JPH05249778A - Image forming device - Google Patents

Abstract

PURPOSE:To excellently form an image by performing proper preprocessing (adding a curl amount, a heating amount and an electrostatic charging amount) to a transfer material in accordance with the water content of the transfer material. CONSTITUTION:A resist roller R is rotated in synchronism with a photosensitive drum and feeds the transfer material P to a downstream side. At such a time, a heating roller R2 is heated according to the water content contained by the transfer material P. Therefore, the lower surface of the transfer material P' which passes the resist roller R is condensed and the specified curl amount is added to the transfer material. The transfer material P' thus curled is hardly brought into contact with the photosensitive drum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for transferring a visible image onto a transfer material by using an electrophotographic method, and more specifically, to a water content of the transfer material before the transfer of the visible image. The pretreatment applied to the transfer material according to the amount of

[0002]

2. Description of the Related Art Conventionally, various image forming apparatuses have been proposed. FIG. 14 shows an example of a copying machine adopting a general electrophotographic system.

The copying apparatus C has an image forming section D therein, and the image forming section D has a photosensitive drum (image carrier) 1. The photosensitive drum 1 is rotatably supported by the main body of the apparatus C, and is configured to rotate in a direction indicated by an arrow by a driving unit (not shown). Around the photosensitive drum 1, in order, a primary charging device 2 that uniformly charges the surface of the photosensitive drum 1, and a toner is attached to an electrostatic latent image (described later) formed on the photosensitive drum 1. A developing device 3 for forming a toner image, a transfer charging device (transfer charging means) for transferring the toner image onto a transferred transfer material P (described later).
5, a separation charging device (separation charging means) 6 for preventing the transfer material P from adhering to the photosensitive drum 1, a cleaning device 7 for removing the toner remaining on the photosensitive drum 1 after the transfer, the photosensitive drum 1 A static eliminator 9 is provided for eliminating static electricity on the surface of the. The photosensitive drum 1 is a seamless one using a photoconductor and a conductor.

On the other hand, a part of the upper surface of the main body of the copying apparatus C is formed of a document glass G on which the document B is placed, and the document B is placed between the document glass G and the image forming section D. Exposure unit L that irradiates the photosensitive drum 1 with light corresponding to the image
Are arranged. The exposure unit L has an illumination lamp 10 for illuminating the original document B, and the vicinity of the illumination lamp 10 is illuminated by the illumination lamp 10 for the original document B.
Mirrors 11a, 11 to change the optical path of the light reflected by
b and 11c are provided. Further, the illumination lamp 10 and the mirrors 11a, ... 11c are configured to be integrally moved along the original glass G by a driving unit (not shown) so that the entire original B is illuminated. Further, a lens 12 and a mirror 13 are arranged on the optical path of the light reflected by the mirrors 11a, ..., 11c, and the mirror 13 is provided after the light passes through the lens 12.
It is configured to be reflected on the photosensitive drum 1 and to be irradiated onto the photosensitive drum 1.

Further, two cassettes K1 and K2 are detachably supported on the right side surface of the copying machine C, and a transfer material P is stored inside each of these cassettes K1 and K2. Feeding rollers 15 and 16 are respectively arranged above the cassettes K1 and K2 on the downstream side (on the left side in the drawing) so as to contact the transfer material P, and these feeding rollers 15 and 16 are not provided. It is configured to be rotationally driven by the illustrated driving means. The transfer material P fed by these feeding rollers 15 and 16 slides on the guide plates J1 and J2, and is further fed to the photosensitive drum 1 by the registration roller R. There is.

Further, on the downstream side of the separation charging device 6,
A transfer device 19 for transferring the transferred transfer material P to the further downstream side is provided, and the transfer device 19 includes a roller 20 which is rotationally driven by a drive unit (not shown), and a device C.
Roller 21 rotatably supported on the main body of the belt, and belt 22 wound between these rollers 20 and 21.
And have. Further, a fixing device 23 is arranged on the downstream side of the conveying device 19 and is configured to fix the toner image on the transferred transfer material P.

Next, the general operation of the copying apparatus will be described.

