JP2015123700A - Interruption control device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably control a stepping motor by monitoring the completion of specific interruption processing.SOLUTION: An interruption processing control device includes: a control section for executing interruption control processing of a stepping motor; interruption sources for generating interruption requests; an interruption time monitoring counter for outputting a count-up signal when time after the generation of the interruption request of a specific interruption source of the interruption sources passes a time limit; a motor state information register for storing and outputting motor state information showing the state of the stepping motor; and an information addition section for adding additional information to the motor state information output by the motor state information register when the count-up signal is output. When the interruption request of the specific interruption source is generated, the interruption control processing is started and the motor state information is read. When the additional information is added to the motor state information, the interruption control processing is stopped in the middle.

Description

  The present invention relates to an interrupt control device and an image forming apparatus.

  2. Description of the Related Art Conventionally, in image forming apparatuses such as printers, copying machines, and facsimile machines, stepping motors are used for transporting a medium such as printing paper and driving a head such as a print head. The rotation of the stepping motor is controlled by switching the current supplied to the stepping motor, and the timing for outputting the phase switching signal for switching the current is managed by a timer.

  For example, a predetermined time from when the phase switching signal is output until the next phase switching signal is output, that is, the phase switching time is counted by a timer. When the phase switching time is counted up, the phase switching signal is output, and counting of the phase switching time until the next phase switching signal is output is started. At the same time, interrupt processing is executed, and the phase switching time set at the next interrupt timing is set by the program. In the control of the stepping motor, it is important to execute the interrupt process for phase switching at a time interval related to the speed of the stepping motor and complete the interrupt process within the time interval (see, for example, Patent Document 1). .)

JP 2008-160900 A

  However, in the conventional image forming apparatus, when a process having a higher priority than an interrupt process that is periodically executed, such as a phase switching interrupt process, is being executed, the start of execution of the interrupt process waits. It will be. When the execution start is made to wait, the completion timing of the interrupt process is delayed. If the delay is large, the next interrupt timing is not in time. As described above, if the interrupt process is not completed by the next interrupt timing, the stepping motor cannot be regularly controlled, and an abnormal state occurs.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an interrupt control device and an image forming apparatus that can stably control a stepping motor by solving the conventional problems and monitoring the completion of specific interrupt processing. And

  Therefore, in the interrupt control device of the present invention, a control unit that executes the interrupt control process of the stepping motor, an interrupt source that generates an interrupt request, and an interrupt request of a specific interrupt source among the interrupt sources are generated. An interrupt time monitoring counter that outputs a count-up signal when the time after the limit has elapsed, a motor status information register that stores and outputs motor status information indicating the status of the stepping motor, and the count-up signal is output An information adding unit for adding additional information to the motor status information output from the motor status information register, and the control unit performs the interrupt control process when an interrupt request for the specific interrupt source is generated. Start, read the motor status information, and add the additional information to the motor status information. If you are ends prematurely said interrupt control process.

  According to the present invention, the interrupt control device monitors completion of specific interrupt processing. Thereby, the stepping motor can be stably controlled.

1 is a block diagram illustrating a configuration of an image forming apparatus according to a first embodiment of the present invention. It is a block diagram which shows the structure of the principal part of the control unit in the 1st Embodiment of this invention. It is a time chart which shows the time monitoring control with respect to the motor control interruption process in the 1st Embodiment of this invention. It is a flowchart which shows the operation | movement of the motor control interruption process in the 1st Embodiment of this invention. It is a block diagram which shows the structure of the principal part of the control unit in the 2nd Embodiment of this invention. It is a time chart which shows the time monitoring control with respect to the motor control interruption process in the 2nd Embodiment of this invention. It is a flowchart which shows the operation | movement of the motor control interruption process in the 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of the image forming apparatus according to the first embodiment of the present invention.

  In the figure, reference numeral 10 denotes an image forming apparatus, for example, a multi-function printer (MFP) having the functions of a printer, a facsimile machine, a copier, a printer, a facsimile machine, and a copier. Any type of image forming apparatus may be used as long as it can form an image on a medium such as printing paper by using various image forming systems such as a photographic system and a thermal transfer system. In the present embodiment, the case where the image forming apparatus 10 is a thermal transfer printer will be described.

  The image forming apparatus 10 is communicably connected to a host apparatus 11 serving as a host device via a communication line such as a network (not shown) or a USB (Universal Serial Bus) line. The host device 11 may be any type of device as long as it can create a print command including print data and transmit the print command to the image forming apparatus 10, for example, a server, a PDA (Personal Digital Assistant). ), Electronic notebook, game machine, mobile phone, etc., but here, for example, arithmetic means such as CPU and MPU, storage means such as magnetic disk and semiconductor memory, input means such as keyboard, mouse and touch panel A personal computer having a display means such as a CRT or a liquid crystal display, a communication interface, and the like will be described.

