JP4362815B2 - Platen gap adjusting device, printing device, and motor control device - Google Patents

Description

  The present invention relates to a platen gap adjusting device, a printing device, and a motor control device, and in particular, a platen gap as a distance between an ink discharge portion formed on a print head and a platen that supports a printing medium such as printing paper. The present invention relates to a platen gap adjusting device to be adjusted, a printing device including such a platen gap adjusting device, and a motor control device that generalizes the control thereof.

  Currently, inkjet printers that are widely used in ordinary homes and offices include plain paper used for normal document printing, photographic paper used for photo printing, transparent films such as stickers, OHP sheets, and CDs. An increasing number of models are capable of using various print media as print targets, such as -R, DVD-R, thick paper thicker than plain paper and photographic paper.

  On the other hand, in order to achieve high image quality printing in an inkjet printer, the platen gap as the distance between the ink discharge portion formed on the print head and the platen that supports the print medium needs to be appropriately adjusted. is there. In other words, an ink jet printer performs printing by ejecting ink from an ink ejection section to the surface of a print medium while reciprocating a carriage having a print head at high speed in the main scanning direction orthogonal to the print medium conveyance direction. For this reason, in order to realize high-quality printing, the platen gap must be properly adjusted and always kept constant.

  On the other hand, the various types of print media described above typically have different thicknesses for each type.

  Since the portion of the print medium that is transported directly below the print head and temporarily stops and is to be printed is supported by the platen from the back side, the adjustment of the distance between the ink ejection portion and the print medium surface is eventually The adjustment is performed by adjusting the distance between the ink nozzle forming surface serving as the ink ejection unit and the platen surface. Normally, the platen gap is adjusted by changing the height of the carriage on which the print head is mounted.

  As the platen gap adjusting mechanism as described above, in addition to a manual mechanism for operating a lever or the like, several automatic adjusting mechanisms using a motor have been known so far (see, for example, Patent Document 1).

When a motor is used as a power source of the platen gap adjusting mechanism, there can be a configuration using, for example, a DC motor, a stepping motor, or the like as the motor.
Japanese Patent Application Laid-Open No. 10-211748

  However, the conventional platen gap adjusting mechanism using a DC motor can adjust the platen gap only in two stages of the maximum platen gap or the minimum platen gap using the bistable operation of the DC motor. That is, the conventional platen gap adjustment mechanism using a DC motor has a simple configuration that only rotates the DC motor to the upper limit or the lower limit of the platen gap, and does not have an accurate positioning function.

  However, since there are various types of printing media for inkjet printers as described above, a platen gap capable of automatically adjusting the platen gap in at least three or more stages. There is a great need for adjustment mechanisms.

  As one means for realizing a platen gap automatic adjustment mechanism of three or more stages, it is conceivable to attach an encoder to the platen gap adjustment mechanism. However, the encoder is expensive as a part attached to the platen gap adjustment mechanism. From the viewpoint of manufacturing cost, the configuration of a mass production printer is not realistic.

  As another means for realizing a platen gap automatic adjustment mechanism having three or more stages, it is conceivable to use a stepping motor capable of accurate positioning in a plurality of stages instead of a DC motor.

  However, when a stepping motor is adopted, a motor with a sufficient torque is required to avoid step-out, and in addition, in the case of a four-phase stepping motor, two drive bridge circuits are required. There is a demerit that the space occupied by the constituent members is increased and the manufacturing cost is increased.

  On the other hand, since only one driving bridge circuit is required for the DC motor and no step-out occurs, the constituent members can be arranged in a compact occupied space, which is advantageous from the viewpoint of manufacturing cost.

  However, as described above, in the conventional platen gap adjustment mechanism using a DC motor, only a two-stage platen gap adjustment can be realized in a configuration that does not use an encoder from the viewpoint of manufacturing cost.

  An object of the present invention is to enable the adoption of a DC motor as a power source from the viewpoint of manufacturing cost control, while accurately adjusting platen gaps in at least three or more stages in a compact configuration without using an encoder. It is to provide a platen gap adjusting device capable of performing the above, a printing device including such a platen gap adjusting device, and a motor control device that generalizes the control thereof.

According to the platen gap adjusting device according to the embodiment of the present invention,
As a guide member for reciprocating driving of a carriage on which a print head on which a plurality of ink discharge portions for discharging ink are formed is mounted, it is fixed to a carriage support shaft that supports the carriage, and has three or more different radius portions. A different diameter cam that is rotatable about the carriage support shaft as a central axis;
A flag fixing disk member fixed to the carriage support shaft and having a flag fixed to a peripheral portion corresponding to each of the three or more radius radii of the different diameter cam;
By fixing the carriage support shaft vertically below the carriage support shaft, contacting the peripheral edge of the different diameter cam, and setting the carriage support shaft to a height corresponding to the radius of the different diameter cam at the contact portion A different diameter cam support shaft for adjusting a platen gap as a distance between an ink discharge portion forming surface of the print head and a platen that supports a print medium;
The flag corresponding to the radius of the different-diameter cam at the contact portion with the different-diameter cam support shaft and disposed around the flag fixing disk member so that the distance from the carriage support shaft is always constant. A flag sensor for detecting
A counter for counting the number of flag detections by the flag sensor;
It gradually increases after the start of rotational driving of the different diameter cam, decreases when any of the above flags is detected, and when the detected flag is not the target flag, it gradually increases again until the subsequent flag is detected. A torque controller that outputs a motor drive torque command and outputs a stop command after a lapse of a predetermined time after the motor drive torque is reduced when the detected flag is a target flag;
A motor driver that generates and outputs a motor drive signal based on a command from the torque controller;
A motor that rotationally drives the different-diameter cam in response to the motor drive signal;
It is characterized by having.

According to the printing apparatus according to the embodiment of the present invention,
A platen that supports the print medium;
A print head on which a plurality of ink discharge portions for discharging ink are formed;
A carriage carrying the print head;
Different diameters fixed to a carriage support shaft for supporting the carriage as a guide member for reciprocating driving of the carriage, having three or more different radius portions and rotatable about the carriage support shaft as a central axis With cam,
A flag fixing disk member fixed to the carriage support shaft and having a flag fixed to a peripheral portion corresponding to each of the three or more radius radii of the different diameter cam;
By fixing the carriage support shaft vertically below the carriage support shaft, contacting the peripheral edge of the different diameter cam, and setting the carriage support shaft to a height corresponding to the radius of the different diameter cam at the contact portion A different diameter cam support shaft for adjusting a platen gap as a distance between the ink discharge portion forming surface of the print head and the platen;
The flag corresponding to the radius of the different-diameter cam at the contact portion with the different-diameter cam support shaft and disposed around the flag fixing disk member so that the distance from the carriage support shaft is always constant. A flag sensor for detecting
A counter for counting the number of flag detections by the flag sensor;
It gradually increases after the start of rotational driving of the different diameter cam, decreases when any of the above flags is detected, and when the detected flag is not the target flag, it gradually increases again until the subsequent flag is detected. A torque controller that outputs a motor drive torque command and outputs a stop command after a lapse of a predetermined time after the motor drive torque is reduced when the detected flag is a target flag;
A motor driver that generates and outputs a motor drive signal based on a command from the torque controller;
A motor that rotationally drives the different-diameter cam in response to the motor drive signal;
It is characterized by having.

  In the above configuration of the platen gap adjusting device and the printing device according to an embodiment of the present invention, the torque controller gradually increases the motor driving torque in a plurality of stages after the rotation driving of the different diameter cam is started. A torque command should be output.

  The torque controller may output a motor drive torque command for gradually increasing the motor drive torque as the whole of the plurality of stages while increasing or decreasing the motor drive torque in each of the plurality of stages.

  In addition, when any of the above flags is detected, the torque controller avoids applying further driving torque to the motor according to the value of the immediately preceding motor driving torque, while the motor is running idle. It is preferable to output a motor drive torque command for reducing the motor drive torque to such an extent that the motor is naturally decelerated.

  The torque controller may output a braking command for decelerating the motor to such an extent that the motor does not stop immediately before or simultaneously with the decrease of the motor driving torque.

  Moreover, the said torque controller is good to change each value of the motor drive torque in a control process according to the rotation direction of the said different diameter cam.

  In addition, the torque controller measures the time from the start of the rotational drive of the different diameter cam to the detection of any of the flags, and the result of the rotation of the different diameter cam after the next time. It should be reflected in the drive control.

