JP2015150719A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device which can secure a region required for printing on the basis of print data by suppressing the change of a region where preliminary discharge is performed in printing on a printed matter that is transferred.SOLUTION: An image formation device having transfer means and performing printing on a printed matter 400 that is transferred by the transfer means, includes: printing means which has a print head that can discharge an ink in a direction orthogonal to the transfer direction of the printed matter 400 and discharges the ink toward the printed matter 400; and preliminary discharge control means which calculates a required preliminary discharge region 420 in advance when preliminary discharge not contributing to image formation is performed from the print head, and controls transfer speed of the printed matter 400 in accordance with the calculated preliminary discharge region 420.

Description

  The present invention relates to an image forming apparatus.

  An ink jet recording apparatus is known as an image forming apparatus. The ink jet recording apparatus uses, for example, a recording head in which an ink liquid chamber and a nozzle communicating with the ink liquid chamber are formed, and applies pressure to the ink in the ink liquid chamber according to image information, thereby ejecting ink droplets to the nozzle. It is printed by flying from the surface and adhering to the substrate.

As a problem that such an ink jet recording apparatus has, there is a problem of nozzle drying.
Inkjet recording devices capping the nozzle surface while printing is in progress to suppress drying of the nozzle surface, but the printing head is on the recording medium while printing is in progress, so the nozzle surface is dry. Will progress. As the drying state progresses, the ink viscosity increases and ink ejection defects such as omission and bending tend to occur, causing image defects.
Therefore, in the ink jet recording apparatus, a maintenance area is provided in the apparatus main body in order to maintain / recover the ejection performance (hereinafter also referred to as nozzle state) of the recording head. By maintaining the recording head in this maintenance area and performing various maintenance processes, the nozzle state is maintained / recovered.

  However, the print throughput decreases depending on the time required to move the recording head to the maintenance area and the time required for the maintenance process itself. In addition, in the maintenance process, the thick ink is discarded in the waste ink receiver in the device. Therefore, the greater the number of maintenance times, the earlier the time when the waste ink receiver is full will shorten the life of the device. become.

In order to solve such a problem, a technique for performing “preliminary discharge” (also referred to as “empty discharge”, “purge”, or the like) for discharging ink not intended for image recording onto a printing material is known.
Regarding the implementation of preliminary ejection, there is a technique for determining whether or not to perform preliminary ejection based on the relationship between the time from the last driving of the print head until the preliminary ejection is performed and the time until the next printing is performed. It is known (see, for example, Patent Document 1).

  In Patent Document 1, for the purpose of reliably recovering the nozzle and suppressing the consumption of ink by the recovery operation, the preliminary ejection timing and the printing timing are predicted, and the time from the preliminary ejection timing to the printing timing is a fixed time. In the following cases, a configuration in which preliminary ejection is not performed is disclosed.

In the ink jet printing, printing is performed without touching the printing object, so printing can be performed while the printing object is moving, and printing on a three-dimensional printing object is also possible.
In an apparatus that performs printing while conveying a printing material by a conveying means (conveying belt) such as a belt conveyor, an area in which preliminary ejection is performed is controlled in order to perform printing correctly at a predetermined position on the printing material. There is a need.

However, when preliminary ejection is performed on a substrate while operating the substrate, if the amount of ink ejected is different, the size of the region where preliminary ejection is performed changes, and the printable region is limited accordingly. There was a problem of being.
The amount of ink ejected from the nozzle in the preliminary ejection and the amount of ejection per unit time easily change due to the temperature and humidity in the vicinity of the print head, so that the amount of ejection is constant. It is difficult to control. That is, it is difficult to control the ink discharge amount so that the preliminary discharge region is within a predetermined range.

  Accordingly, in view of the above problems, the present invention provides an image forming apparatus capable of suppressing a change in a region in which preliminary ejection is performed and ensuring a region necessary for printing based on print data in printing on a conveyed printing material. The purpose is to do.

  In order to solve the above-described problems, an image forming apparatus according to the present invention includes a conveying unit, and in the image forming apparatus that performs printing on a printed material conveyed by the conveying unit, the conveying direction of the printed material. Having a print head capable of ejecting ink in a direction perpendicular to the print medium, a printing unit for ejecting ink toward the substrate, and a preliminary ejection required when performing preliminary ejection that does not contribute to image formation from the print head An image forming apparatus comprising: a preliminary discharge control unit configured to calculate a region in advance and control a conveyance speed of the printing material according to the calculated preliminary discharge region.

