JPH02304466A - Recording device for overlapped image - Google Patents

Abstract

PURPOSE:To restrain the influence on a charge carrier, etc. and developer consumption by setting the abnormality when the drive of the charge carrier does not match with the carriage of a recording sheet. CONSTITUTION:The device is provided with moving amount detecting means 2114 and 2116 which detect the moving amount on the periphery of the charge carrier 211, and a recording sheet is duplicately carried by a reciprocating means 231. Here, the abnormality is set when the moving amount of the periphery of the charge carrier 211 after the electrostatic latent image of an image to be transferred next time starts the formation and reaches the prescribed value before this recording sheet reaches the prescribed reciprocative carriage start position. Thus, the recording process is canceled when the abnormality is set by setting the abnormality when the drive of the charge carriage 211 does not match with the carriage of the recording sheet. Therefore, the influence on the charge carrier 211, etc. and the developer consumption can be restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an overlapping image recording apparatus for overlappingly recording a plurality of images on the same recording paper.

Magenta and cyan or yellow and magenta.

The present invention relates to a color image recording device that repeatedly records cyan and black color images.

■Conventional technology For example, in some color copying machines.

yellow, magenta and cyan or yellow.

Magenta, cyan, and black color toner images are transferred onto recording paper in duplicate. In other words, an electrostatic latent image corresponding to the yellow component of the original image is formed, developed with yellow toner, and transferred to recording paper. Next, an electrostatic latent image corresponding to the magenta component of the original image is formed. The image is then developed with magenta toner, the yellow toner image is superimposed on the recording paper, and an electrostatic latent image corresponding to the cyan component of the original image is formed and developed with cyan toner. The magenta toner image is superimposed and transferred onto the transferred recording paper. If black is included, a black toner image obtained by developing an electrostatic latent image corresponding to the black component of the original image with black toner is further superimposed and transferred on top of this. (
The order of each color is an example. ) An example of this type of copying device is disclosed in Japanese Patent Application Laid-Open No. 58-198062.
This can be found in Japanese Patent Application Laid-Open No. 62-118366, etc. The devices disclosed in these documents all have one transfer site, and make it possible to transfer a plurality of times by electrostatically adhering the recording paper to a reciprocating transfer belt and reciprocating the recording paper.

In this case, the formation start timing of the next electrostatic latent image and the backward conveyance speed of the recording paper are determined so that the recording paper is positioned at a predetermined forward movement start position before the next toner image moves to the transfer position. is set.

(2) Problems to be Solved by the Invention In this type of device, the transfer belt repeatedly moves forward, stops, and moves backward, so it is difficult to accurately manage its speed control. For this reason, a margin is provided in the timing settings to absorb some speed fluctuations, but if the drive system changes over time or is overloaded, this margin may not be able to absorb it. In particular, when performing back transport at high speed to shorten processing time, the fluctuation in the amount of movement of the recording paper due to speed fluctuations becomes large, and the return transport speed does not rise to the specified value due to overload, etc. An abnormality may also occur in which forward conveyance and transfer are started before the recording paper is positioned at a predetermined forward conveyance start position. Such an abnormality not only causes color shift in the recorded image but also causes damage to the photoreceptor.

SUMMARY OF THE INVENTION An object of the present invention is to detect an abnormality in the conveyance of a recording paper and to prevent it from affecting other components in an overlapping image recording apparatus that performs overlapping recording by reciprocating the recording paper.

0 Means to solve the problem In order to achieve the above object, the present invention has the following features: An electrostatic latent image corresponding to the original image is formed on the charge carrier.

A recording device that develops the image and transfers it onto recording paper, in which the recording paper is supported on a reciprocating means, and the reciprocating means is controlled to reciprocate the recording paper to perform overlapping recording. In an image recording apparatus: a movement amount detection means for detecting the movement amount of the circumferential surface of the charge carrier; when the recording paper is transported back by the reciprocating means, the recording paper reaches a predetermined forward transport start position. It is assumed that an abnormality is set when the amount of movement of the circumferential surface of the charge carrier after starting the formation of an electrostatic latent image of the image to be transferred next reaches a predetermined value.

(2) Effect According to this, an abnormality is set if the drive of the charge carrier and the conveyance of the recording paper are not aligned. If the recording process is stopped when an abnormality is set, the influence on the charge carrier and the like and the consumption of developer can be suppressed. Further, when an abnormality is set, the operability can be improved by stopping the recording process and ejecting the recording paper. In this case, if a recording paper guide means for receiving the recording paper that has come off the reciprocating means is provided, the recording paper may be ejected to the recording paper guide.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

(2) Embodiment FIG. 1 is a cross-sectional view showing an outline of the mechanism of a color copying apparatus embodying the present invention.