  The image forming apparatus 10 includes a control unit 12 as a control device that controls the operation of each unit of the image forming apparatus 10, a ROM 13 as a storage unit, a RAM 14 as a storage unit, and a power supply voltage as a power supply voltage dividing unit. A voltage dividing circuit 15, a temperature sensor 16 as temperature detecting means, an operation panel 17 as a user interface, a thermal head 18 as a thermal transfer head as an image forming unit, a motor driver circuit 19 as a motor driving unit, and a medium as a stepping motor A conveyance motor 20 is included.

  Here, the ROM 13 stores a printer control program as a program for controlling the image forming apparatus 10. The RAM 14 stores various data necessary for controlling the printer control program and the image forming apparatus 10. Further, the power supply voltage dividing circuit 15 confirms whether or not the voltage of the power supply of the image forming apparatus 10 exceeds the specified range. Further, the temperature sensor 16 detects the temperature of the medium transport motor 20 that changes due to heat generation, converts the temperature into an analog signal, and outputs the analog signal.

  Further, the operation panel 17 includes a switch for a user of the image forming apparatus 10 to perform an operation, a display panel for confirming the state of the image forming apparatus 10 and the like. Further, the thermal head 18 forms an image on a medium by performing thermal transfer printing. Further, the motor driver circuit 19 drives the medium transport motor 20. Further, the medium transport motor 20 is a drive source for driving a roller, a belt, or the like that transports the medium.

  The control unit 12 includes a central control unit 21 as a control unit including a memory control unit 22 and a CPU 23, an A / D converter 24, a panel I / F control unit 25, an interrupt control unit 26, a print control unit 27, A motor control unit 28, a timer 29, and a host I / F control unit 30 are provided. The memory control unit 22, CPU 23, A / D converter 24, panel I / F control unit 25, interrupt control unit 26, print control unit 27, motor control unit 28, timer 29, and host I / F control unit 30 are Are connected to each other via an internal bus 31 as a communication line.

  Here, the central control unit 21 executes an interrupt control process of the medium transport motor 20 as a stepping motor. The memory control unit 22 is communicably connected to the ROM 13 and the RAM 14, and reads (writes) and writes (writes) the ROM 13 and the RAM 14. The CPU 23 is a calculation unit, and executes a printer control program read via the memory control unit 22. Further, the A / D converter 24 converts an analog signal output from the power supply voltage dividing circuit 15 and the temperature sensor 16 into a digital signal. Further, the panel I / F control unit 25 accesses the operation panel 17 to read a switch of the operation panel 17 and to display the display panel.

  The host I / F control unit 30 is connected to the host device 11 and receives print data and transmits / receives control data. The timer 29 is a time measuring means and functions as a trigger for periodically generating processing such as control of the operation panel 17. Further, the motor control unit 28 performs signal control for driving the medium transport motor 20. Specifically, the phase switching signal 37a for switching the current supplied to the medium transport motor 20 that is a stepping motor, and the PWM (Pulse Width Modulation) control corresponding to the current value of each phase are turned on. A current control signal 37 b for determining the duty time is output to the motor driver circuit 19 that drives the medium transport motor 20.

  The print control unit 27 performs signal control for driving the thermal head 18. Further, the interrupt control unit 26 monitors the first to third interrupt request signals 32a to 32c output from the motor control unit 28, the timer 29, and the host I / F control unit 30 to confirm that an interrupt request has occurred. When detected, the CPU 23 is notified.

  The first interrupt request signal 32a as an interrupt request signal output from the motor control unit 28 to the interrupt control unit 26 is used to notify the CPU 23 of the phase switching timing of the medium transport motor 20 which is a stepping motor. The The second interrupt request signal 32b as an interrupt request signal output from the timer 29 to the interrupt control unit 26 is used to notify the CPU 23 at regular intervals in order to periodically monitor the operation panel 17. used. Further, the third interrupt request signal 32c as an interrupt request signal output from the host I / F control unit 30 to the interrupt control unit 26 is used to promptly execute processing of print data from the host device 11. Used to notify the CPU 23 when reception of print data from the apparatus 11 is detected.

  Next, the configuration of the control unit 12 will be described in detail.

  FIG. 2 is a block diagram showing a configuration of a main part of the control unit according to the first embodiment of the present invention.

  Control for interrupt processing in the present embodiment is mainly executed by the central control unit 21, the A / D converter 24, the interrupt control unit 26, and the motor control unit 28. The interrupt control unit 26 includes an interrupt request register 33, an interrupt time monitoring counter 34, and an interrupt monitoring time setting register 35, as shown in the figure.

