JP5413658B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to various image forming apparatuses such as a copying machine, a facsimile machine, a printer, and a composite machine of these, which use constant current control as control when transferring a toner image onto a transfer material.

  When constant current control is used for control when transferring a toner image to a transfer material, there arises a problem that transferability varies depending on the size of the transfer material. For example, when a transfer material (paper) whose width is narrower than the width of the intermediate transfer member or transfer member (transfer belt) is used, the transfer current selectively flows through the non-sheet passing portion. This is because the transfer material has a higher resistance value, and the transfer current flows more easily in the non-sheet passing portion having a relatively low resistance value. For this reason, for example, in a printer capable of passing A3 size paper, when A4 size paper is fed vertically or B4, A5, or B5 size paper, most of the transferred current flows to the non-sheet passing portion, which causes transfer failure. May occur.

  In addition, when the resistance value of the intermediate transfer member or the transfer member is low, for example, when an intermediate transfer member or transfer member having a low resistance value is used due to manufacturing variations, or the difference in resistance value between the intermediate transfer member or the transfer member and the paper is Under conditions that increase, for example, the resistance value of the intermediate transfer member or transfer member decreases, and the resistance value of the paper as the transfer material increases. As a result, the transfer defect is more likely to occur.

  Furthermore, even during double-sided printing, where the paper is dried after passing through the fixing device, this phenomenon is most noticeable because it dries out and the paper is dehydrated and has the highest resistance. And the color and image quality on the first and second sides may be completely different.

  In Patent Document 1, transferability is ensured by switching between constant voltage control and constant current control according to the paper size as a transfer material. However, since it is necessary to have a power supply for constant voltage control and a power supply for constant current, the cost of the apparatus increases.

  In Patent Document 2, a toner layer is printed on a non-sheet passing portion. The toner in the non-sheet passing portion serves as a resistance member in the transfer nip portion, the current flowing directly to the photoreceptor 1 is suppressed, and a charge necessary for transferring the toner image is secured. Therefore, the image quality is not deteriorated due to the size of the transfer paper, but the cost increases because a large amount of toner is used. Further, there is a possibility that the secondary transfer member is soiled with toner, or that the back surface of the transfer material is contaminated in the printing procedure of the next process.

  SUMMARY OF THE INVENTION In view of the above-described conventional problems, an object of the present invention is to provide an image forming apparatus using constant current control capable of ensuring transferability of small size paper through a simple mechanism at low cost. .

The image forming apparatus according to the first aspect of the present invention is an image forming apparatus using constant current control as a control when a toner image developed on an image carrier or an intermediate transfer member is transferred to a transfer material by a transfer unit. In the device
The portion corresponding to a portion other than the main scanning width when the toner image is formed on the transfer material to which the toner image is transferred, and the transfer means and the image carrier or intermediate transfer member are in direct contact with each other. A resistance member sandwiching means for sandwiching the resistance member with respect to at least a part of the portion;
The resistance member pinching means is one while transferring at least the toner image on the transfer material sandwiching said resistor member,
The resistance member is an OHP sheet ;
It is characterized by that.

According to a second aspect of the present invention, there is provided an image forming apparatus using constant current control as a control when a toner image developed on an image carrier or an intermediate transfer member is transferred to a transfer material by a transfer unit.
The portion corresponding to a portion other than the main scanning width when the toner image is formed on the transfer material to which the toner image is transferred, and the transfer means and the image carrier or intermediate transfer member are in direct contact with each other. A resistance member sandwiching means for sandwiching the resistance member with respect to at least a part of the portion;
The resistance member sandwiching means sandwiches the resistance member at least during the transfer of the toner image to the transfer material.
A plurality of process cartridges including a developing device for developing the image carrier and the toner image;
When printing a color image, the developing device forms a toner image on the image carrier with the developing device of each of the process cartridges. When printing a monochromatic image, the developing device of any one of the process cartridges in have line the process,
The resistance member is an OHP sheet ;
It is characterized by that.

