JPH01196082A - Multicolor image forming device - Google Patents

Abstract

PURPOSE:To take a color hard copy of image data while maintaining high picture quality by repeating latent image formation and development according to color signals generated by a printer part in predetermined order. CONSTITUTION:An input image is passed through an interface 21 and stored in prescribed areas MR, MG, and MB of an image memory 22 according to its color components R, G, and B. Image data of a specific color is selected and outputted from the image memory 22 to the printer part 23. The image memory 22 selects corresponding areas according to the color signals and transfers the image data from the areas to the printer part 23. Consequently, images data which are inputted in various types of order are visualized in invariably preferable order and a hard copy of high picture quality is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multicolor image forming apparatus that forms a multicolor image using toner based on transferred image data.

[Prior Art] A multicolor image forming apparatus as described above includes a data input section that is involved in transferring image data, and a printer section that is involved in forming toner images. First, I will explain the printer section.

Image formation by electrophotography involves (1) uniformly charging an image carrier having a photoconductive layer on a conductive substrate, (2) forming a latent image by image exposure, and (3) exposing the latent image to toner. Develop (
The process includes steps of 4) transferring the formed toner image to a transfer material, (5) fixing the toner image to the transfer material, and (6) cleaning the image carrier. The formation of a polychromatic image is described above (
A method (multiple transfer method) in which the steps up to 4) and (6) are performed multiple times to form a multicolor toner image by overlapping toner images on the same transfer material and fixing the image, or (3) above. A method in which the above steps are repeated multiple times to form a multicolor toner image on the image carrier, and then the toner image is transferred to a transfer material and fixed.
For example, Japanese patent application No. 58-184381 (one-time answer method)
It has been known. For the latter application, an image carrier with a transparent insulating layer provided on the outside of the photoconductive layer (
1) --order charging, (2) secondary charge simultaneous image exposure, (3) --order exposure, (4) a method in which development is performed in one cycle, or (1)
)-secondary charging, (2) secondary charging, (3) image exposure, and (4) development in one cycle.

As the image exposure means, one that can be controlled by electrical signals, such as a laser or an LEDS liquid crystal shutter, is used. Such an image exposure means can form a latent image on the image carrier with high density, and as a result, a high quality image can be obtained. In the one-time response method, the image bearing member on which the toner image is formed is uniformly charged, but at this time, it is preferable to use a reversal phenomenon so that the charge polarity of the toner is not reversed. Therefore, transfer efficiency can be maintained.

[Problem to be solved by the invention]

With the one-time response method described above, the device configuration can be simplified and the positions of each color image can be aligned with high precision.
The image quality changes greatly depending on the order in which the images are created. Furthermore, even in the multiple transfer method, the color and character reproducibility change depending on the order in which the colors are layered. That is, in a multicolor printer, the vertical relationship of color toner images on a transfer material changes depending on the order of image formation, and therefore the reproduced colors differ. In addition, in the one-turn response method, a latent image is formed on the toner image portion on the image carrier by image exposure light, so the contrast of the latent image becomes small due to the light transmittance of the toner and the amount of charge of the toner. When reversal development is employed, the amount of toner of the color to be overlaid later tends to be small.

Furthermore, the one-time answer method has the following problems. FIG. 3 is a diagram showing a cross section of an image carrier on which a toner image is formed. (a) is immediately after being uniformly charged, and the surface potential is uniform. Next, the area around this toner-attached area is exposed by image exposure, and the case where the toner-attached area is not exposed is a peak). At this time, the surface potential of the image carrier is high at the toner-attached portion and low at the periphery.

In this case, since the toner charge polarity is the same as the surface potential of the image carrier, an electrostatic force acts on the toner in the direction of the arrow in the figure. As the toner in the upper layer of the toner layer has a weak force that binds it to that position, as shown in the direction of the arrow,
Toner is scattered around the image. This causes image blurring, which is a major factor in deteriorating image quality. Such development is unavoidable in the one-time response method.

On the other hand, in relation to image data input, there are the following problems. When image data is transferred one color at a time in plane sequence, for example, if red (R), green (G), and blue (B) are transferred in the order, the printer section will respond accordingly, for example, by printing their complementary colors. Latent image formation and development must be performed in the order of cyan (C), magenta (M), and yellow (Y).

However, according to this order, the printer section may only be able to form images with insufficient color reproducibility for the reasons described above.

Conventionally, images have been created according to the order in which the image data is transferred without considering the characteristics of the printer, but depending on the order in which the colors are transferred, image blurring, color reproducibility, character reproducibility, etc. can be extremely undesirable. Met.

An object of the present invention is to provide a multicolor image forming apparatus that can make color hard copies of image data while maintaining high image quality.