  It is preferable that a speed detection flag is further provided between the position detection flags, and the motor controller torque is gradually increased by the torque controller for each subdivided time period.

  The flag sensor may be an optical sensor including a light emitting unit and a light receiving unit that face each other across the passage route of the flag.

  The motor may be a DC motor.

According to the motor control device of one embodiment of the present invention,
Three or more flags provided for directly or indirectly detecting three or more possible positions of the drive object;
A flag sensor for detecting the flag corresponding to the current position of the driving object;
A counter for counting the number of flag detections by the flag sensor;
A motor having a value that gradually increases after the start of driving of the object to be driven, decreases when any of the flags is detected, and increases again until the subsequent flag is detected when the detected flag is not a target flag. A torque controller that outputs a drive torque command and outputs a stop command after a predetermined time has elapsed after the motor drive torque has been reduced when the detected flag is a target flag;
A motor driver that generates and outputs a motor drive signal based on a command from the torque controller;
A motor that drives the object to be driven in response to the motor drive signal;
It is characterized by having.

  In the above configuration of the motor control device according to an embodiment of the present invention, the torque controller outputs a motor drive torque command for gradually increasing the motor drive torque in a plurality of stages after the drive of the drive object is started. It is good to do.

  The torque controller may output a motor drive torque command for gradually increasing the motor drive torque as the whole of the plurality of stages while increasing or decreasing the motor drive torque in each of the plurality of stages.

  In addition, when any of the above flags is detected, the torque controller avoids applying further driving torque to the motor according to the value of the immediately preceding motor driving torque, while the motor is running idle. It is preferable to output a motor drive torque command for reducing the motor drive torque to such an extent that the motor is naturally decelerated.

  The torque controller may output a braking command for decelerating the motor to such an extent that the motor does not stop immediately before or simultaneously with the decrease of the motor driving torque.

  Moreover, the said torque controller is good to change each value of the motor drive torque in a control process according to the drive direction of the said drive target object.

  In addition, the torque controller measures the time from the start of driving of the drive object until any one of the flags is detected, and the measurement result is reflected in the subsequent drive control of the drive object. It is good to let you.

  It is preferable that a speed detection flag is further provided between the position detection flags, and the motor controller torque is gradually increased by the torque controller for each subdivided time period.

  The flag sensor may be an optical sensor including a light emitting unit and a light receiving unit that face each other across the passage route of the flag.

  The motor may be a DC motor.

  According to the platen gap adjusting apparatus and the printing apparatus according to the present invention, a DC motor can be adopted as a power source, and an accurate platen having three or more stages can be used while suppressing the manufacturing cost by eliminating an encoder. A platen gap adjusting device and a printing device capable of adjusting the gap can be realized with a compact configuration.

  The motor control device according to the present invention can realize motor control that generalizes the above control.

  First, a schematic configuration and control method of an ink jet printer which is a main application target of a platen gap adjusting device and a printing device according to the present invention will be described.

  FIG. 1 is a block diagram showing a schematic configuration of an inkjet printer.

  The ink jet printer shown in FIG. 1 discharges ink onto a paper feed motor (hereinafter also referred to as PF motor) 1 that feeds paper, a paper feed motor driver 2 that drives the paper feed motor 1, and printing paper 50. The head 9 is fixed, the carriage 3 is driven in a direction parallel to the printing paper 50 and perpendicular to the paper feeding direction, a carriage motor (hereinafter also referred to as a CR motor) 4 for driving the carriage 3, and a carriage motor. 4, a DC motor 6 that delivers a motor drive command value to the CR motor driver 5, a pump motor 7 that controls the suction of ink to prevent clogging of the head 9, and a pump motor 7 Motor driver 8 for driving the head, head driver 10 for driving and controlling the head 9, and linear fixed to the carriage 3. An encoder 11, a code plate 12 for a linear encoder 11 having slits formed at predetermined intervals, a rotary encoder 13 for the PF motor 1, and a paper detection sensor 15 for detecting the end position of the paper being printed. A CPU 16 that controls the entire printer, a timer IC 17 that periodically generates an interrupt signal to the CPU 16, and an interface unit (hereinafter also referred to as IF) 19 that transmits and receives data to and from the host computer 18. The ASIC 20 for controlling the print resolution, the drive waveform of the head 9 and the like based on the print information sent from the host computer 18 through the IF 19, and the PROM 21 and RAM 22 used as work areas and program storage areas of the ASIC 20 and the CPU 16. And EEPROM 23 and the printing paper 50 supporting paper. It comprises a ten 25, a transport roller 27 that is driven by the PF motor 1 to transport the printing paper 50, a pulley 30 that is attached to the rotating shaft of the CR motor 4, and a timing belt 31 that is driven by the pulley 30. Yes.

  The DC unit 6 drives and controls the paper feed motor driver 2 and the CR motor driver 5 based on the control command sent from the CPU 16 and the outputs of the encoders 11 and 13. Further, both the paper feed motor 1 and the CR motor 4 are constituted by DC motors.

  FIG. 2 is a perspective view showing a configuration around the carriage 3 of the ink jet printer.

  As shown in FIG. 2, the carriage 3 is connected to the carriage motor 4 via a pulley 30 by a timing belt 31 and is driven by a guide member 32 so as to move in parallel with the platen 25. A recording head 9 having a nozzle row for ejecting black ink and a nozzle row for ejecting color ink is provided on the surface of the carriage 3 facing the printing paper, and each nozzle is supplied with ink from the ink cartridge 34 for printing. Characters and images are printed by ejecting ink droplets on paper.

  Further, in the non-printing area of the carriage 3, a capping device 35 for sealing the nozzle openings of the recording head 9 at the time of non-printing and a pump unit 36 having the pump motor 7 shown in FIG. 1 are provided. . When the carriage 3 moves from the printing area to the non-printing area, the carriage 3 comes into contact with a lever (not shown), the capping device 35 moves upward, and the head 9 is sealed.

  When the nozzle opening row of the head 9 is clogged or when the ink is forcibly ejected from the head 9 by replacing the cartridge 34 or the like, the pump unit 36 is operated with the head 9 sealed. The ink is sucked out from the nozzle opening row by the negative pressure from the pump unit 36. As a result, dust and paper dust adhering to the vicinity of the nozzle opening row are washed, and air bubbles in the head 9 are discharged to the cap 37 together with ink.

  FIG. 3 is an explanatory diagram schematically showing the configuration of the linear encoder 11 attached to the carriage 3.

  The encoder 11 illustrated in FIG. 3 includes a light emitting diode 11a, a collimator lens 11b, and a detection processing unit 11c. The detection processing unit 11c includes a plurality (four) of photodiodes 11d, a signal processing circuit 11e, and two comparators 11fA and 11fB.

  When the voltage VCC is applied across the light emitting diode 11a via a resistor, light is emitted from the light emitting diode 11a. This light is condensed into parallel light by the collimator lens 11 b and passes through the code plate 12. The code plate 12 is provided with slits at predetermined intervals (for example, 1/180 inch (1 inch = 2.54 cm)).

  The parallel light that has passed through the code plate 12 enters each photodiode 11d through a fixed slit (not shown) and is converted into an electrical signal. The electric signals output from the four photodiodes 11d are processed in the signal processing circuit 11e, the signals output from the signal processing circuit 11e are compared in the comparators 11fA and 11fB, and the comparison result is output as a pulse. Pulses ENC-A and ENC-B output from the comparators 11fA and 11fB are output from the encoder 11.

  FIG. 4 is a timing chart showing waveforms of two output signals of the encoder 11 at the time of forward rotation and reverse rotation of the CR motor.

  As shown in FIGS. 4A and 4B, the phase of the pulse ENC-A and the pulse ENC-B differ by 90 degrees in both cases of CR motor forward rotation and reverse rotation. When the CR motor 4 is rotating forward, that is, when the carriage 3 is moving in the main scanning direction, the pulse ENC-A is 90 degrees from the pulse ENC-B as shown in FIG. When the phase is advanced only by the time and the CR motor 4 is reversely rotated, the encoder 4 is configured so that the phase of the pulse ENC-A is delayed by 90 degrees from the pulse ENC-B, as shown in FIG. ing. One period T of the pulse corresponds to the slit interval (for example, 1/180 inch) of the code plate 12, and is equal to the time for the carriage 3 to move the slit interval.

