JPS6076768A - Adjusting method of transfer with two-color copying method - Google Patents

Abstract

PURPOSE:To maintain good copying quality even if a copying mode is changed by changing either or both of the electrifying polarity and electrifying quantity of the preliminary electrification of an insulating belt according to each copying mode. CONSTITUTION:Copying paper is electrostatically attracted and conveyed by a preliminarily electrified insulating belt 24. The images of different colors are selectively transferred from two photosensitive bodies such as a photosensitive body 11 for red and a photosensitive body 12 for black, which are disposed in the upper stream and down stream positions in the conveying direction. The copied images of plural copying modes corresponding to the color selection are thus obtd. on the copying paper. The preliminary electrifying quantity of the belt 24 by a preliminary electrifying charger 28 is adjusted and the electrifying polarity and electrifying quantity of the belt 24 are changed according to each copying mode in order to improve the transfer efficiency of the transfer operation to be accomplished by transfer chargers 21 and 21'. The adequate transfer operation is thus made possible even if the copying mode is changed and the copying quality is satisfactorily maintained.

Description

[Detailed Description of the Invention] Technical Field The present invention transports copy paper using a pre-charged insulating belt, and supports selection from two photoreceptors disposed at upstream and downstream positions in the transport direction. The present invention relates to a transfer adjustment method in a two-color copying method that allows copying images to be obtained in several copying modes.

Prior Art In the above-described copying method, at least one photoreceptor is formed by a composite photoreceptor having at least two photoreceptor layers having different spectral sensitivities, and a light image of an original is irradiated onto the two photoreceptors without color separation. to create electrostatic latent images with different polarities or potentials on each photoreceptor, and each latent image is
A method is known in which a two-color copy image is obtained by developing an image using a different type of developer and then transferring it to copy paper. In this case, if the color of the transferred image obtained by copying using one photoconductor is color a, and the color of the transferred image obtained by copying using the other photoconductor is color b, which copying task should be selected? You can select from five copying modes depending on the type of printing: A, B 2 colors, A color removed, B color removed, all 8 colors, and all 1) color.

By the way, in the above-mentioned copying process, the insulating film belt is transported to the insulating light material, and the insulating film belt is usually pre-charged to attract and adhere the copy paper to the belt and also to charge the transfer charger during transfer. Operations are being carried out to reduce the voltage and avoid abnormal discharge.

However, in conventional copying operations, the amount of preliminary charge on the belt is only set to a constant value, so even if the condition is optimal for one copy mode, it is not sufficient for other copy modes. The mode is often inappropriate, and as a result, copying quality often deteriorates due to insufficient or excessive charging.

Purpose In view of the above points, the present invention provides two methods that can always maintain good copy quality even when the copy mode changes.
The purpose is to provide a color copying method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to drawings showing embodiments thereof.

In FIG. 1, the original placed on the original table 1 is placed on the lamp 2.
The light passes through the first mirror 3, second mirror 4, third mirror 5, and imaging lens 6, and reaches the nof mirror 7. The light beam passes through the -7 mirror 7 and the drum-shaped first photoreceptor 1.
1] and a drum-shaped second photoreceptor 12
It is split into a second beam of light directed toward .

The first light beam reflected by the half mirror 7 is reflected by the fourth mirror 8,
The first photoreceptor 11, for example, a red photoreceptor, is exposed to light through the fifth mirror 9.

The second light beam transmitted through the half mirror 7 is reflected by the sixth mirror 10 and is exposed to the second photoreceptor 12, for example, a black photoreceptor.

Although the following two colors, red and red, will be described, the present invention is not limited to these two colors.

A focus correction glass 13 and an aperture 1 are provided in the path of the first light beam for red.
4 is provided, and a filter 1 is provided in the path of the second light beam for black.
5. A diaphragm 16 is provided.