This device is mainly composed of an image scanner 1 and a color laser printer 2.

The components of the image scanner 1 are divided into an optical scanning system 11, a photoelectric conversion system 12, and an image processing system 13.

The optical scanning system 11 includes a contact glass 111°, an illumination lamp 112. It includes mirrors 113, 114, 115, a condensing lens 116, and a driving mechanism for these; here, it optically scans an original placed on a contact glass 111 and guides the reflected light to a photoelectric conversion system 12. .

The photoelectric conversion system 12 includes a color separation filter, a CCD array, etc., and here converts the light reflected from the document given by the optical scanning system 12 into a red (R) component, a green (G) component, and a blue (B) component. The signal is divided into 1 pixel and converted into an electrical signal.

The image processing system I3 is composed of hardware that controls each component and processes electrical signals.
Each color is yellow (Y) after R treatment (under color removal treatment), etc.

Magenta (M), cyan <C> and black (Bk)
Binarized data corresponding to (hereinafter referred to as Y data and M
data (referred to as C data or Bk data).

The components of the laser printer 2 are: 1 image forming system 21° paper feeding system 2
2. Transcription system 23. It is divided into a fixing paper discharge system 24 and a control system 25 (see FIGS. 2a and 2b).

The image forming system 21 includes a photoreceptor belt 211. Cleaning unit 212. Pj [unit 213. Obi ffi unit 214. A laser writing unit 215, a developing unit 216, and the like are included.

The photoreceptor belt 211 is stretched between a drive roller 2111 and a driven roller 2112 (hereinafter these rollers are referred to as a PC drive roller or a PC driven roller), and is cleaned by a press roller 2113 provided opposite to the cleaning unit 212. unit 2
Pressure is applied to the 12 side. Referring to FIG. 2b, a one-rotation pulse generator 2114 and a motor with an encoder (hereinafter, the motor side will be referred to as a PC drive motor 2115 and the encoder side will be referred to as an encoder 2116) are connected to the roller shaft of the PC drive roller 2111. has been done. The photoreceptor belt 211
Drive motor 2115 drives arrow VP force direction linear velocity V
is driven by.

The cleaning unit 212 wipes the surface of the photoreceptor belt 211 to remove adherents such as toner, and the static eliminating unit 213 applies a static eliminating corona to the surface to eliminate static, and the potential is approximately Ov. Further, the charging unit 214
Photoreceptor belt 211 after cleaning and static elimination
A charged corona is applied to the surface of the material to uniformly charge it. In addition,
A suction fan with an ozone filter is provided near the static eliminating unit 213 and the charging unit 214 in order to prevent the atmosphere from becoming ozonated due to corona discharge.

The laser writing unit 215 writes Y data, M data, C data, or Bk data given from the image scanner l.
Based on the data, the laser beam is modulated on/off and irradiated onto the photoreceptor belt 211 to form an electrostatic latent image.

The developing unit 216 includes a Y developer 216y containing yellow toner and an M developer 216i+ containing magenta toner.
, a Cm image quantity unit 216c containing cyan toner, and a Bk developing unit 216b containing black toner. Each developing device 216y, 216m, 216c and 216b has a developing roller 2161y, 2161m, 2161, respectively.
c and 2161b. Each developing roller 216
1y, 2161m, 2161c, and 2161b are each supported by groove-shaped bearings extending obliquely upward toward the photoreceptor belt 211, and when at rest, they fall to the lower end due to their own weight and are separated from the photoreceptor belt 211. When it is urged to rotate, it climbs the bearing and comes into contact with the photoreceptor belt 211. At this time, the toners of each color carried around the respective toners are attached to the electrostatic latent image on the photoreceptor belt 211.

The paper feed system 22 includes a paper feed cassette 221. Paper feed roller 222
, registration rollers 223, their drive mechanisms, and the like. The paper feed cassette 221 holds recording paper of a predetermined size, and the paper feed roller 0222 takes out the recording paper one by one from there.
The recording paper taken out by the transfer system 2 at a predetermined timing.
3.

The transfer system 23 includes a transfer belt 231. Static elimination unit 23
2. Cleaning unit 2331 Paper adsorption charging unit 234. Transfer unit 235. II.Charging unit 236, switching unit 237. A front end guide plate 238, a rear end guide plate 239, etc. are included.