According to a third aspect of the present invention, there is provided an image forming apparatus that uses constant current control as control when a toner image developed on an image carrier or an intermediate transfer member is transferred to a transfer material by a transfer unit.
The portion corresponding to a portion other than the main scanning width when the toner image is formed on the transfer material to which the toner image is transferred, and the transfer means and the image carrier or intermediate transfer member are in direct contact with each other. A resistance member sandwiching means for sandwiching the resistance member with respect to at least a part of the portion;
The resistance member sandwiching means, while transferred to the transfer material at least the toner image seen come sandwiching said resistor member,
A plurality of process cartridges including a developing device for developing the image carrier and the toner image;
When printing a color image, the developing device forms a toner image on the image carrier with the developing device of each of the process cartridges. When printing a monochromatic image, the developing device of any one of the process cartridges To perform the above steps,
A toner image formed on the image carrier by the developing device is then transferred from the image carrier to an intermediate transfer member composed of an endless belt stretched around a plurality of rollers, thereby forming a color image. Holding, primary transfer means for transferring the toner images for each process cartridge so as to overlap each other;
Secondary transfer means for transferring the toner image on the intermediate transfer member to a transfer material;
The resistance member is an OHP sheet ;
It is characterized by that.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the thickness of the resistance member is smaller than the thickness of the transfer material .

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the resistance of the resistance member is higher than that of the transfer material .

According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the resistance member has a surface resistance of 9 logΩ / □ or more and 14 logΩ / □ or less, and a volume resistance of 9 logΩ · cm or more and 14 logΩ · cm or less. and characterized in that it is of.

According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the image forming apparatus further comprises a detecting unit for detecting the width and thickness of the transfer material.

According to an eighth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to seventh aspects, further comprising a resistance member moving unit that moves the resistance member, and the resistance member moving unit moves the resistance member to a main scanning width. the amount of sliding direction, the same camphor characterized Rukoto a moving amount of the transfer material feeding to provided in the tray transfer material width regulating guides.

According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, an interlocking unit that links the movement of the resistance member by the resistance member moving unit with the movement of the transfer material width regulation guide is provided. It is characterized by that.

A tenth aspect of the present invention is the image forming apparatus according to any one of the first to ninth aspects, further comprising paper type setting means for setting a paper type of the transfer material , wherein the width dimension of the transfer material is set to the paper type setting means. in a detectable from the set sheet type, the resistive member movable means, characterized in der Rukoto shall establish the resistance member to a non-paper passing area in the motor drive.

According to an eleventh aspect of the present invention, in the image forming apparatus according to any one of the first to tenth aspects, a sensor for detecting temperature and humidity is provided, and the resistance member sandwiching means is a detected value of temperature and / or humidity by the sensor. Only when a predetermined threshold value exceeds a predetermined threshold, the secondary transfer means and the secondary transfer means are located outside the transfer material region at a portion corresponding to the transfer width in the transfer material width direction of the image carrier according to the size of the transfer material. The resistance member is sandwiched between the intermediate transfer materials .

  According to the present invention, it is possible to provide an image forming apparatus capable of ensuring transferability of small-size paper through a low-cost and simple mechanism.

Sectional drawing which shows the outline of an example of the image forming apparatus which can be the implementation object of this invention A perspective view conceptually showing the structure in the vicinity of the driving and secondary transfer counter roller and the secondary transfer roller A perspective view conceptually showing the structure in the vicinity of the driving and secondary transfer counter roller and the secondary transfer roller , Diagram showing the transfer efficiency when the thickness level of the resistance member is changed when printing a solid image on a small size transfer material Diagram showing transfer efficiency when the surface resistance and volume resistance of the resistance member are varied when printing a solid image on a small transfer material The figure shown about the structure which detects the thickness and width | variety of the transfer material 22 View from the top of the paper cassette Conceptual diagram showing a configuration in which a resistance member is automatically sandwiched between non-sheet passing portions by setting a paper feed tray to the main body of the image forming apparatus. The perspective view which shows the operation state of the example shown in FIG. Conceptual diagram showing a configuration in which the resistance member is attached to the support portion while being inclined. FIG. 5 is a diagram illustrating an image forming apparatus according to a second embodiment of the invention. The figure which similarly shows Example 2 The figure which similarly shows Example 3