  The interrupt request register 33 includes a first interrupt request signal 32a from the motor control unit 28 as a specific interrupt source that generates an interrupt request, a timer 29 and a host I / O as other interrupt sources that generate an interrupt request. The second interrupt request signal 32b and the third interrupt request signal 32c from the F control unit 30 are received, and the CPU 23 is notified that an interrupt request has occurred. The interrupt request register 33 also notifies the interrupt time monitoring counter 34 that an interrupt request has occurred according to the setting.

  The interrupt time monitoring counter 34 outputs a count-up signal when a time limit has elapsed since the occurrence of an interrupt request for a specific interrupt source among the interrupt sources. Specifically, the count is started upon receiving a notification from the interrupt request register 33 that an interrupt request of a specific interrupt source has occurred. This is because the time from when the interrupt request is generated is counted.

  In the present embodiment, when the interrupt request register 33 detects that the first interrupt request signal 32a has become high level, it notifies the interrupt time monitoring counter 34 that an interrupt request has occurred. However, even if it is detected that the second interrupt request signal 32b or the third interrupt request signal 32c has become high level, the interrupt time monitoring counter 34 is not notified that an interrupt request has occurred.

  In general, in the control of a stepping motor, the control must be surely executed at every interrupt generation timing. Therefore, the interrupt time monitoring counter 34 needs to monitor only the interrupt request from the motor control unit 28. However, regarding the interrupt request from the timer 29 or the host I / F control unit 30, since the fatal failure does not occur even if the start of the interrupt processing is delayed, the interrupt time monitoring counter 34 does not need to be monitored.

  The interrupt monitoring time setting register 35 is a register for storing the time counted by the interrupt time monitoring counter 34. The counting time is the time limit, and is set in the interrupt time monitoring counter 34 by the central control unit 21 in advance. Then, at the timing when the counting time has elapsed, the interrupt time monitoring counter 34 outputs a time monitoring count-up signal 36 as a count-up signal. Specifically, the time monitoring count up signal 36 is set to the high level and output to the A / D converter 24.

  The A / D converter 24 includes a first register 41 and a second register 42 as registers, a selector circuit 43 as a selector unit, an information adding circuit 44 as an information adding unit, a decoding circuit 45 as a decoding unit, and an A / D. A conversion unit 46 is provided.

  The first register 41 stores a value obtained by converting the voltage value of the analog signal input from the power supply voltage divider circuit 15 through the first channel CH1 into a digital value by the A / D converter 46. The second register 42 functions as a motor status information register that stores and outputs motor status information indicating the status of the stepping motor. Specifically, a value obtained by converting the voltage value of the analog signal input from the temperature sensor 16 through the second channel CH2 into a digital value by the A / D converter 46 is stored.

  Further, when a read request of the register is generated from the central control unit 21, the decode circuit 45 determines the first register 41 and the first register 41 based on the value of the register address requested by the address data 49 output from the central control unit 21. A corresponding register is selected from the second register 42. Specifically, the decode circuit 45 determines whether the register corresponding to the address data 49 output from the central control unit 21 is the first register 41 or the second register 42, and sends it to the selector circuit 43. In response to this, a register select signal 51 is output.

  Then, the selector circuit 43 outputs the value stored in the register selected by the decoding circuit 45 to the information adding circuit 44. Specifically, the selector circuit 43 selects the register data designated by the register select signal 51 from the input data of the plurality of registers, and outputs it as the register data 47 to the information adding circuit 44.

  When the time monitoring count up signal 36 is output, the information adding circuit 44 adds additional information to the motor state information output from the second register 42. Specifically, the value of the time monitoring count-up signal 36 input from the interrupt time monitoring counter 34 is added as additional information to the MSB (Most Significant Bit: most significant bit) of the register read data 48 output to the internal bus 31. Append. Then, register data 47 input from the selector circuit 43 is set in a portion other than the MSB of the register read data 48.

  In the present embodiment, the case where the value of the time monitoring count up signal 36 is added to the MSB of the register read data 48 has been described. However, it can be recognized that the value of the time monitoring count up signal 36 is added. If possible, the part to which the value of the time monitoring count-up signal 36 is added is not necessarily limited to the MSB, and may be, for example, an LSB (Least Significant Bit), and any part. It may be.

  Next, the operation of the image forming apparatus 10 having the above configuration will be described. Here, the operation of a motor control interrupt process, which is an interrupt control process for controlling the medium transport motor 20, will be described. First, time monitoring control for motor control interrupt processing will be described.

  FIG. 3 is a time chart showing the time monitoring control for the motor control interrupt processing in the first embodiment of the present invention.

  If the medium transport motor 20 that is a stepping motor is rotating, a motor control interrupt process is generated at each phase switching timing.

