JPH02130566A - Color electrostatic recorder - Google Patents

Abstract

PURPOSE:To detect the amount of expansion/contraction and the amount of meandering and the ununiform feeding of a recording medium, to correct an image forming position, and to prevent color slippage by providing a mark detector, which detects hole marks provided along both edges of the recording medium, on each side of the recording medium. CONSTITUTION:The mark detectors 16a and 16b detect the positions of the hole marks 15a and 15b before the recording medium is carried in the direction shown by an arrow A and recorded by a multi-needle electrode recording head 5. A signal detected by a CCD sensor 20 in the mark detector 16 is inputted to a comparison arithmetic circuit, and comparison arithmetic operation is performed in relation to a reference signal from a reference signal circuit, thereby determining the amount of expansion/contraction and the amount of meandering of the recording medium. Then, the multi-needle electrode recording head 5 adjusts the recording position by shifting an image signal. This achieves accurate superposition and prevents color slippage.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color electrostatic recording apparatus that records images of different colors in succession on the same recording medium to obtain a color image.

2. Description of the Related Art A schematic diagram of a conventional color electrostatic recording apparatus is shown in FIG. 51 is a recording medium; 52 and 53 are winders for winding and unwinding electrostatic recording paper for reciprocating motion; winder 55 is a multi-needle electrode recording head disposed along the path of the recording medium; 54 is a pressing roller for maintaining contact between the recording medium and the multi-needle electrode recording head, 56 is a static elimination bar, 57, 58, 59, 60 are developing devices to which different color developers are supplied, and 61 is a used developer. A squeeze roller 62 and 63 is used to collect the agent, and 62 and 63 are a pressure roller and a drive roller for gripping and reciprocating the recording medium, and 64 is a drive source capable of forward and reverse rotation.

Next, the operation in this configuration will be explained. The recording medium 51 is conveyed in the direction shown by arrow A by a drive roller 62. At this time, an electrostatic latent image of, for example, a black image is formed within the effective screen of the recording medium 51 by the multi-needle electrode recording head 55, and electrostatic absorption is performed by the developing device 57 supplied with black developer. After the developer is visualized, the used developer is collected by a squeezer 61 and fixed. The recording medium 51 on which the black image has been recorded is wound up by the wine goo 53, and after the black image information has been recorded, the drive source 64 is reversed and the electrostatic recording paper 51 is rewound by the rewinder 52, and the rewinding is completed. Images of second, third, and fourth colors, for example, cyan, magenta, and yellow, are superimposed using the method described above.

In this way, an image in which four colors (black, cyan, magenta, and yellow) are superimposed can be obtained.

Problems to be Solved by the Invention However, with such a configuration, if the recording medium expands or contracts due to a change in atmospheric humidity and temperature after the electrostatic phenomenon of the first color occurs, the multi-needle electrode recording Since the minimum pitch of the recorded image, which is equivalent to the minimum pitch of the electrodes of the head, expands and contracts, there is a problem in that accurate superposition cannot be achieved and color misregistration occurs.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides mark detection means that is provided near a multi-needle electrode head and detects hole marks provided along both side edges of a recording medium; Using the information obtained by this detection means, the amount of expansion and contraction in the direction perpendicular to the conveying direction of the recording medium and the amount of meandering are calculated, and the expansion and contraction of the multi-needle electrode recording head and the timing of the recording start signal are adjusted according to the calculated amounts. This system has a configuration in which recording is performed by shifting the image signal.

Function: With the above-described configuration, the present invention can detect hole marks provided along both side edges of a recording medium even if the recording medium expands or contracts due to changes in ambient temperature and humidity during recording of each color. The mark detection means detects the mark position after the change, and heat energy is applied to the multi-needle electrode recording head to equalize the pitch between the electrodes according to the amount of expansion/contraction and meandering calculated from the detection results and the comparison amount with the reference value. Since the image signal can be shifted and recorded by adjusting the timing of the recording start signal and expanding and contracting the image signal, it is possible to align the superimposed images for each color.

