JP6834332B2 - Image forming device and image forming method - Google Patents

Description

The present invention relates to an image forming apparatus and an image forming method.

Conventionally, as an example of an image forming apparatus equipped with a liquid discharge unit, a T-shirt printer (cloth printer) that easily prints an image on a personal computer (PC), etc., transports a recording medium flat mainly for industrial use. To print. At this time, a method of detecting the height of the recording medium so that the liquid discharge head does not collide with the recording medium and automatically adjusting the gap between the liquid discharge head and the recording medium is applied. Here, the liquid discharge unit is a functional component that discharges and ejects liquid from a nozzle.

However, if the recording medium has irregularities and the position where the gap is automatically adjusted is the concave portion of the recording medium, the gap between the convex portion of the recording medium and the liquid discharge head becomes small, and the liquid discharge head and the recording medium are separated from each other. It causes the problem of collision and jamming.

Therefore, a technique has been proposed in which the liquid discharge unit is likely to collide with the liquid discharge head and the recording medium. For example, "an image forming apparatus and an image forming method" (Patent Document) that suppresses a decrease in throughput when printing a large number of recording media at high speed and prevents contact between an inkjet head (liquid ejection head) and a recording medium. 1).

In the technique according to Patent Document 1 described above, the paper height indicating the amount of floating of the recording medium from the transport portion is detected, and the recording medium is conveyed, ink droplets are ejected, and the liquid ejection head is ejected according to the paper height. Controls at least one or more of the relative distances from the carrier. This has a function of preventing printing when there is a possibility that the liquid discharge head and the recording medium collide with each other. However, with such a function, if there is a possibility that the liquid ejection head and the recording medium collide with each other, printing can be executed with the printing stopped unless some improvement is made to the recording medium. There is a problem that it is inconvenient because it cannot be done.

The present invention has been made to solve such a problem, and a technical problem thereof is that a collision between a liquid discharge head and a recording medium can be avoided, and printing can be executed even in a situation where printing is not possible. An object of the present invention is to provide an image forming apparatus and an image forming method.

In order to solve the above technical problems, one embodiment of the present invention includes a transport means for transporting a recording medium, a carriage for printing on the recording medium conveyed by the transport means with a liquid discharge head, and the recording. Before printing, it is determined whether or not the liquid discharge head and the recording medium collide with each other in the gap adjusting means for adjusting the gap between the medium and the liquid discharge head and the gap adjusted by the gap adjusting means to cause a jam. In an image forming apparatus including a jam detecting means for detecting from the entire recording medium and a control means for controlling to stop printing when a jam is detected by the jam detecting means, the control means is the jam. when jam is detected by the detection means, when in the instruction to the gap adjusting means such that the gap does not occur the jamming at the next printing to set for changing the gap, the recording by the gap adjusting means It is characterized by randomly shifting the position of the medium.

According to the present invention, according to the above configuration, a collision between the liquid discharge head and the recording medium can be avoided, and printing can be executed even in a situation where printing is not possible. Issues, configurations and effects other than those described above will be clarified by the following description of the embodiments.

In order to explain the technical outline of the image forming apparatus of this invention, it is a figure which illustrated the positional relationship between the recording medium which jam is detected after gap adjustment, and the carriage provided with the liquid discharge head. FIG. 1A shows a schematic view showing an example of the case where jam does not occur from the front direction of the above positional relationship, and FIG. 1B shows another example of the case where jam occurs from the side direction of the above positional relationship. It is a schematic diagram. FIG. 1C is a schematic view showing another example of the case where the occurrence of jam can be avoided from the side direction of the above positional relationship. In order to explain another technical outline of the image forming apparatus of this invention, it is a figure which illustrated the positional relationship between the recording medium and the carriage provided with the liquid discharge head according to the number of times of printing overlap. It is a block diagram which showed the basic structure of the liquid discharge unit which is the main part of the image forming apparatus which concerns on Example 1 of this invention. FIG. 3 is a block diagram showing a detailed configuration of a control unit of the liquid discharge unit shown in FIG. 3, including peripheral devices. It is a schematic diagram for demonstrating the outline of the flow (sequence) of the processing procedure from the height adjustment of a platen by the control unit shown in FIG. 4 to printing on a recording medium. FIG. 5A is a schematic diagram of the procedure of the initial processing after the power is turned on, and FIG. 5B is a schematic diagram of the procedure of the printing instruction processing and the printing execution processing. FIG. 5 is a flowchart showing an operation process of adjusting the gap between the liquid discharge head and the recording medium by the control unit shown in FIG. FIG. 6A is a flowchart showing the operation process when the Nth print instruction is given, and FIG. 6B is the N + 1th print instruction when the Nth print instruction is not executed. It is a flowchart which shows operation process. It is a flowchart which shows the operation process of the gap adjustment between a liquid discharge head and a recording medium by the control part of the liquid discharge unit which is the main part of the image forming apparatus which concerns on Example 2. FIG. FIG. 7 (a) is a flowchart showing the operation process when the Nth print instruction is given, and FIG. 7 (b) is the case where the N + 1th print instruction is given when the Nth print instruction is not executed. It is a flowchart which shows operation process. FIG. 7C is a flowchart showing an operation process when the N + 2nd print instruction is given when the Nth and N + 1th print instructions are not executed. It is a flowchart which shows the operation process of the gap adjustment between a liquid discharge head and a recording medium by the control part of the liquid discharge unit which is the main part of the image forming apparatus which concerns on Example 3. FIG. FIG. 8A is a flowchart showing the operation process when the Nth print instruction is given, and FIG. 8B is the N + 1th print instruction when the Nth print instruction is not executed. It is a flowchart which shows operation process. It is a flowchart which shows the operation process at the time of giving the Nth printing instruction about the gap adjustment between a liquid discharge head and a recording medium by the control part of the liquid discharge unit which is the main part of the image forming apparatus which concerns on Example 4. FIG. FIG. 5 is a flowchart showing an operation process of adjusting a gap between a liquid discharge head and a recording medium by a control unit of a liquid discharge unit, which is a main part of the image forming apparatus according to the fifth embodiment. FIG. 10A is a flowchart showing an operation process when the Nth printing instruction including printing overlap is performed, and FIG. 10B is a flowchart showing an operation process related to the Nth printing overlap. 6 is a flowchart showing an operation process of adjusting a gap between a liquid discharge head and a recording medium by a control unit of a liquid discharge unit, which is a main part of the image forming apparatus according to the sixth embodiment. FIG. 11A is a flowchart showing an operation process when the Nth printing instruction including printing overlap is performed, and FIG. 11B is a flowchart showing an operation process related to the Nth printing overlap. FIG. 5 is a flowchart showing an operation process of adjusting a gap between a liquid discharge head and a recording medium by a control unit of a liquid discharge unit, which is a main part of the image forming apparatus according to the seventh embodiment. FIG. 12A is a flowchart showing the operation process when the Nth printing instruction including the Nth printing overlap is performed, and FIG. 12B is a flowchart showing the operation process related to the Nth printing overlap. FIG. 5 is a flowchart showing an operation process of adjusting a gap between a liquid discharge head and a recording medium by a control unit of a liquid discharge unit, which is a main part of the image forming apparatus according to the eighth embodiment. FIG. 13 (a) is a flowchart showing an operation process when the Nth printing instruction including printing overlap is performed, and FIG. 13 (b) is a flowchart showing an operation process related to the Nth printing overlap.

