JP2003280405A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrences of large defective transfer and partial transfer unevenness at the time of feeding bleached paper under the environments of high temperature and high humidity even when the phenomenon of deteriorated resistance (break-down) due to the high pressure of an intermediate transfer belt is caused in an image forming apparatus having the intermediate transfer belt whose surface layer must be thin so as to possess an elastic layer. <P>SOLUTION: A toner layer is formed of yellow toner on the intermediate transfer belt by previously performing development on an entire image area just before performing normal image formation sequence, and image formation pre-sequence by which the intermediate transfer belt is rotated is performed while holding the layer thereof. That is, the surface of an intermediate transfer body possessing elasticity is thinly filmed with toner by the image formation pre-sequence, so that it is used as protective film for the centralization of currents at an actual processing time. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color analog P
The present invention relates to an intermediate transfer type image forming apparatus such as a PC, a color digital PPC, and a color laser printer.

[0002]

2. Description of the Related Art As an intermediate transfer member used in an intermediate transfer type color image forming apparatus, an intermediate transfer belt made of an elastic material and having a multilayer structure is generally adopted. The intermediate layer of such an intermediate transfer belt is provided with a layer having an apparently low elastic coefficient, and the surface layer is in direct contact with the toner so that the affinity with the toner is low and direct charge injection is prevented. An insulating release layer is arranged. If the surface layer is thick, the elasticity of the intermediate layer cannot be utilized effectively, so the thinner the surface layer, the better.

However, a breakdown phenomenon (resistance reduction phenomenon) may occur in such an intermediate transfer belt. That is, in a general transfer action, if the transfer current is excessive, a strong transfer electric field acts between the transfer belt and the transfer material, and if it is too strong, the transfer rate starts to decrease due to dielectric breakdown. Select a slightly lower bias as the set value. In that case, the current density is about 10 ⁸ V / m. This is the breakdown order of the elastic belt.

In addition to the weak dielectric breakdown strength of the belt material, the breakdown has problems such as voids. Explaining the voids, it is considered that there are minute voids due to bending in the insulating layer / elastic layer of the elastic belt and at the interface, and like the voids (micro voids) in the high voltage wire, the electric field is generated. It is believed that dielectric breakdown progresses with each application.
Such voids are generally considered to grow with the application of an electric field over time. Of course, the mechanical strength of the base material may be insufficient, which may lead to bending cracks. Therefore, although voids are small in the initial state, they are considered to increase with time. Then, it is considered that these defects and reduction in resistance of the base material act on the breakdown phenomenon.

Such a breakdown phenomenon has a problem that the current value is dramatically changed depending on the magnitude of the belt surface potential. For example, if there is uneven resistance in the paper, the current density at that portion becomes high, and the elastic intermediate body breaks down, resulting in a current overload condition at that portion that is more severe than that of the uniform belt. In particular, the resistance of paper may vary depending on the paper type, environment, history, and the like. For example, even if the tray is left in the tray, it may become non-uniform when a circulation path for the outside air is formed in the tray. When such a low resistance portion of the paper enters the transfer nip, the electric potential of the belt surface corresponding to this becomes high, causing breakdown.

As a result of breakdown on the transfer belt side,
Since the current density on the paper side causes the magnitude of the current to be larger than the original resistance unevenness of the paper, an image abnormality occurs in which a bias current shortage and an excess current coexist. Since the smooth paper itself has a weak electric charge holding ability and easily escapes to the surroundings, the adhesiveness is originally poor, and uneven current concentration occurs on the paper, resulting in an image like halation. Further, on the surface where the breakdown has occurred, the resistance is also lowered, so that there is direct charge injection into the toner, and the neighboring toner is positively charged. Further, also on the transfer belt side, there is a problem that the current concentration portion further promotes cracks in the belt.

Similar to the UL layer of the OPC photosensitive member, it has been proposed to prevent current concentration by providing a high resistance insulating layer, but such an insulating layer must be very thin due to its nature, Furthermore, in order to eliminate the residual charge, it is necessary to strictly control the resistance, which is considered to be difficult to realize.

