JP2004114540A - Color printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simply adjust misregistration with high accuracy in a short period of time. <P>SOLUTION: CCD line sensors 15 and 21 for detecting a printing position of a yellow image and that of a magenta image each are arranged downstream in the paper feeding directions of a thermal head 12 for yellow and a thermal head 18 for magenta. In the printing of the magenta image, the printing position is adjusted according to the printing position of the yellow image, which is detected by the line sensor 15 for the yellow, and the misregistration between the yellow image and the magenta image is prevented. In the printing of a cyan image, a printing position is adjusted according to the printing position of the magenta image, and the misregistration among the yellow image, the magenta image and the cyan image is prevented. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color printer, and more particularly to prevention of misregistration of a color printer that records a full color image with a plurality of print heads.
[0002]
[Prior art]
As a type of color printer, there is a color thermal printer that records an image by pressing the heating element of the thermal head against the recording surface of the color thermal recording paper and coloring the yellow, magenta, and cyan thermal coloring layers of the color thermal recording paper is there. In addition, in this color thermal printer, a color thermal recording paper is passed through one thermal head three times to perform thermal recording, and a recording paper is passed once through a plurality of thermal heads. There is a one-pass method for performing thermal recording. Since this one-pass method has a shorter printing time than the three-pass method, it is used for a commercial color thermal printer that prints a large number of sheets continuously.
[0003]
In a one-pass color thermal printer, if printing is performed in a state where the printing positions of the respective colors do not match, a color registration shift (hereinafter abbreviated as registration shift) occurs. This misregistration occurs in two directions, the main scanning direction and the sub-scanning direction, and deteriorates the print quality.
[0004]
Therefore, in the conventional color thermal printer, the registration position is corrected for each color and the print position is adjusted. The correction of the registration error has been obtained by calculation in consideration of a conveyance system error of the recording paper, errors due to various temperature dependencies (environment temperature where the printer is installed, temperature in the printer), experience values, and the like. Errors unique to each device have been adjusted in the inspection process at the time of printer manufacture. Further, there is known a thermal transfer printer that adjusts registration misalignment by setting each color print start position and adjusting / changing setting of ink sheet tension by operating a variable device (for example, Patent Document 1). reference).
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 9-234917
[Problems to be solved by the invention]
The conventional registration misalignment correction method requires various measuring devices and the like, and the calculation is complicated, so that it cannot be easily performed. In particular, since it takes a long time for a serviceman to adjust the registration error at a customer or the like, it has been desired that the adjustment of the registration error be completed in a short time. Further, in the registration deviation adjusting method described in Patent Document 1, it takes time because appropriate registration deviation adjustment is not performed unless adjustment and test printing are repeated several times. Furthermore, since the registration deviation adjustment is performed by the user's sense, it is not stable and the original performance of the printer may not be exhibited.
[0007]
In addition, for users who use color printers for business, frequent registration misalignment and registration misalignment adjustment interfere with business, so it has been desired that registration misalignment can be adjusted during printing.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to provide a color printer that can easily perform registration misalignment adjustment in a short time and can be adjusted during printing. .
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems, the color printer of the present invention arranges line sensors for detecting the print position of an image printed by the upstream print head in the vicinity of each print head, and these line sensors. In accordance with the print position detected by the above, an adjusting means for adjusting the print position by the downstream print head is provided.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic diagram showing the configuration of a color thermal printer embodying the present invention. In this printer, a recording paper roll 3 obtained by winding a long color thermal recording paper 2 in a roll shape is used as a recording medium. The recording paper roll 3 is set in the paper feeding unit of the color thermal printer, and the paper feeding roller 4 is pressed against the outer periphery. The paper feed roller 4 rotates the recording paper roll 3 to pull out the color thermosensitive recording paper 2 and feeds it into the transport path from the paper feed unit to the paper discharge port. After the printing is completed, the color thermal recording paper 2 is rewound onto the recording paper roll 3 to prevent the influence of light and humidity.
[0011]
As is well known, the color thermosensitive recording paper 2 has a cyan thermosensitive coloring layer, a magenta thermosensitive coloring layer, and a yellow thermosensitive coloring layer sequentially provided on a support. The yellow thermosensitive coloring layer, which is the uppermost layer, has the highest thermal sensitivity and develops yellow with a small amount of heat energy. The cyan thermosensitive coloring layer, which is the lowermost layer, has the lowest thermal sensitivity and develops cyan with large heat energy. The yellow thermosensitive coloring layer loses its coloring ability when irradiated with near ultraviolet rays of 420 nm. The magenta thermosensitive coloring layer develops magenta with intermediate thermal energy between the yellow thermosensitive coloring layer and the cyan thermosensitive coloring layer and loses the coloring ability when irradiated with 365 nm ultraviolet rays. For example, a black thermosensitive coloring layer may be provided on the color thermosensitive recording paper 2 to form a four-layer structure.
