JPH04177269A - Multi-color image forming device - Google Patents

Abstract

PURPOSE:To prevent color mismatching from being generated between images by a method wherein either the first recording means for recording an image while controlling a recording position of an image of each of colors or the second recording means for recording an image while controlling a recording position of an image subsequent to the second color is selected. CONSTITUTION:Image data for every color is sent to a control means 2 together with various parameters supplied from an image data supplying means 1. After a predetermined processing is performed, every color is recorded in a recording sheet 5 through a recording operation of the first or second recording means 3, 4. In the event that the first and second recording means 3 and 4 record multi-color image, control marks are set along a side edge of the recording sheet, thereafter a multi-color recording for repeating an image recording for every one color and overlapping some colors in reference to the control marks and a multi-color recording for concurrently recording the control marks when the first color data is recorded in a recording sheet are carried out. Selective changing-over of the first and second recording means 3 and 4 is selected by a selection executing means 6, the control means selects the first and second recording means 3 and 4 through this selection and any of the image recording is carried out. With such an arrangement, a color mis-matching between the images can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a multicolor image forming apparatus having a phase correction function for preventing color misregistration. This invention relates to a multicolor image forming apparatus that provides control marks that are repeatedly formed overlappingly on the recording paper and arranged along the side edges of the recording paper in the feeding direction of the recording paper, and that controls the image recording position by reading the control marks. .

[Prior Art] Conventionally, methods and devices for repeatedly overlapping and forming images of different colors on the same surface of recording paper for each color have been disclosed in Japanese Patent Application Laid-open Nos. 50-80713 and 1983. -11415
It is well known as described in Japanese Patent No. 8, Japanese Patent Application Laid-Open No. 59-105800, and has been put to practical use in thermal transfer printers, electrostatic color plotter printing devices, and the like. When recording multicolor images using these devices, if the positions of the superimposed images do not precisely match each other, color misregistration will occur and the quality of the formed image will deteriorate. The color shift mentioned above occurs when the paper feed roller does not accurately match the movement of the recording paper when moving the recording paper back and forth, or when the recording paper expands and contracts under the influence of tension, temperature, humidity, etc. Especially when forming an image on a large screen, the influence becomes significant and cannot be ignored.

For example, Japanese Unexamined Patent Publication No. 5
As disclosed in Japanese Patent Application No. 7-122455, Japanese Unexamined Patent Publication No. 57-124753, US Patent Application No. 4,401,024, and US Patent Application No. 4,485,982, control for detecting dimensional changes due to expansion and contraction of recording paper A method and device that places marks on recording paper, detects changes in the dimensions of the recording paper by reading these marks, and adjusts the recording timing signal for each line to form recording dots at intervals that follow the expansion and contraction of the recording paper. be.

[Problems to be Solved by the Invention] By the way, there are two methods of recording based on the above-mentioned control mark beats, i) and 11) described below.

i) First, control marks are recorded on recording paper, and then data for each color is recorded based on the control marks. According to this, for example, when recording black (K), cyan (C), magenta (M), and yellow (Y) data, it is necessary to perform back and forth recording operations five times including control marks. .

According to this, various proposals have been made to reduce as much as possible the deviation in overlapping colors due to expansion and contraction of the recording paper. For example, in the method disclosed in Japanese Patent Application Laid-Open No. 1987-53071, the formation position of a recording dot corresponding to a control mark position is determined by a signal read from the control mark, and
Other recording dots are corrected for color shift by positioning them every predetermined recording paper feed amount, starting from the recording dot position determined based on the control mark.

11), the recording of the first color and the control mark is performed simultaneously, and for the second and subsequent colors, data of each color is recorded based on the control mark, similar to the method described above.

The feature of i) above is that color blur correction can be performed in the same way for any color. That is, it is only necessary to prepare one means for correcting color misregistration based on the control mark, and specifically, one type of hardware and software is sufficient.

However, the operation for recording the control marks is an extra effort, resulting in wasted time.

