JP5953789B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including a reel for winding a recording medium ejected from a printing unit.

  An image forming apparatus including a reel (scroller) for winding a printed recording medium is known (see Patent Document 1). In Patent Document 1, a monitoring task for monitoring the amount of movement of the tension roller by a recording medium is executed. The monitoring task outputs an operation request to operate the reel when the amount of movement of the tension roller reaches a predetermined amount. Accordingly, the reel can be operated according to the tension of the recording medium, and the tension of the recording medium can be adjusted.

JP 2004-107021 A

In Patent Document 1, since it takes a period of time for the reel operation to be completed after the reel operation request is received, the subsequent operation request is output before the reel operation corresponding to the preceding operation request is completed. There was a case. In this case, the monitoring task cannot obtain a response to the subsequent operation request until the operation of the reel corresponding to the previous operation request is completed, and enters a standby state until the response is obtained. Therefore, there is a problem that the monitoring by the monitoring task is not performed until the operation of the reel in response to the preceding operation request is completed, and the image forming apparatus becomes inoperable. In particular, when the monitoring task also monitors other states than the amount of movement of the tension roller, it is impossible to monitor all the states to be monitored by the monitoring task, and the image forming apparatus tends to become inoperable. Further, when there are a plurality of tasks that output reel operation requests, there is a high possibility that a plurality of operation requests are output continuously in a short period of time, and the image forming apparatus tends to become inoperable.
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus that is unlikely to become inoperable even when a plurality of reel operation requests are continuously received.

  In order to solve the above problems, an image forming apparatus of the present invention includes a discharge head that discharges droplets to a recording medium conveyed to a printing unit, a roll that unwinds the recording medium to the printing unit, A reel that winds up the recording medium discharged from the printing unit, a conveyance roller that conveys the recording medium between the roll and the reel so as to pass through the printing unit, and a control unit are provided. The control unit executes a sensor monitoring task for monitoring a plurality of sensors including a tension sensor that detects a tension state of the recording medium between the conveyance roller and the reel. Also, the sensor monitoring task causes the control unit to output an operation request for requesting a reel operation when the tension state becomes a predetermined state. The sensor monitoring task enters a standby state when an operation request is output. Further, the control unit executes a print sequence for controlling the ejection head, the transport roller, the roll, and the reel in cooperation, and performs a print control task for outputting an operation request when the operation timing of the reel comes in the print sequence. Run. The print control task enters a standby state when an operation request is output.

  Further, when an operation request is output, the control unit executes a reel control process for operating the reel, and outputs a response message for releasing the standby state to the task that is the output source of the operation request. Perform a reel task. Then, when an operation request is output during execution of the reel control process, the control unit outputs a response message to the task that has output the operation request without waiting for the reel control process being executed to end. To do.

  In the above configuration, when a subsequent operation request is output during execution of the reel control process, the control unit outputs a response message without waiting for completion of the reel control process being executed. Output to the original task. Therefore, the control unit can continue the task from which the subsequent operation request is output without waiting for the reel control process being executed to end. That is, even when a plurality of operation requests are received in succession, it is possible to prevent the task from which the operation request is output from being in a standby state for a long period of time, thereby preventing the image forming apparatus from becoming inoperable.

  Further, the control unit monitors the operation state of the switch for instructing the operation of the reel by the sensor monitoring task, and outputs an operation request when the operation state becomes a predetermined state, and sets the sensor monitoring task in the standby state. Good. Thereby, even in a configuration including a switch for the user to instruct the operation of the reel, the sensor monitoring task can be prevented from being in a standby state for a long period of time. Further, it is possible to prevent the print control task from being in a standby state for a long period due to the user's operation of the switch.

  Furthermore, when an operation request is output during execution of the reel control processing, the control unit may not execute the reel control processing corresponding to the operation request by the reel task. When a subsequent operation request is output during execution of the reel control process, the timing at which the reel control process corresponding to the subsequent operation request can be executed can be greatly delayed from the output of the subsequent operation request. Therefore, it may be inappropriate to operate the reel in response to the subsequent operation request at the stage of operating the reel in response to the subsequent operation request. This is because the tension state of the recording medium, the switch operation state, and the progress of processing in the printing sequence can change before the reel is operated in response to a subsequent operation request. Accordingly, when an operation request is output during execution of the reel control process, inappropriate reel operation can be prevented by preventing the reel control process corresponding to the operation request from being executed.

