JP3431794B2 - Image forming device - Google Patents

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 used in a laser printer, a copying machine, a laser fax machine, a composite machine thereof, and the like.

[0002]

2. Description of the Related Art A conventional image forming apparatus is disclosed in JP-B-64-8.
No. 331, in order to prevent fatigue deterioration of the image bearing member and to have a stable charging property of the photosensitive member with time and carrier transfer performance of the CTL layer, matching with the sensitivity property of the carrier generation layer of the image carrier or carrier transfer is performed. A light irradiation unit that emits irradiation light in a wavelength range outside the absorption band of the layer is provided, and the disturbance of the surface potential of the photoconductor after transfer by the charger transfer unit is smoothed by recharging and exposing the surface of the photoconductor once. The item to remove the charge was described.

Further, JP-A-1-191168, JP-A-1-191169, and JP-A-1-191172.
In order to prevent toner scattering and dust in the lateral (thrust) direction due to a drop in the background potential of the toner image visualized on the photoconductor, the toner passes after the development process and before the transfer process. It has been described that light having a wavelength is irradiated by a light irradiation means to eliminate the potential of the toner adhering portion (photoreceptor surface) to reduce the potential difference between the toner adhering portion potential and the background portion.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the one disclosed in Japanese Patent No. 331, only the fatigue deterioration of the image carrier is prevented, but the transfer failure due to the decrease of the transfer potential at the time of transfer cannot be prevented.

Further, JP-A-1-191168, JP-A-1-191169, and JP-A-1-191172.
In the publications such as Japanese Patent Publication No. JP-A No. 2003-242, since the light having a wavelength that passes through the magenta and cyan toners is irradiated, the surface layer of the image bearing member (multilayer type photoconductor) becomes cloudy over time and finally used. There was a fear that it would not be possible.

[0006]

SUMMARY OF THE INVENTION An image forming apparatus of the present invention for solving the above-mentioned problems electrically holds a transfer paper and a laminated type image carrier on which a toner image is formed. , By bringing the transfer paper into contact with the image carrier,
And a transfer unit that rotates at a predetermined rotation speed to transfer the toner image formed on the image carrier, the transfer unit including a dielectric layer, a semiconductive layer, and a contact surface of the transfer paper. And a conductor layer are sequentially laminated, and a grounded electrode member is in contact with the surface on the upstream side from the transfer position on the surface of the dielectric layer via a transfer paper, and voltage applying means for applying a predetermined voltage to the conductor layer. When the electricity removing means for neutralizing the dielectric layer, wherein the image forming apparatus having a cleaning means, a to remove residual toner on the dielectric layer, the transfer process of the toner image formed on the image bearing member Upstream and after the development step, the image carrier is provided with a light irradiating means comprising a light emitting element for irradiating light in a wavelength range not absorbed by the carrier moving layer of the image carrier, and the light emitting surface of the light emitting element of the light irradiating means is , The light emitting surface
Prevents light from entering the developing position of the image carrier
In order to irradiate the image bearing member on the side closer to the image bearing member than the extension line of the tangent line from the developing position of the image bearing member.
It is located in .

Further, an image forming apparatus of the present invention for solving the above-mentioned problems has a laminated type image carrier on which a toner image is formed and at least a resistor or a dielectric, and the image carrier And an intermediate transfer unit that rotates at a predetermined rotation speed to transfer the toner image formed on the image bearing member by contacting with the intermediate transfer unit, the intermediate transfer unit charging the surface of the dielectric layer. means and, in the electricity removing means for neutralizing the dielectric layer, an image forming apparatus having a cleaning means, a to remove residual toner on the dielectric layer, the transfer of the toner image formed on the image bearing member step upstream and after the development step of, providing a light irradiation means formed from the light-emitting element which emits light in a wavelength range which is not absorbed in the carrier transport layer of the image bearing member to the image bearing member, the light emitting elements of the light irradiation unit
The light-emitting surface of the child receives light from the light-emitting surface to develop the image carrier.
In order to prevent the image carrier from entering the position, it is on the image carrier side with respect to the extension line of the tangent line from the developing position of the image carrier , and
It is arranged to illuminate the image carrier .

[0008]

[0009]

[0010] described above, in the image forming apparatus of the present invention, as a light-emitting element of the light irradiation unit can be used directional red light emitting element.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic structure of the image forming apparatus of the present invention will be described with reference to FIGS.

As shown in FIG. 2, the image forming apparatus of the present invention stocks and supplies a transfer sheet as a recording sheet on which an image is formed with toner, and a toner image is transferred onto the transfer sheet. Transfer unit 2 and developing unit 3 that forms a toner image
And a fixing unit 4 for fusing and fixing the toner image transferred onto the transfer paper.

