JPH0611978A - Image forming device - Google Patents

Abstract

PURPOSE:To always provide excellent image of uniform concentration even though a recording material support means having dispersed physical values is used. CONSTITUTION:A recording material supporting belt previously mounted to a copying machine is rotated so as to measure volume resistivity at every 100mm movement and store it into RAM, and when a toner image formed on a photosensitive drum is transcribed onto the recording material supported and transported by the recording material supporting belt, the data of the recording material supporting belt stored in the RAM is read out according to a belt position signal, and optimum transcribing current I0 in response to the resistance value in a position at every 100mm of the supporting belt is impressed on the transcribing electrifier of a transcribing part. At this time, the transcribing current I0 is corrected according to the sort of the recording material, and further when data stored in the RAM is not corrected by the device environment, the transcribing current I0 is corrected according to the device environment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic system in which a visible image is formed on an image carrier and the visible image is transferred onto a recording material (recording medium) carried by a recording material carrying means.
With respect to an image forming apparatus such as an electrostatic recording system, for example, but not limited to, a visible image of a plurality of different colors is formed on an image carrier, and these visible images are carried and conveyed by a recording material carrying means. The present invention is suitable for a color image forming apparatus such as a color copying machine or a color printer, which is configured so as to be successively transferred onto the same recording material.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus having a plurality of image forming sections, forming toner images of different colors in each image forming section, and successively transferring these toner images onto the same recording material, Various so-called color image forming apparatuses have been proposed. Among them, the electrophotographic color image forming apparatus is widely used. In such an electrophotographic color image forming apparatus, a plurality of image forming units, generally four image forming units are arranged side by side, and a dedicated photoconductor drum is used as an image carrier of these image forming units. Cyan, magenta, yellow, and black visible images, that is, toner images are separately formed on the drum, and are sequentially recorded on the recording material that is carried and conveyed by the recording material carrying means such as a dielectric belt. Toner images are superposed and transferred, and the multiple toner images on the recording material are collectively heat-fixed by a fixing device to obtain a desired full-color image or multi-color image.

An example of such an electrophotographic color image forming apparatus, a color copying machine in this example, will be briefly described with reference to FIG. This color copying machine has a structure in which four image forming sections Pa, Pb, Pc and Pd are linearly arranged in the main body of the apparatus, and each of the image forming sections Pa to Pd is a dedicated photosensitive member as an image carrier. Body drums 1a, 1b, 1c
And 1d respectively, and there are dedicated image forming process means around the photosensitive drums 1a to 1d, respectively.
For example, the latent image forming units 2a, 2b, 2c, 2d, the developing unit 3
a, 3b, 3c, 3d, and the cleaning units 5a, 5
b, 5c, 5d, etc. are provided.

On the other hand, under the photosensitive drums 1a to 1d of the image forming sections Pa to Pd, an endlessly moving recording material carrying belt 8 is arranged in a stretched state between a pair of rollers 10 and 11. Inside the transfer parts 4a, 4b, 4c, 4d
Further, a sheet feeding device including a recording material cassette 60 for storing the recording material 6 is arranged on the right side of the recording material carrying belt 8 in the drawing. Further, a registration roller pair 13 for feeding the recording material 6 at a timing is arranged between the paper feeding device and the recording material carrying belt 8,
The recording material 6 is held on a recording material carrying belt 8 from a paper feeding device via a pair of registration rollers 13 and is sequentially conveyed to the image forming portions Pa to Pd as the belt 8 moves.

In the above structure, first, the recording material 6 delivered from the recording material cassette 60 is temporarily stopped when its front end is slightly sandwiched by the pair of registration rollers 13, and the recording material 6 of the first image forming portion Pa is stopped. It is sent out at the same timing as the image forming process, and is fed onto the recording material carrying belt 8. In the first image forming portion Pa, the photosensitive drum 1 uniformly charged by the latent image forming portion 2a.
Image information of the cyan component color in the original image is scanned with respect to a by a laser beam or the like to form an electrostatic latent image of the cyan component color. Cyan toner is attached to the electrostatic latent image at the developing section 3a to form a visible cyan image.

On the other hand, the recording material 6 is carried on the recording material carrying belt 8 and conveyed, and in the transfer area below the photosensitive drum 1a of the first image forming portion Pa, the operation of the transfer charging means of the transfer portion 4a is performed. Thus, the visible cyan image, that is, the toner image formed on the photosensitive drum 1a is transferred onto the recording material 6. While the cyan toner image is thus transferred onto the recording material 6, an electrostatic latent image of magenta component color is formed in the second image forming portion Pb, and this electrostatic latent image is magenta in the developing portion 3b. It is a toner image, and the recording material 6 is the second image forming portion P.
When the magenta toner image is conveyed to the lower transfer area of the photosensitive drum 1b of b, the magenta toner image moves to the transfer area and is superposed on the cyan toner image on the recording material 6 by the action of the transfer charging means of the transfer section 4b. Will be transcribed.

Hereinafter, the third and fourth image forming portions Pc and Pd will be described.
Even in this case, similarly to the first and second image forming portions Pa and Pb, yellow and black toner images are sequentially formed,
These toner images are sequentially transferred in multiplex onto the recording material 6 conveyed by the recording material carrying belt 8.

When the image forming process is completed, the recording material 6 is separated from the recording material carrying belt 8 and fixed to the fixing device 7.
Then, the desired full-color image is obtained by batch fixing. Further, the residual toner is removed from the photosensitive drums 1a to 1d of the image forming portions Pa to Pd after the transfer is completed by the cleaning portions 5a to 5d to prepare for the subsequent latent image formation. On the other hand, dirt on the recording material carrying belt 8 is removed by the belt cleaning device 9. As a cleaning means of the cleaning device 9, a blade, a fur brush, or both of them are used in most cases.

Here, the recording material carrying belt 8 is made of polyurethane resin, polycarbonate resin, polyethylene terephthalate resin, polyether sulfone resin, polyvinylidene fluoride resin or the like, or carbon is mixed into these resins to adjust the resistance. Thickness of 50-500μ
It is a film of a dielectric resin having a thickness of about m, and both ends thereof are overlapped and joined to each other to form an endless shape, or a seamless belt is used.

When the carrying belt 8 starts to rotate, the recording material 6 is fed from the registration roller 13 onto the carrying belt 8. At this time, the image writing signal is turned on, and the above-described image is formed on the photosensitive drum 1a of the first image forming portion Pa at a certain timing. And
When the recording material 6 reaches the lower side of the photosensitive drum 1a, the toner image on the photosensitive drum 1a is transferred and an image is formed on the recording material 6. It is strongly electrostatically adsorbed on the carrier belt 8. Therefore, the color copying machine shown in FIG. 4 does not use an adsorption system for adsorbing the recording material 6 on the carrier belt 8.

On the other hand, since the recording material 6 is adsorbed on the carrier belt 8, an electric charge is applied to the carrier belt 8 in advance, or the recording material 6 is fed onto the carrier belt 8 at the same time. An image forming apparatus using an adsorption system or the like for imparting is also proposed.

However, in these adsorption systems, in a recording material having a low resistance, a high humidity environment in which the recording material has a low resistance, or the like, the interaction between the recording material adsorbing portion and the first image forming portion occurs. However, there are drawbacks such as an image being distorted, an image is disturbed, and a high pressure for adsorption is used, resulting in a large power consumption and an increase in cost. Also, a method of separating the suction portion and the first image forming portion has been proposed in order to eliminate the above-mentioned interaction, but there is a drawback that the apparatus becomes large.