Hereinafter, the image forming apparatus and the image forming method of the present invention will be described in detail with reference to the drawings.

First, the technical outline of the image forming apparatus of the present invention will be briefly described. This image forming apparatus adjusts the gap between the transport means for transporting the recording medium, the carriage for printing on the recording medium conveyed by the transport means with the liquid discharge head, and the gap between the recording medium and the liquid discharge head. Means and. In addition, a jam detecting means that detects from the entire recording medium whether or not the liquid discharge head and the recording medium collide with each other in the gap adjusted by the gap adjusting means to cause jam, and a jam detecting means that detects jam. A control means for controlling to stop printing when the printing is performed is provided. In such a basic configuration, when a jam is detected by the jam detecting means at the time of the current printing by the control means, the gap adjusting means is instructed to change the gap so that the jam is not generated at the next printing.

In short, in this image forming apparatus, the gap between the liquid ejection head and the recording medium is adjusted by the gap adjusting means at the time of the current printing. After that, the height of the recording medium is detected by the jam detecting means, and when it is considered that a jam is generated even in a part of the recording medium, there is a control for instructing and controlling these operations. Stop printing by means. Further, at this time, the control means instructs the gap adjusting means to change the gap so that jam does not occur at the time of the next printing, and the position of the recording medium is changed.

FIG. 1 is a diagram illustrating the positional relationship between the recording medium 1 in which jam is detected after gap adjustment and the carriage 100 provided with the liquid discharge head in order to explain the technical outline of the image forming apparatus of the present invention. FIG. 3A shows a schematic view showing an example of the case where jam does not occur from the front direction of the above positional relationship, and FIG. 3B shows another example of the case of generating jam from the side direction of the above positional relationship. It is a schematic diagram. FIG. 3C is a schematic view showing another example of the case where the occurrence of jam can be avoided from the side direction of the above positional relationship.

More specifically with reference to FIG. 1A, in the gap adjustment by the gap adjusting means at the time of current printing, the platen 2 which is a pressure plate for pressing the recording medium 1 against the plate surface is moved up and down to move the recording medium 1. The gap (height) Δh between the carriage 100 and the liquid discharge head of the carriage 100 is adjusted. After adjusting the gap Δh at a certain position of the recording medium 1, the platen 2 is moved in the horizontal direction (for example, to the right), and jam occurs depending on whether or not the recording medium 1 collides with the liquid discharge head of the carriage 100. Determine the presence or absence.

The platen 2 can be moved independently as a jam determination operation, or can be performed in addition to other operations such as when the recording medium 1 is moved to the print start position. Regarding the determination of the presence or absence of jam in the recording medium 1, the optical detection means for receiving the irradiation light from the light emitting elements 3 such as LEDs arranged above both ends of the recording medium 1 serving as the jam detection means by the light receiving element 4. Is responsible. Specifically, the height of the light ray blocking point up to the top of the recording medium 1 in the height direction, or, in a simple concept, the height of the entire recording medium 1 is detected. As a result, it is performed by detecting the degree to which the received light received by the light receiving element 4 is blocked by the convex portion of the recording medium 1, and when the received light received falls below a predetermined threshold value, a jam occurs. Can be regarded.

For example, if the recording medium 1 has no irregularities and is flat as shown in FIG. 1A, printing can be performed without detecting the occurrence of jam in the state of the gap Δh regardless of the position where the gap is adjusted in the recording medium 1. .. However, as shown in FIG. 1B, when the recording medium 1'is uneven and the height-adjusted position is a concave portion, a gap Δh ″ (<Δh) is formed and the liquid of the carriage 100 is discharged. The occurrence of jam in which the head 118 and the convex portion of the recording medium 1 collide is detected. In such a case, the control means stops printing. However, even in the situation where jam occurs, it is tentatively shown in FIG. 1 (c). If the gap Δh ′ (> Δh ″) is changed so as to be large and the setting is made so that jam does not occur at the time of the next printing, the printing can be performed without any trouble.

That is, in the image forming apparatus of the present invention, when printing is not performed because the liquid discharge head 118 and the recording medium 1'collide with each other, the gap Δh'between the liquid discharge head 118 and the recording medium 1'is formed at the next printing. Change and make it bigger. As a result, the collision between the liquid discharge head 118 and the recording medium 1'can be avoided, and printing can be executed even in a situation where printing is not possible.

By the way, the processing function of each part of the image forming apparatus described above can be paraphrased as the processing process of the image forming method. That is, the image forming method of the present invention includes a transfer step in which the transfer means conveys the recording medium, and a printing step in which printing is performed using the liquid discharge head built in the recording medium in which the carriage is conveyed in the transfer step. Has. In addition, the gap adjusting means adjusts the gap between the recording medium and the liquid discharge head, and the jam detecting means collides with the liquid discharge head and the recording medium in the gap adjusted in the gap adjusting step to jam. It has a jam detection step of detecting whether or not it occurs from the entire recording medium before printing. Further, the control means has a control step for controlling to stop printing when a jam is detected in the jam detection step. Based on this processing process, in the control step, when a jam is detected in the jam detection step during the current printing, the control means instructs the gap adjusting means in the gap adjusting step to change the gap and jam at the next printing. It is a setting to prevent it from occurring. Each of these steps can be used to build a program to be executed by a computer. In addition, the program can be stored in a recording medium, read by a computer, and executed.

