JPH10319668A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a color image by a small number of buffers, without making a device constitution complicated. SOLUTION: On a first photoreceptor, a toner image of the K(black) color is formed at the first time of the image read-out. On the second photoreceptor 20, the toner image of the Y(yellow) color is formed with the delayed time from the first read-out time point of the image being arranged with a specific space (d) between the first photoreceptor 10 corresponding to the space (d). On the third photoreceptor 30, the toner image of M(magenta) color is formed, which is arranged with the space as, the space between the second photoreceptor 20 making the paper sheet not possible to reach until the toner image of the Y color is completely transferred on the paper sheet, and made to correspond to the image in company with the read-out of the image at the second time. The toner image of the C(cyan) color is formed corresponding to the image with the delayed time from the time point corresponding to the space (d') from the time second read out point of the image arranged with the specific space (d') between the third photoreceptor 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus for transferring images formed of different color materials formed on a plurality of photosensitive members onto a sheet in a superimposed manner.

[0002]

2. Description of the Related Art A color image forming apparatus such as a color copying machine which has begun to spread in recent years has been known as a CCD (Ch.
(Arge Coupled Device) The original image is reproduced by reading the image with an image reading device including an imager or the like, converting the image into a digital signal, and transferring a plurality of color toner images based on the image data onto a sheet.

In this color image forming apparatus, a plurality of photoconductors are arranged substantially horizontally and in series, an image for each color component is formed on each photoconductor, and an original image is reproduced by superimposing on one sheet of paper. Some adopt a so-called tandem system.

A so-called tandem type color image forming apparatus usually has a memory for holding at least one page of image data corresponding to each color material, and outputs data from the memory corresponding to each color in accordance with the sheet conveyance timing. And
Images are sequentially formed on the photoconductor corresponding to each color.

Further, from the viewpoint of reducing the memory capacity, a technique is used in which the memory is replaced with a buffer corresponding to the distance between the photoconductors provided corresponding to the different color materials and the paper transport speed (for example, Japanese Unexamined Patent Publication (Kokai) No. 61-196668) and a technique of adjusting the length from a recording point on a photoreceptor provided corresponding to a different color material to a transfer point on a sheet to eliminate the need for a memory (for example, JP-A-62-23
No. 8587) has been considered.

[0006]

However, in the technology in which the memory is replaced with a buffer corresponding to the distance between the photoconductors provided for the different color materials and the paper transport speed, a page memory is used. Although the memory capacity can be reduced as compared with the case, it is necessary to prepare buffers for at least three colors corresponding to each color.

[0007] Further, in the technology in which the length from the recording point on the photosensitive member provided for the different color material to the transfer point on the paper is adjusted to eliminate the need for the memory, the memory can be eliminated. However, this increases the size and complexity of the mechanism around the photoconductor.

[0008]

SUMMARY OF THE INVENTION The present invention is a color image forming apparatus made to solve such a problem.
That is, the color image forming apparatus of the present invention reads the image, forms the first color toner image corresponding to the image, and transfers the first color toner image to the sheet conveyed at a predetermined point. The photoreceptor is arranged at a predetermined distance from the first photoreceptor, and a second color toner image corresponding to the image is formed with a delay time corresponding to the distance from the time of reading the image. The distance between the second photoreceptor that transfers the second color toner image on the first color toner image transferred to the paper at the point and the second photoreceptor is such that at least the second color toner image is entirely on the paper. The image is arranged at a distance that does not allow the paper to reach until it is transferred to the image, and the image is read again, a third color toner image corresponding to the image is formed, and the second color transferred to the paper at a predetermined point A third photosensitive member for transferring a third color toner image onto the toner image of the third color, and a delay time corresponding to the distance from the point at which the image is read again while being arranged at a predetermined distance from the third photosensitive member. And a fourth photoconductor that transfers a fourth color toner image onto the third color toner image transferred to the paper at a predetermined point at which a fourth color toner image corresponding to the image is formed. ing.

When the image is read, a first color toner image corresponding to the image is formed, and after a predetermined delay time from the image reading time, a second color toner image corresponding to the image is formed.
A first photoreceptor for forming a first color toner image on a sheet conveyed at a predetermined point, wherein the first color toner image is formed on the first color toner image;
The distance from the first photoconductor is set such that at least the first color toner image and the second color toner image do not reach the paper until all the toner images are transferred onto the paper. Is formed, a fourth color toner image corresponding to the image is formed on the third color toner image after a predetermined delay time from the time when the image is read again, And a second photoconductor for transferring the third color toner image and the fourth color toner image onto the first color toner image and the second color toner image transferred to the paper at a predetermined point. It is also a color image forming apparatus.