Now, when the operator places the document B on the document glass G and presses a switch (not shown), the photosensitive drum 1 starts to rotate in the direction of the arrow. Then, predetermined rotation control and potential control processing (preprocessing) is performed on the photosensitive drum 1, and when these controls are completed, the illumination lamp 10 scans the document B. At this time, the illumination lamp 10 is turned on to irradiate the entire document B with light. The irradiated light is reflected by the original B, further reflected by the mirror 11a, etc., and is irradiated onto the photosensitive drum 1 along the optical path indicated by the alternate long and short dash line in the figure. An image corresponding to the original image is drawn on the photosensitive drum 1 as the photosensitive drum 1 rotates.

Since the surface of the photosensitive drum 1 is charged to a uniform potential by the primary charging device 2,
An electrostatic latent image corresponding to the original image is formed on the surface based on the exposure by the exposure unit L. Such an electrostatic latent image is
Since the photosensitive drum 1 faces the developing device 3 as the photosensitive drum 1 rotates, toner is attached to the electrostatic latent image and is visualized as a toner image.

On the other hand, in parallel with such toner image formation, the feeding rollers 15 and 16 of the cassettes K1 and K2 in which the transfer material P of a designated size is stored are rotationally driven, and the transfer material P is transferred. It is sent out from the cassettes K1 and K2. Next, the registration roller R feeds the fed transfer material P between the photosensitive drum 1 and the transfer charging device 5 in synchronization with the rotation of the photosensitive drum 1. When the transfer material P is fed, the transfer charging device 5 is activated and the transfer material P
A high voltage is applied between the photosensitive drum 1 and the transfer charging device 5 via the. As a result, the toner image formed on the photosensitive drum 1 is transferred onto the transfer material P. Next, the separation charging device 6 charges the transfer material P after the transfer, and neutralizes the electric charge applied to the transfer material P by the transfer charging device 5. Therefore, the transfer material P thus neutralized is placed on the belt 22 of the transport device 19 without adhering to the photosensitive drum 1. Then, the placed transfer material P is conveyed to the fixing device 23, fixed by the fixing device 23, and then discharged from the main body of the copying apparatus C.

The surface of the photosensitive drum 1 after the transfer is cleaned by the cleaning device 7 to remove the residual toner as the photosensitive drum 1 rotates, and the static eliminator 9 is removed. Is discharged by.

[0012]

By the way, in the above-mentioned image forming apparatus (copying apparatus), the larger the water content of the transfer material P, the later the peeling timing of the transfer material P from the photosensitive drum 1 is delayed. was there. Further, when the water content was low, the transfer was performed well, but when the water content was high in a high humidity environment, image omission called transfer omission was likely to occur. This is because when the water content is large, the surface resistance of the transfer material P is reduced, and the charge applied to the transfer material P by the transfer / separation charging device escapes, resulting in poor charging.

Therefore, according to the present invention, an image forming is performed in which the transfer material is appropriately pretreated (giving a curl amount, a heating amount, a charging amount, etc.) in accordance with the water content of the transfer material, thereby performing an excellent image formation. The purpose is to provide a device.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an image carrier on which a toner image is formed, and a transfer for transferring the toner image on the image carrier to a transfer material. In an image forming apparatus including a charging unit and a separation charging unit that removes the charge of the transfer material on which the toner image is transferred, the amount of water contained in the transfer material is directly or indirectly detected. Detecting means, a transfer material pre-processing means for performing a certain processing on the transfer material before transferring the toner image so that at least one of separation and transfer of the transfer material is performed properly, Control means for controlling the transfer material pretreatment means based on a signal from the detection means.

In this case, the detecting means may include a humidity detecting device for detecting the humidity of the atmosphere around the transfer material.

Further, the detection means includes a temperature detection device for detecting the temperature of the atmosphere around the transfer material, and the control means is based on the detection results from the humidity detection device and the temperature detection device. Then, the amount of water contained in the transfer material may be calculated.

Further, the transfer material pretreatment means may be a curl imparting means for curling the transfer material.

