JP2003200567A - Inkjet recording device - Google Patents

Abstract

(57) [Problem] To provide an ink jet recording apparatus in which an impact position of an ink droplet does not shift even on a printing surface having warpage or undulation. SOLUTION: In an ink jet recording apparatus, when a carriage 11 scans in a main scanning direction, the recording head 1 moves while the recording head 16 moves in the main scanning direction.
The sensor 160 measures the relative distance between the substrate 6 and the upper surface 20 of the substrate 2, and based on the measurement result, the control unit 60 drives and controls the actuator 170 to adjust the height position of the recording head 16. As a result, the relative distance between the recording head 16 and the printing surface can be kept constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording device.

[0002]

2. Description of the Related Art In an on-demand type ink jet recording apparatus, an ink droplet is ejected toward a recording sheet while a recording head moves on a guide extending in a main scanning direction to perform printing on the recording sheet. Here, there is usually a gap of about 0.5 mm between the recording head and the printing surface, and ink droplets ejected from the nozzle openings of the recording head fly through this gap and land on the surface of the recording paper. .

However, even when ink droplets are ejected from the recording head, the recording head is not stopped, but the carriage on which the recording head is mounted is moving on the guide in the main scanning direction. Here, there is a limit to the ink ejection response, and for example, with a response of 9 kHz, the resolution is 360 dpi.
(360 pieces per inch, that is, 70 μm), the moving speed V is V = 0.07 × 9000 = 630 mm / s. The ink ejection speed is 1 compared to this movement speed.
Even if it is about 0 times, as shown in FIGS. 6A and 6B, the ink droplets are ejected obliquely at an angle of several degrees. Here, FIG. 6A shows a state in which the ejected ink droplets land on the surface of the recording sheet while the recording head is moving to the right in the drawing.
FIG. 6B shows a state in which the ejected ink droplets land on the surface of the recording sheet while the recording head is moving to the left in the drawing. When the printing speed is increased by performing the bidirectional printing without considering the occurrence of such a state, even if ink droplets are ejected from the same nozzle opening at the same head position, as shown in FIG. , The landing position of the ink droplet is different between the ink droplet ejected when the recording head is moving to the right toward the drawing and the ink droplet ejected when the recording head is moving toward the left toward the drawing. Only the dimension a shifts in the main scanning direction.

Therefore, conventionally, the deviation of the landing position is canceled by correcting the timing of ejecting ink droplets in accordance with the moving direction of the recording head. Therefore, even if bidirectional printing is performed, the lines printed in the sub-scanning direction are connected.

[0005]

However, in the case of printing on a recording sheet or the like running on the platen, it can be dealt with only by such correction, but when a substrate or a panel is an object to be printed. In many cases, the distance between the recording head and the surface to be printed varies due to warping or waviness of these materials. In such a case, the lines extending in the sub-scanning direction cannot be connected neatly by the above correction alone. That is, when the position of the printed material changes from the position shown by the solid line in FIG. 7 to the position shown by the dotted line, the landing position of the ink droplet deviates greatly from the dimension b, and when bidirectional printing is performed, the position in the sub-scanning direction is increased. The lines that extend do not connect.

Therefore, a method of canceling the deviation of the landing position by correcting the timing of ejecting ink droplets is conceivable, as in the method capable of bidirectional printing on a recording sheet. However, there is a problem in that it is too late in terms of data processing to shift the timing at which the drive pulse is output so as to cancel the variation in the distance between the recording head and the printing surface. In addition, the software for printing needs to be recreated significantly, so it is not an easy method.

On the other hand, in the on-demand type ink jet, a multi-nozzle type is used in order to increase the printing speed, but even in this case, the position of the nozzle opening cannot be narrowed to 70 μm intervals in accordance with the resolution of 360 dpi. Therefore, as shown in FIG. 8, a large number of nozzle openings lined up in six rows are formed in the recording head at positions separated in the main scanning direction, and the positions of these nozzle openings are directed between the rows in the sub scanning direction. Are slightly shifted. Therefore, a line extending in the sub-scanning direction can be drawn by adjusting the timing of ejecting ink droplets from each nozzle opening as the print head moves in the main scanning direction. However, even in such a recording head, since each point forming one line is composed of an ink droplet ejected from a nozzle opening located at a position several mm apart in the main scanning direction, If the distance between the print head and the surface to be printed changes while the print head moves, the same problem as when attempting bidirectional printing (the ink droplet landing position is the main There is a problem that lines that are displaced in the scanning direction and extend in the sub-scanning direction are not connected.