Furthermore, the feature of the above item (it) is that since the control mark is recorded at the same time as the first color, there is no wasted time. However, while the first color image is completely synchronized with the control mark, the second and subsequent color images are recorded while reading the control mark with a sensor or the like. Therefore, when the recording paper expands and contracts in the paper feeding direction of the image, a difference occurs between the phase of the first color image and the phase of the second and subsequent color images with respect to the control mark, and There is a problem in that there is a risk of color shift occurring between images of the second and subsequent colors.

Furthermore, when recording is performed based on the control mark while being read by a sensor, a certain delay occurs between when the control mark is read and when the image is recorded. Therefore, in the method j1) above in which the control mark and the first color are recorded simultaneously, the colors after the second color are printed out of alignment with the image of the first color. This is a phenomenon that occurs because the above-described delay does not occur only when recording images of the first color.

This invention has been made in view of the above-mentioned points, and eliminates wasted time for recording control marks, and even when the recording paper expands and contracts in the paper feed direction of the image. It is an object of the present invention to provide a multicolor image forming apparatus in which there is no possibility of color misregistration occurring between a color image and images of second and subsequent colors.

[Means for Solving the Problems] That is, the present invention records a control mark on a recording paper, and determines the image recording position for each color of an image to be supplied based on image data consisting of a plurality of colors to be recorded according to the control mark. In the multicolor image forming apparatus to be controlled, after writing the control mark in the non-image forming area at the end of the recording paper, the control mark is read to control the recording position of each color image. When forming an image of the first color, the control mark is simultaneously written in the non-image forming area at the end of the recording paper, and by reading this control mark, the image of the second and subsequent colors is recorded. a second recording means for recording an image while controlling the recording position of the image; and designation of selective execution to the control means to selectively execute either the first recording means or the second recording means; The present invention is characterized by comprising a selection execution means for performing.

[Operation] In the multicolor image forming apparatus according to the present invention, when recording a multicolor image, control marks are provided along the side edges of the recording paper and arranged in the recording paper feeding direction. And, as the first function,
After recording this control mark, image recording is repeated for each color using the control mark as a reference, and multicolor recording is realized by overlapping a plurality of colors. In addition, as a second function, a control mark is recorded at the same time as the data of the first color is recorded on the recording paper, and the difference between the phase of the control mark and the first color and the phase of the control mark and the second color is calculated. Measurement is performed prior to actual recording, and based on the results, correction is made so that the phase of the control mark and the second color is equal to the phase of the control mark and the first color. Then, the user can select from the first and second functions according to predetermined judgments such as the usage time and the quality of the recording paper, thereby recording the image at the desired image quality and recording speed using a complex arithmetic circuit. (It can be realized without using

[Example code] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing the basic configuration of a color electrostatic plotter as a multicolor image forming apparatus of the present invention. Image data for each color is sent to the control means 2 along with various parameters necessary for recording. After predetermined processing is performed by the control means 2, each color is recorded on the recording paper 5 by the recording operation of the first recording means 3 or the second recording means 4.

As will be described later, these first recording means 3 and second recording means 4 are provided with control marks arranged in the recording paper feeding direction along the side edges of the recording paper, respectively, when recording a multicolor image. After that, there are two types of recording: multi-color recording, in which image recording is repeated for each color using this control mark as a reference, and multiple colors are superimposed, and multi-color recording, in which a control mark is recorded at the same time as the data for the first color is recorded on the recording paper. It is something to do.

The selection switching between the first recording means 3 and the second recording means 4 is performed by selection execution means 6, and this selection causes the control means to switch between the first recording means 3 and the second recording means. 4 is selected and one of the images is recorded. Further, the selection execution means 6 is adapted to select the recording means in accordance with the operation of the operation means 7.