Next, another technical outline of the image forming apparatus of the present invention will be briefly described. In the image forming apparatus of the present invention, when the above-mentioned control means instructs the recording medium to perform printing overlaps for printing twice or more, the image forming apparatus instructs the gap adjusting means as the number of times of printing overlaps during the printing overlaps. It has a function to change the gap between the recording medium and the liquid discharge head so as to widen.

In short, in the image forming apparatus, the control means instructs the gap adjusting means to change the gap between the recording medium and the liquid ejection head as the number of times of printing is repeated. As a result, in cooperation with the function of the jam detecting means of the image forming apparatus, the collision between the liquid discharge head 118 of the carriage 100 and the recording medium can be more accurately avoided, and printing can be executed even in a situation where printing is not possible. it can.

FIG. 2 is a diagram illustrating the positional relationship between the recording medium 11 and the carriage 100 provided with the liquid discharge head 118 according to the number of printing overlaps in order to explain another technical outline of the image forming apparatus of the present invention. ..

Referring to FIG. 2, in the initial state in which the liquid ejection head 118 of the carriage 100 shown in the uppermost stage of FIG. 2 does not eject liquid such as ink to the recording medium 11, the control means moves to the gap adjusting means. Instruct and lower the platen 2 to a predetermined position. As a result, the gap between the recording medium 11 and the liquid discharge head 118 is maintained at a predetermined interval. Further, in the state where the liquid ejection shown in the middle part of FIG. 2 is started, a bulge is formed in the printing portion 5 of the recording medium 11 due to the printing overlap of ink and the like. Therefore, even in this state, the control means instructs the gap adjusting means to lower the platen 2 again so that the subsequent printing overlay can be executed. Further, in the state where the liquid ejection shown at the bottom of FIG. 2 is continued, a larger swelling is formed in the printing portion 5'of the recording medium 11 due to the continuous printing of ink or the like. Therefore, even in this state, the control means instructs the gap adjusting means to lower the platen 2 again so that the subsequent printing overlay can be executed. After that, the platen 2 is lowered every time the print overlay is continued in the same procedure so that the print overlay can be continued. Of course, since the number of overprints, the number of times the platen 2 is lowered, and the amount of movement are limited, the number of times of overprinting and the number of times the platen 2 is lowered may be set in advance to an allowable range value.

By the way, the processing function of the other technical outline of the image forming apparatus described above can be paraphrased as the processing process of the image forming method. That is, the image forming method of the present invention in this case is based on the fact that the control means has a processing process for instructing the printing overlap for printing on the recording medium twice or more in the control step. In the control step, the control means instructs the gap adjusting means in the gap adjusting step to widen the gap between the recording medium and the liquid ejection head as the number of times of printing overlaps during the printing stacking. is there. This step can also be used to build a program to be executed by a computer. In addition, the program can be stored in a recording medium, read by a computer, and executed. The image forming apparatus of the present invention will be specifically described below with reference to some examples.

FIG. 3 is a block diagram showing a basic configuration of a liquid discharge unit which is a main part of the image forming apparatus according to the first embodiment of the present invention.

Referring to FIG. 3, this liquid discharge unit holds the carriage 100 by a slide rail 104 integrated with the sheet metal, and a timing belt 102 bridged between the drive pulley 106 and the driven pulley 107 by the main scanning motor 105. The moving scan is performed in the main scanning direction via. In the carriage 100, a liquid ejection head 118 composed of four liquid ejection heads for ejecting ink droplets of four colors is orthogonal to a nozzle row on a nozzle surface having a plurality of ink ejection ports (nozzles) formed in the main scanning direction. They are arranged in the direction (sub-scanning direction), and are mounted with the ink ejection port direction facing downward. Examples of the four colors being yellow (Y), cyan (C), magenta (m), and black (K) can be exemplified. Although the case where an independent droplet ejection head is used is illustrated here, one or a plurality of head configurations having a plurality of nozzle rows for ejecting droplets of recording liquid of each color can also be adopted. .. Moreover, the number of colors and the arrangement order are not limited to this.

As the inkjet head constituting the liquid discharge head 118, a configuration having a pressure generating means for generating a pressure for discharging droplets or the like can be used. Examples of the pressure generating means include a piezoelectric actuator such as a piezoelectric element and a thermal actuator that utilizes a phase change due to boiling of a liquid film by using an electric heat conversion element such as a heat generating resistor. In addition, shape memory alloy actuators that use metal phase changes due to temperature changes, electrostatic actuators that use electrostatic force, and the like can be mentioned. Further, an encoder scale 103 having a slit formed in the carriage 100 is provided along the main scanning direction, and the carriage 100 is provided with an encoder sensor 117 for detecting the slit of the encoder scale 103. These constitute a linear encoder for detecting the position of the carriage 100 in the main scanning direction.

On the other hand, in order to transport the recording medium 108, a transport belt 101 is provided, which is a transport means for electrostatically adsorbing the recording medium 108 and transporting the recording medium 108 at a position facing the liquid discharge head 118. The transport belt 101 is driven by rotationally driving the transport roller 109 via a timing belt 114 bridged between the transport drive pulley 112 and the transport roller pulley 113 by a sub-scanning motor 111. Further, the transfer belt 101 is provided with an encoder wheel 115 having a slit formed coaxially with the transfer roller 109, and a side plate (not shown) is provided with an encoder sensor 116 for detecting the slit of the encoder wheel 115. These constitute a wheel encoder for detecting the position of the transport belt 101 in the sub-scanning direction.

The transport belt 101 is an endless belt, which is bridged between the transport roller 109 and the tension roller 110 and is configured to orbit in the belt transport direction (sub-scanning direction), and is charged while moving around. It is charged (charged) by the rollers. Further, the transport belt 101 may be a belt having a one-layer structure or a belt having a multi-layer structure (two or more layers). When the transport belt 101 has a one-layer structure, it comes into contact with the recording medium 108 and the charging roller, so that the entire layer needs to be formed of an insulating material. Further, in the case of a multi-layer structure, it is preferable that the side that contacts the recording medium 108 and the charging roller is formed of an insulating layer, and the side that does not contact the recording medium 108 and the charging roller is formed of a conductive layer. The liquid discharge unit described with reference to FIG. 3 is not limited to the applicable range of a general-purpose image forming apparatus. That is, it can be applied to other forms such as an image forming apparatus of other digital multifunction device (MFP: Multifunction Peripheral) specifications and an apparatus for printing on cloth or the like as a recording medium 108.

