JP2682634B2 - Color recording device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a transfer paper that reciprocates a toner image of a different color with respect to a color separation image sequentially formed on one image carrier at a transfer position to and from the image carrier. The present invention relates to a color recording device that transfers images by superposing them on a transfer paper carried and carried by a supporting and carrying means.

As a conventional color copying machine or color printer, for example,
As shown in the figure, the photosensitive belt 1 that rotates in one direction,
A charger 4, an image exposure device 5, and a plurality of developing devices 7, 9, 11, which are switchably operable and have different colors, which are arranged along the circumference thereof in the order of the circumferential direction. It has a transfer charger 21, a cleaner 29, and a static eliminator 30, and can be brought into and out of contact with the photoconductor belt 1 at the transfer position by the transfer charger 21, and electrostatically adsorbs the transfer paper fed from the paper feed unit 14. Transfer belt 17 that can be carried and reciprocated, and transfer belt 17
Of the transfer belt 17
During the forward movement, the toner is brought into contact with the photosensitive belt 1 to transfer a plurality of toner images successively formed on the photosensitive belt 1 by the above-mentioned process means one by one, and after transferring one image, the transfer belt After separating 17 from the photoconductor belt 1 and moving it back, the transfer paper is returned, the toner images of a plurality of predetermined colors are superposed and transferred on the transfer paper, and then the transfer belt 17 is moved forward to fix the transfer paper 31. There is known a color recording apparatus of a color separation image superposition transfer system in which a color separation image is transferred to a recording medium and fixed at one time to form a color copy.

The example shown in FIG. 5 is a movable color plate copier, in which the color platen 50 at the time of exposure places a color document and reciprocates in the direction opposite to the transfer belt 17, and 3 times for each forward motion. The color separation filters of the colors are switched and inserted, and the color separation images of the three colors are exposed.
The photosensitive member 1 is sequentially exposed to light via 3 to form three types of latent images.

In this apparatus, the photoconductor belt 1, the transfer belt 17 and the document table 50 are synchronized with each other at a predetermined speed, and the photoconductor belt 1
Is required to reciprocate in one direction, and the transfer belt 17 and the document table 50 are required to reciprocate in opposite directions.

FIG. 6 shows an example of the drive device previously proposed by one of the inventors of the present invention. The photosensitive belt 1, the transfer belt 17 and the platen 50 are driven by a single drive motor 52 so that the clutches 53, 5 are provided.
4, 55 and the gear train and belt transmission means shown in the figure,
It is adapted to be driven in a predetermined direction at a predetermined speed. Therefore, the photoconductor belt 1, the transfer belt 17 and the document table 50 are driven in perfect synchronization with high accuracy in a predetermined direction at a predetermined speed, and a color copy free from color misregistration and jitter can be obtained.

This method is applied to a color recording device that creates a color copy by directly exposing the photoconductor with a color-separated light image of a color original and developing it with toner of different colors to transfer the resulting toner images. Is an extremely excellent one in that only one driving source is required, and the three moving members can be moved in perfect synchronization so that the toner images of the respective colors are superposed with each other with high accuracy and no color shift occurs. , A laser, LED, LCD, or other light-inducing element is used to create a latent image by writing on the photoconductor with a light beam that is reduced by the image information signal of the color-separated image of each color. In consideration of the fact that the synchronous movement mechanism of the document table, which is required in the above-mentioned color copying machine, is not necessary in the recording apparatus, it is more suitable to provide the drive sources for the photoconductor and the transfer belt separately. it is conceivable that.

However, when the photoconductor belt and the transfer belt are driven by separate driving sources, even if the servo drive control is performed, the respective speeds slightly change due to load fluctuations, and the speed difference between the photoconductor belt and the transfer belt is different. Causes a sitter. Therefore, it is necessary to suppress load fluctuations as much as possible.

As described above, in the symmetrical color recording apparatus of the present invention, the transfer belt can be brought into contact with and separated from the photoconductor belt, and the transfer paper on which a toner image of a certain color has been transferred is separated from the photoconductor belt. After being placed on the transfer belt and returned, the transfer paper is conveyed at a timing such that the leading edge position of the image and the leading edge position of the transfer sheet are matched at the transfer section for the transfer of the toner image of the next color. The transfer belt must be driven so as to come into contact with the photosensitive belt by the time the leading edge reaches the transfer portion. In that case, for example, when the photoconductor belt is driven at a constant speed and the transfer charger is turned on, the transfer belt and the photoconductor belt are attracted by a strong force. At this time, if the transfer belt comes into contact with the photosensitive belt at a speed lower than that of the photosensitive belt, the photosensitive belt is loaded in the decelerating direction and the transfer belt is loaded in the accelerating direction. When the color-separated toner images are superposed in such a state, a resister having a positional deviation (color misregistration) at an overlapping portion is generated. Especially in the overlapped line drawing part, the color will be different from the original. Further, when slip occurs between the photoconductor belt and the transfer belt due to the difference in speed between the photoconductor belt and the transfer belt, the photoconductor belt is gradually damaged and the life is shortened.