FIG. 2 is a sectional view showing a schematic configuration of a color electrostatic plotter to which the multicolor image forming apparatus of the present invention is applied. The color electrostatic plotter shown in the figure forms a color image by overlapping four colors: black (K), cyan (C), magenta (M), and yellow (Y). This electrostatic plotter includes a paper feed section 11 that winds recording paper into a roll to record an image, a 7M reading sensor 12 that reads control marks (TM) described later, an encoder I3, and a latent image forming section 14. an electrostatic head 1B and a bad roller 15, a developing section L7 consisting of multiple color developing heads, a waste fluid absorbing section 1B that absorbs developer waste, a drive roller 19, an intermediate winding section 20, and a recording paper sheet of a predetermined size. It has an autocross cutter 21 that cuts the paper in a straight line, a paper discharge section 22, and the like, and is configured as shown in the figure.

The developing section 17 has black (K), cyan (C), black (K), cyan (C), etc.
, magenta (M), and yellow (Y), the developing heads 17 include 17C, 17, and 17Y.

Incidentally, when recording an image, the first color can basically be any color, and 1000% 17 is applied to the developing head 17.
M and 17Y are not limited to the illustrated arrangement.

In this example, the reason why the first color is recorded as black is 7.
This is because the S/N ratio is the best when the control mark is black when the M reading sensor is on white recording paper, and the same problem does not occur even if it is performed using other colors. below,
For convenience of explanation, the arrangement of the developing section 17 is black (K), cyan (C), magenta (M) from the latent image forming section 14 side.
), Yeo - (Y) (7) To the developing head 17,
17C.

17) It is assumed that they are arranged in the order of l and 17Y. Further, it is assumed that the paper feed section 11, pad roller 15, drive roller 19, and intermediate winding section 20 are driven by a drive system (not shown).

The basic operation of the color electrostatic plotter having such a configuration will be explained. First, recording paper is fed from the paper feed section 11 toward the paper discharge section 22. Then, the control mark data created inside the plotter or the first color data sent from an external computer etc. is processed to be suitable for the electrostatic head 1B, and the electrostatic head is controlled by a recording control section (not shown). 1B onto the recording paper. When the recording dots are formed in the latent image forming section 14 in this way, the recording paper is once conveyed in the paper ejection direction by the intermediate winding section 20, and the first color of the developing head of the developing section 17 of the color corresponding to the image data is The developing head, for example, the black (K) developing head 17 in this case, is contacted, and the developer is deposited thereon. Next, the waste liquid absorbing section 18 absorbs unnecessary developer and dries it, and then the sheet is rewound to its original position, that is, to the latent image forming section 14 . This operation is repeated multiple times, that is, for the required number of colors, and when the last data is developed, the recording paper on which the image has been formed is cut into a predetermined size by the auto cross cutter 21 and discharged. The paper is ejected to the section 22.

By the way, in such an image recording operation, in a color electrostatic plotter, accurate timing alignment of images of each color is important. Therefore, the control mark (TM
) is recorded on the recording paper, this control mark is read by the 7M reading sensor 12, and color images of each color are recorded in a superimposed manner in synchronization with the control mark. Details of this control mark will be explained below with reference to the block diagram of FIG. 3.

Basically, the data for each color is temporarily stored in the data buffer 23 from an external computer for each color, and then one line of data 24 (or one raster data) is extracted from there.
The signals taken as a unit are processed. Note that a predetermined amount of so-called "white data (data that is not developed)" is added to the head portion of the data in order to secure a control mark area (non-image forming area). The encoder pulse 25 is a pulse generated from the encoder 13, which is attached to a roller that rotates with the conveyance of the recording paper, in proportion to the conveyance speed of the recording paper, and is used to record one line per pulse. The pulse period is set.

