JP5321264B2 - Image forming apparatus and image forming program - Google Patents

Description

  The present invention relates to an image forming apparatus and an image forming program, and in particular, in an inkjet image forming apparatus, an encoder signal abnormality caused by dirt and an encoder signal abnormality caused by jamming (JAM, paper jam) are separated, and an encoder signal abnormality caused by dirt is detected. In some cases, the present invention relates to an image forming apparatus and an image forming program capable of continuing printing.

In general, an inkjet image forming apparatus performs recording by scanning a carriage on which a head is mounted. At that time, the encoder scale arranged in the main scanning direction is read by an optical sensor, the carriage position information is acquired, and the ejection timing from the head is generated based on this position information.
However, when the number of times of printing is repeated, there arises a problem that the ejected droplets float in the apparatus and adhere to the encoder scale.
Further, there arises a problem that a part of the paper as the recording medium floats as paper dust and adheres to the encoder scale.

Therefore, a configuration in which the ejection mechanism and the encoder scale are physically separated so that ink mist is not generated, and a mechanism for cleaning the encoder scale or encoder sensor are already known.
In addition, a technique for detecting dirt on an encoder scale using a plurality of sensors is already known.
Further, a technique for detecting dirt by detecting a direction change during a constant speed operation in a recording operation is already known.

However, the conventional structure in which the discharge mechanism and the encoder scale are physically separated and the mechanism for cleaning the encoder scale or encoder sensor have an additional mechanism structure, leading to an increase in cost and machine size. It was.
Further, in the configuration in which the contamination of the encoder scale is detected using a plurality of conventional sensors, there is a problem that the cost increases due to an increase in the number of parts.
Also, in the conventional method of detecting the direction change during constant speed operation in the recording operation, it is impossible to distinguish between an encoder signal error due to a jam and an encoder signal error due to dirt, so in the event of an error it stops immediately to prevent head damage. There was a problem that had to be.

  The present invention has been made in order to solve the above-described conventional problems. The encoder signal abnormality caused by dirt is separated from the encoder signal abnormality caused by jam, and printing can be continued when the encoder signal is abnormal due to dirt. An object is to provide an image forming apparatus and an image forming program.

The following patent documents are considered to be similar to the present invention.
Patent Document 1 discloses an encoder that is assumed to correspond to a DC motor drive instruction for the purpose of notifying the user that the optical scale is soiled and informing the user that the subsequent printing result is not accurate. Is detected and notified based on the difference between the output signal and the actual encoder output signal. Specifically, a configuration is disclosed in which an encoder cycle during constant speed operation is left as a history, and dirt is detected from speed fluctuations after the print end position.
The technique disclosed in Patent Document 1 is similar to the present invention in that it uses an encoder cycle history.

In Patent Document 2, a plurality of encoder sensors are provided on the carriage for the purpose of accurately determining whether or not the linear scale is dirty even during the normal printing sequence, and the maximum of the cycle count values is set. A configuration for determining whether or not the linear scale is soiled based on the value and the minimum value is disclosed.
The technique disclosed in Patent Document 2 is similar to the present invention in that it accurately determines whether or not the linear scale is dirty even during a normal printing sequence.

Further, Patent Document 3 discloses a means for setting the moving direction switching position of the moving member, and a moving member for the purpose of detecting the dirt on the linear scale with a simple configuration and easily grasping the dirt position. A configuration is disclosed that includes means for determining that the linear scale is contaminated when the detecting means detects that the moving direction of the moving member has been switched before reaching the moving direction switching position.
The technique disclosed in Patent Document 3 is similar to the present invention in that an abnormality in an encoder signal can be detected even during a normal printing sequence.