In this case, the curl imparting means has a pair of rollers, one of the rollers has a roller heating means, and the control means controls the temperature of the roller heating means. Good.

Further, the transfer material pretreatment means may be a transfer material heating means for heating the transfer material from both sides.

In this case, the transfer material heating means has a pair of rollers, each of these rollers has a roller heating means, and the control means controls the roller heating means. May be.

Further, the transfer material pretreatment means may be a preliminary charging means for charging the transfer material.

Further, the detection means includes a basis weight detection device for detecting an amount corresponding to the thickness of one transfer material, and the control means includes the humidity detection device, the temperature detection device, and The amount of water contained in the transfer material may be calculated based on the detection result from the basis weight detection device.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view showing the structure of a copying apparatus C as an image forming apparatus according to the present invention. Note that FIG.
The same parts as those of the prior art shown in FIG.

In the copying machine C, an environment sensor (detection means) 30 is attached above the downstream side of the cassette K1 (on the left side in FIG. 1). The environment sensor 30 is a temperature sensor as will be described later with reference to FIG. It has a (temperature detection device) 30a and a humidity sensor (humidity detection device) 30b. The temperature sensor 30a and the humidity sensor 30b are configured to detect the humidity and temperature near the transfer material P stored in the cassettes K1 and K2.

Further, a registration roller (curl imparting means) R is disposed downstream of the feeding rollers 15 and 16, and the registration roller R feeds the transfer material P to the transfer material P. It is configured to give the proper curl.

Next, the registration roller R will be described with reference to FIG.

The registration roller R is a pair of rollers R.
1 and R2, and these rollers R1 and R2 are rotatably supported by the main body of the apparatus C, respectively.

Of these, the roller R1 is a core metal 1 made of aluminum.
01, and the core metal 101 has a cylindrical shape with a thickness of 3 mm. The core metal 101 is rotatably supported by the main body of the apparatus C, and a silicon rubber layer 102 is attached to the outer periphery of the core metal 101. The silicone rubber layer 102 has a thick cylindrical shape with a thickness of 7 mm, and the outer peripheral surface of the silicone rubber layer 102 has a PTFA layer (thickness 20 μm).
m) covered by 103. A heating roller R2 is arranged below the roller R1 having such a structure, and the heating roller R2 is made of iron or aluminum.
Have five. The core bar 105 has a thick-walled cylindrical shape with a thickness of 5 mm, and the core bar 105 is rotatably supported by the main body of the apparatus C. A halogen heater (roller heating means) 106 is provided inside the core bar 105 and is configured to heat the surface of the heating roller R2. This halogen heater 106 is a heating roller R2.
The core metal 105 has the same length as the above, and the outer peripheral surface of the core metal 105 is covered with a PFA layer 107 (thickness 50 μm). Further, a thermistor 109 is in contact with the surface of the heating roller R2, and is configured to detect the surface temperature of the heating roller R2.

The hardness of the heating roller R2 is 60 °.
As described above (Asker A hardness) and the hardness of the roller R1 is 30 °, the outer shape of the roller R1 is a shape in which the portion in contact with the heating roller R2 is dented as shown in detail in FIG. Has become. Further, the contact pressure of both rollers is 2.
They are abutted against each other at 5 kg, and their outer diameters are both 30 m.
m.

Next, the temperature setting circuit M of the halogen heater 106 will be described with reference to FIG.

The temperature setting circuit M has a CPU 110, and the temperature sensor 30a and the humidity sensor 30b are connected to the CPU 110. In addition, the CPU 11
0 is connected to the ROM 111.
As will be described later, the mixing ratio-curl amount-heating roller R
Data regarding the relationship between the two surface temperatures and the temperature correction amount (described later) is stored. Further, a RAM 112 is connected to the CPU 110, and the RAM 112 is a memory area for executing calculation processing. Furthermore, the CPU 110 includes a halogen heater power source 113.
The halogen heater 106 is connected to the halogen heater 106 via the above, and is configured to send a signal according to the calculation result to the halogen heater power source 113 to heat the halogen heater 106 to a predetermined temperature.