  According to the image forming apparatus of the present invention, it is possible to provide an image forming apparatus capable of securing a necessary area for printing based on print data by suppressing a change in an area in which preliminary ejection is performed in printing on a substrate to be conveyed. can do.

1 is a perspective view illustrating an example of an overall configuration of an image forming apparatus according to an exemplary embodiment. 1 is a perspective view illustrating an example of a main configuration of an image forming apparatus according to an exemplary embodiment. 2 is a block diagram illustrating an example of a configuration of a control unit and peripheral devices of the image forming apparatus according to the present exemplary embodiment. FIG. It is explanatory drawing which shows typically the printing operation | movement with respect to the to-be-printed material of the image forming apparatus of this embodiment. It is explanatory drawing which shows a preliminary discharge and printing discharge typically. It is explanatory drawing which shows the difference of the preliminary discharge area | region by temperature typically. It is a flowchart which shows the flow of control of the conveyance speed in preliminary discharge. It is a flowchart which shows the flow of control of the conveyance speed in preliminary discharge.

  Hereinafter, an image forming apparatus according to the present invention will be described with reference to the drawings. It should be noted that the present invention is not limited to the embodiments of the examples shown below, and other embodiments, additions, modifications, deletions, and the like can be changed within a range that can be conceived by those skilled in the art. Any aspect is included in the scope of the present invention as long as the operations and effects of the present invention are exhibited.

FIG. 1 shows the overall configuration of the image forming apparatus of the present embodiment, and FIG.
The image forming apparatus according to the present embodiment is an image forming apparatus that includes a transport unit 100 such as a belt conveyor, and performs printing on a printed material transported by the transport unit 100, and includes a transport direction of the printed material. A print head 209 having a print head 209 capable of ejecting ink in an orthogonal direction and ejecting ink toward the substrate to be printed, and when performing preliminary ejection that does not contribute to image formation from the print head, A preliminary ejection control unit that calculates a preliminary ejection area to be performed in advance and controls a conveyance speed of the printing material according to the calculated preliminary ejection area.

  In the present embodiment, examples of the printed material include printed materials having a three-dimensional shape such as a box, and examples thereof include cardboard boxes and various packaging materials such as foods and miscellaneous goods.

  The image forming apparatus according to the present embodiment is further provided with a position adjusting unit 103 capable of adjusting a conveyance trajectory of the printed material, and an upstream side of the printing unit 101 in the conveyance direction of the printed material, A printing distance detection unit 102 that detects a vertical distance between a printing surface of a printed matter and an ink discharge surface of the printing unit 101 is provided.

  As shown in FIG. 2, the position adjusting unit 103 is in contact with the receiver 212 that receives the output signal of the optical sensor (printing distance detecting unit 102) and the substrate to be printed on the conveying unit 100, and the track of the substrate to be printed. Is changed to have a roller 211 that corrects the position of the printing surface.

The printing unit 101 is attached to the side of the conveying unit 100 through a protective wall 105. As a printing operation of the printing unit 101, for example, ink is supplied from an ink cartridge 205, which is a main tank of ink, to a sub tank disposed in the carriage 200, and a print head 209 mounted on the carriage 200 is applied to a printing object. Ink is ejected to print a predetermined image. The carriage 200 on which the print head 209 and the ink tank are mounted is movable in the main scanning direction, which is the conveyance direction of the printing object, and in the sub-scanning direction, which is a direction orthogonal to the conveyance direction.
The printing unit 101 is not limited to this configuration. For example, the main tank and the sub tank may be integrated.

  The maintenance unit (maintenance unit) 201 is used to recover the printing performance of the ink ejection surface (nozzle surface) of the print head 209. The waste ink box 204 is provided to store ink ejected when maintenance is performed.

  A PSU 202 is a main power supply unit of the printing unit 101 and enables power on / off control.

The printing unit 101 includes a motor 208, a main scanning direction movable unit 207 that moves the carriage in the main scanning direction by driving the motor, and a sub scanning direction movable unit 206 that moves the carriage in the sub scanning direction.
The printing operation in the image forming apparatus according to the present embodiment is performed at a fixed position on the conveyance path along the conveyance unit 100. However, the carriage 200 can move in the main scanning direction and the sub-scanning direction for printing. Is possible.

  The CTL board 203 is a control unit, and includes control means for performing control for changing printing conditions such as drive control of the motor 208 and drive control of the roller 211 as well as control such as maintenance of the carriage 200.

