JP2731172B2 - Color recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a color recording apparatus such as a color printer, a color facsimile, and a color copying machine, and more particularly, to a transfer position of a transfer paper by a reciprocally movable transfer paper transport body. The present invention relates to a color recording apparatus that forms a color image on transfer paper by a superimposition transfer method in which images are reciprocated with respect to each other to superimpose images for each color separation.

(Prior Art) A photoreceptor is subjected to image exposure for each color separation of a document image to form an electrostatic latent image corresponding to each color, and then to a photoconductor for each color separation using a developer corresponding to each color. The latent image formed thereon is visualized, and the visualized image obtained for each color separation is transferred to a predetermined transfer position by a transfer paper transport belt capable of reciprocating and stopping operations. The transfer paper is transferred to the transfer section when the transfer paper transport belt moves forward (forward rotation), and the transfer is performed. When the transfer paper transport belt moves backward (reverse rotation), the transfer paper is transferred. The operation of returning to the previous position and stopping / waiting is sequentially repeated for each color transfer, and after the final color transfer is completed, the transfer paper is conveyed to a fixing device, and the image transferred to the transfer paper is fixed to correspond to the original image. 2. Description of the Related Art A superposition type color recording apparatus for obtaining a color image is known (for example, See, for example, JP-A-62-186282).

Incidentally, the color recording apparatus described in the above-mentioned publication is provided with a transfer paper separating static eliminator (13) for separating the transfer paper after the final color transfer from the transfer paper transport belt. The static eliminator (13) is disposed near a driving roller (2) for driving the transfer paper transport belt that supports the most downstream end side of the transfer paper transport belt (1).

(Problems to be Solved by the Invention) However, as in the color recording apparatus described in the above publication, when the transfer paper separating static eliminator (13) is arranged near the driving roller (2) for driving the transfer paper transport belt, The following problems occur.

When the transfer paper size is large, the transfer paper transport belt (1)
During forward movement, the leading edge of the transfer paper is separated from the transfer paper transport belt (1) at a portion corresponding to the drive roller (2), and at the time of backward movement, the rear end of the transfer paper is transferred at a portion corresponding to the driven roller (3). The transfer paper transport belt (1) is reciprocated so as to separate from the transport belt (1). In such a case, the corona application by the transfer charger (12) is performed twice or three times according to the number of transfers. If the electrostatic attraction between the transfer paper and the transport belt becomes very strong as the repetition is repeated, the leading and trailing ends of the transfer paper cannot be separated from the transfer paper transport belt (1) and are caught in the paper, resulting in transport failure. There is a possibility that. Therefore,
In order to prevent this, the transfer separating static eliminator (13) is operated not only at the time of the transfer paper separation and discharge at the end of the final color transfer process but also at the time of the reciprocating movement of the other transfer process to facilitate the separation of the transfer paper. Although a method is conceivable, since the transfer paper is discharged only from the leading end to the position of the separation static eliminator (13) at the arrangement position of the transfer separating static eliminator (13) as in the above-described publication, The charge potential of the transfer paper and the transfer paper conveyance belt is different between the charge elimination area and the area up to the trailing edge of the paper, and the transfer efficiency in the next transfer process is reduced. A problem arises that transfer image unevenness occurs differently from the region up to the above.