In the paper feed unit 1, a paper feed cassette 5 which is removably arranged at the bottom of the main body and which feeds it to the transfer unit 2, and a front face provided on the front side of the main body A manual sheet feeding section 6 for manually feeding the transfer sheets one by one is provided. On the other hand, a pickup roller 7 for feeding the transfer sheets one by one from the uppermost part of the sheet feeding cassette 5,
A PF roller 8 that conveys the transfer paper sent out by the pickup roller 7 and a manual feed roller 9 that conveys the transfer paper from the manual feed supply unit 6 are provided, and the PF roller 8 or the transfer paper conveyed by the manual feed roller 9 is provided. A pre-curl roller 10 that curls the sheet is provided.

The paper feed cassette 5 is provided with a sending member 5a biased upward by a spring or the like, and the transfer paper is stacked on the sending member 5a.
As a result, the uppermost part of the transfer paper in the paper feed cassette 5 contacts the pickup roller 7, and the transfer paper is fed one by one to the PF roller 8 by the rotation of the pickup roller 7 in the direction of the arrow, and is conveyed to the pre-curl roller 10. . On the other hand, the transfer paper supplied from the manual paper feeding unit 6 is also conveyed to the pre-curl roller 10 by the manual paper feeding roller 9.

The pre-curl roller 10 curls the transferred transfer paper as described above, so that the transfer paper is easily attracted to the surface of the cylindrical transfer drum 11 provided in the transfer section 2. This is because

The transfer section 2 is provided with a transfer drum 11 as the above-mentioned transfer means, and around the transfer drum 11, a ground roller 12 as an electrode member installed and a transfer drum 11 are dropped. A guide member 13 that guides the transfer paper so as not to exist, a peeling claw 14 that forcibly peels off the transfer paper attracted to the transfer drum 11, and the like are provided. The peeling claw 14 is provided on the surface of the transfer drum 11 so as to be able to come into contact with and separate from it. The details of the structure of the transfer drum 11 will be described later.

The transfer drum 11 is provided in the developing section 3.
There is provided a photosensitive drum 15 as an image bearing member that comes into pressure contact with the photosensitive drum 15. The photosensitive drum 15 is composed of a grounded conductive aluminum base tube 15a, and an OPC film 15b (FIGS. 9 and 10) on the surface thereof. Has been applied.

Further, around the photosensitive drum 15, developing devices 16, 17, 18 and 19 containing yellow, magenta, cyan and black toners are radially arranged, and the surface of the photosensitive drum 15 is covered. Charger 2 for charging
A cleaning blade 21 for scraping off and removing the residual toner on the surface of the photosensitive drum 15 is provided, and a toner image is formed on the photosensitive drum 15 for each toner. That is, according to the photoconductor drum 15, charging, development, and transfer are repeated for each color.

Therefore, in the case of color transfer, the transfer drum 1 is electrostatically attracted to the transfer drum 11 with respect to the transfer drum 1.
Each time 1 rotates once, a toner image for each color is transferred onto the transfer paper, and one color image is obtained by a maximum of 4 rotations. Incidentally, the photoconductor drum 15 and the transfer drum 11
In terms of transfer efficiency and image quality, a pressure of 8 kg is applied at the transfer site.

In the fixing unit 4, a fixing roller 23 that fuses a toner image at a predetermined temperature and pressure to fix it on a transfer sheet.
And a fixing guide 22 that guides the transfer paper separated from the transfer drum 11 by the separation claw 14 to the fixing roller 23 after the transfer of the toner image. Further, a discharge roller 24 is provided on the downstream side of the transfer paper conveyance of the fixing section 4, and the transfer paper after fixing is discharged from the main body of the apparatus to a discharge tray 25.
It is designed to discharge above.

Now, the structure of the transfer drum 11 will be described.

As shown in FIG. 3, the transfer drum 11 uses a cylindrical conductor layer 26 made of aluminum as a base material, and an upper surface of the conductor layer 26 is made of elastic semi-conductive urethane foam. A body layer 27 is provided. Further, on the upper surface of the semiconductive layer 27, a dielectric layer 28 made of polyvinylidene fluoride is provided. Also,
The conductor layer 26 has a power supply unit 3 as a voltage applying unit.
2 are connected so that the conductor layer 26 can maintain a stable voltage over the entire circumference.

Here, the suction / transfer operation of the transfer paper by the transfer drum 11 will be described below with reference to FIGS. 6 and 7. The conductor layer 26 of the transfer drum 11
It is assumed that a positive voltage is applied from the power supply unit 32 to the.