[0012]
A yellow printing unit 6 that prints a yellow image from the upstream side in the paper feeding direction, a magenta printing unit 7 that prints a magenta image, and a cyan printing unit 8 that prints a cyan image are arranged in the conveyance path. Each printing unit is controlled by a controller 9 comprising a ROM storing a CPU and a control program, an EEPROM storing various data for control, a RAM temporarily storing various data obtained during operation, various driver circuits, and the like. Has been.
[0013]
The yellow printing unit 6 includes a yellow transport roller pair 11, a yellow thermal head 12, a yellow platen roller 13, a yellow fixing lamp 14, and a yellow CCD line sensor 15.
[0014]
The yellow transport roller pair 11 rotates while sandwiching the color thermal recording paper 2 and transports the color thermal recording paper 2 in the paper feeding direction. The yellow thermal head 12 generates heat by being pressed against the color thermal recording paper 2 being conveyed in the paper feeding direction, and thermally records a yellow image on the yellow thermal coloring layer. The yellow platen roller 13 supports the color thermal recording paper 2 from below and stabilizes the contact state with the yellow thermal head 12. The yellow fixing lamp 14 emits near-ultraviolet light having an emission peak of 420 nm and fixes the yellow thermosensitive coloring layer 2 of the color thermosensitive recording paper 2 so as not to develop color even when heated.
[0015]
As shown in FIG. 2, the yellow CCD line sensor 15 is formed longer than the width dimension (length in the main scanning direction) of the color thermal recording paper 2, and a plurality of pixels 16a are arranged in the main scanning direction. The detection unit 16 is provided. The yellow CCD line sensor 15 detects the print position (position in the main scanning direction and position in the sub-scanning direction) of the yellow image printed by the yellow thermal head 12 and inputs it to the controller 9.
[0016]
The magenta printing unit 8 has substantially the same configuration as the yellow printing unit 7, and includes a magenta transport roller pair 17, a magenta thermal head 18, a magenta platen roller 19, a magenta fixing lamp 20, and a magenta CCD line. Sensor 21. The magenta fixing lamp 20 emits ultraviolet rays having an emission peak of 365 nm to fix the magenta thermosensitive coloring layer.
[0017]
The cyan printing unit 9 includes a cyan conveyance roller pair 23, a cyan thermal head 24, and a cyan platen roller 25. Since the cyan thermosensitive coloring layer has a thermal sensitivity that does not cause color development under normal storage conditions, it does not have photofixability. Moreover, since it is the last printing part, a CCD line sensor is also unnecessary.
[0018]
A paper discharge port 28 through which the printed color thermal recording paper 2 is discharged is provided at the most downstream side in the paper feeding direction of the transport path. A cutter 29 that cuts the long color thermal recording paper 2 into a sheet shape at a predetermined position is disposed behind the paper discharge port 28.
[0019]
Next, the registration deviation adjustment of the above embodiment will be described with reference to the flowchart of FIG. The color thermal printer has a registration shift adjustment mode. When the color thermal printer is set to the registration error adjustment mode, the controller 9 rotates the paper feed roller 4 to send out the color thermal recording paper 2 from the recording paper roll 3.
[0020]
The color thermal recording paper 2 is fed into the conveyance path and is sandwiched between the yellow conveyance roller pair 11 of the yellow printing unit 7. The yellow transport roller pair 11 transports the color thermal recording paper 2 in the paper feeding direction at a transport speed for printing. When the color thermal recording paper 2 reaches a preset printing start position, the yellow thermal head 12 prints a yellow cross pattern 32 shown in FIG. 2 on the color thermal recording paper 2.
[0021]
The yellow CCD line sensor 15 scans the recording surface of the color thermal recording paper 2 by the detection unit 16 and detects a cross pattern 32. This detection signal is input to the controller 9. The yellow fixing lamp 14 fixes the yellow thermosensitive coloring layer by irradiating the color thermosensitive recording paper 2 with near ultraviolet rays having an emission peak of 420 nm.
[0022]
The controller 9 calculates, from the detection signal input from the yellow CCD line sensor 15, the print start position from the front end of the recording paper and the position of the heating element to be driven as the print position for printing the next magenta image. To do. Then, the print position data of the magenta image stored in advance in the EEPROM of the controller 9 is rewritten.