On the other hand, the thermistor 109 is connected to the halogen heater power source 113 via a temperature control circuit 115, and is configured to perform feedback control so that the temperature of the halogen heater 106 becomes a predetermined temperature. There is.

Next, the data stored in the ROM 111 will be described with reference to FIG.

The first quadrant in FIG. 4 is the registration roller R.
Amount of curl of the transfer material after passing through the heating roller R2
It shows the relationship with the surface temperature of.

The transfer material P is so-called PPC.
Paper (basis weight 64g / m ² , A4 size) is used,
The curl amount is measured by the so-called hanging method. Further, the feeding direction of the transfer material P is the lateral direction, that is,
The direction is such that the long side of the transfer material P is parallel to the rotation axis of the heating roller R2. Further, in order to know the change of the curl amount according to the environment, the transfer material P was left in three kinds of environments with a mixing ratio (water weight in 1 kg of air) of 3,13,23 g / kg. The amount of curl was examined for the one that was sufficiently familiar with the environment. 120a, 120 in the figure
b and 120c are the mixing ratios 3, 13 and
The curl amount of the transfer material P left in an environment of 23 g / kg is shown.

From the figure, it can be seen that the higher the surface temperature of the heating roller R2, the larger the curl amount. Further, it can be seen that the greater the water content of the transfer material P, the greater the curl amount. It is considered that this is because the higher the water content, the larger the rate of evaporation of water when heated and the larger the amount of shrinkage.

The second quadrant in FIG. 4 shows how much curl amount is required for the transfer material P placed in an environment of a certain mixing ratio to perform good separation. However,
The transfer material P of interest here is the same PPC paper as in the first quadrant, and its feeding method is the same lateral feeding as in the first quadrant.

A region 120d in the drawing is a region where a conveyance error such as a paper jam occurs because the curl amount is too large, and a region 120e is a region where a separation defect occurs because the curl amount is too small. Therefore, the area 120f sandwiched between the area 120d and the area 120e is an area where neither conveyance failure nor separation failure occurs, and in particular, the solid line 120g shown in the area 120f is the optimum value of the curl amount. is there.

From the figure, it is understood that the larger the mixing ratio (g / air 1 kg), the larger the curl amount is required.
Such a large curl amount is required for the transfer material P.
This is because the water content of is large, which is disadvantageous for separation.

Based on the data of FIG. 4 described above, the surface temperature of the heating roller R2 is set to obtain the optimum curl amount only by obtaining the air mixing ratio in the vicinity of the transfer material. You can decide what to do.

For example, the optimum curl amount of the transfer material P left under the environment of the mixing ratio of 13 g / kg is 24 mm according to the dotted line 120h ₁ , and in order to obtain this curl amount, the dotted line 120h ₂ and the curve 120b ( It can be seen that the surface temperature of the heating roller R2 should be set to 120 ° C. from the intersection of the curve of the surface temperature of the heating roller and the curl amount for the transfer material P left in the environment of the mixing ratio of 13 g / kg. .. However, it is not actually necessary to heat to 120 ° C. Because the transfer material P is heated by the heating roller R2, the water content of the transfer material P immediately before the separation step is lower than that before the sheet feeding, which is advantageous for the separation, and the above-mentioned 2
This is because a curl amount of 4 mm is not necessary. Therefore, it was not necessary to raise the surface temperature to 120 ° C., and the temperature correction amount was −20 ° C. according to the experiment. That is, under the environment of the mixing ratio of 13 g / kg, the surface temperature of the heating roller should be set to 100 ° C. (the curl amount corresponds to 19 mm). Strictly speaking, the temperature-corrected amount varies depending on the mixing ratio, but the separation was good in practice even when fixed at -20 ° C. Also, the mixing ratio is 3 g / kg,
In the case of an intermediate value other than 13 g / kg and 23 g / kg, the desired surface temperature is obtained by interpolating the curves 120a, 120b and 120c.

Such data is stored in the ROM 111 and is used by the CPU 110 for calculation as described above.

Next, the operation of the above embodiment will be described with reference to FIG.

