JPH0570149B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a reference detection method for multicolor image recording position alignment, particularly a reference detection method for multicolor image recording position alignment for recording a plurality of multicolor images in a superimposed manner. It is related to.

Conventionally, as such an image recording method, a multi-color image recording method is known in which an electrostatic recording process for each color of an original is sequentially performed and recorded on recording paper while aligning each color (registration).

As a device for recording such multicolor images, there is a color electrophotographic copying machine that uses a laser for full color (referring to a device that handles all types of natural colors in addition to a limited type of color, that is, false color). Are known. Such a copying machine is provided with a photosensitive drum 1 as shown in FIG. 4, the image light beam is deflected by a polygon mirror 5 and is irradiated via a lens 6. After the photosensitive drum 1 is cleaned with a cleaner blade 15, it is transferred to a primary charger 14.
The entire surface is charged, and then the charge is removed according to the above-mentioned image light beam, and an electrostatic latent image corresponding to the image is formed. This electrostatic latent image is developed with toner of cyan (C), magenta (M), and yellow (Y), which are complementary colors to the three primary colors of input light, namely red (R), green (G), and blue (B). Each color is developed by a developing station. Numerals 8, 9, and 10 are developing rollers for developing yellow, magenta, and cyan colors, respectively, and 18 is a developing cover.

On the other hand, the recording paper 20 stored in the recording paper storage box 11
is wound around the transfer drum 7 via a paper feed roller 12 and a guide 19, and the image developed for each color is transferred to a recording paper 20 via a transfer charger 13, and then passed through a paper discharge roller 16. Tray 17
is discharged to the top. In this case, the recording paper 20 is held by a holder (not shown) on the transfer drum 7, and the image is transferred to the same image position three times for each color. This 3
The transfer must be performed accurately to avoid misalignment, but registration errors may occur due to uneven rotation of the transfer drum and photosensitive drum, expansion and contraction of the recording paper held on the transfer drum, and poor retention. A defect occurs. Although this defect can be improved mechanically to some extent,
In order to record digital images with high precision using a dot configuration of lines/inch (4 lines/mm) or more, it is necessary to reduce the diameter of the dots that make up pixels to about 50 μm or less, and to reduce the distance between each dot. Considering that the pitch must be recorded in units of several μm, mechanical improvements such as those described above can only correct positional deviations of about 0.1 mm at best.

The present invention eliminates the above-mentioned conventional drawbacks, eliminates image shift when recording multiple images on the same recording paper, and provides multicolor image recording positioning that makes it possible to obtain high-quality images. The purpose is to provide a standard detection method for

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 shows a laser beam printer suitable for using the method of the present invention, which includes a yellow photosensitive drum 101, a magenta photosensitive drum 102, and a cyan photosensitive drum 103.
is used. An array laser 22 that generates three laser beams is used, and the laser beams generated by this laser are modulated by a laser modulator 3 for each of the three primary colors of the original, passed through an expander 4, and then deflected by a polygon mirror 5 and sent to a lens. 6 towards the photosensitive drum. The modulated light beam corresponding to the blue image is reflected by the mirror 107 and formed into an image on the yellow photosensitive drum 101, and the modulated light beam corresponding to the green image is directly focused on the magenta photosensitive drum 1.
02, and the modulated light beam corresponding to red is mirror 1
08 and are respectively imaged on the cyan photosensitive drum 103.

Each photosensitive drum 101, 102, 103 has cleaner blades 110, 112, 114, respectively.
Additionally, primary chargers 109, 111, and 113 are provided to clean the previous charging record, remove toner, and uniformly charge the entire surface of the photosensitive drum. Also, each drum has a developing roller 10 corresponding to that color.
4, 105, 106 are provided, and each roller is protected by a developing cover 130, 129, 128.
Further, a transfer charger 12 is provided at the lower part of each drum.
7, 126, 125 are arranged, recording paper storage box 1
The recording paper 20 stored in the recording paper 1 is conveyed between each photosensitive drum and a charger via a paper feed roller 12, paper conveyance rollers 120, 121, passes through a static eliminator 122, and is fixed by fixing rollers 123, 124. After that, it is ejected in the direction of the arrow.