FIG. 3 is a block diagram showing the configuration of the control means and peripheral devices mounted on the CTL board 203.
As shown in FIG. 3, the control unit 300 includes a CPU 301 that controls the entire image forming apparatus such as print control, motor drive control, and maintenance / supply control, and a ROM 302 that stores programs executed by the CPU 301 and other fixed data. A RAM 303 for temporarily storing image data, a rewritable non-volatile memory (NVRAM) 304 for retaining data even while the apparatus is powered off, various signal processing for image data, rearrangement, etc. And an ASIC 306 for processing input / output signals for controlling the entire apparatus.

  The control unit 300 generates a drive waveform for driving the print head 209, and also outputs a print control unit 309 that outputs image data for selectively driving the pressure generation unit of the print head 209 and various data associated therewith to the head driver 312. I have.

In addition, the motor control unit 310 for controlling the movement of the carriage 200 in the main scanning direction and the sub-scanning direction, the roller control unit 318 for controlling the roller 211 for adjusting the transport path of the printing object, and the printing target A conveyance speed control unit (not shown) for controlling the conveyance speed of the object is provided.
The conveyance speed control unit controls the conveyance speed at the time of preliminary ejection by an input from preliminary ejection control means (not shown). Preliminary ejection control means calculates a preliminary ejection area in advance, and controls the conveyance speed of the printed material according to the calculated preliminary ejection area.

The control unit 300 includes information on temperature and humidity in the apparatus from the temperature sensor and humidity sensor 319, detection pulses from the linear encoder 316, detection signals from the printing object detection sensor 315, printing surface and printing of the printing object. An I / O 307 to which signals from various sensors such as a detection signal from a printing distance detection unit 102 that detects a vertical distance from the ink ejection surface of the unit 101 is input is provided.
The control unit 300 is connected to an operation panel 314 (display unit) for inputting and displaying information necessary for the apparatus.

  The control unit 300 includes a host I / F 305 for transmitting and receiving data and signals to and from the host side. For example, print data or the like generated by a printer driver 317 of a host device (information processing device, external device) such as an information processing device such as a personal computer, an image reading device such as an image scanner, or an imaging device such as a digital camera, is connected to a cable or Received by the host I / F 305 via the network.

  Then, the CPU 301 of the control unit 300 reads and analyzes the print data in the reception buffer included in the host I / F 305, performs necessary image processing, data rearrangement processing, and the like in the ASIC 306, and sends it to the print control unit 309. Forward. Also, image data and drive waveforms are output from the print control unit 309 to the head driver 312 at a required timing.

  For example, even when font data is stored in the ROM 302, the dot pattern data for image output is generated by the printer driver 317 on the host side and converted into bitmap data and transferred to the image forming apparatus. You may make it do.

  A drive waveform generation unit (not shown) of the print control unit 309 includes a D / A converter that performs D / A conversion on drive pulse pattern data stored in the ROM 302 and read out by the CPU 301, an amplifier, and the like. In addition, a drive waveform composed of one drive pulse or a plurality of drive pulses is output to the head driver 312.

The head driver 312 is a drive pulse that forms a drive waveform provided from the drive waveform generation unit of the print control unit 309 based on image data (dot pattern data) corresponding to one line of the print head 209 that is input serially. Is selectively applied to the pressure generating means of the print head 209 to drive the print head 209.
The head driver 312 has, for example, a shift register that inputs serial data that is a clock signal and image data, a latch circuit that latches a register value of the shift register using a latch signal, and an output value of the latch circuit that changes the level. A level conversion circuit (level shifter) and an analog switch array (switch means) whose on / off is controlled by this level shifter, etc., and the required drive pulse included in the drive waveform by controlling the on / off of the analog switch array Is selectively applied to the pressure generating means of the print head 209.

The printing operation for the printing material of the image forming apparatus according to the present embodiment will be described with reference to FIGS.
FIG. 4A is a diagram illustrating a state before printing on the printing object 400.
When the printing object 400 reaches the position of the printing distance detection unit 102 by the conveying unit 100, the printing distance detection unit 102 measures the vertical distance between the printing surface of the printing object 400 and the ink ejection surface of the printing unit 101. .
When the value of the vertical distance detected by the printing distance detection unit 102 is different from the value of the printing distance set in advance, printing is performed by the control unit (the control unit 300 shown in FIG. 3) based on the measured vertical distance value. Control is performed to change the condition.

FIG. 4B is a diagram illustrating a state where printing is performed on the printing object 400.
The printing unit 101 appropriately changes the printing conditions based on the value of the vertical distance measured as described with reference to FIG. 4A, and prints the image 401 on the printing surface.