The transfer belt 231 is stretched around a drive roller 2311 and a driven roller 2312 (hereinafter these rollers are referred to as a transfer drive roller and a transfer driven roller).
, now referring to FIG. 2b, transfer drive roller 2
The roller shaft of 311 has a motor with an encoder (
Hereinafter, the motor side will be referred to as a transfer drive motor 2315, and the encoder side will be referred to as a first encoder 2316).At the other end, there is a second encoder (not shown in the figure because it is hidden behind the photoreceptor belt 211, but it is referred to as a 2317). ) are connected to each other. The transfer belt 231 is driven by the transfer drive motor 2315 at a linear velocity V that is the same as the linear velocity of the photoreceptor belt 211 in the direction of arrow Vf force, and is driven at a linear velocity V' that is much faster than the linear velocity V in the direction of arrow Vr force. (Quick return method).

Normally, the transfer belt 231 is separated from the photoreceptor belt 211, but when a lift-up roller 2313 provided near the middle between the transfer drive roller 2311 and the transfer driven roller 2312 is driven upward by a solenoid (not shown), the transfer belt 231 is pushed up. It is raised and touches at the T point.

The static eliminating unit 232 applies a static eliminating corona to the surface of the transfer belt 231 to eliminate static electricity, and the cleaning unit 2
33 wipes the surface to remove deposits such as toner.

The paper attraction/charging unit 234 applies a charging corona to the surface of the transfer belt 231 to charge it, and causes the recording paper fed from the registration rollers 223 to be attracted to the transfer belt 231 .

Note that since this counter electrode is also used as the lift-up roller 2313, the device configuration is simplified.

The transfer unit 235 transfers the toner image on the photoreceptor belt 211 onto the recording paper by applying a transfer corona from inside to the recording paper on the transfer belt 231 at point T where the transfer belt 231 and the photoreceptor belt 211 come into contact. .

The charge removal/charging unit 23G functions as a static eliminator when an AC high voltage is applied, and functions as a charger when a DC high voltage is applied. In this embodiment, the recording paper is conveyed by the transfer belt 231. When moving under the lever removal/charging unit in the direction of the arrow Vf force, remove it tIi
It functions as a charger to facilitate separation of the recording paper and transfer belt 231, and when moving in the direction of arrow Vr force, it functions as a charger to increase the adhesion force between the recording paper and transfer belt 231.

Note that the transfer drive roller 2311 also serves as this counter electrode.

Since the switching unit 237 is normally located at the position indicated by the solid line,
The recording paper is guided to the leading edge guide plate 238, but when it is rotationally driven by a solenoid (not shown), it moves to the position indicated by the dashed line and guides the recording paper to the fixing paper discharge system 24.

The leading end guide plate 238 and the trailing end guide plate 239 receive the portion of the recording paper that has come off the transfer belt 231 due to the reciprocating motion.

The fixing paper discharge system 24 includes a fixing unit 241, a paper discharge tray 242, and the like. The fixing unit 241 is
Fixing roller 2411. Consisting of a paper ejection roller 2412 and a drive mechanism thereof, the recording paper sent from the transfer system is subjected to heat fixing processing and ejected to the paper ejection tray 242.

As shown in FIG. 2a, the control system 25 includes cPU, RA
M, ROM etc. (IF) Memo IJ, I10 interface, timer, counter, A/D converter.

Main control board 251 with a D/A converter and various ICs. Servo control board 252 that controls the PC drive motor 2115. A servo control board 253 that controls the transfer drive motor 2315. Operation and display board 254 operated by the operator. High voltage control board 255 that supplies high voltage to various parts. A fusing heater control board 256 that controls the fusing heater. Sensor group 2 including various sensors
57. It consists of an actuator group 258 including a motor, a clutch, and a solenoid that drive each part. Below, one of these elements that is closely related to the features of this embodiment will be explained.

FIG. 2b shows the PC drive motor 2 in the control system 25.
115 and a block diagram in which elements related to control of the transfer drive motor 2315 are extracted. Referring to this figure, the energizing line of the PC drive motor 2115 is connected to the servo control board 252, and the signal line of the rotary pulse generator 2114 coupled to the same shaft is connected to the main control board 251 and the servo control board. 253. Further, the signal line of the encoder 2116 integrated with the PC drive motor 2115 is connected to the main control board 251. It is connected to the servo control board 252 and the servo control board 253, and the energizing line of the transfer drive motor 2315 and the first encoder 2 integrated therewith.
316 and a second encoder 2317 signal line coupled to these same axes are connected to the servo control board 253.

The servo control board 252 controls the PC drive motor 0N10FF signal b (same meaning below 2 corresponding to the symbol attached to the timing chart in FIG. 4a) given from the main control board 251 to the H level.
The servo control board 253 drives the transfer drive motor 0N10F given from the main control board 251.
When the F signal g is at the H level and the forward rotation signal turns to the H level, the transfer drive motor 2315 is urged to rotate in the forward direction (the transfer belt 231 moves in the direction of the Vf force) from the rising edge, and the reverse rotation signal i goes to the H level. , the transfer drive motor 2315 is urged in the reverse direction (the transfer belt 231 moves in the direction of the Vr force) from the rising edge.

