JPH04293071A - Electrostatic recorder - Google Patents

Abstract

PURPOSE:To prevent a phenomenon that a transfer sheet is wound around a photosensitive body from occurring and to prevent the jamming of a paper from occurring. CONSTITUTION:A means 10 which remedies an acutest part such as a burr or a curl at the leading edge of the transfer sheet 6 is provided, or air discharge generated in a gap between the leading edge of the sheet 6 and a dielectric belt 2 by the acutest part is reduced by giving electric charge whose polarity is reverse to the electric charge given to a dielectric belt to the belt 2 by an electrostatic charger 3, or the belt 2 is constituted of plural layers and the layer which is brought into contact with the sheet 6 is constituted of an elastic body whose hardness is lower than the sheet 6 and the gap is prevented from being substantially formed between the sheet 6 and the dielectric body by sinking the acutest part of the leading edge of the sheet 6 in the belt 2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic recording device using a dielectric belt, and more particularly to an electrostatic recording device suitable for preventing a transfer sheet from wrapping around a recording medium.

0002

2. Description of the Related Art A conventional toner image transfer device, as described in Japanese Patent Application Laid-open No. 57-27286, has a dielectric belt which is placed on a toner image formed on a recording medium via a transfer sheet. In an apparatus for transferring the toner image onto the transfer sheet by bringing the surfaces into contact and applying a charge to the back surface of the dielectric belt, a constant current is connected to the means for applying a charge to the back surface of the dielectric belt. has been proposed.

[0003] Conventionally, in an electrostatic recording device using the above transfer device, for example, as shown in FIG. When a light pattern is irradiated by an exposure system 18 using a laser optical system, an LED, or an LCD, an electrostatic latent image is formed on the photoreceptor drum 1. Next, when the photosensitive drum 1 passes through the developing device 19, a toner image 23 corresponding to the latent image is formed on its surface. On the other hand, the transfer sheet (paper) 6 is held on the dielectric belt 2, and when it reaches the upper part of the charger 3, which is a means for applying electric charge to the dielectric belt 2, the toner image 23 is transferred to the transfer sheet 6 due to the electric charge. Afterwards, it is fixed on the dielectric belt 6. A cleaning system 25 removes paper dust, dirt, etc. from the surface of the dielectric belt 6. Further, after the surface charge of the photosensitive drum 1 is removed by the erase lamp 7, residual toner, paper dust, etc. on the surface are removed by the cleaning system 24, and the process of charging, exposing, and developing is repeated again.

0004

SUMMARY OF THE INVENTION As in the prior art described above, a toner image transfer device using a dielectric belt originally conveys a transfer sheet by attracting it to the dielectric belt. However, if the transfer sheet is thin paper or recycled paper and the leading edge area is not printed (there is no toner image), when the transfer sheet is placed on the dielectric belt, the transfer sheet may not touch the photoreceptor after transfer depending on the way it is placed. wrap around (drum wrap)
Development occurred frequently. It tends to occur particularly in low humidity environments.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic recording device that prevents the development of a transfer sheet from being wrapped around a photoreceptor and prevents the occurrence of paper jams.

[0006]

[Means for Solving the Problems] In order to achieve the above object, a first invention provides a dielectric belt that is placed over a toner image formed on a recording medium via a transfer sheet supplied from a hopper. In an electrostatic recording device that transfers the toner image onto the transfer sheet by contacting the dielectric belt and applying an electric charge to the back surface of the dielectric belt, in order to prevent the transfer sheet from wrapping around the recording medium. , at least within a nip area between the recording medium and the dielectric belt, the transfer sheet is oriented such that the sharpest end of the transfer sheet is parallel to the surface of the dielectric belt or toward the recording medium. A correction means is provided before the entrance of the nip area between the recording medium and the dielectric belt.

[0007] In a second aspect of the invention, the transfer sheet correction means is constituted by a pair of correction rollers.

[0008] In a third aspect of the present invention, one of the pair of correction rollers is configured to have a smaller diameter than the other correction roller.

[0009] According to a fourth aspect of the present invention, a large number of protrusions are provided on a part of the surface of at least one of the pair of correction rollers.

According to a fifth aspect of the present invention, one of the pair of correction rollers is made of an elastic roller, and the other correction roller is made of a metal roller.

A sixth aspect of the present invention is that one of the pair of correction rollers is provided with means for applying an electric charge having a characteristic opposite to that applied to the back surface of the dielectric belt.

[0012] In a seventh aspect of the invention, one of the pair of correction rollers is configured to apply a pressing force between the pair of correction rollers in response to changes in the type, thickness, and environment of the transfer sheet. A pressure control section is provided to control the pressure.

In an eighth aspect of the present invention, the pressure control section is provided with means for retracting at least one of the correction rollers from the other correction roller when the electrostatic recording apparatus is stopped.

In a ninth aspect of the present invention, the pressure control section stores the pair of correction rollers when the electrostatic recording device is operated, and when the electrostatic recording device operates, the pair of correction rollers are stored in the memory. It is equipped with means for controlling the pressing force.