FIG. 4 is a block diagram showing a detailed configuration of the control unit of the liquid discharge unit described above, including peripheral devices.

Referring to FIG. 4, the control unit 200 in this liquid discharge unit includes a CPU 202, a ROM 203, a RAM 204, an NVRAM 205, and an ASIC 206. The CPU 202 is connected to an operation panel 213 for inputting and displaying information necessary for the device, and controls the entire device. In addition, it also has a function of controlling the transfer operation of the recording medium 108 and the movement operation of the liquid discharge head 118 of the carriage 100. The ROM 203 stores a program executed by the CPU 202 and other fixed data. RAM204, image data, etc. are temporarily stored. The NVRAM 205 is a rewritable non-volatile memory for holding data even while the device power is cut off. The ASIC 206 processes various signal processing for image data, image processing for sorting, and other input / output signals for controlling the entire device.

Further, the control unit 200 includes a host interface (I / F) 201, a print control unit 208, a main scanning motor drive unit 209, a gap adjustment unit 210, a sub-scanning motor drive unit 211, and an input / output (I / 0) unit 207. It has. The host interface (I / F) 201 plays a role of transmitting / receiving data and signals to / from the host side such as the printer driver 212. The print control unit 208 generates a drive waveform for driving the liquid discharge head 118, and outputs image data for selectively driving the pressure generating means of the liquid discharge head 118 and various data associated therewith to the head driver 119. .. The main scanning motor drive unit 209 drives the main scanning motor 105. The gap adjusting unit 210 instructs the platen elevating motor 121 that elevates and elevates the platen 2 to adjust the gap. The sub-scanning motor drive unit 211 plays a role of driving the sub-scanning motor 111 that drives the conveyor belt 101. The input / output (I / 0) unit 207 inputs detection pulses from the linear encoder 120, the encoder wheel 115, and detection signals from various other sensors.

The control unit 200 receives print data and the like at the host interface (I / F) 201 via a cable or network, and temporarily stores the print data in the reception buffer. The print data is generated by, for example, a printer driver 212 of a host function of an information processing device such as a personal computer (PC), an image reading device such as an image scanner, or an imaging device such as a digital camera. In the control unit 200, the CPU 202 reads out and analyzes the print data in the reception buffer included in the host interface (I / F) 201. Further, according to the analysis result, the ASIC 206 performs necessary image processing, data sorting processing, and the like, and transfers the data to the print control unit 208. Therefore, the print control unit 208 outputs the image data and the drive waveform to the head driver 119 at a required timing. The dot pattern data for outputting the image may be generated by storing the font data in the ROM 203, for example, or the printer driver 212 on the host side expands the image data into bitmap data and transfers the image data to the apparatus. You may do so. Here, for example, it is assumed that the printer driver 212 is used.

The drive waveform generation unit of the print control unit 208 includes a D / A converter, an amplifier, and the like that perform D / A conversion of the drive pulse pattern data stored in the ROM 203 and read by the CPU 202. Then, a drive waveform composed of one drive pulse or a plurality of drive pulses is output to the head driver 119. The head driver 119 drives the liquid discharge head 118 based on image data (dot pattern data) corresponding to one line of the liquid discharge head 118 serially input. For this purpose, the head driver 119 selectively applies the drive pulses constituting the drive waveform given by the drive waveform generation unit of the print control unit 208 to the pressure generating means of the liquid discharge head 118.

The head driver 119 includes, for example, a shift register for inputting a clock signal and serial data which is image data, and a latch circuit for latching a register value of the shift register with a latch signal. In addition, a level conversion circuit (level shifter) that changes the output value of the latch circuit, an analog switch array (switch means) whose on / off is controlled by this level shifter, and the like are included. Functionally, a case can be exemplified in which a required drive pulse included in the drive waveform is selectively applied to the pressure generating means of the liquid discharge head 118 by controlling the on / off of the analog switch array. The gap adjusting unit 210 drives the platen 2 up and down by the platen elevating motor 121. Then, the gap adjusting unit 210 adjusts the gap (height) of the recording medium 108 according to the result of determining the presence or absence of the occurrence of jam by the optical detection means by the light emitting element 3 and the light receiving element 4 described above.

FIG. 5 is a schematic diagram for explaining an outline of the flow (sequence) of the processing procedure from the height adjustment of the platen 2 to the printing on the recording medium 108 by the control unit 200 described above. FIG. 3A is a schematic diagram of the procedure of initial processing after the power is turned on, and FIG. 3B is a schematic diagram of the procedure of print instruction processing and print execution processing.

Referring to FIG. 5A, in the initial processing after the power is turned on, when the power button is first pressed, the gap adjusting unit 210 instructs the platen elevating motor 121 (see FIG. 4) to drive the platen 2 upward. To do. Therefore, after detecting this state by the optical detection means (only the light emitting element 3 is shown), the platen 2 is lowered by a predetermined amount and then moved to the front side. The recording medium 108 is set in a state of being moved to the front side. The recording medium 108 here may be regarded as a T-shirt or the like in practical use.

With reference to FIG. 5B, the upper row relates to the print instruction process, and when a print instruction is given on the operation panel 213 and a job is input (first step), the platen 2 is optically detected by the optical detection means (light emitting element 3). Move directly below (second step). After that, the gap adjusting unit 210 instructs the platen elevating motor 121 to move the platen 2 upward, and stops (third step) when it touches the optical detection means (light blocking of the light emitting element 3). Further, the gap adjusting unit 210 instructs the platen elevating motor 121 to move the platen 2 down a certain distance (fourth procedure). After that, after moving to the front side (fifth step), the presence or absence of jam is detected by performing a full-width scan with the optical detection means (light emitting element 3) while moving to the print standby position on the rear side once. (Sixth step). If the occurrence of jam is not detected, printing is performed after that, but if the occurrence of jam is detected, printing is not performed.

The lower part of FIG. 5B relates to the printing execution process. If the occurrence of jam is not detected, printing is performed from the print standby position (7th step), and the printing is completed by moving in the sub-scanning direction (8th step). (Procedure), the platen 2 is lowered by a predetermined amount (9th procedure) and then moved to the set position of the recording medium 108 on the front side (10th procedure). This printing execution process procedure is not executed when the occurrence of jam is detected. When performing N times overprinting, the 5th to 8th steps are repeated N times, and when the N times printing is completed, the 9th to 10th steps are executed to finish the printing. If a swelling due to liquid discharge is formed on the recording medium 108 or the recording medium 108 is deformed while the fifth to eighth steps are repeated N times, the recording medium 108 is in the middle of the 1st to Nth steps. May lead to jams.

