JP2002264315A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid deterioration of print quality when recording is performed using an ink jet recorder. SOLUTION: In the ink jet recorder where recording is performed onto a print medium by carrying the print medium intermittently in the main scanning direction, sliding a print head in the sub-scanning direction and ejecting ink from the nozzle in the print head, carrying amount of the print medium is monitored. If the carrying amount is deficient, data being written at the time of next sliding of the print head in the sub-scanning direction is converted and overlapping of dots is eliminated by ejecting no ink from a nozzle scanning over a printed dot. If the print medium is over carried, carrying direction of the print medium is reversed and the stationary position of the print medium is adjusted while monitoring the carrying amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet recording apparatus, and more particularly, to an ink-jet recording apparatus for correcting the printing medium conveyance accuracy in the main scanning direction and improving the printing quality of the recording result in the main scanning direction on the printing medium. Related to the device.

[0002]

Conventionally, in the ink jet recording apparatus, the print medium intermittently is conveyed to the main scanning direction, while sliding the print head in the sub scanning direction, by ejecting ink from the nozzles in the printhead Recording is performed on a print medium, and FIG. 6 shows an example thereof.

In FIG. 6, a print head 1 can reciprocate along a guide shaft 2 in a sub-scanning direction by driving means. The print medium 3 includes transport rollers 4a,
The print head 1 is supported by the tension rollers 4b and the tension rollers 5a and 5b, and moves in a main scanning direction perpendicular to the sliding direction of the print head 1. A driven gear 6 that meshes with a driving gear 8 described below is fitted to the end of the transport roller 4a. 7
The drive motor for moving the conveying rollers 4a, 8 is a driving gear.

The print head 1 reciprocates in the sub-scanning direction along the guide shaft 2 and prints on the print medium 3 supported by the transport rollers 4a and 4b and the tension rollers 5a and 5b. When the print head 1 is moved to the end portion in the sub-scanning direction of the printing medium 3, the conveying roller 4a is rotated by the drive motor 7, the printing medium 3 is conveyed to the main scanning direction.

[0005] In the conventional ink jet recording apparatus, the conveyance accuracy of the print medium is determined only by the accuracy of the motor control for driving the conveyance mechanism, and the deterioration of the conveyance accuracy of the print medium appears as the deterioration of the print quality.

[0006]

11. SUMMARY OF THE INVENTION The conventional ink jet recording apparatus, the conveyance amount of the print medium is determined only by the control accuracy of the motor for driving the transport mechanism to transmit the power of the driving motor to the conveying mechanism For this reason, there is a problem in that an error occurs in the transport amount due to gear backlash or the like, a predetermined transport accuracy cannot be obtained, and print quality deteriorates.

SUMMARY OF THE INVENTION It is an object of the present invention to avoid deterioration of print quality when recording is performed using an ink jet recording apparatus.

[0008]

Means for Solving the Problems] This object is achieved, the printing medium intermittently conveyed in the main scanning direction, sliding the print head in the sub-scanning direction, printing by ejecting ink from the nozzles of said printhead In an ink jet recording apparatus that performs recording on a medium, the transport amount of the print medium is monitored, and when the print medium transport amount is insufficient, the data drawn when the print head slides in the next sub-scanning direction is converted. Eliminates dot overprinting without ejecting ink from nozzles that scan over already printed print dots,
When the print medium is conveyed excessively, the printing medium conveyance direction is reversed, and this is achieved by adjusting the print medium stationary position while monitoring the conveyance amount.

[0009]

Embodiments of the present invention will be described below.

[0010] In the following embodiments, parts in common with the conventional example of FIG. 6 will not be described are denoted by the same reference numerals.

FIG. 1 is a configuration diagram of a print medium transport mechanism according to an embodiment of the present invention.

[0012] Pulleys 9a,
9b is fitted, the timing belt 10, the conveying rollers 4a, 4b are rotated in conjunction. A rotary encoder fence 1 is provided at the other end of the transport roller 4a.
1 is fitted. Rotary encoder fence 1
Sensor 12 in a manner sandwiching the 1 is disposed, which detects the rotation of the rotary encoder fence 11. Also, 1
Reference numeral 3 denotes a control board that calculates a signal from the detection sensor 12 and controls the drive motor 7.