[0015] In the tenth invention, a dielectric belt is brought into contact with the toner image formed on the recording medium via a transfer sheet supplied from a hopper, and an electric charge is applied to the back surface of the dielectric belt. In an electrostatic recording device that transfers the toner image onto the transfer sheet, in order to prevent the transfer sheet from wrapping around the recording medium, a A static eliminating means is provided which applies a charge of opposite polarity to the charge and reduces air discharge generated in the gap between the transfer sheet and the dielectric belt.

[0016] In the eleventh invention, a dielectric belt is brought into contact with the toner image formed on the recording medium via a transfer sheet supplied from a hopper, and an electric charge is applied to the back surface of the dielectric belt. Accordingly, in an electrostatic recording device that transfers the toner image onto the transfer sheet, in order to prevent the transfer sheet from wrapping around the recording medium, the dielectric belt is configured with a plurality of layers, and The layer on the side in contact with the transfer sheet is made of an elastic material having a hardness lower than that of the transfer sheet, and the sharpest part of the leading edge of the transfer sheet is connected to the dielectric layer between the time the transfer sheet enters the nip region and the time it exits the nip region. The transfer sheet is recessed into the body belt so that substantially no gap is created between the transfer sheet and the dielectric belt.

[0017] In the twelfth invention, a dielectric belt is brought into contact with the toner image formed on the recording medium via a transfer sheet supplied from a hopper, and an electric charge is applied to the back surface of the dielectric belt. Accordingly, in an electrostatic recording device that transfers the toner image onto the transfer sheet, in order to prevent the transfer sheet from wrapping around the recording medium, there is a gap between the photoreceptor of the recording medium and the dielectric belt. A lamp is provided before the nip entrance for irradiating the surface of the photoreceptor to reduce the charge on the photoreceptor.

[0018] In the thirteenth invention, a dielectric belt is brought into contact with the toner image formed on the recording medium via a transfer sheet supplied from a hopper, and an electric charge is applied to the back surface of the dielectric belt. In an electrostatic recording device that transfers the toner image onto the transfer sheet, in order to prevent the transfer sheet from wrapping around the recording medium, the transfer sheet is arranged such that the sharpest end thereof is formed on the dielectric material. It is stored in the hopper so as to face upward with respect to the surface of the belt.

[0019]

[Operation] In order to understand the development process in which the transfer sheet wraps around the photoreceptor drum, we collected the transfer sheets wrapped around the photoreceptor drum and observed the shape of the leading edge of the transfer sheet under a microscope.
It turns out that there is one thing in common.

The reason is that the burrs generated when cutting the transfer sheet are large, and when the transfer sheet is held on the belt surface with the burr (the sharpest part) facing the dielectric belt surface side, winding occurs. That is, as shown in FIG. 9, when the burr 13 at the leading end of the transfer sheet 6 is held facing the surface of the dielectric belt 2, a slight gap 27 is generated between the transfer sheet 6 and the dielectric belt 2. . This gap 27 is generally sealed in the conveying direction of the transfer sheet 6, and its size varies depending on the type of transfer sheet 6, but the gap length γ is 5.
~100 μm, and the width l is approximately 0.5 to 5 mm. The gap 27 reduces the adhesion force between the transfer sheet 6 and the dielectric belt 2. The following two points are considered to be the cause of this.

(i) If the charge given to the dielectric belt 2 by the charger 3 is Q1 (coulomb/cm2), and the polarized charge induced on the transfer sheet 6 by the charge Q1 is -Q2 (coulomb/cm2), then , the attraction force F1 acting between the two is F1 α-Q1 ・Q2 /γ2
becomes. At the tip of the transfer sheet 6, γ is 5 to 100 μm.
Therefore, the suction force F1 becomes smaller and the transfer sheet 6
The force of adsorption to the dielectric belt 2 decreases. As a result,
The force with which the transfer sheet 6 attracts the photoreceptor drum 1 becomes greater, and the transfer sheet 6 wraps around the photoreceptor surface of the photoreceptor drum 1.

(ii) The charger 3 charges the dielectric belt 2
When the electric charge Q1 applied to becomes large, an air discharge occurs in the air gap 27. Among the discharge charges generated by this, the positive polarity charge Q3 (coulomb/cm2) is
The apparent charge on the dielectric belt 2 side of the transfer sheet 6 that is injected into the transfer sheet 6 and contributes to the attraction force with the dielectric belt 2 decreases to -(Q2 - Q3). On the other hand, among the discharge charges, the charge of the negative electrode Q4 (coulomb/cm
2) is injected into the dielectric belt 2, and the electric charge of the dielectric belt 2 that contributes to the adhesion with the transfer sheet 6 is (Q1
-Q4). As a result, the force F'1 acting between the transfer sheet 6 and the dielectric belt 2 is F'1 α-(
Q1 - Q4 ) (Q2 - Q3 )/γ2,
The force F'1 is even smaller than the attractive force F1 when no discharge occurs. Therefore, the wrapping of the transfer sheet 6 around the photoreceptor drum 1 becomes more noticeable.