  Further, the method of processing a reel operation request as in the present invention can also be applied as a program or method. Moreover, the above apparatuses, programs, and methods may be implemented as a single apparatus, or may be incorporated into an apparatus having multiple functions.

It is a block diagram of a printer. (2A) is a side view of the printer, and (2B) to (2E) are side views of the reel. (3A) to (3C) are sequence diagrams illustrating the operation of the printer.

Here, embodiments of the present invention will be described in the following order.
(1) Printer configuration:
(2) Printer operation:
(3) Modification:

(1) Printer configuration:
FIG. 1 is a block diagram showing a configuration of a printer 1 as an image forming apparatus according to an embodiment of the present invention. The printer 1 includes a control unit 10, an ejection head control circuit 11, a carriage control circuit 12, a transport control circuit 13, and a sensor control circuit 14. The control unit 10 includes a CPU, a RAM, and a ROM (not shown). The CPU loads the control program P recorded in the ROM into the RAM and executes it. With the function of the control program P, the CPU executes processing for controlling the control circuits 11 to 14.

  The ejection head control circuit 11 is a circuit for controlling ejection of ink droplets as droplets in the ejection head HD. In the present embodiment, the ejection head HD includes a plurality of piezo elements that eject ink droplets for each nozzle, and the ejection head control circuit 11 selectively applies a drive voltage to the plurality of piezo elements. Specifically, the ejection head control circuit 11 includes a drive voltage generation circuit that generates a drive voltage, an ejection control circuit that generates ejection data that defines whether or not to eject ink for each nozzle based on print image data, and Is provided. The ejection head control circuit 11 outputs a drive voltage and ejection data to the ejection head HD at each ejection timing at which the nozzle ejects ink based on a command from the control unit 10.

  The carriage control circuit 12 is a circuit for controlling the carriage motor 12a that moves the carriage CR to which the ejection head HD is attached in the main scanning direction. That is, the carriage control circuit 12 supplies a drive current to the carriage motor 12a based on a command from the control unit 10.

  FIG. 2A is a side view schematically illustrating the conveyance system of the printer 1. As shown in FIG. 2A, the carriage CR is provided so as to face the recording surface of the roll paper M as a recording medium conveyed on the platen K. Further, the nozzles of the ejection head HD attached to the carriage CR face the recording surface of the roll paper M. By causing ink droplets ejected from the nozzles of the ejection head HD to land, ink dots can be recorded on the recording surface of the roll paper M conveyed on the platen K. In addition, by ejecting ink droplets from the ejection head HD and performing main scanning of the ejection head HD together with the carriage CR in the main scanning direction (the depth direction of the paper surface), a dot row can be recorded on the roll paper M in the main scanning direction.

  The conveyance control circuit 13 is a circuit that controls the conveyance motor 13a, the roll motor 13b, and the reel motor 13c. That is, the transport control circuit 13 supplies a drive current to the transport motor 13a, the roll motor 13b, and the reel motor 13c based on the command of the control unit 10.

  As shown in FIG. 2A, in the printer 1, a roll RR in which roll paper M is wound around a cylindrical core is set. Note that the roll paper M is wound around the core so that the recording surface on which ink droplet dots are recorded is on the radially outer side of the roll RR and the back surface of the recording surface is on the radially inner side of the roll RR. Note that FIG. 2A is a view seen from the outside in the axial direction of the core of the roll RR. In FIG. 2A, the roll paper M is conveyed onto the platen K so that the recording surface faces up. The roll motor 13b is a motor for rotationally driving the roll RR, and rotationally drives the roll RR around the central axis of the winding core. The roll RR is driven mainly to maintain the tension acting on the roll paper M between the transport roller AR and the roll RR within an appropriate range.

