JP2007136954A - Printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem in a printer having laterally arranged print heads, wherein image quality degradation due to color unevenness in color printing is generated since many joints for a temporary stop are generated if printing is finished all at once when a cover is opened. <P>SOLUTION: Printing by all of remaining print heads is finished at the printing position of the most advanced print head when the cover is opened, and when the cover is closed, printing is resumed from the finishing position. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printing apparatus of a serial scan type that prints an image with scanning of a print head and appropriately copes with when the cover of the apparatus main body is opened. In particular, the invention is suitable for an inkjet printing apparatus using a plurality of heads.

  A serial scan type printing apparatus forms an image on a printing medium while reciprocating a carriage on which a print head is mounted. In recent years, the movement speed of the carriage has been increased in order to improve the printing speed, and the carriage mass has been increased by mounting a large number of print heads in order to improve the image quality, so the kinetic energy of the carriage during printing has also increased. There is a tendency. Along with this, the danger level when a human body comes into contact with the moving carriage increases.

Therefore, conventionally, a cover that covers the moving range of the carriage is provided on the main body of the apparatus so that the user cannot touch the moving carriage, and when the cover is opened, the movement of the carriage is immediately stopped. Safety measures were taken. In Patent Document 1, the printing operation is actively stopped at the moment when the cover is opened, the printing stop position and the image that has not been printed are stored, and the printing is performed after the cover is closed. A configuration has been disclosed in which printing is continued again from the stop position to achieve both safety and convenience for the user.
JP-A-5-147322

  In general, in an ink jet printing apparatus, since ink permeation gradually proceeds, discontinuity of the permeation state occurs when printing is temporarily stopped, and streaks appear on the printed matter. When a plurality of print heads are arranged side by side, such as color printing, not only the number of heads can be seen, but also there is a problem in that color unevenness occurs because the time difference when the colors are superimposed is not constant. In the conventional example, since the printing operation is stopped at the same time as the cover is opened, a plurality of regions having different color overlaps with the arrangement pitch of the heads are formed. As a result, color unevenness occurs and the image quality is significantly reduced.

  FIG. 5 is a diagram showing a state in which color unevenness occurs. FIG. 5a shows the position of the head and the state of the recorded image when the cover is opened and printing is paused. In the figure, symbol H denotes a print head, and four colors of K (black), C (cyan), M (magenta), and Y (yellow) are arranged in order. The case where the K head precedes and the Y head is the last will be described, but the essence of the description does not change even in the reverse direction. Since printing is stopped at the same time when the cover is opened, it can be seen that a plurality of regions having different color overlaps are formed. FIG. 5b represents the image formed after closing the cover. Since printing is resumed all at once from the time when the cover is closed, a plurality of regions having different color overlaps are formed. FIG. 5c shows an image recorded as a result of superimposing these images. In all regions, the colors are superimposed in the order of K, C, M, and Y, but color unevenness occurs because the timing of waiting for the pause is different.

  An object of the present invention is to provide a printing apparatus that sufficiently secures the safety of the user even in the case of color printing, does not sacrifice convenience, and minimizes the degradation of image quality during suspension. It is.

  In order to solve the above-described problem, the printing apparatus of the present invention drives a plurality of print heads arranged in parallel in a moving direction by moving means, and drives the print heads to thereby form an image on a printing medium. In a printing apparatus for printing, an openable / closable cover that covers a moving area of the print head, a detection apparatus for detecting opening / closing of the cover, and a print range setting for setting a print start position and an end position before starting a printing operation A cover open position storage device that stores the position of the most preceding print head when the cover is detected by the detection device after the printing operation is started, and the stored position. The print end position change device that sets the print of all the heads to finish and stops the print head movement after the print of all the print heads is finished. When the printing is temporarily stopped by a printing pause device constituted by a movement stop device, and when it is detected by the detection device that the cover is closed again, all from the stored position A print start position resetting device that sets the printing of the head of the printer to start, a print end position return device that resets the print end position to the end position set in the print range setting device before starting the printing operation, Printing is resumed by a print resuming apparatus configured with a movement resuming apparatus that resumes movement of the print head from the print start position.

  According to the printing apparatus of the present invention, all the print heads remaining at the print position of the most preceding print head when the cover is opened finishes printing, and when the cover is closed, printing resumes from the end position. Even when a plurality of print heads such as color printing are arranged side by side, the influence of image quality deterioration due to color unevenness can be minimized. Since the movement of the print head is also stopped immediately after the end of printing, the safety of the user is ensured.