In addition, in the above-described method, since the trailing edge of the paper is not removed, there is also a problem that a conveyance failure at the time of returning is not solved at all.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and is a color recording apparatus that obtains a color image by superimposing color-separated images by repeating a plurality of transfer steps, which is uniform over the entire transfer paper. It is an object of the present invention to provide a color recording apparatus capable of obtaining a transfer image and preventing transfer paper conveyance failure in a transfer paper conveyance unit.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, an electrostatic latent image forming apparatus for forming an electrostatic latent image corresponding to each color for each color separation on a photosensitive member rotated at a constant speed. A developing process of developing a latent image formed on the photoconductor at each color separation using a developer corresponding to each color, and a reciprocating operation of an image visualized at each color separation. And a transfer process of transferring to a transfer sheet conveyed to a predetermined transfer position by a transfer sheet conveyer capable of stopping operation, is sequentially repeated, and the transfer sheet conveyer reciprocates one transfer sheet a plurality of times to expose the photosensitive sheet. In the color recording apparatus for superimposing and transferring the image for each color separation on the body, and after the final color transfer, transferring the transfer paper to a fixing device and fixing the image transferred to the transfer paper to obtain a color image, The transfer paper carrier is stretched between the drive roller and the driven roller. If the transfer paper size is larger than the belt length from the transfer position to the driving roller or driven roller,
During the reciprocation of the transfer paper transporter in the transfer process before the final color transfer process, the leading edge of the transfer paper separates from the transfer paper transporter at the portion corresponding to the drive roller and advances to the paper leading edge guide. The transfer paper transport body is reciprocated so that the end is separated from the transfer paper transport body at a portion corresponding to a driven roller and advances to a paper rear end guide portion, and the transfer paper is located near the downstream side of the transfer position. A static eliminator is provided, and during the transfer process, the transfer paper transport body is moved forward until the rear end of the transfer paper passes through the static elimination area by the transfer paper static eliminator, and then the transfer paper transport body is moved backward, At least once before the final color transfer step, in order to prevent transient electrostatic attraction of the transfer sheet to the transfer paper transport body, in addition to the transfer sheet de-electrification for transfer sheet separation performed during the forward movement of the final color transfer step. The transfer paper static eliminator is also used during the forward movement of the transfer process Accordingly, it characterized by being configured to perform the transfer sheet static elimination.

(Operation) In the color recording apparatus having the above configuration, the transfer paper transporting body is a belt-like member stretched between a driving roller and a driven roller, and the transfer is performed based on a belt length from the transfer position to the driving roller or the driven roller. If the paper size is large, the leading edge of the transfer paper is separated from the transfer paper carrier by the drive roller equivalent portion and advances to the paper leading edge guide portion during the forward movement of the transfer paper carrier in the transfer process before the final color transfer process. When the paper is moved backward, the transfer paper transport member is reciprocated so that the rear end of the transfer paper separates from the transfer paper transport member at a portion corresponding to a driven roller and proceeds to a paper rear end guide portion. In the case of transfer paper having a size larger than the belt length from the transfer roller to the driven roller or the driven roller, the transfer can be performed by reciprocating with the transfer paper transport body, and the transfer paper is removed near the downstream side of the transfer position. In the transfer process, the transfer paper carrier is moved forward until the rear end of the transfer paper passes through the charge removal area by the transfer paper discharger during the transfer process, and then the transfer paper carrier is moved backward, so that the final Even during the reciprocating movement of the transfer paper transporter during the transfer process prior to the color transfer, it is possible to uniformly remove the charge from the leading edge to the trailing edge of the transfer paper, thereby preventing the occurrence of charging unevenness during the transfer.