Therefore, normally, from the viewpoint of control, it is possible to prevent the breakdown from progressing completely by setting the bias at a constant current one step before the breakdown occurs, but there is a margin for this variation. Few.

In view of the above-mentioned problems, technically, the aim is to prevent the intermediate transfer belt from being filmed, and the mold releasability is improved.
The inventor of the present application considered that it is technically difficult to form an insulating layer in an intermediate transfer belt having elasticity, and conceived to form a film of a high resistance agent on the surface of the intermediate transfer belt.

That is, according to the present invention, in an image forming apparatus having an intermediate transfer belt which necessarily has a thin surface layer because it has an elastic layer, the resistance lowering phenomenon (breakdown) due to the high pressure of the intermediate transfer belt occurs. It is an object of the present invention to provide a material capable of preventing a large transfer defect or partial transfer unevenness that occurs when a smooth paper is passed under a high temperature and high humidity environment.

[0011]

In order to achieve the above object, the image forming apparatus according to the first aspect of the present invention has a regular image forming sequence in an image forming apparatus using an intermediate transfer member. Immediately before performing the above, the entire image area of the intermediate transfer member is developed in advance to form a toner layer on the intermediate transfer member, and a pre-sequence before image formation is performed to rotate the toner layer. It is characterized by

According to a second aspect of the present invention, in order to achieve the above object, in the image forming apparatus according to the first aspect, the resistance measurement value for each voltage of the intermediate transfer member is higher than the breakdown voltage. The voltage dependency (Ω / V) of the resistance is 10 times or more, and the breakdown voltage is 10 to 25.
It is characterized in that the voltage is set to about 00V.

According to a third aspect of the present invention, in order to achieve the above object, in the image forming apparatus according to the first or second aspect, the absolute humidity of the ambient environment is detected, and the tray is left open after the paper is replenished. It is characterized in that whether or not to activate the pre-sequence is determined based on the coefficient value relating to the time.

According to a fourth aspect of the present invention, in order to achieve the above object, in the image forming apparatus according to any one of the first to third aspects, during the pre-sequence operation, a negatively charged regular image forming apparatus is formed. An electric field in a direction of pushing the toner toward the intermediate transfer body is applied by the secondary transfer means.

According to a fifth aspect of the present invention, in order to achieve the above object, in the image forming apparatus according to any one of the first to fourth aspects, the time when the paper feed tray is opened and the paper feed tray is closed. The present invention is characterized in that the time difference is measured and whether the pre-sequence is input is determined based on the difference value.

According to the sixth aspect of the present invention, in order to achieve the above object, in the image forming apparatus according to any one of the first to fourth aspects, the pre-sequence is introduced for each paper type of transfer material used. Is determined.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the following, an embodiment will be described in which the present invention is applied to a color image forming apparatus that forms an image using an electrophotographic process such as a copying machine or a laser beam printer.

FIG. 1 is a conceptual cross section showing an example of a color image forming apparatus using an intermediate transfer belt. In FIG. 1, a belt-shaped photosensitive member (hereinafter referred to as “photosensitive belt”) 1 as a first image carrier is rotatably stretched by a driving roller 1a, a driven roller 1b, and a primary transfer roller 5. The drive roller 1a is driven and rotated by a drive unit (not shown), so that the drive roller 1a is rotationally driven in the direction of arrow A (clockwise direction) at a predetermined peripheral speed (process speed).

The photosensitive belt 1 is uniformly charged to a predetermined polarity and potential by the primary charging charger 2 during its rotation. Then, an image is exposed on the surface of the photoconductor belt 1 by the exposure means 3 including a scanning exposure system that outputs a laser beam modulated in accordance with the digital pixel signal of the image information. An electrostatic latent image corresponding to the first color component image (for example, a cyan image) of the color image is formed on. This electrostatic latent image is developed by the magenta developing device M which is the first developing device, and the magenta toner which is the first color toner. At this time, the second, third, fourth
The cyan color developing device C, the yellow color developing device Y, and the black color developing device K are in the non-operating state, and the magenta toner image of the first color formed on the photoconductor belt 1 is the second, third, It is set so as not to be influenced by the fourth color developing device.