The print head 1 is reciprocally slid in the sub-scanning direction by driving means along the guide shaft 2, and prints on the print medium 3 supported by the transport rollers 4a and 4b and the tension rollers 5a and 5b. When the print head 1 moves to the end of the print medium 3 in the sub-scanning direction, the drive roller 7 rotates by the drive of the drive motor 7, and the print medium 3 is conveyed in the main scanning direction. The moving distance in the main scanning direction is defined as L1. At this time, the rotary encoder fence 11 also rotates in conjunction with it, and the detection sensor 12
The amount of rotation is monitored. When using a stepper motor to drive the motor 7 to detect the angular velocity of the rotary encoder fence 11 in the print medium conveyance, the overshoot amount in the printing medium resting from the angular velocity, or to predict the undershoot amount, stationary stepping motor Adjust the number of steps remaining until. Drive motor 7 with D
When the C motor is used, the angular velocity of the rotary encoder fence 11 during the conveyance of the print medium is detected, and the amount of overshoot or undershoot when the print medium is at rest is predicted from the angular velocity, and the control current of the DC motor is adjusted. I do.

As another example, when the detection resolution of the detection sensor 12 has an accuracy equal to or smaller than the print dot pitch interval, the conveyance roller 4
Information that the rotation amount of a, that is, the transport amount of the print medium 3 is the distance of N nozzles of the print dot pitch P can be calculated. Further, from the detection signal, deficiency amount of the print medium transport amount, can be detected by the print dot pitch units.

FIG. 2 is a schematic diagram showing the relationship between the nozzle position in the print head and the print dot position. The print medium transport amount L1 and the print width in the main scanning direction drawn by one slide of the print head are shown. when L2 are equal, that is, printing dot groups when the error of conveyance accuracy is zero. The print head 1 is provided with print nozzles 14a, 14b,... For discharging ink to the print medium 3 as shown in the figure. Print dot group 15, the first of the print head 1
Are drawn by the sliding of the print dot group, and the print dot group 16 is a print dot group in a state where the print medium is transported by the distance L1.
It represents a print dot group drawn by the second slide of the print head. The ink is ejected from the nozzles 14a, 14b,... While the print head 1 slides in the sub-scanning direction, and printing on the print medium 3 is performed by repeating the printing of the print width L2 in the main scanning direction. Will be

In FIG. 2, since the error in the accuracy of transporting the print medium is zero, there is no overlap of dots between the print dot groups 15 and the print dot group 16 and no gap between the dots, and no density unevenness or white stripes occur. .

Here, if the moving distance L1 of the printing medium 3 in the main scanning direction is shorter than the printing width L2 in the main scanning direction, that is, if the transport amount of the printing medium is insufficient, the next printing is performed. When ink is ejected from the nozzles 14a, 14b,... While the head 1 slides in the sub-scanning direction, as shown in FIG. There is a portion where the ink lands. Since the overprinted portion has a large amount of ink per unit area, it appears as density unevenness in the entire printing result, and a printing result crushed in the main scanning direction due to the overprinting.

An embodiment of the present invention for preventing the occurrence of the density unevenness and the collapse of the print result will be described.

When the moving distance L1 of the printing medium 3 in the main scanning direction is shorter than the printing width L2 in the main scanning direction, that is, when the conveying amount of the printing medium is insufficient, the rotation of the conveying roller shaft 4a is performed. The print medium transport amount L1 is detected based on sensor information from the detection sensor 12 that detects the amount, and the insufficient transport amount L3 (L3 = L2) with respect to the print width L2 in the main scanning direction.
-L1), and calculates the number N of nozzles required to print the print width L3 in the main scanning direction.

In FIG. 4, when the print medium transport amount is originally accurate, the nozzle a is in row A, the nozzle b is in row B,.
The print data is sent from the print controller to land the ink on the printer.

As shown in FIG. 4, when the print medium transport amount is short by two nozzles, the nozzles a and b scan over the dots that have already been printed, and ink overprinting occurs. I will.

If the print medium transport amount is short by two nozzles, the print controller shifts the print data by two nozzles. That is, nozzle a, nozzle b
Is non-ejection, print data of row A to nozzle c, print data of row B to nozzle d,..., Print data of row J to nozzle l, and row K and row L Control is performed so that printing is performed when the print head slides in the sub-scanning direction.

