JPH05278278A - Printer - Google Patents

Abstract

PURPOSE:To enable occurrenence of irregularity in printing such as a white streak, a black stsreak, etc., generated on a seam joint of printing to be prevented by a method wherein a carrying control means which changes a feed amount to a printing head of a medium according to a class of the medium to be recorded detected by a detecting means, is provided. CONSTITUTION:A media sensor 60 discriminates either of plain paper or OHP paper according to a transmitted light quantity through paper 13. Then, if a feed amount of paper is preliminarily set so that one line content of paper feed amount will be optimum when the paper 13 is plain paper, a black streak is never generated on a seam joint between a preceding printing part and a this time printing part, and optimum printing can be carried out. Further, when the paper 13 is the OPH paper, a paper feed amount of paper which is less by one dot content, i.e., one sixtieth line content of paper is fed. When the paper feed amount is decreased thus by one sixtieth line content, if the paper feed amount is set so that optimum printing is performed for the plain paper, by one line paper feed for printing on the OPH paper in the same way as printing on the plain paer, the white streak to be generated on the seam joint between the preceding printing part and the this time printing part is gone, and optimum printing will be able to be carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer for printing on a recording medium with a print head.

[0002]

2. Description of the Related Art Conventionally, in a carriage scanning type printer, a carriage on which a print head is mounted is moved to
After printing the print section, the print sheet is stepwise fed at a right angle to the traveling direction of the carriage, stopped at the next print section, and then printed. In such a conventional type, the print sheet is stopped at a position slightly deviated from the regular feed position due to the hatching of the print sheet feed motor, the difference in the slip amount of the feed roller caused by the type of the print sheet, etc. When you print
If the seam between the print part during the previous carriage operation and the print part during the current carriage operation does not match, and the print part during the previous carriage operation and the print part during the current carriage operation overlap, a black streak will occur at the seam part. Alternatively, when both printed portions are separated, white stripes occur at the joint portion, which is not preferable in terms of image quality.

In order to solve this problem, Japanese Patent Publication No. S58
As shown in Japanese Patent Publication No. 43028/1985 and Japanese Patent Publication No. 59/31949, at least one dot or more is made to overlap the lowermost printed portion of the previous printing and the uppermost printed portion of this printing in the print sheet feeding direction. In some printers, the lowermost printed portion of the previous printing and the uppermost printed portion of the current printing are alternately printed dot by dot.

[0004]

However, in the printer as described above, the overlap is always performed by the same amount regardless of the type of the print sheet, and therefore, the feed amount of the print sheet varies depending on the surface roughness of the print sheet. An error occurs, which may cause white stripes and black stripes to appear at the joint portion of the print.

For example, when the paper feed amount is adjusted according to OHP paper, printing on OHP paper is performed as shown in FIG.
However, a printed sheet with a rough surface compared to OHP paper, such as plain paper, has a smaller contact area with the paper feed roller and a smaller coefficient of friction than plain paper. It is easy to slip, and therefore the paper feed becomes insufficient. Therefore, when printing on plain paper, the seam between the print part during the previous carriage operation and the print part during the current carriage operation overlaps, and as shown in FIG. It may appear as uneven printing such as streaks, which may lead to deterioration of print quality.

Further, when the paper feed amount is adjusted according to the plain paper, the printing on the plain paper is good as shown in FIG. 7A, but when printing on the OHP paper, there is no slip with the paper feed roller. As a result, the paper is fed too much, and white stripes are generated at the joint between the print portion during the previous carriage operation and the print portion during the current carriage operation, as shown in FIG. 7B.

Further, in the case of OHP paper, the ink is OHP
Since it does not soak into the paper, white stripes tend to stand out due to over-feeding the OHP paper, but in the case of plain paper, the ink will not soak into the plain paper and the white stripes will not stand out easily. Streaks occur,
The print quality may be deteriorated.

In FIGS. 6 and 7, each dot for printing is indicated by a circle, and in order to distinguish the printing portion during the previous carriage operation from the printing portion during the current carriage operation, the current carriage The printed portion in operation is shown with diagonal lines.

The present invention has been made to solve the above-mentioned problems, and controls the feeding of the printing sheet to the optimum printing position by changing the feeding amount of the printing sheet according to the type of printing sheet. An object of the present invention is to provide a printer that does not cause uneven printing such as white lines and black lines that occur at a printing joint.

[0010]

To achieve this object, a printer according to the present invention comprises a conveying means A for conveying a recording medium to a print head, and a detecting means B for detecting the type of the recording medium. And a conveyance control unit C for changing the amount of feeding of the recording medium to the print head by the conveying unit A according to the type of the recording medium detected by the detecting unit B.

[0011]

In the printer of the present invention having the above construction, the detection means B detects the type of the recording medium, and the conveyance control means C is responsive to the type of the recording medium detected by the detection means B. The feeding amount of the recording medium by the transporting means A to the print head is controlled.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

2 and 3 show an ink jet printer embodying the present invention.