  In the present embodiment, when the interrupt request register 33 detects that the first interrupt request signal 32a, which is an interrupt request signal from the motor control unit 28 as a specific interrupt source, has become high level, the interrupt time monitoring counter 34 is notified that an interrupt request has occurred. However, even if it is detected that the second interrupt request signal 32b and the third interrupt request signal 32c, which are interrupt request signals from the timer 29 and the host I / F control unit 30 as other interrupt sources, become high level. The interrupt time monitoring counter 34 is not notified that an interrupt request has occurred.

  If the medium transport motor 20 that is the stepping motor is rotating, the motor control unit 28 switches the phase switching signal for switching the current supplied to the medium transport motor 20 that is the stepping motor, as shown in the figure. 37a is output and the first interrupt request signal 32a is output. The first interrupt request signal 32a is asserted and becomes high level at the timing when the phase switching signal 37a becomes high level, that is, at each phase switching timing. When the first interrupt request signal 32a becomes high level, the interrupt request register 33 notifies the interrupt time monitoring counter 34 that an interrupt request has occurred. Then, the interrupt time monitoring counter 34 loads the value set in the interrupt monitoring time setting register 35, that is, the time limit, and starts the counting operation. The value set in the interrupt monitoring time setting register 35 is set to a time shorter than the interval of the phase switching timing, that is, the interrupt generation interval.

  When the count value of the interrupt time monitoring counter 34 becomes 0, the count is incremented, and the interrupt time monitoring counter 34 sets the time monitoring count up signal 36 to the high level and outputs it to the A / D converter 24. Then, the information addition circuit 44 adds the value of the time monitoring count up signal 36 to the MSB of the register read data 48. As a result, the MSB value of the register read data 48 output from the A / D converter 24 becomes 1.

  Next, motor control interrupt processing executed by the central control unit 21 will be described.

  FIG. 4 is a flowchart showing the operation of the motor control interrupt process in the first embodiment of the present invention.

  When the first interrupt request signal 32a, which is an interrupt request signal from the motor control unit 28 as a specific interrupt source, becomes high level and an interrupt request is generated, the central control unit 21 starts motor control interrupt processing, In order to continue the phase switching control of the transport motor 20, the next phase switching time is set in the motor control unit 28. If a correction value for the rotation speed of the medium transport motor 20 is calculated in the previous motor control interruption process, the correction value is applied.

  Subsequently, the central control unit 21 reads the second register 42 of the A / D converter 24 in order to grasp the temperature of the medium transport motor 20. Specifically, the register read data 48 in which the value of the time monitoring count up signal 36 is added to the MSB is read.

  Subsequently, the central control unit 21 determines whether or not the MSB = 1 of the register read data 48. That is, the MSB value of the read register read data 48 is confirmed, and it is determined whether MSB = 1 or MSB = 0.

  When the MSB = 1, it can be determined that the time from the occurrence of the interrupt request has passed the time limit, that is, exceeded, so the central control unit 21 keeps the interrupt generation interval. The motor control interrupt process is immediately terminated without executing the subsequent operations.

  As a cause of the occurrence of the state in which the time limit is exceeded, for example, it is conceivable that another process having a higher priority than the motor control interrupt process is executed at the time when the interrupt request is generated. If the central control unit 21 is executing another process, the start of the motor control interrupt process is awaited. Even if the process is started after waiting for a long time, the next motor control interrupt occurs before the completion of the execution of all the process steps of the motor control interrupt process. For this reason, if the time from the generation of the interrupt request exceeds the time limit, it is necessary to immediately terminate the motor control interrupt process without executing the unexecuted process step.

  Here, the unexecuted processing step is processing related to temperature information of the medium transport motor 20. The process related to the temperature information is a process of recognizing the temperature information of the medium transport motor 20 and performing feedback to the motor control unit 28. However, the interval of the phase switching timing of the medium transport motor 20 which is a stepping motor, that is, the interrupt generation interval is a short time of about several hundreds [μs], and the temperature of the medium transport motor 20 rapidly increases in such a short time. Does not change. Therefore, even if the process related to the temperature information cannot be executed in the current motor control interrupt process, if it can be executed in the next motor control interrupt process, a serious problem occurs in the control of the medium transport motor 20. Never do.

  If the MSB of the register read data 48 is determined to be 1 MSB = 0, the central control unit 21 converts the value of the A / D converter 24 into the motor temperature. Specifically, the value input from the temperature sensor 16 included in the data obtained by reading the register read data 48 is converted into the temperature of the medium transport motor 20.

  Subsequently, the central control unit 21 determines whether or not the motor temperature is lower than the specified temperature. Specifically, it is determined whether or not the temperature of the medium transport motor 20 is lower than a preset specified temperature.

