JPS61103171A - Multi-color image forming device - Google Patents

Abstract

PURPOSE:To form easily multi-color images at a high speed on the same transfer material by forming simultaneously plural colors of images on one drum, transferring simultaneously the image to the transfer material and executing such process by using plural pieces of rotary dielectric materials. CONSTITUTION:The electric charge pattern corresponding to the 1st and 2nd color signals is applied by a digital electrostatic charger 4A. The latent image of the 1st color is developed by a red toner of a negative polarity in a corresponding developing device 5A. The latent image of the 2nd color is developed by a positive black toner in a developing device 7A. The formed toner images are uniformly charged to the negative polarity by an electrostatic charger 8A before transfer as the above-mentioned drum 1A rotates. The charge of the polarity reversed from the toner is thereafter applied from the surface of the transfer material P by an electrostatic charger 9A before transfer and the toner image is transferred to the material P. The material P is in succession conveyed to the 2nd device B side and the 2nd latent image is formed by a digital electrostatic charger 4B to the surface of a solid dielectric drum 1B. The toner images of four colors; red, black, blue and green are thereafter fixed as the permanent images to the material P in the same manner and the transfer material is delivered.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention [Field of Industrial Application] The present invention relates to a multicolor image forming apparatus that forms multicolor images by electrostatic recording.

[Conventional technology]

In recent years, along with the speeding up of electronic computers, image output devices (V
As the colorization of TR, CRT, etc. is progressing, the demand for colorization of hard copies is increasing.

Although many color image forming apparatuses have been proposed in the past, they have not yet been commercialized due to numerous problems.

For example, as an example of what has been proposed so far, there is a full-power, large-type electrophotographic method disclosed in Japanese Unexamined Patent Publication No. 59-72870. The outline of this method is to use an f-theta lens to form an image-modulated laser beam as a spot light onto a charged photosensitive drum to form an electrostatic latent image, which is then developed, transferred, and fixed. be.

Therefore, in the case of color images, a transfer drum is installed in close proximity to the photosensitive drum, and the transfer material that is fed along the drum is subjected to the five steps of charging, exposure, development, transfer, and cleaning for each color, thereby overlapping the colors. The images are combined and transferred and then fixed.

[Problem that the invention seeks to solve]

Therefore, the time required for one copy is long, and the charger
The exposure device and developing device take up space, and the image forming device itself becomes large. For this reason, when attempting to form a multicolor image in three or four colors, there is a problem in that the time per copy becomes even longer.

The present invention aims to solve the problems of the conventional apparatus described above and provide an image forming apparatus capable of producing high-quality multicolor images.

Summary: Structure of the Invention [Means for Solving the Problems] The present invention includes a plurality of moving solid dielectric materials and a latent image that forms a latent image of a charge pattern in accordance with image information on each solid dielectric material. It has an image forming means, a developing means for forming a developed image of at least one color on the solid dielectric, and a transfer means for transferring the developed images on the plurality of solid dielectrics onto the same transfer material. It is characterized by:

[For production]

In the present invention, a latent image is formed on a first solid dielectric by a digital charger as a latent image forming means.

Developing this to form a toner image of at least one color and transferring the toner image onto a transfer material, while forming a toner image of another color on a second solid dielectric material by a similar process, The toner image is transferred onto the same transfer material to obtain a multicolor image.

〔Example〕

Hereinafter, details of the present invention will be explained with reference to embodiments shown in the drawings.

FIG. 1 is a schematic configuration diagram of a multicolor image forming apparatus according to the present invention, and FIG. 2 shows its process steps. R) - Form an image of a second color (for example, black B4fL) on the transfer material P,
The second device B forms a third color (for example, blue B) and a fourth color (for example, green G) on the same transfer material P by processes (V) to 01).

In Figure 1, IA-IB is a solid dielectric drum, 2A and 2B are cleaning devices, 3A and 3B are AC static eliminators, and 4A and 4
B is a digital charger (described later), 5A and 7A are developers for the first color (red R) and second color (black Bl) in the first device A, and 5B and 7B are developers for the third color (black Bl) in the second device B. Blue B)/fourth color (green G) developer, 8A/8B is pre-transfer charger, 9
A and 9B are transfer chargers, and l0A-10B are fixing devices.