Next, when cutting paper or the like into a predetermined length using the transfer sheet 6, generally, for example, as shown in FIG.
As shown in FIG. 2, a method is implemented in which a plurality of stacked transfer sheets 6 are held on a table 29 and are simultaneously cut by a cutting blade 28. However, in the above method, FIG.
As shown in (b), a burr 13 is generated at the leading end of the transfer sheet 6, and the burr 13 is largest on the uppermost stacked transfer sheet 6.

As described above, as long as the transfer sheet 6 is cut, it is inevitable that burrs 13 will occur at the leading edge, although there may be differences in degree. Further, the leading edge of the transfer sheet 6 may curl depending on the storage condition, and this may cause burrs to form on the transfer sheet 6 between the dielectric belts as shown in FIG.
A void 27 is generated as shown in FIG.

Therefore, the present invention has the following invention in order to prevent the transfer sheet from being wrapped around the photosensitive drum.

[0026] The first aspect of the present invention is that the sharpest part of the transfer sheet, such as a burr, at least in the nip area between the photosensitive drum and the dielectric belt is directed in a direction parallel to the surface of the dielectric belt or in a direction parallel to the surface of the dielectric belt. The transfer sheet is corrected by a transfer sheet correction means so as to face the body drum, thereby preventing a gap from forming between the transfer sheet and the dielectric belt. Therefore, it is possible to prevent the transfer sheet from wrapping around the photoreceptor drum, and to obtain high reliability without jamming.

[0027] In a second aspect of the present invention, the transfer sheet correction means is constituted by a pair of correction rollers, and the rotation of the pair of correction rollers generates a force that bends the leading end of the transfer sheet inserted between them upward. In response to this, the sharpest part of the tip is crushed. Therefore, with a simple configuration, it is possible to prevent a gap from forming between the transfer sheet and the dielectric belt.

[0028] In a third invention, the diameter of one of the correction rollers in the second invention is configured to be smaller than the diameter of the other correction roller, and a peripheral speed difference is generated between the two correction rollers, so that the leading edge of the transfer sheet is It corrects sharp parts.

[0029] In a fourth invention, a large number of protrusions are provided on a part of the surface of at least one of the correction rollers in the second invention, and there is a gap between the protrusions and the surface of the other correction roller. This is to more efficiently correct the sharpest part of the leading edge of the transfer sheet.

[0030] A fifth invention is the second invention, wherein one of the straightening rolls is made of an elastic material such as rubber, and the other straightening roll is made of a metal roller such as stainless steel.
The leading edge of the transfer sheet is corrected more efficiently by applying a pressing action and a sliding action to the leading edge of the transfer sheet between the two straightening rollers.

[0031] In a sixth invention, means is provided for applying a charge of opposite polarity to the charge applied to the back surface of the dielectric belt to one of the correction rollers according to the second invention, and the leading end of the transfer sheet is placed between the two correction rollers. When the transfer sheet is inserted and corrected, the electric charge applied to the leading end of the transfer sheet through the correction roller improves the adhesion between the transfer sheet and the dielectric belt.

[0032] In a seventh invention, the pressure control section provided on the other correction roller according to the sixth invention adjusts the pressure in response to changes in the type of transfer sheet, such as thickness, and changes in the environment, such as changes in temperature and humidity. It controls the pressing force between a pair of correction rollers.

[0033] In an eighth invention, when the electrostatic recording apparatus is stopped, at least one of the correction rollers is retracted from the other correction roller by the pressure control section provided on the other correction roller in the sixth invention, and the correction is performed. This prevents the rollers and transfer belt from deteriorating.

[0034] In a ninth invention, the pressing force between the two correction rollers during operation of the electrostatic recording device is stored by the storage means provided in the pressure control section according to the seventh invention, and the electrostatic storage device When the apparatus changes from a rest state to an operating state, both correction rollers are controlled to the pressing force stored in the storage means. Therefore, the pressing force between the two correction rollers can be easily set to an appropriate value.

[0035] In the tenth aspect of the present invention, the charge between the transfer sheet and the dielectric belt is removed by a static eliminator that is arranged in parallel with the charger and applies a charge of opposite polarity to the charge applied to the dielectric belt by the charger. This reduces the air discharge that occurs in the void. Therefore, even if a gap occurs, the transfer sheet can be prevented from wrapping around the photoreceptor drum.

[0036] In the eleventh invention, the dielectric belt is composed of a plurality of layers, and the layer on the side in contact with the transfer sheet is composed of an elastic body having a lower hardness than the transfer sheet, so that the transfer sheet does not enter the nip area. The sharpest part of the leading edge of the transfer sheet is recessed into the dielectric belt from the time the transfer sheet is transferred to the time it comes out, so that there is virtually no gap between the transfer sheet and the dielectric belt. Therefore, even if the transfer sheet has the sharpest point at its leading edge, it is possible to prevent a gap between the transfer sheet and the dielectric belt.

In the twelfth invention, the surface of the photoreceptor drum is formed of a photoreceptor, and the surface of the photoreceptor is irradiated with lamp light before the nip entrance between the photoreceptor and the dielectric belt, so that the photoreceptor is This reduces the charge on the transfer sheet, thereby making it possible to prevent the transfer sheet from wrapping around the photoreceptor drum.