  As an embodiment of the image forming apparatus of the present invention, in an image forming apparatus using constant current control as a control when transferring a toner image developed on an image carrier or an intermediate transfer member onto a transfer material by a transfer unit, The portion corresponding to a portion other than the main scanning width when the toner image is formed on the transfer material to which the toner image is transferred, and the transfer means and the image carrier or intermediate transfer member are in direct contact with each other. A resistance member sandwiching means for sandwiching the resistance member is provided for at least a part of the portion, and the resistance member sandwiching means sandwiches the resistance member at least during the transfer of the toner image to the transfer material. Further, as an embodiment, a plurality of process cartridges including a developing device that develops the image carrier and the toner image are provided, and when the color image is printed, the developing device places the process cartridge on the image carrier. A toner image forming step is performed by the developing device of each of the process cartridges, and at the time of printing a single color image, the above-described step can be performed by the developing device of any one of the process cartridges. Occasionally, charge is prevented from leaking to the non-sheet passing portion of the transfer material, thereby ensuring transferability.

  In the present invention, a sheet-shaped object is adopted as the resistance member, so that it is inexpensive and does not affect the transfer material transfer. An OHP sheet can be adopted as the resistance member. This is cheap. Further, since the resistance member is thinner than the transfer material, that is, the thickness is smaller than that of the transfer material, it is possible to ensure transferability without forming a gap between the secondary transfer member and the intermediate transfer member.

  The resistance of the resistance member is preferably higher than that of the transfer material. This is to prevent charges from leaking to the non-sheet passing portion of the transfer paper during the secondary transfer. Such a resistance member preferably has a surface resistance of 9 logΩ / □ or more and 14 logΩ / □ or less and a volume resistance of 9 logΩ · cm or more and 14 logΩ · cm or less. It is possible to prevent electric charge from leaking to the non-sheet passing portion of the transfer paper during the secondary transfer.

  It is preferable to provide means for detecting the width and thickness of the transfer material. This is because transferability can be ensured by not forming a gap between the secondary transfer member and the intermediate transfer member.

  Further, the sliding amount of the resistance member in the main scanning width direction is preferably the same as the moving amount of the transfer material width regulation guide provided in the tray for feeding the transfer material. This is to prevent charges from leaking to the non-sheet passing portion of the transfer paper during the secondary transfer.

Furthermore, when the movement of the resistance member is interlocked with the movement of the transfer material width restriction guide provided in the tray when the user feeds the transfer material,
The user may be able to install the resistance member in the non-sheet passing area simply by setting the transfer paper. In addition, paper type setting means for setting the paper type of the transfer material is provided so that the width dimension of the transfer material can be detected from the paper type setting, and the resistance member moving means is driven by a motor so that the resistance member is not passed. It should be installed in the area. This is because transferability can be ensured by not forming a gap between the secondary transfer member and the intermediate transfer member.

  Furthermore, the temperature and humidity are detected by a sensor, for example, an environmental sensor, and only when a predetermined threshold value is exceeded, transfer of a portion corresponding to the transfer width in the transfer material width direction of the image carrier is performed according to the size of the transfer material. It is preferable to sandwich a resistance member between the secondary transfer means and the intermediate transfer material outside the material region. By detecting whether the resistance member is installed by detecting the environment, it is possible to ensure better transferability.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the illustrated color image forming apparatus, and can be applied to various image forming apparatuses such as an apparatus for forming a monochrome image. In the following description, a description such as “m ^ 3” indicates a power or a power such as “m to the third power”.

