of the printer unit 2. FIG. 3 is a plan view showing the main configuration of the printer unit 2, and mainly shows the configuration on the back side of the apparatus from the approximate center of the printer unit 2. FIG. 4 is a model diagram schematically showing the differential transmission mechanism 110. FIG. 5 is a schematic diagram schematically showing a schematic configuration of the differential gear 111A. FIG. 6 is a block diagram schematically showing a schematic configuration of motor drive control by the motor driver 100. In FIG. 6, the flow of electrical signals is indicated by broken lines, and the flow through which driving force is transmitted is indicated by thick solid lines. FIG. 7 is a graph showing speed characteristics (speed change) of the carriage 38, the transport roller 87, the first motor 71, and the second motor 72. FIG. 8 is a block diagram schematically showing a schematic configuration of motor drive control which is a modification of the embodiment of the present invention. In FIG. 7, the speed change of the conveyance roller 87 is indicated by a broken line 61, and the speed change of the carriage 38 is indicated by a broken line 62. Further, a change in the rotation speed of the rotation shaft 74 of the first motor 71 is indicated by a solid line 63, and a change in the rotation speed of the rotation shaft 75 of the second motor 72 is indicated by a dotted line 64.

[Multifunction machine 1]
The multi-function device 1 is a multi-function device (MFP: Multi Function Product) that integrally includes a printer unit 2 and a scanner unit 3, and has a print function, a scan function, a copy function, a facsimile function, and the like. The printer unit 2 of the multifunction device 1 corresponds to the ink jet type image recording apparatus according to the present invention. Therefore, functions other than the print function are arbitrary, and for example, the image recording apparatus according to the present invention may be implemented as a printer having only a print function in which the scanner unit 3 is omitted.

  As shown in FIG. 1, the multifunction machine 1 is formed in a substantially rectangular parallelepiped. The lower part of the multifunction device 1 is the printer unit 2, and the upper part is the scanner unit 3.

  The printer unit 2 of the multifunction device 1 is mainly connected to an external information device such as a computer, and records images and documents on recording paper based on print data including image data and document data transmitted from the computer. To do. The printer unit 2 has an opening 9 formed in the front. The paper feed tray 20 and the paper discharge tray 21 are provided in two upper and lower stages inside the opening 9. When the recording paper stored in the paper feed tray 20 is fed into the printer unit 2 and a desired image is recorded on the recording paper, the recording paper on which the image has already been recorded is discharged to the paper discharge tray 21. Is done.

  The scanner unit 3 is configured as a so-called flat bed scanner. A document cover 30 as a top plate of the multifunction device 1 is provided on the upper portion of the scanner unit 3 so as to be freely opened and closed. A platen glass and an image sensor (not shown) are provided below the document cover 30. An image of a document placed on the platen glass is read by an image sensor. Since the scanner unit 3 is not relevant for realizing the present invention, detailed description of the scanner unit 3 is omitted here.

  As shown in FIG. 1, an operation panel 4 for operating the printer unit 2 and the scanner unit 3 is provided in the upper front portion of the multifunction machine 1. The operation panel 4 includes various operation buttons and a liquid crystal display unit. The multifunction device 1 operates based on an operation instruction from the operation panel 4. When the multifunction device 1 is connected to an external computer, the multifunction device 1 also operates based on an instruction transmitted from the computer via a printer driver or a scanner driver.

[Printer unit 2]
Hereinafter, the internal configuration of the multi-function device 1, particularly the configuration of the printer unit 2 will be described.

  As shown in FIG. 2, a paper feed tray 20 is provided on the bottom side of the multifunction machine 1. A paper feed roller 25 is provided above the paper feed tray 20. The paper feed roller 25 is pivotally supported at the tip of a paper feed arm 26 whose one end is pivotally supported on the base shaft 29. The paper feed arm 26 is provided with a gear drive mechanism 27 that transmits the rotational driving force input from the base shaft 29 to the paper feed roller 25. Inside the printer unit 2, a first motor 71 and a second motor 72 (see FIG. 6, examples of the first motor and the second motor of the present invention) are disposed. These motors 71 and 72 are configured to be able to be driven in the forward and reverse directions. The rotational driving force of each of the motors 71 and 72 is transmitted to the sheet feeding roller 25 via a differential transmission mechanism 110 (see FIG. 4), a base shaft 29, and a gear driving mechanism 27 described later. As a result, the paper feed roller 25 is driven to rotate. These motors 71 and 72 are not only the paper feed roller 25 but also a conveyance roller 87 (second driven body of the present invention, an example of the conveyance roller) and a carriage 38 (first of the present invention) as described later. It is also used as a drive source for driving a driven body and an example of a carriage.

  An inclined plate 22 is provided on the back side of the paper feed tray 20. When the paper supply roller 25 is rotated in a state where the paper supply roller 25 is pressed against the recording paper on the paper supply tray 20, the frictional force between the roller surface of the paper supply roller 25 and the recording paper causes the uppermost position. Recording paper is sent out to the inclined plate 22 side. The leading edge of the recording paper abuts on the inclined plate 22 and is guided upward. A sheet conveyance path 23 extends from the inclined plate 22. Specifically, the sheet conveyance path 23 is directed upward from the inclined plate 22 and is bent toward the front side of the multifunction device 1 and then extended from the back side to the front side of the multifunction device 1. It extends to the paper discharge tray 21 through the lower part of the image recording unit 24. Accordingly, the recording paper stored in the paper feed tray 20 is guided by the paper conveyance path 23 so as to make a U-turn from the lower side to the upper side, reaches the image recording unit 24, and after the image recording unit 24 performs image recording. The paper is discharged to the paper discharge tray 21.

  As shown in FIG. 2, an image recording unit 24 is disposed in the paper transport path 23. The image recording unit 24 includes an ink jet recording head 39 (an example of the recording head of the present invention) and a carriage 38 on which the recording head 39 is mounted. The carriage 38 is supported so as to be movable in a main scanning direction (direction perpendicular to the paper surface of FIG. 2) perpendicular to the recording sheet conveyance direction.

  The recording head 39 is disposed on the bottom surface of the carriage 38, and the nozzles of the recording head 39 are exposed on the lower surface of the carriage 38. Ink of each color is supplied to the recording head 39 from an ink cartridge (not shown) arranged inside the multifunction device 1. While the carriage 38 is moved back and forth, each color ink is selectively ejected from the nozzles of the recording head 39 as fine ink droplets. As a result, image recording is performed on the recording sheet conveyed on the platen 42.

  As shown in FIG. 3, a pair of guide rails 43 and 44 are arranged on the upper side of the sheet conveyance path 23. These guide rails 43 and 44 are opposed to each other with a predetermined distance in the recording paper conveyance direction (from the upper side to the lower side in FIG. 3), and are in the main scanning direction (FIG. 3) perpendicular to the recording paper conveyance direction. In the left-right direction). The guide rails 43 and 44 are provided in the housing of the printer unit 2 and constitute a part of a frame that supports each member constituting the printer unit 2. The carriage 38 is slidably mounted in the main scanning direction so as to straddle the guide rails 43 and 44.

  The guide rail 43 is disposed on the upstream side in the recording sheet conveyance direction. The guide rail 43 has a flat plate shape in which the length in the width direction (left and right direction in FIG. 3) of the sheet conveyance path 23 is longer than the reciprocating range of the carriage 38. Further, the guide rail 44 is disposed on the downstream side in the conveyance direction of the recording paper. The guide rail 44 has a flat plate shape in which the length in the width direction of the paper transport path 23 is substantially the same as that of the guide rail 43. The end of the carriage 38 on the upstream side in the transport direction is placed on the guide rail 43, and the end of the carriage 38 on the downstream side in the transport direction is placed on the guide rail 44, and the carriage 38 has the guide rails 43, 44. It is slid in the longitudinal direction.

  The edge 45 on the upstream side in the transport direction of the guide rail 44 is bent at a substantially right angle upward. The carriage 38 carried by the guide rails 43 and 44 has the edge 45 slidably held by a holding member such as a roller pair. Thus, the carriage 38 is positioned with respect to the recording paper conveyance direction and can slide in a direction orthogonal to the recording paper conveyance direction. That is, the carriage 38 is slidably supported on the guide rails 43 and 44 and reciprocates in a direction orthogonal to the conveyance direction of the recording paper with reference to the edge 45 of the guide rail 44.