  On the other hand, the rotary encoder 13 for the PF motor 1 has the same configuration as that of the linear encoder 11 except that the code plate is a rotating disc that rotates in accordance with the rotation of the PF motor 1, and has two output pulses. ENC-A and ENC-B are output. In the ink jet printer, the slit interval of the plurality of slits provided on the code plate of the rotary encoder 13 for the PF motor 1 is 1/180 inch, and when the PF motor 1 rotates by the 1 slit interval, 1 / The paper is fed by 1440 inches.

FIG. 5 is a perspective view showing portions related to paper feed and paper detection.
The position of the paper detection sensor 15 shown in FIG. 1 will be described with reference to FIG. In FIG. 5, the printing paper 50 inserted into the paper feed insertion slot 61 of the printer 60 is fed into the printer 60 by a paper feed roller 64 driven by a paper feed motor 63. The leading edge of the printing paper 50 fed into the printer 60 is detected by, for example, the optical paper detection sensor 15. The paper 50 whose leading edge is detected by the paper detection sensor 15 is fed by the paper feed roller 65 and the driven roller 66 driven by the PF motor 1.

  Subsequently, printing is performed by dropping ink from a recording head (not shown) fixed to the carriage 3 that moves along the carriage guide member 32. When the paper is fed to a predetermined position, the end of the currently printed printing paper 50 is detected by the paper detection sensor 15. The printed paper 50 that has been printed is discharged from the paper discharge port 62 to the outside by the paper discharge roller 68 and the driven roller 69 driven by the gear 67C via the gears 67A and 67B driven by the PF motor 1. A rotary encoder 13 is connected to the rotation shaft of the paper feed roller 65.

  FIG. 6 is a perspective view showing in detail a portion related to paper feeding of the printer.

  Of the parts of the printer shown in FIG. 5, the parts related to paper feeding will be described in more detail with reference to FIGS.

  When the leading edge of the printing paper 50 inserted through the paper feed insertion port 61 of the printer 60 and fed into the printer 60 by the paper feed roller 64 is detected by the paper detection sensor 15, the PF motor 1 passes through the small gear 87. A paper feed roller 65 provided around a smap shaft 83 that is a rotation shaft of the driven large gear 67a and a holder 89 that presses the printing paper 50 fed from the paper feeding side downward in the vertical direction. The printing paper 50 is fed by a driven roller 66 provided at the front end of the paper feeding direction on the paper discharge side.

  The PF motor 1 is fixed to a frame 86 in the printer 60 with screws 85, a rotary encoder 13 is disposed at a predetermined location around the large gear 67a, and a smap shaft 83 which is a rotation shaft of the large gear 67a. A rotary encoder code plate 14 is connected to the encoder.

  The printing paper 50 that has been fed by the paper feeding roller 65 and the driven roller 66 passes over the platen 84 that supports the printing paper 50, and the small gear 87, the large gear 67 a, the intermediate gear 67 b, the small gear 88, and the like. The paper is fed between a paper discharge roller 68 driven by the PF motor 1 via a paper discharge gear 67c and a serrated roller 69 as a driven roller, and is fed to the outside through a paper discharge port 62.

  While the printing paper 50 is supported on the platen 84, the carriage 3 moves left and right along the guide member 32 in the space on the platen 84, and ink is ejected from a recording head (not shown) fixed to the carriage 3. Is discharged and printing is performed.

  Next, the configuration of the DC unit 6 that is a DC motor control device that controls the CR motor 4 of the ink jet printer described above, and a control method by the DC unit 6 will be described.

  FIG. 7 is a block diagram showing the configuration of the DC unit 6 that is a DC motor control device, and FIG. 8 is a graph showing the motor current and motor speed of the CR motor 4 controlled by the DC unit 6.

  The DC unit 6 shown in FIG. 7 includes a position calculator 6a, a subtractor 6b, a target speed calculator 6c, a speed calculator 6d, a subtractor 6e, a proportional element 6f, an integral element 6g, a differential It comprises an element 6h, an adder 6i, a D / A converter 6j, a timer 6k, and an acceleration controller 6m.

  The position calculator 6a detects the rising edge and the falling edge of each of the output pulses ENC-A and ENC-B of the encoder 11, counts the number of detected edges, and based on the counted value, the carriage 3 The position of is calculated. This count is incremented by “+1” when one edge is detected when the CR motor 4 is rotating in the forward direction, and “−1” when one edge is detected when the CR motor 4 is rotating in the reverse direction. Is added. The period of each of the pulses ENC-A and ENC-B is equal to the slit interval of the code plate 12, and the phase of the pulse ENC-A and the pulse ENC-B differ by 90 degrees. Therefore, the count value “1” of the count corresponds to ¼ of the slit interval of the code plate 12. Thus, if the count value is multiplied by 1/4 of the slit interval, the amount of movement from the position of the carriage 3 corresponding to the count value “0” can be obtained. At this time, the resolution of the encoder 11 is ¼ of the interval between the slits of the code plate 12. If the interval between the slits is 1/180 inch, the resolution is 1/720 inch.

  The subtractor 6b calculates a position deviation between the target position sent from the CPU 16 and the actual position of the carriage 3 obtained by the position calculation unit 6a.

  The target speed calculator 6c calculates the target speed of the carriage 3 based on the position deviation that is the output of the subtractor 6b. This calculation is performed by multiplying the position deviation by the gain KP. This gain KP is determined according to the position deviation. Note that the value of the gain KP may be stored in a table (not shown).

  The speed calculator 6 d calculates the speed of the carriage 3 based on the output pulses ENC-A and ENC-B of the encoder 11. This speed is obtained as follows. First, the rising edge and the falling edge of each of the output pulses ENC-A and ENC-B of the encoder 11 are detected, and the time interval between edges corresponding to 1/4 of the slit interval of the code plate 12 is determined by a timer counter. Count. If this count value is T and the slit interval of the code plate 12 is λ, the carriage speed can be obtained as λ / (4T). Here, the calculation of the speed is obtained by measuring one cycle of the output pulse ENC-A, for example, from the rising edge to the next rising edge with a timer counter.

  The subtractor 6e calculates a speed deviation between the target speed and the actual speed of the carriage 3 calculated by the speed calculation unit 6d.

  The proportional element 6f multiplies the speed deviation by a constant Gp and outputs the multiplication result. The integration element 6g integrates the speed deviation multiplied by a constant Gi. The differentiation element 6h multiplies the difference between the current speed deviation and the previous speed deviation by a constant Gd, and outputs the multiplication result. The calculation of the proportional element 6f, the integral element 6g, and the derivative element 6h is performed in synchronization with the rising edge of the output pulse ENC-A, for example, for each cycle of the output pulse ENC-A of the encoder 11.

  The outputs of the proportional element 6f, the integral element 6g, and the derivative element 6h are added by the adder 6i. Then, the addition result, that is, the driving current of the CR motor 4 is sent to the D / A converter 6j and converted into an analog current. The CR motor 4 is driven by the driver 5 based on the analog voltage.

  The timer 6k and the acceleration control unit 6m are used for acceleration control, and the PID control using the proportional element 6f, the integral element 6g, and the derivative element 6h is used for constant speed and deceleration control during acceleration.

  The timer 6k generates a timer interrupt signal every predetermined time based on the clock signal sent from the CPU 16.

  Each time the acceleration control unit 6m receives the timer interrupt signal, the acceleration control unit 6m integrates a predetermined current value (for example, 20 mA) to the target current value, and the integration result, that is, the target current value of the DC motor 4 during acceleration is D / A is sent to the A converter 6j. As in the case of PID control, the target current value is converted into an analog current by the D / A converter 6j, and the CR motor 4 is driven by the driver 5 based on this analog current.

  The driver 5 includes, for example, four transistors, and (a) an operation mode in which the CR motor 4 is rotated forward or reverse by turning each of the transistors on or off based on the output of the D / A converter 6j. b) Regenerative brake operation mode (short brake operation mode, i.e., mode in which the CR motor is stopped) and (c) mode in which the CR motor is to be stopped can be performed.

  Next, the operation of the DC unit 6, that is, the DC motor control method will be described with reference to FIGS. 8 (a) and 8 (b).