  FIG. 1 is a cross-sectional view schematically showing an example of an image forming apparatus that can be an object of the present invention. In the figure, reference numeral 1 denotes a cylindrical photosensitive drum having a diameter of 24 mm (an example of an image bearing member, hereinafter simply referred to as a photosensitive member), which rotates at a peripheral speed of 120 mm / s, for example. A roller-shaped charger 2 serving as charging means is pressed against the surface of the photosensitive member 1, and is driven to rotate by the rotation of the photosensitive member 1, and a bias in which AC is superimposed on DC or DC by a high voltage power source (not shown). Is applied, the photoreceptor 1 is uniformly charged to a surface potential of −500V.

  After the photoreceptor 1 is charged, image information is exposed by an exposure unit 3 which is a latent image forming unit, and an electrostatic latent image is formed. In this exposure step, laser light that has been subjected to light modulation from a laser diode (LD) element 3 a forms an image on the surface of the photoreceptor 1. By scanning this laser beam, a latent image is written on the surface of the photoconductor 1 corresponding to a desired image, and an electrostatic latent image is formed on the photoconductor 1.

  In the figure, reference numeral 4 denotes a one-component contact developing device (hereinafter simply referred to as a developing device) which is a developing means, and an electrostatic latent image on the photoreceptor 1 is generated by a predetermined developing bias supplied from a high voltage power source (not shown). It is visualized as a toner image.

  In the figure, reference numeral 10 denotes a process cartridge in which the photosensitive member 1, the charger 2, and the developing unit 4 are integrated. The four process cartridges 10 are arranged in parallel and store yellow, magenta, cyan, and black toners. When a full color image is formed, a visible image is formed in the order of yellow, magenta, cyan, and black. The visible images of the respective colors are sequentially transferred to the same position while being superimposed on the abutting intermediate transfer belt 15 to form a full-color image.

  The intermediate transfer belt 15 includes a driving / secondary transfer counter roller 21 (to be described later: hereinafter simply referred to as the driving roller 21), a metal cleaning counter roller 16, a primary transfer roller 5 (to be described later), a tension roller. 20 (described later), and is rotated by a drive motor (not shown) via a drive roller 21. The belt tension is applied by springs on both sides of the tension roller 20. The tension roller 20 is, for example, an aluminum pipe shape having a diameter of 19 mm and a width of 231 mm. A flange having a diameter of 22 mm, for example, is press-fitted at both ends, and the meandering of the intermediate transfer belt 15 is restricted. The conveyance direction of the intermediate transfer belt 15 is the direction of the arrow shown in FIG.

  The drive roller 21 can be made of polyurethane rubber (thickness 0.3 to 1 mm), thin layer coating roller (thickness 0.03 to 0.1 mm), etc. It is preferred to use a small urethane coating roller. As the primary transfer member, a conductive blade, a conductive sponge roller, a metal roller, or the like can be used. In this embodiment, for example, a φ8 mm metal roller is used, and as shown in FIG. (For example, it can be assumed that the intermediate transfer belt 15 is offset by 8 mm in the moving direction of the intermediate transfer belt 15 and 1 mm in the vertical upward direction with respect to the photosensitive member 1). Then, a predetermined transfer bias is commonly applied to the primary transfer roller 5 from the single transfer roller 5 by a single high-voltage power source (not shown) to form a transfer electric field via the intermediate transfer belt 15. The toner image is transferred to the intermediate transfer belt 15.

  In the figure, reference numeral 17 denotes a toner mark sensor (TM sensor), which measures the toner image density and each color position on the intermediate transfer belt 15 by a regular reflection type or diffusion type sensor, and adjusts the image density and color matching.

  In the figure, reference numeral 32 denotes an intermediate transfer belt cleaning unit, which performs cleaning by scraping off transfer residual toner on the intermediate transfer belt 15 with a cleaning blade 31. As a material of the cleaning blade 31, urethane rubber having a thickness of 1.5 to 3 mm and a rubber hardness of 65 to 80 ° is used, and is in contact with the intermediate transfer belt 15 by a counter. The transfer residual toner thus scraped off is stored in the intermediate transfer member waste toner storage section 33 through a toner conveyance path (not shown). At least one of the portion corresponding to the cleaning nip portion of the intermediate transfer belt 15 or the edge portion of the cleaning blade 31 is coated with a coating agent such as a lubricant, toner, zinc stearate at the time of assembly. In addition to preventing the blade from rolling up, a dam layer is formed in the cleaning nip to enhance the cleaning performance. Each roller that stretches the intermediate transfer belt 15 is supported from both sides of the intermediate transfer belt 15 by an intermediate transfer belt unit side plate (not shown).