[Means to solve the problem]

To this end, the multicolor image forming apparatus of the present invention includes a data input unit that sequentially inputs image data of different colors and stores the data in different areas of the image memory for each color, and a signal that is sent to the image memory when the image data is sent to the image memory. a printer section that forms a latent image on the image carrier according to the image data transferred from the specific area of the image memory by the above, and develops the latent image with a toner of a color corresponding to the color signal; The printer section repeats the latent image formation and development steps in response to color signals generated in a predetermined order.

[Effect]

In the present invention, in order to form images while maintaining optimal image formation as a printer, regardless of the order in which image data is transferred, the following steps are taken.

(2) Provide an image memory in which areas corresponding to the colors of the printer's image data are set.

■The data input section inputs image data input from the outside.
Each color is stored in the corresponding area i of the image memory.

(2) Color signals specifying a specific color are input to the data input section and the printer section in a predetermined order.

(2) The data input section outputs image data from the image memory area corresponding to the color signal.

(2) The printer section forms a toner image of a color corresponding to the input color signal.

(2) The two-color signal is switched, and the steps (2) to (4) are performed again to form a toner image of another color. Repeat this from now on.

The above-mentioned image blurring that occurs in single-rotation type printers is often seen when, for example, the background of characters is colored in a different color.

Such image blurring is noticeable in colors to which visual sensitivity is high, and according to the inventor's study, it is most noticeable in the order of black, cyan, magenta, and yellow.

For this reason, the single-rotation type color printer uses colors in the order of inconspicuousness, that is, yellow, magenta, cyan,
It is preferable to form images in the order of black.

When using a long-wavelength image exposure source such as a semiconductor laser, the toner that adheres to the image carrier is one that allows light to easily pass through. is also preferable.

〔Example〕

In the following embodiments, an example in which the printer section is of a one-rotation type will be described.

FIG. 4 is a diagram showing the configuration of the printer section.

In the figure, 1 is an image carrier on a drum that has a photoconductive layer such as OPC or Se and rotates in the direction of the arrow, and 2 is an image carrier 1.
3 is an image exposure device, 4Y,
4M, 4C, and 48 are developing devices that store yellow, magenta, cyan, and black toners; 5 is a transfer pole that corona-transfers the toner image on the image carrier 1 onto the transfer material P; and 6 is a toner and a pre-transfer exposure lamp for eliminating static electricity on the surface of the image carrier; 7 a separation pole for separating the transfer material P from the image carrier; 8;
is a fixing device that fixes the toner image transferred to the transfer material P;
Reference numeral 9.10 indicates a lamp and corona discharger for static elimination before cleaning, and reference numeral 11 indicates a cleaning device for cleaning the image bearing member.

Figure 5 shows the image exposure device (
FIG. 2 is a diagram showing a laser beam scanner. A laser beam emitted from a laser diode 12 that blinks at high speed according to image data is incident on a polygon mirror 13 that is rotated by a drive motor. After being reflected by the mirror surface, the laser beam passes through an f-theta lens 14 and a cylindrical lens 15 to scan the image carrier 1.

16 is an indexer for detecting the beam scanning position, 17 is a collimating lens, 18 is a cylindrical lens, and 19 is a reflecting mirror. Laser lighting time is 1
This allows pixels to be set to three different lengths.

The image forming types of the printer section are Y (yellow), 9M (magenta), C (cyan), and BK (black).

FIG. 1 is a block diagram of a multicolor image forming apparatus according to this embodiment. Examples of image input means include a monitor TV, video deck, video camera, video floppy, and image scanner. It is assumed that the image data input from these are separated into colors such as R, G, and B.

The input image data is stored in predetermined areas MR, MG, and MB of the image memory 22 according to its color components R, G, and B via the interface 21, respectively. Image data of a specific color is selected from this image memory 22 and output to the printer section 23 . The control section 24 generates color signals as control signals in the order in which the printer section 23 described in FIG. 4 forms images. The image memory 22 selects a corresponding area according to the color signal, and transfers the image data from there to the printer section 23.

The order of the color signals generated by the control unit 24 is Y→M→C according to the image forming order of the printer unit 23, so the first color signal Y
is generated, the area MB of the image memory 22 in which the complementary color data (B component) is stored is selected, and the image data is transferred to the latent image forming means (corresponding to the image exposure device 3) 23A of the printer section 23. will be forwarded to. The latent image forming means 23A forms a Y component latent image on the image carrier based on the inputted B component image data. The electrophotographic section 23B serving as a developing means develops it with yellow toner. Thereafter, the M component and C component images are sequentially formed in the same manner.