Therefore, since the interaction does not occur, it is not necessary to separate the suction portion and the first image forming portion, and a loop is easily formed when the recording material is fed from the registration roller to the recording material carrying belt. Further, an image forming apparatus using no adsorption system as shown in FIG. 4 which has an advantage that a compact and stable system is easy to make has been proposed and put into practical use.

In the color copying machine having the above structure, however, the conventional transfer method uses recording material, recording material carrying means (recording material carrying belt, etc.) by using control based on recording material, environment-based control such as temperature and humidity. It was common to apply a transfer current that is optimum for the physical properties of the medium (intervening between the energy applying unit that contributes to the transfer and the recording material) during transfer.

[0015]

However, in the above-mentioned conventional example, like the recording material carrying belt 8 shown in FIG. 4, at the time of transfer, there is an interposition between the recording material and the electric energy applying means that contributes to the transfer. If the medium to be used has variations in physical properties (volume resistivity, surface resistivity, thickness, dielectric constant, etc.), it has a drawback that it affects the image after transfer.

Further, in the above-mentioned conventional example, when unevenness on the image such as density unevenness in the direction perpendicular to the recording material conveyance direction (hereinafter referred to as the main scanning direction) occurs, the accuracy of the apparatus,
There was no other way than increasing the accuracy of the parts. In particular, in an image forming apparatus that transfers an image to a recording material via a recording material carrying means to form a print image, when the recording material carrying means controls electric conductivity by mixing two or more components. However, there is a drawback that the volume resistivity also varies due to this unevenness of mixing, resulting in uneven density on an image. The unevenness (variation) at the time of mixing is likely to occur in the direction perpendicular to the extrusion direction during extrusion molding, for example. Therefore, in the past, the direction with many variations could not be used as the main scanning direction. Further, even if the main scanning direction is a direction in which there is little variation in composition during mixing, even a slight variation causes image unevenness, so it was treated as a defective product and could not be used.

When a belt having a seam is used as the recording material carrying belt 8, the resistance value is changed at the seam due to a change in physical properties due to melting of the belt material and a step difference (thickness change) due to overlapping of end portions. Since it changes and a linear defective image is generated at the seam, the seam must be a non-image area at the time of image formation.

Therefore, one object of the present invention is to use a recording material carrying means having various physical property values by controlling the transfer conditions according to the measurement position of the physical properties contributing to the transfer of the recording material carrying means. Even more, it is an object of the present invention to provide an image forming apparatus that can always obtain a good image with uniform density.

Another object of the present invention is to prevent the charging of the recording material holding means by controlling the charge elimination condition of the recording material holding means, and to make uniform even if the recording material holding means having a variation in physical property value is used. An object of the present invention is to provide an image forming apparatus that can always obtain an image with good density.

Still another object of the present invention is to use a transfer charging means in which a plurality of electrodes are arranged in the main scanning direction, and control the transfer energy applied in the arrangement direction of these electrodes to obtain physical property values. An object of the present invention is to provide an image forming apparatus capable of always obtaining a good image having a uniform density even if a recording material carrying means having variations is used.

[0021]

The above object is achieved by the image forming apparatus according to the present invention. In summary, according to the first aspect of the present invention, an image carrier and a recording material on which a visible image formed on the image carrier is transferred are carried to a transfer position of the image carrier. Recording material carrying means for conveying,
An image forming apparatus comprising: an energy application unit that applies energy contributing to transfer to the recording material via the recording material supporting unit at the transfer position to transfer a visible image on the image carrier to the recording material. In, the physical properties that contribute to the transfer of the recording material carrying means are measured in the image forming apparatus, and the measured values are stored corresponding to the measurement positions of the recording material carrying means, and are stored at the time of image formation. The image forming apparatus is characterized in that the transfer condition is controlled by the position of the recording material carrying means based on the measured value.

Further, in the second aspect, the present invention provides
An image carrier, a recording material carrier that carries a recording material on which a visible image formed on the image carrier is transferred, and conveys the recording material to a transfer position of the image carrier, and the recording material at the transfer position. An image forming apparatus comprising: an energy applying unit that applies energy contributing to transfer to the recording material via a carrying unit to transfer a visible image on the image carrier to the recording medium. The physical properties that contribute to the transfer of the recording medium are measured outside the image forming apparatus, and the measured values are stored in the non-volatile storage unit corresponding to the measurement position of the recording material holding unit, and are stored in the storage unit during image formation. The image forming apparatus is characterized in that the transfer condition is controlled by the position of the recording material carrying means based on the measured value.

In a third aspect, the present invention provides
An image carrier, a recording material carrier that carries a recording material on which a visible image formed on the image carrier is transferred, and conveys the recording material to a transfer position of the image carrier, and the recording material at the transfer position. An image forming apparatus comprising: an energy applying unit that applies energy contributing to transfer to the recording material via a carrying unit to transfer a visible image on the image carrier to the recording medium. The image forming apparatus is characterized by storing physical property values that contribute to the transfer of the recording medium, and controlling the charge removal condition of the recording material holding means based on the stored data.

Further, in a fourth aspect of the present invention, the present invention carries an image carrier and a recording material on which a visible image formed on the image carrier is transferred to the transfer position of the image carrier. And a recording material carrying unit that conveys a recording material carrying means for transferring a visible image on the image carrying body to the recording material by applying energy that contributes to transfer to the recording material through the recording material carrying means at the transfer position. In the image forming apparatus including an applying unit, the energy applying unit has a configuration in which a plurality of electrodes are arranged in a direction perpendicular to the conveying direction of the recording material, and transfer energy to be applied in a direction in which these electrodes are arranged. The image forming apparatus is characterized by being controlled.

[0025]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following embodiment is a case where the present invention is shown in FIG. 4 and is applied to the above-mentioned electrophotographic color copying machine, and therefore the description of the configuration and operation of the color copying machine will be omitted unless necessary. However, the present invention is equally applicable to image forming apparatuses of various configurations other than the embodiment, such as an electrophotographic system and an electrostatic recording system.

FIG. 1 is a flow chart showing the sequence of the control operation of the first embodiment of the present invention. Data obtained by measuring the volume resistivity of the recording material carrying belt 8 mounted on the color copying machine shown in FIG. Shows the operation when the transfer current as transfer energy is controlled by. In this embodiment, the recording material carrying belt 8 has a width of 350.
An endless seam belt was used in which a polyurethane having a diameter of 1000 mm, a circumference of 1000 mm, and a thickness of 0.13 mm was provided with a seam of 2 mm.

When manufacturing such a large belt by extrusion molding, generally, when the pulling-out direction is the main scanning direction, there are large variations in thickness, electrical resistance, composition, etc. in the sub-scanning direction. Occurs. Therefore, in the present embodiment, variations in the sub-scanning direction that occur during belt manufacturing are corrected in the apparatus, and even if there are variations in the physical properties of the recording material carrying belt 8 in the sub-scanning direction as described above, a uniform density is obtained. This is so that a good image can always be obtained.

In this embodiment, as shown in FIG.
The apparatus is set to the belt data measurement mode, the recording material carrying belt 8 is rotated once to sufficiently remove the charge (step S
1). During this time, the belt 8 is at a predetermined position (starting point of the belt)
Is detected (step S2). Then, the transfer current is applied to the transfer chargers of the transfer portions 4a to 4d from a predetermined position of the second rotation (step S3). Here, the predetermined position is
It may be anywhere on the belt, such as a seam, but for example, in the case of a method of reading one mark on the belt and calculating the belt position from time and rotation speed, the method that corrects the mark from the recognized position is the most error. Is less and preferable.
In the present embodiment, a recognition mark (not shown) is marked on the belt joint, and data is taken in from a point 100 mm ahead in the belt rotation direction (step S4). The data may be the current I flowing in the direction of the photosensitive drums 1a to 1d when the transfer current is applied to the transfer charger. Since a corotron charger is used as the transfer charger in this embodiment, I = I ₀ − if the current flowing in the shield plate direction of the corotron charger is I ′ with respect to the applied current I _0.
The relationship of I'is established. That is, although the current I may be directly measured, the current I flowing in the direction of the photosensitive drum can be known by measuring the current I ′ flowing in the direction of the shield plate. Therefore, in this embodiment, as shown in step 4, the current I ′ flowing in the shield plate direction is measured from a predetermined position of the carrying belt 8 and is measured every 100 mm in the moving direction.