When the operator presses a switch (not shown), the temperature sensor 30a and the humidity sensor 30b are activated, and the detected data are transmitted to the CPU 110 (S).
1). Then, the CPU 110 calculates the mixing ratio based on the transmitted data (S2). Next, the CPU 110
The optimum value of the surface temperature of the heating roller R2 is calculated based on the calculated mixing ratio and the data stored in the ROM 111 (S3). At this time, the correction of the surface temperature obtained by the calculation is performed as described above. Further, the CPU 110 sends a signal to the halogen heater power supply 113 to control the output voltage of the halogen heater power supply 113 (S4), and heats the halogen heater 106 (S).
5). On the other hand, the surface temperature of the heating roller R2 is the thermistor 1
The monitoring data is monitored at 09 (S6), and the measurement data by the thermistor 109 is sent to the temperature control circuit 115. The temperature control circuit 115 determines whether or not the surface temperature is equal to the target temperature based on the surface temperature data (S7). If the surface temperature and the target temperature are equal, the halogen heater power supply 1
The output of 13 is maintained as it is (S8), and if the surface temperature and the target temperature are different, the output of the halogen heater power supply 113 is corrected (S9).

Then, the heating roller R2 and the roller R1
The lower surface of the transfer material P passing between the heating roller R and
Since it is heated by 2, the water on its lower surface evaporates and dries, resulting in contraction. On the other hand, since the upper surface of the transfer material P is not directly heated, water remains and does not shrink. Therefore, the transfer material P'passed between the rollers R1 and R2 is formed with an appropriate downward curl amount as shown in FIG.

As a result, even if the transfer material P passes through the registration roller R and comes into contact with the photosensitive drum 1, an appropriate curl amount is provided, and therefore the transfer material P is easily separated by the separation charging device 6 after transfer, Therefore, separation failure can be avoided.

Further, the curl amount is not so large that a so-called conveyance failure does not occur.

Next, another embodiment of the present invention will be described with reference to FIGS. The same parts as those shown in FIGS. 1 to 5 are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 6 shows the structure of a transfer material moisture removing device (transfer material heating means) Q. The moisture removing device Q is arranged at the same position as the registration roller R of the above-mentioned embodiment, and is a cassette. The transfer material P from K1 and K2 is conveyed to the transfer charging device 5. Further, the water removing device Q includes a pair of the heating rollers R2 described above,
Each heating roller R2 has a halogen heater 106. The halogen heater 106 is connected to the above-mentioned temperature setting circuit M (FIGS. 3 and 5), and is configured to control the temperature of each heating roller R2. Further, the feedback control (FIGS. 3 and 5) is also performed based on the measurement result of the thermistor 109 attached to the surface of each heating roller R2.

Next, the data used for the temperature control of the heating roller R2 will be described with reference to FIG. The data is stored in the ROM 111 shown in FIG.

FIG. 7 shows the relationship between the surface temperature of the heating roller R2 and the basis weight required to sufficiently remove the water content of the transfer material. The basis weight (g / m ² ) is an amount corresponding to the thickness of one transfer material, and is measured by the basis weight detection sensor T described later.

Three curves 220a, 220b, 2 in the figure
20c shows the measurement results under the environment in which the mixing ratios were 3, 13, and 23 g / kg, respectively. From this, it is understood that the surface temperature of the heating roller R2 needs to be increased as the basis weight of the transfer material P increases and the mixing ratio increases.

On the other hand, the basis weight detection sensor T is provided on the guide plate J1 (FIG. 1) arranged on the downstream side of the cassettes K1 and K2.
The grammage detection sensor T detects the grammage (g / m ² ) of the transfer material P sliding on the guide plate J1, that is, the amount corresponding to the thickness of one transfer material. Is configured to. The configuration of the grammage detection sensor T and the operating method thereof will be described below with reference to FIG.