  As shown in FIG. 3, a belt drive mechanism 46 is disposed on the upper surface of the guide rail 44. The belt drive mechanism 46 includes a drive pulley 47, a driven pulley 48, and an endless annular belt 49. In this embodiment, for convenience of explanation, it is assumed that the speed transmission ratio p of the belt drive mechanism 46, that is, the value obtained by dividing the output of the belt drive mechanism 46 by the input is set to “1”. Needless to say, the speed transmission ratio p can be appropriately changed to an arbitrary value according to the required operation and speed of the carriage 38.

  The driving pulley 47 and the driven pulley 48 are provided in the vicinity of both ends in the width direction of the sheet conveying path 23. An endless annular belt 49 is stretched between the driving pulley 47 and the driven pulley 48. The rotational driving force of the first motor 71 and the second motor 72 (see FIG. 6) is transmitted to the shaft of the drive pulley 47 via a differential transmission mechanism 110 (see FIG. 4) described later. Thereby, the drive pulley 47 is rotationally driven. The belt 49 moves circumferentially by the rotation of the drive pulley 47. In addition to the endless annular belt 49, a belt 49 that fixes both ends of the endless belt to the carriage 38 may be employed.

  The carriage 38 is connected to a belt 49 on the bottom surface side. Accordingly, the carriage 38 moves on the guide rails 43 and 44 with respect to the edge 45 based on the circumferential motion of the belt 49. The recording head 39 is mounted on such a carriage 38, and the recording head 39 is reciprocated with the width direction of the paper transport path 23 as the main scanning direction.

  As shown in FIG. 3, an encoder strip 50 is disposed on the guide rail 44. The encoder strip 50 is in the form of a strip made of a transparent resin. The encoder strip 50 has a pattern in which the light shielding portions and the light transmitting portions are arranged at an equal pitch. A pair of support ribs 33 and 34 are formed at both ends of the guide rail 44 in the width direction (movement direction of the carriage 38) so as to stand up from the upper surface thereof. Both ends of the encoder strip 50 are engaged with the supporting ribs 33 and 34, and are erected along the edge 45. The encoder strip 50 is tensioned by a spring or the like.

  On the upper surface of the carriage 38, at a position corresponding to the encoder strip 50, an optical sensor 35 (an example of the first position information acquisition means of the present invention) which is a transmission type sensor is provided. An encoder strip 50 is inserted between the light emitting element and the light receiving element of the optical sensor 35. The encoder strip 50 and the optical sensor 35 constitute a linear encoder for detecting the position of the carriage 38. In this embodiment, when the optical sensor 35 reads the pattern of the encoder strip 50, a detection signal indicating the position information of the carriage 38 is obtained. This detection signal is input to a motor driver 100 (an example of the control means of the present invention, see FIG. 6), which will be described later, and used for driving control of the first motor 71 and the second motor 72 (see FIG. 6).

  As shown in FIGS. 2 and 3, a platen 42 is disposed below the sheet conveyance path 23 so as to face the recording head 39. The platen 42 is disposed over a central portion of the moving range of the carriage 38 through which the recording paper passes. The width of the platen 42 is sufficiently larger than the maximum width of the recording paper that can be conveyed, and both ends of the recording paper always pass over the platen 42.

  As shown in FIG. 3, a maintenance mechanism 51 is disposed in a range where the recording paper does not pass, that is, outside the image recording area by the recording head 39. Specifically, the maintenance mechanism 51 is disposed at the right end of the platen 42 in FIG. The maintenance mechanism 51 prevents the ink in the nozzles of the recording head 39 from drying, and removes air bubbles and foreign matters from the nozzles. In the present embodiment, when image recording is not performed, the carriage 38 stands by on the maintenance mechanism 51 until an image recording instruction is input.

  As shown in FIG. 2, a pair of conveyance rollers 89 including a conveyance roller 87 and a pinch roller 88 are provided on the upstream side of the image recording unit 24. On the downstream side of the image recording unit 24, a pair of discharge rollers 92 having a discharge roller 90 and a spur 91 provided above the discharge roller 90 is provided. A gear drive mechanism 85 (see FIG. 6) composed of a plurality of gears is connected to the shaft of the transport roller 87. In this embodiment, for convenience of explanation, it is assumed that the rotational speed transmission ratio (gear ratio) q of the gear drive mechanism 85, that is, the value obtained by dividing the output of the gear drive mechanism 85 by the input is set to “1”. . Needless to say, the rotation speed transmission ratio q can be appropriately changed to any value according to the required operation and rotation speed of the conveying roller 87.

  The rotational driving force of the first motor 71 and the second motor 72 (see FIGS. 4 and 6) is transmitted to the shaft of the conveying roller 87 via the differential transmission mechanism 110 (see FIG. 4) and the gear driving mechanism 85 which will be described later. Is done. As a result, the transport roller 87 is rotated at a predetermined rotational speed, and the recording paper is transported through the paper transport path 23. The transport roller 87 and the paper discharge roller 90 are connected by a transmission mechanism such as a gear, and a driving force is transmitted from the transport roller 87 to the paper discharge roller 90 via the transmission mechanism. As a result, the transport roller 87 and the paper discharge roller 90 are driven synchronously. Note that while the recording paper is being intermittently conveyed by the conveyance roller 87, the paper supply roller 25 and the differential transmission mechanism 110 are disconnected, and the paper supply roller 25 is not driven to rotate.

  The recording sheet conveyed through the sheet conveyance path 23 is conveyed onto the platen 42 by the conveyance roller pair 89. The recorded recording paper on which an image is recorded on the platen 42 is conveyed to the paper discharge tray 21 by the discharge roller pair 92.

  An encoder disk 52 is provided on the rotation shaft of the transport roller 87. On the periphery of the encoder disk 52, a pattern in which light shielding portions and light transmitting portions are alternately arranged at an equal pitch is described. An optical sensor 83 (an example of second position information acquisition means of the present invention, see FIG. 6) is disposed at a position corresponding to the periphery of the encoder disk 52. The periphery of the encoder disk 52 is inserted between the light emitting element and the light receiving element of the optical sensor 83. The encoder disk 52 and the optical sensor 83 constitute a rotary encoder for detecting the rotational position of the transport roller 87. In the present embodiment, the pattern of the encoder disk 52 that rotates together with the transport roller 87 is read by the optical sensor 83. When the optical sensor 83 reads the pattern of the encoder disk 52, a detection signal indicating the rotational position information of the transport roller 87 is obtained. This detection signal is input to a motor driver 100 (see FIG. 6), which will be described later, and used for drive control of the first motor 71 and the second motor 72 (see FIGS. 4 and 6).

  In this embodiment, when an image recording instruction is input to the multifunction device 1 and the leading end of the recording area on the recording paper reaches below the recording head 39, the transport roller 87 is intermittently driven to rotate with a predetermined line feed width. The recording paper is intermittently conveyed with the same width. Specifically, according to the speed characteristic of the conveyance roller 87 shown in FIG. 7 (see the broken line 61), the rotation and stop of the conveyance roller 87 are repeated at predetermined intervals. Specifically, the transport roller 87 is stopped in the section t1, accelerated in the section t2, driven at a constant speed from the section t3 to the section t4, decelerated in the section t5, and stopped again in the section t6. In the section t7 to the section t11 and the subsequent sections, the same operations as those in the sections t1 to t6 are repeated.

  On the other hand, the carriage 38 starts to move from the standby position and reciprocates on the platen 42. Specifically, according to the speed characteristics of the carriage 38 shown in FIG. 7 (see the broken line 62), the movement in one direction and the movement in the opposite direction are repeated. More specifically, the carriage 38 is driven to decelerate from the section t2 to the section t3 from the state where it is driven at a constant speed in the section t1, and stops at the end of the section t3. Then, it is accelerated in the reverse direction in the section t4 and moved in the reverse direction from the section t4 to the section t5. And the constant speed drive of a reverse direction is performed in the area t6. And it is decelerated again from the section t7 to the section t8, and stops again at the end of the section t8. Then, it is accelerated in one direction in the section t9 and moved in the reverse direction from the section t9 to the section t10. And the constant speed drive of one direction is performed in the area t11. Thereafter, by repeating this operation, the carriage 38 reciprocates on the platen 42.

