JPH0377992B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an apparatus for developing an electrostatic latent image formed on an electrostatic recording medium with liquid toner, and in particular, it relates to an apparatus for developing an electrostatic latent image formed on an electrostatic recording medium with liquid toner, and in particular, it involves reciprocating the recording medium and developing different colors. The present invention relates to a color electrostatic recording device that obtains a color image by superimposing recorded images.

BACKGROUND OF THE INVENTION In recent years, hard copy devices such as printers and plotters have been actively converted to color. Among them, color electrostatic recording devices using a liquid toner development method can record large screens such as A1 size and A0 size at high speed, so they are a promising method and various improvements have been made.

A conventional color electrostatic recording device will be explained below.

FIG. 1 is a schematic diagram of a conventional color electrostatic recording apparatus. 1 is an electrostatic recording head, 2 is an electrostatic recording paper, 3a, 3b, 3c, and 3d are developing units each supplied with liquid toner of a different color that moves up and down independently; 4 is a recording head 1 and the electrostatic recording paper. 2 is a pressing roller for maintaining close contact; 5 is a conveyance roller; 6 is a registration mark detector consisting of a photo sensor; and 7 is a registration mark. The operation of the color electrostatic recording apparatus configured as described above will be explained.

First, before recording an image, registration marks are placed at regular intervals K lines on the left and right positions outside the effective screen of the electrostatic recording paper 2 using the recording head 1 and the developing device 3a supplied with black liquid toner. 7 is formed and developed. At this time, the electrostatic recording paper 2 is conveyed by the conveyance roller 5 in the direction shown by arrow A in the figure. When the recording of the registration mark 7 is completed, the conveyance roller 5
is reversed, the electrostatic recording paper 2 is moved in the direction shown by arrow B in the figure, and then pulled back to its original position.

Next, the developing device 3b supplied with the liquid toner of the first color (for example, cyan) is raised to the developing position, and the electrostatic recording paper 2 is conveyed in the direction of arrow A in the figure to form an image of the first color. Record. During this recording, the registration marks 7 are sequentially detected by the registration mark detectors 6 provided on the left and right sides, and the transport roller 5 is fed so that pixels corresponding to the K line are always recorded between the registration marks 7. The amount and timing of applying the recording voltage to the recording head 1 are controlled.

When recording with the first color is completed, the conveyance roller 5 is reversed again, conveyed in the direction of arrow B in the figure, and pulled back to the original position.

Next, the developing device 3c supplied with the liquid toner of the second color (for example, magenta) is raised to the developing position, and the image of the second color is recorded over the image of the first color. In this case, as in the case of recording the first color, the electrostatic recording paper 2 is moved by the conveyance roller 5 to the arrow A in the figure.
While conveying in the direction shown, the registration mark detector 6 sequentially detects the registration marks 7, and the feed amount of the conveyance roller 5 and the recording head 1 are adjusted so that the registration marks 7 are always recorded with pixels corresponding to the K line. The timing of applying the recording voltage to is controlled. By doing so, it is possible to accurately align the first color and the second color.

When the recording of the second color is completed, the conveyance roller 5 is reversed again and the electrostatic recording paper 2 is pulled back to its original position. A color image is obtained by performing this operation for a third color (for example, yellow) and black.

Problems to be Solved by the Invention However, with the above conventional configuration, the electrostatic recording paper is moved back and forth five times, and the tension applied to the electrostatic recording paper during transportation causes the electrostatic recording paper to stretch and make it difficult to produce accurate colors. There have been problems such as the inability to overlap, wrinkles on the electrostatic recording paper, and staining of the electrostatic recording paper by the conveyance roller. Therefore, when recording registration marks, a device that also records black color at the same time, or a device that records black color at the same time, or three black developers are used.
Proposals have been made for devices that perform color mixing, but
Even so, there was a drawback that the electrostatic recording paper had to be transported at least three times back and forth.