FIG. 4C is a diagram illustrating a state after printing is performed on the printing object 400.
The printing object 400 shown on the downstream side in the transport direction (the right side in the figure) has completed the printing of the image 401. Subsequently, a process similar to that shown in FIGS. 4A and 4B is performed on the next print substrate 400 conveyed from the upstream side in the conveyance direction (left side in the drawing).

FIG. 5 is an explanatory diagram schematically showing preliminary discharge and print discharge.
As shown by the head driving waveform at the bottom of the figure, preliminary ejection is performed before printing based on the print data. As a result, as shown in the upper part of the figure, an area 420 where preliminary ejection is performed is formed before the area 410 where printing is performed based on the print data on the printing surface of the conveyed printing material 400. .

FIG. 6 is an explanatory diagram schematically showing the difference in the preliminary ejection area due to the temperature difference inside the apparatus (near the print head).
When the temperature inside the apparatus is 15 ° C. or higher in FIG. 6A, FIG. 6B is 10 to 15 ° C., FIG. 6C is 5 to 10 ° C., FIG. The example in the case of 0-5 degreeC is each shown. In addition, the conveyance speed of the printed material in FIGS.

  As shown in FIG. 6D, in a low temperature environment of about 0 to 5 ° C., the area where the preliminary ejection is performed becomes large, so the area 410 where printing based on the print data is performed is narrowed, and the print data is reduced. There may be a portion that is not printed. In such a case, in order to secure an area where printing is performed based on the print data, the transport speed of the printing object 400 is controlled by the preliminary discharge control means.

FIG. 7 is a flowchart illustrating an example of the control of the conveyance speed of the print substrate 400 by the preliminary ejection control unit in the image forming apparatus of the present embodiment.
First, the front end of the substrate 400 is detected (S001), and the temperature inside the apparatus, preferably the temperature near the print head 209 is acquired (S002).

Next, based on the temperature acquired in step S002, the amount of preliminary discharge is determined (S003). As a method for determining the ejection amount, for example, there is a method in which the correlation between the temperature and the number of ejected ink droplets is stored in advance as a table, and the number of droplets is determined based on this. Further, a method using a calculation formula that can be calculated may be used.
Note that the discharge amount of the preliminary discharge may be determined in consideration of the humidity. In this case, the humidity is also acquired in step S002.

Next, the necessary preliminary discharge area 420 is calculated based on the preliminary discharge amount determined in step S003 (S004).
The preliminary ejection control unit calculates the preliminary ejection area 420 based on the ink ejection amount in the preliminary ejection and the conveyance speed of the printing material 400. Specifically, the length of the preliminary ejection region 420 in the transport direction is calculated by the following formula.
Preliminary ejection area length (mm) = preliminary ejection volume (number of droplets) x ejection time per droplet (seconds) x transport speed of printed material (mm / sec)

  It is determined whether or not the calculated preliminary ejection area 420 exceeds a predetermined threshold (S005). If it exceeds, a transport speed that does not exceed the predetermined threshold is calculated (S006), and the calculated transport speed is calculated. (S007). Then, preliminary ejection is executed at the changed transport speed (S008).

In step S006, the conveyance speed is calculated by the following equation.
Conveyance speed of printed material (mm / second) = desired preliminary discharge area length (mm) / preliminary discharge amount (number of drops) × discharge time per second (second)

  If the length of the preliminary ejection area 420 calculated in step S004 does not exceed the predetermined threshold, preliminary ejection is executed without changing the transport speed (S008).

  Note that the preliminary ejection region 420 can always be made to have a constant length by resetting the conveyance speed in steps S006 and S007 in all cases without performing the determination in step S005.

  In addition, the preliminary ejection control unit can reduce the preliminary ejection area 420 by reducing the transport speed of the substrate 400 when the calculated preliminary ejection area 420 exceeds a predetermined threshold, The preliminary discharge area 420 can be minimized by stopping the conveyance speed of the object 400.

FIG. 8 is a flowchart illustrating another example of the control of the conveyance speed of the print substrate 400 by the preliminary ejection control unit in the image forming apparatus of the present embodiment.
In the present embodiment, the preliminary ejection control means includes means for calculating a margin area on the printing surface of the printing object 400 from the printing data.
First, the front end of the printing object 400 is detected (S101), and the temperature inside the apparatus, preferably the temperature near the print head 209 is acquired (S102).