The applied current I ₀ is 510 μA divided by 256 every 2 μA according to a digital signal in the apparatus. For example, 200 μA is 64H. FIG. 2 shows the relationship between the currents I, I ₀ and I ′ in this embodiment. In FIG. 2, the current I'on the horizontal axis is the value when I ₀ = 200 μA. Usually, when a recording material carrying belt of 7 × 10 ¹³ Ω · cm is used, the straight line in the figure is obtained in an environment of temperature 25 ° C. and humidity 60%. There is a variation in resistance of the recording material carrying belt, and when the resistance is low, the straight line moves to the straight line side in the figure, and when the resistance is high, the straight line moves to the straight line side in the figure. That is, the higher the resistance, the smaller the current I flowing in the direction of the photoconductor drum even if the same current I ₀ is applied.

As described above, in this embodiment, 64H
Since the current I ′ toward the shield plate is measured with respect to the applied current I ₀ of (= 200 μA), the current of I = 15 μA and I ′ = 185 μA flows in the normal state of the straight line. Also, on a straight line of low resistance, I = 20 μA, I ′ =
A current of 180 μA flows, and further, a current of I = 12 μA and I ′ = 188 μA flows on a high resistance straight line.

When the currents I, I ₀ and I'can be measured in this way, they are associated with the resistance value R of the recording material carrying belt 8. This is shown in FIG. In FIG. 3, the vertical axis represents the logarithm (log) of the resistance value R [Ω · cm] of the recording material carrying belt 8.
R), and the horizontal axis is the ratio of the currents I and I ₀ (I / I ₀ ). In the relationship shown in FIG. 3, I / I ₀ changes depending on each device, but the shape of the charger is particularly important. This Figure 3
The resistance value R of the corresponding belt can be obtained from the above relationship, and data is stored in the memory so that the optimum current I ₀ for that resistance value can be applied to the transfer charger. In this embodiment, logR shown on the vertical axis of FIG. 3 is used as data, and R
Data is input to AM (random access memory). According to this data, an optimum current I ₀ may be applied to the transfer charger according to the belt position signal, the type of recording material, and the environment of the apparatus.

In this embodiment, in step S5, the average value of the measured current I'for every 100 mm is obtained after the carrier belt 8 has been rotated twice, and the current ratio I / I ₀ is obtained from this.
LogR, which is the vertical axis of FIG. 3, is calculated. Next, in step S6, the calculated logR for every 100 mm is input and stored in the RAM as data, and the belt data measurement mode ends. At this time, log every 100 mm
The R data may be stored in the RAM after being corrected by the environmental signal (temperature and humidity).

Next, when the electrostatic latent image is formed on the photosensitive drums 1a to 1d from the image signal according to the normal sequence and is developed into a toner image, and the toner image is transferred to the recording material 6, the RAM is used. 10 of the recording material carrying belt 8 stored in
The data for each 0 mm is read from the corresponding address of the RAM in accordance with the belt position signal, and 100 of the carrying belt 8 is read.
An optimum transfer current I ₀ corresponding to the resistance value at each position of mm is applied to the transfer chargers of the transfer units 4a to 4d. At this time, the transfer current I ₀ is corrected according to the type of recording material, and RA
When the data stored in M is not corrected by the device environment, the transfer current I ₀ is corrected according to the device environment. Thus, even if there are variations in the physical properties of the recording material carrying belt 8 in the sub-scanning direction, it is possible to always output a good image with uniform density.

Note that the distance in the moving direction of the recording material carrying belt 8 for measuring the current is not limited to 100 mm, and it is essential that the distance is such that a good output image with uniform density can be obtained.

In the above embodiment, the resistance value at each position in the moving direction of the recording material carrying belt is calculated and the optimum transfer current I ₀ is applied, but in addition to this,
Furthermore, a second embodiment of the present invention in which the surface potential of the recording material carrying belt is also included in the control requirements will be described.

In this case, a potential sensor for measuring the surface potential of the recording material carrying belt 8 is required. It is desirable that the potential sensor is installed at a position between the belt cleaning device 9 and the recording material 6 being fed. This is because the recording material carrying belt 8 may be charged by friction with the brush or blade in the belt cleaning device 9. In the color copying machine having the configuration shown in FIG. 4, the above position was closest to the belt potential when the recording material was transferred. This depends on the device,
In this example, there was almost no difference from the potential measured at the position of the photosensitive drum 1a in the first image forming portion Pa.

Further, in this embodiment, the recording material carrying belt 8
The transfer current is not controlled in real time by the surface potential of 1 above, but the transfer current is controlled by the average potential before one rotation. Therefore, before the image formation, for example, before the fixing roller of the fixing device 7 reaches a predetermined temperature, or during the preparation time such as the time for monitoring the potential on the photosensitive drum before the latent image formation, the recording material The carrier belt 8 is pre-rotated, and the relative charge amount V of the belt is detected by the average value for one round of the belt at that time. With respect to this average value, the transfer current I ₀ calculated from the data in the RAM is increased or decreased by one round of the carrying belt. This correspondence is shown in FIG. That is, when the belt charge amount V is −V ₁ , it is 1.0
5I _0, and 0.9 when the belt charge amount V is + V _1.
5I ₀ . As described above, when the surface of the recording material carrying belt 8 is charged due to poor charge removal or the like, an appropriate current I cannot be obtained unless the transfer current I ₀ is applied correspondingly. This leads to an increase in the transfer current I ₀ during multicolor and multiple transfer.

Generally, the surface potential of the recording material carrying belt is not suitable as a parameter for real-time control due to many noises and fluctuations. However, by using the average value of several revolutions as the parameter as in the present embodiment. , Has solved this problem. Further, by adding the electric potential as a parameter to the control of the first embodiment, a more appropriate transfer current I ₀ can be applied to each belt position.

Here, it is not always necessary to save the average value of the surface potential (here, this is the charge amount) as data for each recording. When a plurality of photoconductor drums are provided as in the copying machine shown in FIG. 4, preliminary rotation is performed in order to suppress variations in the potential on each drum, and the potential is measured during that period. Further, in order to set the position of the recording material carrying belt to a position suitable for recording (such that the seam of the belt does not affect the recorded image), preparatory rotation is required. By measuring the potential at this time, the time required for the first copy was not particularly reduced.

Next, a third embodiment of the present invention in which the thickness of the recording material carrying belt 8 is used as a parameter will be described.

Generally, the hygroscopicity (water absorption) of the low resistance portion and the high resistance portion of the carrier belt does not change much depending on the environment in which the device is placed, and the resistance-current difference as shown in FIG. In many cases, one conversion table is sufficient for engineering plastics. However, when there is extreme unevenness during mixing or when the coating material is extremely uneven, it is possible to perform more preferable control by providing two or three conversion tables as shown in FIG. 6, depending on the environment. There is. Further, in the above embodiment, the control was performed by the electric characteristics such as the surface potential and the volume resistivity, but in addition to this, the control using the electric current such as the adsorption current or the transfer current, the surface resistivity and the dielectric constant as parameters is also possible. Although possible, the characteristics of the belt other than the electrical characteristics such as the thickness of the belt can be controlled as parameters.

