JPH01200976A - Electrophotographic color printer - Google Patents

Abstract

PURPOSE:To miniaturize extremely an exposure means, by establishing the exposure means wherein a plurality of long narrow strip areas corresponding to in a pair plurality of photographic printing lines continuing on a paper are established on a sensitizing belt, and light corresponding to photographic printing information of each color is directed onto each long narrow strip area to record said photographic printing information as an latent image. CONSTITUTION:A sensitizing belt 10 is travelled in a direction normal to a paper and besides, light corresponding to photographic printing information of each color is directed onto each long narrow strip area of the travelling sensitizing belt 10 by an exposure means 30 corresponding to a width of the sensitizing belt 10. Thereby, an electrostatic latent image corresponding to photographic printing information of each color is formed on each long narrow strip area. Then, pigment of each color is adhered onto each long narrow strip area of the sensitizing belt 10 on which the latent image is formed by a developing means 32, and the latent image of each color is made visible. Thereafter, the sensitizing belt 10 is stopped at a certain position to the paper by a belt activation stop control means 22. A visible image of each color which is made visible on each long narrow strip area of the sensitizing belt 10 stopped at the certain position is photographically printed on each photographic printing line corresponding to the paper by a transfer means 36 under this state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic color printer that performs color printing using an electrophotographic method.

[Prior Art] In the electrophotographic recording method, recorded information is recorded as an electrostatic latent image on a photoreceptor, and a pigment such as toner (developer) is attached to this latent image to form a visible image (developed image). This method of transferring visible images onto paper is generally used in copying machines, but in recent years this electrophotographic method has also been adopted in printers.

As shown in FIG. 3, a conventional electrophotographic printer has a photoconductive material 100 on the surface of a conductive cylindrical substrate 100a.
The structure used a photosensitive drum 100 coated with b.

During printing, the photosensitive drum 100 is rotated and the charger 10
2, the surface of the photosensitive drum 100 is negatively charged, and then the exposure means 104 such as an LED array is used to irradiate light according to the print information to cause the light-aligned portion to lose its charge. A developing device 106 applies positively charged toner to the surface of the photosensitive drum 100 to visualize the latent image, and a transfer device 108 electrostatically transfers the toner image onto a sheet of paper 110. The image is transferred and then fixed in a fixing device 112.

114 is a static elimination lamp, and 116 is a cleaner.

These electrophotographic printers have excellent features such as being able to easily increase the number of printed dots and obtain high print quality, high speed printing, printing on plain paper, and low noise. There is.

[Problems to be Solved by the Invention] However, the conventional electrophotographic printer using a photosensitive drum as described above has the following drawbacks.

First, the equipment is expensive. In particular, when a laser beam method is used as an exposure means to irradiate a charged photosensitive drum with light to form a latent image, it is necessary to control the laser beam with high precision, but the laser optical system and mechanism for this are complex. Therefore, the exposure means is expensive. Further, even if an LED (light emitting diode) array method is adopted as the exposure means, in the conventional method, the LED array has the size of the paper width, and within that width there are 1000 to 1000 dots corresponding to the number of recording dots. Since it constitutes a large number of LEDs, such as 2000, it becomes expensive. Furthermore, the price of photosensitive drums is high.

Second, the device becomes larger. Since the photosensitive drum occupies a large space, it is difficult to downsize it.

Further, regarding the exposure means, in the laser beam method, the laser optical system and the mechanism section occupy a large space, and in the LED array method, the LED array has the width of the paper, so it is large in size.

Third, maintenance cycles are short. Many parts, such as the photosensitive drum 100 and the developing device 108, require periodic replacement, resulting in high maintenance costs.

As described above, conventional electrophotographic printers have had many obstacles to miniaturization and low price required for widespread use.

If the printer is a color printer, developing devices for four colors, yellow, cyan, magenta, and black, are required, which further increases the disadvantages of increased device size, price increase, and increased maintenance costs.

The present invention has been made in view of these problems, and an object of the present invention is to provide an electrophotographic color printer that is smaller in size, lower in price, lower in maintenance cost, and can easily achieve high-speed and high-quality printing. purpose.