In order to solve this problem, a color electrostatic recording device having the configuration as shown in FIG. 2 was devised.
0a to 10d are arranged to perform recording in any case where the electrostatic recording paper 9 is reciprocated. It is true that in the case of a recording apparatus having such a configuration, the number of times the electrostatic recording paper 9 is moved back and forth can be reduced compared to the recording apparatus shown in FIG. However, the amount of movement of the electrostatic recording paper during the recording operation is still large, resulting in the problem that the electrostatic recording paper stretches, wrinkles, etc. occur. The color electrostatic recording device shown in Figure 2 was developed in Japanese Patent Application Laid-Open No. 59-37556.
It is also proposed in the Publication No.

The present invention has been made in view of the above problems, and reduces the number of reciprocations and the amount of movement of the recording medium during recording operations, thereby preventing stretching and wrinkles of the recording medium and producing good color images. The object of the present invention is to provide a color electrostatic recording device that obtains a color electrostatic recording device.

Means for Solving the Problems In order to achieve the above object, the present invention includes a conveyance means for conveying a recording medium in both forward and reverse directions along a predetermined conveyance path, and a conveyance means provided in the conveyance path of the recording medium for recording the recording medium. A recording head forms a latent image corresponding to a recorded image on a medium, and three recording heads are arranged along the conveyance path on the recording medium ejection side and one on the recording medium supply side of the recording head. 4 latent images formed on the recording medium, respectively.
Four developing devices that visualize images in different colors, and when the recording medium is conveyed in the forward direction, recording signals corresponding to the latent images are sent to the recording head in order from the front edge of the recorded image. a recording control means for outputting a recording signal corresponding to the latent image to the recording head in order from the rear end of the recorded image when the recording medium is conveyed in the reverse direction; The recording medium is conveyed in the forward direction, and recording is performed using a developing device located on the recording medium ejection side of the recording head and located closest to the recording head, and then,
The recording medium is conveyed in the opposite direction and recorded using a developing device located on the recording medium supply side of the recording head, and then the remaining developing devices located on the recording medium ejection side of the recording head are used to convey the recording medium in the correct direction. The images are recorded in the order in which they are arranged in the transport direction.

Effects With the above configuration, the present invention can reduce the number of times the recording medium is moved back and forth, and also reduce the amount of movement of the recording medium. As a result, the stretching and wrinkles of the recording medium due to the movement of the recording medium can be reduced. It is possible to reduce the occurrence of dirt, stains, etc., and it is possible to obtain clear color images through accurate color superposition.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a perspective view of essential parts of a color electrostatic recording apparatus showing an embodiment of the present invention.

In FIG. 3, 30 is an electrostatic recording head, 32 is electrostatic recording paper, 34a, 34b, 34c, and 34d are developing units each supplied with liquid toner of a different color that moves up and down independently, and 31 is electrostatic recording paper. 32 is a holding roller for maintaining close contact with the recording head 30; 33 is a conveyance roller; 35a and 35b are registration mark detectors each consisting of a photo sensor having a light emitting part and a light receiving part; 21 is a registration mark. Here, the configuration differs from the conventional recording apparatus in that one developing device is provided on the side where the electrostatic recording paper 32 of the recording head 30 is extended, and three developing devices are provided on the discharge side.

Developing device 34 to which black toner is initially supplied
A is raised to the development position, and the registration mark 36 and a black image are recorded and developed. Next, the developing device 34b supplied with the liquid toner of the second color is raised to the developing position, and an image is recorded and developed while the electrostatic recording paper 16 is pulled back. At this time, the recording signals applied to the recording head 30 are output in order from the rear end of the image.

After recording the second color image, the third color image is formed while the electrostatic recording paper 32 is taken out again. To record the fourth and final color, the ejected electrostatic recording paper 32 is once returned to the recording position, recording and development is performed from the leading edge of the image, and when recording is completed, the recording paper is ejected and image formation is completed. .