For example, when the carrier belt 8 is made of a polycarbonate resin in which a conductive material such as carbon is dispersed, the thick portion of the belt has a low resistance value and the thin portion has a high resistance value. It tends to be resistance. Further, with polyvinylidene fluoride (PVdF) or the like, a thick portion of the belt has a high resistance and a thin portion has a low resistance. As described above, although the characteristics differ depending on the material and the manufacturing method, the thickness at each position of the belt is associated with the resistance value of the belt with respect to such variations, and the optimum conversion is performed as shown in FIG. The transfer current can be determined.

Therefore, in this embodiment, the linear conversion table of FIG. 6 is used in the standard environment of temperature 25 ° C. and humidity 60%, and in the environment of temperature 35 ° C. and humidity 90%, the low resistance portion absorbs water. , The water absorption becomes worse in the high resistance part, and the resistance becomes even lower in the low resistance part as shown by the straight line, so the transfer current is lowered from the standard applied current, and conversely in the high resistance part, it is slightly lower than the standard applied current. Apply a large amount of transfer current.
At the belt resistance ratio r = 1.0, the standard current is set to 1.0 in any environment.
It will always be 1.0.

Further, it goes without saying that instead of the control for setting the standard applied current according to the environment, a control method for selecting the conversion table according to the environment as shown by the straight line in FIG. 6 may be used.

As in this example, the belt thickness measurement, etc.
If the transfer current can be controlled by measuring the physical property values that are relatively trouble-free, it is possible to bring about a great effect on cost reduction especially when the recording material carrying belt 8 is mass-produced.

Further, it is very difficult to measure the thickness of the belt accurately during the normal image forming sequence,
If the present invention is applied, a data measurement mode is provided, and at the time of measuring the thickness of the belt, the belt portion sufficiently cleaned by the cleaning device is sequentially stopped, and data can be acquired at arbitrary measurement intervals. As described above, parameters that are not suitable or impossible for real-time control can be used in the present invention.

In each of the above embodiments, the control of the transfer current is explained, but the control of the transfer voltage is not limited to the current control such as the control of the transfer voltage in the voltage control. Also,
Type of recording material (recording medium) (for example, 80g paper and OHP
It is known to control transfer conditions by means of a film or the like), but the standard transfer current value I _N can be determined according to the type of recording material. In this case as well, the same control as in the above-described embodiment can be performed, and this will not be described in detail, but is included in the scope of the present invention.

Next, the fourth and fifth embodiments of the present invention will be described.

FIG. 7 is a flow chart showing the sequence of the control operation of the fourth embodiment of the present invention, in which the volume resistivity is measured before the recording material carrying belt 8 is mounted on the color copying machine shown in FIG. It shows the operation when the transfer current as the transfer energy is controlled by the above data. In the flowchart of FIG. 7, the process shown by the dotted line shows the operation outside the machine, and the process shown by the solid line shows the operation inside the machine.

In order to enable the color copying machine shown in FIG. 4 to record up to A3 size, at least about 300 m
A belt width of m is required. In this embodiment, the recording material carrying belt 8 is made of polyurethane having a width of 350 mm, a peripheral length of 1000 mm and a thickness of 0.13 mm, as in the above embodiment.
An endless seam belt provided with a mm seam was used.

As described above, when manufacturing such a large belt by extrusion molding, generally, when the drawing direction is the main scanning direction, the thickness, volume resistivity, etc. in the sub scanning direction are Variation greatly occurs. Therefore, in this embodiment, as shown in step S11, the volume resistivity of the belt is measured at intervals of 10 mm after the belt is manufactured and before being incorporated in the apparatus. The optimum volume resistivity for such a recording material carrying belt 8 is 10 ¹⁴ to 10 ¹⁵ Ω · c.
It is of the order of m, and the amount of deviation from this standard value is input as data to a ROM (Read Only Memory) in step S12. This ROM is mounted on the copying machine (step S13), and the ROM data is read into the control section (for example, CPU) of the copying machine (step S14).

On the other hand, the transfer current is an optimum applied current depending on the environment where the apparatus is placed (constant current control is taken as an example here,
It is known that the applied voltage is different during constant voltage control, as previously proposed. Therefore, an environment sensor (temperature / humidity sensor) is provided in the apparatus (step S15), and the standard applied current at the time of transfer is determined in step S16 by the signal from the temperature / humidity sensor.

By the way, in order to adapt the copying machine to various environments, all the categories are classified according to each environment (temperature and humidity). The classification changes the transfer current when the recording material carrying belt is as set. Measure the volume resistivity in each of the environmental categories) and let the deviation from the standard value be R
There is also a method of using OM data. However, it is unreasonable to measure and store each environmental data in such a way because of the labor, time and cost.

Therefore, in this embodiment, the volume resistivity in a certain environment (for example, temperature 23 ° C., humidity 60%) is measured, and the deviation amount from the standard value is used as ROM data in step S12. The above-mentioned characteristic diagram of FIG. 6 is a graph showing the relationship between the ROM data and the deviation amount of the standard applied current at the time of transfer determined from the signal of the temperature and humidity sensor with respect to the optimum transfer current.

The vertical axis of FIG. 6 shows the ratio of the volume resistivity of the recording material carrying belt 8 in logarithm (log). In this example, the standard value (1.0) is the volume resistivity R of R = 7 ×. 10 ¹³ Ω ・ c
m. That is, the belt resistance ratio r (r = log ₁₀ R)
Is 1.0 when the transfer current ratio i = 1.0, and R = 7 ×
It is 10 ¹³ Ω · cm. The value of this R is a temperature 25 ° C., are those measured at 60% humidity environment, the standard transfer current value I _N at this time is 225Myuei, transfer current ratio i is
i = I / _IN = I / 225.

Here, when the environment is high temperature of 35 ° C., humidity of 90% and high humidity, I _N = 75 μA and temperature of 15
I _N = 300μA at low temperature and humidity of 5 ℃
And the signal from the temperature and humidity sensor, the standard transfer current value _IN
The following describes a case where the resistance value R of the recording material carrying belt 8 has a variation of 1 × 10 ¹² to 2 × 10 ¹⁵ Ω · cm in the apparatus in which the value changes.

In the environment of 25 ° C. and 60%, R = 1 ×
At the belt position of 10 ¹² Ω · cm, r = log10 ¹²
/ Log (7 × 10 ¹³ ) ≈0.87, i = 0.9 from the straight line of FIG. 6, and I = i × I _N = 0.9 × 22
5≈203 μA. Similarly, R = 2 × 10 ¹⁵ Ω · c
At the belt position of m, I = 248 μA, and in the environment of 35 ° C. and 90%, (R, I) = (1 ×
10 ¹² , 68), (R, I) = (2 × 10 ¹⁵ , 83),
In an environment of 15 ° C. and 5%, (R, I) = (1 × 1
0 ¹² 270), (R, I) = (2 × 10 ¹⁵ , 330)
Therefore, if the control is performed in this manner in step S17, the optimum transfer current is applied.

By the way, as described above, it is suitable that the recording material carrying belt 8 has a high resistivity of 10 ¹² to 10 ¹⁵ Ω · cm. As previously proposed, it was difficult to control this in real time while measuring it onboard. This is because the measurement of a high resistance value involves the measurement of a minute current, so that noise is very likely to enter and highly accurate measurement is required. To achieve this, the cost is greatly increased due to the control. Therefore, as in the present embodiment, these problems are solved by measuring outside the machine and inputting the data into a non-volatile memory such as a ROM.