[0023]
When fixing of the yellow thermosensitive coloring layer is completed, the yellow fixing lamp 14 is turned off. The leading edge of the color thermal recording paper 2 reaches the magenta printing unit 8 and is sandwiched by the magenta transport roller pair 17. The magenta transport roller pair 17 transports the color thermal recording paper 2 in the paper feeding direction at the transport speed for printing. When the leading end of the recording area of the color thermal recording paper 2 reaches the printing start position calculated by the controller 9, the magenta thermal head 18 starts to print a magenta cross pattern by causing a predetermined heating element to generate heat.
[0024]
The magenta cross pattern is printed based on the main scanning direction position and the sub-scanning direction position of the yellow cross pattern 32 detected by the yellow CCD line sensor 15. For this reason, the yellow cross pattern and the magenta cross pattern are neatly overlapped, and no registration error occurs.
[0025]
The magenta CCD line sensor 21 detects a magenta cross pattern and inputs the detection signal to the controller 9. Further, the magenta fixing lamp 20 is turned on to fix the magenta thermosensitive coloring layer. The controller 9 calculates a printing position when printing the next cyan image from the detection signal input from the magenta CCD line sensor 21. Then, the printing position data of the cyan image stored in advance in the EEPROM of the controller 9 is rewritten.
[0026]
When the fixing of the magenta thermosensitive coloring layer is completed, the magenta fixing lamp 20 is turned off. The color thermal recording paper 2 is nipped by the cyan conveyance roller pair 23 and conveyed in the paper feeding direction. When the leading end of the recording area of the color thermal recording paper 2 reaches the cyan image printing start position calculated by the controller 9, the cyan thermal head 24 generates a predetermined heating element based on the cyan image printing position. The cyan cross pattern is printed on the color thermal recording paper 2.
[0027]
Since the cyan cross pattern is printed based on the main scanning direction position and the sub-scanning direction position of the yellow cross pattern and the magenta cross pattern detected by the magenta CCD line sensor 21, no registration deviation occurs.
[0028]
The recording area on which the cyan cross pattern of the color thermal recording paper 2 is printed is cut by the cutter 29 and discharged from the paper discharge port 28. The controller 9 rewinds the color thermosensitive recording paper 2 onto the recording paper roll 3 using the paper feed roller 4 and each of the transport roller pairs 11, 17, and 23, and the registration deviation adjustment mode ends.
[0029]
This registration misalignment adjustment mode can be implemented without using special measurement equipment and adjustment equipment, and because the adjustment time is short, there is no problem in user operations due to the registration misalignment adjustment at the customer site. . In addition, since the print start position is adjusted by actually detecting the print position of each color, it is possible to perform registration displacement adjustment with high accuracy. Furthermore, the inherent error for each device can be sufficiently adjusted in the registration error adjustment mode, so that the registration error adjustment in the inspection process at the time of printer manufacture can be omitted.
[0030]
In the above embodiment, the CCD line sensor is incorporated in the yellow printing unit 6 and the magenta printing unit 7, but a CCD line sensor may be incorporated in the cyan printing unit 8. The CCD line sensor of the cyan printing unit 8 can detect a cross pattern that has been overprinted and use it to determine the result of registration deviation adjustment.
[0031]
In the above embodiment, the registration error adjustment is performed when the registration error adjustment mode is performed. However, the registration deviation adjustment may be performed not only in the registration deviation adjustment mode but also in a normal printing operation. In this case, as shown in FIG. 4, the print position of the yellow image 35 printed on the color thermal recording paper 2 may be detected by the yellow CCD line sensor 15 and input to the controller 9.
[0032]
In the above embodiment, a color thermal printer has been described as an example. It can be used for a printer for printing.
[0033]
【The invention's effect】
As described above, according to the color printer of the present invention, it is possible to easily perform high-precision registration deviation adjustment in a short time without using a special device. In addition, since the registration deviation can be adjusted during the printing operation, it is possible to always perform the optimum registration printing.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the configuration of a color thermal printer embodying the present invention.
FIG. 2 is a plan view showing a color thermal recording paper and a yellow CCD line sensor in a registration error adjustment mode.
FIG. 3 is a flowchart illustrating a procedure of a registration error adjustment mode.
FIG. 4 is a plan view showing a color thermal recording paper and a yellow CCD line sensor during normal printing.
[Explanation of symbols]
2 Color thermal recording paper 6 Yellow printing section 7 Magenta printing section 8 Cyan printing section 9 Controllers 15 and 21 CCD line sensor 32 Cross pattern

Claims (1)

In a color printer in which a plurality of print heads for printing different colors are arranged along a recording paper conveyance path, and a full color image is recorded by performing printing with each print head while the recording paper moves in the conveyance path. ,
A line sensor for detecting the print position of an image printed by the upstream print head is arranged in the vicinity of each print head, and the downstream print head is arranged according to the print position detected by these line sensors. A color printer comprising adjusting means for adjusting the printing position by means of the above.

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