  The transport motor 13a is a motor that drives a transport roller AR for transporting the roll paper M between the roll RR and the reel RE. As shown in FIG. 2A, the transport roller AR is provided so as to face the driven roller PR. The transport roller AR and the driven roller PR are each formed in a cylindrical shape, and the axial direction coincides with the core of the roll RR. The roll paper M is sandwiched between the transport roller AR and the driven roller PR. Then, the roll paper M is transported on the platen K by the transport roller AR being driven to rotate around the central axis. The transport direction of the roll paper M is a sub-scanning direction orthogonal to the main scanning direction of the carriage CR. The conveyance control circuit 13 conveys the roll paper M to the printing unit W by driving the conveyance motor 13a. The printing unit W is an area where ink droplets are ejected onto the roll paper M in the transport path of the roll paper M, and refers to an area facing the ejection head HD in the transport path of the roll paper M. By performing the main scanning of the carriage CR and the conveyance of the roll paper M, dots of ink droplets are recorded in a two-dimensional direction on the recording surface of the roll paper M, and a printed image can be formed. Furthermore, the conveyance control circuit 13 discharges the roll paper M from the printing unit W by driving the conveyance motor 13a.

  The reel RE includes a cylindrical core RE1 and a holding part RE2 that rotatably holds the core RE1. The core RE1 has an axial direction that coincides with the core of the roll RR, the transport roller AR, and the driven roller PR, and is driven to rotate around the central axis. When the winding core RE1 is rotationally driven, the roll paper M discharged from the printing unit W is taken up by the winding core RE1. The reel motor 13c is a motor that rotationally drives the core RE1. As described above, the roll paper M is conveyed between the roll RR and the reel RE via the printing unit W.

  A tension bar RE3 is attached to the holding part RE2. The tension bar RE3 has a rod-shaped arm portion RE3a, and a free end RE3b and a connection end RE3c are provided at both ends in the length direction of the arm portion RE3a. The connection end RE3c is rotatably connected to the holding part RE2, and the tension bar RE3 swings in the rotation direction around the connection end RE3c. The free end RE3b is in sliding contact with the roll paper M being conveyed between the conveyance roller AR and the reel RE1 without the arm portion RE3a coming into contact with the roll RE. When no external force acts on the tension bar RE3, the tension bar RE3 swings so that the free end RE3b is lowered by its own weight. However, as the tension of the roll paper M between the transport roller AR and the reel RE increases, the free end RE3b is pushed upward (clockwise on the paper surface) against the weight of the tension bar RE3.

  2B to 2E are side views of the reel RE. The angle clockwise with respect to the horizontal plane in the length direction of the arm part RE3a is defined as a swing angle θ. As the tension of the roll paper M between the transport roller AR and the reel RE increases, the tension bar RE3 rotates in the clockwise direction on the paper surface and the swing angle θ increases. The swing angle θ at which the arm part RE3a can swing is mechanically limited. A light shielding plate RE3d is attached to the connection end RE3c, and the light shielding plate RE3d swings together with the tension bar RE3. An upper optical sensor S1 and a lower optical sensor S2 are provided as tension sensors in the swing range of the light shielding plate RE3d in the holding unit RE2. The upper photosensor S1 is provided above the lower photosensor S2. Further, the distance between the upper light sensor S1 and the lower light sensor S2 in the rotational movement direction of the light shielding plate RE3d is shorter than the width of the light shielding plate RE3d orthogonal to the length direction of the tension bar RE3.

  The upper light sensor S1 and the lower light sensor S2 do not detect light when blocked by the light blocking plate RE3d, and detect light when not blocked by the light blocking plate RE3d. In the present embodiment, as shown in FIG. 2D, when the lower light sensor S2 is not shielded by the light shielding plate RE3d (black circle) and the upper light sensor S1 is shielded (dotted white circle), the roll paper M is in an appropriate tension state. Suppose that there is. As shown in FIG. 2B, the state in which only the lower light sensor S2 is shielded by the light-shielding plate RE3d that is descending is defined as the roll paper M being in a low tension state. Furthermore, as shown in FIG. 2C, the state in which both the upper light sensor S1 and the lower light sensor S2 are shielded by the light shielding plate RE3d is also the low tension state of the roll paper M. On the other hand, as shown in FIG. 2E, when the upper light sensor S1 and the lower light sensor S2 are not shielded from light, the roll paper M is in a high tension state.