First, processes (I) to (IV) for the first device A will be explained. After the surface of the solid dielectric drum 1A is cleaned by a cleaning device 2A, it is cleaned by an AC static eliminator 3A at approximately Ov.
Static electricity is removed up to

(I) Process The digital charger 4A charges the first and second
A charge pattern corresponding to a color signal is applied. In this case, the surface potential is +20 for the color signal of the first color (red R).
0v, the same 200V for the second color (black BJL),
The place where no signal is received is Ov.

(■) Process The first color latent image (-200V) is developed with a red toner of negative polarity using the corresponding developing device 5A. The developing method includes a two-component magnetic brush method and a non-contact developing method in which a developing sleeve 5Al is coated with a one-component insulating toner as shown in the figure. Special Publication 1986-3 as a contact development method
The one described in Japanese Patent No. 2375 can be applied. in this case,
The bias voltage applied to the developing sleeve is an alternating voltage, but the alternating current component allows the toner on the developing sleeve to form a powder cloud without contacting the toner on the solid dielectric, and the toner changes depending on the potential of the solid dielectric. A high frequency that can be transferred, for example, a frequency f of 2 to 3 KHz and a peak-to-peak value VPP of about 1.0 to 1.5 KV is preferable, and a DC component that is slightly lower than the background potential of the solid dielectric is preferable. It is preferable to apply a bias voltage superimposed with a high potential capable of preventing background fogging, for example, about 10 to 15 V. In this embodiment, non-magnetic toner is used.

Further, as another developing method, Japanese Patent Application Laid-Open No. 1999-110100 is used.

Those described in the No. 2 publication, etc. can also be applied.

(m) Process A second color latent image (-200V) is developed with positive black toner using the developing device 7A.

(IT) Process The two-color (for example, red and black) toner patches formed on the solid dielectric drum IA through the above process are uniformly charged to a negative polarity by the pre-rotation charger 8A as the drum IA rotates. The polarity of the entire toner is unified to negative polarity. Note that this pre-transfer charging may be of positive polarity.
``Then, the transfer charger 9A applies a charge of opposite polarity to the charged toner from the back side of the transfer material P that is sent in synchronization with the rotation of the drum IA, and the toner image is transferred onto the transfer material P.

The transfer material P is subsequently conveyed to the second device B, and during this time the toner image is fixed by the fixing device 10A. - Next, in the second device B, a third color (for example, blue B) and a fourth color (
For example, a charge pattern corresponding to a color signal of green (G) is applied to form the latent image shown in FIG. 2(V).

Thereafter, through the processes l) to ([) in the same manner as in the case of the first device iA, the four-color toner images of red, black, blue, and green are fixed as a permanent image on the transfer material P, and then transferred to the fixing device 10B. sent from.

The above embodiment uses the first and second devices to form a two-color image in each device to finally obtain a four-color image, but the number of devices, the number of colors in each device, etc. It can be increased as much as technically possible. - Also, as in the example, it is not just multicolor, but is usually done. By subtractive color mixing, it is also possible to obtain a full-color image by overlapping toners such as yellow, magenta, and cyan by performing image signal processing on the signals output to the digital chargers 4A and 4B.

FIG. 3 shows another embodiment of the transfer means, in which the toner image is pressure-transferred and fixed at the same time by pressure transfer rollers 9Al and 9Bl, and the charger 8A118B and transfer charger 9A-9B are not required. .

In the case of the corona transfer shown in FIG. 1, the charge due to corona discharge remains on the back surface of the transfer material P, and the toner charge remains on the surface of the transfer material P. It is preferable to provide a function to remove one residual charge.

On the other hand, in the case of pressure transfer and simultaneous fixing as shown in Fig. 3,
Although it is not particularly necessary, it is preferable to erase toner charges on the surface of the transfer material P using a corona static eliminator 11 or the like.

Applicable digital chargers 4A and 4B are known in Japanese Patent Application Laid-Open No. 54-78134, etc., but here, the basic principle of control necessary for the present invention will be explained based on FIGS. 4 and 5. I will briefly explain the following.