Embodiments Hereinafter, preferred embodiments of the present invention will be described with reference to FIGS. 1 to 5.

FIG. 1 shows a schematic configuration of a color electrostatic recording apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a recording medium, 2 and 3 are wine handles for winding and unwinding the recording medium 1 in order to make it reciprocate, and 5 is a multi-needle needle arranged along the path of the recording medium 1. This is an electrode recording head. 4 is a presser roller for maintaining contact between the recording medium 1 and the multi-needle electrode recording head 5; 6 is a static elimination bar 7;
．． Developing units 8, 9, and 10 are each supplied with developer of a different color; 11 is a squeeze roller for collecting used developer; 12 and 13 are a pressing roller and a driving roller for gripping and reciprocating the recording medium. , 14 are drive sources capable of forward and reverse rotation. 15a and 15b are hole mark forming devices 18 for the first color, for example, hole marks formed by a laser and used for position correction for the second and subsequent colors; 16a and 16b are mark detectors for detecting the hole marks. . This mark detector 16 includes a CCD sensor 2 as shown in FIG.
The surface of the recording medium 1 is illuminated with an illumination means 21 such as a light emitting diode, and the reflected light is transmitted to a CCD sensor 2 using a same-magnification optical system 22 such as a SELFOC lens array.
0. 17 is a heater for expanding and contracting the multi-needle electrode recording head.

The recording medium 1 is conveyed in the direction shown by arrow A by a driving roller 12 and a pressing roller 13, and between them, a multi-needle electrode recording head 5 and a developing device, for example, a developing device 7 supplied with a black developer, are used to create an arbitrary black color. Image information is recorded. At this time, as the recording medium 1 is conveyed, the winding goo 3 winds it up, and at the same time, the winding goo 2 unwinds it. After all the black image information has been recorded, the drive source 14 is reversed and the electrostatic recording paper 1 is conveyed in the direction shown by arrow B by the drive roller 12 and the pressure roller 13. At this time, contrary to recording, the rewind 2 is used to wind the paper and at the same time the wine 3 is used to unwind. After rewinding the recording medium 1 to a predetermined position, the recording medium 1 is again conveyed in the direction shown by arrow A for recording, and then rewound in the direction shown by arrow B for each color of cyan, magenta, and yellow. Images are formed by superimposing them, and the final color image is formed by superimposing four colors.

Next, the positioning operation when superimposing images of each color will be explained in detail with reference to FIGS. 3 to 5.

Before the recording medium 1 is conveyed in the direction shown by arrow A in FIG. 1 and recorded by the multi-needle electrode recording head 5, the mark detector 1
The positions of the hole marks 15a and 15b are detected at 6a and 16b. As shown in FIG.
4 and is compared with the reference signal from the reference signal circuit 25 to determine the amount of expansion/contraction and the amount of meandering of the recording medium 1. That is, as shown in FIG.
A timer detects the time from the trigger signal output corresponding to the scanning start point until the detection signal of the hole marks 15a, 15b is output to detect the positions of the hole marks 15a, 15b. The amount of expansion and contraction is detected from the spacing between the parts 15b, and the amount of meandering is detected from their absolute positions.

Next, the following operations are performed to expand and contract the electrostatic recording paper 1. The reference signal circuit 25 has a table containing correlation data between the elongation of the multi-needle electrode recording head and the head heating energy as shown in FIG.

The comparison calculation circuit 24 compares the signals from the mark detection circuit 23 and the reference signal circuit 25, determines the amount of head heating energy corresponding to the expansion and contraction of the recording medium 1, and outputs it to the storage head heating circuit 26.

The recording head heating circuit 26 controls the heating of, for example, a coil heater or a ceramic heater installed on the side wall or inside the multi-needle electrode recording head 5 based on the signal from the comparison calculation circuit.