  Materials used for the intermediate transfer belt 15 include PVDF (vinylidene fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PC (polycarbonate), TPE (thermoplastic elastomer), and carbon. A conductive film such as black can be dispersed to form a resin film-like endless belt. In this embodiment, description will be made assuming that a belt having a surface resistance of 8 to 9 logΩ, a volume resistance of 8 to 9 logΩ, a tensile elastic modulus of 1000 to 2500 MPa, a thickness of 90 to 160 μm, and a width of 230 mm is used.

  In the figure, reference numeral 25 denotes a secondary transfer roller. The secondary transfer roller 25 covers, for example, an elastic body such as urethane adjusted to a resistance value of, for example, 10 ^ 6 to 10 ^ 10Ω with a conductive material on a metal core metal such as SUS having a diameter of 6 mm, for example. It is configured to have a diameter of 19 mm and a width of 222 mm. As the material, an ion conductive roller (urethane + carbon dispersion, NBR, hydrin) or an electronic conductive type roller (EPDM) can be used. In this embodiment, a urethane roller having a diameter of 20 mm and an Asker C hardness of 35 to 50 °. It is assumed that

  Here, if the resistance value of the secondary transfer roller 25 exceeds the above range, it becomes difficult for the current to flow. Therefore, in order to obtain a required transfer property, a higher voltage must be applied, which increases the power supply cost. Invite. In addition, since it is necessary to apply a high voltage, discharge occurs in the gap before and after the nip of the transfer portion, and white spots are lost on the halftone image due to the discharge. This is remarkable in a low-temperature and low-humidity environment (for example, 10 ° C. and 15% RH). On the other hand, if the resistance value of the secondary transfer roller 25 falls below the above range, transferability between a multicolor image portion (for example, a three-color superimposed image) and a single color image portion existing on the same image cannot be achieved. This is because the resistance value of the secondary transfer roller 25 is low, so that a sufficient current flows to transfer the monochrome image portion at a relatively low voltage. However, it is optimal for the monochrome image portion to transfer the multiple color image portion. This is because a voltage value higher than the voltage is required, and setting a voltage that can transfer a plurality of color image portions causes an excessive transfer current in a single color image, resulting in a decrease in transfer efficiency.

  The transfer material 22 is fed by a paper feeding / conveying roller 23 and a pair of registration rollers (described later) in accordance with the timing at which the front end of the toner image on the surface of the intermediate transfer belt 15 reaches the secondary transfer position. The toner image on the intermediate transfer belt 15 is transferred to the transfer material 22 by applying a predetermined transfer bias. In this configuration, the paper feed takes a vertical path. The transfer material 22 is separated from the intermediate transfer belt 15 by the curvature of the driving roller 21 that is a secondary transfer counter roller, and the toner image transferred to the transfer material 22 is fixed by the fixing means 40 and then discharged.

  FIG. 2 is an enlarged perspective view showing the periphery of the secondary transfer portion including the secondary transfer roller 25 described above, and the transfer material 22 passes between the intermediate transfer belt 15 and the secondary transfer roller 25. The state where the toner on the intermediate transfer belt 15 is secondarily transferred to the transfer material 22 is shown.

  In the present invention, as shown in FIG. 3, the resistance member 201 is sandwiched between the non-sheet passing portions to prevent the secondary transfer current from flowing into the non-sheet passing portions. The resistance member is preferably a thin sheet material such as an OHP sheet.

  FIG. 4 shows the transfer efficiency when the thickness level of the resistance member 201 is changed when printing a solid image on a small-size transfer material. It can be seen that the transfer efficiency is significantly reduced when the thickness of the resistance member 201 exceeds 120 μm, which is the thickness of the transfer material. Therefore, transferability cannot be ensured unless the resistance member is thinner than the transfer member.