As described above, by shifting the print data for the number N of nozzles for each nozzle row in the main scanning direction, no ink is ejected from the nozzles that scan the already printed print dots. The hitting is eliminated, and it is possible to prevent density unevenness in the entire print result and collapse of the print result in the main scanning direction.

As another example, the print width L2 in the main scanning direction
When the movement distance L1 of the print medium 3 in the main scanning direction is shorter than that of the print medium 3, that is, when the print medium transport amount is insufficient, the sensor information from the detection sensor 12 that detects the rotation amount of the transport roller shaft 4a is provided. , The print medium transport amount L1 is detected, and the insufficient transport amount L with respect to the print width L2 in the main scanning direction is detected.
Detecting the 3 (L3 = L2-L1), L3 <(NP + 1 /
2P) (where N is the number of nozzles, P is the print dot pitch, and N is an integer), the print data for N nozzles transitions for each nozzle row in the main scanning direction, and when L3 ≧ (NP + ／ P) Changes the print data for N + 1 nozzles for each nozzle row in the main scanning direction. For example, when the underconveyed amount is 1.2 nozzles, the print data for one nozzle is changed, and when the underconveyed amount is 1.7 nozzles, the print data for 2 nozzles is changed. to.

As described above, by adjusting the transition amount of the print data in accordance with the insufficient transport amount, it is possible to minimize the overprint amount of the ink and suppress the density unevenness and the collapse of the print result in the main scanning direction. It becomes possible.

As another example, when the moving distance L1 of the printing medium 3 in the main scanning direction is longer than the printing width L2 in the main scanning direction, that is, when the printing medium is conveyed excessively, When ink is ejected from the nozzles 14a, 14b,... While the print head 1 slides in the sub-scanning direction, as shown in FIG. The ink is landed at a distance (L1-L2). This (L1-L2) appears as a white stripe in the entire print result.

An embodiment of the present invention for preventing the occurrence of white stripes will be described.

When the moving distance L1 of the printing medium 3 in the main scanning direction is longer than the printing width L2 in the main scanning direction, that is, when the printing medium is conveyed excessively, the drive motor 7 is rotated in the reverse direction. Then, the transport roller 4a and the transport roller 4b are also reversely rotated in conjunction with each other, the transport direction of the print medium 3 in the main scanning direction is reversed, and the rotation amount of the transport roller shaft 4a is monitored by the detection sensor 12.

In this embodiment, an example of an ink jet recording apparatus for ejecting liquid ink droplets at normal temperature is described. However, by using a heater provided in the print head 1, a range from 80 degrees Celsius to 140 degrees Celsius is used. In the ink path including the ink chamber warmed at the temperature, the hot melt type ink that is solid at room temperature is changed into a liquid by heating, and in a hot melt inkjet recording apparatus that ejects ink droplets, by the same means as described above, detecting a conveyance amount L1 in the main scanning direction of the print medium 3 by the detection sensor 12, the printing medium 3
Rest position to adjust, it is possible to prevent the collapse and white stripe density unevenness and printing result of the printing results.

[0030]

By using the ink jet recording apparatus of the present invention, the transport distance of the print medium is monitored, the stationary position of the print medium is controlled, and the print data is converted by the stationary position, whereby the main scanning of the print medium is performed. it is possible to enhance the direction of the ink landing position accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a print medium transport mechanism according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a dot landing position (when a printing medium conveyance accuracy error is zero).

FIG. 3 is a diagram illustrating an example of a conventional dot landing position.

4 is a diagram illustrating an example of the dot landing position in the present embodiment.

FIG. 5 is a diagram illustrating an example of a conventional dot landing position different from FIG.