Further, in the case where the toner images of three colors or four colors are superposed and transferred, even if the speeds of the photoconductor belt and the transfer belt can be matched at the time of transferring the individual colors, the transfer speeds of the three or four colors and When the positional relationship between the transfer belt and the photoconductor belt changes, the superimposed toner images of a plurality of colors are not accurately overlapped with each other, and different colors are reproduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned actual situation of the conventional color recording system of the above system in which the image carrier and the transfer paper supporting and conveying means capable of coming into contact with and separating from the image carrier are separately driven. It is possible to suppress the occurrence of jitter due to the load fluctuation applied to the supporting and conveying means, eliminate the positional deviation of the toner images of plural colors that are superposed, and also to prevent the friction caused by the speed difference between the image carrier and the transfer paper supporting and conveying means. Therefore, it is an object of the present invention to provide a color recording device in which the image carrier is prevented from being damaged and the life of the image carrier is shortened.

In order to achieve the above-mentioned object, the present invention provides the above-mentioned color recording apparatus in which the speed of the transfer material is the same as the speed of the image carrier, and the two are brought into contact with or separated from each other so as to bring them into contact with each other. It is characterized in that the means is driven.

Further, when transferring the toner images of the first color of the toner images of a plurality of colors, the transfer material is moved to the transfer step while moving forward, and after the transfer is completed, the transfer material is moved back and temporarily stopped and waits for the second color. Thereafter, the forward movement is started from this state by a timing signal from a predetermined position of the image carrier, and the transfer material and the image carrier are conveyed before the image leading edge position and the image leading edge position on the transfer material reach the transfer position. It is necessary to prevent the positional deviation of the superposed image from being controlled so that the forward movement speed and the positional relationship between the two are the same as the first color.

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

FIG. 1 is an overall configuration diagram of a color recording apparatus according to the present invention, FIG. 2 is an example of a timing chart of its basic operation, and FIG. 3 is a drive control block diagram thereof.

Note that FIG. 2 is divided into two parts (a) and (b) in relation to the drawing sheet.

 The configuration and operation will be described below based on these.

When the print switch is turned on (a in FIG. 2), the photoconductor belt 1 rotates the PC drive roller 2 clockwise by the PC (photoconductor) drive motor 36 and rotates at the linear velocity VP in the arrow direction. To do.

At the same time, the transfer driving motor 39 of the transfer paper conveying belt 17 (hereinafter, abbreviated as transfer belt) first starts forward rotation (see g and h signals in FIG. 2 and the velocity diagram of j), and then left. It rotates at the linear velocity of VF in the direction of the arrow. In addition, it is controlled and driven to rotate under the condition of VP = VF.

By the way, the photosensitive belt 1 (hereinafter abbreviated as PC belt) is
The charge is removed by the charge remover 30 and the entire surface of the charger 4 is uniformly charged, but the following conditions are met.

1. The static eliminator irradiates the surface of the PC belt from which toner has been removed by a PC cleaning device with light or applies a static elimination corona to bring the surface potential of the PC belt to approximately OV.

2. In the case of the negative-positive process, the toner adheres to the non-charged portion of the surface of the photoconductor, so the entire surface of the PC belt must be uniformly charged by the charger.

3. The charger performs uniform charging by corona discharge, but discharges a slight amount of ozone. This ozone decomposes in a short time when the discharge is stopped, but it may adversely affect the surface of the PC belt and impair the sharpness of the image. Therefore,
Air is sent from behind the charger (not shown) by a fan or the like, or sucked to eliminate the influence of ozone.

By the way, the rotation detection sensor 38 is attached to the shaft of the PC drive roller 2.
Is installed, and a detection pulse can be generated for each rotation of the roller. (B in FIG. 2) In the example in FIG. 2, the semiconductor laser (hereinafter abbreviated as LD) of the optical writing unit is started to be controlled and driven at the timing of the third pulse of this one rotation detection sensor, Let's take the LD example as an example, but you can use other types of lasers or LED arrays, L
Other optical writing unit such as CD array may be used)
Optical writing based on the Y image data is started to form an electrostatic latent image.