  When the start command signal for starting the CR motor 4 is sent from the CPU 16 to the DC unit 6 when the CR motor 4 is stopped, the start initial current value I0 is sent from the acceleration control unit 6m to the D / A converter 6j. It is done. This starting initial current value I0 is sent from the CPU 16 to the acceleration control unit 6m together with the starting command signal. The current value I0 is converted to an analog voltage by the D / A converter 6j and sent to the driver 5, and the CR motor 4 starts to be started by the driver 5 (see FIGS. 8A and 8B). After receiving the start command signal, a timer interrupt signal is generated from the timer 6k every predetermined time. Each time the acceleration control unit 6m receives a timer interrupt signal, the acceleration control unit 6m adds a predetermined current value (for example, 20 mA) to the startup initial current value I0, and sends the integrated current value to the D / A converter 6j. Then, the integrated current value is converted into an analog current by the D / A converter 6j and sent to the driver 5. Then, the CR motor is driven by the driver 5 and the speed of the CR motor 4 is increased so that the value of the current supplied to the CR motor 4 becomes the integrated current value (see FIG. 8B). For this reason, the current value supplied to the CR motor 4 is stepped as shown in FIG. At this time, the PID control system is also operating, but the D / A converter 6j selects and takes in the output of the acceleration control unit 6m.

  The integration process of the current value of the acceleration control unit 6m is performed until the integrated current value becomes a constant current value IS. When the current value integrated at time t1 reaches a predetermined value IS, the acceleration control unit 6m stops the integration process and supplies a constant current value IS to the D / A converter 6j. Thus, the driver 5 is driven so that the value of the current supplied to the CR motor 4 becomes the current value IS (see FIG. 8A).

  In order to prevent the speed of the CR motor 4 from overshooting, when the CR motor 4 reaches a predetermined speed V1 (see time t2), acceleration control is performed so as to reduce the current supplied to the CR motor 4. The unit 6m controls. At this time, the speed of the CR motor 4 further increases, but when the speed of the CR motor 4 reaches a predetermined speed Vc (see time t3 in FIG. 8B), the D / A converter 6j outputs the output of the PID control system. That is, the output of the adder 6i is selected and PID control is performed.

  That is, the target speed is calculated based on the position deviation between the target position and the actual position obtained from the output of the encoder 11, and based on the speed deviation between the target speed and the actual speed obtained from the output of the encoder 11. Thus, the proportional element 6f, the integral element 6g, and the differential element 6h operate to perform proportional, integral, and differential calculations, respectively, and the CR motor 4 is controlled based on the sum of these calculation results. The proportional, integral and differential calculations are performed in synchronization with the rising edge of the output pulse ENC-A of the encoder 11, for example. As a result, the speed of the DC motor 4 is controlled to a desired speed Ve. The predetermined speed Vc is preferably 70 to 80% of the desired speed Ve.

  Since the DC motor 4 has a desired speed from time t4, the carriage 3 also has a desired constant speed Ve, and printing processing can be performed.

  When the printing process is completed and the carriage 3 approaches the target position (see time t5 in FIG. 8B), the position deviation becomes small and the target speed also becomes small. Therefore, the speed deviation, that is, the output of the subtractor 6e is obtained. It becomes negative, the DC motor 4 is decelerated, and stops at time t6.

  The content of the drive control when the DC motor is the CR motor 4 has been described above, but the content of the drive control is substantially the same when the DC motor is the paper feed motor (PF motor) 1 or the paper feed motor. It will be a thing.

  Further, the contents of the drive control have been described by taking the energization method for the motor as an example based on current control, but the energization method for the motor may be based on PWM control (voltage control).

  In this case, the D / A converter 6j in FIG. 7 serves as a PWM signal generation unit, and the driver 5 controls energization to the motor by ON / OFF by the PWM signal. The PWM signal is a signal indicating the ON / OFF ratio in a certain period. That is, when the voltage is 100%, the applied voltage of the driver is supplied to the motor as it is, and when the voltage is 50%, half the voltage applied to the driver is equivalently supplied to the motor.

  The current value used in the description of the current value control is represented by the PWM signal as an ON / OFF ratio in the PWM control.

  In the ink jet printer whose overall configuration has been described above, plain paper used for normal document printing, photographic paper used for photo printing, transparent films such as stickers, OHP sheets, CD-R or DVD- R, it is required to be able to cope with printing on various printing media such as thick paper thicker than plain paper or photographic paper.

  On the other hand, in order to achieve high image quality printing in an inkjet printer, the platen gap as the distance between the ink discharge portion formed on the print head and the platen that supports the print medium needs to be appropriately adjusted. is there. In other words, the inkjet printer performs printing by ejecting ink from the ink ejection unit to the surface of the printing medium while reciprocating at high speed in the main scanning direction orthogonal to the printing medium conveyance direction, with the carriage mounted with the print head. In order to realize high-quality printing, the platen gap must be properly adjusted and always kept constant.

  On the other hand, since the various print media usually have different thicknesses for each type, in order to realize high-quality printing on various print media, each print medium having a specific thickness is used. In addition, it is necessary to appropriately adjust the platen gap of the printing apparatus.

  Since the portion of the print medium located in the printable area directly under the print head 36 is supported by the platen from the back surface, the adjustment of the distance between the ink discharge portion and the print medium surface is performed by the ink nozzle forming surface as the ink discharge portion. The platen gap is adjusted by changing the height of the carriage on which the print head is mounted.

  As the platen gap adjustment mechanism, in addition to a manual mechanism for operating a lever or the like, as described above, an automatic adjustment mechanism using a DC motor is known, but the automatic adjustment mechanism is a bistable operation of a DC motor. The platen gap can be adjusted only in two stages of the upper limit value and the lower limit value, and an accurate positioning function is not provided.

  However, since there are various types of printing media for ink jet printers as described above, platen gap adjustment in only two stages can handle only a small part of printing media. .

  Accordingly, there is a need for a platen gap adjusting mechanism that can automatically adjust the platen gap in at least three or more stages.

  However, an encoder attached to the platen gap adjustment mechanism in order to realize a platen gap automatic adjustment mechanism of three or more stages is not practical for mass production from the viewpoint of manufacturing cost, and a stepping motor instead of a DC motor is used. If used, it is difficult to realize from the viewpoint of the size of the occupied space and the manufacturing cost.

  On the other hand, the DC motor has an advantage that it occupies a small space and is cheaper than the stepping motor.

  Therefore, the platen gap adjusting device and the printing device according to the present invention can employ a DC motor as a power source, and can perform multi-stage positioning of at least three or more stages by using the configuration described later without using an encoder. As described above, a platen gap adjusting mechanism that can handle various printing media is realized.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a platen gap adjusting device and a printing device according to the present invention will be described with reference to the drawings.

  FIG. 9 is a side view illustrating a schematic configuration of each part of the carriage support shaft and the printing apparatus that constitute a part of the platen gap adjusting apparatus.

  A printing sheet 50 as a printing medium loaded in a sheet feeding tray 90 of the printing apparatus is fed out by a sheet feeding roller 64 and sandwiched between a sheet feeding roller (conveying roller) 65 and its driven roller 66, and then the platen 25. The paper passes under the print head 9 while being supported by the paper, and is sequentially conveyed downstream in the conveyance direction by the paper feed roller 65 and its driven roller 66.

  When the printing paper 50 passes over the paper detection sensor 15, the leading edge and the trailing edge of the printing paper 50 are detected by the paper detection sensor 15, and based on the detection timing and the paper feed amount by the paper feed roller 65. Then, the position control of the printing paper 50 is performed.

  When the printing paper 50 is conveyed downstream in the conveying direction by a predetermined paper feeding amount by the paper feeding roller 65 and its driven roller 66, the leading end of the printing paper 50 is sandwiched between the paper discharge roller 68 and its driven roller 69, When the printing paper 50 is further transported downstream in the transport direction, the paper is finally transported and discharged by the paper discharge roller 68 and its driven roller 69.

  Since the print head 9 is driven to reciprocate in the main scanning direction orthogonal to the sub-scanning direction as the print medium conveyance direction, the area immediately below the print head 9 is the printable area. Accordingly, when the print paper 50 passes under the print head 9, the print paper positioned in the printable area directly under the print head 9 while the print paper 50 is temporarily stopped for every fixed paper feed amount. Printing is performed on 50 surfaces.