The TM (control mark) phase difference correction value storage unit 26 stores in advance,
Alternatively, the value measured by the phase difference measuring means in the central processing unit (CPU) 27 is written, and this value is sent to the TM pattern generator 28 together with the encoder pulse 25.
Send to. The TM pattern generator 28 generates TM data to be added to the beginning of one line of data 24 based on the encoder pulse 25. And synthesis circuit 2
9 is the above C based on the signal from the 7M reading sensor 12.
According to the control of PU27, (1) TM pattern generator 2
8, (2) combine the data generated from the TM pattern generator with the beginning of one line of data 24, and (3) select only one line of data. conduct. (1) above is a method in which a control mark is first recorded and then an image of each color is recorded in synchronization with this control mark (hereinafter abbreviated as the method in Section 1).
When recording control marks in (2), the control mark is recorded simultaneously with the image recording of the first color, and the image is recorded in synchronization with the control marks of the second and subsequent colors (see Section 2 below).
(abbreviated as method), the control mark and the first color (abbreviated as
(3) is selected when recording a black image simultaneously, and (3) is selected when recording a color image other than (1) and (2) above.

The recording control section 30 controls operations up to actually recording the data obtained from the synthesis circuit 29 on recording paper, and is controlled by the CPU 27.

This recording control section 30 also controls the encoder pulses 25 and 7.
Based on the signal from the M reading sensor 12, line correction, which will be described later, is performed.

Next, the relationship between control marks and recording areas will be explained.

In this embodiment, the distance between the 7M reading sensor 12 and the electrostatic recording head IB of the latent image forming section 14 is set to 38 m11. Here, the value obtained by subtracting the above interval (38 m+s) from the distance between the control mark and the corresponding recording data will be referred to as the phase difference. Therefore, 7
If data is recorded instantly after the M reading sensor 12 reads the control mark on the recording paper, the interval between the control mark and the recorded data is 38 fins as described above, so the phase difference in this case is becomes O. however,
In reality, there is a certain delay between reading the control mark and recording. That is, the 7M reading sensor 12
These are the delay from when the recording control section 30 reads the control mark until it sends the detection signal to the recording control section 30, and from the time when the recording control section 30 receives the detection signal until it actually performs recording. In this embodiment, it has been actually measured that there is a delay of about 0.5 mm from when the control mark is read until when recording is performed.

By the way, in the above-mentioned second method, the control mark and the first color black (K) image are recorded at the same time, so the above-mentioned delay does not occur. That is, a black image is recorded with a phase difference of Omm with respect to the control mark. However, the second and subsequent colors, cyan (C), magenta (M), and yellow (Y), have a delay with respect to the control mark and are approximately -
It is recorded with a phase difference of 0.5 mm. Therefore, cyan, magenta, and yellow have a phase difference of about -0.5 mm with respect to black. Figure 4 shows this phase difference.
In the figure, the area that should be recorded in the same phase in the X direction is cyan (C
), magenta (M), and yellow (Y) are out of phase by -0.5 mm with respect to black (K).

Therefore, in order to eliminate this phase difference, a phase difference measuring means described below and a phase difference correcting means based on the results obtained by this phase difference measuring means are required.

First, regarding the phase difference measuring means, FIGS. 5(a) to (
This will be explained with reference to d). FIG. 5(a) shows the relationship between the control mark and a normal image, and the lower side of the figure is the non-image forming area where the control mark TM is written.

First, seven control marks (Al to A7) are recorded using the usual TM recording means (FIG. 5(b)). Next, the recording paper is returned to one end, and seven pieces of data having the same shape as the control mark are recorded in black using a normal recording means for recording based on the control mark, with A1 to A7 as the reference (Fig. 5). (C)).

However, the recording position is different from the normal recording position and is the same position as the control mark (B1 to B7). Next, the recording paper is rewound again, and the 7M reading sensor 12 reads Bk (i-1
7) to Ak (i-1 to 7) (FIG. 5(d)).

Here, if the measured values are L1 to L7, then Lk - Bk
-Ak (k-1 to 7). The above measured values L1 to L7
Among them, the average value L (
av, ). Finally, the phase difference correction value φ−L (a
v, ) 38 (mm) and store it. This 381 is the distance between the reading sensor 12 and the latent image forming section 14.