First, the step of attracting the transfer paper P will be described. As shown in FIG. 6, the transfer paper P conveyed to the transfer drum 11
Is pressed against the surface of the dielectric layer 28 by the ground roller 12, the electric charge accumulated in the semiconductive layer 27 is transferred to the dielectric layer 28, and the electric charge is induced to + on the surface of the dielectric layer 28. As a result, negative charges are induced inside the transfer paper P, that is, on the contact surface side with the dielectric layer 28. As a result, the transfer paper P is electrostatically attracted to the transfer drum 11.
It should be noted that this attraction force does not vary as long as the applied voltage is stable, and the transfer paper P can be stably attracted to the transfer drum 11.

As described above, since the charging is performed by contact instead of charging by air discharge, the conductive layer 26 is used.
The voltage applied to the device is low, and from the results of various experiments, it is appropriate that the applied voltage is +3 kV or less, and more preferably,
If it is +2 kV, good charging can be performed. Further, the transfer paper P attracted to the transfer drum 11 is
In the state where the transfer drum 11 is charged in the direction of the arrow, the toner is conveyed to the transfer point X of the toner image as the transfer drum 11 rotates in the arrow direction.

Next, the transfer process of the transfer paper P will be described. As shown in FIG. 7, the photosensitive drum 15 has toner having negative electric charges adsorbed on its surface. Therefore, the surface is +
When the transfer paper P that has been charged to the point of time is conveyed to the transfer point X, the toner is adsorbed and transferred onto the surface of the transfer paper P due to the potential difference between the positive charge of the surface of the transfer paper P and the negative charge of the toner.

Further, as shown in FIG. 8, the width of the dielectric layer 28 of the transfer drum 11 is larger than the width of the photoconductor tube (aluminum tube 15a) forming the photoconductor drum 15, and The width of the photoconductor tube is larger than the effective transfer width, and the effective transfer width is equal to the effective image width (OPC film 1
5b).

Further, each layer of the transfer drum 11 is, as shown in FIG. 9, a conductor layer 26> semiconductor layer 27> dielectric layer 2
8 is formed so that the semiconductive layer 27 forms a grounded aluminum base tube 15a of the photosensitive drum 15.
May come into contact with.

That is, the conductor layer 26 is formed by the power source section 32.
When a + voltage is applied to the conductive layer 26, a + charge is induced in the conductor layer 26, and the + charge moves to the surface of the semiconductive layer 27. At this time, if the grounded aluminum base tube 15a of the photoconductor drum 15 and the semiconductive layer 27 contact each other, all the charges charged in the semiconductive layer 27 are transferred to the aluminum base tube 15a, and the dielectric It becomes impossible to induce a positive charge on the surface of the body layer 28. Therefore, the transfer drum 11 cannot adsorb the negatively-charged toner adsorbed on the OPC film 15b, and a transfer failure occurs.

Therefore, each layer of the transfer drum 11 is as shown in FIG.
As shown in FIG. 7, the conductor layer 26 and the dielectric layer 28 have the same width, and the semi-conductor layer 27 has a width smaller than each of the widths described above, so that the semi-conductor layer 27 is grounded. It is possible to prevent contact with the aluminum base tube 15a and prevent leakage of charges. As a result, the transfer drum 11
Can adsorb negatively charged toner adsorbed on the OPC film 15b, and transfer defects can be eliminated.

Further, the diameter of the transfer drum 11 is formed so that one transfer sheet can be wound without overlapping, that is, the maximum width or length of the transfer sheet that can be used in the present image forming apparatus. Has been done. As a result, the transfer paper can be stably wound around the transfer drum 11, and as a result, the transfer efficiency is improved and the image quality can be improved.

Here, an image forming process in the image forming apparatus having the above-mentioned structure will be described with reference to FIGS. 2, 6 and 7.

First, as shown in FIG. 2, in the case of automatic paper feeding, the paper feed cassette 5 provided at the bottom of the main body transfers the transfer paper one by one from the top to the PF roller 8 by the pickup roller 7. The transfer paper sent to the PF roller 8 and passed through the PF roller 8 is transferred to the transfer drum 1 by the pre-curl roller 10.
Curl along the shape of 1.

On the other hand, in the case of manual paper feeding, the transfer paper is sent out one by one from the manual paper feeding unit 6 provided on the front surface of the main body.
It is conveyed to the pre-curl roller 10 by the manual feed roller 9. Then, the transfer paper is curled by the pre-curl roller 10 along the shape of the transfer drum 11.