[0038] In the thirteenth invention, when storing the transfer sheet cut into a predetermined size in advance in the hopper,
The tip of the transfer sheet is stored so that the sharpest part faces upward with respect to the surface of the dielectric belt, and the sharpest part prevents a gap from forming between the transfer sheet and the dielectric belt.

[0039]

[Embodiment] FIG. 1(a) is an explanatory diagram showing an electrostatic recording apparatus which is an embodiment of the present invention, and FIG. 1(b) shows the transfer sheet correction means and transfer sheet guide shown in FIG. 1(a). It is an enlarged view of a presser guide part.

As shown in both figures, the dielectric belt 2 is suspended under a constant tension by one driving roller 8 and two driven rollers 7a, 7b, and the surface thereof is , the transfer sheet 6 onto which the toner image is transferred by the photoreceptor drum 1 is held and transported. Further, the dielectric belt 2 is connected to a constant current power source (not shown) on the reflective side of the transfer position on the back side thereof, and has a charger 3 that charges the dielectric belt 2, and a charger 3 on both sides of the charger 3. Two rollers 4 and 5 are provided for pressing the dielectric material 2 against the photoreceptor drum 1 and securing a nip area. Note that it is also possible to omit one of the rollers 4 and secure a nip area between the other roller 5 and the driven roller 7a.

The transfer sheet correction means 10 corrects the transfer sheet 6.
Two correction rollers 11a, 1 that nip from the top and bottom directions
1b, and each rotates in the direction of the arrow by a drive source (not shown). The transfer sheet guide means 9 is disposed on the transfer sheet supply side of the transfer sheet correction means 10, and is formed symmetrically in the vertical direction of the transfer sheet 6 in order to supply the leading end of the transfer sheet 6 to the transfer sheet correction means 10. It is composed of two transfer sheet guide plates 9a and 9b. In order to insert the transfer sheet 6 into the nip area between the photoreceptor drum 1 and the dielectric belt 2, the guide presser guide 9c has its tip end located near the entrance of the nip area. Note that it is desirable that the guide presser guide 9c be in contact with the dielectric belt. As a result, the transfer sheet 6 moves against the guide presser guide 9c, thereby producing the effect of correcting burrs at the leading end of the transfer sheet 6.

Next, at the leading end of the transfer sheet 6, for example, as shown in FIG.
A method for correcting the tip burr 13 of the transfer sheet 6 on which the burr 3 is formed will be explained with reference to FIGS. 1(a) and 1(b).

The transfer sheet 6 is supplied, and its leading edge is 2
When the transfer sheet 6 is guided by the two transfer sheet guide plates 9a and 9b and nipped between the two correction rollers 11a and 11b, the burr 13 at the leading end of the transfer sheet 6 receives an upward bending force. As a result, the burr 13 is crushed. In this case, for example, even if the burr 13 is small, if there is a downward curl, the two correction rollers 11a and 11b exert a reverse curling effect, so that this can be eliminated. Therefore, the sharpest end of the transfer sheet 6 is corrected so that it is parallel to the surface of the dielectric belt 2 or faces toward the photosensitive drum 1.

Note that the upper straightening roll 11a is made of an elastic material such as a rubber roll, and the lower straightening roll 11b is made of metal such as stainless steel to form a nip between the two straightening rolls 11A and 11b. Thereby, the effect of straightening the leading end of the transfer sheet 6 can be further improved by the pressing action and the rubbing action of the leading end of the transfer sheet 6. Further, as shown in FIG. 2, one of the above-mentioned straightening rolls 11
By forming a large number of protrusions 11c on a part of the outer peripheral surface of a or 11b, the pressing force and sliding force of the protrusions 11c are increased, so that the correction effect can be further improved. In addition, the straightening effect is further improved by making the diameter of the upper straightening roll 11a smaller than the diameter of the lower straightening roll 11b (see FIG. 3) and creating a difference in circumferential speed between the two straightening rolls 11a and 11b. can do. Further, in the embodiment shown in FIG. 3, the power source 12 is connected to the lower straightening roll 11b, and the upper straightening roll 1
A pressure control section 32 is connected to 1a. Above power supply 12
An electric charge having a polarity opposite to that applied to the back surface of the dielectric belt 2 by the charger 3 is applied to at least the leading end of the transfer sheet 6 via the lower correction roll 11b. Although not shown, the pressure control section includes a means for determining the type of transfer sheet 6, such as its thickness, a means for detecting temperature and humidity, and a means for determining the thickness, temperature and humidity of transfer sheet 6 through experiments or the like in advance. It is comprised of a means for setting data related to pressure and calculating a pressing force based on the results of the thickness determining means and temperature/humidity detecting means. Therefore,
According to the embodiment shown in FIG. 3, a pair of correction rollers 11a,
A voltage is applied between the rollers 11b to apply an electric charge to at least the transfer sheet 6 at the same time as the straightening process, and the pressing force of both the straightening rollers 11a and 11b is changed depending on the type of the transfer sheet 6 and the environment, thereby further improving the straightening effect. can do. Note that the two transfer sheet guide plates 9a, 9
The initial charge on the transfer sheet 6 may be removed by setting b to the ground potential.