In the above configuration, the laser beam modulated by the laser modulator 3 for the blue color of the original is deflected by the polygon mirror 5, and then deflected by the lens 6,
The image is formed on the yellow photosensitive drum 101 charged by the primary charger 109 via the mirror 107, and an electrostatic latent image corresponding to the blue color of the original is formed.
The image thus formed is developed by the developing roller 104 and transferred to the recording paper 2 via the transfer charger 127.
0 and recorded. In this case, reference marks (referred to as register marks in printing terminology) 201 are added at two locations at the leading end in the running direction of the margin W of the recorded image P as shown in FIG. 3A by appropriate means. This is formed on the photosensitive drum 101, for example, when forming an electrostatic latent image.

The reference mark added in this way is detected by a detection device (not shown) such as a photocoupler before recording the next color, that is, magenta color, and the position and line width of the reference line with respect to the predetermined reference shown in FIG. 3a are detected. X is calculated. The position of this reference line relative to a predetermined reference is expressed, for example, as a position relative to the registration timing of the recording paper, a laser modulation start timing, or a distance from the leading edge position of the recording paper. According to the position and width of this line, the recording position and width of the next color, ie, magenta and cyan, are adjusted. For example, the line positions are aligned by changing the start timing of laser modulation of the image signal on the recording paper using a method as shown in Japanese Patent Laid-Open No. 51-93221. The recording width can be adjusted, for example, by varying the frequency of the laser modulation clock of the image signal. In this way, the laser modulation of the next color image is controlled. By doing this, the registration of each color can be made to match the image P for the first color on the recording paper. The reference marks mentioned above may be marks 202 and 203 having shapes as shown in FIGS. 3b and 3c, respectively.

Furthermore, as shown in FIG. 4, it is also possible to provide a hole 401 at the reference position of the recording paper 20, or to use a hole 501 for conveying the recording paper as a reference mark.

The reference mark is detected during the recording process for each color, and correction is made using electronic software, so it can easily respond to changes in the quality of the recording paper due to changes in the equipment environment or changes to the recording paper at the user's request. This enables more stable and wide-ranging color image recording.

As described above, according to the present invention, two reference marks are formed on a photosensitive drum parallel to the axis of the photosensitive drum and separated from each other, developed with a developer, and the developed reference marks are transferred. The position of each color of the color multiplexed image on the plurality of photosensitive drums can be aligned by reading the two reference marks that have been read and obtaining information on the position of the line connecting the reference marks and the width of the line based on the read output. Since the reference for performing the printing is detected, when recording a plurality of multicolor images in a superimposed manner, it is possible to prevent misalignment of each color image and obtain a high-quality image, which is an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is an arrangement diagram showing the configuration of a color copying machine, FIG. 2 is a perspective view showing the configuration of a color copying machine used in the present invention, and FIG. 3a is an explanatory diagram showing the arrangement of reference marks. , FIGS. 3b, c, and d are explanatory diagrams showing other embodiments of the fiducial mark, and FIG. 4 is an explanatory diagram showing another example of the fiducial mark used in the present invention. 2, 22... Laser oscillator, 3... Laser modulator, 4... Expander, 5... Polygon mirror, 20... Recording paper, 101... Photosensitive drum for yellow, 102... Photosensitive drum for magenta, 1
03...Photosensitive drum for cyan, 104, 105,
106...Developing roller, 125, 126, 12
7...Transfer charger, 201, 202, 203, 2
04,401...Reference mark.

Claims (1)

[Claims] 1. A plurality of photosensitive drums are irradiated with different beams to form different electrostatic latent images, and the electrostatic latent images are developed with developers of different colors, and the electrostatic latent images are exposed on the same transfer material. In the reference detection method for multicolor image recording position alignment in which a color multiplex image is formed by multiple transfer to a plurality of photosensitive drums, two parallel to the axis of the photosensitive drums are spaced apart from each other on the preceding photosensitive drum of the plurality of photosensitive drums. form one reference mark, develop it with the developer, transfer the developed reference mark, read the two transferred reference marks, and position the line connecting the reference marks with respect to a predetermined reference based on the read output. and a reference for aligning the position and width of the color multiplexed image with the next color image on the plurality of photosensitive drums by obtaining information on the width of the line. Reference detection method for color image recording position alignment.