Next, as shown in FIG. 6, the transfer paper P curled by the pre-curl roller 10 is transferred to the transfer drum 11
And the transfer roller 1 is conveyed between the transfer roller 1 and the ground roller 12.
The electric charge accumulated in the semiconductive layer 27 of the first
Electric charges are induced on the surface of the transfer paper P via the surface 7 and the inner surface of the transfer paper P. As a result, the transfer paper P is electrostatically attracted to the surface of the transfer drum 11.

After that, the transfer paper P attracted to the transfer drum 11 is conveyed to the transfer point X, which is the pressure contact portion between the transfer drum 11 and the photosensitive drum 15, as shown in FIG. The toner image is transferred onto the transfer paper P by the potential difference between the charge of the toner formed on the surface of the transfer paper P and the charge on the surface of the transfer paper P.

At this time, the photosensitive drum 15 is charged, exposed, developed and transferred for each color. Therefore, the transfer paper P remains attracted to the transfer drum 11,
It rotates on the transfer drum 11, and one color is transferred every one rotation, and one full-color image is obtained by a maximum of four rotations. However, when a monochrome image or a mono-color image is obtained, the transfer drum 11 may be rotated once.

Further, when all the toner images are transferred onto the transfer paper P, the transfer paper P is transferred to the transfer drum 11 by the peeling claws 14 provided on the circumference of the transfer drum 11 so as to be able to come into contact with and separate from the transfer drum 11.
It is forcibly separated from the surface and guided to the fixing guide 22.

After that, the toner image on the transfer paper P is guided by the fixing guide 22 to the fixing roller 23, and is fused and fixed on the transfer paper P by the temperature and pressure of the fixing roller 23. Then, the fixed transfer paper P is ejected from the discharge roller 24.
Is discharged onto the discharge tray 25.

As described above, the transfer drum 11 is formed from the inside by the conductive layer 26 made of aluminum, the semiconductive layer 27 made of urethane foam, and the dielectric layer 28 made of polyvinylidene fluoride.

As a result, by applying a voltage to the conductor layer 26, charges are sequentially induced from the conductor layer 26,
Electric charges are accumulated in the semiconductive layer 27. Then, when the transfer paper P is conveyed between the transfer drum 11 and the ground roller 12, the electric charge accumulated in the semiconductive layer 27 is moved to the transfer paper P, and the transfer paper P is transferred to the transfer drum 11. It is designed to be absorbed in advertising.

Therefore, the transfer paper P is not attracted and transferred by the charge injection by air discharge, but the transfer paper P is attracted and transferred by the induction of charges, so that the voltage can be low and the voltage can be controlled. Cheap. In addition, it is possible to eliminate variations in voltage due to external pressure.

Further, since the voltage applied to the transfer drum 11 can be kept constant without being affected by the environment such as humidity and temperature, the transfer efficiency can be improved and the image quality can be improved. .

Since the surface of the transfer drum 11 can be charged more stably than in the conventional case where electric charges are induced on the surface of the transfer drum 11 by discharge,
The transfer paper P can be attracted and transferred stably.

Moreover, by simply applying a voltage to the conductor layer 26, charges can be induced in the order of the semi-conductor layer 27 and the dielectric layer 28 to charge the surface of the transfer drum 11, so that transfer is performed by air discharge. As compared with the case where the surface of the drum 11 is charged, a lower voltage is required, so that voltage control becomes easier and less driving energy is required.

Further, since it is only necessary to apply a voltage to one place, it is not necessary to apply a voltage to each charger as in the conventional case, the device can be simplified and the manufacturing cost can be reduced. Can be Also, the transfer drum 1
Since the charging of No. 1 is performed by contact charging, the electric field region does not change even if the surface of the transfer drum 11 is flawed.
The electric field balance does not get out of order on the flawed portion of the surface of the transfer drum 11. As a result, transfer defects such as white spots do not occur at that portion, so that transfer efficiency can be improved.

Further, unlike air discharge, it is unlikely to be affected by the environment such as the temperature and humidity of the air, so that the surface potential of the transfer drum 11 does not fluctuate, and the improper adsorption of the transfer paper P and the print bleeding can be eliminated. it can. Also by this, the transfer efficiency can be improved and the image quality can be improved.

Although cylindrical aluminum is used as the conductor layer 26, other conductors may be used. Further, although the semiconductive layer 27 is formed of urethane foam, an elastic body such as silicon may be used as another semiconductive body, and the dielectric layer 28 is formed of polyvinylidene fluoride. However, a resin such as polyethylene terephthalate may be used as another dielectric.