Around the first photoconductor 11, a primary charging device 17, a secondary charging device 18, an exposure position 19, a developing device 20, a first transfer charger 21, a cleaning device 22, and a potential erasing lamp 23 are installed in the rotation direction of the photoconductor. The electrostatic latent images are arranged in sequence and utilize the difference in spectral sensitivity of the photoconductive layer of the photoreceptor to form an electrostatic latent image of only a red image, which is visualized by the red developer of the developing device 20 and conveyed by the insulating film belt 24. Transfer it to the copy paper that will be used. After the transfer, the photoreceptor is cleaned and neutralized to complete one cycle.

Similarly, the primary charging device 17 (
In the case of black, the secondary charging device can be omitted),
The exposure position 19, the developing device 20 (contains developer of a different color, for example, black, from the developing device 20 disposed on the first photoreceptor 12), the second transfer charger 21', the cleaning device 22, and the potential erasing LED 23'. The first photoreceptor 1 is arranged
The black image is transferred onto copy paper conveyed by an insulating film belt 24 in the same manner as in the process.

The copy paper is sent out from the paper feed tray 26 by a paper feed roller 27, once stopped by a registration roller 35, and then fed again at a predetermined timing.

The insulating film belt 24, which is wound around the drive roller 36 and the driven roller 37 and corrected by the correction roller 38, is made of a dielectric material, and the belt position detector 39
Passage of the seam of the belt, that is, the home position is detected.

The belt 24 stops and waits immediately after the passage of the seam is detected by the belt position detector 39. Furthermore, this belt 24 starts in synchronization with the start of the registration roller pair 35,
A pre-charging charger 28 disposed opposite the correction roller 38 applies a predetermined charge to pre-charge the correction roller 38 to a predetermined potential.

However, this preliminary charge amount can be changed for reasons described later.

When the copy paper reaches the pre-charged insulating film belt 24, it is electrostatically attracted to the belt and is conveyed without relative slippage.

While being conveyed, the copy paper is neutralized by the pre-transfer static elimination lamp 43, and then the copy paper is charged by the first transfer charger 210.
The developed image (for example, a red image) on the photoreceptor 11 is transferred to the second photoreceptor 12 under the action of the second transfer charger 21'.
For example, a black image is transferred.

After the transfer, the photoreceptors 11 and 12 are cleaned, neutralized if necessary, and the process from the primary charging is repeated again. On the other hand, after the transfer, the copy paper is separated from the belt 24 by the action of the separation charger 29 and the separation claw 30, is fixed while passing between the fixing roller 31 and the pressure roller 32, and is sent to the paper output tray 33, at which time it is discharged. It contacts the brush 44 and discharges the electrical charge.

After the copy paper is separated, the insulating film belt 24 is cleaned by a cleaning blade 40 to remove any developer that has adhered thereto, and a static elimination charger 42 is applied to the counter electrode plate 41.
The static electricity is removed by discharge, and the belt position detector 39 stops at the standby position as detected by the belt position detector 39.

Copying work using the first photoreceptor 11 as described above (hereinafter referred to as
If the copying operation is performed using both the first copying operation and the copying operation using the second photoreceptor 12 (hereinafter referred to as the second copying operation), two colors of red and black will be printed on the copy paper. A duplicate image is obtained depending on the mode. On the other hand, if only the first copying operation is performed, copies in black or all red mode can be obtained;
On the other hand, if only the second copying operation is performed, copies in red-out or all-black mode can be obtained.

As mentioned above, in the first copying operation and the second copying operation, the transfer operation is performed by the transfer chargers 21 and 21', respectively, and the transfer efficiency at that time generally depends on the transfer efficiency from the transfer chargers to the insulating film belt 2.
It is determined by the charge given to 4. When an electric charge is applied to the insulating film belt l-2<, the potential of the belt 24 increases by that amount. Therefore, the efficiency of the transfer by the transfer charger can be estimated from the potential fluctuation of the belt after the transfer operation is performed by the transfer charger.