In addition to the transfer paper discharging for transfer paper separation performed at the time of forward movement of the final color transfer process, the final color transfer is performed to prevent transient electrostatic attraction of the transfer paper to the transfer paper transport body (transfer paper transport belt). The transfer paper static eliminator is used to remove the transfer paper even during at least one forward movement of the transfer process before the transfer process, thereby preventing the transfer paper from being electrostatically attracted to the transfer paper transport belt. Thus, transfer failure of the transfer paper is prevented.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an example of a color printing apparatus suitable for carrying out the present invention, FIG. 2 is a timing chart showing the basic operation of the color printing apparatus, and FIG. Drive control system, FIG. 4 is a schematic view of a main part of a color recording apparatus when the present invention is applied to the color recording apparatus having the configuration shown in FIG. 1, and FIG. 5 is a color recording apparatus according to the present invention. In FIGS. 1, 3 and 4, reference numeral 1 denotes a photoreceptor belt (hereinafter referred to as a "PC belt"), and reference numeral 2 denotes the above-mentioned operation. A PC driving roller for supporting and rotating one end of the PC belt 1, reference numeral 3 denotes a PC driven roller for rotatably supporting the other end of the PC belt 1, and reference numeral 4 denotes a PC.
Charger for charging the belt 1;
An optical writing unit for forming an electrostatic latent image corresponding to each color, reference numerals 7, 9, 11, and 13 denote developing units for developing latent images corresponding to each color, and reference numerals 6, 8, 10, and 12 denote the above. Developing rollers provided in each of the developing units 7, 9, 11, and 13, reference numerals 14, 33, and 34 indicate transfer paper, and reference numeral 15
Is a paper feed roller for feeding the transfer paper 14 into the recording apparatus, reference numeral 16 is a registration roller, and reference numeral 17 is a transfer unit serving as a transport unit for transporting the fed transfer paper 14 to a transfer unit and a fixing unit. Reference numeral 18 denotes a driving roller for supporting and rotating one end of the transfer paper transport belt 17, reference numeral 19 denotes a driven roller for rotatably supporting the other end of the transfer paper transport belt 17, and reference numeral. Reference numeral 20 denotes a belt contact / separation switching roller for moving the transfer paper transport belt 17 toward and away from the PC belt 1, reference numeral 21 denotes a transfer corona for transferring a developed image on the PC belt 1 to the transfer paper 14, and reference numeral 22 denotes a transfer corona. A neutralizing corona for neutralizing the transfer paper transport belt 17, a reference numeral 23 denotes a transfer paper suction charger for electrostatically attracting the transfer paper 14 to the transfer paper transport belt 17, and a reference numeral 24 denotes an electrostatic charge to the transfer paper transport belt 17. A transfer paper separation static eliminator for separating the adsorbed transfer paper. Akira are shown a transfer sheet separation discharger 24 disposed position or transfer sheet discharger which is newly provided in the case of implementation, reference numeral 25 a transfer-sheet conveying belt
A transfer paper transport belt cleaner for removing paper dust, developer, etc. attached to 17, a reference numeral 26 is a paper path switching member for switching a transfer direction of the transfer paper after transfer, a reference numeral 27 is a paper leading end guide plate,
Reference numeral 28 denotes a paper rear end guide plate, and reference numeral 29 denotes a PC belt 1 after transfer.
PC belt cleaner, to remove residual toner on
Reference numeral 30 denotes a static eliminator for removing static electricity from the PC belt 1, reference numeral 31 denotes a fixing unit for fixing an image transferred to a transfer sheet, and reference numeral
31a is a fixing roller pair of the fixing device 31, 32 is a discharge tray for discharging transfer paper after image fixing, 35 is a color image reading device for reading a color image of a document, 36 is
Is a PC drive motor for rotating and driving the PC drive roller 2,
Reference numeral 37 denotes an encoder of the PC drive motor 36, reference numeral 38 denotes a rotation detection sensor mounted on the shaft of the PC drive roller 2, reference numeral 39 denotes a transfer drive motor for driving the transfer paper transport belt 17 drive roller 18, and reference numeral 40 denotes transfer drive. An encoder for detecting the rotation of the motor 39. Reference numeral 41 denotes a servo control drive circuit for the PC drive motor 36.
A main control circuit for controlling the servo control drive circuit 43 for the transfer drive motor 39 and the transfer drive motor 39 is shown.

The main control circuit 41 includes a well-known CPU, RAM and ROM.
, An I / O port, an input / output interface, a counter circuit, and the like.A control program and control data according to various copying processes are stored in advance in the ROM of the storage device. Have been.

Here, first, the copying operation of the color recording apparatus having the basic configuration shown in FIGS. 1 and 3 will be described.

In FIGS. 1 to 3, a print switch is used to start a print operation (see FIG. 2 (a)).
Is issued, control by the main control circuit 41 is started, an ON signal of the PC drive motor is output, and the PC belt 1
It is rotated clockwise at a linear velocity VP by the PC drive roller 2 which is rotated by the PC drive motor 36. In addition, PC belt 1
Is wound around the PC drive roller 2 and the PC driven roller 3. At the same time as the rotation of the PC belt 1, the transfer driving motor 39 of the transfer paper transport belt 17 consisting of a dielectric belt stretched over the drive roller 18 and the driven roller 19 also rotates forward (FIG. 2 (g)). ), (H), and (j)), and is rotated at a linear velocity VF in the forward movement direction. The traveling speed of the PC belt 1 and the transfer paper transport belt 17 is controlled so as to rotate under the condition of VP = VF.

After the toner on the surface of the PC belt 1 is removed by the cleaning device 29, the charge is removed by the charge remover 30 to make the surface potential substantially OV. After that, the PC belt 1 is uniformly charged by the charger 4 over the entire surface. Is done.

As the static eliminator 30, a light irradiating type, a type that applies a static elimination corona, or a combination of both is used. Further, in the case of the well-known negative-positive process, the toner is attached to an uncharged portion on the surface of the PC belt 1, and thus the charging by the charger 4 must be uniformly charged on the entire surface of the PC belt 1. . Also, this charger 4
Is uniformly performed by corona discharge, but slight ozone is generated during this discharge. This ozone is decomposed in a short time when the discharge is stopped, but may have an adverse effect on the surface of the PC belt 1 and impair the sharpness of the image. Therefore, a fan or the like is attached to send air from behind the charger, or suction is performed to remove ozone, thereby preventing the influence of ozone.