  The print quality, that is, the image quality directly affects the distance between the ink nozzle formation surface of the print head 9 and the surface of the print paper 50, but the print paper 50 positioned in the printable area directly below the print head 9. As shown in FIG. 9, the printing paper 5 when printing is performed on the front surface is supported by the platen 25 from the back surface, so the distance between the ink nozzle formation surface of the printing head 9 and the surface of the printing paper 50. This adjustment is performed through adjustment of the distance between the ink nozzle forming surface of the print head 9 and the platen 25.

  Then, the adjustment of the distance between the ink nozzle forming surface of the print head 9 and the platen 25, that is, the adjustment of the platen gap is performed by changing the height of the carriage 3 on which the print head 9 is mounted.

  Specifically, the platen gap adjustment is performed by changing the height of the carriage support shaft 32 that is a guide member for reciprocating driving of the carriage 3 in the main scanning direction orthogonal to the print medium conveyance direction.

  The platen gap adjusting device and the printing device according to the present invention enable the adoption of a DC motor as a power source, while eliminating the encoder and suppressing the manufacturing cost while accurately adjusting the platen gap in three or more steps. That is, the height adjustment of the carriage support shaft 32 is realized with a compact configuration.

  FIG. 10 is a side view showing components attached to the carriage support shaft in the platen gap adjusting apparatus and the printing apparatus according to the present invention.

  The platen gap adjusting device and the printing device according to the present invention are provided on a carriage support shaft 32 that supports a carriage as a guide member for reciprocating driving of a carriage on which a print head on which a plurality of ink discharge portions for discharging ink are formed is mounted. A fixed-diameter cam 41 having different three-stage radii r1, r2, and r3 and capable of rotating about the carriage support shaft 32 as a central axis, and a fixed-diameter cam fixed to the carriage support shaft 32 41, a flag fixing disk member 43 having three flags f1, f2, and f3 fixed to peripheral portions corresponding to the three stages of radii r1, r2, and r3, respectively, and a vertically lower side of the carriage support shaft 32. The carriage support shaft 32 is set to a height corresponding to the radius of the different diameter cam 41 at the contact portion. For flag fixation so that the distance between the carriage support shaft 32 and the different diameter cam support shaft 42 for adjusting the platen gap as the distance between the ink discharge portion forming surface of the print head and the platen that supports the print medium is always constant. A flag sensor 40 that is disposed around the disk member 43 and detects a flag corresponding to the radius of the different-diameter cam 41 at a contact portion with the different-diameter cam support shaft 42, and a DC that rotationally drives the different-diameter cam 41. A motor (not shown).

  “Rotation” means rotation within a predetermined central angle range. Since the different diameter cam 41 operates within a range of a predetermined center angle, the operation is “turning”. However, in the DC motor that drives the different diameter cam 41 to rotate, the different diameter cam 41 has a predetermined center. Since the rotation operation is usually performed a plurality of times during the rotation from the start point to the end point within the corner range, the operation of the DC motor itself is “rotation”.

  The different-diameter cam 41 is formed by continuously forming different three-stage radii, that is, a first radius r1, a second radius r2, and a third radius r3 (r1 <r2 <r3). The carriage support shaft 32 is fixed as a central axis.

  The different diameter cam 41 is supported by a different diameter cam support shaft 42 from below in the vertical direction, whereby the height of the carriage support shaft 32 as the central axis of the different diameter cam 41 is set.

  Further, the different diameter cam 41 is rotationally driven by a DC motor, whereby the contact portion with the different diameter cam support shaft 42 is changed. As a result, the distance between the different-diameter cam support shaft 42 and the carriage support shaft 32 is changed to a height corresponding to the radius of the different-diameter cam 41 at the contact portion between the different-diameter cam 41 and the different-diameter cam support shaft 42. A carriage support shaft 32 is set.

  By changing and setting the height of the carriage support shaft 32 as described above, the distance between the ink nozzle formation surface of the print head and the platen is changed and set, and the platen gap is adjusted.

  FIG. 11 is a graph showing an example of a flag detection signal waveform by the flag sensor.

  As the flag sensor 40, for example, an optical sensor having a light emitting part and a light receiving part is used, and the first, second, and third flags f1, f2, and f3 are associated with the rotation of the flag fixing disk member 43. It is arranged around the flag fixing disk member 43 so as to pass between the light emitting part and the light receiving part and so that the distance from the carriage support shaft 32 is always constant. Accordingly, the light emitting unit and the light receiving unit of the optical sensor are disposed so as to face each other across the passage route of the flag. Further, the flag fixing position of the flag fixing disk member 43 and the flag sensor 40 are detected so that the flag sensor 40 detects a flag corresponding to the radius of the different diameter cam 41 at the portion in contact with the different diameter cam support shaft 42. The arrangement position of is adjusted.

  In the example of the graph of FIG. 11, when any one of the flags is located between the light emitting unit and the light receiving unit of the flag sensor 40 and blocks light from the light emitting unit, the sensor output is H (High). ) Level, there is no flag between the light emitting part and the light receiving part of the flag sensor 40, and the sensor output is at the L (Low) level when the light from the light emitting part is incident on the light receiving part as it is. The sensor output is set so that

  Therefore, the sensor output of the flag sensor 40 is sequentially monitored to detect the first, second, and third flags f1, f2, and f3, whereby the different diameter cam 41 at the contact portion with the different diameter cam support shaft 42 is obtained. Can be detected indirectly. In the initial stage of operation, the flag sensor 40 is currently detecting which of the first, second, and third flags f1, f2, and f3, or the first flag f1 and the second flag f2. Subsequent platen gap adjustment operation by specifying in advance whether the intermediate region between the flag f2 or the intermediate region between the second flag f2 and the third flag f3 is at the position of the flag sensor 40 Accordingly, when the flag sensor 40 newly detects a flag, it is possible to specify which flag is detected.

  However, if the different-diameter cam 41 rotates unintentionally after detecting the edge of a certain flag once, did the edge of the subsequent flag be detected by detecting the same edge of the flag again? It becomes impossible to identify whether the same edge of the flag is detected again, and the detected flag cannot be specified.

  Therefore, in the platen gap adjusting apparatus and the printing apparatus according to the present invention, as will be described in detail later, drive control is performed so that the different-diameter cam 41 does not reversely rotate unintentionally.

  FIG. 12 is a block diagram showing an electrical configuration of the platen gap adjusting apparatus and the printing apparatus according to the present invention.

  The platen gap adjusting device and the printing device according to the present invention include three pieces fixed to the peripheral portions of the flag fixing disk member 43 corresponding to the three-stage radii r1, r2, and r3 of the different diameter cam 41, respectively. Among the flags f1, f2, and f3, a flag sensor 40 that detects a flag corresponding to the radius of the different diameter cam 41 at a contact portion with the different diameter cam support shaft 42, and a counter that counts the number of flag detections by the flag sensor 40 101, motor drive torque having a value that gradually increases after the start of rotation driving of the different-diameter cam, decreases when the flag is detected, and increases again until the subsequent flag is detected when the detected flag is not the target flag A torque controller 100 that outputs a command and outputs a stop command when the detected flag is a target flag; A motor driver 102 which outputs to generate a motor drive signal based on the command, and a DC motor 103 which different-diameter cam 41 in accordance with a motor drive signal for driving rotation, the.

  As is apparent from the block diagram of FIG. 12, the platen gap adjusting operation and the printing apparatus according to the present invention are controlled by the operation of the DC motor that is the driving object as feedback to the torque controller 100 as the control device. Is open loop control.

  FIG. 13 is a flowchart showing operations of the platen gap adjusting device and the printing apparatus according to the present invention, and FIG. 14 is a graph showing motor drive torque command values of the platen gap adjusting apparatus and the printing apparatus according to the present invention. FIG. 14A is a graph in the case where the contact portion between the different diameter cam 41 and the different diameter cam support shaft 42 is moved by one radius of the different diameter cam, that is, by one flag. FIG. 14B is a graph in the case where the contact portion between the different-diameter cam 41 and the different-diameter cam support shaft 42 is continuously moved by the two-step radius of the different-diameter cam, that is, by two flags. It is.

  The operations of the platen gap adjusting device and the printing device according to the present invention can be summarized as follows. The driving torque of the DC motor 103 that is a power source of the platen gap adjusting operation is gradually increased every predetermined time, and the target flag, that is, the operation is stopped. The edge is detected by reducing the driving torque when the flag edge (end) at the position to be detected is detected, and continuing the driving operation for a predetermined time with the reduced driving torque, and then performing the braking control. In the state where the center portion of the target flag is detected by the flag sensor 40, that is, in the state where the different diameter cam support shaft 42 is in contact with the central portion of the different diameter cam 41 having the radius corresponding to the flag. The platen gap adjustment operation is terminated.