The lower surface of the guide plate J1 is shown in FIG.
As will be described in detail below, a pair of L-shaped members 200a and 200b
Are attached so as to face each other, and a detection lever 202 is rotatably supported on these L-shaped members 200a and 200b via a rotation shaft 201. The detection lever 202 is substantially L-shaped, and its upper end is configured to be projectable from an opening Ja formed in the guide plate J1. Further, a support member 203 is attached to the lower surface of the guide plate J1, and a tension spring 2 is provided between the support member 203 and the lower end of the detection lever 202.
05 is attached. A protrusion 202a is formed on the detection lever 202 on the side opposite to the support member 203, and the pressure sensor 2 is provided at a position facing the protrusion 202a.
06 is provided. Then, when the detection lever 202 rotates in the direction shown by the arrow F in FIG. 8A, the protrusion 202a contacts the pressure sensor 206. The pressure sensor 206 is connected to the CPU 110 of the temperature setting circuit M, and the arrow H in FIG. 8A indicates the direction in which the transfer material P is conveyed.

In FIG. 8B, the transfer material P is the guide plate J.
1 shows the rotation position of the detection lever 202 when the transfer material P is not passing over the guide plate 1, and FIG.
The detection lever 202 rotates while passing over 1.
The lower end of the detection lever 202 is in contact with the pressure sensor 206.

The basis weight detection sensor T having the above structure
Are mounted not only on the guide plate J1 but also on the guide plate J2.

Next, the operation of the above embodiment will be described.

Now, when the transfer material P is not fed, the detection lever 202 uses the tension spring 205 and the support member 203 to detect the pressure sensor 2 as shown in FIG. 8B.
It is held at a position where it does not contact 06. Next, the transfer material P is sent out by the feeding roller 15 or the like to be guided by the guide plate J.
1 and J2, the transfer material P pushes the upper end of the detection lever 202 in the direction of arrow H as shown in FIG. 8 (c), and the detection lever 202 moves about the rotary shaft 201. Rotate in the direction of arrow F. The projection 202a at the lower end of the detection lever 202 contacts the pressure sensor 206 and presses the pressure sensor 206 with a constant pressure. Here, the transfer material having a larger basis weight has higher rigidity and the deflection of the transfer material P shown in FIG.
The pressure applied to is increased.

Next, the CPU 110 receiving the signal from the pressure sensor 206 calculates the basis weight of the transfer material P based on the data shown in FIG. Then, based on the data (FIG. 7) stored in the ROM 111, the heating roller R
The surface temperature (target value) of 2 is obtained.

Further, the transfer material P is the guide plate J.
Since the two heating rollers R2 are both heated when being sent on the first and J2 and passing through the moisture removing device Q,
Both the upper and lower surfaces of the transfer material P are heated. Therefore, the water does not evaporate from each surface of the transfer material P, the water does not remain on the upper surface or the lower surface, and the water content of the transfer material P can be reduced. Further, no curl is formed on the transfer material P after passing through the water removing device Q.

As a result, the water removing device Q removes the water of the transfer material P, so that transfer and separation can be properly performed.

Further, since the surface temperature of the heating roller R2 is adjusted according to the change in the water content of the transfer material P detected by the environment sensor 30, the water content is sufficiently removed even when the water content of the transfer material P is high. it can.

Further, by taking into consideration the change in the basis weight of the transfer material P, more accurate water removal can be achieved. this is,
This is because the water content of the transfer material P varies depending not only on the mixing ratio but also on the basis weight, and the higher the basis weight, the higher the water content even under the same mixing ratio environment.

In the above embodiment, the grammage detection sensor T is used, but the present invention is not limited to this, and even if only the environment sensor 30 is used without using the grammage detection sensor T, it is similar to some extent. Have the effect of.

Next, another embodiment will be described with reference to FIG.

FIG. 10 shows a preliminary charging device (preliminary charging means) E.
The pre-charging device E is disposed at the position of the registration roller R (FIG. 1) that feeds the transfer material P to the photosensitive drum 1 in the copying device C.

The preliminary charging device E is a backup roller E.
1 and the backup roller E1 has a core metal (stainless steel) 301. The core metal 301 is rotatably supported by the main body of the copying apparatus C.
The outer circumference of is covered with thick-walled cylindrical insulating rubber 302. A preliminary charging roller E2 is arranged below the backup roller E1.
2 has a core metal 303. The cored bar 303 is rotatably supported by the main body of the apparatus and is a cylindrical column made of stainless steel. The core metal 303 has a pre-charged high-voltage power source 305.
Are connected, and are configured to apply a predetermined charging bias to the core metal 303. Also, the core metal 303
A thick conductive layer 306 is coated on the outer periphery of the conductive layer 306. The conductive layer 306 is made of conductive rubber (volume resistance 10 ⁹
-10 ¹⁰ Ωcm).