By the way, the axis of the PC drive roller 2 has a rotation detection sensor
As shown in FIG. 2 (d), a detection pulse is generated every rotation of this roller. In the case of the example shown in FIG. 2, the control of the semiconductor laser (hereinafter, referred to as LD) of the optical writing unit 5 is started at the timing of the third pulse of the rotation detection sensor, and first, based on the Y image data of the yellow image. The optical writing is started, and an electrostatic latent image is formed on the PC belt 1 at a point E in the figure. Note that, as the optical writing unit, another type of optical writing unit, such as another type of laser, LED array, or LCD array, may be used. The image data to be written is, for example, blue,
The three color separation lights of green and red are read, and a known image operation is performed based on the intensity level of each color light to obtain yellow (Y), magenta (M), cyan (C), and black (Bk). ) For each color. Note that, in addition to the color image reading unit 35, writing may be performed based on image data output from another color image processing system (for example, a color facsimile, a word processor, a personal computer, or the like).

A yellow (Y) developing device 7, a magenta (M) developing device 9, a cyan (C) developing device 11, and a black (B
k) Developing device 13 usually includes developing rollers 6, 8, 10, and 12 on a PC.
It is placed in a position where it does not contact the surface of the belt 1. Then, only during the period from immediately before the latent image surface of the corresponding color reaches the developing roller position of each color to immediately after passing, the developing device of the corresponding color is pressed and moved to bring the developing roller into contact with the photosensitive surface by a predetermined amount. It faces so that it may be in a state. In addition, as shown in FIGS. 2 (n) to 2 (p), only the developing device opposed to the photosensitive surface starts driving in order to have a developing function.

As described above, first, since a latent image of the Y image is formed on the photosensitive surface, the Y developing device 7 is brought into contact with the photosensitive surface at a timing with respect to the surface and driven (FIG. 2 ( m)) to visualize this.

Thereafter, the PC belt 1 proceeds to the transfer process.
At this time, the vertical position of the belt contact / separation switching roller 20 is switched so that the transfer paper transport belt 17 comes into contact with or separates from the belt surface at the transfer portion of the PC belt 1 wound around the PC drive roller 2. . Next, when the printing operation is started, the transfer paper transport belt 17 is driven at the speed VF, and then the belt contact / separation switching roller 20 is moved to the upper position, and the transfer paper transport belt 17 is moved.
17 is pressed to bring the PC belt 1 into contact (see FIG. 2 (t)).

Then, the transfer paper 14 is fed by the feed roller 15 at a timing according to the number of pulses of the encoder 37 of the PC drive motor 36 (see FIG. 2 (q)). The progress of the transfer paper is temporarily stopped by the registration roller 16, and the transfer paper is conveyed toward the surface of the transfer paper conveyance belt 17 at a timing so as to match the image position formed on the PC belt 1 (FIG. 2). (R)
reference). The conveyed transfer paper is subjected to corona charging of a predetermined polarity by a transfer paper adsorption corona charger 23 (see FIG. 2 (x)), and is brought into close contact with the transfer paper conveyance belt 17, so that the transfer paper is transferred and transferred during transfer. There is no misalignment with the belt. At this time, the belt contact / separation switching roller 20 functions as a counter electrode for corona discharge of the transfer paper suction charger 23. The transfer paper transport belt 17 is used to remove the static electricity before the first color transfer process.
The electric charge is eliminated by the entire surface corona discharge by 22 (see FIG. 2 (w)). At this time, the transfer paper transport belt 17
Is subjected to a cleaning process by the belt cleaner 25.

By the way, the tip of the visualized Y image on the PC belt 1 is
Upon reaching the TS point a predetermined distance from the transfer position T point, the transfer drive motor forward rotation start signal S ₁ is input to the drive control circuit 43 of the transfer drive motor 39 from the main control circuit 41 (second
FIG. (H)). However, the start S ₁ point, it is already forward rotation in (see FIG. 2 (j)), and continues the forward operation as it is. The output timing of the transfer driving motor forward rotation start signals S ₁ is substantially a point where the leading edge of the transfer sheet reaches the RT point is a position before a distance l ₁ from the transfer position T. At this time, the tip of the Y image of the PC belt 1 is a distance l _{1 from the} transfer position T.
In the control example shown in FIG. 2, the Y image data writing start timing (E
(Point), it is a time point when the rotation of the PC drive roller 2 has been performed by 4 rotations and further by the pulse number P ₀ of the encoder 37 of the PC drive motor 36 (FIGS. 2 (d), (e), (f), (H)).