  FIG. 6 is a diagram showing the effect of the invention. FIG. 6a shows the position of the head and the state of the recorded image when the cover is opened and printing is temporarily interrupted. The C, M, and Y heads continue to print up to the position of the K head when the cover is opened, and then the carriage is stopped, so no half-color overlap occurs. FIG. 6b represents the image formed after closing the cover. After the cover is closed, the printing is continued again from the position where the printing was completed, so that no half-color overlap occurs. FIG. 6c shows the state of an image recorded as a result of overlapping these. In all areas, colors are superimposed in the order of K, C, M, Y, and there is no color unevenness because there is no waiting for a pause due to halfway color overlap.

Example 1
As a serial scan type printing apparatus, for example, an inkjet printing apparatus includes a carriage on which a print head as a printing unit is mounted, a conveyance unit that conveys a printing medium (for example, recording paper), and a control for controlling these. Means. Then, the print head for ejecting ink droplets from a plurality of ejection ports is scanned in a direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) of the printing medium, and the printing medium is removed during a non-printing operation. Images are sequentially printed by being conveyed intermittently.

  FIG. 1 is a schematic perspective view of an ink jet printing apparatus according to the present invention. In the figure, reference numeral 1 denotes a carriage for holding a plurality of inkjet print heads H having a plurality of ejection openings, 2 denotes a main scanning belt for reciprocating the carriage 1 along a guide rod R, and 3a, 3b are The pulley 4 for rotating the main scanning belt 2 is a main scanning motor for rotating the pulley 3a. Reference numeral 5 denotes a printing medium, and 6a, 6b, 6c, and 6d denote rollers that convey the printing medium 5 while holding it. Reference numeral 7 denotes a cover which is provided so as to cover the moving area of the carriage 1 and can be opened and closed in the directions of arrows A1 and A2, and 8 is a cover open / close sensor which detects opening and closing of the cover 7.

  FIG. 2 is a schematic configuration diagram of a control system in the printing apparatus according to the present invention. In the figure, reference numeral 9 is a print control device, 10a, 10b, 10c, 10d are ejection control devices, 11a, 11b, 11c, 11d are print start position registers, and 12a, 12b, 12c, 12d are print end position registers. . Reference numeral 13 denotes a carriage control device that controls the position and speed of the carriage, and reference numeral 14 denotes a current position register that measures and holds the current position of the carriage. In the figure, the main scanning motor 4 is a pulse motor, and the current position register 14 counts command pulses to the pulse motor. Reference numerals 15a and 15b denote print range registers. When the print range is determined based on print data from a host computer (not shown), the print range registers 15a and 15b are set, and the print control device 9 is instructed to start one-line printing.

  The subsequent operation of the printing apparatus will be described with reference to the flowchart of FIG.

  A value obtained by adding the offset distance to the left end 15a of the printing range is set in the printing start position register 11 for each color (S102). Here, [n] represents an arrangement by color, and corresponds to K, C, M, and Y in the order of n = 0, 1, 2, and 3. The offset distance is the carriage position when each color head is located directly above the left edge of the paper. A value obtained by adding the offset distance to the right end 15b of the print range is set in the print end position register 12 for each color (S103). If the cover is open, it waits until it is closed (S104). Next, a position that is an acceleration distance before the start position of the K head is calculated as an approach start position (S105), and if the current position of the carriage is on the right side of the acceleration start position, it moves to the acceleration start position (S106, S107). . The acceleration distance is set so that the carriage speed reaches the target speed before the K head reaches the print start position. The carriage is accelerated and a printing operation is started (S108). If the cover is not opened until the carriage reaches the print end position of the Y head (S109, S110), the carriage is decelerated and printing ends (S111, S119).

  On the other hand, if the cover is opened between the start of printing and the end of printing, the position obtained by subtracting the offset of the K head from the current carriage position + α is set as the right end position of the new printing range (S114). . The print end position register 12 is updated based on the new right end position (S115). When the carriage reaches the print end position of the Y head, the carriage is decelerated and printing is interrupted (S116, S117). The reason why + α is added in S114 is to consider the distance that the carriage travels during the required time from S112 to the end of S115. If the cover is opened before printing starts, the printing end position of each color is set to the left of the printing start position so that no printing is performed, and then the carriage is decelerated and printing is interrupted (S113). When printing is interrupted, the printing start position of each color is set immediately to the right of the printing end position (S118), and the process returns to the printing procedure after S103 again. By repeating the above procedure until reaching S119, one-line printing including pause and continuation is completed.