When the transfer sheet 6 with the burr 13 at the leading edge corrected in this manner reaches the leading end of the guide presser guide 9c while being held on the surface of the dielectric belt 2, the transfer sheet 6 is held on the surface of the dielectric belt 2 and reaches the tip of the guide presser guide 9c. dielectric belt 2 at the tip of
The dielectric belt 2 is inserted between the surface of the dielectric belt 2 and the photosensitive drum 1 while being pressed against the surface of the dielectric belt 2 . Therefore, it is possible to eliminate the gap formed between the lower surface of the leading end of the transfer sheet 6 and the surface of the dielectric belt 2 due to burrs or curls at the leading end of the transfer sheet 6, and thereby the transfer sheet 6 is attached to the photoreceptor drum 1. It is possible to prevent development from wrapping around. Furthermore, in addition to this, the above effect can be improved by applying an electric charge to the leading end of the transfer sheet 6.

Next, FIG. 4(a) showing an electrostatic recording apparatus according to another embodiment of the present invention will be described. Figure 4 (a
), a pair of correction rollers 14,1
5 are arranged in the vertical direction with the dielectric belt 2 in between, and the diameter of the upper correction roller 14 is formed smaller than the diameter of the lower correction roller 15, so that there is a difference in circumferential speed between the two correction rollers 14 and 15. are doing. In addition, a voltage is applied between the two correction rollers 14 and 15 to give the transfer sheet 6 an electric charge of opposite polarity to the electric charge applied to the back surface of the dielectric belt 2 by the charger 3. A pressure control section 32 is connected to the above-mentioned upper correction roller 14 that improves the attraction force between the transfer sheet 6 and the dielectric belt 2. Although not shown, the pressure control section 32 includes means for detecting the pressing force between the two correction rollers 14 and 15, and means for storing the pressing force detected by the pressing force detecting means during operation of the electrostatic recording device. and means for retracting at least one of the correction rollers 14 or 15 when the electrostatic recording device is inactive, and for making the pressing force between the two correction rollers 14 and 15 stored in the storage means when the electrostatic recording device is in operation. It is composed of. A constant current power source 16 is connected to the charger 3. Further, a static eliminator 17 is arranged in parallel with the charger 3, and a power source 18 is connected to the static eliminator 17. The power source 18 supplies the static eliminator 17 with an electric charge having a polarity opposite to that of the AC power source or the power source 16 described above. Therefore, the charge applied to the dielectric belt 2 by the charger 3 is reduced, thereby reducing the gap between the back surface of the transfer sheet 6 and the front surface of the dielectric belt 2 as explained in FIG.
It is possible to reduce the electric field acting on 7 and prevent air discharge from occurring. In this case, the static electricity needs to be eliminated only at the leading edge of the transfer sheet 6, so for example, by detecting that the leading edge of the transfer sheet 6 has touched the static eliminator 17 and controlling the static neutralizing current value, selective static neutralizing is performed. be able to. In addition, the static eliminator 17 can be installed at the nip outlet,
The transfer point is selected between the transfer points (approximately corresponding to the mounting position of the charger 3). Furthermore, since at least one of the correction rollers 14 or 15 is retracted by the pressure control section 32 when the electrostatic recording apparatus is stopped, deterioration of the correction rollers 14, 15 and the transfer belt 2 can be prevented.

Next, a description will be given of FIGS. 4(b) and 4(c) showing another embodiment of the static eliminating means. The static eliminating means shown in FIG. 4(b) is composed of a roller 19 and a power source 18,
The static eliminating means shown in FIG. 4(c) includes a conductive brush 20 and a power source 18. The power source 18 is the charger 3
When a positive charge is given to the dielectric belt 2 by , a charge of negative polarity is given to the dielectric belt 2 . Therefore, this embodiment also has the same effect as that of FIG. 4(a).

Next, FIG. 5 shows another embodiment of the present invention.
I will explain about it.

In the embodiment shown in FIG.
The transfer sheet 6 is brought into close contact with the surface of the dielectric belt 2 to prevent a gap from forming between the transfer sheet 6 and the dielectric belt 2.

As shown in FIG. 5, the dielectric belt 2 is composed of three layers, and the lower layer 2c facing the charger 3 includes:
It is made of a material with excellent corona resistance, such as PVDF (polyvinylidene fluoride) or a fluorine-based material. The intermediate layer 2b is made of a material that has mechanical strength and flexibility as a conveyor belt. That is, for flexibility, it is formed of a rubber-based material such as urethane rubber, chloroprene rubber, or elastomer, and for mechanical strength, it is made thicker than the other layers 2a and 2c. For example, the upper layer 2a and the lower layer 2c are usually several tens of μm to 100 μm.
m, whereas the intermediate layer 2b has a thickness of 100 to 500 μm. On the other hand, as shown in FIG. 5(b), the upper layer 2a in contact with the recording medium and the transfer sheet 6 has burrs 13 and the like at the leading end of the transfer sheet 6 sinking into the upper layer 2a in the nip area, and is substantially The transfer sheet 6 is made of a soft elastic material such as urethane rubber or foamed urethane so that no gap is formed between the lower surface of the transfer sheet 6 and the surface of the dielectric belt 2 .