To achieve the above object, the image forming apparatus according to claim 1 prints on a recording medium conveyed by a conveying unit while scanning a carriage mounted with a head for ejecting ink by a carriage driving unit. In
A linear scale (encoder scale 14) arranged in parallel with the scanning direction of the carriage (11 in FIG. 1);
An encoder sensor (13a) mounted on the carriage and reading the linear scale;
Period measuring means (encoder period detecting unit 52 in FIG. 4) for measuring a period in which the carriage reciprocates based on the output of the encoder sensor;
Direction detection means (direction detection unit 54) for detecting a scanning direction based on the output of the encoder sensor;
A cycle history recording unit (encoder cycle history recording unit 55) for recording a history of cycles measured by the cycle measuring unit;
Period abnormality determining means (encoder analyzing unit 50, S104 in FIG. 9) for determining abnormality of the period measured by the period measuring means;
After the period abnormality is detected by the period abnormality determination performed by the period abnormality determination unit, whether the cause of the period abnormality is based on the contamination of the encoder sensor using the period history recorded by the period history recording unit (S105). ) Or a stain / jam cause determination means (encoder analysis unit 50) for determining whether the recording medium is caused by a jam (S107),
When the stain / jam cause determining means determines that the cause of the cycle abnormality is the jam, printing is interrupted (S111), and when the cause of the cycle abnormality is determined to be the stain (S107: no) The printing is continued.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the output of the carriage driving unit is not changed for a certain period after the period abnormality is detected in the period abnormality determination (S112 in FIG. 9). Explanation).

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, a notification unit (operation / display unit 47) for notifying a user of a stain determination result and permission for continuous printing are input. A user input means (operation / display unit 47) for notifying the user of the stain determination result (S204 in FIG. 10) and printing the second and subsequent sheets of the recording medium when continuous printing is permitted It is characterized by doing.
According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect,
The stain determination is not performed on the second and subsequent sheets of the recording medium (S203: no).

According to a fifth aspect of the present invention, there is provided an image forming program in parallel with a carriage on which a head for ejecting ink is mounted, a carriage driving unit that scans the carriage, a conveyance unit that conveys a recording medium, and a scanning direction of the carriage. An image forming apparatus provided with a linear scale arranged in an arrangement and an encoder sensor mounted on the carriage and reading the linear scale;
A cycle measurement process for measuring a cycle in which the carriage reciprocates based on an output of the encoder sensor;
Direction detection processing for detecting a scanning direction based on the output of the encoder sensor;
A period history recording process for recording a history of the period measured in the period measurement process;
Period abnormality determination processing for determining abnormality of the period measured in the period measurement processing;
After detecting a period abnormality in the period abnormality determination in the period abnormality determination process, the cause of the period abnormality using the period history recorded in the period history recording process is based on contamination of the encoder sensor, or Execute the dirt / jam cause determination process to determine whether the recording medium is caused by a jam,
The stain / jam cause determination process is characterized in that printing is interrupted when the cause of the cycle abnormality is determined to be the jam, and printing is continued when the cause of the cycle abnormality is determined to be the stain. And

  According to the first aspect of the present invention, since the dirt determination is performed using the period history after the period abnormality is detected, the processing load can be reduced. Further, by using the cycle history, it is not affected by sudden noise or the like.

According to the second aspect of the present invention, it is possible to realize high accuracy of the dirt determination.
According to the third aspect of the present invention, usability (ease of use by the user) can be improved, and the user can select whether or not to continue printing depending on the degree of contamination.

According to the fourth aspect of the present invention, throughput (processing capacity per unit time) can be improved.
According to the invention described in claim 5, since the stain determination is performed using the cycle history after detecting the cycle abnormality, the processing load can be reduced. Further, by using the cycle history, it is not affected by sudden noise or the like.

1A and 1B are diagrams showing a main part of an embodiment of the present invention, wherein FIG. 1A is a plan view showing a scanning direction of a carriage and a conveying direction of a recording medium (paper), and FIG. FIG. 4C is an enlarged perspective view showing a positional relationship between a main scanning encoder sensor and an encoder scale. (A) is a front view which shows the slit pattern of the said encoder scale, (B) is a figure which shows the output waveform of the A phase and B phase of the said main scanning encoder sensor. 2 is a block diagram illustrating an overall configuration of the image forming apparatus according to the exemplary embodiment. FIG. It is a block diagram of the encoder analysis part which performs the encoder analysis in the said embodiment. 4 is a timing chart of encoder cycle detection, carriage position detection, and timing generation in the encoder analysis unit. It is a timing chart of the direction detection part in the encoder analysis part. 4 is a timing chart of an encoder cycle history recording unit in the encoder analysis unit. It is a figure explaining the difference in the encoder signal in the case of an encoder becoming dirty and a jam. It is a flowchart regarding the jam determination at the time of motor control. It is a flowchart at the time of printing a plurality of sheets, and shows from printing start to printing end.