  In the above description, the carriage travels from the left side to the right side. However, even if the direction is reversed, the essence of the description remains unchanged if the left and right sides are appropriately interchanged.

  FIG. 4 is a diagram showing the position of the carriage in a time series including the temporary interruption of printing. In the figure, the horizontal axis represents time, and the vertical axis represents the position of each head. Ps is a print start position, and Pe is a print end position. The graph has four lines and represents the K, C, M, and Y head positions from the top. The carriage starts to move from the front by an acceleration distance from Ps, and printing is started sequentially from the head that has reached Ps. When the cover is opened at time T1, the head positions of K, C, M, and Y are Pk, Pc, Pm, and Py, respectively.

  The wavy line represents the operation in the conventional example. It can be seen that all heads stop printing at time T1, and then all heads resume printing at time T3. On the other hand, the solid line represents the operation of the present invention. When the cover is opened at time T1, all the remaining heads continue to print up to the position Pk of the K head at that time, and printing ends at time T2 when the Y head reaches Pk, and the carriage is stopped. When printing is resumed at time T3, all the heads sequentially reach Pk and printing is started. When viewed graphically on the graph, the interruption line is perpendicular to the time axis at the time T1 in the conventional printing apparatus, whereas the interruption line is perpendicular to the position axis at the position Pk in the printing apparatus of the present invention. That characterizes the difference between the two.

  In the printing apparatus of the present invention, the carriage movement time is increased by (T2-T1) as compared with the conventional example. This time is obtained by dividing the distance between the most distant heads by the carriage speed, and becomes shorter as the carriage speed increases. For example, if the distance between the heads is 24.3 mm and the carriage speed is 25 inches per second (635 mm per second), it is 0.038 seconds, which is a sufficiently acceptable time.

(Example 2)
In the first embodiment, the motor 4 is a pulse motor, but it can also be applied to a printing apparatus using a DC motor. Combine linear encoders to detect carriage position and speed. The linear scale is fixed in the main scanning direction, and the encoder head is mounted on the carriage. The carriage control device 13 performs feedback control by feedback from the encoder. The current position register 14 is configured to count pulses from the encoder.

1 is a schematic perspective view of a printing apparatus according to the present invention. It is a schematic block diagram of the control system in the 1st Embodiment of this invention. It is a flowchart explaining operation | movement of the control system in the 1st Embodiment of this invention. FIG. 5 is a diagram illustrating a time-series position of a head when printing is temporarily stopped. FIG. 10 is a diagram illustrating a printing result when printing is temporarily stopped by a conventional printing apparatus. FIG. 10 is a diagram illustrating a printing result when printing is temporarily stopped by the printing apparatus of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Carriage 2 Main scanning belt 3 Pulley 4 Main scanning motor 5 Medium to be printed 6 Sub scanning conveyance roller 7 Cover 8 Cover opening / closing sensor 9 Print control apparatus 10 Discharge control apparatus 11 Print start position register 12 Print end position register 13 Carriage control apparatus 14 Current position register 15 Print range register

Claims (1)

  In a printing apparatus that prints an image on a printing medium by moving a plurality of print heads arranged in parallel in the movement direction by a moving means and opening and closing the movement area of the print head. A free cover, a detection device for detecting opening and closing of the cover, and a print range setting device for setting a print start position and an end position before the start of a print operation, and the cover by the detection device after the start of the print operation If an open state is detected, a cover open position storage device that stores the position of the most preceding print head, and a print end that is set so that printing of all the heads is completed at the stored position A print pause device comprising a position change device and a movement stop device that stops the movement of the print head after printing of all the print heads is completed. Then, the printing is temporarily stopped, and when the detection device detects that the cover is closed again, the setting is made so that printing of all the heads starts from the stored position. A print start position resetting device, a print end position return device that returns the print end position to the end position set in the print range setting device before the start of the printing operation, and the movement of the print head is resumed from the print start position. A printing apparatus configured to resume printing by a print resuming apparatus including a movement resuming apparatus.

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