Here, the above interval (Ll) is determined by the 7M reading sensor 12.
The procedure for measuring is as follows. That is, CPU2
7, the recording paper is rewound in advance at a constant speed (VO)
The output of the 7M reading sensor 12 is monitored while being transported. When the B1 control mark is first detected, a first timer (not shown) is started therefrom, and then when the B2 control mark is detected, a second timer (not shown) is started in the same way. Thereafter, in the same manner, when the control mark B7 is finally detected, a seventh timer (not shown) is activated.

Next, when the control mark A1 is detected, the first timer is stopped, and the interval (Ll) is calculated from the time measured by the first timer and the recording paper conveyance speed (T1).

Ll-VOXTI Similarly, calculate the distance from B2-A2 to B7-A7. This measurement can be carried out by measuring only one point, for example, one point between A1 and B1 above, but in order to reduce measurement errors, measurements are taken at seven different points, and the maximum value of the measured value is Then, remove the minimum value and calculate from the remaining average.

In this way, the phase difference correction value φ is calculated as φ−L
(av,) −38(am).

Perform the above operations before recording an image. In the embodiment described above, this is performed during the initialization period that is performed after the color electrostatic plotter is powered on.

Next, the phase difference correction means will be explained. In the case of the second method, this phase difference correction means records the first color black with respect to the control mark by shifting it by a phase difference φ in the negative direction in the tJ6 diagram, or records the control mark with black. The data is recorded while being shifted in the positive direction in FIG. 6 by a phase difference φ.

By doing this, the control mark reading sensor 1
2 can be shared for phase difference measurement, thereby preventing cost increases. In addition, the phase difference for the second color and subsequent colors with respect to the control mark is made possible by recording a pattern with the same shape as the control mark in the first color, so it can be used without changing the 7M reading sensor 12, and there is no need to change the circuit. good. Furthermore, waste of recording paper can be minimized and measurement time can be shortened.

Incidentally, since the above-mentioned phase difference differs due to machine differences, which are errors caused by machine precision of each device, it is desirable that the phase correction value φ is set for each device.

For this reason, the phase difference must be measured i) once at the time of product shipment, and stored in the storage means in the device, such as ROM or non-volatile RAM.
If) the measurement is performed once when the device is powered on, or 111) the measurement is performed at any time prior to each recording. This is because the reading time of the 7M reading sensor 12, which causes the delay, may vary depending on the environment such as changes over time, temperature, humidity, etc. In the same embodiment, the nJ determination of the phase difference is performed when powering up the device in jj) above, but it can be changed in other cases of i) and 1ii) above depending on the application. Needless to say.

Next, line correction will be explained. The color electrostatic plotter is equipped with an encoder 13 that generates a signal synchronized with the movement of the recording paper in order to control the recording density so that a 64-line data string exists between control marks. The encoder 13 is, for example, 1/16 (+
One pulse signal (encoder pulse 25) is generated every (o+i/line).

The recording control unit 30 records one line of data for one pulse of the encoder 13. However, after recording control marks, if the recording paper expands or contracts in the recording paper transport direction due to tension, temperature, humidity, etc., or if the roller to which the encoder 13 is attached is even slightly eccentric and the encoder cycle is disturbed, This makes it difficult to accurately record 64 lines of data between control marks. Therefore, no correction is made until the line corresponding to the control mark deviates by less than two lines, and the following correction is performed for deviations greater than that.

That is, if the line data deviates by two or more lines more than the control mark due to reasons such as shrinkage of the recording paper, predetermined line data is deleted and unnecessary parts are deleted (see Figure 7 (a)). ). Alternatively, if the line data deviates from the control mark by two or more lines due to stretching of the recording paper, etc., copy and record the predetermined line data to compensate for the shortage (see Figure 7 (b)). ).

The above-mentioned value of 2 lines was determined based on experimental results and was found to be an acceptable amount in terms of image quality; however, depending on the recorded content, it may be corrected to a value larger or smaller than this value. is possible. It is obvious that this line change is easy as described above.