In the present invention, the first photoconductor and the second photoconductor are arranged at a predetermined distance from each other, and the second photoconductor and the third photoconductor are transferred to the paper by at least the second photoconductor. Until all the toner images of the color are transferred to the sheet, the sheet is arranged with a distance such that the sheet does not reach the third photoconductor, and the third photoconductor and the fourth photoconductor are arranged with a predetermined distance therebetween. Therefore, the first color toner image is formed in the first image reading and transferred to the sheet, and the second color toner image is formed with a slight delay, and the second color toner image is formed on the first color toner image. After the transfer of the toner image, the third color toner image is formed by reading the image again, and when the toner image is transferred to the paper, the second color toner image is completely transferred to the paper.

In other words, a predetermined buffer is used to transfer the second color toner image after delaying the transfer of the first color toner image, but the second color toner image is transferred when the third color toner image is transferred. Since the toner image has been completely transferred, the buffer for the delay is empty. Therefore, the third color toner image can be transferred when the image is read again, and the fourth color toner image can be transferred to the empty buffer, and the fourth color toner image can be transferred using the same buffer. The transfer of the image can be slightly delayed from the transfer of the toner image of the third color.

A first color toner image is formed on the first photoreceptor, a second color toner image is formed on the first color toner image with a slight delay, and then transferred to a sheet. By arranging the photoconductor and the second photoconductor at a distance such that the paper does not reach until at least all of the first color toner image and the second color toner image are transferred to the paper, the first image is formed. A first color toner image is formed by reading, a second color toner image is formed on the first color toner image with a slight delay, and these toner images are transferred to paper, and then image reading is performed again. When the third color toner image is formed, the first color toner image and the second color toner image are completely transferred to the sheet.

That is, a predetermined buffer is used to form the second color toner image after delaying the formation of the first color toner image, but the first color toner image is formed when forming the third color toner image. Since the toner image of the second color is completely transferred to the sheet, the buffer for the delay becomes empty. Therefore, the third color toner image can be formed when the image is read again, and the fourth color toner image can be transferred to the empty buffer, and the fourth color toner image can be transferred using the same buffer. The image formation can be slightly delayed from the formation of the third color toner image.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a color image forming apparatus according to an embodiment of the present invention. FIG.
FIG. 1 is a configuration diagram illustrating a first embodiment of the color image forming apparatus of the present invention. That is, the color image forming apparatus 1 in FIG. 1 employs a so-called tandem system in which a plurality of photoconductors are arranged substantially horizontally and in series, and a sheet conveyed along a sheet conveying direction (see an arrow in the figure). To
The image of each color component is sequentially superimposed and transferred from each photoconductor, and the original image is reproduced.

The color image forming apparatus 1 according to the first embodiment includes a first photosensitive member 10 corresponding to black (K) image formation and a first photosensitive member corresponding to yellow (Y) image formation along the upper surface of the conveyor belt B. Four photoconductors 20, a second photoconductor 20, a third photoconductor 30 corresponding to magenta (M) image formation, and a fourth photoconductor 40 corresponding to cyan (C) image formation are arranged at a predetermined distance. ing.

Around the first photoreceptor 10, a charging charger 11, a laser beam 12, a developing device 13, and a transfer device 14 are arranged. Around the second photoreceptor 20, a charging charger 21, a laser beam 22, a developing device 23, and a transfer device 24 are arranged. Around the third photoconductor 30, a charging charger 31, a laser beam 32, a developing device 33,
A transfer device 34 is disposed, and around the fourth photoconductor 40,
Charger 41, laser beam 42, developing device 4
3. A transfer device 44 is provided.

The first, second, third, and fourth photoconductors 10, 20, 30, 40 are charged chargers 11, 21, 31, and 41, respectively.
Are charged uniformly. The laser beams 12, 22, 32, and 42 form electrostatic latent images corresponding to respective color components on the surfaces of the first, second, third, and fourth photoconductors 10, 20, 30, and 40, respectively. It is.

The developing devices 13, 23, 33, and 43 include first, second, third, and fourth photoconductors 10, 20, 30, 40, respectively.
A toner of a color component corresponding to each electrostatic latent image formed on the surface of each is attached to form a toner image. Further, the transfer devices 14, 24, 34, 44 are first, second,
The toner image of each color component formed on the surface of each of the third and fourth photoconductors 10, 20, 30, and 40 is transferred onto a sheet conveyed along the conveyance belt B.