Next, the control circuit of the charging bias applied to the preliminary charging roller E2 will be described.

As shown in detail in FIG. 11, a CPU 306 is connected to the precharge high-voltage power supply 305, and the CPU 3
ROM 06, RAM 308, temperature sensor 3
0a and the humidity sensor 30b are connected. Then, the CPU 306 is configured to calculate the mixing ratio based on the signals from the temperature sensor 30a and the humidity sensor 30b. Further, the ROM 307 stores the data of the current value of the optimum charging bias with respect to the mixture ratio (FIG. 12), and the CPU 306 calculates the optimum current value based on the calculated mixture ratio. And CPU
306 sends a signal to the precharge high-voltage power supply 305,
An optimum charging bias is applied to the preliminary charging roller E2 from the preliminary charging high voltage power source 305. For this reason, the transfer material P fed to the photosensitive drum 1 by the preliminary charging device E is preliminarily prepared according to the water content of the transfer material P before the transfer charging is performed by the transfer charging device 5 on the photosensitive drum 1. It is charged.

The operation of the above embodiment will be described with reference to FIG.

When the operator presses a switch (not shown), the temperature sensor 30a and the humidity sensor 30b are activated, and the detected data are transmitted to the CPU 306 (S).
11). Then, the CPU 306 calculates the mixing ratio based on the transmitted data (S12). Next, the CPU 306
Calculates the charging bias (optimum value) applied to the preliminary charging roller E2 based on the calculated mixing ratio and the data stored in the ROM 307 (S13). Further, the CPU 306 sends a signal to the preliminary charging high-voltage power source 305 to control the output voltage of the preliminary charging high-voltage power source 305 (S14), and applies a charging bias to the core metal 303 of the preliminary charging roller E2 (S15).

On the other hand, when one of the feeding rollers 15 and 16 is activated, the transfer material P is loaded into the cassettes K1 and K.
2 is discharged and fed to the preliminary charging device E. The pre-charging device E is activated in synchronization with the rotation of the photosensitive drum 1 as described above, and pre-charges the transfer material P while feeding the transfer material P further downstream.

As a result, even if the water content (mixing ratio) of the transfer material P is large and a part of the charges applied to the transfer material P from the transfer charging device 5 escapes, the preliminary charging device E can be used.
Compensates for the lack of charge.

Therefore, the toner image on the photosensitive drum 1 can be satisfactorily transferred onto the transfer material P regardless of the water content of the transfer material P.

Further, since the pair of rollers are provided with the function of the preliminary charging and the original function of the resist roller, space saving and cost reduction can be achieved.

Although a charging roller is used for the preliminary charging, a corona charger or a conductive fiber may be used instead. In that case, charging is performed on the conveyance path other than the position of the registration roller. Further, in the above embodiment, various functions are incorporated in the registration roller, but this is for space saving and cost reduction, and a dedicated roller for controlling the transfer material may be provided.

The curling, heating of the transfer material, and preliminary charging described above are for so-called single-sided copying, but may be applied for second-sided copying of double-sided copying or multiplex copying.

[0079]

As described above, according to the present invention,
Since the transfer material is subjected to a certain treatment according to the amount of water contained in the transfer material, the transfer material is separated from the image carrier or the toner image formed on the image carrier is transferred. Is done properly. Therefore, it is possible to stabilize the image formed on the transfer material or prevent the transfer material from being defectively conveyed.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the structure of a copying apparatus according to the present invention.

FIG. 2 is a vertical cross-sectional view showing the structure of a registration roller (curl imparting means) R.

FIG. 3 is a block diagram of a temperature setting circuit M.

FIG. 4 is a diagram showing a method of obtaining a target value of a heating roller surface temperature.