Figure 2 shows the transfer efficiency with respect to the potential fluctuation of the belt after discharging the transfer charger.
~1500V, below which the efficiency gradually decreases, and above that the efficiency rapidly decreases. The reason why the efficiency is low when the potential fluctuation is small is considered to be due to insufficient charging of the belt, and the reason why the efficiency is low when the potential fluctuation is wide is considered to be due to excessive charging.

From this result, in order to obtain good transfer efficiency in the copying machine shown in FIG.
It is desirable to set it to 300-1500V.

The potential fluctuation of the insulating film belt 24 can be adjusted by adjusting the discharge amount of the transfer charger 21 or 21', and therefore the applied voltage. However, since a high voltage is applied to the transfer charger, it is difficult to finely adjust it, and even if it were done, it would be expensive. In addition to adjusting the voltage applied to the transfer charger, the belt potential fluctuation can be adjusted by adjusting the belt potential before transfer. In this embodiment, in order to manufacture the device simply and at low cost, the potential of the belt before transfer is adjusted, that is, the preliminary charging charger 2
A method is adopted in which potential fluctuations of the belt 24 are adjusted by adjusting the amount of preliminary electrification of the belt 24 as shown in FIG.

Generally, if the voltage applied to the transfer charger is kept constant and the potential of the belt conveyed to the transfer charger is varied, the potential of the belt after passing the transfer charger changes as shown in FIG. The horizontal axis is the belt potential before the charger, and the vertical axis is the belt potential after the charger. Also, the two straight lines show the results when two different voltages Va and Vb are applied to the transfer charger (however, Vb
>Va).

In the figure, it can be seen that the relationship between the belt potential before the charger and the belt potential after the charger is a linear relationship.

Also, the slope of the straight line is smaller than ] (i.e. 45°
(below). The fact that the slope of the straight line is less than 1 means that when the voltage applied to the transfer charger is constant, the greater the belt potential before the charger, that is, the amount of preliminary charge on the belt, the greater the potential of the belt before and after the charger. This means that the potential difference, that is, the belt potential fluctuation due to discharge of the charger becomes smaller.

By adjusting the amount of preliminary electrification of the belt in this way, it is possible to adjust fluctuations in the belt potential even if the voltage applied to the transfer charger is constant.

Hereinafter, in the copying machine shown in FIG.
By adjusting the amount of charge on the belt, it is possible to adjust the fluctuation of the belt potential before and after the transfer charger 21 or 21' (i.e., adjust the charge applied to the belt), thereby controlling the first and second copying operations. A specific example for performing efficient transfer work will be explained below.

What needs to be noted here is that when the first copying operation or the second copying operation is performed independently, that is, in the all-red or black-out mode or the all-black or red-out mode, the transfer charger Since only either the charger 21 or the second transfer charger 21' is operated, it is only necessary to consider the amount of preliminary charging by the preliminary charging charger 28, but in the case of two-color mode, Both transfer chargers 21, 21'
, the belt potential in front of the second transfer charger 21' must take into account not only the amount of charge by the preliminary charger 28 but also the amount of charge by the first transfer charger 21.

First, the transfer conditions in the two-color mode will be explained based on FIG. 4. In this case, as shown in the figure, the backup charger 2
8, the insulating film belt 24 has V□=approximately -50
Charge to 0V. As described above, this charging causes the copy paper to be electrostatically attracted to the belt 24. In order to charge the belt 24 to -500 volts, a voltage of about 4.5 KV is applied to the preliminary charger 28. The belt 24 pre-charged in this way is conveyed to the first transfer charger 21 together with the copy paper held by suction, and the potential fluctuation is reduced by 13.
The discharge action is applied to the extent that the belt potential after charging becomes approximately 00V, that is, approximately v=soov.

At this time, a red image is transferred from the first photoreceptor IJ to the copy paper. ■In order to get the voltage to about 22,800v, the first step is to
A voltage of about 5.5 KV is applied to the transfer charger 21. As before, this voltage is held constant.