When the time t ₁ has elapsed from the start signal S ₁ , the leading end of the Y image and the leading end of the transfer paper have both reached the transfer position T by moving a distance l _1, and have been subjected to corona discharge by the transfer corona charger 21 to receive the Y image. Transfer is started (see FIG. 2 (s)). At this time, the number of pulses of the encoder (PC) 37 of the PC drive motor 36 at time t ₁ is P ₁ , and the encoder (T) 40 of the transfer drive motor 39
Number of pulses is PT ₁ (FIG. 2 (e), see (k)). Here, as the resolution of both encoders, if the belt movement length per pulse is the same for each, P ₁ = PT
_1, also, if the ratio therebetween is alpha, P ₁ and PT ₁ becomes a value corresponding to the coefficient alpha.

The following description is based on the premise that the condition of P ₁ = PT ₁ is satisfied. The pulse number of the encoder (PC) 37 is P ₁
Are input to the control circuits 41 and 42.

By the way, when the Y image transfer process proceeds, the leading end of the transfer paper is separated from the transfer paper transport belt 17 and guided by the paper path switching member 26 placed at the solid line position, and advances on the paper leading end guide plate 27. I do. Then, the process proceeds more Y image transfer process, when the transfer sheet trailing edge has passed the transfer position T by a length l _2, that is, the transfer sheet from the start S ₁ point as indicated by reference numeral 34,
After the lapse of time t ₁ + t ₂ length l ₁ + l _p (transfer sheet size) + l ₂
Transfer distance, the transfer drive motor reverse rotation signal (second
(See FIGS. (I) and (j)) to rotate the motor in reverse. Simultaneously with or before this reverse rotation signal, the belt contact / separation switching roller 20 is moved to a lower position to move the transfer paper transport belt 17 in a direction to separate it from the PC belt 1.

By the reverse rotation of the transfer drive motor 39, the transfer paper transport belt
The transfer paper 17 and the transfer paper supported thereon are reversed and run at a speed VR (> VF) in the direction of the right arrow in FIG. At this time, the distance traveled by the belt 17 at time t ₁ + t ₂ can be quickly returned at time t ₃ . At the time of this return, the transfer paper trailing end is separated from the transfer paper transport belt 17 and advances to the upper surface of the paper trailing end guide plate 28, and this transfer paper moves accurately by a predetermined distance indicated by reference numeral 33 (paper leading end). Is at the position of the RT point)
And stops and waits for a time t ₄ (see FIG. 2 (j)) in preparation for the next M image transfer.

On the other hand, in the case of the PC belt 1, the formation process of the M image of the second color has already been performed even during the transfer of the Y image of the first color.
That is, the writing unit 5 based on the M image data
The formation of the electrostatic latent image of the optical writing by the control / drive is started when the PC drive roller 2 has rotated an integer number of times from the start of the Y image writing, in the example shown in FIG. ), (G)). The developing device is Y
The Y developing device 7 was in contact with and driven only in the image area, but before the second color M image area arrived, the Y developing device 7 was separated from the PC belt 1 and stopped (FIG. 2 ( m)), instead of this, the developing roller 8 of the M developing device 9 is brought into contact with and driven by the surface of the PC belt 1 (see FIG. 2 (n)) to prepare for visualization of the M image.

Then, when the leading end of the M image reaches the TS point, the PC drive roller 2 starts moving from the M image data writing start timing.
Motor transfer driving at the time that the number of pulses P ₀ corresponded rotational movement of the rotary component and PC drive motor encoder 37 forward start signal S
₂ (see FIG. 2 (h)) is input to the control drive circuit 43. Simultaneously or slightly later, the belt contact / separation switching roller 20 is moved to the upper position and presses the transfer paper transport belt 17, and the transfer paper transport belt is moved before the leading end of the transfer paper reaches at least the point T.
17 is brought into contact with the PC belt 1.