That is, in the center of the printer device 5, a vertically extending sheet conveying passage S for conveying the sheet 13 is defined by the guide plate 6. A paper feed cassette 28 that can be pulled out to the outside of the printer device 5 is arranged corresponding to the lower end of the paper transport passage S.
Can be accommodated. A paper feed roller 30 is arranged corresponding to the paper feed cassette 28, and the paper 13 can be taken out from the paper feed cassette 28. A carriage 20 for supporting the conventionally known inkjet head 10 is movably supported in the widthwise direction of the paper 13 by two guide shafts 22 in an intermediate portion of the paper transport passage S. A platen 12 is arranged on the opposite side of the sheet conveyance path S. The carriage 2
The timing belt 26 is fixed to position 0, and the carriage 20 is driven in the left-right direction via the timing belt 26 by driving the carriage motor 24.

A drive roller 32 and a nip roller 34 are arranged on the upstream side and the downstream side of the ink jet head 10 in the sheet conveying path S, and the upper and lower drive rollers 32 are driven by a sheet feeding motor 31 via a belt 33. Driven to rotate. Therefore, the paper 13 taken out from the paper feed cassette 28 by the paper feed roller 30
Are conveyed along the sheet conveying path S by the drive roller 32 and the nip roller 34, and the conveying means of the present invention is constituted by the drive roller 32, the nip roller 34 and the sheet feed motor 31.

A media sensor 60 is disposed downstream of the paper feed roller 30 in the paper transport passage S. The media sensor 60 includes a light emitting diode 60a and a phototransistor 60b disposed with the paper transport passage S interposed therebetween. And the detection means of the present invention.

A plurality of suction holes 40 are formed on the sheet conveying path S near the platen 12 facing the ink jet head 10. A fan holder 46 made of synthetic resin or the like that is in communication with the suction holes 40 and has excellent airtightness is continuously provided on the back surface of the platen 12, and a fan motor 42 drives a rear end of the fan holder 46. A fan 44 is attached.

A diverter 48 for branching the transport path is disposed downstream of the ink jet head 10 in the paper transport path S so as to rotate about a shaft 76 as a fulcrum by the operation of a solenoid 70. Transport passage S
The recorded sheet 13 that has been conveyed along the conveyance path A
Or, it is sent to either B. The transport path B is provided with a remelt platen 52 for performing heat treatment. The remelt platen 52 is provided with a remelt platen heater 54 and a thermistor 38 used for controlling to keep the heating temperature constant. Further, in the transport paths A and B, a drive roller 32 and a nip roller 34 for transporting the recorded paper 13 are provided similarly to the paper transport path S.

Next, the block configuration of the control unit of this embodiment will be described with reference to FIG. That is, the control unit of the ink jet printer of this embodiment is composed of the central control unit 17 (hereinafter referred to as CPU 17) including a well-known microcomputer, etc., and constitutes the conveyance control means of the present invention. A memory 72 and a media sensor 60 are connected to the CPU 17, and the carriage motor 2 is further connected via a drive circuit 74.
4, a paper feed motor 31, a paper feed roller drive motor 71, a solenoid 70, etc. are connected.

The operation of the printer thus configured will be described below with reference to the flow chart of FIG. 4 or FIGS.

First, in step 1 (hereinafter simply referred to as S1; the same applies to other steps), the CPU 17 causes the paper feed roller drive motor 71 to drive the paper feed roller 30.
Is driven to rotate and conveys the sheet 13 to the drive roller 32. Meanwhile, in S2, the media sensor 60
It is determined whether the paper is plain paper or OHP paper based on the amount of transmitted light of the conveyed paper 13.

When it is determined in S2 that the paper 13 is plain paper, the process proceeds to S3, in which the solenoid 70 is driven and the deverter 48 conveys the paper 13 in the direction of the conveyance path A so that the shaft 76 can be conveyed. Can be rotated counterclockwise about the fulcrum. Paper 13 conveyed by paper feed roller 30
Is conveyed and nipped between the drive roller 32 and the nip roller 34, and the platen 12 and its platen 12 are rotated and driven by the paper feed motor 31.
Is conveyed between the ink jet heads 10 facing each other and the suction holes 40 are generated by the negative pressure generated by the fan 44 there.
It is brought into close contact with the platen 12 side via.

In S4, the conveyed paper 13 is
By ejecting ink from the inkjet head 10 while the inkjet head 10 on the carriage 20 moves in a direction perpendicular to the paper conveyance direction by the carriage motor 24, a dot image for one line is formed. The roller 32 and the nip roller 34 feed the paper for one line, and
Print the dot image for one line. If the paper feed amount is set in advance so that the paper feed amount for one line by the drive roller 32 is optimum when the paper 13 is plain paper, the joint between the previously printed portion and the currently printed portion by the above operation is As shown in FIG. 6A, optimal printing is possible without the occurrence of black stripes at the seams. The operations of S4 and S5 are repeated until the printing of one page is completed, and an image is formed on the paper 13.