[Means for Solving the Problems] In order to achieve the above object, the electrophotographic color printer of the present invention has an endless belt base coated with a photoconductive material, and a continuous plurality of photoconductive materials on a sheet of paper. One-on-one with printing line
A photosensitive belt with a plurality of corresponding strip areas set;
A belt driving means that causes the photosensitive belt to run close to the paper in a direction perpendicular to the feeding direction of the paper; an exposure means for recording printing information of each color as an electrostatic latent image on the photoreceptor belt; by depositing a pigment of each color on each band-shaped area of the photosensitive belt on which the latent image is formed;
a developing means for visualizing the latent image of each color; and a developing means for developing a latent image of each color; The belt start/stop control means for stopping or starting the belt; and means for transferring a visible image on each band-shaped region of the photosensitive belt stopped at a predetermined position onto a sheet of paper.

When a developing device that performs wet development for each color is provided as a developing means, a high quality color image without color mixture can be obtained for the reasons described below.

[Operation] The photosensitive belt runs in a direction perpendicular to the paper, and the exposure means irradiates each band-shaped area of the running photosensitive belt with light corresponding to the print information of each color, so that the print information of each color is printed on each band-shaped area. form an electrostatic latent image corresponding to The electrostatic latent image on each of these band-shaped areas is visualized in a predetermined color by being coated with a dye of a corresponding color in a developing means. Next, under the control of the belt start/stop control means, the photosensitive belt is stopped at a predetermined position relative to the paper. Here, the transfer means is activated and each negative visible image on each band-shaped area of the photosensitive belt is transferred to the paper. As a result, an image of one color is simultaneously formed for each line in a plurality of consecutive print lines on the paper.

When one transfer is completed, the paper is fed in a predetermined direction by a pinch of one print line (one line), and in this state, the same operation as above is repeated. As a result, an image of one color per line is simultaneously formed on the paper over a plurality of print lines shifted by one print line from the previous print line.

In this way, images of a plurality of predetermined colors are overlaid on each printing line, and an image of a desired color is obtained by acidic mixing of the colors.

When a wet-type developing device is used, the toner liquid is immediately fixed when it is transferred to the paper during the transfer process, so even if a different toner liquid is transferred from above the next time, there is no fogging phenomenon, and color mixing is avoided. You can obtain high-quality color images without any blemishes.

[Embodiment] Hereinafter, the present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 1 is a diagram showing the main part of the internal structure of an electrophotographic color printer according to an embodiment of the present invention, and FIG. 2 is a diagram showing the correspondence between the belt-shaped area of the photosensitive belt and each color belt according to this embodiment. It is.

The photosensitive belt 10 is an endless belt base made of metal or conductive plastic coated with a photoconductive material. As shown in FIG. 2, four rows of strip areas sy, sM, SC, and SBk are set on the surface of the photosensitive belt 10. The pitch P of these strip-shaped areas is selected to be equal to the pitch of the printing lines on the paper 12, and therefore, these four-line strip-shaped areas correspond one-to-one to the four consecutive printing lines (opposed). do. These band-shaped areas S Y, S N, S C, and S Bk are each yellow (Y).

It is used to print one print line of magenta (M), cyan (C), and black (BK).

In FIG. 1, the photosensitive belt 10 is wound around pulleys 14 and 16 so as to be able to run in a direction (indicated by the arrow) perpendicular to the feeding direction (arrow A) of the paper 12 at a position close to and opposite to the paper 12. ing. The pulley 14 on the driving side is connected to the clutch 1
8 to a drive motor 20. Pulley 1
4.16, the clutch 18, the drive motor 20, etc. constitute a belt drive means 22. Although the details are omitted, this belt driving means 22 is controlled by a belt start/stop control circuit to move a visible image visualized on each band-shaped area of the photosensitive belt 10 to a predetermined position on the paper 12, as will be described later. The photosensitive belt 10 is properly stopped or started so that images can be printed correctly.

Facing the photosensitive belt 10, a static elimination lamp 24. cleaner 2
6, corona discharger 28, LED array 30, developing device 3
2 are arranged in order in the belt running direction.

The charge eliminating lamp 24 exposes the entire surface of the photosensitive belt 10 to remove all charges from the photosensitive belt 10. The cleaner 26 mechanically removes the pigment on the surface of the photoreceptor belt 10 that has been neutralized. Corona discharger 2
8 charges the surface of the photosensitive belt 10 negatively.

The LED array 30 is connected to each strip area S of the photosensitive belt 10.
Y, S M, S c, S Bk each color Y, M, C, BK
By irradiating the light corresponding to the print information of each color, changing the irradiated part into a conductor and losing the electric charge in that part, each color Y is printed on each strip area S Y, S M, S C, S Bk. , M, C, BK print information as an electrostatic latent image, and includes four blocks of LEDs arranged in a line in the belt width direction. The number of LEDs included in each block is the number required in the vertical direction to print one line, and is usually within several tens of LEDs.