In view of the above problems, the object of the present invention is to:
An object of the present invention is to provide an ink jet recording apparatus in which the landing positions of ink droplets do not shift even on the printed surface having warpage or waviness.

[0009]

An ink jet recording apparatus of the present invention is an ink jet recording apparatus having a head which moves according to a guide, and a distance measuring means for measuring a relative distance between the head and the surface to be printed. An actuator that changes the relative distance between the head and the print surface, and a spacing that adjusts the relative distance between the head and the print surface by driving and controlling the actuator based on the measurement result by the distance measuring unit. Distance control means, and when the head or the surface to be printed is scanned, the relative distance between the head and the surface to be printed is adjusted by the separation distance control means.

[0010]

DETAILED DESCRIPTION OF THE INVENTION An ink jet recording apparatus to which the present invention is applied will be described with reference to the drawings.

(Overall Structure) FIG. 1 is an external view of an inkjet recording apparatus to which the present invention is applied, and FIG. 2A is a perspective view showing the internal structure of the apparatus.

As shown in FIG. 1, the ink jet recording apparatus 1 of this embodiment has a substrate 2 placed on a tray TR.
It is for performing various kinds of printing on the upper surface 20 of the (printing object), and has a recording apparatus main body 10 and a tray transport table 3 for transporting the tray TR in the direction indicated by arrow A. Depending on the type of the printed material, the printed material may be directly transported by the transport device without using the tray TR or the like.

As shown in FIG. 2A, inside the recording apparatus main body 10 of the inkjet recording apparatus 1, the carriage 11 includes a pulse motor 13 via a timing belt 12.
Is configured to be reciprocated in the width direction (main scanning direction) of the tray TR by being guided by the guide 14.
Further, the tray transport table 3 has a known mechanism in which the rotational driving force from the motor 110 uses a gear, a pulley, a timing belt (all not shown), and the like.
The tray TR can be transported in the direction indicated by the arrow A (sub-scanning direction orthogonal to the main scanning direction). In this way, driven by the motor 110 and the pulse motor 13,
A transport mechanism that relatively moves the carriage 11 or the tray TR is configured.

An ink jet recording head 16 is attached to the surface of the carriage 11 that faces the tray TR, that is, the lower surface in the example shown in this figure. The recording head 16 receives replenishment of ink from an ink cartridge 17 mounted on the upper part of the carriage 11, and in accordance with the movement of the carriage 11, ink is applied to the package upper surface 20 of each substrate 2 arranged on the tray TR. A droplet is discharged to form a dot, and a serial number or the like is printed on the package upper surface 20 of each substrate 2.

A capping device 18 is formed in the non-printing area of the ink jet recording apparatus 1 to seal the nozzle openings of the recording head 16 during the recording pause period, and at the same time during the flushing operation performed during the printing operation. 16
Receives ink drops ejected from. Capping device 1
A cleaning device 19 is disposed in the vicinity of 8, and the cleaning device 19 is configured to wipe the surface of the recording head 16 with a blade or the like to wipe off the ink residue adhering thereto.

Further, in the ink jet recording apparatus 1 of this embodiment, the printed substrate 2 is provided on the back side of the apparatus main body 10, that is, on the side in the direction indicated by the arrow A from the position where the recording head 16 and the like are arranged. Each package top 20
An ultraviolet irradiation device 120 for irradiating ultraviolet rays to solidify and fix the ink attached to the upper surface 20 of the package is arranged. The ultraviolet irradiation device 120 includes an ultraviolet lamp 121, a reflector 122 that reflects the ultraviolet light emitted from the ultraviolet lamp 121 downward, and a protective cover (not shown) that covers these.

The ink used is, for example,
It is prepared by dissolving or dispersing an ultraviolet curable resin, a dye or pigment, a surfactant such as ethylene glycol or the like in a solvent such as water, alcohol, toluene or methyl ethyl ketone. Furthermore, if a heater or the like is attached to the recording head, hot melt ink can also be used.

(Structure of Recording Head 16) FIG.
3 is a cross-sectional view showing the configuration of the recording head 16. FIG.