The high voltage control board 255 includes high voltage energizing units 2551 to 2556 and various bias setting units 2557y to 2558 that energize various charging and neutralizing units, among which a high voltage energizing unit for the static eliminating and charging unit 236 2551 is shown in FIG. This unit consists of a paper suction high voltage circuit 25511 and a paper suction high voltage circuit 25.
Consists of 512. Each circuit has a trigger circuit,
The former applies an AC high-voltage voltage to the charge removal/charging unit 236 when the main control board 251 gives a trigger for outputting paper static electricity removal, and makes it work as a static eliminator. When a trigger is given, a DC high voltage having the same polarity as that of the paper adsorption/charging unit 234 is applied to the charge removal/charging unit 236 to make it function as a charger.

The sensor group 257 includes a paper size sensor 2571 for detecting the size of recording paper in the 8-paper cassette 221, a paper end sensor 2572 for detecting the presence or absence of recording paper in the paper feed cassette 221, and a paper end sensor 2572 for detecting the presence or absence of recording paper in the paper feed cassette 221. A paper jam sensor 2573 for detecting paper feeding, a paper discharge jam sensor 2574 for detecting abnormal discharge of recording paper, and a transfer belt contact sensor for detecting contact/separation between the photoreceptor belt 211 and the transfer belt 231. A release sensor 2575, a registration sensor 2576 for detecting paper feed registration, and a paper quality sensor 2577 for detecting the paper quality of fed recording paper.
etc. are included. The main control board 251 controls each component in cooperation with the control device 110 of the scanner 1, the control device 1110 of the scanner 1, the control device of the laser writing unit 215, etc. while monitoring the status of each component using these sensors. Figures 4a to 4d are timing charts showing the main operations of this control and the various parts brought about by it.
Figures 4d show partial details).

First, please refer to Figures 4a and 4b.

When the print start key on the operation & display board 254 is operated and the print start signal a changes to H level, the main control board 251 activates the PC drive motor 0N1.
Converts the 0FF signal to H level and connects the servo control board 25.
2 to energize the PC drive motor 2115, transfer drive motor 0N10FF signal g to H level,
The normal rotation signal is changed to H level for a short period of time, S pulse is output, and the transfer drive motor 23 is transferred to the servo control board 253.
15 instructs normal rotation bias.

As a result, the servo control boards 252 and 253
The PC drive motor 2115 and the transfer drive motor 2315 are energized, respectively, and the PC drive motor 211 is energized.
5 drives the photoreceptor belt 211 in the direction of the arrow VP force, and the transfer drive motor 2315 drives the transfer belt 211 in the direction of the arrow Vf at a linear velocity V (see speed diagram C+1).
.

While the PC drive motor 2115 is energized, the rotation pulse generator 2114 rotates the PC drive roller 2111.
The encoder 2116 outputs one pulse every time the photoreceptor belt 211 moves by 10 μm. These become the rotation detection signal d and the PC encode signal e. Further, while the transfer drive motor 2315 is energized, the first encoder 2316 outputs one pulse for every 10 μm movement of the transfer belt 231, and the second encoder 2317 outputs one pulse for each 10 μm movement of the transfer belt 231.
Outputs 1 pulse for every 1 movement.

These become the first transcription encode signal and the second transcription encode signal 2.

When the number of pulses of the rotation detection signal d after the print start signal a reaches three, the surface of the photoreceptor belt 211, which has been cleaned, neutralized, and uniformly charged, reaches the writing position E of the laser writing unit 215. Therefore, the main control board 251 instructs the laser writing unit 215 to write an image using Y data (timing diagram f). The laser beam is modulated on/off and irradiated onto the surface of the photoreceptor belt 211 located at the writing position 1E to form an electrostatic latent image corresponding to Y data.

During this time, the transfer belt 231 is neutralized and cleaned (timing diagram x), and is pushed up toward the photoreceptor belt 211 by the lift-up roller 2313 (
Activation of the solenoid: Timing diagram u), and the paper feed roller 222 feeds out the first sheet of recording paper to the registration roller 223 (timing diagram r).

The main control board 251 activates the Y developer 216y at the timing when the leading edge of the electrostatic latent image corresponding to the Y data reaches the development position of the Y developer rjt 216y (timing diagram n). So, Y developer 2
Since the developing roller 2161y of 16y contacts the photoreceptor belt 211, an electrostatic latent image corresponding to the Y data is developed with the Y toner.