The copy paper and belt that have undergone the first copying are then conveyed to the second transfer charger 21'. The second transfer charger 21' is moved by the first transfer charger 21 so that v =
Based on the belt potential raised to soov, discharge is performed to further raise the belt potential to about 1300V. The applied voltage at this time is approximately 6.5 KV. This applied voltage is also constant. During this discharge, a black image is transferred from the second photoreceptor 12 to the copy paper.

The two-color mode copying operation is performed as described above.

As explained in relation to FIG. 2, in order to improve the transfer efficiency, it is desirable that the belt potential fluctuation is 1300 to 1500V, and as in the transfer conditions for the 02 color mode mentioned above, the potential fluctuation should be reduced to 1300V. It is not necessarily desirable from the standpoint of transfer efficiency to limit the transfer rate to 100%. The reason for sacrificing transfer efficiency in this way will be described later.

Next, the transfer conditions for the all-red or blackout mode in which only the first copying operation is performed will be explained. In this case, the insulating film belt 24 is precharged to V=-700V as shown in FIG. The voltage applied to the preliminary charger 28 at this time is approximately 5.0 I (V).

As explained with reference to FIG. 3, if the belt potential before the charger is low, the amount of charge applied will increase even if the voltage applied to the transfer charger is constant, and as a result, the belt potential fluctuation will increase. Therefore, the preliminary charge amount is -500
According to this transfer condition where the voltage was reduced from V to -700V,
The variation in belt potential due to the discharge of the first transfer charger 21 becomes a larger value, for example 1400V, than in the case of the two-color mode described above (1300V). In this way, the potential fluctuations are large (although the preliminary charging potential is originally low (-700V), so the belt potential after the first transfer charger 21 itself is 800V in the two-color mode). ), for example, 700 V. In this way, the belt potential fluctuation caused by the first transfer charger 21 is set to be wider than that in the two-color mode, which improves transfer efficiency and produces high-quality copy products. In this example, considering the results shown in Figure 2, the transfer conditions are set so that the best transfer efficiency can be obtained when the potential fluctuation is 1400 V, but when the potential fluctuation is 1400 V or more, For devices that are capable of obtaining higher transfer efficiency, it is desirable to set the potential fluctuation value accordingly.

Next, the transfer conditions for the all-black or red-out mode in which only the second copying operation is performed will be described. Figure 6 shows the conditions, and as shown in the figure, the preliminary charging potential in this case is 700V.
The applied voltage at this time is approximately -50 Kv. The pre-charged bell i 24 passes through the first transfer charger 21 and is conveyed to the second transfer charger 21' while adsorbing and holding the copy paper. Since the first copying operation is not performed, no charge is applied from the first transfer charger 21.
Therefore, the preliminary charging potential (1) is maintained as the potential (2) after the first transfer charge. The potential of the belt 24 charged to ■2 near 00■ rises by about 400 V due to the discharge of the second transfer charger 21', and becomes v322100V.
becomes. The fact that efficient transfer is performed during this potential rise is the same as in the case of the above transfer conditions (FIG. 5) in which only the first copying operation is performed. Similarly, the potential fluctuation value may be set to 1.400 V or more depending on the case.

The broken line in Figure 6 shows the state when the transfer condition is 2-color mode even though it is in full black or red outline mode, that is, when the preliminary charging potential is set to Vl (V2) = -500V. ing. In this case, the belt potential before entering the second transfer charger 21' is low (.), so the belt potential fluctuation after discharge is extremely large, for example, about 2500 V. In this case, the belt 24 and its belt An excessive charge is applied to the upper copy paper, resulting in poor transfer.

On the other hand, V3- V2 (Vl) = 1.4.00 V
Under the present transfer conditions, which are kept at a minimum, there is no concern about such transfer defects.