The developing device 32 includes a developing device 32a for magenta (M) and black (BK), and a developing device 32a for yellow (Y) and cyan (C).
It consists of b. The developing device 32a applies M and BK toner liquids to the second and fourth row strip areas SM of the photosensitive belt) 10.
, SBk, respectively. The developing device 32b is Y
, C to the first and third row strip areas S Y, S
Color Bran 32Y for attaching each to C
, 32C.

As shown in FIG. 2, four color 0 bluffs 32Y, 32M, 32C, and 328K are opposed to four rows of strip areas S Y, S N, S C, and S Bk of the photosensitive belt 10, respectively. As a result, the color brush 32Y applies a positively charged toner liquid onto the first row strip area SY where the Y latent image is formed, using a wet development method, and visualizes the Y latent image. . By similar action, color brush 32M
, 32C, and 328 have the second, third, and fourth rows, respectively.
The latent images of M, C, and BK are visualized on the row strip areas SM and SCSBk. In addition, color m-brush 32Y, 32M, 3
2C and 328 are arranged in a staggered manner so as not to create gaps in the vertical direction, thereby preventing gaps (color omission) from occurring at the boundaries of each strip area.

Returning to FIG. 1, in this embodiment, corona discharger 28, L
ED array 30. The developing device 32 is placed on the side of the photosensitive belt 10 that approaches the paper 12, that is, near the driven pulley 16, and the static elimination lamp 24 and the cleaner 26 are placed on the side of the photosensitive belt 10 that moves away from the paper 12, that is, the drive pulley 16. It is placed near the pulley 14.

A photosensitive belt guide 34 is provided inside the portion of the photosensitive belt 10 that faces the paper 12, and a transfer device 36 is provided opposite the guide 34 side. This transfer device 36, which is a charger, is movable toward the photosensitive belt guide 34 as shown by the arrow (c), and charges the paper 12 while transferring the paper 12 onto the photosensitive belt 10 using the photosensitive belt guide 34 as a support. Press each band-shaped area S Y of the photosensitive belt 10,
S.M.

The toner liquid on SC and SBk is electrostatically transferred to the paper 12.

The roller 38 is used to feed the paper by sandwiching the paper 12 between it and the roller 40.
It is rotationally driven via a belt 48 wrapped around the 4.48. Note that, in this embodiment, development and transfer are performed in a wet manner, so that no fixing section is provided.

Next, the printing operation of the color printer having such a configuration will be explained.

When one printing is completed, the photosensitive belt 10 is started by the belt start/stop control circuit, and the direction of the arrow (
Drive in the direction of b). At this time, the photoconductive layer on the photosensitive belt 10 is turned into a conductor by the light from the static eliminating lamp 24 and loses charge. Therefore, the photosensitive belt 10 loses its ability to adsorb the toner liquid remaining after the previous transfer, and the toner liquid of each color on each strip area of the photosensitive belt 10 is easily removed by the subsequent cleaner 26.

The photosensitive belt 10, which continues to run, is connected to a corona discharger 28.
One side is negatively charged, and the following LED array 3
At 0, light corresponding to print information of each color Y, M, C, BK is emitted from each block into each strip area S Y, S M, S
C, SBk are each irradiated.

As a result, the areas exposed to the light become conductive and lose charge, so that print information of each color Y, M, C, BK is sequentially transferred to each band-shaped area S Y, S M as an electrostatic latent image.

They are recorded in SC and SBk respectively.

Subsequently, when reaching the developing device 32, color brushes 32Y, 32M, 32C, and 328K are applied to each band-shaped area S Y, S M, S (:, S Bk) of the photosensitive bell) 10, respectively.
contact, and the positively charged toner liquids of each color Y, M, C, BK are attracted to the negative charges of each strip area S Y, S M, S C, S Bk, and each latent image is formed in a predetermined color. It is visualized in In this way, visible images of four colors in four rows are simultaneously formed on the traveling photosensitive belt 10 one after another.

Then, when these visible images face a predetermined position on the paper 12 to be printed, the photosensitive belt 10 is stopped by the belt start/stop control means. Next, the transfer device 36 transfers the paper 1
2, move in the direction of the arrow (C) and press the paper 12 onto the photosensitive belt 10 using the photosensitive belt guide 34 as a support, and each strip area S Y, S M, S
The toner liquids of each color of C, S and Bk are transferred onto the paper 12.

As a result, the paper 12 has four printing lines Ll and L2.
．． L3. Over L4, images of each color of Y, M, C, and BK are formed one row at a time from the top.