Well, the time from the timing of the forward start signal S ₂ signal
PC belt 1 at t _1, as in the case of the previous Y image, P ₁ is the number of pulses of the PC drive motor encoder (PC) 37, PC belt 1
The moving distance of has become a l _1. Sodoe, during also the time t ₁ towards the transfer paper, the state of the speed O VF during which time with rises (= VR) in the same PT ₁ as the number of pulses from the timing S ₁ of first color at time t ₁ In this case as well, position control is performed such that P ₁ = PT ₁ and both coincide with each other.
Accordingly, the leading end of the transfer paper has moved by the distance l ₁ at time t ₁ , and the Y image of the first color and the M image of the second color are aligned on the transfer paper.

Thereafter, the same process as described above is repeated for each color,
Finally, the process proceeds to the process following the writing of the Bk image data.

In the Bk image transfer process, the paper path switching guide plate 26 is moved to the dashed line position in FIG. 1, and the transfer paper during the transfer process is transferred from the leading end thereof by the transfer paper separating and discharging unit 24 while the transfer paper is discharged. It is separated from the transport belt 17 and transported toward the fixing device 31. Then, when the transfer of the Bk image, which is the last step, is completed, the transfer drive motor 39 continues the forward rotation and conveys the transfer paper (FIGS. 2 (j), (u),
(V), (y)). The transfer paper on which the toner image has been fixed by the fixing roller pair 31a of the fixing device 31 is discharged onto a discharge tray 32 as a color print. At this time, the transfer paper conveying belt 17 is applied with a charge removing corona from the timing when the rear end of the image area of the first copy has passed the charge remover 22, and is uniformly discharged. When the final copy is discharged, the motors, the fixing device, and the paper feed system are stopped.

Here, as shown in FIG. 2, when the repeat operation is performed, after writing the first Bk image data, the process proceeds to the Y image data writing process of the second sheet, and the operation control of the transfer paper transport belt 17 is performed. Also, the same operation as the first one is repeated. After the transfer, the residual toner is removed from the PC belt 1 by the cleaner 29, the residual charge is removed by the charge remover 30, and the PC belt 1 travels to the charger 4. Finally, the last color print is discharged to the paper output tray 32 and the PC belt 1
Then, the operation is stopped after the transfer paper transport belt 17 is cleaned and neutralized, and returns to the initial state.

The above description is based on the order of image formation and Y image → M image → C
Image ⇒ Bk image, and the arrangement of developing units is Y,
Although M, C, and Bk are used, the present invention is not limited to this.

Also, a method of optically writing an electrostatic latent image of each color with an LD or the like using digital image-processed image data of each color has been described. However, an analog optical image of a normal electronic copying machine is exposed at a predetermined timing at an exposure position E. Irradiation and image formation may be performed to perform color recording.

Further, the above description is about full-color printing by superimposing four colors. However, when two or three of these colors are superimposed, image formation and transfer of necessary colors are performed twice or three times.
After the rotation is continued, the recording operation may be terminated, and the operation control is performed in such a manner.

In the case of single-color image recording, the developing unit for that color is brought into contact with and driven by the PC belt 1 until the predetermined number of sheets is completed, and the transfer paper transport belt 17 is kept in contact with the PC belt. In this case, the paper path switching guide plate 26 guides the transfer paper toward the fixing device 31 while being held at the dashed line position in FIG.
Therefore, in the repeat recording, the print creation speed is 4/3 times higher in the case of three colors, twice as high in the case of two colors, and four times in the case of single color as compared with the case of recording four colors.
Further, the color of the developer is not limited to the four colors described above, and it is also possible to use blue, green, red and other desired colors in combination as needed.

The basic configuration and the copying operation of the color recording apparatus have been described above with reference to FIGS. 1 to 3.
In the configuration shown in FIG. 1, the transfer paper separating static eliminator 24 for separating the transfer paper after the final color transfer from the transfer paper transport belt 17 is used.
Is disposed at the position of the drive roller 18 for driving the transfer paper transport belt that supports the most downstream end side of the transfer paper transport belt 17.

However, when the transfer paper separating static eliminator 24 is arranged near the driving roller 18 for driving the transfer paper transport belt 17, the same problem as in the recording apparatus shown in the related art occurs.