5 is a flowchart showing the operation of the temperature setting circuit M. FIG.

FIG. 6 is a vertical cross-sectional view showing the structure of a transfer material moisture removing device.

FIG. 7 is a diagram showing a relationship between a heating roller surface temperature (optimum value) and a basis weight of a transfer material.

FIG. 8A is a perspective view showing a configuration of a grammage detection sensor,
FIG. 6B is a diagram showing the position of the detection lever when the transfer material is not being fed, and FIG. 6C is a diagram showing the position of the detection lever when the transfer material is being fed.

FIG. 9 is a diagram showing the relationship between pressure sensor output and basis weight.

FIG. 10 is a vertical sectional view showing the structure of a preliminary charging device.

FIG. 11 is a block diagram showing a charging bias control unit.

FIG. 12 is a diagram showing a relationship between a charging bias current value and a mixing ratio.

FIG. 13 is a flowchart showing control of charging bias.

FIG. 14 is a vertical sectional view showing the structure of a conventional copying apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier (photosensitive drum) 2 Primary charging device 5 Transfer charging means (transfer charging device) 6 Separation charging means (separation charging device) 30 Detecting means (environmental sensor) 30a Detecting means (temperature sensor) 30b Detecting means (humidity sensor) ) 106 roller heating means (halogen heater) 109 thermistor 110 CPU 111 ROM 115 temperature control circuit 202 detection lever 206 pressure sensor 303 core metal 305 preliminary charging high-voltage power supply 306 CPU 307 ROM D image forming unit E preliminary charging means (preliminary charging device) E1 Backup Roller E2 Preliminary Charging Roller J1, J2 Guide Plate M Temperature Setting Circuit Q Transfer Material Heating Means (Moisture Removal Device) R Curl Applying Means (Registration Roller) R2 Heating Roller T Detection Means (Basis Weight Detection Sensor)

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[Procedure amendment]

[Submission date] December 7, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 6]

[Figure 7]

[Figure 3]

[Figure 4]

[Figure 5]

[Figure 10]

[Figure 8]

[Figure 9]

FIG. 11

[Fig. 12]

[Fig. 13]

FIG. 14

Claims (9)

[Claims] 1. An image carrier on which a toner image is formed, transfer charging means for transferring the toner image on the image carrier to a transfer material, and separation for removing the charge on the transfer material on which the toner image is transferred. In an image forming apparatus including a charging unit, a detection unit that directly or indirectly detects the amount of water contained in the transfer material, and at least one of separation and transfer of the transfer material is appropriate. As is performed, a transfer material pre-processing unit that performs a certain process on the transfer material before transferring the toner image, and a control unit that controls the transfer material pre-processing unit based on a signal from the detection unit. An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein the detection unit includes a humidity detection device that detects the humidity of the atmosphere around the transfer material. 3. The detection means comprises a temperature detection device for detecting the temperature of the atmosphere around the transfer material, and the control means is based on the detection results from the humidity detection device and the temperature detection device. The image forming apparatus according to claim 2, wherein the amount of water contained in the transfer material is calculated. 4. The image forming apparatus according to claim 3, wherein the transfer material pretreatment means is a curl imparting means for curling the transfer material. 5. The curl imparting means has a pair of rollers, and one roller has a roller heating means.
The image forming apparatus according to claim 4, wherein the control unit controls the temperature of the roller heating unit. 6. The image forming apparatus according to claim 3, wherein the transfer material pretreatment means is a transfer material heating means for heating the transfer material from both sides. 7. The transfer material heating means has a pair of rollers, each of these rollers has a roller heating means, and the control means controls the roller heating means. The image forming apparatus according to claim 6, which is characterized in that. 8. The image forming apparatus according to claim 3, wherein the transfer material pretreatment means is a preliminary charging means for charging the transfer material. 9. The detection means includes a basis weight detection device for detecting an amount corresponding to the thickness of one transfer material, and the control means includes the humidity detection device, the temperature detection device, and Based on the detection result from the basis weight detection device,
The image forming apparatus according to claim 3, wherein the amount of water contained in the transfer material is calculated.