  In the present embodiment, as indicated by broken lines 61 and 62 in FIG. 7, the conveyance roller 87 is driven at a constant speed when the moving speed of the carriage 38 is decreasing or stopped. Further, the carriage 38 is driven at a constant speed when the rotation speed of the transport roller 87 is decreasing or stopped. That is, the transport roller 87 and the carriage 38 are driven almost alternately.

[Differential transmission mechanism 110]
The printer unit 2 includes a differential transmission mechanism 110 (an example of the driving force transmission device of the present invention) for transmitting the rotational driving force of each of the first motor 71 and the second motor 72 to the conveyance roller 87, the carriage 38, and the like. Is provided. As shown in FIG. 4, the differential transmission mechanism 110 includes a differential gear 111A (an example of the first differential device of the present invention) and a differential gear 111B (an example of the second differential device of the present invention). The first transmission unit 130 and the second transmission unit 135 are included.

  As shown in FIG. 5, the differential gear 111A includes an input shaft 114A (an example of a first input shaft of the present invention) and an input shaft 115A (an example of a second input shaft of the present invention). The input shaft 114A and the input shaft 115A are arranged coaxially. Further, the differential gear 111A has one output shaft 117A (an example of the first output shaft of the present invention). The output shaft 117A extends in a direction orthogonal to the input shafts 114A and 115A.

  The differential gear 111A has two pinion gears 119A and 120A arranged to face each other. These pinion gears 119A and 120A are bevel gears. The pinion gears 119A and 120A have the same number of teeth at the same pitch. An input shaft 114A is integrally connected to the pinion gear 119A. An input shaft 115A is integrally connected to the pinion gear 120A.

  A link gear 121A is provided on the input shaft 114A. The link gear 121A is arranged so that the rotational axis of the pinion gear 119A coincides. In the present embodiment, the link gear 121A is rotatably supported on the input shaft 114A. The link gear 121A is configured as a bevel gear. A pinion gear 122A is arranged so as to be able to mesh with the link gear 121A. The pinion gear 122A is a bevel gear and increases the rotational speed of the link gear 121A by a factor of two. That is, the rotational speed transmission ratio (gear ratio) from the link gear 121A to the pinion gear 122A is “2”. An output shaft 117A is integrally connected to the pinion gear 122A. In this embodiment, for convenience of explanation, the pinion gear 122A increases the rotational speed of the link gear 121A by a factor of 2, but the link gear 121A and the pinion gear 122A may have the same number of teeth. In short, the number of teeth and the pitch of the link gear 121A and the pinion gear 122A may be determined according to the rotational speed required as the rotational output of the output shaft 117A. In the following description, when rotation is transmitted through an odd number of gears when rotation is transmitted from "input gear that inputs rotation to the gear train" to "output gear that outputs rotation from the gear train", The output gear is defined to rotate in the same direction as the input gear, and the rotational speed transmission ratio from the input gear to the output gear is represented by a positive value. Similarly, when rotation is transmitted from the input gear to the output gear, the rotation is transmitted through an even number of gears, and when the rotation is transmitted through direct engagement of the input gear and the output gear (rotation is transmitted through 0 gears). In this case, it is defined that the input gear and the output gear rotate in opposite directions, and the rotational speed transmission ratio from the input gear to the output gear is represented by a negative value.

  An arm 123A is attached to one side surface of the link gear 121A. A shaft 124A extending in a direction orthogonal to the input shafts 114A and 115A is fixed to the arm 123A. The arm 123A, the shaft 124A, and the link gear 121A rotate integrally around the rotation axis of the link gear 121A.

Two pinion gears 125A and 126A are rotatably supported on the shaft 124A. The pinion gear 125A is engaged with the pinion gears 119A and 120A on one end side of the shaft 124A. The pinion gear 126A is meshed with the pinion gears 119A and 120A on the other end side of the shaft 124A. In terms of the mechanism, it is sufficient that either one of the pinion gear 125A or the pinion gear 126A is provided. However, in order to ensure equilibrium, the two pinion gears 125A and 126A are meshed with the pinion gears 119A and 120A. Note that the rotational speed transmission ratio between the pinion gears 119A and 120A and the pinion gear 125A needs to match the rotational speed transmission ratio between the pinion gears 119A and 120A and the pinion gear 126A, but the rotational speed transmission ratio itself. Does not affect the transmission ratio of the entire differential gear 111A, and may not be 1. If the shaft 124A is fixed and the pinion gear 125A is rotated, the pinion gear 119A and the pinion gear 120A have the same number of teeth at the same pitch, so the input shaft 114A and the input shaft 115A rotate in the opposite directions at the same rotational speed. It is clear to do. That is, it can be seen that the pinion gear 119A and the pinion gear 120A always rotate in the opposite direction with respect to the shaft 124A and the arm 123A. Well, here, the input shaft 114A rotates at a rotational speed _{V 1,} the input shaft 115A rotates at a rotation speed _{V 2} in the same direction as the input shaft 114A. When this motion is observed from an observer rotating around the input shaft 114A in the same direction as the input shaft 114A at a rotational speed (V ₁ + V ₂ ) / 2, the input shaft 114A is relatively relative to the observer. The rotation speed V ₁ − (V ₁ + V ₂ ) / 2 = (V ₁ −V ₂ ) / 2, and the input shaft 115A rotates relative to the observer at a rotation speed V ₂ − (V ₁ + V ₂ ) /. It is rotating at 2 = − (V ₁ −V ₂ ) / 2. Since the input shaft 114A and the input shaft 115A are rotating in the opposite directions with respect to the observer at the same rotation speed, the observer is rotating together with the shaft 124A and the arm 123A. Since this relationship is to hold in identically, when the input shaft 114A rotates at a rotational speed _{V 1,} the input shaft 115A rotates at a rotation speed _{V 2} in the same direction as the input shaft 114A, the shaft 124A and the arms 123A, The link gear 121A rotates at a rotation speed (V ₁ + V ₂ ) / 2. Therefore, the rotational speed transmission ratio from the pinion gear 119A to the link gear 121A is “½”, and the rotational speed transmission ratio from the pinion gear 120A to the link gear 121A is also “½”. That is, the sum of 1/2 of the rotation speed of the pinion gear 119A and 1/2 of the rotation speed of the pinion gear 120A appears in the rotation speed of the link gear 121A. Accordingly, when the rotational speed of the link gear 121A is considered separately for each rotational speed input from the input shafts 114A and 115A, the rotational speed transmission ratio at which the rotational speed of the pinion gear 119A is transmitted from the pinion gear 119A to the link gear 121A. Is “½”, and the rotational speed transmission ratio at which the rotational speed of the pinion gear 120A is transmitted from the pinion gear 120A to the link gear 121A is also “½”. Since the rotational speed transmission ratio as described above from the ring gear 121A to the pinion gear 122A is "2", the angular speed transmission ratio from the pinion gear 119A to the pinion gear 122A (corresponding to the transmission ratio a ₂ of the present invention) is "1" , and the angular speed transmission ratio from the pinion gear 120A to the pinion gear 122A (corresponding to the transmission ratio _{b 2} of the present invention) is also "1".

Therefore, in the differential gear 111A configured in this way, when the input shaft 114A and the input shaft 115A are rotated at a predetermined rotational speed, the output shaft 117A is rotated by the rotational speed of the input shaft 114A and the rotation of the input shaft 115A. The motor rotates at a rotation speed proportional to the value added to the speed. Specifically, since the pinion gear 119A, the pinion gear 120A, the ring gear 121A and the pinion gear 122A are configured as described above, for example, the input shaft 114A is rotated at a rotational speed _{V 1,} the input shaft 115A and the input shaft 114A When rotated in the same direction at the rotation speed V ₂ , the output shaft 117A rotates at the rotation speed (V ₁ + V ₂ ).

