JP2004009430A - Ink jet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To overcome the difficulty in adjusting the horizontal registration by the ink color without the need of using a paper or an ink when adjusting the registration. <P>SOLUTION: A sensor for adjusting the registration is provided on the platen 202 side to directly scan a nozzle part of a head, so that the displacement amount is measured for each head and it is corrected based on the displacement amount. The distance between nozzles of a plurality of recording heads is calculated based on a detected signal to lag the recording timings of the recording heads according to the calculated value. A projection showing the nozzle part position is provided in the heads, and thereby the recording nozzle positions can be detected easily. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink jet recording apparatus that performs recording by discharging ink onto a recording medium, and particularly to a case where color recording is performed by arranging a plurality of recording heads in a main scanning direction, the positional deviation between the recording heads. Regarding correction.
[0002]
[Prior art]
An ink jet recording apparatus is composed of an ink tank and a recording head for discharging ink droplets. The basic operation of the recording head will be described with reference to FIG.
[0003]
FIG. 3 is a diagram schematically showing a longitudinal sectional view of a part of the ink ejection portion of the print head 9 (the same applies to any of the print heads 9A to 9D).
[0004]
In FIG. 3, a plurality of ink ejection ports 10 are formed at a predetermined pitch in the vertical direction on a surface facing the recording medium 1. 10A is a liquid path, and 13 is ink. When an electro-ripening converter (heating resistor or the like) 11 provided corresponding to each ink ejection port 10 is energized and heated based on the recording information, a film boiling phenomenon occurs in the ink and a bubble (bubble) 12 is generated. The ink is ejected by this pressure, and a flying ink droplet 13A is formed. By applying the ink droplets on the recording medium 1 in a predetermined pattern, recording by a dot pattern is performed. After that, when the energization heating in step 11 is stopped, the inside of the recording head nozzle is cooled, and the bubble (bubble) 12 disappears.
[0005]
Each recording head 9 is provided with a heat driver 14 for turning on / off the energization of the electrothermal converter, which outputs an output signal from a print data serial / parallel conversion circuit 16 and a heat signal generation circuit 17. Driven to the original.
[0006]
The electrical configuration of the ink jet recording apparatus will be described with reference to FIG.
[0007]
In FIG. 4, a CPU 21 performs various controls based on a control program stored in a program memory 24 in a ROM form. The working memory 25 in the form of a RAM is used for temporarily storing, processing, and processing various control signals and print data received from the host apparatus 100 via the ink face 22 by the CPU 21. The CPU 21 operates by controlling each motor control circuit 42 or 44 via an output port 26 on a drive source such as a motor of each company based on the above-described print data, and also through a print head control circuit 29 on the carriage 6. A drive signal for the electro-ripening converter is sent to each of the recording heads 9A to 9D.
[0008]
Thereby, an image is formed on the recording medium.
[0009]
In addition, the power supply circuit 28 supplies a logic drive voltage Vcc (for example, 5 V) for operating the control logic circuit, a motor drive voltage VM (for example, 30 V) for each motor, and an electric power to the electrothermal converter 11 of the recording head 9 to generate heat. Of the heat voltage VH (for example, 25 V).
[0010]
FIG. 2 shows a configuration example of a conventional ink jet type color ink jet recording apparatus.
[0011]
2, a recording medium 1 such as a sheet of paper or a plastic sheet is conveyed in a direction indicated by an arrow A by a pair of conveyance rollers 2 and 3 arranged above and below a recording area and by a conveyance roller 2 driven by a sheet feed motor 70. Is done. A guide shaft 5 is provided in front of the transport rollers 2 and 3 in parallel with the transport rollers. The carriage unit 6 is reciprocated in the direction of arrow B via the belt 8 by the output of the carriage motor 72 along the guide shaft.