As the intermediate transfer belt 4, a medium resistance transfer belt (elastic body) is used, which is rotatably stretched by a driving roller 4a, a driven roller 4b, a tension roller 4c, and a secondary transfer counter roller 8. The driving roller 4a is driven and rotated by a driving unit (not shown), so that the driving roller 4a is rotationally driven in the arrow B direction (counterclockwise direction) at the same peripheral speed as the photosensitive belt 1. As described above, when the first color cyan toner image formed on the photoconductor belt 1 passes through the primary transfer portion formed by the photoconductor belt 1 and the intermediate transfer belt 4, the first transfer roller 5 and the photoconductor belt Primary transfer is performed on the surface of the intermediate transfer belt 4 by the transfer electric field formed by the primary transfer bias applied between 1 and 2.

The surface of the photoconductor belt 1 after the transfer of the magenta toner image is cleaned by the photoconductor cleaning device 6. The toner removed by cleaning is collected in the toner collection container 11. Thereafter, as in the case of the first-color cyan toner image, the second-color cyan toner image, the third-color yellow toner image, and the fourth-color black toner image are sequentially superposed on the intermediate transfer belt 4. Primary transfer is performed to form a full-color toner image corresponding to the input color image on the intermediate transfer belt 4. When the toner images of respective colors are sequentially superimposed and transferred from the photosensitive belt 1 to the intermediate transfer belt 4, a bias having a polarity (positive) opposite to that of the toner is applied as a primary transfer bias from a bias power source (not shown). To do. The applied voltage varies depending on the belt resistance of the intermediate transfer belt 4, environmental conditions, etc., but 200V to 1000V is applied, for example.

The secondary transfer roller 7 is installed parallel to the secondary transfer counter roller 8 and is arranged so that it can come into contact with and separate from the intermediate transfer belt 4. The secondary transfer roller 7 and the intermediate transfer belt cleaner 9 are retracted to a position separated from the intermediate transfer belt 4 in the primary transfer process of the first to third colors from the photosensitive belt 1 to the intermediate transfer belt 4. .

The transfer of the full-color toner image primarily transferred onto the intermediate transfer belt 4 onto the transfer material (paper) P is performed by the registration roller 13 at a predetermined secondary transfer position between the intermediate transfer belt 4 and the secondary transfer roller 7. The transfer material P is fed at a timing, the secondary transfer roller 7 contacts the intermediate transfer belt 4, and a secondary transfer bias is applied to the secondary transfer roller 7 from a bias power source (not shown). Then, the full-color toner image is secondarily transferred (collectively transferred) from the intermediate transfer belt 4 to the transfer material P by the secondary transfer bias. Then, the transfer material P to which the secondary-transferred full-color toner image has been transferred is introduced into the fixing device 10, and is fixed as a full-color image by heat fixing.

After the secondary transfer of the full-color toner image to the transfer material P is completed, the cleaning brush of the intermediate transfer belt cleaner 9 is brought into contact with the intermediate transfer belt 4, and the transfer material P is transferred.
The toner (transfer residual toner) remaining on the intermediate transfer belt 4 without being transferred onto the intermediate transfer belt 4 is cleaned. The cleaned transfer residual toner is collected in the toner collecting container 12 provided in the intermediate transfer unit. The intermediate transfer belt cleaner 9 is provided with a fur brush, and a negative bias having the same polarity as that of the toner is applied to clean a part of the toner. The remaining toner has a positive charge, returns to the photosensitive belt 1, and is collected in the cleaning container 11 on the photosensitive belt 1 side.