This image data is read by the color image reading device 35 installed at the upper part of FIG. 1, for example, into each of three color separation lights of blue, green and red, and image calculation is performed based on the intensity level of each color light. Processing is performed to obtain writing image data for each color of yellow, magenta, cyan, and black (hereinafter referred to as Y, M, C, and BK).

Apart from this, it may be image data output from another color image processing system (for example, a color facsimile, a word processor, a personal computer, etc.). The connection interface for that purpose may be individually supported.

By the way, the developing devices 7, 9, 11 for visualizing the electrostatic latent image,
13 is normally located at a position where the developing rollers 6, 8, 10 and 12 do not contact the PC belt surface.

Then, only before the latent image surface of the corresponding color reaches the developing roller position of each color until immediately after transmission, the developing device of the corresponding color is pressed in the left direction in FIG. Is set to a position where a predetermined amount of contact is achieved.

At the same time, in order to give the developing function only to the developing device, the driving of the developing roller and the portion that contributes to the development are started. (M to p in FIG. 2) First, since the latent image of the Y image is formed, the Y developing device 7 is brought into contact with and driven by the photosensitive member surface at a timing with respect to the latent image (FIG. 2). M) and visualize the Y image.

Next, in the transfer step, the transfer belt 17 is switched by the solenoid between the upper and lower positions of the roller 20 so that the transfer belt (PC drive roller portion) comes into contact with and separates from the PC belt surface.

First, when the printing operation starts, the transfer belt 17 is driven in the left arrow direction as described above, and then the transfer belt contact / separation switching roller 20 is pressed to the upper position to transfer the transfer belt.
17 is brought into contact with the PC belt 1. (T in FIG. 2) Then, the transfer paper 14 is fed at a predetermined timing to the paper feed roller 15
Then, the sheet is fed by the registration roller 16 at a timing so as to match the image position formed on the PC belt surface.

The transferred transfer paper 14 is corona-charged with a predetermined polarity by the paper adsorption charger 23 (x in FIG. 2) to be in close contact with the transfer belt so that the paper position does not shift during transfer. The above-mentioned transfer belt contact / separation switching roller 20 is also used as the counter electrode of the paper adsorption / charging device 23 to simplify the apparatus. It should be noted that the charge elimination of the transfer belt is performed by the charge elimination corona 22 before the first color transfer process. (W in FIG. 2) At this time, the transfer belt cleaner 25 is also performing cleaning processing.

Now, when the visualized Y image front end reaches a point Ts which is a predetermined distance from the transfer position T, a transfer drive motor forward rotation start signal S ₁ (h in FIG. 2) is sent to the control drive circuit of the transfer motor 39. Enter in 43.

However, at the time of S ₁ , the transfer drive motor 39 is already in the normal rotation, and the normal rotation operation is continued. (J in Fig. 2)
The timing of S ₁ is substantially the time when the front end of the transfer paper reaches the RT point, that is, the position in the front direction l ₁ of the transfer position T point, and the Y image front end of the PC belt also moves in the front direction of the T point. l ₁
It is the time when the position Ts point is reached.

In the example of FIG. 2, this is the time when the PC drive roller rotates four times from the Y image data writing start timing, and further, the number corresponding to the encoder pulse number P ₀ of the PC drive motor rotates. (D, e, f, h in Fig. 2) During this time, the PC belt starts from point E (image writing position)
It has moved by the distance to Ts point.

After a lapse of time t ₁ from the time point S ₁ , both the Y image front end and the transfer paper front end move a distance of l ₁ to reach the transfer position T point, and thereafter, the Y image transfer is performed by the transfer corona charger 21. Done.

PC drive motor encoder (PC) 37 at time t ₁ at this time
The pulse number of (FIG. 3) is P ₁ , and the pulse number of the transfer drive motor encoder (T) 40 (FIG. 3) is PT ₁ . (E, k in FIG. 2) Here, as the resolution of both encoders, if the belt moving dimensions per pulse are the same, P ₁ = PT ₁ and the ratio of the two is If α, P ₁ and PT ₁ are values corresponding to the coefficient α.

In this example, the condition of P ₁ = PT ₁ will be described below.