In the present embodiment, a recording material carrying belt having a joint is used as an intervening medium between the recording material 6 and the transfer energy applying means at the time of transfer, but the position of the intervening medium is described. Since it suffices to associate the position of the ROM data with the position of the ROM data, the seamless belt-shaped recording material holding means or the drum-shaped recording material holding means are within the scope of the present invention. is there. However, in the manufacturing process, the seamless belt shape has the most difficulty in the technique of homogenizing the physical properties, and is particularly effective when using such a recording material carrying means. further,
In this embodiment, a charger using corona discharge was used as the transfer energy applying means, but the present invention is not limited to this, and a roller type or contact type applying means such as a blade or a brush may be used. Needless to say.

In the above fourth embodiment, the standard transfer current determined by the environment of the apparatus is controlled by the ROM data which is the physical property value of the belt measured outside the machine to obtain the optimum transfer current value. However, it may be better to change the optimum transfer current value not only for the environment but also for other usage conditions and operating conditions in the apparatus.

Next, a fifth embodiment of the present invention will be described, which is included in the control requirements even when the recording material carrying belt is not sufficiently discharged, such as during continuous output or when the belt cleaning device 9 charges the belt.

FIG. 8 is a flow chart showing the sequence of the control operation of the fifth embodiment of the present invention. In this embodiment as well, the volume of the recording material carrying belt 8 before being mounted on the color copying machine shown in FIG. Since the operation of measuring the resistivity and inputting it to the ROM and determining the standard applied current at the time of transfer by the signal of the temperature and humidity sensor in the apparatus is the same as in the fourth embodiment, steps S11 to S16 will be performed. Will not be explained. In the flowchart of FIG. 8 as well, steps indicated by dotted lines indicate operations outside the machine, and steps indicated by solid lines indicate operations inside the machine.

In order to control the transfer current by the charge amount of the recording material carrying belt 8 during continuous output, after the belt cleaning device 9 and before the recording material 6 is fed,
There is a method of monitoring the surface potential of the carrier belt 8 with a potential sensor. Also in the case of the surface potential, as described above, it is very difficult to control in real time in the aircraft. Therefore, before the image formation, for example, before the fixing roller of the fixing device 7 reaches a predetermined temperature, or during the preparation time such as the time for monitoring the potential on the photosensitive drum before the latent image formation, the recording material The carrying belt 8 is pre-rotated, and the relative charge amount V of the belt is detected by the average value for one round of the belt at that time (step S18). Then, as shown in FIG. 5, when the belt charge amount V is V = + V ₁ , the control amount is 1.05 times the control amount described in the fourth embodiment. That is, when the surface of the recording material carrying belt 8 is negatively charged, an appropriate transfer current flows in the direction of the photoconductor drum unless a large amount of transfer current is applied from the back side of the carrying belt 8. Absent.

In this way, the ROM data read by the controller of the apparatus in the previous step S14 is corrected in step S19. In this way, data is obtained in which the volume resistivity of the recording material carrying belt 8 measured outside the machine and the electrostatic charge amount of the bell 8 measured after the carrying belt 8 is incorporated in the copying machine are included in the control requirements. In accordance with this data, in step S20, if the standard applied current determined by the environment in the apparatus is controlled for each belt position, the optimum transfer current can be applied to the transfer charger of the transfer unit.

Of course, the same control can be performed by monitoring the adsorption current and the transfer current in addition to monitoring the surface potential.

In the fourth and fifth embodiments, the case where only one table for converting the belt resistance ratio r into the transfer current ratio i is provided has been described. Generally, depending on the environment in which the device is placed, the hygroscopicity (water absorption) of the low resistance part and high resistance part of the carrier belt does not change so much and one straight line (conversion table) is sufficient for engineering plastics. Then many. However, when there is extreme unevenness during mixing or when the coating material is extremely uneven, it is possible to perform more preferable control by providing two or three conversion tables as shown in FIG. 6, depending on the environment. is there. Further, in the fourth and fifth embodiments, the control is based on the electrical characteristics such as surface potential and volume resistivity.
In addition to this, as described above, it is possible to perform control with the electric current such as the adsorption current and the transfer current, and further the electric characteristics such as the surface resistivity and the dielectric constant as parameters. The characteristics (physical properties) can also be controlled as parameters. Next, a case where the thickness of the recording material carrying belt 8 is controlled as a parameter will be described.

For example, when the carrier belt 8 is made of a polycarbonate resin in which a conductive material such as carbon is dispersed, the thick portion of the belt has a low resistance value and the thin portion has a high resistance value. It tends to be resistance. Further, with polyvinylidene fluoride (PVdF) or the like, a thick portion of the belt has a high resistance and a thin portion has a low resistance. As described above, although the characteristics differ depending on the material and the manufacturing method, the thickness at each position of the belt is associated with the resistance value of the belt with respect to such variations, and the optimum conversion is performed as shown in FIG. The transfer current can be determined.

Therefore, in an environment where the temperature is 25 ° C. and the humidity is 60%, the linear conversion table of FIG.
In an environment with a humidity of 90%, the low resistance part improves water absorption,
Water absorption is poor in the high resistance part, so like a straight line,
Since the resistance is further reduced in the low resistance portion, the transfer current is reduced below the standard applied current, and conversely, the transfer current is applied in the high resistance portion slightly larger than the standard applied current. Here, since the standard current is set to be 1.0 in any environment at the belt resistance ratio r = 1.0, it is always 1.0.

Further, it goes without saying that instead of the control for setting the standard applied current according to the environment, a control method for selecting the conversion table according to the environment as shown by the straight line in FIG. 6 may be used.

As described above, if the transfer current can be controlled by measuring the physical property values which are relatively easy to measure, such as the belt thickness measurement, the cost can be reduced especially when the recording material carrying belt 8 is mass-produced. It can have a great effect.

Further, it is very difficult to measure the thickness of the belt accurately during the normal image forming sequence,
A data measurement mode is provided in the operation sequence, and at the time of measuring the thickness of the belt, the belt portion sufficiently cleaned by the cleaning device is sequentially stopped, and the data can be acquired at arbitrary measurement intervals. As described above, parameters that are not suitable or impossible for real-time control can be used in the present invention.

Although the control of the transfer current has been described in the fourth and fifth embodiments, the control of the transfer voltage is not limited to the current control such as controlling the transfer voltage in the voltage control. Further, the type of recording material (recording medium) (for example, 80
It is known to control the transfer conditions by means of g paper and OHP film, etc., but the standard transfer current value I _N can be determined according to the kind of the recording material.
In this case as well, the same control as in the above-described fourth and fifth embodiments can be performed, and this is not described in detail, but is within the scope of the present invention.

As in the second, third and fifth embodiments,
In addition to the volume resistivity at positions at predetermined intervals in the moving direction of the recording material carrying belt 8, when the surface potential of the recording material carrying belt 8 is also included in the control requirements, the color copying machine shown in FIG. In, a potential sensor for measuring the surface potential of the recording material carrying belt 8 is required. As described above, it is desirable that the potential sensor is installed at a position between the belt cleaning device 9 and the recording material 6 being fed. This is because the recording material carrying belt 8 may be charged by friction with the brush or blade in the belt cleaning device 9. In the color copying machine having the configuration shown in FIG. 4, the above position was closest to the belt potential when the recording material was transferred. This is almost the same as the potential measured at the position of the photoconductor drum 1a of the first image forming portion Pa in this example, though it varies depending on the device.

[0074] Also, when using a corotron charger to the transfer charger of the transfer portion 4a~4d in a color copying machine of FIG. 4, with respect to the total current I ₀ which is applied to the corotron charger, a photosensitive drum 1a~ If I is the current in the 1d direction (which actually affects the transfer) and I'is the current flowing in the shield plate direction of the corotron charger, it can be regarded as I = I ₀ −I ′.