At the time of forming a full-color toner image, the intermediate transfer belt cleaner 9 is separated from the intermediate transfer belt 4 and comes into contact with it at a predetermined timing to perform cleaning. It should be noted that in the case of monochrome copying such as black, the intermediate transfer belt cleaner 9 can be always brought into contact with the intermediate transfer belt 4 for cleaning. Further, the blade cleaning method of scraping off the toner with a strong force is not suitable as a cleaning method of a transfer unit using an elastic belt because the rotational load of the intermediate transfer belt 4 is increased and the belt surface layer is damaged. Not suitable.

By the way, the intermediate transfer belt 4 has conventionally been made of a fluorine resin, a polycarbonate resin, a polyimide resin or the like, but in recent years, an elastic belt in which all layers of the belt or a part of the belt is an elastic member is also used. Is beginning to do. Generally, the toner layer receives pressure by passing through the primary transfer (transfer from the photosensitive belt 1 to the intermediate transfer belt 4) and the secondary transfer (transfer from the intermediate transfer belt 4 to the transfer material P), and the toner layer The cohesive force between them becomes high. If the cohesive force between the toners becomes high, the phenomenon of hollow characters or missing edges of solid images is likely to occur. Therefore, since the resin belt has a high hardness and does not deform in accordance with the toner layer, the toner layer is likely to be compressed and the hollow character of the character is likely to occur.

Further, recently, there is an increasing demand for forming full-color images on various types of paper, for example, Japanese paper or intentionally providing unevenness or forming an image on the paper. However, a sheet having poor smoothness is likely to cause voids with the toner during transfer, which easily causes transfer failure. If the transfer pressure of the secondary transfer portion is increased in order to improve the adhesiveness, the condensing force of the toner layer is increased, which causes the hollow character as described above.

Since the elastic belt has a hardness lower than that of the resin belt, the elastic belt is deformed corresponding to the toner layer and the paper having a poor smoothness at the transfer portion, that is, the elastic belt is deformed in accordance with the local unevenness. Further, good adhesion can be obtained without increasing the transfer pressure to the toner layer, and a transferred image having excellent uniformity can be obtained even on a paper having no hollow characters and poor flatness.

Resins for elastic belts include polycarbonate, fluororesins (ETFE, PVDF), polystyrene, chloropolystyrene, poly-α-methylstyrene,
Styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-
Maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer And styrene-phenyl acrylate copolymer), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.), Styrene-α-chloromethyl acrylate copolymers, styrene-acrylonitrile-acrylic acid ester copolymers and other styrene-based resins (styrene or styrene-substituted homopolymers or copolymers), methyl methacrylate resins, methacryl Butyl acid resin, ethyl acrylate resin, acrylic Butyl resin, modified acrylic resin (silicone modified acrylic resin, vinyl chloride resin modified acrylic resin, acrylic urethane resin, etc.), vinyl chloride resin, styrene-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer, rosin-modified malein Acid resin, phenol resin, epoxy resin, polyester resin, polyester polyurethane resin, polyethylene, polypropylene,
Polybutadiene, polyvinylidene chloride, ionomer resin, polyurethane resin, silicone resin, ketone resin,
One kind or two or more kinds selected from the group consisting of ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, polyamide resin, modified polyphenylene oxide resin and the like can be used. However, it goes without saying that the material of the intermediate transfer belt targeted by the present invention is not limited to the above materials.

As elastic rubber and elastomer, butyl rubber, fluorine rubber, acrylic rubber, EPDM, NB
R, acrylonitrile-butadiene-styrene rubber natural rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, ethylene-propylene rubber, ethylene-
Propylene terpolymer, chloroprene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, urethane rubber, syndiotactic 1,2-polybutadiene, epichlorohydrin type rubber, recone rubber, fluororubber,
Polysulfide rubber, polynorbornene rubber, hydrogenated nitrile rubber, thermoplastic elastomer (for example, polystyrene type, polyolefin type, polyvinyl chloride type, polyurethane type,
One type or two or more types selected from the group consisting of polyamide type, polyurea, polyester type, fluororesin type) and the like can be used. However, it goes without saying that the material of the elastic layer of the intermediate transfer belt targeted by the present invention is not limited to the above-mentioned material.