After that, the leading edge of this Y toner image is Q, which is just before the transfer position T.
When reaching the position a (12o is the distance from point T to the registration roller 223), the registration roller 223 is energized (timing diagram S), and the paper adsorption charging unit 234 (
Timing diagram y) is energized to transfer the recording paper to the transfer belt 23.
Let it adsorb to 1.

Furthermore, when the leading edge of the Y toner image reaches Q1 @Ts before the transfer position UT point, the main control board 251 changes the normal rotation signal to H level for a short time, outputs the S1 pulse, and attaches the transfer unit 235. (timing diagram t). This timing is from the start of image writing using Y data to 4 pulses of rotation detection signal d (PC drive roller 2111
4 rotations) plus the Po pulse of the PC encode signal e. Further, at this time, the leading edge of the recording paper is at position P, which is Q1 before the transfer position T point.

Note that, since the servo control board 253 has already energized the transfer drive motor 2315 for normal rotation, it continues to energize the transfer drive motor 2315 for normal rotation regardless of the arrival of this 81 pulse.

When time t1 elapses after outputting the S1 pulse, the leading edge of the Y toner image on the photoreceptor belt 211 and the leading edge of the recording paper reach the transfer position T point, and the transfer unit 235 performs the transfer. During this period, the number of pulses pp of the PC encode signal e output by the encoder 2116 and the number of pulses Pjl of the first transfer encode signal output by the first encoder 2316 become equal.

Thereafter, application of the paper charge removal corona output to the charge removal/charging unit 236 is started at the timing when the leading edge of the recording paper is directly below the charge removal/charging unit 236 (as indicated by the two-dot chain line in the timing diagram Z1 shown in FIG. 4b). As a result, the charge removal/charging unit 236 removes the charge from the recording paper, and the recording paper separates from the transfer belt 231 as the transfer progresses.
7 to guide the distal end guide plate 238. This static elimination is
When the recording paper is sent to the leading edge guide 238, it prevents the recording paper from coming into contact with the lower part of the fixing unit 241 due to electrostatic attraction. It becomes unnecessary when static electricity is removed by etc.

Further, the surface of the photoreceptor belt 211 after the transfer is cleaned in a cleaner unit 212 and neutralized in a static elimination unit 213, and then returned to the charging unit 211.
4, it is uniformly charged and moves toward the writing position E point.

During this time, the main control board 251 measures the timing when the rear end of the electrostatic latent image corresponding to the Y data passes the development position of the Y developer 216y, and de-energizes the Y developer 216y (timing diagram n). As a result, the developing roller 2161y of the Y developing device 216y separates from the surface of the photoreceptor belt 211.

In addition, the transfer unit 235 is deenergized at the timing when the transfer of the trailing edge of the recording paper is completed (timing diagram t),
The application of the paper charge removal corona output to the charge removal/charging unit 236 is stopped (timing diagram zt), and the solenoid of the lift-up roller 2313 is deenergized to separate the transfer belt 231 from the photoreceptor belt 211 (timing diagram u
).

Furthermore, when the trailing edge of the recording paper moves from the transfer position T to the position Q2, the reverse rotation signal i is briefly changed to the H level and R1
It outputs a pulse to instruct the servo control board 253 to reversely energize the transfer drive motor 2315, and also to
A paper adsorption corona output is applied to the charging unit 236 (timing diagram Z2 in FIG. 4b). If the length of the recording paper in the feeding direction is Qp, this timing is CQ1 + Q P + Q2 )/V time after the output of the S1 pulse, that is, after (t1 + t2) time, and at this time the recording paper is placed first. It is sent out to the box guide plate 238 side and 2 points l in Fig. 1! It is located at the position indicated by the 4 lines.

The transfer drive motor 2315 is energized in the reverse direction for a time t3, which is much shorter than the (tl+t2) time.
is driven at a linear velocity V' in the force direction of arrow Vr, and the recording paper is driven at (Qt
10ΩP+02) to the right. Therefore, the leading edge of the recording paper becomes point P again.

The rear end is guided by a rear end guide 239, as shown by the dashed line in FIG. 1, in preparation for transferring the second color M toner image.

In this reverse biasing, the recording paper is removed by the charging unit 23.
6, and is strongly re-adsorbed onto the transfer belt 231. Note that the application of the paper adsorption corona output to the leading edge of the recording paper is stopped at the timing when the leading edge of the recording paper passes under the charge removal/charging unit 236 (timing diagram 22).

On the other hand, after instructing the laser writing unit 215 to write an image using Y data, the main control board 251 outputs the fourth pulse of the rotation detection signal d (PC drive roller 2
111 (4 rotations), this time an instruction is given to write an image using M data (timing diagram f). This timing is
This timing is earlier than the transfer start timing of the Y toner image by the PO pulse of the PC encode signal e.