In the state where this expression is satisfied, the transfer current I ₀ calculated by the data of the RAM is carried with respect to the average value of the surface potential of the recording material carrying belt 8 as described in the first embodiment. Increase or decrease by one belt. This correspondence as shown in FIG. 5, the belt charging amount V is the 1.05I ₀ in the case of -V _1, when belt charging amount V of + V ₁ to 0.95I _0. As described above, when the surface of the recording material carrying belt 8 is charged due to poor charge removal or the like, an appropriate current I cannot be obtained unless the transfer current I ₀ is applied correspondingly. This leads to an increase in the transfer current I ₀ during multicolor and multiple transfer.

Generally, the surface potential of the recording material carrying belt is not suitable as a parameter for real-time control because it has many noises and fluctuations. However, by using the average value of several rotations as the parameter as in the above embodiment. , Has solved this problem. Furthermore, by adding the potential of the recording material carrying belt 8 as a parameter, a more appropriate transfer current I ₀ can be applied to each belt position.

When the transfer current is applied according to the belt charge amount, the applied transfer current is increased when the residual charge on the belt is large. If such a state continues, the residual charge on the recording material supporting belt 8 increases, causing a separation failure of the recording material, causing a jam, a cleaning failure that does not remove stains on the supporting belt, and further carrying The belt itself sticks to the surrounding side plates, resulting in various inconveniences such as a decrease in rotation speed and no rotation.

FIG. 9 is a characteristic diagram for explaining the control operation of the sixth embodiment of the present invention. In order to prevent the above-mentioned inconvenience, the charge removing condition of the recording material carrying belt 8 is controlled. It was done.

FIG. 9 shows a case in which only the DC component of current is controlled when a current (voltage) for eliminating static electricity, which is a superposition of direct current (DC) and alternating current (AC), is applied to the recording material carrying belt 8 from the static elimination means. The change in the surface potential on the recording material carrying belt 8 is shown. As is clear from the characteristics of FIG. 9, by changing the charge removal condition of the DC component according to the belt charge amount, it is possible to prevent the carrying belt 8 from being charged and reduce the control amount of the transfer condition.

In the case of this embodiment, the recording material carrying belt 8
Data of the surface potential is stored, and the (average) calculated value controls the transfer current according to other real-time signals such as an environmental signal. This is for controlling the transfer current and simultaneously controlling the charge elimination condition for variations in the physical properties of the recording material carrying belt 8 during one round. In the case of such control, since the stored parameter is the belt surface potential for one round, there is an advantage that the cost can be reduced.

However, since there is a difference in surface potential between the case where paper or the like is carried on the recording material carrying belt 8 and the case where it is not carried, the end portion of the recording material is carried no matter how the charge is removed. Some peaks of surface potential may remain at the belt position. In such a case, it may be necessary to perform processing such as excluding the peak value when calculating the average value. However, even in such a case, when it comes to fine adjustment of the transfer current, the transfer current is controlled by the variation of the resistance value of the recording material carrying belt 8 which is a direct parameter for adjusting the transfer current, and the charge removal is performed. It is more desirable to control the condition by the (average) calculated value of the surface potential. Therefore, this case will be described below. The operation of controlling the transfer current by the variation of the resistance value of the recording material carrying belt 8 which is a direct parameter for adjusting the transfer current is the same as that in each of the above-mentioned embodiments, and has already been described in detail. Therefore, the description thereof is omitted here.

When the resistance value of the recording material carrying belt 8 varies, the amount of charge remaining on this belt also changes. Therefore, by effectively controlling the DC current, it is possible to make the potential unevenness existing during one rotation of the recording material carrying belt 8 uniform.

For example, the characteristic curve shown by the solid line in FIG. 10 is about 3 KV, 200 μ when the carrying belt 8 is sufficiently destaticized.
The result of having measured the belt surface potential when the transfer high voltage of A is applied is shown. On the other hand, if the average value of the belt surface potential for one round is supposed to be 250V but is 500V, the belt is charged 250V more. Therefore, as shown in FIG. 9, by applying a static elimination current (characteristic curve shown by a broken line in FIG. 10) value in which the DC component is increased by 150 μA, the uneven potential of the belt is effectively removed and the surface potential is made uniform. can do.

The present invention can be made more efficient by combining it with various signals. For example, output image signal value, output operation and output operation preparation, recording material type,
The output number setting value and the like.

First, in the case of the output image signal value, the output color has the most influence. When there are four image carrier colors that do not affect the image output (for example, when the image carrier colors are four colors of cyan (C), magenta (M), yellow (Y), and black (BK),
In the case of a black monochromatic image, cyan, magenta, and yellow do not affect the image output.) When the transfer electric energy is not applied, the surface potential on the recording material carrying means also changes. In such a case, if the transfer voltage is applied to all the image carriers and if the same DC component is used for the charge removal, it will be excessively applied and the recording material carrying means will be charged to the opposite potential. Sometimes. Therefore, in such a case, it is necessary to control according to each output mode and adjust the applied voltage.

Next, in the output operation and the output operation preparation, the transfer voltage is not applied or not applied in the output operation preparation, so that it is almost unnecessary to apply the DC component. At the time of output operation, for at least one image carrier,
Since the transfer current is applied, it is necessary to remove the charge, and an effective method is to apply the AC and DC components. In addition to the above-mentioned parameters, the applied amount depends on the film that is often used as the recording material such as OHP, general PPC paper, thick paper of 100 g / m ² or more, thin paper of 60 g / m ² or less, and the like. Control according to the potential change at such a recording material edge position is effective.

Further, when the number of output sheets is one and when the number of output sheets is a plurality of sheets, the amount of electric charge applied on one circumference of the belt and the timing are different. In the latter case, it is applied almost continuously, whereas
In the former case, the conditions change such that only one sheet is applied.

By controlling according to various situations as described above, the characteristics of the recording material carrying belt are measured outside the apparatus and stored in the ROM, as in the fourth and fifth embodiments.
When controlling the static elimination conditions as in the sixth embodiment, effective static elimination can be performed without constantly measuring the potential on the surface of the recording material carrying belt.

In order to measure the potential of the surface of the recording material holding means in real time, it is considerably affected by toner stains on the recording material hold means, toner stains of the potential sensor, etc., and an appropriate value can be obtained due to variations in the thrust direction. There is a problem such as not. In other words, the optimum static elimination is originally 100-150μ.
The position where the DC of A should be applied is measured so that it may be applied around 150 μA depending on the sensor position. As a result, there is a problem that a slightly larger amount of voltage is applied and an excessive amount is applied. In order to solve this, it is necessary to provide a plurality of potential sensors in the thrust direction. Considering such errors and costs, it is effective to use a method in which the potential sensor is not provided and the resistance value (rate) unevenness of the recording material holding means, the environment, and other parameters described above are used for control. It falls within the range.

Next, a seventh embodiment of the present invention will be described. In this embodiment, a conductive brush having a plurality of brush electrodes provided in the main scanning direction is used as the transfer portions 4a to 4d of the color copying machine of FIG.
Is used as the transfer charging means of the above, and therefore, unlike the transfer chargers of the above-described first to sixth embodiments,
In this embodiment, electric energy for transfer is applied in a state where the conductive brush is in contact with the back surface of the recording material carrying belt 8 (the surface on which the recording material 6 is not carried). An example of this conductive brush is shown in FIG. FIG. 12 shows the structure of the brush thread used for each brush electrode.