[0012]
The carriage unit 6 serving as a head moving unit is equipped with a BJ type ink jet recording head 9. The recording head 9 is for a color image, is arranged in the operation direction of the carriage, and is provided corresponding to each color ink of cyan (c), magenta (M), yellow (Y), and black (Bk). And four recording heads 9, that is, a black head 9A, a cyan head 9B, a magenta head 9C, and a yellow head 9D. Each recording head can be arranged at a certain interval (for example, 12 mm). The front surface of each recording head 9, that is, the surface opposing the recording surface of the recording medium 1 at a predetermined interval (for example, 5 mm), has a plurality of (for example, 64) ink ejection ports as a direction intersecting the operation direction of the carriage. Ink ejection units arranged in a line are provided.
[0013]
An operation panel 160 attached to an outer case (not shown) of the recording apparatus includes key setting units such as an online / offline switching key 60A, a line feed key 60B, a form feed key 60C, and a recording mode switching key 60D. The display unit includes an LED such as an alarm LED 61A and an online / offline display LED 61B, and a display unit including a display LCD 65 for making the state of the recording apparatus external.
[0014]
The portion hidden by the carriage unit 6 in FIG. 2 includes a capping mechanism 45 for protecting the print head when printing is not performed, an absorber for wiping the nozzle surface of the print head, and a pointing member therefor. A wiping mechanism 46 and a recovery motor 72 for operating these are provided.
[0015]
When performing a recording operation, the CPU 21 (FIG. 1) on a control board (not shown) and its peripheral circuits first use the sheet feed motor 70 to move the recording medium 1 to a predetermined position. The CPU 21 processes the data received from the host 100, scans the carriage unit 6 based on the processed data, controls the recording head 9, and executes appropriate recording on the recording medium 1. When recording for one scan is completed, the recording medium 1 is again moved in the direction orthogonal to the scanning direction by using the sheet feed motor 70, and the carriage is again scanned for recording. This is repeated to record on the entire recording medium.
[0016]
[Problems to be solved by the invention]
In recent years, it has become important to correct lateral displacement of heads of respective colors arranged in the horizontal direction due to an increase in recording density and an increase in the quality of recorded images.
[0017]
As means for correcting the displacement, there is a means for providing a displacement detection sensor on the carriage, detecting the position by this, and correcting the displacement.
[0018]
The following is an example of an actual correction procedure.
[0019]
First, a specific recording image for detecting a displacement amount is received from the host side, this is recorded on a recording medium, and the displacement amount is detected by a displacement detection sensor provided on a carriage.
[0020]
Next, based on this information, when recording is actually performed, the recording pulse input timing is changed for each head to correct the positional deviation.
[0021]
In the above-mentioned conventional procedure, it may be difficult for the sensor to detect the ink depending on the color density (OD value) of the ink ejected from the recording head.
[0022]
Further, a recording medium and ink have to be separately used for correcting the positional deviation, which has led to an increase in utilization cost (running cost) for a user of the recording apparatus.
[0023]
[Means for Solving the Problems]
In order to address such a problem, the present invention arranges a sensor for detecting the amount of displacement on the platen side of the main body and directly scans the nozzle side of the head, so that the position can be determined regardless of the color of ink even in an inexpensive configuration. It is an object of the present invention to provide a position shift correcting unit which enables detection of a shift amount and does not use a recording medium or ink.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
Hereinafter, the present invention will be described with reference to FIGS.
[0025]
FIG. 1 is a schematic diagram schematically illustrating the present invention.
[0026]
In FIG. 1, the carriage 6 moves from left to right, and at that time, the surface of the recording head is scanned by an optical sensor 201 attached to the main body.
[0027]
FIG. 5 shows an example of a circuit of an optical sensor, an output signal of the sensor, and a method of specifying the position of the nozzle based on this signal. According to the present invention, a high-brightness coating is performed on the portions other than the nozzles on the nozzle surface of the head so that the peripheral portion other than the nozzles has high reflection and the nozzle portion has low reflection.
[0028]
Therefore, as the output signal of the sensor, the voltage of the peripheral portion is high, and the voltage of the nozzle portion is extremely small.
[0029]
This signal is input to the input port 32 of the CPU 21 and is converted into a logic signal (high / low).
[0030]
FIG. 6 shows a flowchart of the correction procedure.
[0031]
First, the carriage 6 is moved as described above.