By the way, since the position of the platen 2 when the platen 2 is moved directly under the optical detection means (light emitting element 3) during the print instruction process of FIG. 5B is fixed, the installation status of the recording medium 108 can be changed. Unless changed, the occurrence of jam will continue to be detected. Therefore, the function of the gap adjusting unit 210 is improved so that the occurrence of jam with the same result is not detected every time. That is, as described above, the CPU 202 in the control unit 200 and the print control unit 208 cooperate with each other, and when a jam is detected during the current printing, an instruction is given to the gap adjustment unit 210. This instruction is to change the gap so that jam does not occur at the next printing. That is, the measures to be taken in the case of performing as described with reference to FIGS. 1 (a) to 1 (c) or performing N times overprinting are as described with reference to FIG. As a result, it is possible to prevent the liquid discharge head 118 from colliding with the recording medium 108 and to avoid a state in which printing cannot be performed forever. Specifically, when instructing the gap adjusting unit 210 to change the gap, the basic operation is to automatically retry a plurality of N times until printing becomes possible. In addition, such a function can be paraphrased as an image forming method. In the control step, when the control means instructs the gap adjusting means in the gap adjusting step to change the gap, it corresponds to a processing process of automatically retrying a plurality of times until printing becomes possible.

FIG. 6 is a flowchart showing an operation process of adjusting the gap between the liquid discharge head 118 and the recording medium 108 by the control unit 200 of the liquid discharge unit described above. FIG. 6A is a flowchart showing an operation process when the Nth printing instruction is given, and FIG. 3B is an operation when the N + 1th printing instruction is given when the Nth printing is not executed. It is a flowchart which shows the process.

With reference to FIG. 6A, when the operation panel 213 is operated to give the Nth printing instruction (step S1), the gap between the liquid discharge head 118 and the recording medium 108 is automatically adjusted (step S2). ). After that, before the start of printing, the entire recording medium 108 is sensed by a sensor (optical detection means) (step S3), and then a jam (JAM) determination (step S4) is performed. As a result of this determination, if there is a concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that a jam (JAM) has occurred and printing is not executed (step S5), and the operation ends. On the other hand, if there is no concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that jam (JAM) does not occur. Therefore, after the start of printing (step S6) and the end of printing (step 7), the operation ends.

With reference to FIG. 6B, when the operation panel 213 is operated when the Nth printing is not executed and the N + 1th printing instruction (step S1) is given, the liquid discharge head 118 is automatically recorded. The gap with the medium 108 is adjusted (step S2). Here, the position of the recording medium 108 to be adjusted is shifted by a certain amount (constant interval) from the Nth time. After that, before the start of printing, the entire recording medium 108 is sensed by a sensor (optical detection means) (step S3), and then a jam (JAM) determination (step S4) is performed.

As a result of this determination, if there is a concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that a jam (JAM) has occurred and printing is not executed (step S5), and the operation ends. On the other hand, if there is no concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that jam (JAM) does not occur. Therefore, after the start of printing (step S6) and the end of printing (step 7), the operation ends. Here, when the recording medium 108 has irregularities, the position can be shifted by a certain interval to prevent the occurrence of jam (JAM) in the jam (JAM) determination (step S4). However, although it is not always possible to prevent the occurrence of jam (JAM), it is not determined when the gap is adjusted at the convex portion of the recording medium 108. In addition, such a function can be paraphrased as an image forming method. In the control step, when the control means instructs the gap adjusting means in the gap adjusting step to change the gap, it corresponds to a processing process in which the position of the recording medium is shifted by the gap adjusting means at regular intervals.

FIG. 7 is a flowchart showing an operation process of adjusting the gap between the liquid discharge head 118 and the recording medium 108 by the control unit 200 of the liquid discharge unit, which is the main part of the image forming apparatus according to the second embodiment. FIG. 3A is a flowchart showing an operation process when the Nth print instruction is given, and FIG. 3B is a flowchart when the N + 1th print instruction is given when the Nth print instruction is not executed. It is a flowchart which shows operation process. FIG. 3C is a flowchart showing an operation process when the N + 2nd print instruction is given when the Nth and N + 1th print instructions are not executed.

With reference to FIG. 7A, the operation processing when the Nth printing instruction is given is the same as that of the processing flow of FIG. 6A, and thus the description thereof will be omitted.

With reference to FIG. 7B, when the operation panel 213 is operated when the Nth printing is not executed and the N + 1th printing instruction (step S1) is given, the liquid discharge head 118 is automatically recorded. The gap with the medium 108 is adjusted (step S2). Here, the position of the recording medium 108 to be adjusted with the Nth time is shifted by a certain amount + direction + A. After that, before the start of printing, the entire recording medium 108 is sensed by a sensor (optical detection means) (step S3), and then a jam (JAM) determination (step S4) is performed. As a result of this determination, if there is a concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that a jam (JAM) has occurred and printing is not executed (step S5), and the operation ends. On the other hand, if there is no concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that jam (JAM) does not occur. Therefore, after the start of printing (step S6) and the end of printing (step 7), the operation ends.

With reference to FIG. 7C, when the operation panel 213 is operated when the N + 1th printing is not executed and the N + 2nd printing instruction (step S1) is given, the liquid discharge head 118 is automatically recorded. The gap with the medium 108 is adjusted (step S2). Here, the position of the recording medium 108 to be adjusted with the Nth time is shifted by a certain amount-direction by -2A. After that, before the start of printing, the entire recording medium 108 is sensed by a sensor (optical detection means) (step S3), and then a jam (JAM) determination (step S4) is performed.

As a result of this determination, if there is a concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that a jam (JAM) has occurred and printing is not executed (step S5), and the operation ends. On the other hand, if there is no concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that jam (JAM) does not occur. Therefore, after the start of printing (step S6) and the end of printing (step 7), the operation ends. Here, the position of the recording medium 108 whose gap has been adjusted in the Nth printing is shifted in the + − direction. At this time, if the recording medium 108 that is convex in the opposite direction when shifted by a certain amount in the same direction is targeted, the occurrence of jam (JAM) continues to be detected. Therefore, by shifting in the + -direction in order, it is possible to eliminate such concerns and prevent the occurrence of jam (JAM). In addition, such a function can be paraphrased as an image forming method. In the control step, when the control means instructs the gap adjusting means in the gap adjusting step to change the gap, it corresponds to a processing process in which the position of the recording medium is alternately shifted in the + direction and the − direction by the gap adjusting means.