As shown in FIG. 4, the differential gear 111B includes an input shaft 114B (an example of the third input shaft of the present invention), an input shaft 115B (an example of the fourth input shaft of the present invention), and one output shaft. 117B (an example of the second output shaft of the present invention). The differential gear 111B has the same configuration as that of the differential gear 111A. The pinion gears 119B and 120B have the same shape as the pinion gears 119A and 120A, the arm 123B has the same shape as the arm 123A, and the same shape as the shaft 124A. The shaft 124B has pinion gears 125B and 126B having the same shape as the pinion gears 125A and 126A. Moreover, it has the link gear 121B of the same shape as the ring gear 121A, and the pinion gear 122B of the same shape as the pinion gear 122A. Therefore, the input / output characteristics of the differential gear 111A coincide with the input / output characteristics of the differential gear 111B. That is, the angular speed transmission ratio from the pinion gear 119B to the pinion gear 122B (corresponding to the transmission ratio _{c 2} of the present invention) is "1", the angular speed transmission ratio from the pinion gear 120B to the pinion gear 122B (transmission ratio _{d 2} of the present invention Is also “1”. Since each component of the differential gear 111B is the same as that of the differential gear 111A, detailed description thereof is omitted here.

  In the present embodiment, as shown in FIG. 4, the differential gear 111A and the differential gear 111B are arranged side by side. A carriage 38 is coupled to the output shaft 117A of the differential gear 111A via a belt drive mechanism 46 (transmission ratio p = 1) (see FIG. 6). On the other hand, a conveyance roller 87 is connected to the output shaft 117B of the differential gear 111B via a gear drive mechanism 85 (transmission ratio q = 1) (see FIG. 6).

[First transmission unit 130]
A first transmission unit 130 is provided on the input shaft 114A of the differential gear 111A and the input shaft 114B of the differential gear 111B. The first transmission unit 130 has three gears 131, 132, and 133. Each of these gears 131, 132, 133 is configured as a substantially disc-shaped spur gear. The gear 131 is integrally attached to the input shaft 114A. The gear 132 is integrally attached to the input shaft 114B. The gear 133 is meshed with both the gear 131 and the gear 132. A rotating shaft 74 (an example of the first rotating shaft of the present invention) of the first motor 71 is integrally connected to the gear 133. That is, the input shaft 114 </ b> A of the differential gear 111 </ b> A is connected to the rotating shaft 74 of the first motor 71 via the gear 131 and the gear 133 of the first transmission unit 130. Accordingly, the rotational driving force of the first motor 71 is transmitted to the input shaft 114 </ b> A through the gear 133 and the gear 131 sequentially. Such a transmission mechanism including the gear 131 and the gear 133 and the pinion gear 122A of the differential gear 111A described above corresponds to the first transmission means of the present invention.

  Further, the input shaft 114 </ b> B of the differential gear 111 </ b> B is connected to the rotation shaft 74 of the first motor 71 via the gear 132 and the gear 133 of the first transmission unit 130. Accordingly, the rotational driving force of the first motor 71 is transmitted to the input shaft 114B through the gear 133 and the gear 132 in this order. Such a transmission mechanism including the gear 132 and the gear 133 and the above-described differential gear 111B pinion gear 122B corresponds to the third transmission means of the present invention.

  As described above, since the rotation shaft 74 of the first motor 71 and the input shafts 114A and 114B are connected by the first transmission unit 130, the rotation direction of the first motor 71 and the input shafts 114A and 114B, respectively. Transmits the rotational driving force in the opposite direction. Therefore, for example, as shown in FIG. 4, when the first motor 71 is rotated in the direction of the arrow 53, the input shafts 114 </ b> A and 114 </ b> B are rotated in the direction of the arrow 54.

In the present embodiment, all the three gears 131, 132, 133 included in the first transmission unit 130 have the same configuration, and have the same number of teeth at the same pitch. Therefore, the rotation speed transmission ratio (gear ratio) from the rotation shaft 74 to the input shaft 114A through the gear 133 and the gear 131, that is, the rotation speed of the input shaft 114A is set to the rotation speed of the rotation shaft 74 (of the first motor 71). The value divided by (rotational speed) is “1”. Therefore, when the first motor 71 rotates at a certain rotation speed, the input shaft 114 </ b> A rotates at the same rotation speed as the first motor 71. However, since two gears (gear 133 and gear 131) are interposed between the rotating shaft 74 and the input shaft 114A, the input shaft 114A rotates in a direction opposite to the rotating direction of the first motor 71. become. Here, in the following description, in order to simplify the description, a negative sign “−” indicating that the rotation direction of the first motor 71 and the rotation direction of the input shaft 114A are different is attached to the rotation speed transmission ratio. In the case where the rotation direction is the same, no reference numeral is given. Therefore, in the following description, the rotation speed transmission ratio from the rotation shaft 74 through the gear 133 and the gear 131 to the input shaft 114A is represented as “−1”. Note that the angular speed transmission ratio may correspond to a transmission ratio a ₁ of the present invention.

Further, the rotation speed transmission ratio (gear ratio) from the rotation shaft 74 to the input shaft 114B through the gear 133 and the gear 132, that is, the rotation speed of the input shaft 114B is set to the rotation speed of the rotation shaft 74 (of the first motor 71). The value divided by (rotational speed) is also “1”. Therefore, when the first motor 71 rotates at a certain rotation speed, the input shaft 114 </ b> B rotates at the same rotation speed as the first motor 71. However, since two gears (gear 133 and gear 132) are interposed between the rotating shaft 74 and the input shaft 114B, the input shaft 114B rotates in a direction opposite to the rotating direction of the first motor 71. become. Therefore, in the following description, the rotation speed transmission ratio from the rotation shaft 74 through the gear 133 and the gear 132 to the input shaft 114B is represented as “−1”. Note that the angular speed transmission ratio may correspond to a transmission ratio c ₁ of the present invention.

[Second transmission unit 135]
A second transmission portion 135 is provided on the input shaft 115A of the differential gear 111A and the input shaft 115B of the differential gear 111B. The second transmission unit 135 has three gears 136, 137, and 138. These are configured as substantially disk-shaped spur gears. The gear 136 is integrally attached to the input shaft 115A. The gear 137 is integrally attached to the input shaft 115B. The gear 136 and the gear 137 are meshed with each other. The gear 138 is meshed with the gear 136. A rotating shaft 75 (an example of the second rotating shaft according to the present invention) of the second motor 72 is integrally connected to the gear 138. That is, the input shaft 115 </ b> A is connected to the rotation shaft 75 of the second motor 72 via the gears 136 and 138 of the second transmission unit 135. Therefore, the rotational driving force of the second motor 72 is transmitted to the input shaft 115A through the gears 138 and 136 in order. Such a transmission mechanism including the gears 136 and 138 and the pinion gear 122A of the differential gear 111A described above corresponds to the second transmission means of the present invention.

  Further, the input shaft 115 </ b> B of the differential gear 111 </ b> B is connected to the rotating shaft 75 of the second motor 72 via gears 137, 136 and 138 of the second transmission unit 135. Therefore, the rotational driving force of the second motor 72 is transmitted to the input shaft 115B through the gears 138, 136, and 137 sequentially. Such a transmission mechanism including the gears 136, 137, 138 and the pinion gear 122B of the differential gear 111B described above corresponds to the fourth transmission means of the present invention.

  As described above, since the rotation shaft 75 of the second motor 72 and the input shafts 115A and 115B are connected by the second transmission unit 135, the rotation direction of the second motor 72 is opposite to the input shaft 115A. A rotational driving force is transmitted, and a rotational driving force in the same direction as the rotational direction of the second motor 72 is transmitted to the input shaft 115B. Therefore, for example, as shown in FIG. 4, when the second motor 72 is rotated in the direction of the arrow 56, the input shaft 115A is in the direction of the arrow 55 opposite to the arrow 56 (the same direction as the input shafts 114A and 114B). ). On the other hand, the input shaft 115B is rotated in the direction of the arrow 55 that is the same as the rotation direction of the second motor 72 (the direction opposite to the input shafts 114A and 114B).