In the color image forming apparatus 1 according to the first embodiment, the first, second, third, and fourth photoconductors 10, 20, 3
The diameters of 0 and 40 are equal, and their peripheral speeds are also equal.

Here, in each of the first, second, third, and fourth photoconductors 10, 20, 30, and 40, the forming point of each electrostatic latent image by the laser beams 12, 22, 32, and 42. To the image recording points, transfer devices 14, 24, 34, 44
Is referred to as an image transfer point.

In the color image forming apparatus 1 according to the first embodiment, the first photoconductor 10, the second photoconductor 20,
The arrangement of the third photoconductor 30 and the fourth photoconductor 40 is characteristic.

That is, in the color image forming apparatus 1, a K color electrostatic latent image is recorded by the laser beam 12 of the first photosensitive member 10 while reading the image, and a K color toner image is formed on the paper at the image transfer point. After the transfer, the Y-color electrostatic latent image corresponding to the read image is recorded in the second
The Y-color toner image is transferred so as to be superimposed on the K-color toner image on the sheet at the image transfer point by the laser beam 22 of the photoconductor 20, and the first photoconductor 10 and the second photoconductor 20 are transferred.
Is set in accordance with the delay time in image recording on the second photoconductor 20.

The distance c between the first photoconductor 10 and the third photoconductor 30 is a distance along the surface of the first photoconductor 10 from the image recording point of the first photoconductor 10 to the image transfer point. , Third
When the distance along the surface of the third photoconductor 30 from the image recording point of the photoconductor 30 to the image transfer point is b, and the maximum time including the scan and return in reading the image x the peripheral speed of the photoconductor is N , A + c−b ≧ N.

That is, until at least the toner image of the Y color is completely transferred onto the paper by the second photoconductor 20, the third photoconductor 30 is separated by a distance such that the paper does not reach the image transfer point of the third photoconductor 30. Is arranged.

The distance c 'between the second photoconductor 20 and the fourth photoconductor 40 is a distance along the surface of the second photoconductor 20 from the image recording point of the second photoconductor 20 to the image transfer point. a ',
The fourth photosensitive member 40 from the image recording point to the image transfer point
Assuming that the distance along the surface of the photoconductor 40 is b 'and the maximum time including the scan and return in reading the image x the peripheral speed of the photoconductor is N', the relationship is a '+ c'-b'≥N'. To meet.

Further, in the color image forming apparatus 1,
When the image is read again, an M electrostatic latent image is recorded by the laser beam 32 of the third photoconductor 30, an M color toner image is transferred to the paper at an image transfer point, and the image corresponds to the read image again. The C electrostatic latent image is recorded with the laser beam 42 of the fourth photosensitive member 40 after a predetermined delay time, and the C color toner image is superimposed on the M toner image on the paper at the image transfer point. Although the image is transferred, the distance d ′ between the third photoconductor 30 and the fourth photoconductor 40 is set according to the delay time in image recording on the fourth photoconductor 40.

The distance d between the first photoconductor 10 and the second photoconductor 20 and the distance d 'between the third photoconductor 30 and the fourth photoconductor 40
Are set to the same length corresponding to the delay time in image recording (transfer), respectively, and a predetermined buffer is used to provide this delay time. FIG. 2 is a configuration diagram illustrating the buffer.

That is, in order to send a signal corresponding to a predetermined color component to the color image forming apparatus 1 in this embodiment, the image read by the image
(Red), G (Green), and B (Blue) components, and the RGB components are converted into K (Black), M (Magenta), Y (Yellow), and C (Cyan) by the color space conversion device 200. Has been converted to. At this time, when the Y signal corresponding to the second photoconductor 20 and the C signal corresponding to the fourth photoconductor 40 shown in FIG. 1 are transmitted to the color image forming apparatus 1, a predetermined delay time is passed through the same buffer BF. And send it.

That is, in the color image forming apparatus 1 of the present embodiment, in the first image reading, an image of K color is formed by the first photoconductor 10 in synchronization with the reading, and the predetermined image is formed via the buffer BF. After a delay time, the Y-color image is formed on the second photoconductor 20. The capacity of the buffer BF is determined by the distance d (see FIG. 1) between the first photoconductor 10 and the second photoconductor 20.

Further, until the second photoreceptor 20 and the third photoreceptor 30 transfer at least all the Y color toner images onto the paper by the second photoreceptor 20, the paper is transferred to the image transfer position of the third photoreceptor 30. Are arranged so that they do not reach each other, the image transfer on the second photoconductor 20 is completed before the paper reaches the third photoconductor 30. That is, the buffer BF is already empty when the paper reaches the third photoconductor 30.