FIG. 8 is a flowchart showing an operation process of adjusting the gap between the liquid discharge head and the recording medium 108 by the control unit 200 of the liquid discharge unit, which is the main part of the image forming apparatus according to the third embodiment. FIG. 3A is a flowchart showing an operation process when the Nth print instruction is given, and FIG. 3B is a flowchart when the N + 1th print instruction is given when the Nth print instruction is not executed. It is a flowchart which shows operation process.

With reference to FIG. 8A, the operation processing when the Nth printing instruction is given is the same as that of the processing flow of FIG. 6A, and thus the description thereof will be omitted.

With reference to FIG. 8B, when the operation panel 213 is operated when the Nth printing is not executed and the N + 1th printing instruction (step S1) is given, the liquid discharge head 118 is automatically recorded. The gap with the medium 108 is adjusted (step S2). Here, the position of the recording medium 108 to be adjusted is randomly shifted from the Nth time. After that, before the start of printing, the entire recording medium 108 is sensed by a sensor (optical detection means) (step S3), and then a jam (JAM) determination (step S4) is performed.

As a result of this determination, if there is a concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that a jam (JAM) has occurred and printing is not executed (step S5), and the operation ends. On the other hand, if there is no concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that jam (JAM) does not occur. Therefore, after the start of printing (step S6) and the end of printing (step 7), the operation ends. Here, since the unevenness of the recording medium 108 is not always periodic, the aim is to prevent the number of retries from becoming extremely large, for example, by randomly shifting using a random number. In addition, such a function can be paraphrased as an image forming method. In the control step, when the control means instructs the gap adjusting means in the gap adjusting step to change the gap, it corresponds to a processing process in which the position of the recording medium is randomly shifted by the gap adjusting means.

FIG. 9 shows an operation process when the Nth printing instruction for adjusting the gap between the liquid discharge head and the recording medium 108 is performed by the control unit 200 of the liquid discharge unit, which is the main part of the image forming apparatus according to the fourth embodiment. It is a flowchart which shows.

Referring to FIG. 9, when the operation panel 213 is operated to give the Nth printing instruction (step S1), the gap between the liquid discharge head 118 and the recording medium 108 is automatically adjusted (step S2). After that, before the start of printing, the entire recording medium 108 is sensed by a sensor (optical detection means) (step S3), and then a jam (JAM) determination (step S4) is performed.

As a result of this determination, if there is a concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that a jam (JAM) has occurred and printing is not executed (step S5). However, the gap between the liquid discharge head 118 and the recording medium 108 is automatically adjusted again without causing an error (step S6). That is, after shifting the position of the recording medium 108 to be adjusted, the process returns to before the previous automatic gap adjustment between the liquid discharge head 118 and the recording medium 108 (step S2), and the subsequent processing is repeated. On the other hand, as a result of the jam (JAM) determination (step S4), if there is no concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that the jam (JAM) does not occur. Therefore, after the start of printing (step S7) and the end of printing (step 8), the operation ends. Here, once the occurrence of jam (JAM) is detected, printing is not executed, but by shifting the position of the recording medium 108 again and automatically adjusting the gap, complicated operations by the user can be suppressed. Further, the automatic retry of the gap adjustment makes it possible to select ON / OFF on the printer driver 212 or the operation panel 213. In addition, such a function can be paraphrased as an image forming method. In the control step, it corresponds to a processing process in which the control means can select and perform a function of automatically retrying the gap change a plurality of times.

FIG. 10 is a flowchart showing an operation process of adjusting the gap between the liquid discharge head and the recording medium 108 by the control unit 200 of the liquid discharge unit, which is the main part of the image forming apparatus according to the fifth embodiment. FIG. 3A is a flowchart showing an operation process when the Nth printing instruction including printing overlap is performed, and FIG. 3B is a flowchart showing an operation process related to the Nth printing overlap.

With reference to FIG. 10A, the operation processing when the Nth printing instruction including the printing overlap is given is substantially the same as the case of the processing flow of FIG. 6A. However, here, as a result of the jam (JAM) determination (step S4), if it is considered that the jam (JAM) does not occur and printing is started (step S6), the process of overlapping printing is performed as the processing process A.

With reference to the process of overprinting in FIG. 10B, the control unit 200 first confirms that n = 1 (step S11) is set as the number of overprints, and then performs the nth overprinting (step S11). Step S12). After that, before the start of printing, the entire recording medium 108 is sensed by a sensor (optical detection means) (step S13), and then a jam (JAM) determination (step S14) is performed.

As a result of this determination, if there is a concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that a jam (JAM) has occurred, and the operation ends after the printing end (step S17). On the other hand, if there is no concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that jam (JAM) does not occur. Therefore, the gap between the liquid discharge head 118 and the recording medium 108 is adjusted by shifting the gap by a certain interval (step S15). After that, the process proceeds to the n = N determination (step 16) in which the printing overlap is continued and it is confirmed whether or not the number of printing layers n has reached N. As a result of this determination, if n = N, printing ends (step S17) and the operation ends. On the other hand, if n <N, the nth printing overlap is performed (step S12), and the subsequent processing is repeated.

Here, when printing is performed N times, the gap adjustment is performed so as to be shifted by a certain interval for each number of times of printing. As a result, even when the recording medium 108 is a T-shirt and a floating occurs, the gap can be adjusted appropriately and the occurrence of jam (JAM) can be prevented.

In addition, such a function can be paraphrased as an image forming method. In the control step, when the control means instructs the gap adjusting means in the gap adjusting step to change the gap, it corresponds to a processing process in which the gap adjusting means shifts the gap at regular intervals for each printing overlap.

By the way, when the control unit 200 instructs the gap adjusting unit 210 to change the gap, the gap adjusting unit 210 can select on the printer driver 212 or the operation panel 213 whether or not to shift each time the number of times of printing is repeated. .. Such a function can be paraphrased as an image forming method. In the control step, when the control means instructs the gap adjusting means in the gap adjusting step to change the gap, the gap adjusting means corresponds to a processing process in which it is possible to select whether or not to shift each printing overlap.