  When the motor temperature is not lower than the specified temperature, that is, when the motor temperature is equal to or higher than the specified temperature, the central control unit 21 calculates a motor control correction value corresponding to the current temperature, and ends the motor control interrupt process. Specifically, in order to lower the temperature of the medium transport motor 20, a correction value for decreasing the rotation speed of the medium transport motor 20 is calculated and output to the motor driver circuit 19 that drives the medium transport motor 20. The correction value of the current control signal 37b is calculated, and the motor control interrupt process is terminated. The correction value is applied in the next motor control interruption process.

  If it is determined whether the motor temperature is lower than the specified temperature, that is, if the temperature of the medium transport motor 20 is lower than a predetermined temperature, it is not necessary to lower the temperature of the medium transport motor 20. Therefore, the central control unit 21 immediately ends the motor control interrupt process.

Next, a flowchart will be described.
Step S1: The phase switching time of the medium transport motor 20 is set.
Step S2: Read the second register 42 of the A / D converter 24.
Step S3: It is determined whether or not the MSB of the register read data 48 = 1. If the MSB of the register read data 48 is 1, the process ends. If the MSB of the register read data 48 is not 1, the process proceeds to step S4.
Step S4: The value of the A / D converter 24 is converted into the temperature of the medium transport motor 20.
Step S5: It is determined whether or not the temperature of the medium transport motor 20 is lower than a specified temperature. If the temperature of the medium transport motor 20 is lower than the specified temperature, the process ends. If the temperature of the medium transport motor 20 is not lower than the specified temperature, the process proceeds to step S6.
Step S6: A motor control correction value corresponding to the current temperature is calculated, and the process ends.

  As described above, in the present embodiment, the central control unit 21 starts the motor interrupt control process when an interrupt request from the motor control unit 28 as a specific interrupt source is generated, and the second register 42 as the motor status information. The register read data 48 is read, and if additional information is added to the register read data 48, the motor interrupt control process is terminated halfway. If no additional information is added to the register read data 48, the motor interrupt control process is terminated after executing a feedback process based on the motor temperature as the motor status information.

  Here, when the interrupt request register 33 detects that the interrupt request signal from the motor control unit 28 as a specific interrupt source has become high level, the interrupt request register 33 notifies the interrupt time monitoring counter 34 that an interrupt request has occurred. However, even if it is detected that the interrupt request signal from another interrupt source has become high level, the interrupt time monitoring counter 34 is not notified that the interrupt request has occurred. Then, when notified that an interrupt request has occurred, the interrupt time monitoring counter 34 adds information indicating that the interrupt request has occurred to a specific portion of the register read data 48.

  Thus, information indicating that an interrupt request has been generated can be read by a normal register read cycle in which the register read data 48 is read, and the phase switching timing of the medium transport motor 20 that is a stepping motor that is generated periodically. The processing content can be changed, for example, the motor control interrupt processing is terminated in the middle so as not to affect the interval.

  Therefore, the medium transport motor 20 can be stably controlled without affecting the phase switching timing of the medium transport motor 20 that is a stepping motor.

  In other words, the value of the register read data 48 that has been read by the information adding circuit 44 that adds to the specific bit of the register read data 48 that is normally read in the interrupt processing that the interrupt processing time has exceeded the specified time limit. It has a function that can determine the status of interrupt processing time. As described above, since the progress of the interrupt processing time can be recognized by the read cycle of the register read data 48, when the time limit has elapsed, the motor control interrupt processing can be terminated halfway. . By recognizing the passage of the time limit when executing the motor control interrupt process, it is possible to determine whether or not the motor control interrupt process can be continued. By determining the continuation or termination of the process in the regularly generated motor control interrupt process, the motor control interrupt process can be terminated without exceeding the next interrupt generation timing.

  Next, a second embodiment of the present invention will be described. In addition, about what has the same structure as 1st Embodiment, the description is abbreviate | omitted by providing the same code | symbol. The description of the same operation and the same effect as those of the first embodiment is also omitted.

  FIG. 5 is a block diagram showing the configuration of the main part of the control unit according to the second embodiment of the present invention.

  In this embodiment, the A / D converter 24 includes a read number counter 52 in addition to the first register 41, the second register 42, the selector circuit 43, the information addition circuit 44, the decoding circuit 45, and the A / D conversion unit 46. Is provided.

  The read count counter 52 functions as an elapsed count counter that counts the number of times that the time limit has elapsed since the occurrence of an interrupt request of a specific interrupt source in the most recent past and outputs the elapsed count. Specifically, the time monitor count-up signal 36 output from the interrupt time monitor counter 34 and the register select signal 51 output from the decode circuit 45 are monitored. Based on the register select signal 51, it is possible to recognize whether the first register 41 and the second register 42 as registers are being accessed. Further, based on the time monitoring count-up signal 36, it can be recognized whether or not the time from the generation of the interrupt request has passed the time limit.