  The sensor control circuit 14 is a circuit for controlling various sensors such as the upper light sensor S1, the lower light sensor S2, the temperature sensor S3, the rotary encoder S4, the paper edge sensor S5, and the switch sensor S6. The temperature sensor S3 measures the temperature of the ejection head HD and the like. The rotary encoder S4 measures the amount of rotation of the roll RR, the transport roller AR, the reel RE, and the like. The paper edge sensor S5 is provided at a detection position A at a predetermined distance from the carriage CR. The paper edge sensor S5 irradiates the roll paper M with inspection light, and detects the presence or absence of the roll paper M at the detection position A based on the state of transmitted light or reflected light of the inspection light on the roll paper M. The switch sensor S6 is a sensor that monitors the operation state of the switch SW for instructing the operation mode of the reel RE. In the present embodiment, an automatic mode or a manual mode is instructed as the operation mode of the reel RE. For example, the switch sensor S6 is a sensor that detects a conduction state, a light reception state, and the like that change according to a mechanical operation state of the switch SW. The automatic mode is a mode in which the reel RE is operated according to the tension state of the roll paper M between the transport roller AR and the reel RE. The manual mode is a mode in which the reel RE is operated so as to forcibly wind the roll paper M in accordance with an operation on the switch SW.

  As shown in FIG. 1, the control program P includes a sensor monitoring unit P1, a print control unit P2, and a reel control unit P3. The control unit 10 can execute multitasking, and executes tasks based on the functions of the sensor monitoring unit P1, the print control unit P2, and the reel control unit P3 in parallel. That is, the control unit 10 always executes a sensor monitoring task based on the function of the sensor monitoring unit P1, a print control task based on the function of the print control unit P2, and a reel control task based on the function of the reel control unit P3. .

  The sensor monitoring unit P1 is a module that causes the control unit 10 to execute a sensor monitoring task for monitoring the plurality of sensors S1 to S6. With this sensor monitoring task, the control unit 10 outputs a reel RE operation request Q triggered by the tension state of the roll paper M between the transport roller AR and the reel RE becoming a predetermined state. Specifically, the control unit 10 monitors the upper light sensor S1 and the lower light sensor S2, and the tension state of the roll paper M is in the low tension state shown in FIG. 2B (S1: light reception, S2: light shielding). Is used as a trigger to output an operation request Q for rotating the winding core RE1 so as to wind up the roll paper M until the proper tension state shown in FIG. 2D (S1: light shielding, S2: light reception) is obtained.

  Further, according to the sensor monitoring task, the control unit 10 causes the tension state of the roll paper M to be in an appropriate tension state (S1: light shielding, S2: light reception) shown in FIG. When rotating, an operation request Q for rotating the winding core RE1 in the direction opposite to the direction of winding the roll paper M is output. That is, when the roll RR is rotated in the direction of winding the roll paper M to increase the tension of the roll paper M, the reel RE is operated so as to maintain an appropriate tension state. When the operation request Q is output by the function of the sensor monitoring unit P1, the control unit 10 sets the sensor monitoring task in a standby state.

  Further, the control unit 10 monitors the operation state of the switch SW for instructing the reel operation by the switch sensor S6 by the sensor monitoring task. Specifically, the control unit 10 outputs an operation request Q for rotationally driving the core RE1 so as to wind up the roll paper M, triggered by the fact that the operation state of the switch SW is in a state instructing the manual mode. Further, the control unit 10 sets the sensor monitoring task in the standby state even when the operation request Q is output according to the operation state of the switch SW by the function of the sensor monitoring unit P1.

  The print control unit P2 executes a print sequence for controlling the carriage CR, the discharge head HD, the transport roller AR, the roll RR, and the reel RE in cooperation with each other, and operates when the operation timing of the reel RE comes in the print sequence. This module outputs a request Q and causes the control unit 10 to execute a print control task. That is, the control unit 10 controls the ejection head control circuit 11, the carriage control circuit 12, and the conveyance control circuit 13 in the printing sequence. When the control unit 10 executes the printing sequence by the printing control task, the main scanning of the carriage CR, the ejection of ink droplets by the ejection head HD, and the conveyance (sub-scanning) of the roll paper M are performed in cooperation. A printed image can be formed on the roll paper M. With this print control task, the control unit 10 outputs an operation request Q triggered by the arrival of the operation timing of the reel RE. Further, the control unit 10 sets the print control task in a standby state when the operation request Q is output by the function of the print control unit P2.