FIG. 11 is a flowchart showing an operation process of adjusting the gap between the liquid discharge head and the recording medium 108 by the control unit 200 of the liquid discharge unit, which is the main part of the image forming apparatus according to the sixth embodiment. FIG. 3A is a flowchart showing an operation process when the Nth printing instruction including printing overlap is performed, and FIG. 3B is a flowchart showing an operation process related to the Nth printing overlap.

With reference to FIG. 11 (a), the operation process when the Nth printing instruction including the print overlay is given is the same as the case of the process flow of FIG. 10 (a). Again, as a result of the jam (JAM) determination (step S4), when it is considered that the jam (JAM) does not occur and printing is started (step S6), the process of overlapping printing is performed as the processing process A.

With reference to the process of overprinting in FIG. 11B, the control unit 200 first confirms that n = 1 (step S21) is set as the number of overprints, and then performs the nth overprinting (step S21). Step S22). After that, before the start of printing, the entire recording medium 108 is sensed by a sensor (optical detection means) (step S23), and then a jam (JAM) determination (step S24) is performed.

As a result of this determination, if there is a concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that a jam (JAM) has occurred, and printing ends (step S27), and then the operation ends. On the other hand, if there is no concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that jam (JAM) does not occur. Therefore, with respect to the gap between the liquid discharge head 118 and the recording medium 108, the gap is adjusted by changing the amount of shift each time (step S25). After that, the process proceeds to the n = N determination (step 26) in which the printing overlap is continued and it is confirmed whether or not the printing overlap count n has reached N. As a result of this determination, if n = N, printing ends (step S27) and the operation ends. On the other hand, if n <N, the nth printing overlap is performed (step S22), and the subsequent processing is repeated.

Here, when printing is performed N times, the amount of shifting the gap adjustment is changed each time the printing is repeated. As a result, even when the recording medium 108 is a T-shirt and its floating changes, the gap adjustment can be appropriately performed and the occurrence of jam (JAM) can be prevented.

In addition, such a function can be paraphrased as an image forming method. In the control step, when the control means instructs the gap adjusting means to change the gap, it corresponds to a processing process in which the gap adjusting means changes the amount of shifting each time the number of times of printing is repeated.

Incidentally, also here, as in the case of the fifth embodiment, when the control unit 200 instructs the gap adjusting unit 210 to change the gap, the printer driver determines whether or not the gap adjusting unit 210 shifts each time by the number of times of printing. It can be selected on 212 or the operation panel 213. Such a function can be paraphrased as an image forming method, and is the same as in the case of the fifth embodiment.

FIG. 12 is a flowchart showing an operation process of adjusting the gap between the liquid discharge head and the recording medium 108 by the control unit of the liquid discharge unit, which is the main part of the image forming apparatus according to the seventh embodiment. FIG. 3A is a flowchart showing an operation process when the Nth printing instruction including printing overlap is performed, and FIG. 3B is a flowchart showing an operation process related to the Nth printing overlap.

With reference to FIG. 12A, the operation processing when the Nth printing instruction including the printing overlap is given is the same as the case of the processing flow of FIG. 10A. Again, as a result of the jam (JAM) determination (step S4), when it is considered that the jam (JAM) does not occur and printing is started (step S6), the process of overlapping printing is performed as the processing process A.

With reference to the process of overprinting in FIG. 12B, the control unit 200 first confirms that n = 1 (step S31) is set as the number of overprints, and then performs the nth overprinting (step S31). Step S32). After that, before the start of printing, the entire recording medium 108 is sensed by a sensor (optical detection means) (step S33), and then a jam (JAM) determination (step S34) is performed.

As a result of this determination, if there is a concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that a jam (JAM) has occurred, and printing ends (step S37), and then the operation ends. On the other hand, if there is no concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that jam (JAM) does not occur. Therefore, the gap between the liquid discharge head 118 and the recording medium 108 is adjusted (step S35) when a predetermined time has elapsed since the previous adjustment. After that, the process proceeds to the n = N determination (step 36) in which the printing overlap is continued and it is confirmed whether or not the printing overlap count n has reached N. As a result of this determination, if n = N, printing ends (step S37) and the operation ends. On the other hand, if n <N, the nth printing overlap is performed (step S32), and the subsequent processing is repeated.

Here, when printing is repeated N times, the gap adjustment is performed so as to be shifted at each time interval. As a result, even when the recording medium 108 is a T-shirt and the surface shape changes with the passage of time, the gap adjustment can be appropriately performed and the occurrence of jam (JAM) can be prevented.

In addition, such a function can be paraphrased as an image forming method. In the control step, when the control means instructs the gap adjusting means to change the gap, it corresponds to a processing process in which the gap adjusting means shifts the gap at each time interval.

FIG. 13 is a flowchart showing an operation process of adjusting the gap between the liquid discharge head and the recording medium 108 by the control unit of the liquid discharge unit, which is the main part of the image forming apparatus according to the eighth embodiment. FIG. 3A is a flowchart showing an operation process when the Nth printing instruction including printing overlap is performed, and FIG. 3B is a flowchart showing an operation process related to the Nth printing overlap.

With reference to FIG. 13A, the operation processing when the Nth printing instruction including the printing overlap is given is the same as the case of the processing flow of FIG. 10A. Again, as a result of the jam (JAM) determination (step S4), when it is considered that the jam (JAM) does not occur and printing is started (step S6), the process of overlapping printing is performed as the processing process A.

With reference to the process of overprinting in FIG. 13B, the control unit 200 first confirms that n = 1 (step S41) is set as the number of overprints, and then performs the nth overprinting (step S41). Step S42). After that, before the start of printing, the entire recording medium 108 is sensed by a sensor (optical detection means) (step S43), and then a jam (JAM) determination (step S44) is performed.

As a result of this determination, if there is a concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that a jam (JAM) has occurred, and printing ends (step S47), and then the operation ends. On the other hand, if there is no concern that the liquid discharge head 118 and the recording medium 108 collide with each other, it is considered that jam (JAM) does not occur. Therefore, the gap between the liquid discharge head 118 and the recording medium 108 is adjusted so as to change the amount of shift according to, for example, temperature and humidity as the environment (step S45). After that, the process proceeds to the n = N determination (step 46) in which the printing overlap is continued and it is confirmed whether or not the printing overlap count n has reached N. As a result of this determination, if n = N, printing ends (step S47) and the operation ends. On the other hand, if n <N, the nth printing overlap is performed (step S42), and the subsequent processing is repeated.