In this way, when the transfer of 4 rows and 4 colors is completed, the paper 12 is 1
The printing line (one line) is sent in the direction of the arrow (A) by the pitch P, and in this state, the same operation as above is repeated.

As a result, the image of Y is printed on the printing line L2 of the paper 12.
The image of M is on the printing line L3, and the image of C is on the printing line L4.
An image of BC is formed on the new printing line L5. In this way, each printing line Ln
Four color images of BK, C, M, and Y are superimposed and printed on top of each other in the order of BK, C, M, and Y, and as a result of subtractive mixing of these images, an image of a desired color is obtained.

In the electrophotographic color printer configured as described above,
Since the LED array 30 only needs to have the width of the photosensitive belt 100 (four printing lines) and the number of LEDs can be, for example, 100 or less, it is possible to achieve significant downsizing and cost reduction.

In addition to the LED array 30, the static elimination lamp 2
4, Cleaner 2E31 Corona discharger 28, Developing device 32
All of the components need to correspond to the width of the photosensitive belt 10, making them significantly more compact than the conventional photosensitive drum system, which requires components corresponding to the paper width. Regarding the exposure itself, since it is belt-shaped,
It is significantly smaller than the photosensitive drum method.

Also, the photosensitive belt 10. Since regularly replaced parts such as the developing device 32 are small and inexpensive, maintenance costs are significantly reduced.

Since four-color printing is simultaneously performed on four printing lines, high-speed printing is realized.

Furthermore, in the transfer process, since the toner liquid is fixed immediately after being transferred to the paper 12, no fogging phenomenon occurs. In this regard, when dry development is used, a toner image of a different color is overlaid in the next transfer on top of a toner image that is not fixed without a special fixing process, resulting in so-called fogging and color mixing. The problem is that it is easy for this to occur.

In the embodiment, development was performed in four colors: yellow, magenta, cyan, and black, but it is also possible to perform development in three colors excluding black. In that case, the belt-shaped area of the photoreceptor belt 10 is
Only one line is set.

[Effects of the Invention] Since the present invention is configured as described above, it produces the following effects.

CI) The exposure means that forms a latent image on the photosensitive belt according to printing information only needs to correspond to the width of the photosensitive belt.
This exposure means can be significantly reduced in size and cost. Further, since the charging device, the developing means, and the toner liquid (dye) removing means are all required for the width of the photosensitive belt, these parts can be made smaller and cheaper. Therefore, the entire device can be significantly downsized and inexpensive.

(n) Since the photosensitive belt, developing device, etc. that require periodic replacement are also inexpensive, maintenance costs are reduced.

(III) Since printing in a plurality of colors (four colors) is performed simultaneously for a plurality of printing lines (for example, four lines), a printing speed that is faster (four times) faster than printing one printing line at a time can be achieved.

(IV) By performing wet development, the toner liquid is fixed immediately after being transferred to the paper in the transfer process.
No fogging occurs even when overcoating is performed, and good print quality without color mixture can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the main part of the internal structure of an electrophotographic color printer according to an embodiment of the present invention, and FIG. 2 is a diagram showing the correspondence between each strip area of the photosensitive belt and each color belt in the embodiment. FIG. 3 is a schematic side view of a conventional electrophotographic printer. In the drawings, 10...photosensitive belt, 12...paper, 16...belt driving means, 28...corona discharger (charging device), 30...
LED array (exposure means), 32...developing device, 34...transfer device.

Claims (2)

[Claims] (1) A photosensitive belt formed by applying a photoconductive material to an endless belt base, and having a plurality of band-shaped areas corresponding one-to-one to a plurality of continuous printing lines on a sheet of paper; and the photosensitive belt. A belt driving means for driving a belt close to the paper in a direction perpendicular to the paper feeding direction; an exposure means for recording print information of each color as an electrostatic latent image; and a dye of each color is deposited on each band-shaped region of the photosensitive belt on which the latent image is formed, thereby making the latent image of each color visible. a developing means for forming an image; and properly stopping the photosensitive belt so that the visible image of each color developed on each band-shaped area of the photosensitive belt can be correctly printed on each corresponding printing line of the paper; Alternatively, an electrophotographic color printer comprising: a belt start/stop control means for starting the belt; and means for transferring the visible image on each band-shaped region of the photosensitive belt stopped at a predetermined position onto a sheet of paper. (2) The electrophotographic color printer according to claim 1, wherein the developing means performs development of each color by a wet method.