Hereinafter, the present invention will be described based on the illustrated embodiments.
As shown in FIGS. 1A to 1C, a recording head 11a is mounted on a carriage 11, and the carriage 11 is fitted into a cylindrical guide rod 12 so as to be slidable in the left-right direction (carriage scanning direction). It is. A main scanning encoder sensor 13 a which is an optical sensor having a U-shaped cross section is fixed to the front side surface of the carriage 11. The main scanning encoder sensor 13a is arranged so as to sandwich an encoder scale 14 (see FIG. 2A) described below from the left and right, and optically reads the slit pattern. The encoder scale 14 is arranged in parallel with the scanning direction of the carriage 11.
On the lower surface side of the carriage 11, a sheet (recording medium) 15 that is conveyed in the arrow direction (downward) by a conveying unit (not shown) is disposed. The paper 15 is sequentially printed by the ink ejected from the recording head 11a.

As shown in FIGS. 2A and 2B, the encoder scale 14 is made of a transparent film, and slit patterns are formed at regular intervals d. By optically reading the slit pattern with the encoder sensor 13a, the A-phase and B-phase pulse signals are output with phases shifted by 90 degrees (see FIG. 2B).
Note that a direction detection unit (see FIG. 4) described later detects the operation direction of the carriage 11 from the logical relationship between the A phase and the B phase.

Next, an overall block of the image forming apparatus of the present embodiment will be described with reference to FIG.
As shown in FIG. 3, the image forming apparatus GK includes a PC (personal computer) 20 that sends a print job, a control unit 30 that receives the print job and performs various processes, a carriage 11 that is controlled by the control unit 20, and the like. The motor includes various motors and various sensors that input various signals to the control unit 20.

First, the control unit 30 will be described.
Reference numeral 31 denotes a CPU, which mainly performs arithmetic processing. Reference numeral 31b denotes a host I / F that receives a print job from the PC 20, and is, for example, a USB or a LAN, but is not particularly limited. 32a is a ROM, which stores programs and fonts, 32b is a RAM, is used in a work area used for calculation, an image buffer, etc., and 32c is an NVRAM which is a nonvolatile recording device, and has machine information (version And machine-specific characteristic values) are recorded.
Reference numeral 33 denotes an ASIC, which performs mechanical control, image processing, memory control, I / F with the CPU (31), and the like. Reference numeral 34 denotes an ADC, which converts data acquired from the analog sensor 48 into a digital value. Reference numeral 35 denotes a drive waveform generator, which generates a drive waveform for driving the recording head 11a. Reference numeral 36 denotes a head driver, which controls to eject ink from the recording head 11a.

Reference numeral 37a denotes a main scanning motor driving unit which drives a main scanning motor 41 for scanning the carriage 11. Reference numeral 37b denotes a sub-scanning motor driving unit, which drives the sub-scanning motor 42 and drives the transport belt 43 that transports the paper 15 by driving the sub-scanning motor 42.
Reference numeral 38 denotes an AC bias supply unit which is supplied with a charging roller 44 for charging the transport belt 43 and a high voltage power source used for charging.
A maintenance / recovery mechanism drive unit 39 supplies power to a motor 46 that drives a maintenance / recovery mechanism 45 that performs maintenance of the recording head 11a.

Reference numeral 13a denotes a main scanning encoder sensor, which acquires the moving speed and position information of the carriage 11. Reference numeral 13b denotes a sub-scanning encoder sensor, which acquires sub-scanning rotation speed and position information.
Reference numeral 47 denotes an operation / display unit, which includes a switch and a touch panel for notifying the user of the machine state, notifying the usage method, and performing an operation.