Here, when printing is repeated N times, the gap adjustment is performed so as to change the amount of shift according to the temperature and humidity. As a result, even when the recording medium 108 is a T-shirt and the surface shape changes due to the temperature and humidity environment, the gap can be adjusted appropriately and the occurrence of jam (JAM) can be prevented. ..

In addition, such a function can be paraphrased as an image forming method. In the control step, when the control means instructs the gap adjusting means to change the gap, it corresponds to a processing process in which the gap adjusting means changes the amount of shift according to the environment.

Incidentally, the presence or absence of the gap adjustment at the time of N times printing overlap described in Examples 5 to 8 makes it possible to select ON / OFF on the printer driver 212 and the operation panel 213. Further, in each of the above-described embodiments, the T-shirts are assumed to be applied as the recording media 1, 1', 11 and 108, but other objects can also be applied. For example, general paper, coated paper, label paper, overhead projector sheet, film, flexible thin plate and the like can be exemplified.

1, 1', 11, 108 Recording medium 2 Platen 3 Light emitting element 4 Light receiving element 5, 5'Printing unit 100 Carriage 101 Conveyance belt 102, 114 Timing belt 103 Encoder scale 104 Slide rail 105 Main scanning motor 106 Drive pulley 107 Driven pulley 109 Conveyor roller 110 Tension roller 111 Sub-scanning motor 112 Conveyance drive pulley 113 Conveyor roller pulley 115 Encoder wheel 116, 117 Encoder sensor 118 Liquid discharge head 119 Head driver 120 Linear encoder 121 Platen elevating motor 200 Control unit 201 Host interface (I / F)
202 CPU
203 ROM
204 RAM
205 NVRAM
206 ASIC
207 Input / output (I / 0) unit 208 Print control unit 209 Main scanning motor drive unit 210 Gap adjustment unit 211 Sub-scanning motor drive unit 212 Printer driver 213 Operation panel Δh, Δh ′ Gap

Japanese Patent No. 5425609

Claims (20)

A transport means for transporting a recording medium, a carriage for printing on the recording medium conveyed by the transport means with a liquid discharge head, and a gap adjusting means for adjusting a gap between the recording medium and the liquid discharge head. A jam detecting means for detecting whether or not the liquid discharge head and the recording medium collide with each other in the gap adjusted by the gap adjusting means to cause a jam from the entire recording medium before printing, and the jam detection means. In an image forming apparatus including a control means for controlling printing to be stopped when a jam is detected by the means.
Wherein, when the jam is detected by the jam detecting means, when in the instruction to the gap adjusting means such that the gap does not occur the jamming at the next printing to set for changing the gap, An image forming apparatus characterized in that the position of the recording medium is randomly shifted by the gap adjusting means. When the control means instructs the gap adjusting means to change the gap, the control means automatically retries a plurality of times until printing becomes possible .
The image forming apparatus according to claim 1. The control means can select a function of automatically retrying the change of the gap a plurality of times .
The image forming apparatus according to claim 2. The control means instructs the recording medium to perform printing overlaps for printing twice or more, and as the number of times of printing overlaps during the printing overlaps, the control means instructs the gap adjusting means to instruct the recording medium and the liquid. Change so that the gap with the discharge head widens ,
The image forming apparatus according to claim 1. When the control means instructs the gap adjusting means to change the gap, the control means shifts the gap by the gap adjusting means at regular intervals for each number of times of printing.
The image forming apparatus according to claim 4. When the control means instructs the gap adjusting means to change the gap, the gap adjusting means changes the amount of shifting each time the number of times of printing is repeated.
The image forming apparatus according to claim 4. When the control means instructs the gap adjusting means to change the gap, the control means shifts the gap at each time interval by the gap adjusting means.
The image forming apparatus according to claim 4. When the control means instructs the gap adjusting means to change the gap, the control means changes the amount of shift according to the environment.
The image forming apparatus according to any one of claims 4 to 7. The environment is temperature or humidity,
The image forming apparatus according to claim 8. When the control means instructs the gap adjusting means to change the gap, the gap adjusting means can select whether or not to shift each time the number of times of printing is repeated .
The image forming apparatus according to claim 5 or 6. A transport step in which the transport means conveys the recording medium, a printing step in which printing is performed using the liquid discharge head built into the recording medium whose carriage is conveyed in the transfer step, and a gap adjusting means is the recording medium. Whether or not the liquid discharge head and the recording medium collide with each other in the gap adjusting step for adjusting the gap with the liquid discharge head and the gap adjusted by the jam detecting means in the gap adjusting step to cause jam. In an image forming method having a jam detection step of detecting from the entire recording medium before printing, and a control step of controlling means to stop printing when a jam is detected in the jam detection step.
In the control step, when a jam is detected in the jam detection step during the current printing, the control means moves to the gap adjusting means in the gap adjusting step so that the gap does not cause the jam in the next printing. An image forming method characterized in that the position of the recording medium is randomly shifted by the gap adjusting means when an instruction is given to make a setting for changing the gap. In the control step, when the control means instructs the gap adjusting means in the gap adjusting step to change the gap, the control means automatically retries a plurality of times until printing becomes possible .
The image forming method according to claim 11. In the control step, the control means can select and perform the function of automatically retrying the change of the gap a plurality of times .
The image forming method according to claim 12. In the control step, the control means commands print stacking for printing on the recording medium two or more times, and as the number of print stacks overlaps during the print stacking, the gap adjusting means in the gap adjusting step To widen the gap between the recording medium and the liquid discharge head .
The image forming method according to claim 11. In the control step, when the control means instructs the gap adjusting means in the gap adjusting step to change the gap, the gap adjusting means shifts the gap at regular intervals for each number of times of printing.
The image forming method according to claim 14. In the control step, when the control means instructs the gap adjusting means in the gap adjusting step to change the gap, the gap adjusting means changes the amount of shifting each time the number of times of printing is repeated.
The image forming method according to claim 14. In the control step, when the control means instructs the gap adjusting means in the gap adjusting step to change the gap, the gap adjusting means shifts the gap at each time interval.
The image forming method according to claim 14. In the control step, when the control means instructs the gap adjusting means in the gap adjusting step to change the gap, the amount of shifting is changed according to the environment .
The image forming method according to any one of claims 14 to 17. Let the temperature or humidity be the environment in the control step .
The image forming method according to claim 18. In the control step, when the control means instructs the gap adjusting means in the gap adjusting step to change the gap, the gap adjusting means can select whether or not to shift each printing stacking number. to,
The image forming method according to claim 15 or 16.