After the discharge is completed, charge is injected in the nip between the transfer drum 11 and the ground roller 12 (see FIG. 10).
Area B) occurs, and a negative charge is further accumulated between the transfer drums. The structure in which charge injection occurs will be described with reference to the equivalent circuit (FIG. 11) shown below.

In FIG. 11, E is the applied voltage, r1 is the resistance of the semiconductive layer, r2 is the resistance of the dielectric layer, r3 is the resistance of the transfer paper, and r4 is the resistance of the minute gap between the ground roller and the transfer drum. C1 is the capacitance of the dielectric layer, C2 is the capacitance of the transfer paper, C3 is the capacitance of the minute gap between the ground roller and the transfer drum, and the charge injection is accumulated in the capacitor by the current flowing through the circuit. The amount of electric charge is calculated.

This time, in order to obtain the charge amount (potential) accumulated on the transfer paper C2, the above-mentioned equivalent circuit is solved for the potential difference (V2) applied to C2 with the charge amount (potential) charged by the passion discharge as the initial potential. The charging potential is calculated in consideration of both passion discharge and charge injection. The final charged potential V2 of the analytical expression of C2 obtained in this manner is, V2 = A × (b ' × e B -c' × e C) A, B, C, b ', c' is dependent on the circuit It becomes a constant.

In FIG. 2, although not shown in the figure, a paper type detection sensor is set in front of the suction roller of the conveyance path. For example, the paper type detection sensor is used to transmit the transmissivity of transfer paper. Is measured and the paper type of paper and OHP can be detected. Alternatively, the paper type detection sensor can detect the paper thickness and detect the paper type of thick paper or thin paper. That is, the nip time described later is adjusted according to the paper type (OHP, paper or thick paper, thin paper) detected here.

The nip time is determined by (nip width formed between the transfer drum 11 and the electrode member 12) / (transfer drum rotation speed). The nip width is semi-conductive layer 2
It can be adjusted by changing the hardness of 7.
The hardness of the semiconductive layer 27 is specified by Asker C,
Asker C is a regulation by the Japan Rubber Association, and is a unit system in which the shape of the push needle is sphere and the spring load is 55 g at 0 degree and 855 g at 100 degree. Table 1 shows the relationship between Asker C and the electrostatic attraction force of the transfer paper.

[0054]

[Table 1]

As a result, the hardness of the semiconductive layer 27 is 20.
If the hardness is less than the following, the transfer paper is curled in the opposite direction (not along the transfer drum 11), and if the hardness is 80 or more, the contact property with the photoconductor is deteriorated and the life of the photoconductor is shortened. For the above mechanical reasons, the hardness of the semiconductor layer 27 is preferably 20 or more and 80 or less, and more preferably 25 or more and 50 or less.

In addition, there is a method of adjusting the nip width by changing the contact pressure between the transfer drum 11 and the electrode member 12. The nip width formed between the transfer drum 11 and the electrode member 12 can be set by adjusting their contact pressures. As a method of adjusting the contact pressure, by rotating an eccentric cam below the electrode member 12, the contact pressure between the transfer drum 11 and the electrode member 12 is adjusted, and the nip width is arbitrarily set. There is. Table 2 shows the relationship between the nip width and the electrostatic attraction capacity of the transfer paper.

[0057]

[Table 2]

As a result, when the nip width is 0.5 mm or less, the electrode member 12 does not follow the transfer drum 11 and stable transfer paper cannot be conveyed. On the other hand, when the thickness is 6.0 mm or more, the nip width is 0.5 mm because the nip pressure is too strong and curling occurs in the opposite direction (not along the transfer drum 11).
5.0 mm or less is preferable and 1.0 mm is more preferable.
It is most preferably not less than 4.0 mm.

As described above, if the rotation speed of the transfer drum is constant, the nip time can be set by adjusting the nip width formed between the transfer drum 11 and the electrode member 12. Further, as a method of adjusting the nip time, a method of changing the rotation speed of the transfer drum can be considered.

Next, the mechanism of electrostatic attraction of the transfer paper will be described in detail. As described above, the charging of the dielectric layer using the conductive roller mainly consists of Paschen discharge and charge injection. First, the mechanism of performing Paschen discharge will be described.

In the mechanism for carrying out the Paschen discharge, as the distance between the ground roller 12 and the dielectric layer 28 on the transfer drum 11 becomes closer and the electric field strength applied to the minute gap becomes stronger, airborne dielectric breakdown occurs and discharge occurs. (Area A in FIG. 10).