Next, encoder analysis in the present embodiment will be described with reference to FIG.
Noise is removed from the encoder signal input from the main scanning encoder sensor 13 a by the noise filter unit 61.
The encoder analysis unit 50 includes the following units.
That is, they are the encoder timing signal generation unit 51, encoder cycle detection unit 52, carriage position detection unit 53, direction detection unit 54, and encoder cycle history recording unit 55.
Then, period detection, carriage position detection, direction detection, and period history recording are performed using the encoder signal after the noise filter.

The encoder analysis unit 50 has a function of generating an encoder timing signal used by the head ejection control unit 62. The head ejection control unit 62 performs head ejection control based on the encoder timing signal.
The motor control unit 63 performs servo control based on the carriage position information, the carriage movement direction, and the encoder cycle detected by the encoder analysis unit 50. As a result, the carriage 11 is scanned and recording on the paper 15 is performed.

Next, the encoder analysis unit 50 will be described with reference to FIG.
An encoder timing signal is generated based on the edge of the encoder signal A phase from which noise has been removed by the noise filter 61.
The encoder timing signal is output for one pulse in synchronization with the system clock or a reference clock obtained by dividing the system clock.
The cycle counter of the encoder cycle detection unit 52 measures the cycle of the encoder timing signal. The position counter for detecting the carriage position increments every time the timing signal is asserted or decrements when the direction is reversed.

  In this example, the timing signal is described as being output at the rising edge of the A phase. However, when the scanning direction of the carriage 11 is reversed, the timing signal is output at the falling edge. However, the present invention is not limited to this, and the timing signal may be generated by edge changes in both the A phase and the B phase. Further, different signals may be used for increment / decrement of the position counter. In that case, a separate timing signal for ejection is required.

As shown in FIG. 6, the direction detection unit 54 detects the scanning movement direction (main scanning movement direction) of the carriage 11. The main scanning encoder sensor 13a mounted on the carriage 11 outputs an encoder signal composed of A phase and B phase.
The direction detection unit 54 detects the scanning direction of the carriage 11 from the phase relationship between the A phase and the B phase. The direction detection timing is determined in synchronization with the system clock in the ASIC (33), and the direction is determined every time the A phase or the B phase is switched.
For example, in the above example, when the direction detection signal is “H”, the forward path is indicated, and when the direction detection signal is “L”, the backward path is indicated.
In the motor control for driving the carriage 11, the scanning direction of the carriage 11 is recognized from the direction detected by the direction detection.

As shown in FIG. 7, the encoder cycle history recording unit 55 records the value of the cycle counter in the register cycle history 1 of the ASIC (33) at the timing when the above-described cycle counter starts measurement. Although an example of a register is shown here, a memory such as an SRAM may be used.
Similarly, the value of the period history 1 is recorded in the period history 2 at the timing when the period history 1 records the value of the period counter.
At the same timing, the value of the period history 2 is recorded in the period history 3 and the value of the period history 3 is recorded in the period history 4.
As described above, each period history has a shift register configuration, and the latest period is recorded in the period history 1.

The periodic history recording function can be stopped by software. This is to prevent the history from being updated while referring to each cycle history, and the measurement operation of the cycle counter is continued even when the cycle is stopped.
In addition, each period history has a read flag, and the flag is set to 1 when the reference is made by software. Each flag is configured to shift at the same time when the cycle history is updated, and has a one-to-one relationship with the measured cycle.

In the figure, the upper waveform shows an example when the encoder sheet (encoder scale 14) is dirty. The lower waveform shows an example when a jam occurs.
When dirt such as ink mist or paper dust adheres to the encoder sheet, a phenomenon that part of the encoder signal is lost or buried occurs. However, if there is no change in the motor output during constant speed movement in the printing area, a normal encoder cycle can be obtained after passing through the dirty part.

Further, when a jam occurs, a load opposite to the traveling direction of the carriage 11 is applied when the recording medium (paper 15) contacts the carriage 11. The same applies not only to the paper 15 but also when other foreign matters are present on the carriage scan.
Therefore, when the motor output does not change, the speed of the carriage 11 decreases. That is, the ON / OFF width of the encoder signal is expanded as compared with the assumed speed.
In particular, when a load is applied to the carriage 11 due to a jam or a foreign object, the recording head 11a may be damaged.