In the present embodiment, the three gears 136, 137, and 138 included in the second transmission unit 135 all have the same configuration, and have the same number of teeth at the same pitch. Therefore, the rotation speed transmission ratio (gear ratio) from the rotation shaft 75 to the input shaft 115A through the gear 138 and the gear 136, that is, the rotation speed of the input shaft 115A is set to the rotation speed of the rotation shaft 75 (of the second motor 72). The value divided by (rotational speed) is “1”. Therefore, when the second motor 72 rotates at a certain rotational speed, the input shaft 115 </ b> A rotates at the same rotational speed as the second motor 72. However, since two gears (gear 138 and gear 136) are interposed between the rotary shaft 75 and the input shaft 115A, the input shaft 115A rotates in a direction opposite to the rotation direction of the second motor 72. become. Here, in the following description, in order to simplify the description, a negative sign “−” indicating that the rotation direction of the second motor 72 and the rotation direction of the input shaft 115A are different is attached to the rotation speed transmission ratio. In the case where the rotation direction is the same, no reference numeral is given. Therefore, in the following description, the rotational speed transmission ratio from the rotating shaft 75 to the input shaft 115A through the gear 138 and the gear 136 is represented as “−1”. This rotational speed transmission ratio corresponds to the transmission ratio b ₁ of the present invention.

Further, the rotational speed transmission ratio (gear ratio) from the rotating shaft 75 to the input shaft 115B through the gear 138, the gear 136, and the gear 137 in sequence, that is, the rotational speed of the input shaft 115B is set to the rotational speed of the rotating shaft 75 (the first speed). The value divided by the rotational speed of the two motors 72 is also “1”. Therefore, when the second motor 72 rotates at a certain rotation speed, the input shaft 115B rotates at the same rotation speed as the second motor 72. Since three gears (gears 138, 136, and 137) are interposed between the rotary shaft 75 and the input shaft 115B, the input shaft 115B rotates in the same direction as the rotation direction of the second motor 72. Become. Therefore, in the following description, the rotational speed transmission ratio from the rotation shaft 75 to the input shaft 115B through the gear 138, the gear 136, and the gear 137 is represented as “1”. Note that the angular speed transmission ratio may correspond to a transmission ratio d ₁ of the present invention.

  In the present embodiment, as described above, the rotational speed transmission ratio from the link gear 121A to the pinion gear 122A is “2”, and the rotational speed transmission ratio from the rotational shaft 74 to the input shaft 114A is “−1”. If the rotational speed transmission ratio of the transmission mechanism from the rotary shaft 74 to the input shaft 114A, the inside of the differential gear 111A (pinion gear 122A, etc.) and the output shaft 117A is “a”, this rotational speed transmission ratio “a” is , “−1”. Since the rotational speed transmission ratio from the rotating shaft 75 to the input shaft 115A is “−1”, the rotating shaft 75 reaches the output shaft 117A via the input shaft 115A and the inside of the differential gear 111A (pinion gear 122A, etc.). If the rotational speed transmission ratio of the transmission mechanism is “b”, this speed transmission ratio “b” is “−1”.

  Further, since the rotation speed transmission ratio from the link gear 121B to the pinion gear 122B is “2” and the rotation speed transmission ratio from the rotation shaft 74 to the input shaft 114B is “−1”, the rotation shaft 74 to the input shaft 114B. If the rotational speed transmission ratio of the transmission mechanism that reaches the output shaft 117B through the inside of the differential gear 111B (such as the pinion gear 122B) is “c”, the speed transmission ratio “c” is “−1”. Further, since the rotational speed transmission ratio from the rotating shaft 75 to the input shaft 115B is “1”, transmission from the rotating shaft 75 to the output shaft 117B via the input shaft 115B and the inside of the differential gear 111B (pinion gear 122B, etc.). When the rotational speed transmission ratio of the mechanism is “d”, this rotational speed transmission ratio “d” is “1”.

In the thus configured differential transmission mechanism 110, as shown in FIG. 4, the rotation shaft 74 of the first motor 71 is rotated in the direction of the arrow 53 at the rotation speed X, and the rotation of the second motor 72 is performed. When the shaft 75 is rotated in the direction of the arrow 56 at the rotational speed Y, the rotational speed u of the output shaft 117A and the rotational speed v of the output shaft 117B are expressed by the following equations using the rotational speed transmission ratios a to d. It can be expressed as (1). In addition, the symbol A in Formula (1) represents the rotational speed transmission ratios a to d in a 2 × 2 matrix. This matrix A is detA = ad−bc = −2, and satisfies the condition of detA ≠ 0. Therefore, the matrix A has an inverse matrix A- ¹ .

[Motor driver 100]
The printer unit 2 is provided with a motor driver (hereinafter abbreviated as “driver”) 100 (see FIG. 6) as an example of a control unit. The driver 100 independently controls the rotational speeds of the first motor 71 and the second motor 72. The driver 100 mainly includes a target speed generation unit 103, a drive amount conversion unit 105, a drive amount conversion unit 106, a calculation unit 102, and a drive current conversion unit 104.

  The calculation unit 102 is configured as a microcomputer mainly including a CPU, a ROM, a RAM, and the like, for example.

  The ROM stores a program used for driving control of the first motor 71 and the second motor 72, a program used for analysis of detection signals output from the optical sensors 35 and 83, and the like.

  The RAM is used as a storage area for temporarily storing various data used when the CPU executes the program, or as a work area for performing arithmetic processing. For example, detection signals output from the optical sensors 35 and 83, position information obtained from the detection signals, and the like are stored in the RAM.

  The target speed generation unit 103 generates a target speed U of the carriage 38 and a target speed V of the transport roller 87. These target speeds U and V are generated based on a predetermined target speed characteristic (target speed profile) with time on the horizontal axis and speed on the vertical axis. This target speed characteristic is stored in an internal memory (not shown) in the target speed generation unit 103. In the present embodiment, when the target speed of the first motor 71 when driving the carriage 38 and the transport roller 87 at the target speeds U and V is X, and the target speed of the second motor 72 is Y as well, the target speed is generated. The unit 103 uses the rotational speed transmission ratios a and b to generate a target speed U (= aX + bY) represented by a linear expression of the target speed X and the target speed Y and the rotational speed transmission ratios c and d. A target speed V (= cX + dY) represented by a linear expression of the speed X and the target speed Y is generated. The target speeds U and V are expressed by the following equation (2) using the matrix A of the above equation (1). The target speeds U and V generated by the target speed generation unit 103 are output to the drive amount conversion unit 105.

A target speed U of the carriage 38 and a target speed V of the transport roller 87 generated by the target speed generator 103 are input to the drive amount converter 105. The driving amount conversion unit 105 multiplies the set of input target speeds (U, V), that is, the vector (U, V) having the input target speed as an element, by the inverse matrix A ⁻¹ of the matrix A. Processing is performed. Thereby, the target speeds U and V are converted into the speeds X and Y. The converted speeds X and Y are output to the calculation unit 102. Such a conversion process is represented by the following equation (3) using the inverse matrix A- ¹ .

An optical sensor 35 and an optical sensor 83 are connected to the drive amount conversion unit 106. Detection signals output from the optical sensor 35 and the optical sensor 83 are input to the drive amount converter 106. The drive amount converter 106 obtains the movement position of the carriage 38 (corresponding to the position information of the present invention) based on the detection signal from the optical sensor 35. Specifically, the number of pulses included in the detection signal is counted, and a distance according to the count value is calculated as a separation distance (movement position) from a predetermined reference position (for example, a standby position). Thereby, the position information of the carriage 38 with the reference position as a reference is obtained. Further, the actual moving speed U ′ of the carriage 38 is obtained from the position information of the carriage 38 and the count time. Further, the drive amount conversion unit 106 obtains the rotation position of the transport roller 87 (corresponding to the position information of the present invention) based on the detection signal from the optical sensor 83. Specifically, the number of pulses included in the detection signal is counted, and a rotation angle corresponding to the count value is calculated as rotation position information. Further, the actual rotational speed V ′ of the transport roller 87 is obtained from the rotation angle of the transport roller 87 and the count time. In the driving amount conversion unit 106, the inverse matrix A ^{− of the} matrix A is obtained with respect to the obtained speed pair (U ′, V ′), that is, the vector (U ′, V ′) having the obtained speed as an element. ^A process of multiplying by ¹ is performed. Thereby, the speeds U ′ and V ′ are converted into the speeds X ′ and Y ′. The converted speeds X ′ and Y ′ are output to the calculation unit 102.