That is, in the color recording apparatus having the above configuration, when the transfer paper size is larger than the belt length from the transfer position to the drive roller 18 or the driven roller 19, the transfer paper transport belt 17 moves forward in the transfer process before the final color transfer process. In motion
The leading edge of the transfer paper is separated from the transfer paper transport belt 17 at the portion corresponding to the drive roller 18 and advances to the paper leading edge guide plate 27, and at the time of backward movement, the rear end of the transfer paper is separated from the transfer paper transport belt 17 at the portion corresponding to the driven roller 19. The transfer paper transport belt 17 is configured to reciprocate so as to separate and advance to the paper trailing end guide plate 28. In such a case, the corona application by the transfer corona charger 21 is performed twice according to the number of transfers. When the electrostatic attraction between the transfer paper and the conveyor belt 17 becomes very strong as the transfer paper is repeated three times, the leading and trailing ends of the transfer paper are
In some cases, the sheet cannot be separated from the sheet 17 and is caught in the container, resulting in defective conveyance. Therefore, in order to prevent this, not only at the time of transfer paper separation and discharge at the end of the final color transfer process, but also at the time of reciprocation of other transfer processes, the transfer / separation static eliminator 24 is operated to facilitate separation of the transfer paper. There is a method,
At the position where the transfer / separation neutralizer 24 is arranged as shown in FIG. 1, the transfer paper is only neutralized from the leading end to the position of the separation neutralizer 24. As a result, the charging potentials of the transfer paper and the transfer paper transport belt 17 are different, and the transfer efficiency during the next transfer process differs between the above-described static elimination area and the area up to the rear end of the paper, causing unevenness in the transferred image. Problem arises.

Further, in the above method, since the trailing edge of the paper is not discharged at all, there is also a problem that there is no effect on the conveyance failure at the time of returning.

Therefore, in the present invention, in the color recording apparatus having the structure shown in FIG. 1, as shown in FIG. 4, the transfer paper separating and discharging unit 24 is positioned at the position indicated by reference numeral 24 'near the downstream side of the image transfer position. Or a counter electrode is provided together, or a transfer paper static eliminator 2 is provided separately near the downstream side of the image transfer position.
4 'and the counter electrode 44 are provided. During the transfer process, until the rear end of the transfer paper passes through the neutralization area by the transfer paper neutralizer 24 ', that is, until the rear end of the transfer paper comes to the downstream end of the opening of the neutralizer 24' (see FIG. 4). The transfer paper transport belt 17 is moved forward by a distance of l ₂ ′ from the transfer position). Then, after that, a reverse rotation start signal is given to the drive motor 39 of the transfer paper transport belt 17, so that the drive roller 18 is rotated reversely, and the transfer paper transport belt 17 is moved backward.

With such a configuration, the transfer paper static eliminator 24 ′
Is applied to the entire area of the transfer paper.

Then, in addition to the above configuration, the operation during the transfer process is changed as shown in the timing chart of FIG. That is, in addition to the charge removal of the transfer paper for transfer separation performed during the forward movement of the final color transfer process, at least
Even during the forward movement of the transfer process more than once, the transfer paper charge eliminator 24 'removes electricity from the entire transfer paper (see FIG. 5 (y)).

Therefore, in the color recording apparatus having the configuration shown in FIG. 4, the transfer paper static eliminator 2 is located near the downstream side of the transfer position.
4 'is provided, and during the transfer process, the transfer paper transport belt 17 is moved until the rear end of the transfer paper passes through the charge removal area by the transfer paper discharger 24'.
, And then the transfer paper transport belt 17 is moved backward, and the transfer paper transport belt for the transfer paper is used in addition to the transfer paper removal for transfer paper separation performed during the forward travel of the final color transfer process. In order to prevent transient electrostatic attraction to 17, the transfer paper static eliminator 24 'performs the transfer paper static elimination even during the forward movement of at least one transfer stroke before the final color transfer stroke. Even during the reciprocating movement of the transfer paper transport belt 17 during the transfer process prior to the final color transfer, it is possible to uniformly remove the charge from the leading edge to the trailing edge of the transfer paper, preventing the occurrence of charging unevenness during transfer, Further, transient electrostatic attraction of the transfer paper to the transfer paper transport belt 17 is prevented, and transfer failure of the transfer paper is almost completely prevented.

The only difference between the timing chart shown in FIG. 5 and the timing chart shown in FIG. 2 is the charge removal timing by the transfer paper separating corona indicated by the reference character y in each chart, and the other parts are the same. is there.

FIG. 5 shows a case where the charge is removed by the transfer paper separation corona in all the transfer paper movements during the transfer process for each color separation. However, this charge removal is not necessarily performed every time. Other than during the color transfer process (in the illustrated example, the Bk image transfer process), it may be performed once or more as needed.