  FIG. 5 shows the transfer efficiency when the surface resistance and volume resistance of the resistance member 201 are varied when printing a solid image on a small-size transfer material. In this example, the load of the secondary transfer system including the transfer material of a small size is 100 MΩ, and when the secondary transfer load of the non-sheet passing portion is 100 MΩ or less, the transfer efficiency is remarkably deteriorated. The transfer property can be secured when the resistance of the transfer material is larger than the resistance of the transfer material.

  FIG. 6 shows a configuration for detecting the thickness and width of the transfer material 22. The width direction dimension of the transfer material 22 is detected as follows. First, a weak current is passed from the power source 24a through the ammeter 24b to the secondary transfer roller 25 that forms a pair of registration rollers together with the driving roller 21, and the registration rollers are sandwiched between the pair of registration rollers. The width of the transfer material 22 is detected by reading the voltage applied to the pair with a voltmeter (not shown). The thickness dimension of the transfer material 22 is detected as follows. That is, immediately after the transfer material 22 passes between the pair of registration rollers (for example, a position within a moving distance of less than 10 mm after the transfer), the laser beam 703 is irradiated from the lateral direction of the transfer material 22 by the LD 701 and received on the opposite side. By providing the portion 702, the thickness of the transfer material 22 is detected from the difference between the region through which the laser beam 703 has passed and the region through which the laser beam 703 has not passed.

  FIG. 7 is a top view of the sheet cassette. A transfer material end regulating fence 801 for aligning both ends of the transfer material 22 is provided in the paper feed tray 800 and adjusted by moving the transfer material end regulating fence 801 in the direction of the arrow 802 according to the size of the transfer material 22. It can be done.

  FIG. 8 shows a configuration in which the resistance member is automatically sandwiched between the non-sheet passing portions by setting the sheet feeding tray in the apparatus main body of the image forming apparatus. When the transfer material end regulating fence 801 is set to the width of the transfer material and the paper feed tray is set on the apparatus main body of the image forming apparatus, the transfer material end regulating fence 801 is provided on the apparatus main body side. When the sheet feeding tray is completely set in the apparatus main body, the rotation support member 803 rotates by a predetermined angle and is attached to the tip of the support portion 804 that contacts the rotation support member 803. The resistance member 201 moves by a predetermined amount and can move to the non-sheet passing area. Therefore, when the user sets the transfer material 22 in the paper feed tray and further inserts the paper feed tray into the apparatus main body, the resistance member 201 is automatically sandwiched in the non-sheet passing area.

  Note that the resistance member 201 slides downward in the drawing in the support portion 804, the resistance member 201 contacts the secondary transfer roller 25, and loses its place in the sliding direction. As illustrated, the resistance member 201 is bent inward in the width direction of the secondary transfer roller 25. In this case, a guide 805 is provided to guide the resistance member 201 so that the resistance member 201 does not bend outside the secondary transfer roller 25. FIG. 9 is a perspective view showing an operation state of the example shown in FIG. Although the description will be omitted because it is redundant, (A) shows a state before the paper feed tray is set in the main body of the image forming apparatus, and (B) shows that the paper feed tray is set in the main body of the image forming apparatus. Shows the state.

  Further, as shown in FIG. 10, the resistance member 201 is not perpendicular to the support portion 804 but is attached to the transfer material end regulating fence 801 at an angle θ with respect to the vertical direction. 805 can be made unnecessary. However, in the example of FIG. 10, the guide 805 is provided similarly to the example of FIG.