[0032]
At this time, the surface of the recording head is scanned to detect signal change points x1, x2, x3, x4, x5, x6, x7, and x8 shown in FIG.
[0033]
Next, the CPU 21 calculates the center of each nozzle (XBk, XC, XM, XY) from the read change point information. The calculation formula is as follows.
[0034]
XBk = (x1 + x2) / 2
XC = (x3 + x4) / 2
XM = (x5 + x6) / 2
XY = (x7 + x8) / 2
Next, the CPU 21 calculates the deviation amounts (ΔC, ΔM, ΔY) between the Bk head and the other heads. The calculation formula is as follows.
[0035]
ΔC = XC−XBk
ΔM = XM−XBk
ΔY = XY−XBk
The correction is performed by comparing ΔC, ΔM, and ΔY with a reference value stored in the ROM in advance when the deviation amount is zero.
[0036]
As a correction method, when actually performing the printing operation, the timing of the ejection pulse output to each head is shifted. When the difference between the nozzles is smaller than the reference value, the timing is delayed, and the difference between the nozzles is larger than the reference value. If so, make the timing earlier. By changing the timing in this way, as a result of the recorded image on the recording medium, a good image without deviation is formed.
[0037]
(Embodiment 2)
In the first embodiment, high-brightness coating is performed on the periphery of the nozzle portion to facilitate detection, but a protrusion may be provided on an extension of the nozzle portion of the head to detect this. Good.
[0038]
【The invention's effect】
As described above, the present invention is implemented, a sensor for detecting the amount of displacement is arranged on the platen side of the main body, and the nozzle side of the head is directly scanned. It is possible to perform the amount detection, and to perform the positional deviation correction without using the recording medium or the ink.
[Brief description of the drawings]
FIG. 1 is a simple configuration diagram for explaining the present invention.
FIG. 2 is a schematic perspective view showing a main part of a conventional color ink jet printer.
FIG. 3 is a diagram schematically illustrating a cross section of a head.
FIG. 4 is a block diagram illustrating an electrical configuration of a color inkjet printer according to the present invention.
FIG. 5 is a diagram showing a circuit configuration of a sensor and an output signal according to the present invention.
FIG. 6 is a flowchart showing a correction procedure in the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 recording medium 2 transport roller 3 transport roller 5 guide shaft 6 carriage unit 8 belt 9 recording head 9A black recording head 9B cyan recording head 9C magenta recording head 9D yellow recording head 10 ink discharge nozzle 10A ink liquid path 11 Electrothermal converter 12 Bubble
13 Ink 13A Flying ink droplet 14 Heat driver 16 Print data serial / parallel conversion circuit 17 Heat signal generation circuit 21 CPU
23 Data memory 24 Program memory 25 Working memory 28 Power supply device 29 Recording head control circuit 30 A / D conversion circuit 41 Recovery mechanism motor control circuit 42 Carriage motor control circuit 43 Transport mechanism 44 Sheet feed motor control circuit 45 Capping mechanism 46 Wiping mechanism 60A-60D Operation key 60E Alarm LED
60F LED for online / offline display
70 sheet feed motor 71 carriage motor 72 recovery motor 100 host device 160 operation panel 201 optical sensor 202 platen

Claims (4)

The recording head has a plurality of recording elements arranged in a direction perpendicular to the scanning direction of the recording head, and scans at least two or more of the recording heads to use the recording elements on a recording medium. In a recording device in which recording is performed,
Nozzle means for the plurality of recording heads, and means for detecting a difference between other parts,
Based on the detected signal, the distance between the nozzles of a plurality of recording heads is obtained,
An ink jet recording apparatus characterized in that the recording timing of each recording head is shifted by this value. An ink jet printing apparatus, wherein the means for identifying the nozzle portion of the print head and other portions is an optical sensor provided on the printing apparatus side. A recording head, comprising: means for increasing the contrast between the nozzle portion and other portions of the recording head, thereby facilitating the detection of the position of the recording nozzle. A print head, wherein a protrusion indicating a position of a nozzle portion is provided on the print head, thereby facilitating detection of a position of a print nozzle.

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