Now, as the Y image transfer process progresses, the front end of the transfer paper is separated from the transfer belt, passes through the solid line position of the transfer paper path switching member 36, and advances toward the paper front end guide plate 27.

Then proceeding further Y image transfer process, the transfer sheet trailing edge, the time point of passing through the distance l ₂ min, i.e., the transfer sheet from the S ₁ point, l ₁ + l _p (transfer sheet size) + l ₂ When moving the distance (time t ₁ + t ₂ ) (at this time, the transfer paper is in the position of the chain double-dashed line 34).
Reverse the motor. (I, j in FIG. 2) Prior to this reverse rotation, the transfer belt contact / separation switching roller
20 is lowered to the lower position, and the transfer belt 7 is separated from the surface of the belt 1.

The reverse rotation causes the transfer belt and transfer paper to VR in the direction of the right arrow.
Make a quick return at a speed of (> VF). At this time
In the short return time of t ₃ , the distance equal to the distance moved to the left by t ₁ + t ₂ is position-controlled to the right to recover and stop.

At the time of this return, the trailing edge of the transfer paper is separated from the transfer belt and advances toward the paper trailing edge guide plate 28. Then, exactly after returning a predetermined distance, the transfer paper stops at the two-dot chain line state position of 33 (the paper front end position is the RT point position) and waits for the transfer of the M image of the second color (time t ₄ ). And

On the other hand, in the case of the PC belt 1, even during the transfer of the Y image of the first color, the formation of the M image of the second color has already been completed when the PC drive roller rotates an integral number of times from the start of writing the Y image. In the case of, it has started at the time of rotating four times.

The developing device contacts the Y developing device only in the Y image area.
Before the second image M area is driven, the Y imager 7 is separated from the PC belt surface and the driving is stopped.

Instead, the M developing device 8 is
Before the tip of the M image area reaches, it is brought into contact with and driven by the PC belt surface (n in FIG. 2) to visualize only the M image latent image area into the M image.

Next, when the leading edge of the M image reaches the Ts point, that is, as in the case of the first color, four rotations of the PC drive roller and rotations corresponding to the number of pulses P ₀ of the PC drive motor encoder are moved from the M image data writing start timing. Then, the transfer drive motor forward rotation start signal S ₂ is input to the control drive circuit 43. This causes the transfer belt 17 to start moving leftward.

At the same time as this, or with a slight delay, the contact / separation signal (t in FIG. 2).
Transfer roller contact / separation switching roller 20 by solenoid 44
Are contacted in the upward position direction at least until the pressing operation is started and the leading edge of the transfer paper reaches point T. In that case, as shown in FIG. 4, the transfer belt and the PC belt 1 come into contact with each other after the speed becomes equal to the transfer belt speed Vp. That is, the switching roller 20 is driven so that the gap becomes zero.

Now, at the time t ₁ from the timing of S ₂ , the PC belt 1 becomes the PC drive motor encoder (P
The number of pulses in C) is P ₁ , and the PC belt surface travel distance is l ₁ .

Therefore, the transfer paper also changed from the state of 0 speed during this t _1.
While launching to VF (= VP), the first color S ₁
To be the same PT ₁ as the number of pulses in the t ₁ hour from, performs the position control such Again is P ₁ = PT ₁ and both coincide.

As a result, the leading edge of the transfer paper also moves by l ₁ at t ₁ , and the Y image of the first color and the M image of the second color are aligned on the transfer paper.

After that, the same process as above is repeated. That is, M image transfer, transfer paper quick return, C image data writing, C development, C image transfer, transfer paper quick return BK
Proceed to development and BK image transfer.

 Next, description will be given after the BK image transfer.

At the BK image transfer step, the paper path switching guide plate 26
However, the transfer paper is switched to the position indicated by the alternate long and short dash line, and the transfer paper in the transfer process is transferred from the leading end toward the fixing device 31 while being discharged by the paper separation charger, and even if the trailing end of the transfer paper has finished transferring, the transfer drive continues. The motor continues forward rotation to convey the transfer paper to the left, and the fixed color print is delivered to the tray 32. (J, u, v, y in FIG. 2) At this time, the transfer belt 17 is uniformly discharged by applying a discharging corona from the timing when the trailing edge of the first image area passes through the discharging device 22. (W in FIG. 2) When performing the repeat operation as in the case of FIG.
After the second BK image data writing, as shown in FIG. 2, the process proceeds to the second Y image data writing, and the operation control of the transfer paper and the transfer belt also performs the same operation as the first operation.