As shown in FIG. 3A, the recording head 16
A plurality of nozzles 111 are formed in each of the nozzles 111. In each of these nozzles 111, a pressure generating chamber 113 that communicates with the opening of the nozzle 111, and a diaphragm that constitutes one wall surface of this pressure generating chamber 113. A piezoelectric vibrator PZ that deforms 116 to contract the pressure generating chamber 113 and eject ink droplets from the opening of the nozzle 113.
A pressure generating element such as T is configured. Further, a common ink chamber 115 that communicates with the plurality of pressure generating chambers 113 and that sends ink when the pressure generating chambers 113 are expanded is configured.

The vibrating plate 116 is composed of an elastically deformable thin plate, and is a piezoelectric vibrator PZT such as a piezo element.
It is in contact with the tip of the (pressure generating element). In addition, the diaphragm 16 has a thin portion 119 for facilitating its deformation.
Are formed. With such a configuration, the piezoelectric vibrator PZT contracts from the state shown in FIG.
When the pressure generating chamber 113 expands due to the upward deflection, the ink in the common ink chamber 115 flows into the pressure generating chamber 113 via the ink supply port 114. After a lapse of a predetermined time, the piezoelectric vibrator PZT expands, the diaphragm 116 returns to its original position, and the pressure generating chamber 113 contracts. Then, the ink in the pressure generating chamber 113 is compressed, and the nozzles as shown by arrow D are compressed. 111
Ink droplets are ejected from the opening. At this time, a predetermined character or mark is printed depending on which of the many nozzles 111 formed in the recording head 16 ejects the ink droplet.

(Print Head Support Structure) The print head 16 thus configured is supported by the carriage 11 via an actuator 170, unlike a conventional print head, as shown in FIG. 2B. , Can move up and down. Since a high response speed is required for the actuator 170, for example, a CD
A magnetic drive type actuator used in an objective lens driving device of an optical pickup device used for reproducing information from a (compact disc) can be used. The actuator 170 is a magnetic drive type in which the recording head 16 is supported by a plurality of wire springs 172 and the like and is driven by an electromagnet 173.

(Distance Measuring Sensor) As shown in FIG. 3B, in this embodiment, the distance between the recording head 16 and the upper surface 20 (printing surface) of the substrate 2 is measured with respect to the recording head 16. A sensor 160 (distance measuring means) is attached for moving the recording head 16 in the main scanning direction so that the sensor 160 also moves in the main scanning direction together with the recording head 16. Therefore, by using the sensor 16, the distance between the recording head 16 and the upper surface 20 of the substrate 2 in the main scanning direction can be measured. Here, as the sensor 160, a sensor that measures a distance by the intensity of reflected light from a printed material (the upper surface 20 of the substrate 2), a sensor that detects a capacitance with the substrate 2 if the printed material is a metal, a magnetic field It is possible to use one that utilizes the change, one that detects the amount of charge on the printing surface, and the like.

As for the mounting position for the recording head 16, if the distance to the surface to be printed can be measured, for example, as shown in FIG.
It may be located at any position such as a side surface parallel to the main scanning direction 6 or both end surfaces parallel to the sub scanning direction of the recording head 16 as shown in FIG. With the configuration shown in FIG. 3B, the recording head 1 in the main scanning direction can be moved regardless of the bidirectional movement of the recording head 16.
The distance to the printing surface at the same position as 6 can be measured, and
With the configuration shown in (C), even if the recording head 16 is moving in either direction, the two sensors 160
By properly using, the distance to the printing surface can be measured at a position having the same positional relationship with the recording head 16 in the main scanning direction.

(Control System of Inkjet Recording Apparatus) FIG. 4
With reference to, the configurations of the control system and the drive system included in the inkjet recording apparatus according to the present embodiment will be described.

In FIG. 4, the ink jet recording apparatus 1
The control unit 60 configured as described above receives the print command signal and print data from the host, and includes the drive voltage generation circuit 31 and the head selection circuit 32.
In addition to controlling 0, the carriage driving circuit 33 and the tray driving circuit 37 are also controlled to execute the printing operation.
Further, the control means 60 causes the flushing operation to be performed or the recording head 16 based on the time measurement data of the timer means 34.
Perform the cleaning operation of.