Similarly to the above, the M developing device 216m is energized at the timing when the leading edge of the electrostatic latent image corresponding to 1M data reaches the developing position of the M developing device 216m (timing diagram 0), and the M toner developed at this time is activated. When the leading edge of the image reaches transfer position 1 [Q1 position before point T] [Ts], the main control board 251 changes the forward rotation signal to H level for a short time and outputs the S2 pulse to energize the transfer unit 235. (Timing diagram t
). As a result, the servo control board 253 urges the transfer drive motor 2315 to rotate normally to increase the linear velocity of the transfer belt 211 in the arrow Vf force direction to ■.

Further, the main control board 251 energizes the solenoid of the lift-up roller 2313 substantially simultaneously with the output of the S2 pulse to push the transfer belt 231 toward the photoreceptor belt 211 (timing diagram U).

The timing at which the main control board 251 outputs 82 pulses is based on the start of image writing using M data, and as described above, the timing at which the main control board 251 outputs 82 pulses is 4 pulses of the rotation detection signal d (4 rotations of the PC drive roller 2111) plus the PC encode signal. This is after the Po pulse of e, and at this time, the leading edge of the recording paper is at position 1[P of Q1 before the transfer position T point. Therefore, when one hour t1 has passed after outputting the S2 pulse,
The leading edge of the M toner image on the photoreceptor belt 211 is at the transfer position T
Reach the point. In other words, since the number of pulses of the PC encode signal e output by the encoder 2116 during this period is Pp, position control is performed so that the number of pulses Ptl of the first transfer encode signal output by the first encoder 231G is equal to Pp. . Due to this.

11 hours after outputting the S2 pulse, the photoreceptor belt 2
The leading edge of the M toner image on 11 and the leading edge of the recording paper are at the transfer position l.
They match at point T, and the transfer unit 235 starts transferring the M toner image.

Thereafter, the above steps are repeated to form and transfer a C toner image and a Bk toner image.

After the transfer of the Bk toner image starts, the main control board 251 energizes the solenoid of the switching unit 237 to record the image.
The paper conveyance path is switched to the fixing unit 241 side, and a paper charge removal corona output is applied to the charge removal/charging unit 236 (solid line portions z and z1 in the timing diagram).

After that, even if the trailing edge of the recording paper reaches a position 22 downstream from the transfer position @ point T, the recording paper is fed into the fixing unit 241 without instructing the servo control board 253 to reversely bias the transfer drive motor 2315. .

The fixing unit 241 thermally fixes the recording paper onto which the Y, M, C, and Bk toner images have been transferred, and discharges the recording paper onto a paper discharge tray 242 .

The main control board 251 energizes the static elimination unit 232 and the cleaning unit 233 at the timing when the trailing edge of the recording paper passes under the static elimination/charging unit 236.
#Electrify and clean the transfer belt 231 (
Timing diagram X).

When the repeat mode (copying multiple sheets) is specified, the main control board 251 controls the laser writing unit 215 at the same repeating cycle as described above in parallel with the transfer and fixing of the Bk toner image and the ejection of the paper. Instruct image writing using Y data and repeat the above (timing diagram f).

When the ejection of the final copy is completed and the cleaning and neutralization of the photoreceptor belt 211 and transfer belt 231 is completed, the operation is stopped and the operation returns to the initial state.

In addition, in monochrome copy mode, the above Y, M, C and Bk
Either one of the toner image formation and transfer process is performed, and in the two-color copy mode, the above Y is performed.

Any two of M, C, and Bk toner image formation and transfer steps are performed, and in the three-color copy mode, the above Y, M toner images are
, C, and Bk toner images and transfer steps are performed.

Next, control of the transfer belt 231 will be explained in more detail with reference to FIGS. 4c and 4d.

As described above, when the print start signal a changes to H level, the main control board 251 outputs an SO pulse to cause the servo control board 253 to control the transfer drive motor 23.
15, and starts image writing using Y data with the third pulse of the rotation detection signal d (3 rotations of the PC drive roller 2111), and then the fourth pulse plus PC encode. 81 pulses are output as the po-th pulse of signal e.

At this time, a counter for counting the number of pulses of the second transfer encode signal Q output by the second encoder 2317 (hereinafter referred to as a transfer counter) is cleared, and from then on, during normal rotation of the transfer drive motor 2315 (t 1 + t2 +
t3'), this counter is incremented by one count each time the second transfer encode signal Q rises. Note that the first encoder 2316 outputs pt2 pulses before detecting the rise of the first pulse of the second transfer encode signal Q.