FIG. 4 shows a block diagram of a control circuit for the color electrostatic recording apparatus of the present invention shown in FIG.

In FIG. 4, when an operation start signal is given to the sequence control circuit 26, the electrostatic recording paper 3
The operation of recording a registration mark 36, a recording start mark (not shown), and a black image thereon is started. That is, a control signal is sent from the sequence control circuit 26 to the developer control circuit 27 and the pump control circuit 28, the control circuit 24a operates the motor 18a, and the developer 34a is set at the developing position.

After the developing device 34a is set, a control signal is then applied from the sequence control circuit 26 to the motor drive circuit 23. This signal causes the electrostatic recording paper 32 to
is pulled out in the direction shown in FIG. 3E. Simultaneously with this movement of the electrostatic recording paper 32, the sequence control circuit 2
6 sends an image signal to the recording driver circuit 21 for forming a black image recording start mark, a registration mark 36, and a recording end mark (not shown). The registration marks 36 are recorded every K lines on the left and right sides outside the effective screen.

Next, in response to a signal from the sequence control circuit 26, the developing unit 34a is lowered and replaced by the driving circuit 24.
b is activated and the developing device 34b is set at the developing position. On the other hand, the conveyance roller 33 is connected to the motor drive circuit 2.
2 to rewind the electrostatic recording paper 32 in the direction shown in FIG. 3F.

During this rewinding, the first electrostatic recording paper 3
2. The recording end mark, registration mark 36, and recording start mark recorded at the time of extraction are detected by the recording start mark detector 35b and the registration mark detector 20a, respectively, and after being amplified by the amplifier circuit 25, they are sent to the sequence control circuit. The recording start timing and the recording timing of each line are determined. That is, recording is started after a predetermined time (or number of lines) has elapsed since the recording end mark recorded for the first time is detected by the recording start mark detector 35b.
Further, the registration mark detector 20a detects the distance between the registration marks 36, and controls the image signal sent from the sequence control circuit 26 to the recording driver circuit 21 so that images for K lines are always recorded at this interval.

After the recording of all images is completed and the recording start mark recorded during the first mark recording is detected by the recording start mark detector 35b, the electrostatic recording paper 32 is rewound until the development of all latent images is completed. to finish recording the second color.

Next, the developing device 34c is set at the developing position, the electrostatic recording paper 32 is moved in the direction shown by E in FIG.
The third color image is recorded using the same control as that for color.

The same control is performed for the fourth color to obtain a color image. Here, in order to explain the present invention in more detail, the amount of movement of the recording medium during the recording operation will be explained using FIGS. 2 and 5.

FIG. 2 is a side view of the arrangement of a conventional color electrostatic recording device.
10b, 10c, and 10d are used for recording and development in this order. When the recording length is L, the electrostatic recording paper 9 is extended by (L+1 ₁ ) to complete the recording and development of the first color (for example, black). Recording and development of the second color (for example, cyan) may be performed when the electrostatic recording paper 9 is pulled back, and the electrostatic recording paper 9 may be moved by (1 ₁ +L+1 ₁ ). Next, apply the electrostatic recording paper 9 again (1 ₁ L + 1 ₁ + 1 ₂ )
Move and record a third color (for example, magenta),
Perform development. For recording and developing the fourth color (for example, yellow), use the electrostatic recording paper 9 (1 ₁ + 1 ₂ + L + 1 ₁ +
1 ₂ ). Finally, the electrostatic recording paper 9 is ejected by (1 ₂ +1 ₁ +1 ₁ +1 ₂ +1 ₃ +L) to complete the entire operation.

Therefore, the total amount of movement of the electrostatic recording paper 9 is (5L+91 ₁
+51 ₂ +1 ₃ ). If 1=1 ₁ = 1 ₂ = 1 ₃ , then in the case of the conventional configuration, the total amount of movement is (5L+151).