Next, based on the temperature acquired in step S102, the amount of preliminary discharge is determined (S103). As a method for determining the ejection amount, for example, there is a method in which the correlation between the temperature and the number of ejected ink droplets is stored in advance as a table, and the number of droplets is determined based on this. Further, a method using a calculation formula that can be calculated may be used.
In addition, the discharge amount of the preliminary discharge may be determined in consideration of the humidity. In this case, the humidity is also acquired in step S102.

Next, the necessary preliminary discharge area 420 is calculated based on the preliminary discharge amount determined in step S103 (S104).
The preliminary ejection control unit calculates the preliminary ejection area 420 based on the ink ejection amount in the preliminary ejection and the conveyance speed of the printing material 400. Specifically, the length of the preliminary ejection region 420 in the transport direction is calculated by the following formula.
Preliminary ejection area length (mm) = preliminary ejection volume (number of droplets) x ejection time per droplet (seconds) x transport speed of printed material (mm / sec)

Next, the margin area of the printing surface of the printing material 400 is calculated from the printing data (S105). The margin area is an area excluding the print area 410 where the print data is printed on the printing surface.
It is determined whether or not the preliminary ejection area 420 calculated in step S104 exceeds the margin area calculated in step S105 (S106). If it exceeds, the conveyance speed that does not exceed the margin area is calculated (S107). ) And change to the calculated transport speed (S108). Then, preliminary ejection is executed at the changed transport speed (S109).

In step S107, the conveyance speed is calculated by the following equation.
Conveyance speed of printed material (mm / second) = desired preliminary discharge area length (mm) / preliminary discharge amount (number of drops) × discharge time per second (second)

  If the length of the preliminary ejection area 420 calculated in step S104 does not exceed the blank area, preliminary ejection is executed without changing the transport speed (S109).

  In the control example of the present embodiment, it is possible to suppress the frequency at which the conveyance speed of the print substrate 400 is reduced as compared with the control example illustrated in FIG.

  Note that the preliminary ejection region 420 can always be set to a certain length by resetting the transport speed in steps S107 and S108 in all cases without performing the determination in step S106.

  In addition, the preliminary ejection control unit can reduce the preliminary ejection area 420 by reducing the conveyance speed of the printing object 400 when the calculated preliminary ejection area 420 exceeds the blank area, and the printing object can be reduced. By stopping the conveyance speed of 400, the preliminary ejection area 420 can be minimized.

DESCRIPTION OF SYMBOLS 100 Conveyance means 101 Printing means 102 Printing distance detection means 103 Position adjustment means 200 Carriage 206 Sub-scanning direction movable part 208 Motor 209 Print head 211 Roller 300 Control means (control part)
400 Printed object 410 Print area 420 Pre-discharge area

Japanese Patent No. 3909714

Claims (8)

In an image forming apparatus that includes a transport unit and performs printing on a printing material transported by the transport unit.
A printing unit having a print head capable of ejecting ink in a direction orthogonal to the conveyance direction of the substrate, and ejecting ink toward the substrate;
A preliminary ejection control means for preliminarily calculating a necessary preliminary ejection area when performing preliminary ejection that does not contribute to image formation from the print head, and controlling a conveyance speed of the printing object according to the calculated preliminary ejection area; An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the preliminary ejection control unit calculates a preliminary ejection area based on an ink ejection amount in the preliminary ejection and a conveyance speed of the printing material.   3. The image forming apparatus according to claim 1, wherein the preliminary ejection control unit changes a conveyance speed of the printing material when the calculated preliminary ejection area exceeds a predetermined threshold. 4.   The preliminary ejection control unit calculates a conveyance speed of the printing object so that the preliminary ejection area does not exceed a predetermined threshold when the calculated preliminary ejection area exceeds a predetermined threshold; The image forming apparatus according to claim 3, wherein the image forming apparatus is changed to the calculated conveyance speed.   The image forming apparatus according to claim 3, wherein the preliminary ejection control unit decelerates or stops the conveyance speed of the printing material when the calculated preliminary ejection area exceeds a predetermined threshold. Means for calculating a margin area of a printing surface of the printing material from printing data;
3. The image forming apparatus according to claim 1, wherein the preliminary ejection control unit changes a conveyance speed of the printing object when the calculated preliminary ejection area exceeds the margin area.   The preliminary ejection control unit calculates a conveyance speed of the printing material so that the preliminary ejection area does not exceed the margin area when the calculated preliminary ejection area exceeds the margin area; The image forming apparatus according to claim 6, wherein the image forming apparatus is changed to the calculated conveyance speed.   The image forming apparatus according to claim 6, wherein the preliminary ejection control unit decelerates or stops the conveyance speed of the printed material when the preliminary ejection area exceeds the margin area.