  In the present embodiment, the control unit 10 performs a remaining amount estimation process for the roll paper M in the roll RR as one process of the printing sequence. In this remaining amount estimation process, the control unit 10 rotates the transport roller AR by a predetermined number of rotations while the operations of the carriage CR and the ejection head HD are stopped by the function of the print control unit P2. And the control part 10 acquires the rotation speed of the roll RR rotated following the rotation of the conveyance roller AR by a predetermined rotation speed by the function of the printing control part P2. And by the function of the printing control unit P2, the control unit 10 causes the roll RR to be based on the ratio between the rotation speed of the transport roller AR and the rotation speed of the roll RR and the diameter (known) of the transport roller AR. The diameter (roll diameter) is specified. Further, the control unit 10 estimates the remaining amount of the roll paper M in the roll RR based on the roll diameter of the roll RR by the function of the print control unit P2.

  Here, if slip occurs between the transport roller AR and the roll paper M in the remaining amount estimation process, the roll diameter of the roll RR cannot be measured accurately. On the other hand, when the reel RE winds the roll paper M according to the tension state, the tension of the roll paper M becomes unstable, and slippage may occur between the transport roller AR and the roll paper M. Accordingly, the control unit 10 stops the operation of the reel RE during the period in which the transport roller AR is rotationally driven in the remaining amount estimation process by the function of the print control unit P2. Then, the function of the printing control unit P2 allows the control unit 10 to wind the roll paper M so that the reel RE comes at the operation timing when the period during which the conveyance roller AR is rotationally driven in the remaining amount estimation process has ended. An operation request Q for rotating the lead RE1 is output. Thereby, the slack of the roll paper M generated in the remaining amount estimation process can be eliminated.

  When the operation request Q is output, the reel control unit P3 executes a reel control process for operating the reel RE and outputs a response message G for releasing the standby state from the output source of the operation request Q. This is a module for causing the control unit 10 to execute a reel task to be output to a task. With this reel task, the control unit 10 receives the operation request Q through inter-task communication between the sensor monitoring task and the print control task. When the operation request Q is received by the reel task, in principle, the control unit 10 executes a reel control process in accordance with the operation request Q. The reel control process includes a preparation process and a drive process. In the preparation process, the control unit 10 sets the operation condition of the reel RE by the function of the reel control unit P3. For example, the function of the reel control unit P3 causes the control unit 10 to set, as the operation condition of the reel RE, the direction, speed, period, and the like for rotationally driving the roll motor 13b based on the operation request Q and the like. When the operation condition of the reel RE is set in this preparation process, the control unit 10 executes a driving process for driving the roll motor 13b based on the operation condition by the function of the reel control unit P3. As a result, the roll motor 13b is driven, and the core RE1 of the reel RE is rotationally driven.

  As described above, when the operation request Q is received by the reel task, the control unit 10 executes the reel control process according to the operation request Q in principle. However, when the operation request Q is output during the execution of the preparation process, the control unit 10 does not cause the preparation process corresponding to the operation request Q to be executed by the reel task. In other words, when the reel task performs the preparation process corresponding to the preceding operation request Q, the control unit 10 does not execute the preparation process even if the subsequent operation request Q is received.

  Furthermore, when the control unit 10 accepts the operation request Q by the reel task, it immediately outputs a response message G to the task that is the source of the operation request Q. When the operation request Q is output when the preparation process is not executed, the control unit 10 receives the operation request Q simultaneously with the output of the operation request Q by the reel task, and immediately outputs a response message G of the operation request Q. Output to the original task. On the other hand, if the operation request Q is output during the execution of the preparation process, the control unit 10 accepts the operation request Q simultaneously with the end of the execution of the preparation process being executed, and immediately sends the response message G to the operation message. Output to the task that is the source of request Q. That is, when the preparatory process being executed is completed by the reel task, the control unit 10 outputs the response message G without waiting for the end of the drive process executed following the preparatory process. When the response message G is output, the control unit 10 cancels the standby state of the task to which the response message G is output. As a result, regardless of whether or not the operation request Q was output during the execution of the preparation process, the standby state of the task from which the operation request Q is output can be released early.