After this, when 11 hours have elapsed, transcription starts, but as mentioned above, during this time the encoder 2116 outputs
The number of pulses Pp of the C encode signal e.

The number of pulses Ptl of the first transfer encode signal outputted by the first encoder 2316 is equal to each other.

The main control board 251 is configured such that the trailing edge of the recording paper is at the transfer position gl.
The R1 pulse is output at a timing at a distance Q2 from point T to instruct the servo control board 253 to reversely energize the transfer drive motor 2315. As a result, when the transfer belt 231 starts to reverse rotation (movement in the direction of arrow Vr force), (
t, 1 hour after R1 pulse), second encoder 2
At the falling edge of the second transfer encode signal Q outputted by 317, the transfer counter starts counting down. When the value of this counter becomes zero, the recording paper is transferred to the transfer drive motor 23.
Since this corresponds to the position where the first rise of the pulse of the second transfer encode signal Q is detected when normal rotation of the transfer drive motor 2315 is energized, the transfer drive motor 2315 is deenergized.

Here, the transfer drive motor 2315 is energized to rotate normally again, the rise of the second transfer encode signal a is detected, the transfer counter is incremented by 1, and after that, when the number of pulses in the first transfer encode signal reaches Pta, Transfer drive motor 2315 is deenergized. However, this pulse number Pta
Since the pulse frequency of the first transfer encode signal is 100 times the pulse frequency of the second transfer encode signal 2, the first encoder 2316 sets a number smaller than 100 to the second transfer encode signal after pulse S1. Signal Q
The number of pulses p output until the rise of the first pulse of
Set according to t2 (Keep Pt, 2+Pt, , constant).

In this way, backlash of the transfer belt 231 is eliminated and an unstable position of the second encoder 2317 is avoided.

After this, when 14 hours have passed, the leading edge of the M toner image reaches the position Ts of Q1 before the transfer position lT point, so S2
A pulse is output to instruct the servo control board 253 to energize the transfer drive motor 2315 in the normal direction, and the transfer counter starts counting up when the second transfer encode signal Q rises.

After outputting the S2 pulse, at time t1, the encoder 2116
Since the number of pulses of the PC encode signal e outputted by
The transfer belt 231 is aligned so that t1-Pt2-Pt, 3=constant) is equal to PP.

By controlling the transfer belt 231 as described above,
Eleven hours after the main control board 251 outputs the S 1 r s21 s3 and S4 pulses, the leading edge of the recording paper exactly coincides with the transfer position iT point.

By the way, in the apparatus of this embodiment, as described above, the amount of movement of the photoreceptor belt 211 is detected to set the forward conveyance of the recording paper and the start of toner image transfer, and the amount of movement of the transfer belt 231 is detected to perform recording. The paper is being aligned. Therefore, in order to perform overlapping transfer correctly, each must be driven at a designed speed. In this case, since the photoreceptor belt 211 is continuously rotating, it can be driven at a constant speed relatively easily. However, since the transfer belt 231 repeatedly stops, moves forward, and moves back, some variation in driving speed occurs. 5 Normally, this variation is absorbed in the time from when the leading edge of the recording paper matches the point P by backward conveyance until the start of transfer, but if there is a drive delay that exceeds this time due to some abnormality, e.g. If the backward conveyance speed does not rise to a specified speed due to changes over time or an overload of the transfer drive motor 2315, etc., transfer will start before the forward conveyance of the recording paper is completed.

Such an abnormality not only causes a shift in one color, but also causes damage to the photoreceptor belt 211, so the main control board 251 detects one rotation from the start of image writing using Y, M, C, or Bk data. When the signal d has four pulses and the PC encode signal e has a Po pulse, if the positioning of the recording paper by controlling the transfer belt 231 described above has not been completed, it is determined that an abnormality has occurred and an abnormality process is performed.

In abnormality handling, elements other than the transfer belt 231 are brought to an emergency stop, and the recording paper is ejected to the trailing end guide plate 239 side and its driving is stopped.

In addition, in abnormality processing, the recording paper is placed on the leading edge guide plate 238.
The transfer belt 2 may be discharged to the side, and the transfer belt 2 may be discharged to the side.
The guide plate 238 or 239 may be selected depending on the driving direction of the recording paper 31 or the position of the recording paper.

(Detailed description of the invention) As described in detail, the present invention is a recording device that forms an electrostatic latent image corresponding to the image on a flt carrier, develops it, and transfers it to a recording paper, which moves the recording paper back and forth. In an overlapping image recording apparatus of a type that performs overlapping recording by carrying a charge carrier on a moving means and reciprocating the recording paper by controlling the reciprocating means, a movement amount detection that detects the amount of movement of a circumferential surface of a charge carrier Have the means.