The operation of the apparatus according to the present invention will be described with reference to FIG. FIG. 2 shows a pre-image formation sequence (belt surface insulating film formation sequence). As shown in the figure, when a print command is given, the condition at that time is judged (step 1). According to this condition determination, if it is not necessary, the sequence is not input and the regular image sequence is executed (step 13). Although the method for determining the condition in step 1 will be described later, first, if a regular image sequence is required, the photosensitive belt 1 is driven to write an image with a laser,
Alternatively, the grid potential is brought to a level corresponding to the developing potential, the yellow developing device Y is set to the developing position (step 3), and a toner layer is created on the photosensitive belt 1 (step 4: For example, yellow toner is halftone). Write and develop at 40%). These are deposited on the intermediate transfer belt 4 by turning on the primary transfer (step 5). At this time, it is not necessary to increase the primary transfer bias. Then, the secondary transfer roller 7 is connected to the intermediate transfer belt 4
Are contacted with (step 6), and a negative potential is applied thereto (step 7) to rotate (step 8). As a result, the toner is accumulated on the intermediate transfer belt 4 and is in a high Q / M state while adhering. If it is left as it is, the adhesive force is increased and the primary transfer side and the secondary transfer side are pressed, so that it is possible to forcibly give the filming, which is a uniform protective film, to the surface of the intermediate transfer belt 4. Then, the secondary transfer roller 7 is separated from the intermediate transfer belt 4 (step 9), the primary transfer is turned off (step 10), and the cleaning sequence of the photosensitive belt 1 as described above is executed (step 11), The cleaning sequence of the transfer belt 4 is executed (step 12), and then the regular image sequence is executed (step 13).
It should be noted that if this filming is not a mild one, a problem will occur in the next image formation. For that purpose, the primary / secondary voltage and the rotation time may be controlled. For example, primary transfer voltage 1000V, secondary transfer current (for constant current control)-
40 μA, rotation time 1 minute / belt 1 cycle, etc.

The yellow color is used as the image forming pattern because the toner layer formed by the pre-sequence is cleaned before the normal image formation, but the cleaning force is lowered depending on the elasticity of the intermediate transfer belt 4. It is possible that the cleaning failure remains on the intermediate transfer belt 4 in that case, and in consideration of this, the conspicuous color is not used. When a plurality of layers of toner are deposited on the intermediate transfer belt 4, yellow is said to be formed in the order of yellow, magenta, and cyan, and it is also used for tracking patterns. It is convenient because you cannot see the top. Of course, a color other than yellow may be used as long as the cleaning capability of the means for cleaning the intermediate transfer belt 4 is sufficient.

FIGS. 3 to 5 show a flow for determining whether or not the sequence in step 1 of FIG. 2 is to be input. This determination flow is executed during the sequence shown in FIG. First, FIG. 3 and FIG. 4 are executed when a time change of the paper feed sensor or the like is detected, and the time when the target paper feed is unset (Topen, it may be time without paper) and the paper The set time (Tclose) is measured (though not shown in FIG. 1, a tray open / close sensor and a paper feed sensor are used). When there are multiple trays,
The respective data are sequentially stored in the memory as xth.

As shown in FIG. 5, in the routine for determining whether or not the pre-sequence can be inserted, the current time (Tc) is acquired (step 1), and the difference between the current time and the time when the paper is set (Tc-
Tclose time after closing the tray (T
1) and the difference between the current time and the time when the paper feed is unset (T
c-Topen left after opening the tray (T
2) and (steps 2 and 3), and the difference (T2-T1) between the two standing times is set as the standing time (T3) with the tray newly opened, in other words, the tray coefficient. The determination is made by searching the table (step 4). Although not shown in the figure, the table for this propriety determination shows that the time unit is, for example, minutes, and the longest is 999 minutes (actually, the moisture absorption of the paper may be ignored, and it does not change even after being left virtually. ), The above sequence is unnecessary, and a normal image forming sequence is immediately entered together with a print command. If it is less than 999 minutes, the sequence is required and the tray coefficient is confirmed for further determination. . For example, if the leaving time T3 is 2 minutes,
After 2 minutes, the water content of the transfer material exceeds a certain level, and thus the transfer unevenness may occur. Of course, such a table and its value are examples, and other types of tables may be used. For example, it is possible to use a sheet with a classification according to the paper type and absolute humidity table. For example, a pre-sequence is performed by discriminating a sheet that easily absorbs moisture in a high humidity environment such as OHP paper or a sheet that does not easily absorb moisture. You can determine whether to activate.