Therefore, in the second image reading, an M-color image is formed on the third photosensitive member 30 in synchronization with the reading.
When the C-color image is formed by the fourth photosensitive member 40 after a predetermined delay time, the C-color signal for performing image recording by the fourth photosensitive member 40 is transferred to the same buffer BF as before.
Will be able to accumulate.

FIG. 3 is a timing chart in image formation. Color image forming apparatus 1 in the present embodiment
Read the original image twice. That is, first, the K color image is written in synchronization with the first reading, and the Y color writing is performed after a predetermined delay time t by the buffer.

Next, after the writing of the Y color is completed (the buffer BF shown in FIG. 2 becomes empty at this time) and the return time R of the image reading has elapsed, the second reading is performed. M image is written in synchronization with Then, the C color is written after a predetermined delay time t by the buffer (the same one as above).

The first, second, third, and fourth photosensitive members 10, 20, 30, 40 in such a color image forming apparatus 1.
With this arrangement, if only one buffer BF having a small capacity is prepared, image formation corresponding to all colors can be performed.

Next, a second embodiment of the color image forming apparatus of the present invention will be described with reference to FIG. In the second embodiment shown in FIG. 4, a so-called double color image forming apparatus 1 for forming an image of four colors mainly by two photoconductors is used as an example.

In the color image forming apparatus 1 according to the second embodiment, the first photosensitive member 10 and the second photosensitive member 20 are arranged along the upper surface of the conveyor belt B at a predetermined distance c. Around the first photoconductor 10, a charging charger 1 is provided.
1, laser beam 12 corresponding to K (black), developing device 13 corresponding to K (black), laser beam 22 corresponding to Y (yellow), developing device 23 corresponding to Y (yellow), transfer device 1
A charging charger 21 and a laser beam 3 corresponding to M (magenta) are provided around the second photoconductor 20.
2, a developing device 33 corresponding to M (magenta), a laser beam 42 corresponding to C (cyan), a developing device 43 corresponding to C (cyan), and a transfer device 24 are arranged.

The chargers 11 and 21 charge the surfaces of the first and second photoconductors 10 and 20 uniformly. The laser beam 12 forms an electrostatic latent image corresponding to the color K on the surface of the first photoconductor 10, and the developing device 13 forms a toner image by attaching the toner of the color K corresponding to the electrostatic latent image. .

The laser beam 22 is arranged such that its image recording point is separated from the laser beam 12 on the surface of the first photosensitive member 10 by a distance d, and forms an electrostatic latent image corresponding to the Y color. The developing device 23 applies Y color on the K toner image.
The color toners are superposed and adhered.

The laser beam 32 forms an electrostatic latent image corresponding to the color M on the surface of the second photoreceptor 20, and the developing device 33 attaches the toner of the color M corresponding to the electrostatic latent image to form a toner image. To form The laser beam 42 is arranged such that its image recording point is separated by a distance d ′ on the surface of the second photoconductor 20 from the laser beam 32, and forms an electrostatic latent image corresponding to C color. The C color toner is superimposed and adhered on the M color toner image. Note that this distance d '
Is the same as the distance d described above.

The transfer devices 14 and 24 include the first and second photosensitive members 1
The toner images of the respective color components formed on the respective surfaces 0 and 20 are transferred onto a sheet conveyed along the conveyor belt B.

The first photoconductor 10 and the second photoconductor 2
0 have the same diameter and the same peripheral speed.

The buffers used in the color image forming apparatus 1 according to the second embodiment are the same as those shown in FIG. That is, the distance d between the image recording point where the electrostatic latent image corresponding to the K color is formed on the first photoconductor 10 and the image recording point where the electrostatic latent image corresponding to the Y color is formed, and the second photoconductor 20 The capacity is determined according to the distance d 'between the image recording point for forming the electrostatic latent image corresponding to M color and the image recording point for forming the electrostatic latent image corresponding to C color. The Y color is delayed from the color and the C color is delayed from the M color by a predetermined time.

The distance c between the first photoreceptor 10 and the second photoreceptor 20 is different from the surface of the first photoreceptor 10 from the image recording point corresponding to the K color of the first photoreceptor 10 to the image transfer point. The distance along the surface is a, the distance along the surface of the second photosensitive body 20 from the image recording point corresponding to the M color of the second photosensitive body 20 to the image transfer point is b, and the scan and return in reading the image are combined. Assuming that “maximum time × peripheral speed of the photoconductor” is N, a relationship of a + c−b ≧ N is satisfied.