  Hereinafter, the operation of the embodiment of the platen gap adjusting apparatus and the printing apparatus according to the present invention will be described in detail with reference to FIGS.

  When the platen gap adjustment operation is started by the operation instruction input operation in the host computer or the printing apparatus main body connected to the printing apparatus, the torque controller 100 causes the motor to drive the motor for the time τ1 with the first torque T1. Outputs drive torque command. Then, the motor driver 102 generates a motor drive signal based on the motor drive torque command and outputs it to the DC motor 103. Further, the DC motor 103 rotates for the time τ1 (msec) with the first torque T1 in accordance with the motor drive signal, and rotationally drives the different diameter cam 41 (step S1). However, since the first torque T1 is smaller than the second and third torques T2 and T3, which will be described later (T1 <T2 <T3), does the different diameter cam 41 hardly rotate at this stage? Or, even if it rotates, it may stop halfway.

  As shown in FIG. 14, none of the first, second, and third torques T1, T2, and T3 is a constant value, and the values T1, T2, and T3 as a guide vary as a central value. It is a fluctuating value. In the graph of FIG. 14 as an example, the torque during the period of time τ1 gradually increases from a value smaller than the first torque T1, exceeds the value T1, and then decreases again to a value smaller than the value T1. The reason why the motor driving torque is finely increased and decreased in this way is to prevent the motor from being accelerated too much.

  Whether the edge of the flag is detected by the flag sensor 40 within the time τ1 (msec) after the start of the driving operation at the first torque T1, that is, whether the rising edge of the signal waveform in the graph of FIG. 11 is detected. Is determined by the torque controller 100 (step S2).

  If the flag edge is detected, the flag edge detection is counted by the counter 101 and the operation proceeds to step 8 described later.

  On the other hand, if the flag edge is not detected within the time τ1 (msec), the torque controller 100 outputs a motor drive torque command so that the motor is driven by the second torque T2 for the time τ2. Then, the motor driver 102 generates a motor drive signal based on the motor drive torque command and outputs it to the DC motor 103. Further, the DC motor 103 rotates for the time τ2 (msec) with the second torque T2 in accordance with the motor drive signal, and rotationally drives the different-diameter cam 41 (step S3).

  Whether the edge of the flag is detected by the flag sensor 40 within the time τ2 (msec) after the start of the driving operation with the second torque T2, that is, whether the rising edge of the signal waveform in the graph of FIG. 11 is detected. Is determined by the torque controller 100 (step S4).

  If the flag edge is detected, the flag edge detection is counted by the counter 101 and the operation proceeds to step 8 described later.

  On the other hand, if the flag edge is not detected within the time τ2 (msec), the torque controller 100 outputs a motor drive torque command so that the motor is driven for the time τ3 with the third torque T3. Then, the motor driver 102 generates a motor drive signal based on the motor drive torque command and outputs it to the DC motor 103. Further, the DC motor 103 rotates for the time τ3 (msec) with the third torque T3 in accordance with the motor drive signal, and rotationally drives the different diameter cam 41 (step S5). The third torque T3 is large enough to always rotate the different-diameter cam 41 regardless of where the different-diameter cam 41 and the different-diameter cam support shaft 42 come into contact. Keep it.

  As described above, the reason why the motor driving torque is increased step by step with the first torque T1, the second torque T2, and the third torque T3 is that the torques T1, T2, and T3 are increased or decreased finely. The reason is to prevent the motor from accelerating too much for the same reason.

  Whether or not the edge of the flag is detected by the flag sensor 40 within the time τ3 (msec) after the start of the driving operation at the third torque T3, that is, whether or not the rising edge of the signal waveform in the graph of FIG. 11 is detected. Is determined by the torque controller 100 (step S6).

  As described above, the third torque T3 is such that the different diameter cam 41 can always be rotated regardless of the contact portion between the different diameter cam 41 and the different diameter cam support shaft 42. If the flag edge is not detected within the time τ3 (msec), the platen gap adjustment operation is terminated as an operation error (step S7).

  On the other hand, including the case where the edge of the flag is detected in step S2 or step S4, when the edge of the flag is detected here, the edge detection of the flag is counted by the counter 101, and the torque controller 100 The motor drive torque is reduced to K% of the immediately preceding torque, and a motor drive torque command is output so that the drive operation is continued for the time τ4 with the reduced motor drive torque. Then, the motor driver 102 generates a motor drive signal based on the motor drive torque command and outputs it to the DC motor 103. Further, the DC motor 103 rotates for a time τ4 (msec) with a torque of K% of the immediately preceding torque in accordance with the motor drive signal, and rotationally drives the different diameter cam 41 (step S8). However, as will be described later, the torque of “K%” is a torque value that can avoid the application of further driving torque to the motor, that is, the degree that the motor naturally decelerates while idling. The torque of the value. Alternatively, the operation of the DC motor 103 and / or the different-diameter cam 41 may be decelerated by applying a brake that is weaker than the brake at the time of operation stop immediately before or simultaneously with reducing the motor drive torque to K% of the immediately preceding torque. Good. Accordingly, at this time, the torque controller 100 outputs a braking command for decelerating the motor to such an extent that the motor does not stop.

  In step 8, the motor driving torque is reduced to K% of the immediately preceding torque, and the driving operation is continued with the reduced motor driving torque for the following reason.

  That is, if the brake is immediately applied when the flag edge is detected and the braking control is performed, the operation of each part of the platen gap adjustment mechanism is stopped very close to the edge of the flag, corresponding to the flag. The operation stops when the different diameter cam support shaft 42 is in contact with the vicinity of the end of the portion of the different diameter cam 41 having the radius. Such a state cannot be said to be a sufficiently stable state, and the contact portion between the different-diameter cam 41 and the different-diameter cam support shaft 42 is displaced due to some impact such as an external impact, and as a result, There is a possibility that a large deviation occurs in the setting of the height of the carriage support shaft 32, that is, the setting of the platen gap.

  Therefore, the state where the center of the flag where the edge is detected is detected by the flag sensor 40, that is, the different-diameter cam support shaft 42 contacts the central portion of the different-diameter cam 41 having a radius corresponding to the flag. In other words, in order to stop the platen gap adjustment operation in a stable state, the driving operation is continued for the time τ4 after the flag edge is detected.

  However, at that time, if the driving operation is continued with the value of the motor driving torque at the time when the edge of the flag is detected, on the contrary, the driving force is too large, and the position before the opposite edge of the flag. The operation cannot be stopped at this point, but the opposite edge of the flag is passed, and the different diameter cam support shaft 42 hits the position passing the portion of the different diameter cam 41 having the radius corresponding to the flag. The operation stops in contact. As a result, the height of the carriage support shaft 32, that is, the setting of the platen gap cannot be accurately performed, an error occurs, and the setting of the platen gap becomes unstable.

  In order to prevent the platen gap setting error and instability as described above, when a flag edge is detected, the motor driving torque is reduced to K% of the immediately preceding torque, and the reduced motor driving torque is used. Drive control is performed so that the drive operation is continued for the time τ4.

  As for how much the motor driving torque is to be reduced from the previous torque, that is, how much the value of K% is to be reduced, it is avoided that further driving torque is applied to the motor during the time τ4. In other words, the value is such that the motor naturally decelerates while idling. Therefore, the value of K% may be a constant value or a fluctuation value that fluctuates during time τ4. The reason why the motor driving torque is not completely zero here is that, as will be described later, when the driving operation is continuously performed for two or more flags instead of one flag, the subsequent driving operation is promptly shifted. This is to make it possible.

  While the motor driving torque is reduced and the driving operation is continued for the time τ4 at a torque of K% of the immediately preceding torque, the flag detected in step S2, S4 or S6 is the flag at the position to be stopped, That is, it is determined based on the count value of the counter 101 whether it is a target flag (step S9).

  When the flag detected in step S2, S4 or S6 is not the target flag, that is, when the driving operation is continuously performed for two flags instead of one flag, the process returns to step 1 and the same operation as described above is repeated. The graph showing the motor drive torque command value in this case is the graph of FIG. Note that the graph in FIG. 14B is a graph in the case where the driving operation is continuously performed for two flags.