Therefore, this embodiment is particularly effective when the transfer sheet 6 is a hard sheet such as an OHP sheet.

Next, FIG. 6 showing still another embodiment of the present invention will be described.

The embodiment shown in FIG. 6 prevents the transfer sheet from wrapping around the photosensitive drum.

The wrapping of the transfer sheet 2 around the photoreceptor drum 1 is caused by the attraction force between the charges on the transfer sheet 6 and the charges on the photoreceptor drum 1. Although FIG. 4 shows a method of reducing the charge on the transfer sheet 2, this embodiment conversely reduces the charge on the photosensitive drum 1. Therefore, lamp 2
1 is provided at one of the positions 21a, 21b, and 21c. That is, when the toner image transfer position is A, light is irradiated at an intermediate point B before the leading edge of the transfer sheet 6 passes through A and reaches the nip exit C so as to reduce the charge on the photoreceptor drum 1. In this case, the optical response of the photoreceptor drum 1 generally has time dependence, as shown in FIG. 6(b).
As shown in 21a, it is installed near the nip entrance, and
If the nip portion between the photoreceptor drum 1 and the dielectric belt 2 is irradiated from the position 1a, the surface potential of the photoreceptor drum 1 V0
The photosensitive drum 1 passes through the intermediate point B in a state where the voltage has decreased to a sufficiently small value (for example, 50 V or less). Furthermore, in the case where the photoreceptor drum 1 has a structure in which a transparent conductive film is formed on the surface of a glass tube and a photoreceptor is formed on it,
As shown at 21b, the light may be irradiated from the inside of the photoreceptor drum to the outside. Furthermore, when the dielectric belt 2 is transparent, light can be irradiated from the back side of the dielectric belt 2, as shown at 21c. The irradiation area of the photoreceptor surface of the photoreceptor drum 1 is as shown in FIG. 6(c).
The area 22 near the front and back of the leading end of the transfer sheet 6 may be used. Therefore, in this embodiment, even if a burr 13 or the like is formed at the leading edge of the transfer sheet 2 and there is a gap between the lower surface of the transfer sheet 2 and the surface of the dielectric belt 2, the transfer sheet 2 is not easily attached to the photoreceptor drum 2. It can prevent it from getting wrapped around.

Next, FIG. 7, which shows a hopper as an embodiment of the present invention, will be described.

As shown in FIG. 7(a), the transfer sheet 6 is cut into a predetermined size in advance and placed in the hopper 30.
The transfer sheets 6 are stored in a vertically stacked manner and are sequentially conveyed to the electrostatic recording apparatus by a conveyance member 31 starting from the uppermost transfer sheet 6. However, as explained with reference to FIG. 10, the transfer sheet 6 is cut by the cutting blade in such a way that it is pushed through, so that many burrs 13 are generated on the same side, as shown in FIG. 10(b).

Therefore, in this embodiment, the transfer sheet 6 is stored in the hopper 30 by single-sided printing or double-sided printing as follows.

(a) In the case of single-sided printing, at least the sharpest part 13 of the transfer sheet 6 due to the edge burr etc. shown in FIG.
As shown in (b), the hopper 30 is facing upward.
Alternatively, as shown in FIG. 7(c), the hopper 30 is stored with the side where the sharpest portion 13 is located opposite to the conveyance direction.

(b) In the case of double-sided printing, the transfer sheet 6 is
It is reversed at the switchback section so that the front and back are reversed from when printing on the first side. Therefore, as shown in FIG. 7C, the paper is stored in the hopper 30 so that the side where the sharpest part 13 is present is on the opposite side to the conveyance direction. therefore,
Since no gap is generated between the dielectric belt and the transfer sheet 6 in the nip area between the photoreceptor drum and the dielectric belt, the transfer sheet 6 after transfer is prevented from wrapping around the photoreceptor drum. Can be done.

[0060] In the above embodiment, mainly:
It shows the sharpest part due to burrs, curls, etc.
The invention is not limited to this, and can be applied, for example, to cases where the transfer sheet is bent and a gap is created between it and the dielectric belt.

[0061]

According to the first aspect of the invention, at least in the nip area between the transfer sheet and the photosensitive drum and the dielectric belt, the sharpest part such as a burr on the leading edge of the transfer sheet is removed from the dielectric belt. The transfer sheet correction means installed in front of the entrance of the nip area in a direction parallel to the surface or toward the photoconductor drum corrects burrs on the leading edge of the transfer sheet, so that there is no space between the transfer sheet and the dielectric belt. , it is possible to prevent the generation of voids. Therefore, it is possible to prevent the transfer sheet from wrapping around the photoreceptor drum, and it is possible to obtain high reliability without jamming.

According to the second aspect of the invention, since the transfer sheet correction means is constituted by a pair of correction rollers, the leading end of the transfer sheet inserted between them is bent upward by the rotation of the pair of correction rollers. The sharpest part of the tip is crushed by the force applied. Therefore, it is possible to prevent a gap from forming between the transfer sheet and the dielectric belt with a simple configuration.