(2) Printer operation:
3A to 3C are sequence diagrams of each task executed by the control unit 10 of the printer 1. In FIG. 3A, the control unit 10 detects the operation state of the switch SW in the manual mode for operating the reel RE so as to wind up the roll paper M by the sensor monitoring task, and then the roll paper M is detected as shown in FIG. 2B. An operation example when it is detected that the state is a low tension state (S1: light reception, S2: light shielding) is shown. As shown in FIG. 3A, the control unit 10 starts the preparation process in response to the operation request Q by the reel task, and at the same time, erases (OFF) the valid flag recorded in the predetermined area of the RAM 10b. By the reel task, the control unit 10 records a valid flag in the RAM 10b at the same time as the preparation process is completed. By the reel task, the control unit 10 determines whether or not the valid flag is recorded at the timing when the operation request Q is output. When the valid flag is recorded at the timing when the operation request Q is output, the control unit 10 performs a preparation process according to the operation request Q by the reel task. On the other hand, when the valid flag is not recorded at the timing when the operation request Q is output, the control unit 10 does not execute the preparation process according to the operation request Q by the reel task. Hereinafter, the operation example of FIG. 3A will be described in time series.

  In FIG. 3A, the control unit 10 first outputs a first operation request Q triggered by the detection of the operation state of the switch SW in the manual mode by the sensor monitoring task, and puts the sensor monitoring task into a standby state (hatching). Then, by the reel task, the control unit 10 determines whether or not a valid flag has been recorded at the timing when the operation request Q is output. In the case of FIG. 3A, since the preparation process is not being executed at the timing when the first operation request Q is output, a valid flag is recorded. Therefore, the control unit 10 starts the preparation process in response to the first operation request Q by the reel task, and immediately outputs the response message G to the sensor monitoring task that is the transmission source of the operation request Q. Thereby, the standby state of the sensor monitoring task is released early, and the control unit 10 can resume monitoring of the sensors S1 to S6 early by the sensor monitoring task. Next, the sensor monitoring task causes the control unit 10 to detect that the roll paper M is in a low tension state before the end of the preparation process corresponding to the first operation request Q, and to trigger the second operation request Q. Is output and the sensor monitoring task is set to the standby state.

  Next, the preparation process corresponding to the first operation request Q ends. When the preparation process corresponding to the first operation request Q is completed, the control unit 10 executes the driving process to drive the reel motor 13c by the reel task, and re-records the valid flag that has been erased during the execution of the preparation process. To do. Further, when the preparation process corresponding to the first operation request Q is completed, the control unit 10 receives the operation request Q output during execution of the preparation process by the reel task. Then, by the reel task, the control unit 10 determines whether or not the valid flag is recorded at the timing when the second operation request Q is output. In the case of FIG. 3A, since the preparation process corresponding to the first operation request Q is being executed at the timing when the second operation request Q is output, the valid flag is erased. Accordingly, the control unit 10 immediately outputs the response message G to the sensor monitoring task that is the transmission source of the second operation request Q without executing the preparation process according to the first operation request Q by the reel task. That is, without waiting for the end of the driving process corresponding to the first operation request Q, the response message G is output to the sensor monitoring task that is the transmission source of the second operation request Q. Thereby, the standby state of the sensor monitoring task is released early, and the control unit 10 can resume monitoring of the sensors S1 to S6 early by the sensor monitoring task. Therefore, each process of the printer 1 based on the monitoring results of the sensors S1 to S6 can be continued, and the printer 1 can be prevented from becoming inoperable.

  FIG. 3B shows an operation example when the controller 10 detects the operation state of the switch SW in the manual mode for operating the reel RE so as to wind up the roll paper M twice continuously by the sensor monitoring task. For example, if the user operates the switch SW so that the operation mode of the reel RE is switched from automatic mode → manual mode (first) → automatic mode → manual mode (second time) in a short period of time, The operation state of the switch SW is detected twice in succession. In the case of FIG. 3B, as in the case of FIG. 3A, the response message G is output to the sensor monitoring task that is the transmission source of the second operation request Q immediately after the preparation process corresponding to the first operation request Q is completed. Is done. Thereby, even when the user operates the switch SW continuously, each process of the printer 1 based on the monitoring results of the sensors S1 to S6 can be continued, and the printer 1 can be prevented from becoming inoperable.