  11 and 12 are diagrams showing an embodiment in which a paper feeding device is used as a manual feed tray in the image forming apparatus of the present invention. In this embodiment, when the transfer material is set on the manual feed tray 900, the transfer material end regulating fence 801 is moved in the direction of the arrow 901 in order to align the width direction of the transfer material as described above. The transfer material end regulating fence 801 includes a movable support portion 902 at its tip. As shown in FIG. 12, the movable support portion 902 has a saw-like notch at the center, and is in contact with the gear 903 having the same notch shape. Further, by attaching the second movable support portion 904 so as to intersect the movable support portion 902 vertically, when the movable support portion 902 is moved in the arrow 901 direction, the movable support portion 904 moves in the arrow 905 direction. By providing the trapezoidal resistance member 201 at the tip of the movable support portion 904, when the movable support portion 902 is moved by the width of the transfer material, the movable support portion 904 moves by a predetermined amount, and the resistance member 201 is subjected to secondary transfer. The member and the intermediate transfer belt 15 are sandwiched in the nip of the registration roller pair. Therefore, when the user performs an operation of setting the transfer material on the manual feed tray, the resistance member 201 is automatically sandwiched between the non-sheet passing regions.

  Note that when the user can set the type and size of the transfer material from the operation panel provided on the main body of the image forming apparatus or on the printer driver, the above-described size setting is automatically performed as described above. Thus, the resistance member can be sandwiched in the nip between the secondary transfer member and the intermediate transfer belt by driving the motor. For the setting on the printer driver, a known setting method may be used, and illustration and description thereof are omitted. However, as an apparatus configuration, for example, as shown in FIG. Control can be performed so that the above-described operation is performed. As a configuration for moving the resistance member 201, a configuration other than the example shown in the drawing may of course be employed.

  Also, a temperature / humidity sensor is provided on the side plate of the main body of the image forming apparatus. When the sensor reading is below 1.2 g / m ^ 3, for example, it exceeds 20.5 g / m ^ 3. Sometimes, the resistance member 201 can be moved. In the former, since the absolute moisture content is small, the resistance of the transfer material increases, and the secondary transfer load in the non-transfer material region becomes extremely small relative to the secondary transfer load in the transfer material region, and the secondary transfer current is not transferred. Leakage occurred in the material area and transfer failure occurred. In the latter condition, since the absolute water content is large, the secondary transfer load in the non-transfer material region is extremely small, and the secondary transfer current leaks to the non-transfer material region, resulting in transfer failure. Transferability can be ensured by inserting the resistance member into the nip portion of the secondary transfer portion only when the value is lower than 1.2 g / m ^ 3 or higher than 20.5 g / m ^ 3. It was. Also in this case, an apparatus configuration as shown in FIG. 13 can be adopted. Of course, other configurations may be used.

1: Photoconductor 2: Charger 3: Exposure means 3a: Laser diode (LD) element 4: Development means 10: Process cartridge 15: Intermediate transfer belt 16: Cleaning counter roller 17: Toner mark sensor (TM sensor)
20: tension roller 21: driving / secondary transfer counter roller 22: transfer material 23: paper feeding / conveying roller 24a: power supply 24b: ammeter 25: secondary transfer roller 31: cleaning blade 32: intermediate transfer belt cleaning unit 33: intermediate Waste toner storage unit 35 for transfer body: Roller 40 for feeding and winding the resistance member 40: Fixing means 51: Next transfer roller 201: Resistance member 701: LD
702: Light receiving unit 703: Laser beam 800: Paper feed tray 801: Transfer material end regulating fence 802: Transfer material end regulating fence moving direction 803: Rotating support member 804: Support unit 805: Guide 900: Manual feed tray 901 Movement direction of transfer material end regulating fence 902: movable support portion 903: gear 904: movable support portion 905: movement direction of second movable support portion θ: angle formed by the support portion

Japanese Patent Laid-Open No. 11-95579 JP 9-325624 A JP 2007-334292 A

Claims (11)