That is, the distance at which the sheet does not reach the image transfer point of the second photoconductor 30 until at least all of the K and Y toner images superimposed on the first photoconductor 10 are transferred onto the paper. Is opened and the second photoconductor 20 is disposed.

In the color image forming apparatus 1, in the first image reading, an image of K color is formed by the laser beam 12 and the developing device 13 of the first photosensitive member 10 in synchronization with the reading, and the buffer BF (see FIG. After a predetermined delay time, the laser beam 22 and the developing device 23 form a Y color toner image on the K color toner image.

When the sheet is conveyed by the conveying belt B and reaches the image transfer point of the first photosensitive member 10, the K toner image and the Y toner image are simultaneously transferred onto the sheet by the fixing device 14. become.

When the paper reaches the second photosensitive member 20, the transfer of the K color toner image and the Y color toner image to the paper has been completed. As a result, the buffer BF (see FIG. 2) used for delaying the Y-color image formation is empty.

Therefore, in the second image reading, an M color image is formed in synchronism with the reading by the laser beam 3.
2 and the developing device 33 to form a C-color image after a predetermined delay time.
, The C color signal is transferred to the same buffer BF as before.
(See FIG. 2).

The timing of image formation in the second embodiment is the same as the timing of image formation in the first embodiment (see FIG. 3). That is, first, the K color image writing is performed in synchronization with the first reading, and the Y color writing is performed after a predetermined delay time t by the buffer.
Next, after the writing of the Y color is completed (the buffer BF shown in FIG. 2 becomes empty at this time) and the return time R of the image reading has elapsed, the second reading is performed, and in synchronization with the second reading. To write an M color image. Then, the C color is written after a predetermined delay time t by the buffer (the same one as above).

As described above, even in the so-called double-type color image forming apparatus 1, if only one buffer BF having a small capacity is prepared by the arrangement of the first and second photoconductors 10 and 20, all the colors are formed. Can be formed.

[0051]

As described above, according to the color image forming apparatus of the present invention, the structure of the apparatus is not complicated by the positional relationship between the respective photoconductors and two image readings.
In addition, a color image can be reproduced by delaying only one buffer, and the size and cost of the apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a first embodiment.

FIG. 2 is a configuration diagram illustrating a buffer.

FIG. 3 is a timing chart in image formation.

FIG. 4 is a configuration diagram illustrating a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Color image forming apparatus 10 1st photoreceptor 11, 21, 31, 41 Charger 12, 22, 32, 42 Laser beam 13, 23, 33, 43 Developing device 14, 24, 34, 44 Transfer device 20 2nd photosensitive Body 30 Third photoconductor 40 Fourth photoconductor B Transport belt

Claims (2)

[Claims] A first photoconductor that forms a first color toner image corresponding to the image while reading the image, and transfers the first color toner image to a sheet conveyed at a predetermined point; The first photoconductor is arranged at a predetermined distance from the first photoconductor, and a second color toner image corresponding to the image is formed with a delay time corresponding to the distance from the time of reading the image. The second color toner image is transferred onto the first color toner image transferred onto the paper sheet.
The distance between the photoconductor and the second photoconductor is set so that at least the second color toner image is not reached until the entirety of the second color toner image is transferred onto the paper, and the image is read again. A third photoconductor that forms a third color toner image corresponding to the image, and transfers the third color toner image onto the second color toner image transferred to the sheet at a predetermined point; A fourth color toner image corresponding to the third photoconductor is formed at a predetermined distance from the third photoconductor and at a delay time corresponding to the distance from a point at which the image is read again, A fourth photoconductor for transferring the fourth color toner image onto the third color toner image transferred to the sheet at a predetermined point. 2. A first color toner image corresponding to the image is formed when the image is read, and a second color toner image corresponding to the image is formed after a predetermined delay time from the image reading time. A first photoconductor that transfers the first color toner image and the second color toner image to a sheet formed on the first color toner image and conveyed at a predetermined point; and the first photoconductor. And at least a distance that the sheet does not reach until all of the first color toner image and the second color toner image are transferred to the sheet, and the image is read again when the image is read again. Is formed, and a fourth color toner image corresponding to the image is formed on the third color toner image after a predetermined delay time from the time when the image is read again. And where The at points transferred to the paper 1
The third color toner image on the color toner image and the second color toner image
A color image forming apparatus comprising: a color toner image; and a second photoconductor for transferring the fourth color toner image.