JPH04369158A - Serial scanning printer - Google Patents

Abstract

PURPOSE:To obtain a smooth picture without any joint. CONSTITUTION:Recording is implemented and finished in one or both main scanning directions while repeating main scanning and subscanning. A detection means 13 detects serial print information in the subscanning direction as relative information in the subscanning direction for a recording head and a print position on a recording medium. Adjustment means 11, 12, 14 adjust the relation of position between the print position and the recording head to a preset relation of position.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial scanning printer, and more particularly to a serial scanning printer having image seam (streak) removal means. For example, it is applied to graphic printers, copying machines, fax machines, etc.

0002

2. Description of the Related Art Conventionally, a recording head is provided with a plurality of nozzles arranged in the vertical direction, and this recording head is used for main scanning in a horizontal direction perpendicular to the feeding direction of a recording medium, and by feeding the recording medium, a sub-scanning is performed. In a recording apparatus that performs recording, it is difficult to record in such a way that the seam between the bottom row of characters printed in the first main scan by the recording head and the top row of characters printed in the next main scan is inconspicuous. In other words, if the bottom line of the first main scan print and the top line of the next main scan print overlap too much, the density of that part will increase and the joint will become black and stand out. If the amount is decreased, white streaks become noticeable due to variations in paper feed, etc., and stable and clear image quality cannot be maintained.

In order to solve this problem, an "ink jet recording apparatus" has been proposed in, for example, Japanese Patent Laid-Open No. 107975/1983. This publication relates to an inkjet recording apparatus that is capable of producing stable images in which the transitions between scans are not noticeable. Figure 5
(a) and (b) are diagrams for explaining the occurrence of streaks in the transition portion between each scan. Serial printers generally repeat the operation of printing area A in one main scan and printing area B in the next scan, as shown in Figure (a), but there is a streak at the boundary between A and B. Therefore, in the above-mentioned Japanese Patent Application Laid-Open No. 60-107975, A
and B overlap, and the overlapping area is divided into two scans. However, there are problems in that sufficient effects cannot be obtained if the printing speed is slow and the paper feeding accuracy is poor.

Among pixel type hard copy devices that form characters and figures with a plurality of dots, serial scanning type hard copy devices print one line of 48 dots in one main scan, for example.
The paper is fed by 48 dots and the next 48 dot row is printed, which is repeated to create continuous characters and figures spanning rows. In recent years, the resolution of pixel-type hard copy devices has increased to 300 dpi (300 dpi per inch).
dots) and 400 dpi are becoming common. 300
For dpi, the distance between dots (dot pitch)
is approximately 85 microns.

Therefore, in the case of the above example, the pitch between the 48th dot line of the previous line and the 1st dot line of the next line cannot be changed until the paper is fed accurately by 85 x 48 = 4080 microns. is 85 microns, and a smooth image with no seams can be obtained. However, the actual paper feeding accuracy varies by tens of microns or more, and streaks due to excessive overlapping of dots and white streaks due to gaps between dots appear every 48 dots, significantly deteriorating image quality. In order to solve this problem, several software approaches have been made to improve the recording method, as proposed in the above-mentioned Japanese Patent Laid-Open No. 60-107975, but these are not sufficient. There is also a method to mechanically increase paper feeding accuracy, but it is expensive, and it is difficult to maintain accuracy when the thickness of the paper changes or the humidity changes.

[0006]

[Object] The present invention was made in view of the above-mentioned circumstances, and an object of the present invention is to provide a serial scanning printer that can produce seamless and smooth images.

[0007]

[Structure] In order to achieve the above objects, the present invention provides (1)
The printing operation is performed in one or both directions of the main scanning direction while repeating the operation of reciprocating the printing head (main scanning) and moving the printing head or the printing medium by a predetermined amount in a direction perpendicular to the main scanning direction (sub scanning). , in a serial scanning printer that completes recording of a certain area, a detection means that detects the previous print information immediately after sub-scanning as relative information in the sub-scanning direction between the print head and the printing position on the recording medium. and adjusting means for adjusting the positional relationship between the printing position and the recording head to a preset positional relationship, and further, (2) the adjusting means displacing the recording head in the sub-scanning direction. furthermore, (3) the adjustment means makes the adjustment by controlling the paper feed amount; further, (4) the adjustment means displaces the recording head in the sub-scanning direction. (5) In (2) above, a laminated electrostrictive vibrator is used as the displacement means for displacing the recording head. It is characterized by its use. Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a configuration diagram for explaining an embodiment of a serial scanning printer according to the present invention. In the figure, 1 is a recording head, 2 is a scanner, 3 is a laminated piezo element, and 4
is a carriage, 5 is a carriage guide, 6 is a pivot pin, 7 is a platen, 8 is a timing belt, 9 is a motor, 10 is a recording paper, 11 is a motor driver, 12 is a piezo driver, 13 is a position detector, 14 is a controller be. The scanner 2 is, for example, an A-Si equal-magnification sensor or a CC sensor.
As shown in FIG. 2, the D scanner is arranged so that the lowest end of the printed image is located on average near the center of the sensor array, so that the lowest end position of the image can be recognized from the address output of the sensor.