Further, the sheet 13 is guided to the conveyance path A by the deverter 48 and then sent to the sheet discharge tray 50 (S10).

When it is determined in S2 that the conveyed sheet 13 is an OHP sheet, the process proceeds to S6, the excitation of the solenoid 70 is stopped, and the deverter 48 is caused to move by the elastic action of the spring or the like. It rotates clockwise about the shaft 76 as a fulcrum so as to convey it in the direction B.
The sheet 13 conveyed by the sheet feeding roller 30 is conveyed and sandwiched between the driving roller 32 and the nip roller 34, and the sheet feeding motor 31 is driven to rotate to face the platen 12 and the platen 12 thereof. It is conveyed between the inkjet heads 10, and there the fan 4
Due to the negative pressure generated by 4, the platen 12 is brought into close contact with the suction hole 40.

At step S7, the transported paper 13 is
The ink jet head 10 on the carriage 20 is ejected from the ink jet head 10 by the carriage motor 24 while moving in the direction perpendicular to the paper conveyance direction, whereby a dot image for one line is formed. The paper feed amount is one dot less than the line amount, and the dot image for one line is printed. In the present embodiment, since the inkjet head 10 is composed of 60 dots per line, the paper feed amount is reduced by 1 dot, that is, by 1/60 line. In this way, by reducing the paper feed amount by 1/60 line, the paper feed amount for one line by the drive roller 32 is preset so that optimum printing is performed when the paper 13 is plain paper as described above. When set, the printing on the OHP paper does not cause white stripes at the joint between the previous printing portion and the current printing portion, which is caused by feeding the paper by one line like the printing on the plain paper. Optimal printing can be performed as in (a). The operations of S7 and S8 are repeated until the printing of one page is completed, and an image is formed on the paper 13.

Further, the sheet 13 is guided to the conveyance path B by the deverter 48. In S9, the paper 13 is reheated by the remelt platen 52. By this reheating treatment, by combining the individual ink droplets,
When printing on HP paper, since the ink does not soak into the paper, even if at least one dot is overlapped on the previously printed portion and the current printed portion, white stripes do not occur at the joint portion of the printing due to the hatching of the paper feed motor. After passing S9, the paper 13 is sent to the paper discharge tray 50 (S1).
0).

As is clear from the above description, the type of the recording medium is discriminated, the feeding amount of the recording medium is changed according to the type of the recording medium, and the recording medium is moved to the optimum printing position. By carrying out the control of feeding, it is possible to perform printing without causing printing unevenness such as white stripes generated at the seam of printing or black stripes due to overlapping of printing dots.

Incidentally, at right angles to the scanning direction of the carriage,
Alternatively, an inkjet printer has been described in which a print head having a plurality of nozzles arranged obliquely is mounted on a carriage and printing is performed while the carriage is moved relative to a recording medium. An ink jet printer, a thermal printer and a wire in which a print head having a single electro-multi-value deflection type nozzle that deflects at right angles or obliquely is mounted on a carriage, and printing is performed while moving the carriage relative to a recording medium. The present invention can be similarly applied to a carriage scanning printer such as a dot printer.

As the recording medium detecting means, the control for detecting the type of the recording medium using the media sensor 60 and changing the feed amount of the recording medium has been described. However, instead of this detecting means, a switch is used. It is also possible to use a panel or the like to instruct the type of the recording medium by key input or the like and change the feed amount of the recording medium.

Hereinafter, although not illustrated,
The present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[0032]

As is clear from the above description,
According to the ink jet printer of the present invention, the type of the recording medium is discriminated, the feeding amount of the recording medium is changed according to the type of the recording medium, and the recording medium is controlled to be fed to the optimum printing position. As a result, it is possible to perform printing without causing printing unevenness such as white stripes generated at the joints of printing and black stripes due to overlapping of printing dots.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of the present invention.

FIG. 2 is a basic sectional view of the present embodiment.

FIG. 3 is a partial perspective view of a recording machine instep and a suction mechanism of the present embodiment.

FIG. 4 is a flowchart of the present embodiment.

FIG. 5 is a block diagram of the present invention.

FIG. 6 is a dot configuration diagram in the case where a black streak is formed at a joint of printing according to the related art.

FIG. 7 is a dot configuration diagram in the case where a white stripe is formed on a seam of printing according to the related art.

[Explanation of symbols]

 10 Inkjet head 17 CPU 31 Paper feed motor 32 Drive roller 34 Nip roller 60 Media sensor

Claims (1)

[Claims] 1. A conveying means for conveying a recording medium to a print head, a detecting means for detecting the type of the recording medium, and a conveying means according to the type of the recording medium detected by the detecting means. And a conveyance control unit that changes the feed amount of the recording medium to the print head.