As shown in FIG. 12, each of the N brush electrodes 101, 102, ..., 10N constituting the conductive brush of FIG. 11 has a conductive member 30 in which carbon is dispersed in a rayon material. The outer periphery of the is coated with an insulating resin 31, and the electrical conductivity is anisotropic. Each brush electrode 101, 1 of the conductive brush of FIG.
Reference numerals 02, ..., 10N are bundles of the brush threads shown in FIG. 12 and are formed into a substantially cylindrical shape.
50 μm PET (polyethylene terephthalate resin)
Are arranged. Here, in this embodiment, the volume resistivity of the conductive member 30 of the brush thread shown in FIG. 12 is about 10 ⁵ Ω.
cm, and that of the insulating resin 31 was set to about 10 ¹⁸ Ω · cm.

In the color copying machine having the structure shown in FIG. 4, if the volume resistivity of the recording material carrying belt 8 is uneven,
Even when the same transfer voltage is applied, the flowing current varies depending on the place. When the recording material carrying belt 8 as described above is manufactured by extrusion molding or the like, even if the resistance value unevenness in the pull-out direction is suppressed, it is very difficult to suppress the variation in the resistance value in the direction perpendicular thereto. However, the longer the belt, the more difficult it becomes to suppress the degree of variation. This is because the manufacturing method tends to cause variations in thickness, electric resistance, and composition in the latter direction. In this way, the recording material carrying belt 8 is formed by endlessly connecting the films having the variations in the electric resistance characteristics.
When used as, the direction having variations cannot be used as the main scanning direction in the past. Further, even if the variation of the electric resistance is controlled in the sub-scanning direction, the belt having the variation on the main scanning side cannot be used.

The present embodiment solves such a problem and makes it possible to obtain a stable image having a uniform density even if the recording material carrying belt 8 varies as described above.

The unevenness of the electric resistance value due to the uneven mixing of the recording material carrying belt 8 does not need to be controlled in a very narrow region.
In this embodiment, 29, which corresponds to the length in the longitudinal direction of A4 size,
5 divisions (5 brush electrodes 10) for a transfer width of 7 mm
1 to 105) was used, a sufficiently uniform and stable image could be obtained. The variation in resistance of the recording material carrying belt 8 at this time was 10 ¹³ to 10 ¹⁵ Ω · cm, and the applied voltage was controlled to 1.6 KV to 1.8 KV.

In this embodiment, in order to perform more effective control, the electroconductivity of the electroconductive brush is made anisotropic, and in particular, the main scanning direction (transverse direction) of the electroconductive brush is set.
It is preferable that the conductivity is equal to or slightly higher than the resistance value of the recording material carrying belt 8. That is, if it is too low, the control effect is lowered, and if it is too high, fine streak-like density unevenness occurs on the image, or the applied voltage must be increased.

In general, the variation in the resistance value as described above is not likely to cause a rapid unevenness of the mixing ratio, so that the variation is large in many cases. On the other hand, it is possible to cope with the change by performing fine control.
In the case of the configuration as shown in FIG. 1, even if the applied voltages to the adjacent brush electrodes are made different from each other, there is a leakage current between the adjacent brush electrodes, so that the change never occurs rapidly. The voltage gradient between the adjacent electrodes can be changed by the brush thread coating member 31 shown in FIG. 12, and can be adapted according to the material of the recording material carrying belt 8.

In the seventh embodiment, a plurality of brush electrodes formed into a substantially cylindrical shape by a large number of brush threads are used.
Although the outer peripheral surfaces of the conductive brushes are brought into contact with each other and the conductive brushes arranged in a line in the main scanning direction are used as the transfer charging means, the structure of the conductive brush is not limited to that shown in FIG. For example, as shown in FIG. 13, a plurality of brush electrodes 2 in which brush threads as shown in FIG. 12 are radially implanted on the outer peripheral surface of a cylindrical member, respectively.
0M, 20 (M + 1), 20 (M + 2), ... Are arranged in the main scanning direction so that their axes are aligned with each other by using a conductive brush of a roller structure or other structure. Needless to say, the conductive brush of No. 1 may be used.

FIG. 12 shows the structure of the brush thread which constitutes the conductive brush. In the present invention, the conductive member 30 is used.
It is not indispensable to coat the insulating resin 31 with the insulating resin 31. For example, when the brush thread (wire material) 30 is manufactured by mixing the substance A having good conductivity and the substance B having insulating property, the mixing ratio of the substance A to the substance B is increased only in the central portion, or is formed into a sandwich shape. It is also possible to use a material having good conductivity in the central portion and a high resistance material on the outside. Further, instead of insulating each brush thread (wire material) one by one, it is also possible to partition each brush electrode with an insulating material or a high resistance material. That is, the brush threads constituting the brush electrodes 101, 102, ... Are not insulated from each other as shown in FIG. 11, but each brush thread 30 is not coated with an insulating coating as shown in FIG. Instead, a conductive brush having a structure in which the PET film 33 is interposed between the brush electrodes may be used. The potential difference gradient between the brush electrodes at this time can be controlled by the resistance value (thickness, size, composition, etc.) of the PET film 33.

Further, although the conductive brush is used as the transfer charging means in the above embodiment, the transfer charging means is not limited to the brush. For example, it may have a shape as shown in FIG. 13 in which a plurality of conductive resin rollers (of course, brush threads are not used) and the like are arranged so as to form a straight line in the roller axial direction. In this case, the resistance in the axial direction of the roller may be increased and the inductance in the direction of the transfer current may be set lower than the resistance in the axial direction. That is, in the case of a conductive resin roller, the conductive resin layer is thinned so that the resistance value in the thickness direction of the recording material carrying belt is lower than the resistance of the conductive resin layer, whereby the transfer current is reduced. (Voltage) can be controlled. As described above, when one electrode is used as one block, it is possible to control by providing anisotropy between the conductivity between blocks and the conductivity in the transfer electric field application direction, and the conductivity is not necessarily ensured within each block. It is not necessary to have anisotropy, and technical steps such as coating are not always necessary.

In the above embodiment, the case where the present invention is applied to an electrophotographic color copying machine having a plurality of image bearing members and using a recording material bearing means in which endless belts are joined together will be described. However, the present invention is not limited to this, and the electrophotographic color or color of various other configurations such as using a drum-shaped recording material carrying means or having one image carrier is provided. It is equally applicable to a monochromatic (black and white) image forming apparatus and an electrostatic recording type image forming apparatus. Further, it goes without saying that the control system, the control mode, etc. are not limited to those of the embodiment.

[0101]

As described above, according to the present invention,
The physical property value of the medium, which is interposed between the recording material and the energy applying unit that contributes to the transfer at the time of transfer, is measured in the image forming apparatus, and the data is stored in a storage unit such as a RAM and based on the stored data. Since the transfer energy is controlled by using the
The transfer energy can be controlled by the data that suppresses the influence of dirt and the like, and there is an effect that a good image with a uniform density can be obtained even if a recording material carrying means having a variation in physical property value is used. . In addition, since the recording material holding means having the different physical property values can be used, there is an effect that the manufacturing efficiency is improved and the cost can be reduced. Furthermore, by carrying out this control periodically in the apparatus, it is possible to control the transfer energy that follows deterioration and changes of the device parts, members, elements, etc., so that good images with uniform density can be obtained at all times. There is an effect that can be obtained.

Further, according to the present invention, the physical property value of the medium interposed between the recording material and the energy applying means contributing to the transfer at the time of transfer is measured outside the image forming apparatus, and the data is stored in a nonvolatile memory such as a ROM. The transfer energy is stored in the property storage means, and the transfer energy is controlled on the basis of the data stored in the apparatus. Therefore, ideal transfer energy can be always applied, and recording with variations in physical property values can be performed. Even when using a material carrying means, it is possible to suppress image unevenness after transfer,
There is an effect that a good image having a uniform density can always be obtained. In addition, since the recording material holding means having the different physical property values can be used, there is an effect that the manufacturing efficiency is improved and the cost can be reduced.