The operating procedure will be explained below. ■Print one band information by main scanning. ■Perform paper feed (LF). (2) After the carriage returns, the scanner 2 detects the lowest position of the serially printed band image. (2) The detected information is encoded and the controller 14 performs arithmetic processing. ■ Drive the piezo driver 12 or the piezo driver 12 and the motor driver 11, and drive the recording head 1 and the recording paper 1.
Adjust the relative position to 0.

[0010] When adjusting by displacing the recording head in the sub-scanning direction (claim 2); the paper feed amount usually has a normal distribution with respect to a standard value (median value or average value). Therefore, it is sufficient to adopt a configuration that can apply to the recording head a displacement sufficient to correct the variation within a certain range in the positive and negative directions relative to the standard value. A configuration example is shown in FIG. 3. The recording head 1 is rotatably mounted around a fulcrum 6, and is supported by a tension spring 15.
It is brought into contact with the laminated piezo element 3 by. The laminated piezo element 3 is displaced in the thickness direction in proportion to the voltage. The laminated piezo element 3 is suitable for this device because it can obtain n times the displacement with the same voltage in n layers, for example, compared to a single layer piezo element. This is achieved by setting the number of stacked layers of Viezo and the maximum value of the driving voltage so as to provide a displacement within a range (-δ to +δ) that can correct the variation in the paper feed amount.

In the case where the adjustment is made by controlling the paper feed amount (Claim 3); in this case, the configuration is such that it can move in two directions, forward and backward, in the paper feed direction, and the paper feed (LF) resolution (minimum paper feed amount). The finer the paper feed (LF) resolution, the better the alignment accuracy, but an appropriate value should be selected in consideration of cost. In the case of controlling both the displacement of the recording head and the paper feed amount (Claim 4); Claim 2 is effective when the paper feed amount is normally distributed and the median value does not change, but in reality, users Because the thickness, friction, etc. differ depending on the type of paper, the median value of the paper feed amount may deviate from the designed value. Therefore, errors may accumulate in the positive or negative direction of the feed, and may not be able to catch up with head position adjustment alone.

To explain specifically with reference to FIG. 4, for example, it is assumed that errors δ1, δ2, etc. accumulate for each paper feed, and the minimum paper feed amount (LF resolution) is exceeded at the n-th error δn. In this case, after the n-th LF operation, the motor driver 11 should correct the minimum paper feed amount Dp, and (δ1+δ2+...δn)-Dp=δ0 The head displacement amount should be applied by the amount of δ0 mentioned above.

[0013]

[Effects] As is clear from the above description, the present invention has the following effects. (1) Effect corresponding to claim 1: Since the position of the image is detected for each scan and the position of the image to be recorded next is aligned, which is a drawback of serial scanning printers, a seamless and smooth image can be obtained. It will be done. (2) Effect corresponding to claim 2: Since the recording head can be displaced by minute displacement steplessly, positioning can be performed with high precision. (3) Effect corresponding to claim 3: The paper feeding amount is controlled without the need for a new device as in claim (2) since the paper feeding device already exists. Since there is no limit on the feed amount, even if the feed amount deviates in one direction, it can be sufficiently corrected. (4) Effect corresponding to claim 4: Since the displacement of the recording head and the amount of paper feed are controlled, the accumulated error due to the deviation in the amount of paper feed can be sufficiently corrected with high accuracy, and it is possible to It is possible to obtain extremely good images regardless of paper thickness. (5) Effect on claim 5: The laminated piezo element can obtain a large displacement with a low voltage, and by using a region where voltage and displacement have a linear relationship, position adjustment can be performed with extremely high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram for explaining an embodiment of a serial scanning printer according to the present invention.

FIG. 2 is a diagram showing an example of reading by a scanner.

FIG. 3 is a diagram showing an example of a configuration for adjusting the recording head by displacing it in the sub-scanning direction.

FIG. 4 is a diagram showing paper feed amount and paper feed error.

FIG. 5 is a diagram for explaining the occurrence of streaks at the transition between each scan.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Recording head, 2... Scanner, 3... Laminated piezo element, 4... Carriage, 5... Carriage guide, 6... Pivot pin, 7... Platen, 8... Timing belt, 9... Motor, 10... Recording paper, 11... Motor driver , 12... Piezo driver, 13... Position detector, 14... Controller.

Claims (5)

[Claims] [Claim 1] A recording head is scanned back and forth (main scan),
A serial scanning type that completes printing in a certain area by repeatedly moving the print head or print medium a predetermined amount in a direction perpendicular to the main scanning direction (sub-scanning) while performing printing in one or both directions of the main scanning direction. In the printer, a detection means for detecting the previous printing information immediately after sub-scanning as relative information in the sub-scanning direction between the printing head and the printing position on the printing medium; 1. A serial scanning printer, comprising: adjusting means for adjusting the positional relationship to a preset positional relationship. 2. The serial scanning printer according to claim 1, wherein the adjusting means makes the adjustment by displacing the recording head in the sub-scanning direction. 3. The serial scanning printer according to claim 1, wherein the adjustment means performs the adjustment by controlling a paper feed amount. 4. The serial number according to claim 1, wherein the adjustment means performs the adjustment by using a combination of a displacement means for displacing the recording head in the sub-scanning direction and a control means for controlling a paper feed amount. Scanning printer. 5. The serial scanning printer according to claim 2, wherein a laminated electrostrictive vibrator is used as the displacement means for displacing the recording head.