On the other hand, the amount of movement of the electrostatic recording paper during the recording operation of the color electrostatic recording apparatus of the present invention will be explained with reference to FIG.

recording a first color image using the developer 34a;
When developing, take out the electrostatic recording paper 32 by (L+1 ₁ ) and record a second color image using the developing unit 34b. When developing, take out the electrostatic recording paper 32 by (1 ₁ , L+1 ₁ ) and record the image from the rear edge. When recording and developing an image of the third color using the developing device 34c, the electrostatic recording paper 32 is pulled out by (1 ₁ +L+1 ₁ +1 ₂ ). Developing device 34d
When recording and developing a _{fourth color} image using Recording paper 32 (L+1 ₁ +1 ₂ +
1 ₂ ) Move to form an image. Finally, ₁₃ pieces of electrostatic recording paper 16 are ejected to end the recording.

Therefore, the total transfer amount of the electrostatic recording paper 32 is (5L + 71 ₁ +
41 ₂ + 1 ₃ ). If 1 = 1 ₁ = 1 ₂ = 1 ₃ , the total amount of movement will be (5L + 121).

As described above, in the conventional recording apparatus, the total movement distance of the electrostatic recording paper is (5L+151), but in the recording apparatus according to the present invention, it is (5L+121). Therefore, stretching and wrinkling of the recording medium can be reduced accordingly, and the overall recording time can also be shortened.

Effects of the Invention As is clear from the above description, according to the present invention, three developing devices of different colors are provided on the recording medium discharge side of the recording head, and one developing device is provided on the recording medium supply side of the recording head. is conveyed in the forward direction to be located on the recording medium ejection side of the recording head, and
Recording is performed with the developing device located closest to the recording head, then the recording medium is conveyed in the opposite direction and recording is performed with the developing device located on the recording medium supply side of the recording head, and then the recording medium is Since the remaining developing devices located on the recording medium ejection side of the head are arranged in the order in which they are arranged in the positive conveyance direction of the recording medium, it is possible to reduce the number of times the recording medium is moved back and forth, and the amount of movement of the recording medium is also reduced. As a result, stretching of the recording medium, occurrence of wrinkles, staining, etc. due to movement of the recording medium can be reduced, and clear color images can be obtained by accurate color superposition.

Furthermore, the recording time can be reduced compared to conventional devices.

[Brief explanation of drawings]

FIG. 1 is a perspective view of essential parts of a conventional color electrostatic recording device, FIG. 2 is a side view of the arrangement of a conventional color electrostatic recording device, and FIG. 3 is a color electrostatic recording device according to an embodiment of the present invention. 4 is a block diagram of the control circuit of FIG. 3, and FIG. 5 is a side view of the arrangement of a color electrostatic recording apparatus in an embodiment of the present invention. 30... Electrostatic recording head, 32... Electrostatic recording paper, 33... Conveyance roller, 34a, 34b, 34
c, 34d...Developer, 35b...Registration mark detector.

Claims (1)

[Claims] 1. A conveyance means for conveying a recording medium in both forward and reverse directions along a predetermined conveyance path; a recording head provided in the conveyance path of the recording medium and forming a latent image corresponding to a recorded image on the recording medium; Three of them are arranged on the recording medium ejection side and one on the recording medium supply side of the recording head along the conveyance path, and the latent images formed on the recording medium by the recording head are colored in four different colors. When the recording medium is conveyed in the forward direction, recording signals corresponding to the latent image are sequentially outputted to the recording head from the front end of the recorded image, and and recording control means for outputting recording signals corresponding to the latent image to the recording head in order from the rear end of the recording image when the recording medium is conveyed in the reverse direction,
First, the recording medium is conveyed in the forward direction, and a developing device located on the recording medium ejection side of the recording head and closest to the recording head performs recording, and then the recording medium is The developing device located on the recording medium supply side of the recording head performs recording by conveying in the opposite direction, and then the remaining developing devices located on the recording medium ejection side of the recording head are moved in the positive conveyance direction of the recording medium. A color electrostatic recording device characterized by recording in the order of arrangement.