FIG. 6 is a configuration diagram showing a specific example of a conventional print medium transport mechanism.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Print head, 3 ... Printing medium, 4a, 4b ... Conveyance roller, 7 ... Drive motor, 11 ... Rotary encoder fence, 12 ... Detection sensor, 13 ... Control board, 14
a, 14b: print nozzles.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Eiichi Toyama 1060 Takeda, Hitachinaka-shi, Ibaraki F-term in Hitachi Koki Co., Ltd. (reference) 2C056 EA06 EA08 EB03 EB12 EB37 EC07 EC12 EC34 EC77 FA04 FA10 FD02 HA29 2C057 AF30 AF31 AG12 AH15 AL03 AL21 AM03 AM25 AM30 AM40 AN01 BA03 BA14 DA09 DB01 DB03 DC02 DD09 DE02 DE10 2C058 AB17 AC07 AE02 AE09 AF20 AF23 GA03 GB07 GB20 GB43 GB47 GE17 2C059 AA22 AA26 AA38 AA64

Claims (6)

[Claims] 1. An ink jet recording method in which a print medium is intermittently conveyed in a main scanning direction, a print head is slid in a sub scanning direction, and ink is ejected from nozzles of the print head to perform recording on the print medium. In the apparatus, the transport amount of the print medium is monitored, and when the transport amount of the print medium is insufficient, the data drawn when the print head slides in the next sub-scanning direction is converted, and the data printed on the already printed print dots are converted. Eliminate overprinting of dots without ejecting ink from the scanning nozzles.If the print medium is transported excessively, reverse the print medium transport direction and adjust the print media stationary position while monitoring the transport amount. An ink jet recording apparatus characterized by the above-mentioned. 2. An ink jet recording method in which a print medium is intermittently conveyed in a main scanning direction, a print head is slid in a sub scanning direction, and ink is ejected from nozzles of the print head to perform recording on the print medium. In the apparatus, a function of providing a rotary encoder on a transport roller shaft constituting a part of a print medium transport mechanism, detecting a rotation amount of the transport roller shaft with a sensor, and adjusting a stationary position of the print medium based on information of the sensor. And a detection resolution of a sensor for detecting a rotation amount of the transport roller shaft is set to be equal to or less than a print dot pitch interval. 3. The ink jet recording apparatus according to claim 2, wherein a print medium conveyance amount is detected based on sensor information from a sensor for detecting a rotation amount of a conveyance roller shaft, and printing in one sub-scanning direction is performed. The print medium transport amount detected by the sensor is smaller than the print width of the print medium in the main scanning direction drawn by the sliding of the head, and when the print medium transport amount is insufficient, it corresponds to the transport distance shortage amount. Calculate the number of nozzles required to print the print width in the main scanning direction, and when the print head slides in the next sub-scanning direction, transition the print data for the number of nozzles for each nozzle row in the main scanning direction. An ink jet recording apparatus characterized in that ink is not ejected from a nozzle that scans a printed dot that has already been printed. 4. The ink jet recording apparatus according to claim 2 or 3, detects the print medium conveyance amount based on the sensor information from a sensor for detecting the rotation amount of the conveying roller shaft, to one sub-scan direction When the print medium transport amount detected by the sensor is smaller than the print width in the main scanning direction of the print medium drawn by the slide of the print head, and the print medium transport amount is insufficient, the transport distance shortage L Is L <
(NP + 1 / 2P) (N is the number of nozzles, P is printed dot pitch, N is an integer) shifts the print data of the N nozzles in each nozzle row in the main scanning direction in the case of, also L ≧ (NP + 1 /
In the case of 2P), an ink jet recording apparatus is characterized in that print data for N + 1 nozzles transitions for each nozzle row in the main scanning direction, and ink is not ejected from nozzles that scan over already printed print dots. 5. The ink jet recording apparatus according to claim 2, wherein a print medium conveyance amount is detected based on information from a sensor for detecting a rotation amount of a conveyance roller shaft, and the one time operation is performed. Than the printing width in the main scanning direction of the print medium drawn by sliding the print head in the sub-scanning direction,
If the print medium transport amount detected by the sensor is longer, and the print medium is transported excessively, the transport roller is rotated in the reverse direction to reverse the transport direction of the print medium in the main scanning direction, and the transport distance excess amount is reduced. returning, ink jet recording apparatus characterized by adjusting the rest position of the print medium. 6. The ink jet recording apparatus according to claim 2, wherein the temperature is from 80 degrees Celsius to 1 degree Celsius.
The ink chamber volume warmed at a temperature in the range of 40 degrees, by varying with a piezoelectric element, hot-melt ink jet recording apparatus characterized by ejecting ink from the nozzles.