FIG. 9 is a flowchart regarding jam determination during motor control, and shows a flow of operations from the start of movement of the carriage to the end of movement.
When the movement of the carriage 11 is started, the servo control calculation is not performed until the servo control cycle time elapses after the previous calculation (S101: no), and when the servo control cycle time elapses ( (S101: yes), the cycle used for servo control is acquired (S102).
At this time, if it is not moving at a constant speed (S103: no), the PID control calculation is performed as it is (S109), and the motor output is updated (S110).

  When moving at a constant speed (S103: yes), it is determined whether the acquired cycle is within the normal range. If the cycle is normal (S104: no), it is determined whether the cycle error flag remains. . If the period abnormality flag remains (S105: yes), the flag clear condition is determined (S107). If the period abnormality flag does not remain (S105: no), the PID control calculation is performed as it is (S109). If the cycle is abnormal in S104 (S104: yes), the jam is determined (S107), if it is not a jam (S107: no), the cycle error flag is set (S108), and the motor output is not updated. An end determination (S112) is performed. Here, the motor output is not updated, as explained in FIG. 8, when a cycle abnormality due to dirt or the like occurs during constant speed movement, if the motor output does not change, the cycle returns to a normal cycle after a certain period. I hope that.

In S104, abnormality determination is performed based on whether the encoder signal period acquired from the encoder signal exceeds an upper limit value or a lower limit value stored in advance. The upper limit value or the lower limit value used here may be set in consideration of a target speed, speed variation, temperature, and the like.
If the flag clear condition is satisfied in S106 (S106: yes), the cycle abnormality flag is cleared (S113), and the PID control calculation is performed as in the normal state (S109). If the flag clear condition is not satisfied (S106: no), the process proceeds to S112.
In the jam determination of S107, if the cycle abnormality continues for the number of times determined by the servo control cycle, it is determined as a jam and jam processing is performed (S111).

Specifically, the time when the carriage 11 starts to move is set to 0, and every time it is determined that the cycle is abnormal in S104 (S104: yes), the number of occurrences of the cycle abnormality is counted up. That is, when the cycle width as described in the example of jam (paper jam) in FIG. 8 continues and expands, it is determined that the cycle is abnormal every servo control cycle, and is counted up. A jam is determined when the number of occurrences of periodic abnormalities reaches the preset number of times.
If the flag clear condition is satisfied in S106 (S106: yes), it can be determined that the period abnormality that occurred before is due to dirt adhering to the encoder scale 14, so the number of period abnormality occurrences is cleared. .

Table 1 is a table showing periodic abnormality flag clear condition determination.
In the flag clear condition determination in S106 of FIG. 9, the determination is performed using the period history. A cycle history is acquired in order from the newest one, and it is determined whether it falls within a predetermined upper limit value and lower limit range (cycle determination column in Table 1). If an abnormal value (× in Table 1) is found before reaching the predetermined history number N, the flag clear determination is NG and the process proceeds to the next flow.
If the predetermined history number N is reached, the flag clear determination is OK, and it is determined that the encoder cycle has returned to normal.
In this example, the flag clear determination is performed by software, but a flag clear determination circuit may be mounted by hardware. For example, a register that sets the upper and lower limits of the cycle and a register that sets the number of histories N are provided, a comparator (output 1 if within the range) between the output value of each cycle register and the upper and lower limit values, and A configuration in which the output value is ANDed by the history number N is conceivable.

  The meaning of the period abnormality flag clearing operation means that a normal encoder period is obtained for a certain period after the period abnormality occurs. That is, it means that an abnormal period occurred temporarily due to ink mist, paper powder, etc. adhering, and a normal period was obtained after passing the adhering part. Since this is not caused by a jam, no load is generated on the carriage 11. Therefore, it is not necessary to stop immediately, and it is possible to continue the printing operation.