In FIG. 4, 1 is the solid dielectric material IA-1B, and 4 is digital chargers 4A and 4B. Figure 5 is 1 of Figure 4.
FIG. 3 is an enlarged cross-sectional view of a portion of a charge dot implantation element.

First, in FIG. 5, the digital charger 4 includes a first dielectric 20a such as ceramic glass, a drive electrode 15@control electrode 16, a screen electrode 17 having seven perchas 21 for ion emission, a control electrode 16 and a screen electrode 17. A second dielectric 20b is provided between the two. Between the drive electrode 15 and the control electrode 16,
An AC voltage is applied to the control electrode 16 and the screen electrode 17 from the DC power supply 23, and a DC voltage is applied between the screen electrode 17 and the conductive substrate 25 of the solid dielectric 1 from the DC power supply 24. is applied.

When a high-frequency alternating current voltage is applied between the drive electrode 15 and the control electrode 16, the electric field generated along the seven perchas 19 of the control electrode 16 causes the air to be destroyed by discharge and (◆) (-) ions are generated. Ions (=) spread to the seven perchas 19 of the control electrode 16.

Discharge caused by a creeping electric field near the drive electrode 15 can be prevented by covering the drive electrode 15 with a dielectric material.

The (+) and (-) ions generated in the aperture 19 of the control electrode 16 are applied to the surface of the solid dielectric 1 by the electric field acting in the direction of the solid dielectric 1.

The polarity of ions that can be applied onto the solid dielectric is determined by the power supply 23.
- Can be selectively changed by changing the polarity of 24.

In the present invention, for this purpose, the electric field between the screen electrode 17 and the control electrode 16 is controlled. In order to make the control simpler, the screen electrode 17
To illustrate a case where the voltage applied to the control electrode 16 is made variable while keeping the voltage constant, the screen electrode 1
7, with a constant voltage of -350V applied, the voltage applied to the control electrode 16 is -350V,! =
−750V (7), and the electric field generated between these two electrodes can be controlled by switching to two values. That is, for the dots to which (-) ions are applied (black in the first embodiment), the control electrode 16 is
When V is applied, a potential difference of 400 V is generated between the screen electrode 17 and the control electrode 16, so that the (-) ions in the aperture 19 are extracted, and the solid ? A is emitted to the dielectric and charges the dielectric surface. When -350V is applied to the control electrode 16, no potential difference is created between the two electrodes, so no ions are ejected.

When performing (+) ion charging, the absolute value of the DC voltage applied to the control electrode 16 and screen electrode 17 is the same as (-) ion charging, and the control electrode 1
6 and the screen electrode 17 may be reversed in polarity.

With a charger configured like this, the charge per inch can be
When obtaining 5 images with a resolution of 240 dots, A4
The number of dots needed to cover the width of the printing paper is 2048 dots.

In order to reduce the switching of these 2048 control electrodes 16, as shown in FIG.
16-3 are formed into a matrix, and while the drive line is switched synchronously by the multiplexer 26 as the solid dielectric 1 rotates (sub-scanning), control lines 16-1 to 16-3 are connected to the points where dots need to be applied. In the case of control of 2048 dots, which performs on-off of 3 and forms a latent image, the i6 drive line and 1
This is done by controlling 28 control lines.

In the matrix of FIG. 4, when a high frequency AC voltage is simultaneously applied to the drive electrode 15 from the power source 22 and a DC voltage from the power source 23 is applied to the control electrode 16, ions are emitted from the aperture 19 at the intersection thereof. power supply 23
The DC voltage from the multiplexer 27 is selectively applied to the control electrodes 16-1-16-3.

In the matrix of FIG. 4, nine elements (drive line 3) x (control line 3) are illustrated for simplification. The drive line 15 is arranged substantially perpendicular to the rotation direction of the solid dielectric drum l, and the multiplexer 2
6, the high frequency AC voltage is applied to the drive line 15-1-
15-3, they are switched synchronously one after another in accordance with the circumferential speed of the solid dielectric drum (1).