In the recording head drive circuit 30, the drive voltage generation circuit 31 is configured to generate a trapezoidal wave having a voltage value required to eject an ink droplet from the opening of the nozzle 111. In addition, the head selection circuit 32 controls the transistor T formed for each nozzle 111 to drive the drive voltage generation circuit 31 to the piezoelectric vibrator PZT corresponding to the print data among the plurality of piezoelectric vibrators PZT. Voltage is selectively applied. The timer means 34 includes a print timer 35, a pause timer 36, and a power-off timer 3.
8 are configured. The print timer 35 is a timer for measuring the duration of the printing operation, and is activated at the start of printing and reset by the flushing operation. Sleep timer 3
6 is backed up by a temporary power source or the like so that the main power source SP can be timed even after the main power source SP is turned off. When the printing operation is stopped and the recording head 16 is sealed by the capping device 18, time counting is started. , It is reset when printing is started. The power-off timer 38 starts timing from the time when the power-on detection means 39 detects that the power switch SW is off, and outputs the relay after the time required to seal the recording head 16 with the capping device 18 elapses. Deactivate 40 to shut off the supply of main power supply SP to the device.

Further, in this embodiment, the output from the distance measuring sensor 160 is input to the control means 60 via the A / D converter 161. In addition, the control unit 60 controls energization to the actuator 170 to adjust the distance from the print surface (the upper surface 20 of the substrate 2) of the recording head 16. That is, the control unit 60 controls the distance measuring sensor 160. The measurement result of the distance to the upper surface 20 of the substrate 2 obtained through the above is temporarily stored in the RAM 601 or the like, and the actuator is arranged to keep the distance to the upper surface 20 of the substrate 2 constant while using the RAM 601 as a working memory. The height position of the recording head 16 is adjusted by controlling 170. Such an operation causes the recording head 16 to move between the upper surface 20 of the substrate 2 and the recording head 16 to be printed while moving in the main scanning direction. Separation distance control means for adjusting the relative distance. This separation distance control means is based on a program stored in a ROM or the like in the recording apparatus main body 10. It can be realized by a CPU that operates Te.

(Printing Operation) As an operation of the ink jet recording apparatus 1 thus constructed, as shown in FIG. 5 (A), the upper surface 20 (printing surface) has a substrate 2 (printing material) having a gentle undulation. The case of printing will be described.

First, in the ink jet recording apparatus 1, in a state where the actuator 170 is returned to the origin and the height position of the sensor 170 is returned to the reference position, ink for one row to be printed is not ejected. The carriage 11 is scanned in the main scanning direction. During such scanning, the sensor 160 measures the relative distance between the recording head 16 and the upper surface 20 of the substrate 2 while the recording head 16 moves in the main scanning direction, and the measurement result indicates the position of the recording head 16. Are stored in the RAM 601 of the control means 60 in association with. Here, the detection range of the sensor 160 has a spatial spread, and the information detected by the sensor 160 configured as shown in FIG. 3B is the width of the recording head 16 in the main scanning direction. It is information obtained from the range corresponding to the dimensions. Therefore, in the present embodiment, among the information obtained in time series from the sensor 160, the value that maximizes the relative distance between the recording head 16 and the upper surface 20 of the substrate 2 is sequentially loaded into the RAM 601 at each time point. It is configured. Therefore, the data taken in the RAM 601 as the relative distance between the recording head 16 and the upper surface 20 of the substrate 2 becomes the information shown in FIG.

Based on such information, the control means 60
As a separation distance control means, as shown in FIG. 5C, the energization to the actuator 170 is controlled, and recording is performed so that the recording head 16 interlocks with the movement of the recording head 16 in the main scanning direction while ejecting ink droplets. The height position of the head 16 is adjusted. As a result, as shown in FIG.
6, the relative distance between the upper surface 20 of the substrate 2 to be printed and the recording head 16 is kept constant while moving in the main scanning direction.

(Main effect of the present embodiment) Therefore, according to the present embodiment, as described with reference to FIG. 7, even when the substrate 2 is warped or undulated, when bidirectional printing is performed,
The ink droplets ejected from the same nozzle opening at the same head position do not shift the landing position on the upper surface 20 of the substrate 2. Therefore, even if the upper surface 20 (printed surface) of the substrate 2 or the like in which the warp or the undulation cannot be avoided, the lines extending in the sub-scanning direction are connected neatly, and printing with high resolution is performed on the surface of the substrate 2 or the like. be able to.