The calculation unit 102 generates signals S _X and S _Y for determining the drive current output from the drive current conversion unit 104 to the first motor 71 and the second motor 72. This generation processing is realized, for example, by performing arithmetic processing and data processing according to a program stored in the ROM. In the conventional control system, the target speeds U and V and the speeds U ′ and V ′ are directly input to the calculation unit 102, and the drive current of the motor is determined based on these speed deviations. However, in the present embodiment, in the calculation unit 102, the signal S _X according to the deviation between the input speed X and the speed X ′ and the signal S _Y according to the deviation between the speed Y and the speed Y ′ are obtained. Generated. The signal S _X includes information indicating a drive current value required to rotate the first motor 71 at the rotational speed X, and the signal _SY includes the second motor 72 at the rotational speed Y. Information indicating a drive current value necessary for rotation is included. These signals S _X and S _Y are output to the drive current converter 104.

In the present embodiment, the signals S _X and S _Y are generated by performing arithmetic processing and data processing according to a program in the ROM. However, for example, electronic components such as capacitors and transistors are used. Arithmetic processing executed by the CPU or processing executed by the drive amount converters 105 and 106 may be realized by an ASIC having a logic circuit.

A driving current conversion unit 104 is connected to the calculation unit 102. The signals S _X and S _Y generated by the calculation unit 102 are input to the drive current conversion unit 104. The drive current converter 104 is supplied with power of a predetermined voltage (for example, DC 24V) from a power source (not shown). In the driving current converter 104, the driving current I _X corresponding to the signal S _X is generated, the driving current I _Y corresponding to the signal S _Y is generated. As shown in FIG. 6, the drive current I _X is supplied to the first motor 71, and the drive current I _Y is supplied to the second motor 72.

The first motor 71 that has received the drive current I _X is ideally rotated at the rotation speed X corresponding to the drive current I _X. Similarly, the second motor 72 that has received the drive current I _Y is ideally rotated at a rotational speed Y corresponding to the drive current I _Y. However, in actuality, since the frictional resistance is not constant and is affected by the eccentricity of the motor shaft, the actual rotational speed does not match the target speed, and the first motor 71 does not match the rotational speed X. The second motor 72 rotates at a rotational speed Y ′ that does not coincide with the rotational speed Y.

  When the first motor 71 rotates at the rotational speed X ′ and the second motor 72 rotates at the rotational speed Y ′, the output shaft 117A of the differential gear 111A has a rotational speed u ′ = aX ′ from the above equation (1). Rotate at + bY '. That is, the rotational speed of the output shaft 117A is the sum of a times the rotational speed X ′ of the first motor 72 and b times the rotational speed Y ′ of the second motor 72. In this embodiment, since the rotational speed transmission ratio a is “−1” and the rotational speed transmission ratio b is “−1”, the output shaft 117A rotates at the rotational speed u ′ = − X′−Y ′. To do. At this time, the carriage 38 moves at a moving speed U ′ = p (aX ′ + bY ′) obtained by multiplying the rotational speed u ′ by the transmission ratio p of the belt driving mechanism 46. In this embodiment, since the transmission ratio p is “1”, the carriage 38 moves at a moving speed U ′ = − X′−Y ′.

  On the other hand, when the first motor 71 rotates at the rotational speed X ′ and the second motor 72 rotates at the rotational speed Y ′, the output shaft 117B of the differential gear 111B has a rotational speed v ′ = Rotate with cX '+ dY'. That is, the rotation speed of the output shaft 117B is the sum of c times the rotation speed X ′ of the first motor 72 and d times the rotation speed Y ′ of the second motor 72. In this embodiment, since the rotational speed transmission ratio c is “−1” and the rotational speed transmission ratio d is “1”, the output shaft 117B rotates at the rotational speed v ′ = − X ′ + Y ′. At this time, the transport roller 87 rotates at a rotational speed V ′ = q (cX ′ + dY ′) obtained by multiplying the rotational speed v ′ by the transmission ratio q of the gear drive mechanism 85. In this embodiment, since the transmission ratio q is “1”, the transport roller 87 rotates at the rotation speed V ′ = − X ′ + Y ′.

In the present embodiment, when the first motor 71 and the second motor 72 are driven and controlled by the drive currents I _X and I _Y , the moving speed of the carriage 38 changes with time t as indicated by the broken line 62 in FIG. The rotational speed of the transport roller 87 changes with time t as indicated by a broken line 61 in FIG. However, in actuality, since the frictional resistance is not constant and is affected by the eccentricity of the motor shaft, the carriage 38 moves at the moving speed U ′ described above, and the transport roller 87 rotates at the rotating speed V ′ described above. However, the actual speeds of the carriage 38 and the transport roller 87 are detected by the optical sensors 35 and 83, and the detection results are fed back to the driver 100. Therefore, the carriage 38 and the conveyance roller 87 are always maintained at a speed close to the ideal speed.

[Transition of rotational speed X ′ and rotational speed Y ′]
The first motor 71 and the second motor 72 are connected to the differential transmission mechanism 110 configured as described above, and the first motor 71 and the second motor 72 are feedback-controlled by the driver 100, thereby the first motor 71. The rotational speed X ′ of the second motor 72 changes with time t as shown by the solid line 63 in FIG. 7, and the rotational speed Y ′ of the second motor 72 changes with time t as shown by the dotted line 64 of FIG. That is, when the first motor 71 and the second motor 72 are driven and controlled by the drive currents I _X and I _Y , the rotational speed X ′ and the rotational speed Y ′ change as indicated by the solid line 63 and the dotted line 64 in FIG. . Thereby, the carriage 38 and the conveyance roller 87 can be driven as indicated by broken lines 61 and 62 in FIG. Hereinafter, the transition of the rotational speed X ′ and the rotational speed Y ′ will be described in detail with reference to FIG. In the following, in order to simplify the description, it is assumed that the first motor 71 and the second motor 72 are motors having the same capacity and the same size. Further, the rotation speed transmission ratios a to d, the transmission ratios p and q, and the gear ratios of the pinion gears 122A and 122B will be described by substituting the specific numerical values described above.

A section t1 is a constant speed drive region of the carriage 38 and also a stop region of the transport roller 87. In the section t1, the first motor 71 is rotationally driven with the drive current I _X and the second motor 72 is rotationally driven with the drive current I _Y , and the same rotational direction at substantially the same rotational speed X ′ _t1 (= Y ′ _t1 ). To be rotated. At this time, in the differential gear 111A, since the input shaft 114A and the input shaft 115A are rotated in the same rotational direction at substantially the same rotational speed, the output shaft 117A is rotated by the rotational speed of the input shaft 114A and the rotational speed of the input shaft 115A. Rotate at a rotation speed (−X ′ _t1 −Y ′ _t1 ) = − 2X ′ _t1 . On the other hand, in the differential gear 111B, since the input shaft 114B and the input shaft 115B are rotated in the opposite directions at the same rotational speed, the output shaft 117B does not rotate (−X ′ _t1 − (− Y ′ _t1) = 0). . Accordingly, the carriage 38 is moved at a constant speed (−2X ′ _t1 ), and the transport roller 87 is kept stopped.

The section t2 is a deceleration driving area for the carriage 38 and an acceleration driving area for the transport roller 87. The drive current I _X is the same size in the section t2 as in the section t1. Since this drive current I _X is supplied to the first motor 71, the first motor 71 is rotated at the same rotational speed X ′ _t2 (= X ′ _t1 ) as in the section t1. Further, in the section t2, the driving current _{I Y} is lowered, the rotational speed Y _'t2 of the second motor 72 is gradually lowered. At this time, in the differential gear 111A, the input shaft 114A and the input shaft 115A are in the same rotational direction, but the rotational speed of the input shaft 115A is reduced due to the deceleration of the second motor 72, so the rotational speed of the output shaft 117A gradually increases. descend. Thereby, the moving speed of the carriage 38 is gradually reduced. When the carriage 38 decelerates, the kinetic energy of the carriage 38 that has moved at a predetermined speed acts on the output shaft 117A as an external force that rotates the output shaft 117A via the belt drive mechanism 46. At this time, the external force that rotates the output shaft 117A is transmitted to the input shafts 114A and 115A via the differential gear 11A, and further from the first transmission unit 130 and the second transmission unit 135 to the output shaft of the differential gear 111B. 117B, which is transmitted to the gear drive mechanism 85 and used as a driving force for accelerating the transport roller 87. That is, when the carriage 38 decelerates, the kinetic energy is not wasted but is used as energy for increasing the speed of the transport roller 87.