Further, according to the present invention, the physical property value relating to the surface potential of the recording material carrying means is stored in the storage means such as RAM or ROM, and based on the stored data, a good transfer current (voltage ) Is applied so that the recording material holding means is prevented from being defective in static elimination, so that the charging failure due to the variation in the resistance value of the recording material holding means is eliminated, and the recording material holding means having the variation in the physical property value is eliminated. Even if is used, there is an effect that a good image having a uniform density can be obtained. In addition, there is an effect that an image having a good uniform density can be obtained without expanding the control range of the transfer current (voltage).

Furthermore, according to the present invention, the transfer charging means such as a conductive brush or a conductive roller having a plurality of electrodes provided in the main scanning direction is used to control the transfer energy applied in the arrangement direction of these electrodes. Therefore, there is an effect that unevenness appearing on the image at the time of transfer can be made uniform, and an excellent image having uniform density can be obtained. Further, along with this, it is possible to use the recording material carrying means having uneven resistance value, so that there is an effect that the manufacturing efficiency is improved and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a flowchart showing an operation sequence of a first embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a current applied to a transfer charger and a current flowing toward a photosensitive drum or toward a shield plate of the transfer charger.

FIG. 3 is a characteristic diagram showing a relationship between a transfer current ratio and a logarithm (logR) of a resistance value of a recording material carrying belt.

FIG. 4 is a schematic configuration diagram showing an example of an electrophotographic color copying machine to which the present invention can be applied.

FIG. 5 is a characteristic diagram showing a relationship between a transfer current ratio and a belt charge amount for explaining a control operation of the second embodiment of the present invention.

FIG. 6 is a characteristic diagram showing a relationship between a transfer current ratio and a belt resistance ratio for explaining a control operation of a third embodiment of the present invention.

FIG. 7 is a flowchart showing an operation sequence of a fourth embodiment of the image forming apparatus according to the present invention.

FIG. 8 is a flowchart showing an operation sequence of a fifth embodiment of the image forming apparatus according to the present invention.

FIG. 9 is a characteristic diagram showing changes in the surface potential of the recording material carrying belt for explaining the control operation of the sixth embodiment of the present invention.

FIG. 10 is a characteristic diagram showing an example of a charge eliminating state of a recording material carrying belt.

FIG. 11 is a schematic perspective view showing an example of a conductive brush used in a seventh embodiment of the present invention.

FIG. 12 is a schematic perspective view showing the configuration of brush yarns that form the conductive brush of FIG.

FIG. 13 is a partially cutaway schematic perspective view showing another configuration of the conductive brush that can be used in the present invention.

FIG. 14 is a schematic perspective view showing still another configuration of the conductive brush that can be used in the present invention.

[Explanation of symbols]

 Pa to Pd image forming unit 1a to 1d photoconductor drums 2a to 2d latent image forming unit 3a to 3d developing unit 4a to 4d transfer unit 5a to 5d cleaning unit 6 recording material 7 fixing device 8 recording material carrying belt 9 belt cleaning device 13 Registration roller pair 30 Conductive member 31 Insulating resin 32 Backup member 33 PET film 60 Recording material cassette 10N, 20N Brush electrode

Claims (13)

[Claims] 1. An image carrier, a recording material carrying means for carrying a recording material onto which a visible image formed on the image carrier is transferred, and conveying the recording material to a transfer position of the image carrier, and the transfer. An image forming apparatus comprising: an energy applying unit that applies energy contributing to transfer via the recording material supporting unit to the recording material at a position to transfer a visible image on the image carrier to the recording material, The physical properties that contribute to the transfer of the recording material carrying means are measured in the image forming apparatus, and the measured values are stored in correspondence with the measurement positions of the recording material carrying means, and the stored measured values at the time of image formation. Based on the above, the image forming apparatus is characterized in that the transfer condition is controlled by the position of the recording material carrying means. 2. The physical properties contributing to the transfer of the recording material holding means include electrical characteristics such as volume resistivity, surface resistance, and dielectric constant of the recording material holding means, and the thickness and surface property of the recording material holding means. The image forming apparatus according to claim 1, wherein the image forming apparatus has mechanical characteristics such as 3. The image forming apparatus according to claim 1, wherein the measurement result of the physical properties of the recording material carrying unit is corrected or controlled by another signal in the image forming apparatus. 4. The other signals in the image forming apparatus are the environment such as temperature and humidity, the type of recording material, the electrical characteristics or the mechanical characteristics of the recording material holding means in the image forming apparatus. The image forming apparatus according to claim 3, which is characterized in that. 5. An image carrier, a recording material carrier that carries a recording material on which a visible image formed on the image carrier is transferred, and conveys the recording material to a transfer position of the image carrier, and the transfer. An image forming apparatus comprising: an energy applying unit that applies energy contributing to transfer via the recording material supporting unit to the recording material at a position to transfer a visible image on the image carrier to the recording material, The physical properties that contribute to the transfer of the recording material carrying means are measured outside the image forming apparatus, and the measured values are stored in the non-volatile storage means corresponding to the measurement position of the recording material carrying means. An image forming apparatus characterized in that a transfer condition is controlled by a position of the recording material holding means based on a measured value stored in a storage means. 6. The physical properties that contribute to the transfer of the recording material holding means include electrical characteristics such as volume resistivity, surface resistance, and dielectric constant of the recording material holding means, and the thickness and surface property of the recording material holding means. The image forming apparatus according to claim 5, wherein the image forming apparatus has mechanical characteristics such as. 7. The image forming apparatus according to claim 5, wherein the measurement result of the physical properties of the recording material carrying unit is corrected or controlled by another signal in the image forming apparatus. 8. The other signal in the image forming apparatus is an environment such as temperature and humidity, a type of recording material, an electric characteristic or a mechanical characteristic of a recording material holding means in the image forming apparatus. The image forming apparatus according to claim 7, which is characterized in that. 9. An image carrier, a recording material carrying means for carrying a recording material onto which a visible image formed on the image carrier is transferred, and conveying the recording material to a transfer position of the image carrier, and the transfer. An image forming apparatus comprising: an energy applying unit that applies energy contributing to transfer via the recording material supporting unit to the recording material at a position to transfer a visible image on the image carrier to the recording material, An image forming apparatus, which stores a physical property value that contributes to transfer of the recording material carrying means, and controls a charge eliminating condition of the recording material carrying means based on the stored data. 10. The static elimination means for eliminating static electricity from the recording material carrying means is a charging means for applying static elimination energy by superimposing direct current and alternating current, and the controlled static elimination condition is a direct current component of the static elimination energy. The image forming apparatus according to claim 9, wherein the image forming apparatus is an image forming apparatus. 11. A means for measuring a surface potential on the recording material carrying means, the result of the surface potential measurement being compared with stored data relating to the recording material carrying means for controlling transfer conditions. 10. The image forming apparatus according to claim 9, wherein at least one of the charge removal and separation of the recording material and the recording material carrying means, and the peeling condition is controlled. 12. An image carrier, a recording material carrier that carries a recording material on which a visible image formed on the image carrier is transferred, and conveys the recording material to a transfer position of the image carrier, and the transfer. An image forming apparatus comprising: an energy applying unit that applies energy contributing to transfer to the recording material through the recording material supporting unit at a position to transfer a visible image on the image carrier to the recording material, An image forming apparatus, wherein the energy applying unit has a configuration in which a plurality of electrodes are arranged in a direction perpendicular to a recording material conveyance direction, and controls transfer energy applied in a direction in which the electrodes are arranged. 13. The image forming apparatus according to claim 12, wherein the transfer energy is a transfer electric field, and the transfer electric field is controlled at least with respect to the electric conductivity of the recording material carrying means.