Further, as described with reference to FIG. 8, in the multi-nozzle type recording head 16, openings of a large number of nozzles 111 arranged in six rows are formed at positions separated in the main scanning direction. Even if the positions of the openings are slightly shifted in the sub-scanning direction between the columns, the correction is performed so that the relative distance between the recording head 16 and the upper surface 20 of the substrate 2 becomes constant. On the upper surface 20 (print surface) of the substrate 2 or the like where undulation cannot be avoided, lines extending in the sub-scanning direction are connected neatly. Therefore, substrate 2
It is possible to print with high resolution on the surface of such as.

(Other Embodiments) In the above embodiment, the recording head 16 uses the piezoelectric vibrator PZT or the like to change the volume of the pressure generating chamber 113 communicating with the nozzle 11 to generate ink droplets. Although it was a type that discharges ink, a type that discharges ink droplets by changing the volume of the pressure generating chamber that communicates with the nozzle by vibrating the diaphragm using the electrostatic force generated between the electrodes The present invention can be applied to ones.

In the above-described embodiment, the face eject type in which ink droplets are ejected from the openings of the nozzles 111 provided on the lower surface of the substrate is used. However, the edge eject type in which ink droplets are ejected from the nozzle openings provided at the end of the substrate is used. You can type.

[0035]

As described above, in the ink jet recording apparatus according to the present invention, the distance measuring means measures the relative distance between the recording head and the printing surface while the recording head moves in the main scanning direction, Based on the result, the separation distance control means drives and controls the actuator to adjust the relative distance between the print surface to be printed and the print head while the print head moves in the main scanning direction. Therefore,
Even if the surface to be printed is such that the relative distance to the recording head is likely to change, the relative distance between the surface to be printed and the recording head is always adjusted, so the ink droplet landing position does not shift. . Therefore, high resolution and high quality printing can be performed.

[Brief description of drawings]

FIG. 1 is an external view of an inkjet recording apparatus.

2A and 2B are respectively a perspective view showing a main part inside a main body of the inkjet recording apparatus shown in FIG. 1 and an explanatory view of an actuator provided in a recording head.

3A, 3B, and 3C are perspective views of the recording head used in the inkjet recording apparatus shown in FIG. 1 when viewed from the lower side, and a structure for mounting a distance measuring sensor on the recording head. 3A and 3B are explanatory diagrams showing another mounting structure of the distance measuring sensor with respect to the recording head.

FIG. 4 is a block diagram of a control system and a drive system included in the inkjet recording apparatus shown in FIG.

5 (A), (B), (C), and (D) are respectively,
An explanatory view showing the undulations of the upper surface of the substrate (printing surface) on which printing is to be performed, an explanatory view showing relative distance data between the recording head and the upper surface of the substrate due to the undulations, and driving the actuator based on the relative distance data 6A and 6B are explanatory diagrams showing the relative distance between the recording head and the upper surface of the substrate after driving and correcting the actuator.

6 (A) and 6 (B) are explanatory views showing a state in which ink droplets ejected while the recording head is moving to the right toward the drawing land on the surface of the recording paper.
FIG. 7 is an explanatory diagram showing a state in which the ink droplets ejected while the recording head is moving leftward in the drawing reach the surface of the recording paper.

FIG. 7 is an explanatory diagram showing a deviation of the landing position of ink droplets ejected from a recording head that performs bidirectional printing, and how it is magnified by a change in the relative distance between the recording head and the upper surface of the substrate.

FIG. 8 is an explanatory diagram showing an arrangement of nozzle openings in a multi-nozzle recording head.

[Explanation of symbols]

1 Inkjet recording device 2 substrate (printed material) 3 tray transport table 10 Recording device body 11 carriage 16 recording head 20 Top surface of substrate (printed surface) 60 control means (separation distance control means) 111 nozzles 113 Pressure generation chamber 115 common ink chamber 116 diaphragm 160 sensor (distance measuring means) 170 actuator PZT piezoelectric vibrator TR tray

Claims (3)

[Claims] 1. An inkjet recording apparatus having a head that moves according to a guide, the distance measuring unit measuring a relative distance between the head and the printed surface, and a relative distance between the head and the printed surface. And a separation distance control unit that controls the drive of the actuator based on the measurement result of the distance measurement unit and adjusts the relative distance between the head and the printing surface. An inkjet recording apparatus, wherein the distance between the head and the surface to be printed is adjusted by the separation distance control means when the surface to be printed is scanned. 2. The ink jet recording apparatus according to claim 1, further comprising energy applying means for the surface to be printed. 3. The ink jet recording apparatus according to claim 2, wherein the energy used in the energy applying means is ultraviolet light.