Since a voltage of + (-) is applied between the transfer drum 11 (dielectric layer 28) and the ground roller 12, when discharge occurs,-(+) is applied to the transfer drum side (transfer paper).
Charges are accumulated.

Now, the rotation speed of the transfer drum is 85 mm / s.
ec, when the nip width formed between the transfer drum 11 and the electrode member 12 is 4 mm, the nip time is 0.047 seconds. Nip time 0.047 seconds charge amount (-1740
V) is smaller than the initial charge amount (-1800 V), which shows that the electrostatic adsorption capacity of the transfer paper is weakened. In this case, at least in order to set the charging potential after the charge injection is not lower than the initial charging potential, the nip width (for example, 3 mm) is reduced or the rotational speed of the transfer drum (for example, 95 mm / sec) is increased. There are possible ways to do it. Furthermore, in order to perform charge injection efficiently, an extreme value (nip time 0.01
It is conceivable to set the nip width to 0.85 mm or to set the rotation speed of the transfer drum 11 to 300 mm / sec so that the charge injection is performed in (second).

The charge injection when OHP is used for the transfer paper tends to increase with the passage of the nip time. That is, if the set nip time satisfies the mechanical nip conditions (Table 1 and Table 2), it is understood that the charge injection is always performed. If the transfer paper is paper, a semiconductive layer,
When the resistance value of the dielectric layer is increased, charge injection is not performed at all,
It can be seen that there is a tendency to decrease from the initial charging potential.

Table 3 shows the relationship between the electrostatic adsorption ability and the charge injection amount.

[0066]

[Table 3]

In such a case, the nip time is set so that the nip time satisfies the mechanical nip conditions (Tables 1 and 2) and is 50% or more of the initial charge injection amount. There is no fear of impairing the electrostatic adsorption ability of the transfer drum (for example, the nip width is set to 0.85 mm to set the nip time to 0.01 seconds, or the rotation speed of the transfer drum 11 is set to 300 mm / sec. It is possible).

As described above, the type of paper (for example, paper, OH
By changing the nip time according to the detection of P), charge can be efficiently injected and stable electrostatic attraction of the transfer paper can be performed. Moreover, the above theoretical values have been confirmed by experiments.

Table 4 shows a table of the charging potential difference before and after the charge injection.

[0070]

[Table 4]

Here, it is understood that the paper adsorption capability is weakened when a potential difference of about 1000 V or more is provided. The reason for this is that if the nip time is increased (the nip width is increased) in order to increase the charge application amount, the transfer drum 11 and the electrode member 1
It is considered that there is a mechanical reason such that the nip pressure between the sheet and the sheet 2 becomes large and reverse curl occurs on the transfer sheet. Further, the nip time can be increased by slowing the process speed while keeping the nip width as it is, but it is considered that the printing efficiency per minute is deteriorated because the process speed for applying a potential of 1000 V or more is too slow. Therefore,
It can be considered that the most suitable potential difference before and after the charge injection is 0 V or more and 1000 V or less.

In the above-described image forming apparatus, a light irradiating means for irradiating the image carrier with light is provided upstream of the transfer process of the toner image formed on the image carrier and after the developing process. Will be described with reference to FIGS. 12 and 13.

In the image forming apparatus of Embodiment 1, when an intermediate transfer member is used, it is used by adhering the above-mentioned high dielectric material such as polyvinylidene fluoride, silicon or polyethylene terephthalate to a support made of aluminum. can do.

FIG. 12 is a schematic structural diagram of a color copying machine (laser beam printer) which is an image forming apparatus.
Is a transfer member, 52 is a color developing unit, 53 is an image carrier, 54 is a black developing unit, 55 is a pre-curl roller,
56 is a suction roller, 57 is a cleaning member for cleaning the transfer body 51, 58 is a charge removing mechanism (charge removing brush) for the transfer body 51, and 59 is a peeling claw for peeling the transfer paper from the transfer body 51. The transfer body 51 is composed of a dielectric layer 51a, an elastic resistance layer 51b, and a conductive layer 51c.

Reference numeral 60 denotes an LED element having a wavelength band of about 600 to 780 mm, which has a red wavelength band outside the light absorption band of the carrier moving layer of the image carrier 53 as a light irradiating means. It is installed between the image carrier 53 and the transfer body 51. The LED element 60 is installed with an element pitch of 5 mm and a distance of about 15 mm from the image carrier 53, and an input voltage of 2.2 V to 5.0 V is applied.