According to the third invention, since one of the pair of correction rollers is configured to have a smaller diameter than the other correction roller, a difference in circumferential speed occurs between the pair of correction rollers. The sharpest part at the leading edge of the transfer sheet can be corrected more efficiently.

According to the invention shown in FIG. 4, a large number of projections are provided on a part of the surface of at least one of the pair of correction rollers, so that the projections and the other correction roller are connected to each other. The sharpest part of the leading edge of the transfer sheet can be corrected more efficiently.

According to the invention shown in FIG. 5, one of the pair of correction rollers is made of an elastic material such as rubber, and the other correction roller is made of a metal roller such as stainless steel. Therefore, according to the sixth invention, the leading edge of the transfer sheet can be straightened more efficiently by applying a pressing action and a sliding action to the leading edge of the transfer sheet between the two straightening rollers. Since one of the correction rollers is provided with means for applying an electric charge of opposite polarity to the electric charge applied to the back surface of the dielectric belt, when the leading edge of the transfer sheet is inserted between the pair of correction rollers and is corrected, the correction roller Due to the electric charge given to the leading edge of the transfer sheet through
Adhesion between the transfer sheet and the dielectric belt can be improved.

According to the seventh invention, one of the pair of correction rollers may be subjected to correction due to a change in the type of the transfer sheet, such as a change in thickness, or a change in the environment, such as temperature and humidity. Since the pressure control unit is provided to control the pressing force between the rollers, it is possible to set the optimum pressing force between the pair of correction rollers in response to changes in the type of transfer sheet and the environment.

According to the eighth invention, one of the pair of correction rollers is provided with a pressure control section for retracting at least one of the correction rollers from the other correction roller when the electrostatic recording apparatus is stopped. Therefore, deterioration of the correction roller and transfer belt can be prevented.

According to the invention shown in FIG. 9, the pressure control section of the eighth invention stores the pressing force between the pair of correction rollers during operation of the electrostatic recording device, and Time,
Since the storage means for controlling the stored pressing force is provided, the pressing force between the pair of correction rollers can be easily set to an appropriate value when the electrostatic recording device is operated.

According to the tenth aspect of the present invention, since the transfer sheet is provided with a charge eliminating means for applying a charge having a polarity opposite to the charge applied to the transfer sheet back surface, the transfer sheet and
Air discharge occurring in the gaps between the dielectric belts can be reduced, thereby preventing the transfer sheet from wrapping around the recording medium even if gaps occur.

According to the eleventh invention, the dielectric belt is composed of a plurality of layers, and the layer on the side in contact with the transfer sheet is composed of an elastic body having a lower hardness than the transfer sheet, so that the transfer The sharpest part of the leading edge of the transfer sheet sinks into the dielectric belt from the time the sheet enters the nip region until the sheet exits the nip region, so that substantially no gap is created between the transfer sheet and the dielectric belt. be able to.

According to the twelfth aspect of the invention, since a lamp is provided that irradiates the surface of the external photoreceptor before the entrance of the nip between the photoreceptor formed on the surface of the recording medium and the dielectric belt, the charge on the photoreceptor is reduced. It is possible to prevent the transfer sheet from wrapping around the surface of the photoreceptor.

According to the thirteenth invention, when storing the transfer sheet cut to a predetermined size in the hopper, the sharpest part of the leading edge of the transfer sheet faces upward with respect to the surface of the dielectric belt. Since the transfer sheet is stored in this manner, it is possible to prevent the formation of a gap between the transfer sheet and the dielectric belt due to the sharpest part.

[Brief explanation of the drawing]

FIG. 1(a) shows an electrostatic recording device according to an embodiment of the present invention, and FIG. 1(b) is an enlarged view showing a transfer sheet correcting means and a transfer sheet guiding/pressing guide portion thereof.

FIG. 2 is a diagram showing a transfer sheet correction means according to another embodiment of the present invention.

FIG. 3 is a diagram showing a transfer sheet correction means according to another embodiment of the present invention.

FIG. 4(a) shows an electrostatic recording device as another embodiment of the present invention, and FIGS. 4(b) and 4(c) each show other embodiments of static eliminating means.

FIG. 5(a) shows a dielectric belt according to another embodiment of the present invention, and FIG. 5(b) is a diagram showing the relationship between the dielectric belt and a transfer sheet.

FIG. 6(a) shows an electrostatic recording device which is another embodiment of the present invention, (b) shows the surface potential of the photoreceptor drum, and (c) shows the vicinity of the leading edge of the transfer sheet. FIG. 3 is a diagram showing regions.

FIG. 7(a) shows a hopper as an embodiment of the present invention, and FIGS. 7(b) and 7(c) each show an embodiment in which a transfer sheet is stored in the hopper.

FIG. 8 is a diagram showing a conventional electrostatic recording device.

FIG. 9 is an explanatory diagram showing a leading end portion of a transfer sheet in a conventional electrostatic recording device.

FIG. 10 (a) shows when the transfer sheet is cut, (b)
This is a diagram showing the leading edge of the transfer sheet after cutting.