  On the other hand, in the differential gear 111B, when the rotation speed of the input shaft 115B is reduced by the deceleration of the second motor 72, the amount of the deceleration acts on the output shaft 117B as a force for rotating the output shaft 117B. Further, as described above, the kinetic energy of the carriage 38 is diverted and acts on the output shaft 117B as a force for rotating the output shaft 117B. As a result, the output shaft 117B begins to rotate, and the conveyance roller 87 starts to rotate.

Sections t3 and t4 are areas where the carriage 38 decelerates, stops, and accelerates, and are also constant speed drive areas of the transport roller 87. In the section t3, since the drive current I _X is decreased, the rotation speed X ′ _t3 of the first motor 71 is gradually decreased. Decrease in rotational speed X _'t3 of the first motor 71 is continued until the middle of the interval t4, then the first motor 71 is paused. Immediately thereafter, in the section t4, the reverse current I _X (<0) is supplied to the first motor 71, and the first motor 71 is accelerated in the reverse rotation direction. On the other hand, the drive current I _Y is further decreased in the section t3, and the second motor 72 is temporarily stopped. Then, immediately reverse current _I Y (<0) is supplied to the second motor 72, the reverse current _I Y from interval t3 to interval t4 (<0) is supplied to the second motor 72. As a result, the second motor 72 is accelerated in the reverse rotation direction.

In the present embodiment, in the section t3, the acceleration of the transport roller 87 is completed and constant speed driving is performed. On the other hand, the carriage 38 is gradually decelerated and its moving direction is reversed in the section t4. In the section t3 and the section t4, during the constant speed driving of the transport roller 87, the reverse currents I _X (<0) and I _Y (<0) supplied to the motors 71 and 72 change the rotation speed of the output shaft 117A. It is used for lowering and reversing the rotation direction of the output shaft 117A. That is, it is used to reverse the moving direction of the carriage 38. In the sections t3 and t4, the torques of the two motors 71 and 72 are transmitted from the output shaft 117A to the carriage 38.

The section t <b> 5 is an acceleration drive region in the reverse direction of the carriage 38 and is also a deceleration drive region of the transport roller 87. In the section t5, the reverse current I _X (<0) further increases, and the rotational speed X ′ _t5 of the first motor 71 gradually increases. On the other hand, the reverse current I _Y (<0) becomes constant, and the second motor 72 is rotationally driven at a constant speed Y ′ _t5 . At this time, in the differential gear 111B, the input shaft 114B and the input shaft 115B rotate in opposite directions, but the rotational speed difference between the respective shafts gradually decreases. For this reason, the rotation speed of the output shaft 117B gradually decreases. That is, the conveyance roller 87 is gradually decelerated. When the transport roller 87 decelerates, the kinetic energy of the transport roller 87 rotating at a predetermined speed acts as an external force for rotating the output shaft 117B via the gear drive mechanism 885 and acts on the output shaft 117B. At this time, the external force that rotates the output shaft 117B is transmitted to the input shafts 114B and 115B via the differential gear 111B, and further from the first transmission unit 130 and the second transmission unit 135 to the output shaft 117A of the differential gear 111A. Then, it is transmitted to the belt driving mechanism 46 and used as a driving force for accelerating the carriage 38.

  On the other hand, in the differential gear 111A, the input shaft 114A and the input shaft 115A are rotated in the same rotational direction. However, since the rotation of the input shaft 115A is changed from the acceleration drive to the constant speed drive, the rotation speed of the output shaft 117A is the first. The speed is increased by one motor 71. Further, as described above, the kinetic energy of the transport roller 87 is diverted to become an external force that rotates the output shaft 117A and acts on the output shaft 117A, so that the rotation of the output shaft 117A is accelerated by the external force. . That is, the transport roller 87 is accelerated by the first motor 71 and the external force.

The section t6 is a region where the reverse acceleration of the carriage 38 is finished and driven at a constant speed, and is also a region where the deceleration of the transport roller 87 is finished and stopped. In the section t6, the reverse currents I _X (<0) and I _Y (<0) are both constant, and the motors 71 and 72 are both rotationally driven in the reverse direction at a constant speed X ′ _t6 (= Y ′ _t6 ). . At this time, in the differential gear 111A, since the input shaft 114A and the input shaft 115A are rotated in the same rotational direction at the same rotational speed, the output shaft 117A is rotated by adding the input shaft 114A and the input shaft 115A ( _{-X 't6 -Y' t6) =} - 2X ' rotates at _t6. On the other hand, in the differential gear 111B, since the input shaft 114B and the input shaft 115B are rotated in the opposite directions at the same rotational speed, the output shaft 117B does not rotate (−X ′ _t6 − (− Y ′ _t6 ) = 0. ). Therefore, the carriage 38 is moved in the reverse direction at a constant speed (−2X ′ _t6 ), and the transport roller 87 is kept stopped.

  In the section t7 to the section t10, the motors 71 and 72 are driven and controlled in the reverse order to the above-described sections t2 to t5, whereby the carriage 38 is decelerated, paused, and accelerated, and the transport roller 87 acceleration driving, constant speed driving, and deceleration driving are performed. In the section t6, the motors 71 and 72 are controlled in reverse to the motor control in the section t1, whereby the carriage 38 is driven at a constant speed and the conveying roller 87 is temporarily stopped.

[Function and effect]
In this way, the first motor 71 and the second motor 72 are connected to the differential transmission mechanism 110, and the first motor 71 and the second motor 72 are feedback-controlled by the driver 100. Even while the motor is stopped, the rotational driving forces of both the motors 71 and 72 can be used to move the carriage 38. In addition, while the transport roller 87 is stopped, the torques of the two motors 71 and 72 can be applied to the carriage 38. Therefore, even when a motor having a small motor capacity is used, the carriage 38 can be driven smoothly. That is, when the first motor 71 and the second motor 72 are driven while the carriage 38 is at a high load and the transport roller 87 is at a low load, the driving forces of the first motor 71 and the second motor 72 are the carriage 38. The conveying roller 87 can be optimally distributed to each driven body.

  Further, during the drive control of the carriage 38 and the transport roller 87, the motors 71 and 72 always rotate at a relatively high speed even when either the carriage 38 or the transport roller 87 is driven at a low speed. A relatively large torque can be obtained when the carriage 38 or the conveying roller 87 is driven at a low speed. Even when either the carriage 38 or the transport roller 87 is stopped, the driving torque of both the first motor 71 and the second motor 72 is applied to the other driven body, so that a large torque is required. The present invention is also suitable at the time of rising.

  Further, when the transmission mechanism of the carriage 38 and the transmission mechanism of the conveyance roller 87 are completely independent as in the conventional mechanism, each of the carriage 38 and the conveyance roller 87 has at the time of deceleration of the carriage 38 and the conveyance roller 87. In the differential drive mechanism 110 of the present invention, in which the kinetic energy is converted to heat or the like and is wasted, when the carriage 38 decelerates, the kinetic energy is diverted as the driving force of the transport roller 87 and is transported. When the roller 87 decelerates, the kinetic energy is diverted as the driving force for the carriage 38. Therefore, energy can be effectively used in the differential drive mechanism 110. Moreover, the power consumption at the time of deceleration can be suppressed compared with the past.