Then, before the toner transfer process from the image carrier 53 to the transfer paper and after the developing process, the LED device 60 emits light in a wavelength range that can substantially pass through the carrier moving layer to the image carrier 53.
By irradiating the carrier transfer layer, the light irradiated to the carrier transfer layer is surely transmitted, and since this light reaches the carrier generation layer, deterioration of the carrier transfer layer can be suppressed and the background potential can be reliably removed. It is possible to reliably prevent the transfer electric field from decreasing.

Therefore, when carrying out continuous multiple transfer, for example, when a color image is formed, the image carrier (photoreceptor) is changed over time.
Fatigue can be prevented, and stable multiple transfer can be performed.

Embodiment 2 of the image forming apparatus of the present invention is shown in FIG.
4 will be described. In the second embodiment, the LE is provided on the transfer body side of the developing unit 62 having the developing sleeve 61 in which the developing Gap is formed and arranged under the image carrier 53.
The substrate 63 for the D element is provided, the LED element 60 is provided on the substrate 63 for the LED element, and the light emitted from the LED element 60 on the developing position side of the image carrier 53 and the developing sleeve 61 of the LED element 60. A light blocking member 64 for blocking the light is provided.

With the above structure, the image carrier and the fixed transfer drum or the intermediate transfer medium are used, such as a fixed transfer drum which adsorbs the transfer paper and directly transfers from the image carrier, or a small image forming apparatus using an intermediate transfer member. Even if there is no installation space between the transfer body and the transfer member, the LED element 60 is
It prevents the light from from irradiating the developing position and disturbs the toner image at the time of development.

Further, even when an omnidirectional LED is used, it is possible to prevent the light emitted from the LED element 60 from being shielded by the light shielding member 64 and prevent the toner image from being disturbed.

Here, the LED element 60 is used, but the short wavelength component is cut off by an optical filter.
The same effect can be obtained by using a fluorescent lamp that irradiates a wavelength range of 00 nm or more.

Further, instead of the light shielding member 64, the traveling optical path of the light emitted from the LED element 60 may be regulated. Then, in Embodiments 1 and 2 described above, when a directional LED (a LED of ROHM F336 LED with a concave lens) is used, the distance to the image carrier surface without leakage of light to the surroundings can be obtained. When it is set to about 15 mm, the irradiation light is concentrated on a region of about 5 to 7 mm on the image carrier when the area of the light emitting portion protection surface is about 3 mm × 3 mm. Therefore, due to the concentration of the irradiation light, it is possible to prevent the light from entering the near developing portion and prevent the toner image from being disturbed. Further, even if the above-mentioned directional LED is installed at a distance of about 13 to 17 mm from the developing section, there is no adverse effect due to the entry of light into the developing section.

FIG. 1 shows Embodiment 3 of the image forming apparatus of the invention.
It will be described together with 5. In the third embodiment, by arranging the light emitting surface of the LED element 60 closer to the image carrier 53 than the extension line of the tangent line from the developing position of the image carrier 53 and the developing sleeve 61, the LED element 60 emits light. The light from the surface is prevented from entering the developing position.

Therefore, the desired performance (the background potential can be reliably provided) can be obtained by merely setting the emitted light amount of the LED element 60 to the light amount for removing the background potential of the image carrier 53. Further, the potential removal effect does not deteriorate due to the inclination of the light emitting surface of the LED element 60. In this case, a similar potential removing effect can be obtained even with a fluorescent lamp using an optical filter.

[0085]

According to the image forming apparatus of the present invention , the laminated type
Light in the wavelength range that can be transmitted through the carrier transfer layer of the image carrier
By morphism irradiation, by reaching the light irradiated to career generating layer, by suppressing the deterioration of the carrier transport layer can be reliably discharges the background potential, it can be reliably prevented a drop in transfer charge. Moreover, since it is possible to prevent the image carrier from fatigue over time, for example, when performing color image formation in which continuous multiple transfer is performed continuously, stable multiple transfer can be performed.

[0086]

[0087]

Further, the light emitting surface of the light emitting element of the light irradiation means.
The light from the light emitting surface advances to the developing position of the image carrier.
In order to prevent the image carrier from entering, the image carrier is closer to the image carrier than the extension of the tangent line from the developing position of the image carrier, and
Because it is arranged to illuminate a only light from the light emitting surface can prevent from entering into the developing position, to the amount of light the emitted light amount of the light-emitting element can be removed the background potential of the image carrier The desired performance (the background potential can be surely removed) can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a basic structure of an image forming apparatus of the present invention.

FIG. 2 is a schematic sectional view of a copying machine including the image forming apparatus shown in FIG.

3 is a schematic cross-sectional view showing a configuration of a transfer drum of the image forming apparatus shown in FIG.