That is, the standing time T3 (tray coefficient) is measured as an index of how much high humidity around the transfer material inside the tray enters. Highly sealed trays have a high coefficient. In the manual feed tray, almost the entire surface of the transfer material is exposed to the outside, and therefore the coefficient is high even in a leaving time with a short dryness, which is the most severe condition. Therefore, it is possible to set the condition for manually feeding, for example, one transfer material in the manual feed tray as one unit, and to expect the smoothness durability of about 10 times in a normal paper feed tray. Of course, such a setting is merely an example, and it is necessary to conduct various experiments to determine the values to be tabulated.

As a result, the time (minutes) that becomes the threshold value for introducing the above-described pre-sequence becomes a value Ts obtained by multiplying the absolute humidity (AH) and the numerical value obtained from the paper type by the tray coefficient. The absolute humidity (AH) can be measured with a temperature / humidity sensor or the like. If the actual standing time after setting the paper (T1) is longer than this value Ts, the pre-sequence must be turned on, and the time when the tray is left open (T3) is naturally the same. Is. In these cases, the tray is half-opened, and the paper condition is significantly deteriorated.

When the judgment conditions are quantified and judged as described above, it is possible to take measures even when the exposure is effective for a long time even at a moderate humidity. It should be noted that the above-described measurement is of course performed while the image forming apparatus is operating, but the user may turn off the power of the image forming apparatus during measurement. May separately perform prediction and handle the pre-sequence accordingly.

[0038]

As described above, in the image forming apparatus according to the first aspect of the present invention, in the image forming apparatus using the intermediate transfer member, the entire image area is developed in advance just before executing the regular image forming sequence. Perform a pre-imaging pre-sequence in which the toner layer is formed on the intermediate transfer body, and the intermediate transfer body is rotated while holding this layer, and the toner is lightly applied to the elastic intermediate transfer body surface by the pre-image formation pre-sequence. By filming and using it as a protective film against current concentration during the actual process, it is possible to prevent the transfer material that has been exposed to high temperature and high humidity from leaking to the intermediate transfer belt when it passes. Although it is difficult to really predict the condition of saliva, it is effective to prevent leakage to some extent.

As described above, the image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, in which the resistance measurement value at each voltage of the intermediate transfer member is higher than the breakdown voltage. Voltage dependence (Ω / V) of 10 times or more and the breakdown voltage is 10 to 2500
Since it is set to about V, in addition to the common effects described above,
A protective film can be temporarily formed on the intermediate transfer body side against current concentration and current shortage when using a transfer material that is exposed to high humidity and uneven resistance due to this voltage condition at the same time. There is an effect that a bad image defect can be prevented. This is less of a problem when using an intermediate transfer belt having no voltage dependence, but it is effective when using a belt material that is easily affected by the temperature and humidity environment.

As described above, the image forming apparatus according to the third aspect detects the absolute humidity of the surrounding environment, and based on the coefficient value relating to the time when the tray is left open after the paper is replenished, Since it is determined whether or not to activate the sequence, in addition to the common effects described above, a pre-sequence can be input only when necessary, and determination is made based on a table in which coefficient values are set in advance. This has the effect that the pre-sequence can be activated only when it is really needed, and the decrease in output throughput can be minimized.

As described above, in the image forming apparatus according to the fourth aspect, during the pre-sequence operation, the electric field in the direction of pushing the negatively charged regular toner for image formation to the intermediate transfer body side is secondarily transferred. In addition to the common effects described above, it becomes easy to form a protective film on the intermediate transfer member by pre-sequencing, and unlike the normal transfer, negative charge is applied to the negatively charged toner. Therefore, the toner can be easily retained in a film shape without turning off the primary transfer or charging the image bearing member such as the photoconductor.

