JPS6295548A - Positioning method for color image - Google Patents

Abstract

PURPOSE:To obtain a color image which has no color blurring by running a recording medium for a time required for moisture adjustment in which the expansion and shrinkage of the recording medium are almost saturated prior to the recording of the image. CONSTITUTION:The moisture absorption and drying of electrostatic recording paper become more remarkable at a part of distance when the recording paper is taken up around a winder 10 from a roll 2A than when the electrostatic recording paper 2 is rolled. For the purpose, the run time from when the electrostatic recording paper 2 is unwound from the roll 2A to when it is taken up around the winder 10 or its reverse time is set longer than the time required until the electrostatic recording paper absorbs moisture or becomes dry and its expansion or shrinkage almost reaches the saturation, thereby absorbing the expansion or shrinkage. The time up to when the expansion or shrinkage based upon variation in the moisture of the electrostatic recording paper almost reaches the saturation is greatly different depending upon the kind, moisture content, ambient temperature, etc., of the electrostatic recording paper, so those characteristics of electrostatic recording paper in use are measured previously and information on them is inputted to a controller. Consequently, a breadthwise color shift is eliminated and an excellent color image is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention involves repeatedly reciprocating a recording medium to a recording position.
The present invention relates to a color image alignment method for aligning images, particularly alignment in the width direction of a recording medium, in an apparatus that forms images of different colors at the same location and superimposes them to obtain a color image.

2. Description of the Related Art Conventionally, an apparatus shown in FIG. 4 has been known as an apparatus for obtaining color images. In FIG. 4, 101 is an electrostatic head, 102 is electrostatic recording paper, 102A is electrostatic recording paper, low paper 103 is a drive roller, and 1o4 is a plurality of developing units 104a to which toners of different colors are supplied. , 104
b, etc., 1o5 is a mark for alignment in the width direction (hereinafter referred to as CD mark), 106 is a mark for alignment in the feed direction (hereinafter referred to as MD mark), 107 is a rewinding motor , 10B is a winding motor,
109 is a head moving motor, and 110 is a wine rack that winds up electrostatic recording paper. Color image formation by this apparatus is performed in the following steps.

First, the electrostatic recording paper 102 is fed out from the roll 102A by the drive roller 103 and conveyed through the electrostatic head ICN. The electrostatic recording paper 102 that has been transported is transferred to the take-up motor 10.
8, it is wound up by a winder 110 with a constant tension.

During this conveyance of the electrostatic recording paper 102, the electrostatic head 101
A voltage is applied to form an electrostatic latent image of the first color on the electrostatic recording paper. At the same time, the developing device to which the first color toner is supplied (in FIG. 4, the developing device 104 to which blank toner is supplied) is raised and brought into contact with the electrostatic recording paper 102. Visualize. This process continues until recording and development of a predetermined length is completed, and all recorded image portions are wound up by the winder 110. next,
The roll 102A of electrostatic recording paper is driven in the rewinding direction of the electrostatic recording paper by a rewind motor 107, and the entire portion wound onto the winder 110 is rewound onto the original roll 102A. After that, record the next color image.

The electrostatic recording paper 102 is again moved to the 5 drive roller 10 for development.
:, a second color latent image is formed by the electrostatic head 101, and developed and visualized by a developing device 104b supplied with second color toner (for example, cyan toner).

At this time as well, the electrostatic recording paper 102 is wound up by the winder 110 until the recording of a predetermined length of image is completed, and when this is completed, it is rewound again onto the original roll 102A by the rewinding motor 1o. It will be done. The above steps one after another,
By repeating this process using a developing device supplied with different colors, images a of different colors are superimposed on the same position on the electrostatic recording paper 102, and a color image is formed. Note that the l@ number for forming images of different colors may be any number, but is usually determined by the characteristics of the toner or the characteristics of the developing device.

When obtaining a color image through the above steps, the most important thing to be careful about is color misregistration, and the painters of each color must be formed so that they overlap accurately at the same position.

When the electrostatic recording paper is repeatedly moved back and forth, the recording paper meanderes, expands and contracts3, so in order to correct this and align the image, it is usually done before the first image is formed. , a ■ mark 105 and an MD mark 106 are printed. The CD mark 106 is used to correct meandering of electrostatic recording, and when rewinding after printing the mark and applying voltage to the electrostatic head 101 for the next color, a photo sensor (not shown) is used to print the CD mark 106. (usually uses a COD array) detects the position of the CD mark 106, and if it deviates from the initial position, moves the electrostatic head 101 by the corresponding amount) to the gutter movement motor 109. It is moved in the width direction of the recording paper, and even if meandering occurs, it is corrected so that it always stays at the same position.