In this way, the order of the color components of the image data transferred to the printer section 23 is constant regardless of the order in which they are input from the outside, and the above-mentioned operations are performed in the printer section 23 without being changed. A high quality multicolor toner image is formed. For this reason, it is desirable that the control section 24 be built into the printer section 23, but the present invention is not limited to such a configuration.

The above-mentioned operation can be generalized without being limited to image input means by using B data as image data to be developed with Y toner. In addition, in FIG. 1, black data is handled, so the black toner in the printer section 23 is not used, but the input data R, G, and B are input to a color correction circuit (not shown) and the black data is processed there. Once created and stored in the image memory, the above processing is the same even when a black (BK) component is added as the recording color.

Developing device and developing method in the multicolor printer shown in FIG.
Regarding the developer and other processes, please refer to Japanese Patent Application Laid-open No. 59-181362 and No. 22284 filed earlier by the applicant.
7, 222851, 222852, 222853
, Japanese Patent Application No. 60-192172 and the like are preferred.

The process of forming a multicolor image used in the above printer will be explained based on FIG. 2.

In FIG. 2, the image carrier has a photoconductive layer on a conductive substrate, and the latent image forming means includes a charger that uniformly charges the image carrier and a light beam such as a laser that irradiates the image carrier. It consists of a combination with an image exposure device.

FIG. 2 shows the change in surface potential of the image carrier, where PH is the exposed portion of the image carrier, DA is the unexposed portion of the image carrier, T1 is the first developed toner,
T2 indicates the toner developed for the second time, and DUP indicates the potential increased in the exposed portion of the image carrier during the first development. For the following explanation, the polarity of the latent image is assumed to be positive.

■The image carrier is uniformly charged with a charger and the surface potential is E.
becomes.

■The image exposure device performs image exposure for the first color, and the exposed area PH
The potential of decreases depending on the amount of light irradiated. In this way, an electrostatic latent image is formed.

(2) The latent layer is developed using a developing device that applies a positive bias approximately equal to the surface potential of the unexposed area DA. As a result,
Portion PH where positively charged toner T1 has a relatively low potential
The first color toner image is formed. Note that in the area to which the toner T1 has adhered, the potential increases by DUP due to the charge of the adhered toner, but normally does not reach the surface potential E of the unexposed area DA.

(2) The image carrier is uniformly charged by a charger with the toner image attached thereto, and the surface potential of the image carrier becomes E regardless of the presence or absence of toner T1.

, (2) Image exposure of the second color is performed by the image exposure device, and the potential of the exposed portion PH decreases in accordance with the amount of irradiated light. In this way, an electrostatic latent image is formed. When the area to which the toner has adhered during the first color development is exposed again, the potential becomes approximately equal to the potential after development.

Develop with toner T2 of a different color from the first color toner in the same manner as in (2) and (2). As a result, a two-color toner image is obtained on the image carrier.

Thereafter, the same process is repeated a necessary number of times to obtain a multicolor toner image on the image carrier.

Multicolor printers using this process do not require a means to repeatedly convey the transfer material to the transfer position, and there are fewer parts driven by motors and other parts, so the configuration is simple and compact, and it is easy to precisely align each color image. It is.

〔Effect of the invention〕

By using the multicolor image forming apparatus configured as described above, it is possible to realize a hard copy system in which the dependence between the image data input section and the printer section is minimized. That is, image data input in various orders is always visualized in a preferred order, and a high-quality hard copy can be formed. Furthermore, the system can be configured without being particularly conscious of the relationship between the input speed of image data and the speed of the printer unit.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a multicolor image forming apparatus according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the process of forming a multicolor image, and FIG.
In Figure [a], the mountain is a cross-sectional view of the image carrier on which the toner image is formed, Figure 4 is a cross-sectional view of the printer section, and Figure 5 is the image exposure device (laser beam scanner) used in the printer shown in Figure 4. ) is an explanatory diagram. Agent Patent Attorney Tsuneaki Nagao Figure 3 Figure 4

Claims (4)

[Claims] (1) A data input section that sequentially inputs image data of different colors and stores the data in different areas of the image memory for each color; a printer section that forms a latent image on the image carrier according to the image data transferred from the printer and develops the latent image with toner of a color corresponding to the color signal, and the printer section A multicolor image forming apparatus characterized in that the steps of forming a latent image and developing are repeated in accordance with color signals generated in sequence. (2) The multicolor image forming apparatus according to claim 1, wherein the printer unit sequentially forms a multicolor toner image on the image carrier through the steps described above. (3) The multicolor image forming apparatus according to claim 2, wherein the printer section develops yellow, magenta, cyan, and black in this order. (4) The printer section includes a step of transferring to a transfer material after the development step, and sequentially forms a multicolor toner image on the transfer material. multicolor image forming device.