When the recording paper is transported back using the reciprocating means.

An abnormality occurs if the amount of movement a of the circumferential surface of the charge carrier after the formation of the electrostatic latent image of the next image to be transferred reaches a predetermined value before the recording paper reaches the predetermined forward transport start position. Set.

In other words, if the drive of the charge carrier and the conveyance of the recording paper are not consistent, an error will be set, so if the recording process is stopped based on this, the impact on the charge carrier etc. and the consumption of developer can be reduced. I can do it. Also, when setting an abnormality.

If you stop the recording process and eject the recording paper,
Improves operability. In this case, as shown in the example,
If a recording paper guide means is provided to receive the recording paper that has come off the reciprocating means, the recording paper may be ejected to the recording paper guide.

In addition to the laser printer type color copying apparatus shown as an embodiment of the present invention, for example, a type of color copying apparatus in which a photoconductor is directly exposed to light by optical scanning,
It is obvious that the present invention can be applied as is to color printers that receive RGBff1 from TV cameras and TV receivers and create color hard copies, or image editing devices that record single colors overlappingly to create superimposed images. .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing the mechanical structure of a color copying apparatus according to an embodiment. Fig. 2a is a block diagram showing the control system of the embodiment device, and Fig. 2b is a block diagram showing a part of it.6 Fig. 3 is a block diagram showing the configuration of the high voltage urging unit provided in the embodiment device. It is. FIGS. 4a to 4d are timing charts showing, by way of example, the main operations of the embodiment device. 1: Image scanner 11: Optical scanning system 111: Contact glass 112: Illumination lamp 1
13.114,115: Mirror 116: Condensing lens 12: Photoelectric conversion system 13: Image processing system 2:
Laser printer 21: Imaging system 211: Photosensitive belt (charge carrier) 2111.2112, 2113: Roller 2114: Rotating pulse generator 2115: PC drive motor 2116: Encoder 2114.2116: (Movement detection means) 212: Cleaning Unit 213: Static elimination unit 214: Charging unit 21
5: Laser writing unit (electrostatic latent image forming means) 216:
Developing unit (developing means) 216y, 216m, 216c, 216b: Developing device 2
161y, 2161m, 2161c, 2261b: Developing roller 22: Paper feeding system 221: Paper feeding cassette 222: Paper feeding roller 223 Ni registration roller 23: Transfer system 231: Transfer belt (reciprocating means) 2311.2312: Transfer roller 2313: Lift up roller 2315: Transfer drive motor 2316.2317: Encoder 232: Static elimination unit 233: Cleaning unit 234: Paper adsorption charging unit 235: Transfer unit (transfer means) 236: Static elimination/charging unit 237: Switching unit 23
8.239 Guide plate (recording paper guide means) 24: Fixing paper discharge system 241: Fixing unit 2411: Fixing roller 2412: Paper discharge roller 242: Paper discharge tray 25: Control system 251: Main control board (control means) 252. 253
: Servo control board 254: Operation & display board 255: High voltage control board 2
551.2552: High voltage biasing unit 256: Fixing heater control board

Claims (3)

[Claims] (1) A rotating charge carrier; an electrostatic latent image forming means that forms an electrostatic latent image corresponding to the original image on the charge carrier; a developer that develops the electrostatic latent image to form a visible image; means; transfer means for transferring the developed image onto recording paper; reciprocating means for carrying the recording paper and moving back and forth; and controlling the electrostatic latent image forming means to transfer the electrostatic latent image onto the charge carrier. forming an image, controlling the developing means to develop the electrostatic latent image, controlling the reciprocating means to transport the recording paper back and forth, and controlling the transfer means to develop the developed image. Transfer the image onto recording paper and perform image recording processing.
Thereafter, in the overlapping image recording apparatus, the apparatus includes: a control means that controls the reciprocating means to carry out the backward conveyance of the recording paper at least once and repeats the recording process; a movement amount detection means for detecting a movement amount, and the control means controls the reciprocating means to detect the next time before the recording paper reaches a predetermined forward transport start position when the recording paper is transported backwards by controlling the reciprocating means. An overlapping image recording apparatus characterized in that an abnormality is set when the amount of movement of the circumferential surface of the charge carrier after starting formation of an electrostatic latent image of an image to be transferred reaches a predetermined value. (2) The overlapping image recording apparatus according to claim 1, wherein the control means stops the recording process and ejects the recording paper when the abnormality is set. (3) Further, recording paper guide means is provided for receiving a portion of the recording paper that has deviated from the reciprocating means, and when the abnormality is set, the control means controls the reciprocating means to guide the recording paper toward the recording paper guide. Claim No. (2)
) Duplicate image recording device described in item 2.