FIG. 4 is a conductor layer that forms the transfer drum shown in FIG. 3;
It is explanatory drawing which shows the connection state with a semiconductive layer and a dielectric layer.

FIG. 5 is a conductor layer that forms the transfer drum shown in FIG.
It is another explanatory view showing a connection state with a semiconductive layer and a dielectric layer.

FIG. 6 is an explanatory diagram showing a charged state of the transfer drum shown in FIG. 3, and is an explanatory diagram showing an initial state in which a transfer sheet is conveyed to the transfer drum.

FIG. 7 is an explanatory diagram showing a charged state of the transfer drum shown in FIG. 3, and is an explanatory diagram showing a state in which a transfer sheet is conveyed to a transfer position of the transfer drum.

FIG. 8 is an explanatory diagram showing a comparison between a charging width of the transfer drum shown in FIG. 3 and an effective image width.

9 is an explanatory view showing charge transfer between the transfer drum and the photosensitive drum shown in FIG. 3, and showing charge transfer when the width of each layer of the transfer drum is such that dielectric layer <semiconductor layer <conductor layer. Is.

FIG. 10 is an explanatory diagram illustrating the operation of Paschen discharge in the image forming apparatus of the present invention.

FIG. 11 is an equivalent circuit diagram illustrating charge injection between the transfer drum and the ground roller of the image forming apparatus of the present invention.

FIG. 12 is a schematic sectional view showing Embodiment 1 of the image forming apparatus of the invention.

13 is a cross-sectional view showing the transfer body of FIG.

FIG. 14 is a schematic sectional view showing Embodiment 2 of the image forming apparatus of the invention.

FIG. 15 is a schematic sectional view showing Embodiment 3 of the image forming apparatus of the invention.

[Explanation of symbols]

51 transfer body 52 color development unit 53 Image carrier 54 Black Development Unit 55 Pre-curl roller 56 Adsorption roller 57 Cleaning member 58 Static elimination mechanism 59 Peeling nail 60 LED elements

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-8-339126 (JP, A) JP-A-8-95448 (JP, A) JP-A1-273077 (JP, A) JP-A-7- 56447 (JP, A) JP 5-165383 (JP, A) JP 9-16054 (JP, A) JP 7-175338 (JP, A) JP 8-110671 (JP, A) JP 55-67778 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/00 303 G03G 21/00 370-540 G03G 15/16-15/16 103 G03G 21 / 00 345 G03G 21/06-21/08

Claims (2)

(57) [Claims] 1. A stack type image carrier on which a toner image is formed, and a transfer paper are electrically attracted and held, and the transfer paper is brought into contact with the image carrier to form an image on the image carrier. And a transfer unit that rotates at a predetermined rotation speed to transfer the toner image formed on the transfer layer, the transfer unit including a dielectric layer, a semiconductive layer, and a conductive layer from the contact surface side of the transfer paper. Are laminated in order, and a grounded electrode member is in contact with the surface on the upstream side from the transfer position on the surface of the dielectric layer via a transfer paper; a voltage applying means for applying a predetermined voltage to the conductor layer; and charge removing means for neutralizing the body layer, wherein an image forming apparatus having a cleaning means, a to remove residual toner on the dielectric layer, upstream of the transfer step of the toner image formed on the image bearing member and developing After the process, the carrier of the image carrier is transferred to the image carrier. The light emitting means for emitting light in the wavelength range not absorbed by the moving layer is provided, and the light emitting surface of the light emitting element of the light emitting means is
It is necessary to prevent light from entering the developing position of the image carrier.
In addition, it is arranged on the image carrier side of the extension line of the tangent line from the developing position of the image carrier and irradiating the image carrier.
An image forming apparatus characterized by being installed . 2. A laminate type image carrier on which a toner image is formed, and at least a resistor or a dielectric, which are formed on the image carrier by bringing them into contact with the image carrier. An intermediate transfer unit that rotates at a predetermined rotation speed for transferring a toner image, wherein the intermediate transfer unit has a charging unit that charges the surface of the dielectric layer; An image forming apparatus, comprising: a cleaning unit that removes residual toner on the dielectric layer; and an image carrier on the image carrier, upstream of the transfer process of the toner image formed on the image carrier and after the developing process. A light emitting means comprising a light emitting element for emitting light in a wavelength range not absorbed by the carrier moving layer of the body is provided, and the light emitting surface of the light emitting element of the light emitting means is
It is necessary to prevent light from entering the developing position of the image carrier.
In addition, it is arranged on the image carrier side of the extension line of the tangent line from the developing position of the image carrier and irradiating the image carrier.
An image forming apparatus characterized by being installed .