  FIG. 3C shows an operation example when the control unit 10 executes the print sequence by the print control task. In this printing sequence, the control unit 10 measures the roll diameter. In the measurement of the roll diameter, the roll paper M is conveyed by a predetermined amount without causing the reel RE to take up the roll paper M in order to suppress the tension fluctuation of the roll paper M. In FIG. 3C, it is assumed that the operation timing T of the reel RE has arrived at the timing when the measurement of the roll diameter is completed by the control unit 10 by the print control task. Then, at the same time as the measurement of the roll diameter is completed, the control unit 10 outputs the first operation request Q for winding the roll paper M loosened in the measurement of the roll diameter by the reel RE. Then, during the execution of the preparation process corresponding to the first operation request Q, the control unit 10 causes the roll paper M to be in a low tension state (S1: light reception, S2: light shielding) as shown in FIG. 2B by the sensor monitoring task. Is detected, and two operation requests Q are output. The sensor monitoring task enters a standby state by the output of the operation request Q twice, but since the response message of the operation request Q is output twice after completion of the preparation process corresponding to the first operation request Q, the sensor monitoring task The standby state can be released early. Therefore, even when the print control task and the sensor monitoring task output a plurality of operation requests Q in succession, it is possible to prevent the printer 1 from becoming inoperable.

(3) Modification:
In the embodiment, the example in which the printer 1 including the image forming apparatus ejects ink droplets is shown, but droplets other than ink droplets may be ejected. Furthermore, the droplets are not limited to those ejected by pressurization due to mechanical changes of the piezo elements, but may be ejected by pressurization due to the generation of bubbles. Further, the recording medium is not limited to the roll paper M but may be a cut sheet or other than paper.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 10 ... Control part, 11 ... Discharge head control circuit, 12 ... Carriage control circuit, 12a ... Carriage motor, 13 ... Conveyance control circuit, 13a ... Conveyance motor, 13b ... Roll motor, 13c ... Reel motor, 14 ... Sensor control circuit, P ... control program, P1 ... sensor monitoring unit, P2 ... print control unit, P3 ... reel control unit, AR ... transport roller, CR ... carriage, RE ... reel, RE1 ... core, RE2 ... holding unit, RE3 ... tension bar, RE3a ... arm part, RE3b ... connection end, RE3c ... free end, RE3d ... light shielding plate, RR ... roll, S1 ... upper light sensor, S2 ... lower light sensor, S3 ... temperature sensor, S4 ... rotary Encoder, S5 ... Paper edge sensor, S6 ... Switch sensor, G ... Response message, HD ... Discharge Head, K ... platen, M ... roll paper, PR ... driven roller, Q ... operation request, W ... printing unit.

Claims (3)

A discharge head that discharges droplets to a recording medium conveyed to a printing unit, a roll that unwinds the recording medium to the printing unit, and a recording medium that is discharged from the printing unit An image forming apparatus comprising: a reel; and a transport roller configured to transport the recording medium so as to pass through the printing unit between the roll and the reel.
An operation that monitors a plurality of sensors including a tension sensor that detects a tension state of the recording medium between the conveyance roller and the reel, and requests the operation of the reel when the tension state becomes a predetermined state. Sensor monitoring task, which is a task that outputs a request and enters standby state,
A print sequence for controlling the discharge head, the transport roller, the roll, and the reel in cooperation is executed, and when the operation timing of the reel comes in the print sequence, the operation request is output and the standby state A print control task that is
A reel task that executes a reel control process for operating the reel when the operation request is output, and outputs a response message for releasing the standby state to a task that outputs the operation request; , and a control unit for executing,
The reel control process includes a preparation process and a driving process that operates after the preparation process,
The reel task,
When the operation request is input before executing the preparation process, the preparation process is executed, and the response message is output to the task that is the output source of the operation request,
When the operation request is input during execution of the preparation process , when the preparation process ends, the response message is output to the task that is the output source of the operation request.
Image forming apparatus. According to the sensor monitoring task, the control unit monitors an operation state of a switch for instructing the operation of the reel, and outputs the operation request when the operation state becomes a predetermined state to execute the sensor monitoring task. The standby state,
The image forming apparatus according to claim 1. When the operation request is output during execution of the reel control process, the control unit does not execute the reel control process according to the operation request by the reel task.
The image forming apparatus according to claim 1.

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