Figure 6 corresponds to the color signals of the first and second colors (÷)
(A) in Figure 0 is a timing chart of the voltages applied to each electrode of the digital charger in order to simultaneously apply a (-) charge pattern to the solid dielectric l by the digital charger in Figure 4. The horizontal axes of (b), (c), and (d) are
The time is the N1 axis.

(a) is the high frequency AC voltage v applied to the drive electrode 15
1 waveform, and the peak-to-peak value VPP is 2K.
It is V. to is the period of this waveform. Due to this (1), the control electrode 16 is placed near the 7 perch 19 (+
)(-) ions are generated.

(b) and (c) are color signal voltages applied to the control electrode 16, respectively. (b) is the color signal of the first color 4, and (c) is the color signal of the second color. This color signal voltage has a pulse-like waveform, and each pulse width is t2・t
It is 3. The pulse voltage is -P 750V and -750V
It is V.

(d) shows the AC rectangular wave voltage v4 applied to the screen electrode 17, and the peak-to-peak value VPP is 7.
00V, and the period is t4.

As described in the explanation of FIG. 4, the high frequency AC voltage v1 applied to the drive electrode 15 is turned on and off by the multiplexer 26 to turn on the drive electrodes 15-1 to 15-3 one after another.
Turning off, that is, drive electrodes 1 and 5-1
After turning on the drive electrode 15-2 for a certain period of time, turning it off and then turning it off again for a certain period of time, turning on the drive electrode 15-2 for a certain period of time, turning it off, and performing the same operation on the drive electrode 15-3. ON to return to 15-1
・Continues OFF switching operation. - On the other hand, an AC rectangular wave voltage v4 is always applied to the screen electrode 17 in an ON state.

As shown in FIG. 7, the time during which one drive electrode is ON is at least one period of the AC rectangular wave voltage V4 applied to the screen electrode 17, that is, t4.

For example, when the drive electrode 15-1 is ON, the control electrode te-t (b) is connected to the control electrode 16-1.
2 (c), when the color signal voltage is sent at the timing shown in FIG. From aperture (-)
Ions are applied onto the solid dielectric material l at the same time, and no ions are applied from the control electrode 16-3.
Similarly, regarding the drive electrode 15-2, an image signal input from an external device is sent to the control electrode, and a charge is applied to the dielectric.

In this way, each (10) (-) ion is applied from the seven vertices 19 of the control electrode 16 onto the solid dielectric l according to the basic principle explained in FIG.

Incidentally, the third color and the fourth color may be considered in the same manner.

Note that it is impossible to measure the surface potential of a charge pattern formed on a solid dielectric material for each dot of the pattern due to resolution problems of an electrometer probe. Therefore, the potential measured by the electrometer is the average value of the charge pattern of the latent image. When the charges of all dot patterns are applied to an area wider than the resolving power of the probe, the potential becomes about ±200V, and when there is no charge of the dot patterns, it becomes about Ov.

C. Effect of invention
1. Unlike conventional color electrophotographic devices, the present invention simultaneously forms multiple color images on one drum, transfers them to a transfer material all at once, and performs this process using multiple rotating dielectrics. Therefore, multicolor images can be easily formed on the same transfer material at high speed.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the configuration of the apparatus of the present invention, FIG. 2 is a state diagram of the surface potential Vs on a solid dielectric and a toner image based on the present invention, and FIG. 3 is another embodiment of the present invention. Figure 4 is a schematic diagram of the J5 Ming digital charger, Figure 5 is an enlarged cross-sectional view of a part of it, and Figure 6 is the timing and timing chart of the voltage applied to each electrode of the digital charger. figure. 1-IA-IB is a solid dielectric, 4-4A-4B is a digital charger, 5A-7A, 5B, and 7B are developing devices, and P is a transfer material. Figure 5 Figure 2 Figure 6

Claims (1)

[Claims] (1) A plurality of moving solid dielectrics, a latent image forming means for forming a latent image of a charge pattern according to image information on each of the solid dielectrics, and at least one latent image forming means on each of the solid dielectrics;
A multicolor image forming apparatus comprising a developing means for forming a developed image of more than one color, and a transferring means for transferring the developed images on the plurality of solid dielectric materials to the same transfer material.