On the other hand, the MD mark 106 is for correcting the expansion and contraction of the electrostatic recording paper 102 in the sheet feeding direction. If it is growing, delay the recording cycle and
Furthermore, if the pitch of the IVID marks 106 is short, that is, if the electrostatic recording paper has shrunk, the pinch is measured and the color shift is corrected by recording faster than the PJT fixed recording cycle.

Problems that the issuing EA is trying to solve LJ There was a problem in that color shift occurred in the width direction of the paper.

The inventor of the present invention investigated the cause of this problem and found the following matter. That is, electrostatic recording paper is normally adjusted to a predetermined humidity and supplied in the form of a roll, but when this electrostatic recording paper is applied to a color image recording device as shown in FIG. 4 and fed out for recording, Depending on the surrounding humidity conditions, it absorbs moisture or dries, and expands and contracts not only in the feeding direction but also in the width direction.

With respect to expansion and contraction in the feeding direction, color shift is prevented by correction using the MD mark 106, but expansion and contraction in the lateral direction cannot be corrected even with the CD mark 106. This is because the CD mark 105 is corrected so that the recording start position in the width direction of the recording paper is constant, and no correction is made for expansion and contraction in the width direction of the recording paper. Expansion and contraction in the width direction causes large color shift on the side opposite to the recording start position, resulting in the above-mentioned problem.

As a method for eliminating color shift in the width direction due to expansion and contraction in the width direction, a CD mark 105 is placed on the electrostatic recording paper 1.
There is a method in which the head movement motor 109 is driven so that the electrostatic head 101 is always centered with respect to the screen. Although it is possible, the error is only divided into 9 parts on both sides, and it is not a fundamental solution. Also, since the expansion and contraction of recording paper is dependent on humidity, there are ways to make usage conditions very strict, but for those who actually use it,
It's a side thing. There are also recording media that use film that is less susceptible to humidity effects instead of paper, but this poses a problem because the cost is about 10 times higher than regular electrostatic recording paper. Ta.

The present invention has been made in view of the above-mentioned problems, and it is possible to use a simple method without controlling the humidity of the working environment, even if ordinary electrostatic recording paper is used as a recording medium. It is an object of the present invention to provide a color image alignment method that can obtain a color image without color shift.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a configuration in which, prior to recording an image, the recording medium is run for a period of time necessary to adjust the humidity so that its expansion and contraction approaches saturation. It is prepared. Here, the running for humidity conditioning of the recording medium is an idle feed in which the recording medium is reciprocated at the speed necessary for humidity conditioning without performing any recording on the recording medium, before recording on the recording medium. Alternatively, after printing a mark on a recording medium, the running speed when returning the recording medium to its original position for image recording is set to a slow speed necessary for humidity control. This can be achieved by doing so.

According to the present invention, with the above-described configuration, before recording an image on the recording medium, the recording medium is run in the surrounding atmosphere and is allowed to absorb moisture or dry until expansion and contraction due to changes in humidity approaches saturation. , during subsequent image recording, the recording medium will not expand or contract due to humidity changes, and recording will be possible in the width direction! By placing it on a stand, it is possible to prevent color shift over the entire width.

EXAMPLES The present invention will be explained in more detail below with reference to FIGS. 1 to 3.

FIG. 1 is a schematic diagram of a color image recording apparatus used to carry out the method of the present invention, in which 1 is an electrostatic head, 2 is electrostatic recording paper, 2A is a roll of electrostatic recording paper, and 3 is electrostatic recording paper. A driving roller for conveyance, 4 a developing means equipped with a plurality of developing devices to which toners of many colors are supplied, 5 a CD mark, 6 an MD mark, 7 a roll 28 rewind motor, 8 a winding υ A motor 9 is a motor for moving the IT head, and 10 is a wine cooler. These are fundamentally the same as the conventional one shown in FIG. 4, and the color image forming operation is also the same, so a detailed explanation will be omitted. A motor 3A for driving the drive roller 3, a rewind motor 7, and a take-up motor 8 are connected to a control device (not shown), and move the electrostatic recording paper 2 back and forth in the sequence shown in Fig. 3, c, d, and e. It is configured to move. Further, this color image recording apparatus is provided with a humidity sensor 11 for detecting humidity.