As shown in FIG. 10, when printing starts, the first sheet is printed (S201). If the number of printed sheets has not been completed (S202: no), it is determined whether there is any dirt during the printing operation for the first sheet (S203). Here, the stain determination means that a cycle abnormality is detected once in FIG. 9 and the flag is cleared by flag clear determination.
If there is a stain, the print result may differ from the result desired by the user, so that the operation / display unit 47 (see FIG. 3) is notified that an abnormality has occurred (S204). Alternatively, display may be performed by a host-side printer driver such as the PC (20) via the host I / F (31b). In addition, at the same time as notification that an abnormality has occurred, a display is performed so that the user can select whether or not the second and subsequent sheets can be output continuously from the printing result of the first sheet. If the instruction from the user is OK (S205: yes), the printing is continued.
The stain determination in S203 may be ignored for the second and subsequent sheets. In that case, the operation flow of S203: no is forced.

  The image forming method (printing control method shown in FIGS. 9 and 10) in the image forming apparatus described in the above embodiment can be executed by a program stored in a main body memory such as a ROM. A program for executing this image forming method can be provided, for example, by downloading from the Internet, and can be installed from the information processing apparatus (host apparatus) to the image forming apparatus. The present invention is also applied to an aspect of a recording medium on which a program for executing the image forming method is recorded so as to be executable by the image forming apparatus. Further, it may be configured to be executed by a printer driver of the information processing apparatus. That is, the above-described image forming method may be executed by an image forming system in which the information processing apparatus and the image forming apparatus according to the present invention are connected by a communication line or the like.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

GK: Image forming apparatus 11: Carriage 11a: Recording head 13a: Main scanning encoder 14: Encoder scale 20: PC
30 ... Control unit

JP 2008-238685 A JP 2005-279935 A JP 2008-229922 A

Claims (5)

In an image forming apparatus that prints on a recording medium conveyed by a conveying unit while scanning a carriage mounted with a head for discharging ink by a carriage driving unit.
A linear scale arranged in parallel with the scanning direction of the carriage;
An encoder sensor mounted on the carriage and reading the linear scale;
A period measuring means for measuring a period in which the carriage reciprocates based on an output of the encoder sensor;
Direction detecting means for detecting a scanning direction based on an output of the encoder sensor;
A period history recording means for recording a history of periods measured by the period measuring means;
Period abnormality determining means for determining abnormality of the period measured by the period measuring means;
After detecting a period abnormality in the period abnormality determination performed by the period abnormality determination unit, the cause of the period abnormality using the period history recorded by the period history recording unit is based on contamination of the encoder sensor, or A stain / jam cause determining means for determining whether the recording medium is caused by a jam,
The stain / jam cause determination means interrupts printing when the cause of the cycle abnormality is determined to be the jam, and continues printing when the cause of the cycle abnormality is determined to be the stain. An image forming apparatus. The image forming apparatus according to claim 1.
An image forming apparatus, wherein the output of the carriage driving unit is not changed for a certain period after detecting the periodic abnormality in the periodic abnormality determination. The image forming apparatus according to claim 1, wherein:
A notification means for notifying the user of the stain determination result, and a user input means for inputting permission for continuous printing,
An image forming apparatus that prints the second and subsequent sheets of the recording medium when notifying a user of the stain determination result and receiving permission to continue printing. The image forming apparatus according to claim 3.
The image forming apparatus, wherein the stain determination is not performed on the second and subsequent sheets of the recording medium. Carriage mounted with a head for ejecting ink, carriage drive means for scanning the carriage, transport means for transporting a recording medium, a linear scale arranged in parallel with the scanning direction of the carriage, and mounted on the carriage And an image forming apparatus comprising an encoder sensor for reading the linear scale,
A cycle measurement process for measuring a cycle in which the carriage reciprocates based on an output of the encoder sensor;
Direction detection processing for detecting a scanning direction based on the output of the encoder sensor;
A period history recording process for recording a history of the period measured in the period measurement process;
Period abnormality determination processing for determining abnormality of the period measured in the period measurement processing;
After detecting a period abnormality in the period abnormality determination in the period abnormality determination process, the cause of the period abnormality using the period history recorded in the period history recording process is based on contamination of the encoder sensor, or Execute the dirt / jam cause determination process to determine whether the recording medium is caused by a jam,
The stain / jam cause determination process is characterized in that printing is interrupted when the cause of the cycle abnormality is determined to be the jam, and printing is continued when the cause of the cycle abnormality is determined to be the stain. An image forming program.