  The above-described embodiment is merely an example of the present invention, and it is needless to say that the embodiment can be appropriately changed without departing from the gist of the present invention. For example, in the above-described embodiment, the rotational speed transmission ratio a is set to “−1” and b is set in the differential transmission mechanism 110 in consideration of the symmetry that the conveyance roller 87 and the carriage 38 are driven almost alternately. “−1”, c is “−1”, and d is “1”, but the rotational speed transmission ratios a to d are design elements, and if the condition of ad−bc ≠ 0 is satisfied, the rotational speed transmission is performed. The ratios a to d can be appropriately changed to arbitrary values according to the required operation and speed of the carriage 38 and the transport roller 87. In general, the rotation speed transmission ratios a to d may be set so that the rotation speed u of the output shaft 117A and the rotation speed of the output shaft v satisfy the following expression (4).

  In the embodiment described above, the position information of the carriage 38 is detected by the optical sensor 35, the position information of the conveyance roller 87 is detected by the optical sensor 83, and the detection result is fed back to the driver 100 to feed back the first motor 71. The optical sensor 107 for measuring (acquiring) the rotational speeds of the first motor 71 and the second motor 72, for example, as shown in the modification of FIG. (An example of the first rotation information acquisition unit of the present invention) and an optical sensor 108 (an example of the second rotation information acquisition unit of the present invention) are provided, and the rotational speed X ′ (the rotation information of the present invention) measured by the optical sensor 107 is provided. To the calculation unit 102 of the driver 100, and the rotational speed Y ′ (corresponding to the rotation information of the present invention) measured by the optical sensor 108 is output. It is also possible to adopt a configuration for feeding back to the computing unit 102 of the driver 100. In this case, since the actual rotational speeds of the first motor 71 and the second motor 72 are directly input to the calculation unit 102, the drive amount conversion unit 106 is unnecessary. In addition, about the process in the calculating part 102, since it is the same as that of the above-mentioned embodiment, the description is abbreviate | omitted.

  In the above-described embodiment, the example in which the present invention is applied to the first motor 71 and the second motor 72 that are used to drive the carriage 38 and the transport roller 87 in the printer unit 2 has been described. Among the two driven bodies that are driven and controlled by 71 and 72, the present invention can be applied to all driving mechanisms in which when the load on one driven body is large, the load on the other driven body is reduced. Thus, for example, in a biped robot, when each leg is driven by two motors, one leg is driven in the forward direction, and the other leg supports the own weight of the robot. The present invention can also be applied to the mechanism.

Further, the present invention can be applied to a mechanism having at least two motors and at least two driven bodies driven by the motors. In addition to the biped robot described above, three legs are provided. The present invention can also be applied to a mechanism for driving the above-described multi-legged walking robot using three or more motors and three or more differential gears. Here, in a differential drive mechanism having N input shafts to which driving force is input from each of N (N is 3 or more) motors and having N output shafts, Assuming that a vector having the rotational speed as an element is a vector U _N and a vector having the rotational speed of each motor as an element is a vector X _N , the vector U _N and the vector X _N reach from each motor rotation axis to each output axis. It can be expressed as the following equation (5) using an N × N matrix A indicating the transmission ratio. However, this matrix A satisfies detA ≠ 0.

  By configuring the differential drive mechanism so as to satisfy the above formula (5), even in a mechanism having three or more input shafts and output shafts, the same effects as those of the above-described embodiment can be obtained.

FIG. 1 is a perspective view showing an external configuration of the multifunction machine 1. FIG. 2 is a partially enlarged cross-sectional view showing the main configuration of the printer unit 2. FIG. 3 is a plan view showing the main configuration of the printer unit 2, and mainly shows the configuration on the back side of the apparatus from the approximate center of the printer unit 2. FIG. 4 is a model diagram schematically showing the differential transmission mechanism 110. FIG. 5 is a schematic diagram schematically showing a schematic configuration of the differential gear 111A. FIG. 6 is a block diagram schematically showing a schematic configuration of motor drive control by the motor driver 100. FIG. 7 is a graph showing speed characteristics (speed change) of the carriage 38, the transport roller 87, the first motor 71, and the second motor 72. FIG. 8 is a block diagram schematically showing a schematic configuration of motor drive control which is a modification of the embodiment of the present invention. FIG. 9 is a block diagram showing a schematic configuration of a conventional feedback control system applied to a conventional image recording apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... MFP 2 ... Printer part 24 ... Image recording unit 25 ... Paper feed roller 35 ... Optical sensor 46 ... Belt drive mechanism 71 ... 1st motor 72 ... Second motor 74 ... Rotating shaft 75 ... Rotating shaft 83 ... Optical sensor 85 ... Gear drive mechanism 87 ... Conveying roller 100 ... Motor driver 102 ... Calculation unit 103 ... Target speed generation unit 104 ... drive current conversion unit 105 ... drive amount conversion unit 106 ... drive amount conversion unit 107 ... optical sensor 108 ... optical sensor 110 ... differential transmission mechanism 111A, B ... Differential gear 114A, B ... Input shaft 115A, B ... Input shaft 117A, B ... Output shaft 130 ... First transmission part 135 ... Second transmission part

Claims (7)

A driving force transmission device for transmitting the driving force of the first motor and the second motor, whose rotation speeds are independently controlled by a predetermined control means, to the first driven body and the second driven body,
A first input shaft coupled to the first rotating shaft of the first motor; a second input shaft coupled to the second rotating shaft of the second motor; and a first output coupled to the first driven body. A first differential with a shaft;
A third input shaft coupled to the first rotating shaft of the first motor; a fourth input shaft coupled to the second rotating shaft of the second motor; and a second output coupled to the second driven body. A second differential with a shaft,
The rotational speed of the first output shaft is a sum of a times the rotational speed of the first motor and b times the rotational speed of the second motor;
The rotational speed of the second output shaft is a sum of c times the rotational speed of the first motor and d times the rotational speed of the second motor;
A driving force transmission device in which a relationship of ad−bc ≠ 0 is established between each of a, b, c, and d. A first transmission means provided in a path from the first rotation shaft to the first output shaft through the first input shaft, the transmission ratio of the a;
Provided in a path from the second rotating shaft to the first output shaft through the second input shaft, and a transmission ratio of b,
Provided in a path from the first rotating shaft to the second output shaft through the third input shaft, and a transmission ratio of c,
2. The driving force transmission device according to claim 1, further comprising: a fourth transmission unit that is provided in a path from the second rotation shaft to the second output shaft through the fourth input shaft and having a transmission ratio of d. . Said a is a transmission ratio of a pathway leading to the first input shaft from the first rotation shaft of the first transmission means and a _1, a transmission ratio in the first differential unit When a _2, a ₁ a ₂ ,
Said b is the transmission ratio of the path to the second input shaft from the second rotation axis of the second transmission means and b _1, when the transmission ratio in the first differential device and b _2, b ₁ b ₂ ,
Said c is the transmission ratio of the path to the third input shaft from said first rotation axis of the third transmission means and c _1, when the transmission ratio in the second differential unit and c _2, c ₁ c ₂ ,
The above d is the transmission ratio of the path to the fourth input shaft from the second rotation axis of the fourth transmission means and d _1, the transmission ratio in the second differential device When d _2, d The driving force transmission device according to claim _2, which is ₁ d ₂ .   4. The driving force transmission device according to claim 1, wherein a relationship of a = b and c = -d is established between each of the a, b, c, and d. First rotation information acquisition means for acquiring rotation information of the first motor;
A second rotation information acquisition means for acquiring rotation information of the second motor;
5. The control unit according to claim 1, wherein the control unit feedback-controls the first motor and the second motor based on acquisition results of the first rotation information acquisition unit and the second rotation information acquisition unit. A driving force transmission device according to claim 1. First position information acquisition means for acquiring position information of the first driven body;
A second position information acquisition means for acquiring position information of the second driven body;
5. The control unit according to claim 1, wherein the control unit feedback-controls the first motor and the second motor based on acquisition results of the first position information acquisition unit and the second position information acquisition unit. A driving force transmission device according to claim 1. An inkjet recording type image recording apparatus comprising the driving force transmission device according to any one of claims 1 to 6,
The first driven body is a carriage reciprocated in a direction crossing a conveyance direction of a recording medium;
An image recording apparatus, wherein the second driven body is a conveyance roller that conveys a recording medium toward an image recording area by a recording head.

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