By the way, as mentioned above, the first method is characterized in that color shift correction can be performed in the same way for any color, and the second method is characterized in that the control mark is recorded at the same time as the first color, so it takes less time. It is characterized by the fact that there is no waste. Currently, when recording an image in which a magenta line drawing is drawn successively on a black line drawing, if the phases of the two are shifted, the shift becomes noticeable and a problem occurs. In this case, it is more advantageous to select the first method that does not cause color shift. Also, when recording an image with magenta characters written on a black image,
Even if the phases of the two are slightly shifted, no problem often occurs.

In this case, it is more advantageous to select the second method, which has a faster recording speed. Furthermore, for example, when recording paper with little expansion or contraction is used, line correction is not performed, so color misregistration is unlikely to occur between the first color and the second and subsequent colors. In this case, it is more advantageous to select the second method, which has a faster recording speed.

Therefore, in the present invention, a selection execution means is provided to enable selection between the first method and the second method for various reasons such as recording content, environment, recording paper, etc. for example,
In this embodiment, both are selected using the conditions and methods described below.

■ A switch is provided for the user to select whether the recording paper is subject to expansion and contraction due to tension, temperature, humidity, etc. or is not subject to expansion and contraction, and the recording paper is subject to expansion and contraction based on the selection signal from this switch. The first method is automatically selected for objects of this nature, and the second method is automatically selected for objects that are not subject to expansion or contraction, when the color electrostatic plotter is turned on.

(2) An operation panel that can be operated by the user is provided outside the color electrostatic plotter, and the first method and the second method can be selected using this operation panel.

■ In this embodiment, the order of recorded colors is black (K), cyan (C), magenta (M), and yellow (Y) from the latent image forming unit 14 side. For example, if the recorded data includes black data, In this case, data other than black must be recorded, but only when recording data. , the first method is automatically selected on the device side even if the second method is selected.

Regarding (■) above, it is known in advance that plain paper is generally easy to stretch, while Delmina paper, film paper, etc. are difficult to stretch. , for example, by switching a toggle switch.

Regarding (2), the operation panel is, for example, a liquid crystal panel, and is capable of selecting a plurality of modes. for example,
First, find an item for selecting the simultaneous printing mode of the control mark and the first color, black, and confirm the mode using the input confirmation key or the like. Next, using the input mode selection key, it is selected whether or not to execute the control mark and black simultaneous printing mode, and the input confirmation key is used to confirm the mode.

Note that the selections and combinations of (1), (2), and (2) described above can be considered for various containers, and can easily be realized by other selection execution means.

In this way, by providing a selection execution means, even if dimensions change due to expansion and contraction of the recording paper, it is possible to select between the ml method and the second method depending on various reasons such as image recording content, environment, recording paper, etc. By selecting , it is possible to prevent color misregistration in the recording paper transport direction in a multicolor image at low cost and with sufficient accuracy.

[Effects of the Invention] As described above, according to the present invention, there is no wasted time for recording control marks, and even when the recording paper expands and contracts in the paper feed direction of the image, the first color It is possible to provide a multicolor image forming apparatus in which there is no risk of color misregistration between an image and images of second and subsequent colors.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of a color electrostatic plotter as a multicolor image forming apparatus of the present invention, and FIG. M2 shows a schematic configuration of a color electrostatic plotter to which the multicolor image forming apparatus of the present invention is applied. 3 is a block configuration diagram showing details of the input image and control mark supply and the surroundings of the recording unit, FIG. 4 is a diagram showing the phase difference between the first color and the second and subsequent colors, and FIG. 5 ( a) to (d) are diagrams showing the relationship between control marks and normal images, Figure 6 is an explanatory diagram of the phase difference correction means, and Figures 7 (a) and (b) are diagrams explanatory of line correction. be. 1... Image data supply means, 2... Control means, 3.
...First recording means, 4...Second recording means, 5...
- Recording paper, 6... selection execution means, 7... operation means,
DESCRIPTION OF SYMBOLS 11... Paper feeding part, 12... TM (control mark) reading sensor, 13... Encoder, 14... Latent image forming part, 15... Electrostatic head, IB... Bad roller,
17...Developing section, 17K. 17cS17M, 17Y...Developing head, 18...
Waste liquid absorbing section, 19... Drive roller, 2o... Intermediate winding section, 21... Auto cross cutter, 22...
Paper ejection section, 23...Data buffer, 24...154
2 minute data, 25...encoder pulse, 26...
TM phase difference correction value storage unit, 27... CPU (central processing unit), 28... TM pattern generator, 29... synthesis circuit, 30... recording control unit. Applicant's representative Patent attorney Jun Tsuboi Figure 1 Figure 5 (a) Figure 5 (b) 〉 Σ Q and Figure 5 (C) Figure c; uA (d) L7 - distance N direction τ - correct tj target 6tll
J No. 7 0 Roro 2 Rai〉oritsu T'