After the transfer, the PC belt 1 is cleaned by the cleaner 29 to remove the residual toner, and further, the static eliminator 30 removes the residual charge, and proceeds toward the charger 4.

Finally, the last color print is conveyed to the tray 32, and after the PC belt 1 and the transfer belt 17 are cleaned and discharged, the operation is stopped and the initial state is restored.

In the above description, the image forming order is Y, M, C, and BK, but the order is not limited to this.

Further, the electrostatic latent image formation of each color has been described by a method in which each color image subjected to digital image processing is used to optically write with an LD or the like. However, an analog optical image of a normal electrophotographic copying machine is provided at a position E at a predetermined position. The same color recording can be performed by performing timing position control to form an image.

Up to this point, the description has been given of the four-color superposed recording of Y, M, C, and BK. However, in the case of these two-color or three-color superposed recording, the necessary image formation and transfer are continuously performed twice. Alternatively, the operation of each unit is controlled so that this is completed three times.

Also, in the case of single-color recording, the developing device for that color is driven and the transfer belt is kept in contact with the PC belt until the specified number of sheets are finished, and the paper path switching guide plate
Reference numeral 26 denotes a position where the transfer paper is guided in the direction of the fixing device 31 and is held and performs a recording operation.

Therefore, in the repeat recording, the print creation speed is 4/3 times for the three colors, twice for the two colors, and four times for the single colors in the repeat recording.

The developing colors are not limited to the above four colors, and it is also possible to use a desired color such as blue, green, red or the like in combination as required.

Effect As described above, according to the present invention, fluctuations in load applied to drive both the image carrier and the transfer sheet supporting and conveying means can be reduced, and the occurrence of jitter can be suppressed, and the image carrier due to the slip of both members. It is possible to prevent damage. Further, by matching the positional relationship during transfer of a plurality of toner images, it is possible to prevent the positional deviation of the toner images of the respective colors.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing the overall structure of an embodiment of the present invention, and FIG. 2 is a timing chart thereof for the sake of space (a),
(B) FIG. 3 is divided into two parts, FIG. 3 is a drive control block diagram of the photosensitive belt and the transfer belt, and FIG. 4 is an enlarged detailed view of a part of a timing chart. FIG. 5 is a side sectional view showing an example of the configuration proposed before of the color recording apparatus in which the photosensitive belt, the transfer belt and the document placing table are synchronously driven by one driving source, and FIG. FIG. 3 is a perspective view of the drive system. 1 ... Photosensitive belt (image carrier) 5 ... Optical writing means 7, 9, 11, 13 ... Developing means 17 ... Transfer belt (transfer paper support / conveying means) 20 ... Contact / separation switching roller (transfer) 21: Transfer charger 36: Photoconductor belt drive motor 39: Transfer belt drive motors 41-43: Control device

Front page continuation (72) Inventor Kazunori Sakauchi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company Ricoh (72) Inventor Kazushige Taguchi 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Company (56) Reference Japanese Patent Laid-Open No. 63-49769 (JP, A) Actually developed 61-126263 (JP, U)

Claims (2)

(57) [Claims] 1. An image carrier that rotates in one direction, an optical writing unit arranged along the image carrier, a developing unit for a plurality of colors that can be switched and operated, a transfer unit, and a transfer by the transfer unit. And a means for moving the transfer material to and from the image carrier at a position, a drive means for reciprocating the transfer material, and a drive means for driving the image carrier. One of the toner images of the respective colors sequentially formed on the image carrier is brought into contact with the carrier, and the transfer material is separated from the image carrier after the transfer of the toner image of one color is completed, and then the reciprocating motion is performed. In the color recording apparatus in which the transfer material is returned and the toner images of a plurality of different colors are superposed and transferred, both of them are contacted with each other after the speed of the transfer material becomes the same as the speed of the image carrier. It is characterized in that the above-mentioned contact and separation means is driven. And color recording device. 2. When a toner image of the first color is transferred, the transfer material is moved to the transfer step while moving forward, and after the transfer is completed, the transfer material is moved back to be temporarily stopped and waited. From the state, the forward movement is started by a timing signal from a predetermined position of the image carrier, and the forward movement of the transfer material and the image carrier is performed before the position corresponding to the image leading edge and the position corresponding to the image leading edge on the transfer material reach the transfer position. The color recording apparatus according to claim 1, wherein the speed and the positional relationship between the two are controlled to be the same as the first color.