  In other words, the read number counter 52 can recognize whether or not the corresponding register has been accessed under the condition that the time from the occurrence of the interrupt request has exceeded the time limit. Counts the number of times. When a continuous access to the register is detected, the read number counter 52 outputs a continuous access detection signal 53 to the information adding circuit 44.

  In addition to the function of adding the value of the time monitoring count up signal 36 input from the interrupt time monitoring counter 34 to the MSB of the register read data 48 output to the internal bus 31, the information adding circuit 44 in the present embodiment includes: It has a function of adding the information of the continuous access detection signal 53 output from the read counter 52 to the lower 1 bit from the MSB. Therefore, by reading the most significant 2 bits of the register read data 48, it is possible to obtain information related to the register read cycle in the motor control interrupt process. Further, register data 47 input from the selector circuit 43 is set in a portion other than the most significant 2 bits of the register read data 48.

  For example, when reading the second register 42, the decode circuit 45 determines the corresponding register based on the value of the register address requested by the address data 49 output from the central control unit 21, and sends it to the selector circuit 43. In response to this, a register select signal 51 is output. Then, the selector circuit 43 to which the register select signal 51 is input selects the register data determined by the decode circuit 45 from the input data of the plurality of registers, and the register data 47 is sent to the information adding circuit 44. Output. Then, the information adding circuit 44 sets the input register data 47 as it is in the portion other than the most significant 2 bits of the register read data 48, and registers the values of the time monitoring count-up signal 36 and the continuous access detection signal 53 as register read. Set to the most significant 2 bits of data 48.

  In this embodiment, the case where the values of the time monitoring count-up signal 36 and the continuous access detection signal 53 are added to the most significant 2 bits of the register read data 48 has been described. If it can be recognized that the value of the signal 53 is added, the portion to which the values of the time monitoring count up signal 36 and the continuous access detection signal 53 are added is not necessarily limited to the most significant 2 bits. Instead, it can be any part.

  Since the configuration of other points is the same as that of the first embodiment, description thereof is omitted.

  Next, the operation of the image forming apparatus 10 in the present embodiment will be described. Here, the operation of a motor control interrupt process that is an interrupt process for controlling the medium transport motor 20 will be described. First, time monitoring control for motor control interrupt processing will be described.

  FIG. 6 is a time chart showing time monitoring control for motor control interrupt processing in the second embodiment of the present invention.

  As in the first embodiment, if the medium transport motor 20 that is a stepping motor is rotating, a motor control interrupt process is generated at each phase switching timing.

  As described above, the read counter 52 uses the time monitoring count-up signal 36 and the register select signal 51 as input signals. If the register select signal 51 is at a high level when the time monitoring count-up signal 36 is at a high level, the read number counter 52 increments the value. This is because the read count counter 52 is a counter for detecting that the corresponding register is read at the timing when the time from the occurrence of the interrupt request has passed the time limit.

  Further, when the register select signal 51 becomes high level when the time monitoring count-up signal 36 is low level, the corresponding register has been read at a timing when the time limit from the occurrence of the interrupt request does not elapse. Therefore, the read number counter 52 does not increment the value.

  In this embodiment, the read number counter 52 as the elapsed number counter is the time from when an interrupt request of a specific interrupt source is generated in the most recent (for example, twice) interrupt control processing in the past. Counts the number of times that the time limit has elapsed and outputs the number of elapsed times. Specifically, when the corresponding register is read at the timing when the time from the occurrence of the interrupt request has passed the time limit for two consecutive times, that is, the value of the read count counter 52 becomes 2. In this case, the continuous access detection signal 53 output from the read number counter 52 becomes high level. When the continuous access detection signal 53 becomes high level, the value of the most significant 2 bits of the register read data 48 changes to “11” or “01”. The lower bits of the most significant 2 bits indicate the state of the continuous access detection signal 53.

  As described above, when the corresponding register is read twice at the timing when the time from the generation of the interrupt request has passed the time limit, the value of the most significant 2 bits of the register read data 48 changes. Therefore, the central control unit 21 can recognize continuous access.

  The operation of other points in the time monitoring control with respect to the motor control interrupt process is the same as that in the first embodiment, and thus the description thereof is omitted.

  Next, motor control interrupt processing executed by the central control unit 21 will be described.

  FIG. 7 is a flowchart showing the operation of the motor control interrupt process in the second embodiment of the present invention.