The multi-needle electrode recording head 5 is generally formed by fixing and molding linear electrodes arranged at equal pitches using a resin material, so it can be said to be a kind of composite material made of a metal material and a resin material. When thermal energy is applied to this composite material, both the linear electrode, which is a metal material, and the molded part, which is a resin material, expand thermally, but the coefficient of thermal expansion of the resin material is larger than that of the metal material. Because of their large size, the thermal expansion of the linear electrodes is minute within the thermal energy load range necessary for expansion and contraction of the multi-needle electrode recording head 5.
Changes in recording dot diameter are of little concern. Also,
Since thermal expansion and thermal contraction have a property of acting uniformly on the material, the pitch between the linear electrodes can be varied to an equal pitch.

Next, the following operation is performed for meandering of the recording medium 1. A correction signal is output from the correction circuit 27 to the recording control circuit 28 based on the meandering amount determined by the comparison calculation circuit 24. The recording position in the X direction is adjusted by adjusting the timing of the recording start signal from the multi-needle electrode recording head 5, and the recording position in the Y direction is adjusted by shifting the image signal with respect to the recording start signal.

By repeating the above operations, a predetermined color image can be formed, and the recording medium expands and contracts due to environmental changes during reciprocating transportation of the recording medium. Or, even if there is meandering due to reciprocating conveyance, color misregistration will not occur between the first recorded image and the subsequently recorded image.

In the above embodiment, the detection signal from the mark detector was used only to correct the expansion/contraction and meandering of the recording medium, but as shown in FIG. 5, the number of pulses between hole marks in the conveyance direction of the recording medium is counted and printed It may also be used to adjust feeding unevenness in the X direction by varying the timing period.

Further, the hole mark may be formed on the recording medium in advance, or may be formed not only by a single hole but also by a large group of a plurality of minute holes.

Effects of the Invention According to the color electrostatic recording device of the present invention, only one mark detector for detecting the hole marks provided along both side edges of the recording medium is provided on each side of the recording medium. It can detect the amount of expansion and contraction of the recording medium, the amount of meandering, and uneven feeding.
By expanding and contracting the multi-needle electrode recording head or correcting the image forming position based on the detection results, a color image without color shift can be obtained even if the recording medium is conveyed back and forth multiple times to form a color image. Moreover, since the hole mark is used, there is no mark trace left on the image forming surface unlike when the mark is formed by printing.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of a color electrostatic recording device according to an embodiment of the present invention, FIG. 2 is a sectional view of the position detection means, FIG. 3 is a control block diagram, and FIG. 4 is a diagram showing the energy applied to the recording head and the recording FIG. 5 is a correlation diagram of expansion and contraction of paper; FIG. 5 is an explanation of the operation for detecting meandering and uneven feeding; and FIG. 6 is a schematic diagram of a conventional color electrostatic recording apparatus. DESCRIPTION OF SYMBOLS 1...Recording medium, 5...Multi-needle electrode recording head, 7-1-0...Developer, 15a, 15
b...hole mark, 16a, 16b...
Mark detector, 17... Heater, 18...
...Hole mark former, 26...Heating circuit. Name of agent: Patent attorney Shigetaka Awano and one other person

Claims (1)

[Claims] A conveyance means for conveying a recording medium, a multi-needle electrode recording head disposed along a conveyance path of the recording medium so as to sequentially record images of different colors on the recording medium conveyed by the conveyance means, and a plurality of a developing device, a mark detection means for detecting hole marks provided near the multi-needle electrode head and along both side edges of the recording medium, and information obtained by the detection means. A correction means that calculates the amount of expansion/contraction and the amount of meandering in a direction perpendicular to the conveyance direction of the recording medium, and expands/contracts the multi-needle electrode recording head according to the calculated amount, and a correction means that shifts the recording start position of the image signal. A color electrostatic recording device characterized by comprising: