JPS63272560A - Printer - Google Patents

Abstract

PURPOSE:To obtaing a printer which causes no shifted printing, by detecting shifted amount of first color print with respect to a print head then shifting print data correspondingly based on an output from a position detecting means. CONSTITUTION:A line of data is fed to heating elements in a print head 1 and printed, then a paper 6 is moved in the direction of an arrow A by means of a platen roller 5. When printing in magenta finishes and the print head 1 comes to the end of paper, a sensor detects the end of paper and outputs a reverse feed signal. Upon receipt of the reverse feed signal, the platen roller 5 rotates reversely so as to feed the paper 6 in the direction of an arrow 8. Then a sheet 1 is moved to the position of cyan 1c. Printing in cyan is carried out similarly with printing in magenta. Here, the space between lines printed with magenta is detected through a print position detecting means 9 and feeding amount of paper is adjusted in order to prevent color shift in carrying direction. Consequently, color shift in carrying direction of paper 6 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printer that performs multicolor recording, and particularly to an improvement in recording deviation thereof.

[Conventional Technique t#] FIG. 4 shows the configuration of a conventional printer disclosed in Japanese Patent Application Laid-Open No. 61-31290. A print head 4 is provided with heating elements arranged in a negative row. An ink sheet 1 and paper 6 are inserted between the print head 4 and the platen roller 5. The ink sheet 1 has three colors: yellow la, magenta 1b, and cyan 1c, and in the figure, magenta is printed. A portion of the data is sent to the heating element of the print head 1, and when printing for - lines is completed, the paper 6 is moved in the direction of arrow A by the platen roller 5.

When the magenta printing is finished, the paper 6 is moved to the platen roller.
5 causes it to be fed backward in the direction of arrow B.

Next, in order to print in cyan, sheet 1 is printed in cyan 1.
Move it to position c. Cyan is printed in the same way as magenta. However, to avoid color shift,
Lightly change the line spacing of magenta print that has already been printed! 7 and light receiving element 8 to adjust the amount of paper feed.

That is, paper feeding is started when the printing of the - line is completed, and paper feeding is stopped when the next printing line is detected by the light receiving element 8. This prevents color shift in the conveyance direction of the paper 6.

[Problems to be Solved by the Invention] The conventional printer as described above can prevent misalignment of printing in the paper conveyance direction. However, there is a problem in that it is not possible to prevent misalignment of printing in the direction perpendicular to the paper conveyance direction.

It is an object of the present invention to solve the above-mentioned problems and provide a printer that does not cause misalignment of printing.

[Means for Solving the Problems] The printer according to the present invention has a printing position that detects how far the printing position in the direction perpendicular to the conveying direction of the first color deviates from the normal position with respect to the print head. Data shifting means is provided for shifting data given to each printing means to the right or left based on the outputs of the detection means and the print position detection means.

[Operation] The position detecting means detects how far the first color print is deviated from the print head. The data shift means shifts the print data by the amount of shift based on the output of the position detection means.

[Embodiment 1] FIG. 1 shows the structure of a printer according to an embodiment of the present invention.Heating elements, which are printing means, are arranged on a print head 4 at predetermined intervals. A platen roller 5 is provided at a position facing the print head 4, and an ink sheet 1 and a recording paper 6 are inserted between them. The ink sheet 1 is composed of three color parts: yellow 1a, magenta lb, and cyan IC. Currently, magenta is being printed. A position detecting means 9 is provided on one end of the platen roller 5, facing the printing surface of the paper 6.

A plan view of the position detection means 9 is shown in FIG. 2A, and a side sectional view is shown in FIG.
The light emitting diodes of the 0 light emitting diode array 11 shown in FIG. The side is composed of a condensing lens array 12 and a CCD 10. Since the amount of light reflected from the light emitting diode changes depending on the presence or absence of the printed dot, the position of the printed dot is detected based on this.

When a portion of the data is sent to the heating element of the print head 10 and printing of the portion is completed, the paper 6 is moved in the direction of arrow A by the platen roller 5.

When magenta printing ends and the end of the paper is reached, a control means (not shown) detects this with a sensor and outputs a reverse transmission signal. In response to the reverse transmission signal, the platen roller 5 rotates in reverse to reversely feed the sheet 6 in the direction of arrow B.Next, the sheet 1 is moved to the position of the cyan IC in order to print in cyan. Cyan is printed in the same way as magenta. However, in order to prevent color shift in the transport direction, the print position detection means 9 detects the line spacing of magenta print that has already been printed, and adjusts the amount of paper feed.

That is, when the printing of the - line is completed, paper feeding is started, and when the next printing line is detected by the printing position detection means 9, paper feeding is stopped. This prevents color shift in the conveyance direction of the paper 6.

Furthermore, in the present invention, during the above printing, color misregistration is also prevented from occurring in the direction perpendicular to the conveying direction as follows.For example, as shown in FIG. Assume that the heating elements 6a-6e are shifted by one position to the right with respect to the heating elements 13a-13f.

Whether such a shift has occurred can be determined based on the data stored for each line for each color and the print position detection means 9.
This is done by comparing the print position detected by

In the case shown in FIG. 3, the cyan printing signal is not given to the heating element 13a (white signal), the signal that should normally be given to the heating element 13a is given to the heating element 13b, and the signal that should be given to the heating element 13b is is applied to the heating element 13c. That is, all of the data in the part is shifted to the right by one position. If the direction of shift is opposite, the data is shifted in the opposite direction. The above operation is performed for each line so that cyan printing does not deviate from magenta printing.

Next, printing is performed for yellow by the same operation as above.

Note that it is sufficient to provide the printing position detection means 9 for several heating elements, but the accuracy will be better if a larger number are provided. Furthermore, the smaller the distance between the print position detection means 9 and the print head 4, the more accurate printing can be performed.

The present invention can be applied to printers using electrostatic recording heads and electrophotographic printers using LED heads, as long as the recording apparatus forms one recorded dot by overlapping a plurality of printed dots.

[Effects of the Invention] The printer according to the present invention includes a print position detection means for detecting how far the print position in the direction perpendicular to the conveyance direction of the first color deviates from the normal position with respect to the print head, and Data shifting means is provided for shifting the data given to each printing means to the right or left based on the output of the position detection means. Therefore, there is no printing misalignment in the direction perpendicular to the paper conveyance direction.

In other words, it is possible to provide a highly accurate printer that is free from printing misalignment.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the structure of a printer according to an embodiment of the present invention, FIG. 2A is a plan view showing details of the print position detection means, FIG. 2B is a cross-sectional view thereof, and FIG. FIG. 4, which shows paper misalignment, is a perspective view showing the structure of a conventional printer. 4 is a print head, 5 is a platen roller, and 9 is a print position detection means. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A paper transport mechanism that transports paper forward or backward; printing means arranged at predetermined intervals in a direction perpendicular to the paper transport direction; A control means for applying a reverse signal to the paper conveyance mechanism to cause the paper conveyance mechanism to reversely feed; and a control means for detecting how far the printing position of the first color in a direction perpendicular to the conveyance direction deviates from the normal position with respect to the print head. A printer comprising: printing position detection means; and data shifting means for shifting data given to each printing means to the right or left based on the output of the printing position detection means. (2) The printer according to claim 1, wherein the printing position detection means detects the printing position of only a portion of one line of printing of the first color.