  If the flag detected in step S2, S4 or S6 is the target flag, after the time τ4 in step 8 has elapsed, the brake is applied to perform the braking control, and the operation of each part of the DC motor 103 and the platen gap adjustment mechanism is stopped. Thus, a series of platen gap adjustment operations is completed (step S10).

  The values of the first, second, and third torques T1, T2, and T3 can be arbitrarily set, and the values of the times τ1, τ2, and τ3 can be arbitrarily set. Therefore, the values of time τ1, τ2, and τ3 do not need to be equal, and can be set appropriately according to the shape of the cam and the magnitude of the load. The first, second, and third torques T1, T2, and T3 are normally set so as to satisfy the condition of T1 <T2 <T3, but this setting is also arbitrary.

  Further, when the different diameter cam 41 is rotated in a direction in which the radius of the different diameter cam 41 at the contact portion with the different diameter cam support shaft 42 is changed from a small radius to a large radius, the different diameter cam 41 is rotated in the opposite direction. Since a large torque is required as compared with the operation, the values of the first, second, and third torques T1, T2, and T3 are changed according to the rotation direction of the different-diameter cam 41, respectively. You may do it.

  In the present embodiment, the three-stage platen gap adjustment is possible by providing three flags. However, by changing the shape of the different diameter cam and providing four or more flags, four or more stages are provided. The platen gap can be adjusted.

  In the above operation, it is preferable to measure the time from the start of the operation until the edge of the flag is detected, and to reflect the measurement result in the subsequent operation. That is, according to the measurement result, the values of the first, second, and third torques T1, T2, and T3 in the subsequent operations, the ratio of the reduced torque to the immediately preceding torque (K%), the driving time τ1, A function of changing τ2, τ3, τ4 may be added to the torque controller 100.

  Further, the flag provided in the present embodiment is a position detection flag, but a speed detection flag may be provided between the position detection flags to further subdivide the time period and motor drive torque control. The speed detection flag in this case is preferably made to be able to identify the type of the flag based on the output of the flag sensor 40, for example, by making the width extremely shorter than the position detection flag.

  As described above, the platen gap adjusting apparatus and the printing apparatus according to the present invention gradually increase the driving torque of the DC motor 103, which is a power source of the platen gap adjusting operation, at predetermined time intervals. If the end portion is detected, the driving torque is not further increased, but the driving torque is reduced at that point, and the driving operation is continued for a predetermined time with the reduced driving torque, and then the braking control is performed. Thus, in a state where the central portion of the target flag is detected by the flag sensor 40, that is, in a state where the different diameter cam support shaft 42 is in contact with the central portion of the different diameter cam 41 having a radius corresponding to the target flag. Since the platen gap adjustment operation is completed, it is possible to adopt a DC motor as a power source, while eliminating the encoder and reducing the manufacturing cost. It is possible to perform an accurate platen gap adjustment over multiple stages.

  An additional effect is that the spreading efficiency of the grease applied to the carriage support shaft 32 is improved by the operation of the platen gap adjustment mechanism.

  In the embodiment described above, the motor to be controlled is described as a DC motor in particular. However, the configuration of the present invention can be applied not only to the DC motor but also to an arbitrary motor.

  The motor driving torque control based on the flag detection in the platen gap adjusting apparatus and the printing apparatus according to the present invention has been described in relation to the operation of the platen gap adjusting mechanism of the printing apparatus. The torque control is not limited to the operation of the platen gap adjustment mechanism of the printing apparatus, and can be applied to a motor control apparatus that drives an arbitrary mechanism. This is a motor control device according to the present invention.

  Therefore, the motor control device according to the present invention corresponds to three or more flags provided for directly or indirectly detecting three or more positions that can be taken by the driving object, and the current position of the driving object. A flag sensor that detects the flag, a counter that counts the number of times the flag is detected by the flag sensor, and gradually increases after the driving of the driving object is started, and decreases when any of the flags is detected. If the flag is not the target flag, a motor driving torque command having a value that gradually increases again is output until the subsequent flag is detected. If the detected flag is the target flag, the motor driving torque is decreased. A torque controller that outputs a stop command after a predetermined time has elapsed, and a motor drive signal is generated based on the command from the torque controller. A motor driver for force, and shall have a, a motor for driving the driven object in accordance with the motor drive signal.

  The platen gap adjusting device and the printing device according to the present invention can be applied to all inkjet printers having a platen gap adjusting mechanism, and further drive an arbitrary mechanism as a motor control device according to the present invention. It can be applied to a motor control device.

1 is a block diagram illustrating a schematic configuration of an inkjet printer. It is the perspective view which showed the structure of the carriage 3 periphery of an inkjet printer. 3 is an explanatory diagram schematically showing the configuration of a linear encoder 11 attached to a carriage 3. FIG. It is the timing chart which showed the waveform of the two output signals of the encoder 11 at the time of CR motor forward rotation and reverse rotation. It is the perspective view which showed the part relevant to paper feed and paper detection. FIG. 3 is a perspective view showing in detail a portion related to paper feeding of the printer. It is the block diagram which showed the structure of DC unit 6 which is a DC motor control apparatus. 4 is a graph showing motor current and motor speed of a DC motor 4 controlled by a DC unit 6. It is a side view which shows schematic structure of the carriage support shaft which comprises a part of platen gap adjustment apparatus, and each part of printing apparatus. FIG. 3 is a side view showing components attached to the carriage support shaft in the platen gap adjusting device and the printing device according to the present invention. It is a graph which shows an example of the flag detection signal waveform by a flag sensor. It is a block diagram which shows the electrical constitution in the platen gap adjustment apparatus and printing apparatus which concern on this invention. 6 is a flowchart showing operations of the platen gap adjusting device and the printing device according to the present invention. It is a graph which shows the motor drive torque command value of the platen gap adjustment apparatus and printing apparatus which concern on this invention.

Explanation of symbols

1 Paper feed motor (PF motor)
2 Paper feed driver 3 Carriage 4 Carriage motor (CR motor)
5 Carriage motor driver (CR motor driver)
6 DC unit 6a Position calculator 6b Subtractor 6c Target speed calculator 6d Speed calculator 6e Subtractor 6f Proportional element 6g Integration element 6h Differentiation element 6j D / A converter 7 Pump motor 8 Pump motor driver 9 Print head (recording head)
10 Head Driver 11 Linear Encoder 12 Code Plate 13 Encoder (Rotary Encoder)
14 Code board 15 for rotary encoder 15 Paper detection sensor 16 CPU
17 Timer IC
18 Host computer 19 Interface unit 20 ASIC
21 PROM
22 RAM
23 EEPROM
25 Platen 30 Pulley 31 Timing belt 32 Carriage guide member (carriage support shaft)
34 Ink cartridge 35 Capping device 36 Pump unit 37 Cap 40 Flag sensor 41 Different diameter cam 42 Different diameter cam support shaft 43 Flag fixing disk member 50 Printing paper (recording paper)
60 Printer 61 Paper feed insertion port 62 Paper discharge port 64 Paper feed roller 65 Paper feed roller 66 Driven roller 67a Large gear 67b Intermediate gear 67c Paper discharge gear 68 Paper discharge roller 69 Driven roller (gagged roller)
83 Smap shaft 84 Platen 87 Small gear 88 Small gear 89 Holder 90 Paper feed tray 100 Torque controller 101 Counter 102 Driver 103 DC motor f1 First flag r1 First radius f2 of different diameter cam Second flag r2 Different diameter cam Second radius f3 third flag r3 third radius T1 of different diameter cam first torque T2 second torque T3 third torque (T1 <T2 <T3)

Claims (30)