Claims (1)

[Scope of Claims] (1) A multicolor image in which control marks are written on recording paper and the image recording position of each color of the supplied image is controlled based on image data consisting of multiple colors to be recorded according to the control marks. In the forming apparatus, after writing the control mark in the non-image forming area at the end of the recording paper, a first recording apparatus records the image while controlling the recording position of the image of each color by reading the control mark. When forming the first color image, the control mark is simultaneously written in the non-image forming area at the end of the recording paper, and by reading this control mark, the recording position of the second and subsequent color images is determined. a second recording means for recording an image while controlling the above; and a selection execution means for instructing the control means to selectively execute either the first recording means or the second recording means; A multicolor image forming apparatus comprising: (2) The control mark is recorded in one predetermined color among the plurality of colors, and the selection execution means selects the first color of the image to be recorded.
When the color data is the same as the predetermined one color, the second recording means is selected, and when the first color data of the image to be recorded is different from the predetermined one color, the first recording means is selected. The multicolor image forming apparatus according to claim 1, wherein the multicolor image forming apparatus selects and executes. (3) The multicolor image forming apparatus according to claim 1, wherein the selection execution means includes an external operation means. (4) a first signal generating means for generating an image recording signal for each color; a second signal generating means for generating an image recording signal for writing the control mark; and a delay circuit for delaying the image recording signal. and a control means for combining image recording signals from the first and second signal generating means, and when the second recording means is selected, recording the image from the first signal generating means. Claims 1 to 4 for delaying a signal
The multicolor image forming apparatus according to any one of the above. (5) The delay circuit detects the difference between the control mark and the first color image recording signal from the first signal generation means, according to information from the phase difference measuring means that measures the phase difference between the control mark and the image. When recording the image of the first color, the signal from the first signal generating means is combined with the second signal so that the phase difference is equal to the phase difference between the control mark and the image recording signal of the second and subsequent colors. 6. The multicolor image forming apparatus according to claim 5, wherein the multicolor image forming apparatus is delayed with respect to the signal from the generating means. (6) In a multicolor image forming apparatus, control marks are arranged along the side edges of the recording paper in the recording paper feeding direction, and the control marks are read by a control mark reading device to control the image recording position of each color. means for simultaneously recording the control mark in a non-image forming area on a side edge of the recording paper when recording a first color image; a phase of the control mark and the first color image; Based on the difference in phase between the mark and the images of the second and subsequent colors, when the control mark and the image of the first color are simultaneously recorded, the phase of the control mark and the image of the first color is the same as the control mark. A multicolor image forming apparatus comprising: means for correcting and recording the image so as to be equal to the phase difference of the second color image. (7) The multicolor image forming apparatus according to claim 6, wherein the phase difference measuring means measures the phase difference before the multicolor image forming apparatus enters a standby state after power is turned on. (8) The multicolor image forming apparatus according to claim 6, wherein the phase difference measuring means measures the phase difference immediately before each recording operation. (9) The reading device measures the phase difference when recording an image equivalent to the control mark at a control mark position ahead of the control mark in the paper discharge direction of the recording paper. The multicolor image forming apparatus described in . (10) The multicolor image forming apparatus according to claim 7, wherein the phase difference measuring means measures the phase difference in two recording operations including recording the control mark.