As can be seen from the above description, in this embodiment, in the all-red or black-out mode, and in the all-black or red-out mode,
Insulating film bell! - 240 pre(iifi) By adjusting the charge amount, optimum transfer conditions are created for each of the first transfer charger 21 and the second transfer charger 21', thereby obtaining the best transfer efficiency.

As mentioned above, under the two-color mode transfer conditions (Figure 4),
The belt potential fluctuation during transfer is suppressed to 1300V, sacrificing transfer efficiency to some extent, but this is adjusted so that both the transfer efficiency in the first copying operation and the transfer efficiency in the second copying operation are as high as possible. This is to do so. If the amount of preliminary charging is lowered as shown in FIG. 5 in order to improve the transfer efficiency in the first copying operation, in that case, the belt potential after the first transfer charger 21, that is, the potential of the second transfer charger 21' will be lowered. Since the previous belt potential also drops, the second transfer charger 21' cannot perform proper charging work. However, if the specifications of the photoreceptor 11 or 12 are changed, the transfer conditions shown in FIG. Good.

Effects As described above, according to the present invention, the charging polarity and amount of pre-charging of the insulating film belt are changed according to each copying mode, thereby always maintaining appropriate transfer conditions even when the copying mode is changed. Since the transfer work is carried out in the same way, good copy quality can be maintained regardless of the copy mode.

[Brief explanation of drawings]

Fig. 1 is an overall side sectional view of a two-color copying machine using the method of the present invention, Fig. 2 is a graph showing the relationship between transfer efficiency and fluctuations in belt potential due to discharge of the transfer charger, and Fig. 3 is a graph showing the relationship between transfer efficiency and the transfer charger voltage. FIG. 4 is a graph showing the relationship between the belt potential before discharge and the belt potential after discharge when voltage is used as a parameter. FIG. 4 is a graph showing an example of charging conditions in two-color copying mode according to the method of the present invention. FIG. FIG. 6 is a graph showing an example of charging conditions in one-color copying mode, and FIG. 6 is a graph showing an example of charging conditions in another one-color copying mode. 24... Insulating base/l/ G Kazuo Wakasugi, Commissioner of the Japan Patent Office on the 24th 1 Display of the case 1984 Patent Application No. 184557 2 Name of the invention Transfer control method in a two-color copying method 3 Relationship with the case by the person making the amendment Patent Information on the applicant Statement Name (Name) (674) Ricoh Co., Ltd. 4 Agent 6 Column for detailed explanation of the invention of the specification subject to amendment and drawings. 7 Contents of amendment J) Change the description “copy paper” on page 6, line 18 of the specification to
Photoreceptor], 1. , amended to 12 J, 2) same page 6, 1
The statement "next" in line 9 was corrected to "then the copy paper." 3) The statement in lines 13 to 20 of page 13 [as above...] ...The reason will be explained later. 4) On page 14, lines 4, 10, and 16, the statement “-7
Corrected oo'VJ to r-800VJ, 5) Same No. 14 Tei 1
The description on the 4th line r1.400VJ is corrected to 1500VJ. 6) The description on page 15, lines 2 to 8: ``In this example,
It is desirable that... 7) Delete the statement "In some cases, the same is true." on page 16, lines 5 and 6, 8) Delete the statement r on page 16, line 13. ' 2500 V J [22
Corrected to 00VJ, 9) Replaced Figure 5 of the drawing with Figure 5 of the attached drawing, 10)
Figure 6 of the drawings has been replaced with Figure 6 of the attached drawings. Fig. 5 3 v g p= 821 (5,5”) (5,56) Zino 2 [ (-5, OKV) (6,5KV)

Claims (1)

[Claims] Copy paper is conveyed by a pre-charged insulating belt,
Images of different colors are selectively transferred from two photoreceptors placed at upstream and downstream positions in the transport direction, and copied images in several copying modes corresponding to the color selection described above are obtained on copy paper. A transfer adjustment method in a two-color copying method, characterized in that either or both of the charge polarity and the amount of charge of preliminary charging of an insulating belt are changed according to each copy mode.