A guide member for reciprocating driving of a carriage on which a print head on which a plurality of ink discharge portions for discharging ink are formed is mounted, and is fixed to a carriage support shaft that supports the carriage. A different-diameter cam rotatable about the carriage support shaft as a central axis;
A flag fixing disk member fixed to the carriage support shaft and having a flag fixed to a peripheral portion corresponding to each of the three or more radius radii of the different diameter cam;
By fixing the carriage support shaft vertically below the carriage support shaft, contacting the peripheral edge of the different diameter cam, and setting the carriage support shaft to a height corresponding to the radius of the different diameter cam at the contact portion A different diameter cam support shaft for adjusting a platen gap as a distance between an ink discharge portion forming surface of the print head and a platen that supports a print medium;
The flag corresponding to the radius of the different-diameter cam at the contact portion with the different-diameter cam support shaft, which is disposed around the flag fixing disk member so that the distance from the carriage support shaft is always constant. A flag sensor for detecting
A counter that counts the number of flag detections by the flag sensor;
A value that gradually increases after the start of rotational driving of the different-diameter cam, decreases when any of the flags is detected, and when the detected flag is not a target flag, a value that gradually increases again until the subsequent flag is detected. A torque controller that outputs a motor drive torque command, and outputs a stop command after a lapse of a predetermined time after the motor drive torque is reduced when the detected flag is a target flag;
A motor driver that generates and outputs a motor drive signal based on a command from the torque controller;
A motor that rotationally drives the different-diameter cam according to the motor drive signal;
A platen gap adjusting device comprising:   2. The platen gap according to claim 1, wherein the torque controller outputs a motor drive torque command for gradually increasing the motor drive torque in a plurality of stages after starting the rotation drive of the different diameter cam. 3. Adjustment device.   3. The torque controller according to claim 2, wherein the torque controller outputs a motor drive torque command for gradually increasing the motor drive torque as the whole of the plurality of stages while increasing or decreasing the motor drive torque in each of the plurality of stages. The platen gap adjusting device as described.   When any one of the flags is detected, the torque controller avoids giving further driving torque to the motor according to the value of the immediately preceding motor driving torque, and naturally the motor runs idle. 4. The platen gap adjusting device according to claim 1, wherein the platen gap adjusting device outputs a motor driving torque command for reducing the motor driving torque to such an extent that the motor is decelerated.   5. The platen gap adjustment according to claim 4, wherein the torque controller outputs a braking command to decelerate the motor to such an extent that the motor does not stop immediately before or simultaneously with a decrease in the motor driving torque. apparatus.   The platen gap according to any one of claims 1 to 5, wherein the torque controller changes each value of motor drive torque in a control process in accordance with a rotation direction of the different-diameter cam. Adjustment device.   The torque controller measures the time from the start of rotation driving of the different-diameter cam to the detection of any one of the flags, and the measurement result is used for subsequent rotation drive control of the different-diameter cam. The platen gap adjusting device according to claim 1, wherein the platen gap adjusting device is reflected on the platen gap.   8. A speed detection flag is further provided between each of the position detection flags, and a gradual increase control of the motor driving torque by the torque controller is performed for each further subdivided time period. The platen gap adjusting device according to any one of the above.   9. The platen gap adjusting device according to claim 1, wherein the flag sensor is an optical sensor including a light emitting unit and a light receiving unit facing each other across a passage route of the flag. .   The platen gap adjusting device according to any one of claims 1 to 9, wherein the motor is a DC motor. A platen that supports the print medium;
A print head on which a plurality of ink discharge portions for discharging ink are formed;
A carriage carrying the print head;
Different diameters fixed to a carriage support shaft that supports the carriage as a guide member for reciprocating driving of the carriage, having different three or more radius portions, and rotatable about the carriage support shaft as a central axis With cam,
A flag fixing disk member fixed to the carriage support shaft and having a flag fixed to a peripheral portion corresponding to each of the three or more radius radii of the different diameter cam;
By fixing the carriage support shaft vertically below the carriage support shaft, contacting the peripheral edge of the different diameter cam, and setting the carriage support shaft to a height corresponding to the radius of the different diameter cam at the contact portion A different diameter cam support shaft for adjusting a platen gap as a distance between an ink discharge portion forming surface of the print head and the platen;
The flag corresponding to the radius of the different-diameter cam at the contact portion with the different-diameter cam support shaft, which is disposed around the flag fixing disk member so that the distance from the carriage support shaft is always constant. A flag sensor for detecting
A counter that counts the number of flag detections by the flag sensor;
A value that gradually increases after the start of rotational driving of the different-diameter cam, decreases when any of the flags is detected, and when the detected flag is not a target flag, a value that gradually increases again until the subsequent flag is detected. A torque controller that outputs a motor drive torque command, and outputs a stop command after a lapse of a predetermined time after the motor drive torque is reduced when the detected flag is a target flag;
A motor driver that generates and outputs a motor drive signal based on a command from the torque controller;
A motor that rotationally drives the different-diameter cam according to the motor drive signal;
A printing apparatus comprising:   12. The printing apparatus according to claim 11, wherein the torque controller outputs a motor drive torque command for gradually increasing the motor drive torque in a plurality of stages after the rotation drive of the different diameter cam is started. .   13. The torque controller according to claim 12, wherein the torque controller outputs a motor driving torque command for gradually increasing the motor driving torque as the whole of the plurality of stages while increasing or decreasing the motor driving torque in each of the plurality of stages. The printing apparatus as described.   When any one of the flags is detected, the torque controller avoids giving further driving torque to the motor according to the value of the immediately preceding motor driving torque, and naturally the motor runs idle. The printing apparatus according to claim 11, wherein the printing apparatus outputs a motor driving torque command for reducing the motor driving torque to such an extent that the motor is decelerated.   The printing apparatus according to claim 14, wherein the torque controller outputs a braking command to decelerate the motor to such an extent that the motor does not stop immediately before or simultaneously with a decrease in motor driving torque.   16. The printing apparatus according to claim 11, wherein the torque controller changes each value of the motor driving torque in the control process in accordance with a rotation direction of the different diameter cam. .   The torque controller measures the time from the start of rotation driving of the different-diameter cam to the detection of any one of the flags, and the measurement result is used for subsequent rotation drive control of the different-diameter cam. The printing apparatus according to claim 11, wherein the printing apparatus is reflected on the printing apparatus.   18. A speed detection flag is further provided between the position detection flags, and a gradual increase control of the motor driving torque by the torque controller is performed for each further subdivided time period. The printing apparatus in any one of.   The printing apparatus according to claim 11, wherein the flag sensor is an optical sensor including a light emitting unit and a light receiving unit facing each other across a passage route of the flag.   The printing apparatus according to claim 11, wherein the motor is a DC motor. Three or more flags provided for directly or indirectly detecting three or more possible positions of the drive object;
A flag sensor for detecting the flag corresponding to the current position of the driving object;
A counter that counts the number of flag detections by the flag sensor;
A motor having a value that gradually increases after the driving of the driving object starts, decreases when any of the flags is detected, and increases again until the subsequent flag is detected when the detected flag is not a target flag A torque controller that outputs a drive torque command, and outputs a stop command after a predetermined time has elapsed after reducing the motor drive torque when the detected flag is a target flag;
A motor driver that generates and outputs a motor drive signal based on a command from the torque controller;
A motor for driving the driven object in response to the motor drive signal;
A motor control device comprising:   The motor control device according to claim 21, wherein the torque controller outputs a motor driving torque command for gradually increasing the motor driving torque in a plurality of stages after the driving of the driving object is started.   23. The torque controller according to claim 22, wherein the torque controller outputs a motor drive torque command for gradually increasing the motor drive torque as the whole of the plurality of stages while increasing or decreasing the motor drive torque in each of the plurality of stages. The motor control apparatus described.   When any one of the flags is detected, the torque controller avoids giving further driving torque to the motor according to the value of the immediately preceding motor driving torque, and naturally the motor runs idle. The motor control device according to any one of claims 21 to 23, wherein the motor control device outputs a motor drive torque command for reducing the motor drive torque to such an extent that the motor is decelerated.   25. The motor controller according to claim 24, wherein the torque controller outputs a braking command for decelerating the motor to such an extent that the motor does not stop immediately before or simultaneously with a decrease in motor driving torque. .   The motor controller according to any one of claims 21 to 25, wherein the torque controller changes each value of motor driving torque in a control process according to a driving direction of the driving object. .   The torque controller measures the time from the start of driving of the drive object until any one of the flags is detected, and reflects the measurement result in the subsequent drive control of the drive object. The motor control device according to any one of claims 21 to 26, wherein the motor control device is a motor control device.   28. A speed detection flag is further provided between each of the position detection flags, and the motor drive torque is gradually increased by the torque controller for each subdivided time period. The motor control apparatus in any one of.   The motor control device according to any one of claims 21 to 28, wherein the flag sensor is an optical sensor including a light emitting unit and a light receiving unit facing each other across a passage route of the flag.   30. The motor control device according to claim 21, wherein the motor is a DC motor.

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