[Explanation of symbols]

1... Recording medium (photosensitive drum), 2... Dielectric belt, 3
... Charger, 4, 5... Roller, 6... Transfer sheet, 9... Transfer sheet guide means, 10... Transfer sheet correction means, 11,
14, 15... Correction roller, 13... Sharpest part (burr, curl), 17... Static eliminator, 21... Lamp, 27... Gap.

Claims (13)

[Claims] 1. A dielectric belt is brought into contact with a toner image formed on a recording medium via a transfer sheet supplied from a hopper, and an electric charge is applied to the back surface of the dielectric belt, thereby transferring the toner image. In an electrostatic recording device that transfers an image onto the transfer sheet, in order to prevent the transfer sheet from wrapping around the recording medium after the transfer sheet leaves the nip area between the recording medium and the dielectric belt, At least within a nip area between the recording medium and the dielectric belt, means for correcting the transfer sheet so that the sharpest part of the leading edge thereof is parallel to the surface of the dielectric belt or toward the recording medium. An electrostatic recording device characterized in that it is provided in front of an entrance to a nip area. 2. The electrostatic recording apparatus according to claim 1, wherein the transfer sheet correction means includes a pair of correction rollers. 3. The electrostatic recording apparatus according to claim 2, wherein one of the pair of correction rollers has a diameter smaller than that of the other correction roller. 4. The electrostatic recording apparatus according to claim 2, wherein the pair of correction rollers includes a plurality of protrusions on a part of the surface of at least one of the correction rollers. 5. The static image forming apparatus according to claim 2, wherein the pair of correction rollers includes one of the correction rollers made of an elastic roller and the other correction roller made of a metal roller. Electric recording device. 6. The pair of correction rollers is characterized in that one of the correction rollers is provided with means for applying a voltage of opposite polarity to the charge applied to the back surface of the dielectric belt. 5. The electrostatic recording device according to 4 or 5. 7. The pair of correction rollers is characterized in that one of the correction rollers is provided with a pressure control section that controls the pressing force between the two correction rollers depending on the type of transfer sheet and changes in the environment. , 3, 4, 5, or 6. 8. The electrostatic recording apparatus according to claim 7, wherein the pressure control section includes means for retracting at least one correction roller from the other correction roller when the electrostatic recording apparatus is stopped. . 9. The pressure control unit stores a pressing force between the correction rollers when the electrostatic recording device is operated, and controls the correction rollers to the stored pressing force when the electrostatic recording device is operated. 9. The electrostatic recording apparatus according to claim 8, further comprising means for controlling. 10. A dielectric belt is brought into contact with the toner image formed on the recording medium via a transfer sheet supplied from a hopper, and an electric charge is applied to the back surface of the dielectric belt to transfer the toner image. In an electrostatic recording device that transfers an image onto the transfer sheet, the transfer sheet may be provided with the above-mentioned method to prevent the transfer sheet from wrapping around the recording medium after the transfer sheet leaves the nip area between the recording medium and the dielectric belt. A charge with a polarity opposite to that applied to the back surface of the transfer sheet is applied to the back surface of the transfer sheet (the surface of the transfer sheet facing the recording medium) to suppress air discharge generated in the gap between the transfer sheet and the dielectric belt. An electrostatic recording device characterized by being provided with a means for eliminating static electricity. 11. A dielectric belt is brought into contact with a sheet image formed on a recording medium via a transfer sheet supplied from a hopper, and an electric charge is applied to the back surface of the dielectric belt to transfer the toner. In an electrostatic recording device that transfers an image onto the transfer sheet, in order to prevent the transfer sheet from wrapping around the recording medium, the dielectric belt is composed of a plurality of layers and is in contact with the transfer sheet. The side layer is made of an elastic material having a lower hardness than the transfer sheet, and the sharpest part of the leading edge of the transfer sheet is inserted into the dielectric belt from the time the transfer sheet enters the nip area until the transfer sheet exits the nip area. An electrostatic recording device characterized in that the transfer sheet is inserted into the dielectric belt so that substantially no gap is formed between the transfer sheet and the dielectric belt. 12. A dielectric belt is brought into contact with the toner image formed on the recording medium via a transfer sheet supplied from a hopper, and an electric charge is applied to the back surface of the dielectric belt, thereby transferring the toner image. In an electrostatic recording device that transfers an image onto the transfer sheet, in order to prevent the transfer sheet from wrapping around the recording medium, a step is provided before the entrance of the nip between the photoreceptor of the recording medium and the dielectric belt. . An electrostatic recording device, comprising a lamp that irradiates the surface of the photoreceptor to reduce the charge on the photoreceptor. 13. A dielectric belt is brought into contact with the toner image formed on the recording medium via the transfer sheet supplied from the hopper, and an electric charge is applied to the back surface of the dielectric belt to transfer the toner image. In an electrostatic recording device that transfers an image onto the transfer sheet, in order to prevent the transfer sheet from wrapping around the recording medium, the transfer sheet is held so that its sharpest tip is against the surface of the dielectric belt. An electrostatic recording device characterized in that the electrostatic recording device is stored in the hopper so as to face upward.