In other words, the charge removal after the final color transfer is performed to completely separate the transfer paper from the transfer paper transport belt 17,
Since the static elimination during the other transfer steps is performed to prevent the transfer paper from being transiently electrostatically attracted to the transfer paper transport belt 17 and to prevent poor transport, the static attraction force is relatively low. In the first transfer process (Y image transfer in the figure) in which the transfer paper is considered to be weak, it is not always necessary to remove electricity from the transfer paper. Therefore, during the charge elimination other than during the final process, the electrostatic discharge between the transfer paper and the transfer paper transport belt 17 is considered to be strong during the second and subsequent transfer processes (C transfer,
That is, it may be performed once or more as needed in the M transfer process).

(Effects of the Invention) As described above, in the color recording apparatus according to the present invention, even when the transfer paper moves forward during a transfer process other than the final color transfer process, the entire transfer paper is discharged as necessary. With this configuration, it is possible to prevent the transfer unevenness of the superimposed image from occurring, and to prevent the transient electrostatic attraction between the transfer paper and the transfer paper transport body during each transfer process, thereby preventing transfer paper transport failure. Is prevented.

Therefore, according to the present invention, even when a color image is obtained by repeating transfer a plurality of times, a uniform transfer image can be obtained over the entire surface of the transfer paper, and the transfer failure of the transfer paper can be prevented. Can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a color recording apparatus suitable for carrying out the present invention, FIG. 2 is a timing chart showing basic operations of the color recording apparatus, and FIG. FIG. 4 is a perspective view including a block diagram showing a control system, FIG. 4 is a schematic main configuration diagram of a color printing apparatus when the present invention is applied to the color printing apparatus having the configuration shown in FIG. 1,
FIG. 5 is a timing chart showing an operation example of the above color recording apparatus. 1 photoreceptor 2 photoreceptor drive roller 5 optical writing unit 7,9,11,13 developing units for each color 14,3
3, 34 transfer paper, 17 transfer paper transport belt, 18 transfer roller transport belt drive roller, 24 'transfer paper static eliminator, 31
... Fixing device, 35 ... Color image reading device, 36 ... Photoconductor drive motor, 37,40 ... Encoder, 39 ... Transfer drive motor for driving transfer paper transport belt, 41 ... Main control circuit, 42 ... ... servo control drive circuit for photoconductor drive motor, 43
... Servo control drive circuit for transfer drive motor.

Claims (1)

(57) [Claims] An electrostatic latent image forming step of forming an electrostatic latent image corresponding to each color on a photosensitive member rotated at a constant speed for each color separation; and forming the electrostatic latent image using a developer corresponding to each color. A developing step of visualizing a latent image formed on the photoreceptor for each decomposition,
The transfer process of transferring the visualized image for each color separation onto transfer paper conveyed to a predetermined transfer position by a transfer paper conveyer capable of reciprocating operation and stop operation is sequentially repeated. The transfer paper is reciprocated a plurality of times to transfer the image for each color separation on the photoreceptor in an overlapping manner, and after the final color transfer is completed, the transfer paper is conveyed to a fixing device, and the image transferred to the transfer paper is transferred. In the color recording apparatus which obtains a color image by fixing the transfer paper, the transfer paper transporting body is a belt-like member stretched over a driving roller and a driven roller, and is determined by a belt length from a transfer position to a driving roller or a driven roller. When the size of the transfer paper is large, the leading edge of the transfer paper is separated from the transfer paper transport body by the drive roller-equivalent portion at the forward movement of the transfer paper transport body in the transfer process before the final color transfer process, and is transferred to the paper leading edge guide portion. Progress and return When the transfer paper is moved, the transfer paper transport body is reciprocated so that the rear end of the transfer paper is separated from the transfer paper transport body at a portion corresponding to a driven roller and proceeds to a paper rear end guide section, and A transfer paper discharger is provided near the downstream side, and during the transfer process, the transfer paper transporter is moved forward until the rear end of the transfer paper passes through the neutralization area by the transfer paper discharger, and then the transfer paper transporter is moved back. In addition to the above structure, the final color transfer process is performed in order to prevent excessive electrostatic attraction of the transfer paper to the transfer paper transport body in addition to the transfer paper discharging for transfer paper separation performed during the forward movement of the final color transfer process. A color recording apparatus characterized in that the transfer sheet static eliminator performs the transfer sheet static elimination even during the forward movement of at least one or more transfer steps.