As described above, the image forming apparatus according to the fifth aspect measures the difference between the time when the paper feed tray is opened and the time when the paper feed tray is closed, and based on the difference value. Since it is determined whether or not to input the pre-sequence, in addition to the common effects described above, the pre-sequence can be activated when there is a large amount of transfer material that is partially exposed when the paper feed tray is half opened. There is an effect.

As described above, the image forming apparatus according to the sixth aspect of the invention determines whether or not to input the pre-sequence for each paper type of the transfer material to be used. For example, there is an effect that it is possible to operate the pre-sequence by discriminating a material that easily absorbs moisture in a high humidity environment such as OHP paper or a material that hardly absorbs moisture such as thick paper.

[Brief description of drawings]

FIG. 1 is a conceptual cross section showing an example of a color image forming apparatus using an intermediate transfer belt.

FIG. 2 is a flowchart showing a pre-image formation sequence (belt surface insulating film formation sequence) according to the embodiment of the present invention.

FIG. 3 is a flowchart for determining whether or not to input the sequence of FIG.

FIG. 4 is another flowchart for determining whether or not to input the sequence of FIG.

FIG. 5 is a flowchart showing a routine for determining whether or not to input a pre-sequence.

[Explanation of symbols]

1 photoconductor belt 2 Primary charging charger 3 exposure means 4 Intermediate transfer belt 5 Primary transfer roller 6 Photoconductor cleaning device 7 Secondary transfer roller 8 Secondary transfer counter roller 9 Intermediate transfer belt cleaner 10 Fixing device 11, 12 Toner collection container 13 Registration roller M magenta developer C Cyan color developing device Y Yellow color developing device K black color developing device P Transfer material (paper)

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H027 DA14 DA38 DC02 DE07 DE09                       EA20 EC06 EC14 ED24 EE01                       EF06                 2H200 FA09 GA10 GA24 GA34 GA47                       GA50 GB12 GB22 GB26 HA02                       HA12 HA28 HB03 HB12 JA02                       JA28 JC03 JC07 JC12 JC15                       JC16 JC17 LA24 LB02 LB03                       LB08 LB12 LB18 MA03 MA04                       MA20 MB02 MC01 NA02 NA08                       NA09 PB25 PB28 PB35

Claims (6)

[Claims] 1. In an image forming apparatus using an intermediate transfer member, immediately before performing a normal image forming sequence, the entire image area of the intermediate transfer member is developed in advance to form a toner layer on the intermediate transfer member. An image forming apparatus, which is configured to perform a pre-sequence before image formation in which the toner layer is rotated. 2. The image forming apparatus according to claim 1, wherein the resistance measurement value for each voltage of the intermediate transfer member has a voltage dependence (Ω / V) of resistance of 10 at a voltage higher than a breakdown voltage.
More than double and the breakdown voltage is 10 to 2
An image forming apparatus, wherein the image forming apparatus has a voltage of about 500V. 3. The image forming apparatus according to claim 1, wherein the pre-sequence is operated based on a coefficient value related to the time when the absolute humidity of the surrounding environment is detected and the tray is left open after paper is replenished. An image forming apparatus, characterized in that it is configured to determine whether or not to press. 4. The image forming apparatus according to claim 1, wherein during the pre-sequence operation, an electric field in a direction in which the negatively charged regular toner for image formation is pushed toward the intermediate transfer body is secondarily transferred. An image forming apparatus, characterized in that the image is applied by means. 5. The image forming apparatus according to claim 1, wherein the difference between the time when the paper feed tray is opened and the time when the paper feed tray is closed is measured, and based on the value of the difference. An image forming apparatus, wherein it is determined whether or not to input the pre-sequence. 6. The image forming apparatus according to any one of claims 1 to 4, wherein it is determined whether or not to insert the pre-sequence for each type of transfer material used. .