  When the first interrupt request signal 32a, which is an interrupt request signal from the motor control unit 28 as a specific interrupt source, becomes high level and an interrupt request is generated, the central control unit 21 starts the motor control interrupt process, Determine whether there is a down instruction. The state in which there is a speed down instruction is a state in which the speed down instruction flag for reducing the rotation speed of the medium transport motor 20 is set to ON in the previous motor control interruption process.

  When there is no instruction to reduce the speed, the central control unit 21 sets the next phase switching time in the motor control unit 28 in order to continue the phase switching control of the medium transport motor 20. If a correction value for the rotation speed of the medium transport motor 20 is calculated in the previous motor control interruption process, the correction value is applied.

  When there is an instruction to reduce the speed, the central control unit 21 sets the next phase switching time in the motor control unit 28 in order to reduce the rotation speed of the medium transport motor 20. That is, deceleration setting is performed. The purpose of this is to ensure a sufficient time to execute all the processing steps without ending the motor control interruption process in the middle. However, since a sudden decrease in the rotational speed causes the medium transport motor 20 to step out, stepwise deceleration may be necessary.

  Subsequently, the central control unit 21 reads the second register 42 of the A / D converter 24 in order to grasp the temperature of the medium transport motor 20. Specifically, the register read data 48 in which the value of the time monitoring count up signal 36 is added to the MSB is read.

  Subsequently, the central control unit 21 determines the value of the most significant 2 bits of the register read data 48. That is, the value of the most significant 2 bits of the read register read data 48 is checked to determine whether it is “00”, “01”, “11”, or “10”. .

  If the value of the most significant 2 bits of the register read data 48 is “00”, it can be determined that the time from the occurrence of the interrupt request has not passed the time limit, that is, has not exceeded. The central control unit 21 sets temperature information. Specifically, the value input from the temperature sensor 16 included in the data obtained by reading the register read data 48 of the A / D converter 24 is converted into the temperature of the medium transport motor 20.

  Also, when the value of the most significant 2 bits of the register read data 48 is “01”, it is determined that the time from the generation of the interrupt request has not passed the time limit as in the case of “00”. Therefore, the central control unit 21 sets temperature information.

  Subsequently, the central control unit 21 determines whether or not the motor temperature is lower than the specified temperature. Specifically, it is determined whether or not the temperature of the medium transport motor 20 is lower than a preset specified temperature.

  When the motor temperature is not lower than the specified temperature, that is, when the motor temperature is equal to or higher than the specified temperature, the central control unit 21 calculates a motor control correction value corresponding to the current temperature, and ends the motor control interrupt process. Specifically, in order to lower the temperature of the medium transport motor 20, a correction value for decreasing the rotation speed of the medium transport motor 20 is calculated and output to the motor driver circuit 19 that drives the medium transport motor 20. The correction value of the current control signal 37b is calculated, and the motor control interrupt process is terminated. The correction value is applied in the next motor control interruption process.

  If it is determined whether the motor temperature is lower than the specified temperature, that is, if the temperature of the medium transport motor 20 is lower than a predetermined temperature, it is not necessary to lower the temperature of the medium transport motor 20. Therefore, the central control unit 21 immediately ends the motor control interrupt process.

  On the other hand, when the value of the most significant 2 bits of the register read data 48 is determined to be “11”, the register of the corresponding register at the timing when the time limit from the occurrence of the interrupt request has passed the time limit twice consecutively. Since the read has been performed and the time from the occurrence of the interrupt request has exceeded the time limit, control must be performed so that feedback processing from the temperature information can be executed at the next motor control interrupt. I must. Therefore, the central control unit 21 turns on the speed down instruction flag. Thereby, the deceleration setting is performed in the next motor control interruption process. As described above, when the state where the register read is executed after the time limit is exceeded is detected, control for completing the processing can be performed.

  Further, when the value of the most significant 2 bits of the register read data 48 is determined to be “10”, it can be determined that the time from the generation of the interrupt request has passed the limit time, that is, exceeded. Therefore, the central control unit 21 immediately ends the motor control interrupt process without executing the subsequent operations in order to keep the interrupt generation interval. As described in the first embodiment, even if the process related to the temperature information cannot be executed in the current motor control interrupt process, if it can be executed in the next motor control interrupt process, the medium is conveyed. No serious problems occur in the control of the motor 20.