A signal from the humidity sensor 11 is input to a control device and is used to control the speed of reciprocation of the electrostatic recording paper, details of which will be described later.

FIG. 2 is a graph showing the relationship between humidity and time for a particular electrostatic recording paper, which was previously conditioned to a humidity of 60%. Therefore, even when this electrostatic recording paper is placed in an atmosphere with a humidity of 60%, no expansion or contraction occurs over time as shown by line 5o in FIG. 2, so that images without color shift can be obtained. However, when this electrostatic recording paper is used in an atmosphere with a humidity of 85 degrees, the electrostatic recording paper absorbs moisture in the air and begins to stretch, as shown by curve 51. When it rattles, the dimensional change stops.

The time required for the elongation to reach almost saturation is longer as the humidity difference is greater, as can be seen from the comparison with curve 52 showing the case of placing in a 75% atmosphere.

Conversely, as shown by curve 63, when the electrostatic recording paper is placed in a low-humidity atmosphere of 35 cm, the electrostatic recording paper dries, thereby causing shrinkage of the electrostatic recording paper.

In the apparatus shown in FIG. 1, the electrostatic recording paper absorbs moisture and dries as described above, so that the electrostatic recording paper 2 is unrolled from the roll state and wound onto the winder 10 from the roll 2A. It is noticeable in the distance between. Therefore, the electrostatic recording paper 2 is fed out from the roll 2A and is wound up by the winder 10, and vice versa. By allowing more time than necessary, expansion and contraction can be absorbed. The time it takes for the expansion and contraction of electrostatic recording paper to reach near saturation due to changes in humidity varies greatly depending on the type of electrostatic recording paper, moisture content, ambient humidity, etc. The characteristics have been investigated in advance, and this information is input into the control device (not shown) of the apparatus shown in FIG.

Next, the image alignment operation according to the present invention will be described with reference to FIG. 3, which is a graph showing the movement of the electrostatic recording paper over time. Figure 3a shows the conventional method, in which the electrostatic recording paper advances to print marks, returns to the original position, advances to form a black image, banks to the original position, and moves to form a cyan image. The process of moving forward and moving back to the original position is repeated, and each step of moving forward and moving back takes the same amount of time.

On the other hand, FIG. 3 shows an embodiment of the method of the present invention, in which the electrostatic recording paper from the two people in FIG. It is wound up by the winder 10.

At this time, no recording is performed using the electrostatic head.

This forward movement is called emptying. The forward speed during emptying is determined by the detected value of the humidity sensor 11. That is, when the humidity sensor 11 detects, for example, 85 inches, the unloading speed at this time is the time required for the electrostatic recording paper to reach almost saturation as shown by A in FIG. It is designated to run. After blank printing is completed, it is returned to its original position, and then, as in the conventional method shown in FIG. is formed. Also, if the humidity is 75 degrees, the emptying time will be shorter than when it is 85 degrees, as shown in Figure 3 C, and the emptying time will be shorter than the time shown in Figure 2 B. After that, it moves forward to print marks, moves back, moves forward to form a black image, moves back, and repeats the operations to form a color image. In this way, prior to image formation,
The purpose of providing the blanking time is that the expansion and contraction of the electrostatic recording paper is almost saturated, that is, after the electrostatic recording paper has been conditioned to that atmosphere, mark printing and image formation are performed, so the electrostatic recording paper When repeatedly reciprocating, the expansion and contraction in both vertical and horizontal directions is not affected by humidity, and the absolute dimensions in both vertical and horizontal directions match in each cycle, resulting in no color shift.

Figures 3d and 3e show a second embodiment of the invention. In this embodiment, first, the electrostatic recording paper is advanced to print marks. Next, after printing is completed, the electrostatic recording paper is placed in a winder.
When rewinding from 10 onto the original roll 2A, the speed of the backing is slowed down, and during this running, the electrostatic recording paper absorbs moisture and expands and contracts due to drying, bringing it into a nearly saturated state. This backing speed is determined from the detected value of the humidity sensor 11 based on the characteristics shown in FIG. For example, Figure 3d shows the case where the humidity is 86 degrees, and e shows the case where the humidity is 76%.
It took longer when the humidity was 86 degrees. Of course, when the humidity is 60%, no expansion or contraction occurs, so backing is performed at a normal speed. After slow banking for humidity control, the process of moving forward to form a black image, back, moving forward to form a cyan image, banking, etc. is repeated, and a color image is formed. In this method, unlike the methods shown in c and d that provide a blanking time, when rewinding after printing a mark, it is rewound slowly over time, so the absolute dimension in the vertical direction is The horizontal dimension is stable, and there is no color shift, although it differs between the image formation and the subsequent image formation. Note that even if the absolute dimension in the vertical direction changes, M
Since the pitch of the D mark 6 is measured and corrected, no color shift occurs.