In an image forming apparatus using constant current control as control when a toner image developed on an image carrier or intermediate transfer member is transferred to a transfer material by a transfer unit,
The portion corresponding to a portion other than the main scanning width when the toner image is formed on the transfer material to which the toner image is transferred, and the transfer means and the image carrier or intermediate transfer member are in direct contact with each other. A resistance member sandwiching means for sandwiching the resistance member with respect to at least a part of the portion;
The resistance member pinching means is one while transferring at least the toner image on the transfer material sandwiching said resistor member,
The resistance member is an OHP sheet ;
An image forming apparatus. In an image forming apparatus using constant current control as control when a toner image developed on an image carrier or intermediate transfer member is transferred to a transfer material by a transfer unit,
The portion corresponding to a portion other than the main scanning width when the toner image is formed on the transfer material to which the toner image is transferred, and the transfer means and the image carrier or intermediate transfer member are in direct contact with each other. A resistance member sandwiching means for sandwiching the resistance member with respect to at least a part of the portion;
The resistance member sandwiching means sandwiches the resistance member at least during the transfer of the toner image to the transfer material.
A plurality of process cartridges including a developing device for developing the image carrier and the toner image;
When printing a color image, the developing device forms a toner image on the image carrier with the developing device of each of the process cartridges. When printing a monochromatic image, the developing device of any one of the process cartridges in have line the process,
The resistance member is an OHP sheet ;
An image forming apparatus. In an image forming apparatus using constant current control as control when a toner image developed on an image carrier or intermediate transfer member is transferred to a transfer material by a transfer unit,
The portion corresponding to a portion other than the main scanning width when the toner image is formed on the transfer material to which the toner image is transferred, and the transfer means and the image carrier or intermediate transfer member are in direct contact with each other. A resistance member sandwiching means for sandwiching the resistance member with respect to at least a part of the portion;
The resistance member sandwiching means, while transferred to the transfer material at least the toner image seen come sandwiching said resistor member,
A plurality of process cartridges including a developing device for developing the image carrier and the toner image;
When printing a color image, the developing device forms a toner image on the image carrier with the developing device of each of the process cartridges. When printing a monochromatic image, the developing device of any one of the process cartridges To perform the above steps,
A toner image formed on the image carrier by the developing device is then transferred from the image carrier to an intermediate transfer member composed of an endless belt stretched around a plurality of rollers, thereby forming a color image. Holding, primary transfer means for transferring the toner images for each process cartridge so as to overlap each other;
Secondary transfer means for transferring the toner image on the intermediate transfer member to a transfer material;
The resistance member is an OHP sheet ;
An image forming apparatus. The image forming apparatus according to any one of claims 1 to 3,
An image forming apparatus, wherein the resistance member has a thickness smaller than that of the transfer material . The image forming apparatus according to any one of claims 1 to 4,
An image forming apparatus, wherein the resistance member has a higher resistance than the transfer material . The image forming apparatus according to claim 1 ,
The image forming apparatus, wherein the resistance member has a surface resistance of 9 logΩ / □ or more and 14 logΩ / □ or less, and a volume resistance of 9 logΩ · cm or more and 14 logΩ · cm or less . The image forming apparatus according to any one of claims 1 to 6,
An image forming apparatus comprising a detecting means for detecting the width and thickness of the transfer material. The image forming apparatus according to claim 1,
Transfer material provided with a resistance member moving means for moving the resistance member, and an amount of sliding the resistance member in the main scanning width direction by the resistance member moving means provided in a tray for feeding the transfer material an image forming apparatus comprising same camphor Rukoto a moving amount of the width regulating guides. The image forming apparatus according to claim 1,
An image forming apparatus comprising: interlocking means for interlocking movement of the resistance member by the resistance member moving means with movement of the transfer material width regulating guide . The image forming apparatus according to any one of claims 1 to 9,
Comprising a paper type setting means for setting the paper type of the transfer material, the width dimension of the transfer material can be detected from the paper type set by the paper type setting means,
The resistive member movable means, the image forming apparatus according to claim der Rukoto shall establish the resistance member to a non-paper passing area in the motor drive. The image forming apparatus according to claim 1,
It has a sensor that detects temperature and humidity,
Only when the temperature and / or humidity detected value by the sensor exceeds a predetermined threshold, the resistance member sandwiching means in the transfer material width direction of the image carrier according to the size of the transfer material . An image forming apparatus , wherein the resistance member is sandwiched between the secondary transfer unit and the intermediate transfer material outside a transfer material region corresponding to a transfer width .