Next, a flowchart will be described.
Step S11: It is determined whether or not there is an instruction to reduce the speed. If there is no instruction to reduce the speed, the process proceeds to step S12, and if there is an instruction to reduce the speed, the process proceeds to step S13.
Step S12: The phase switching time of the medium transport motor 20 is set.
Step S13: The phase switching time of the medium transport motor 20 is set (deceleration setting).
Step S14 The second register 42 of the A / D converter 24 is read.
Step S15: The value of the most significant 2 bits of the register read data 48 is determined. If the value of the most significant 2 bits of the register read data 48 is 00 or 01, the process proceeds to step S16. If the value of the most significant 2 bits of the register read data 48 is 11, the process proceeds to step S19. If the value of the upper 2 bits is 10, the process is terminated.
Step S16 Temperature information of the medium transport motor 20 is set.
Step S17: It is determined whether or not the temperature of the medium transport motor 20 is lower than a specified temperature. If the temperature of the medium transport motor 20 is lower than the specified temperature, the process is terminated. If the temperature of the medium transport motor 20 is not lower than the specified temperature, the process proceeds to step S18.
Step S18: A correction value for motor control corresponding to the current temperature is calculated, and the process ends.
Step S19: The speed down instruction flag is turned on, and the process is terminated.

  As described above, in the present embodiment, the read number counter 52 for detecting that the corresponding register is read at the timing when the time after the occurrence of the interrupt request has continuously passed the time limit is added. Information indicating the detection result of the read number counter 52 is added to a specific portion of the register read data 48.

  Accordingly, information indicating that an interrupt request has been continuously generated can be read by a normal register read cycle in which the register read data 48 is read, and the processing time is extended by reducing the rotation speed of the medium transport motor 20. Can be handled.

  Therefore, even if the phenomenon that the motor control interrupt process cannot be normally completed continues, the control of the medium transport motor 20 that is a stepping motor is not greatly affected.

  In the first and second embodiments, the example in which the image forming apparatus 10 is a thermal transfer printer has been described. However, the present invention is not limited to an inkjet printer, an electrophotographic printer, a facsimile machine, and a copying machine. It can also be applied to MFPs.

  The present invention is not limited to the above-described embodiment, and various modifications can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention.

  The present invention can be used for an interrupt control device and an image forming apparatus.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Control unit 20 Medium conveyance motor 21 Central control part 28 Motor control part 29 Timer 30 Host I / F control part 33 Interrupt request register 34 Interrupt time monitor counter 36 Time monitor count up signal 42 Second register 44 Information addition Circuit 52 Read count counter

Claims (11)

A control unit for executing an interrupt control process of the stepping motor;
An interrupt source that generates an interrupt request; and
An interrupt time monitoring counter that outputs a count-up signal when a time limit has elapsed since the occurrence of an interrupt request of a specific interrupt source among the interrupt sources;
A motor status information register for storing and outputting motor status information indicating the status of the stepping motor;
When the count-up signal is output, an information adding unit that adds additional information to the motor status information output by the motor status information register,
The control unit starts the interrupt control process when an interrupt request of the specific interrupt source is generated, reads the motor state information, and when the additional information is added to the motor state information, An interrupt control device, characterized in that interrupt control processing is terminated halfway. An interrupt request register for notifying the control unit and the interrupt time monitoring counter that the interrupt request has occurred;
The interrupt control apparatus according to claim 1, wherein the interrupt request register notifies the interrupt time monitoring counter only that an interrupt request of a specific interrupt source among the interrupt sources has occurred.   The interrupt control device according to claim 2, wherein the interrupt time monitoring counter starts counting the time limit when receiving a notification from the interrupt request register that an interrupt request for the specific interrupt source has occurred.   The interrupt control device according to claim 1, wherein the information adding unit adds the additional information to a specific bit of the motor state information.   The control unit, when the additional information is added to the motor status information, terminates the interrupt control process in the middle so as not to affect the next interrupt control process occurrence timing. Item 5. The interrupt control device according to any one of Items 1 to 4.   6. The control unit according to claim 1, wherein when the additional information is not added to the motor state information, the control unit ends the interrupt control process after executing a feedback process based on the motor state information. The interrupt control device according to item 1. An elapsed number counter that counts the number of times the time limit has elapsed since the occurrence of the interrupt request of the specific interrupt source in the most recent past and outputs the number of elapsed times;
The information adding unit further adds the number of elapsed times to the additional information,
7. The control unit according to claim 1, wherein when the additional information is added to the motor status information and the number of elapsed times is equal to or greater than a predetermined number, the interrupt control process is terminated halfway. The interrupt control device described in 1.   When the additional information is added to the motor status information and the elapsed number is less than a predetermined number, the control unit extends the processing time of the next interrupt control process, and then performs the interrupt control process. The interrupt control device according to claim 7, which ends.   The elapsed time counter counts the number of times that the time limit has elapsed since the occurrence of an interrupt request of the specific interrupt source in the most recent past interrupt control processing, and outputs the elapsed number of times The interrupt control device according to claim 7 or 8.   The interrupt control device according to any one of claims 7 to 9, wherein the information adding unit adds additional information in which the motor state information is added to a plurality of specific bits of the motor state information.   An image forming apparatus comprising the interrupt control device according to claim 1.

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