In the above embodiments, the empty printing time or the back time after mark printing is based on the time A or B at which saturation is almost reached in the graph of FIG. 2, but these can be changed depending on the design concept. . For example, in order to completely eliminate color shift, it is sufficient to slowly increase the time so that the position approaches the saturation point further than the positions A and B in FIG.

In addition, if a color shift of the opposite degree is allowed, for example, if an error of several hundred μm is allowed for a recording width of 1 o○○, the time required to achieve about 50 to 70% of the saturation point is You can empty it or pack it by applying .

Further, in the above embodiment, the humidity is detected and the emptying time or backing time is set according to the humidity change.
The relationship between humidity and emptying time or backing time does not necessarily need to be set strictly, and may be set roughly in stages, such as setting a time for a certain humidity range.
Furthermore, a certain amount of emptying time or backing time which is always sufficient regardless of humidity may be provided. but,
It is preferable to configure the blanking time or backing time to be set depending on the humidity because the overall image forming time can be shortened.

The humidity sensor 11 used in the above embodiment may be of an analog type or may be of a switch type that can only measure a certain point. This point is 7.
When using a humidity sensor that can only measure 5% and 75%, by arranging multiple humidity sensors with different characteristics, you can set the emptying time or bank time in stages. ~4 pieces are sufficient for use.

Further, the position of the humidity sensor is not limited to being installed inside the device as shown in the figure, but may be installed outside. Furthermore, instead of controlling the emptying time or backing time in accordance with the detection signal of the humidity sensor, an operation switch is provided that allows the operator to manually set these times. Good too. In other words, since humidity fluctuations do not change drastically during the day, it is possible to determine whether large expansion or contraction occurs in the electrostatic recording paper by having the operator look at a regular hygrometer, rather than by placing a special humidity sensor. Determine whether or not it is necessary, and respond as necessary.

Similarly, the emptying time or backing time may be set using the operation switch.

Furthermore, although the above explanation is for the case where electrostatic recording paper is used, the method of the present invention is not limited to the case where electrostatic recording paper is used. Any method can be used, such as an electrophotographic method, a heat-sensitive method, or an inkjet method.

Effects of the Invention As is clear from the above explanation, in the present invention, prior to recording an image, the recording medium is run for a period of time necessary to adjust the humidity so that its expansion and contraction approaches saturation. Even when recording images by repeatedly moving the medium back and forth, the recording medium does not expand or contract due to moisture absorption or dryness, and the widthwise dimensions of the recording medium remain constant when recording images of each color, preventing color shift in the widthwise direction. This has the effect that it is possible to prevent this and obtain a good color image.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram of a color image recording apparatus used to carry out the method of the present invention, Figure 2 is a characteristic diagram showing the expansion and contraction characteristics of electrostatic recording paper over time in different humidity environments, and Figure 3 is a diagram of the present invention. FIG. 4 is a characteristic diagram of the running state of electrostatic recording paper according to an embodiment of the invention and a conventional example. FIG. 4 is a schematic configuration diagram of a conventional color image recording apparatus. 1... Electrostatic head, 2... River/electrostatic recording paper, 2
A... Roll, 3... Drive roller, 4
...Development means, 5...CD? -ri, 6
...MD? -Rewind, 7...Rewinding shimoter, 8...Rewinding shimoter, 9...
Head movement motor, 1o...winecoor, 1
1... Humidity sensor. Name of agent: Patent attorney Toshio Nakao and 1 other person/l Figure 2, Figure 3

Claims (3)

[Claims] (1) In a device that records a color image by moving a recording medium back and forth to a recording position multiple times and overlapping images of different colors at the same position, the expansion and contraction of the recording medium approaches saturation before recording an image. A color image alignment method characterized by running the image for a time required to adjust the humidity. (2) Registration of a color image according to claim 1, characterized in that running for humidity conditioning of the recording medium is achieved by empty feeding of the recording medium prior to printing alignment marks on the recording medium. Method. (3) The running for humidity conditioning of the recording medium is performed when returning the recording medium to its original position after printing the alignment mark on the recording medium. How to align color images.