JPH05313515A - Multicolor image forming device - Google Patents

Abstract

PURPOSE:To provide the multicolor image forming device capable of always forming an appropriate transfer electric field when a toner image is transferred in any transferring order under various environment of use. CONSTITUTION:A temperature/humidity sensor 505 detecting the temperature and/or humidity inside the device and outputting voltage signal corresponding to the detected temperature/humidity is provided and the detection output is fed to CPU510 after being converted to a digital signal. First, judgement is made by the CPU510 of which environmental range set to a table 1 the detected output belongs to by referring to the table 1 integrated to a memory 511, and following that, the transfer current value data and destaticizing voltage control condition, etc., corresponding to the type of toner (electrified charge quantity of the toner) of the transferred toner image are read by taking into reference a table 2 integrated to the memory 511. Thus, the transfer current value and the destaticizing voltage control condition where the best transfer efficiency is shown are selected and the transfer electric field is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to electrophotographic, electrostatic recording, etc. image forming apparatus, but is not limited to a multicolor electrophotographic copying apparatus having a plurality of developing devices. Firstly, the present invention relates to a multicolor image forming apparatus which can be suitably embodied in various color copying machines such as recording apparatuses and color printers which constitute an output unit of a facsimile or a computer. Of course, the image forming apparatus of the present invention is not limited to this as described above.

[0002]

2. Description of the Related Art Hitherto, various multicolor electrophotographic copying apparatuses have been proposed and put to practical use. FIG. 2 shows a schematic configuration of an example of a multicolor electrophotographic copying machine equipped with a developing device which is a typical so-called rotary developing device.

To briefly explain with reference to FIG. 2, a multicolor electrophotographic copying apparatus of this type is rotatably supported by a shaft, rotates in the direction of the arrow in the drawing, and an electrostatic latent image is formed on the outer peripheral surface thereof. Image carrier, that is, the photosensitive drum 1, and the image forming means is arranged on the outer peripheral portion thereof. This image forming means may be any means, but in this example, a primary charger (corona charger) 2 for uniformly charging the photosensitive drum 1;
An image exposure system 3 including, for example, a laser beam exposure device, which irradiates a color-separated optical image or an optical image corresponding to the image to form an electrostatic latent image on the photosensitive drum 1, and the photosensitive drum 1.
And a rotary developing device 4 for converting the above electrostatic latent image into a visible image.

This rotary developing device 4 includes, for example, four developing devices 4Y and 4M which respectively store four color developers, that is, a yellow color developer, a magenta color developer, a cyan color developer and a black color developer. 4C, 4BK and these four developing devices 4
It comprises a substantially cylindrical housing 4a which holds Y, 4M, 4C and 4BK and is rotatably supported by a shaft 4b. The rotary developing device 4 conveys a desired developing device to a position facing the outer peripheral surface of the photosensitive drum 1 by the rotation of the housing 4a, develops the electrostatic latent image on the photosensitive drum 1, and the housing 4a By rotating, so-called full-color development for four colors can be performed.

A visible image, that is, a toner image on the photosensitive drum 1 is transferred to a transfer material which is carried and carried by a transfer material carrier of transfer means. In this example, the transfer material carrier is a transfer drum 5 that is rotatably supported, and the transfer drum 5 is positioned in the rotation direction of the photosensitive drum 1 and is in contact with the surface of the photosensitive drum 1. Or, it faces the photoconductor drum 1 in a slightly separated state. This transfer drum 5
Is equipped with a cylinder 5a, a transfer charger 5b which constitutes a transfer means together with the transfer drum 5, a transfer material gripper 5c, an inner charger 5d, and an outer charger 5e.
As shown in FIG. 3, a transfer material carrying sheet 501 such as a dielectric sheet (for example, PET (polyethylene terephthalate) film) is stretched over the outer peripheral surface opening of the sheet.

The toner remaining on the photosensitive drum 1 without being transferred to the transfer material is scraped and collected by the cleaner 6. Further, in the multicolor electrophotographic copying apparatus shown in FIG. 2, two removable transfer material cassettes 7a and 7b containing transfer materials of different sizes are attached to the lower right side of the drawing. In the upper right part of the figure, a discharge tray 10 for receiving the transfer material that has been fixed and discharged to the outside of the apparatus.
Is detachably attached.

Next, a process of forming a full-color image by the multicolor electrophotographic copying apparatus having the above-mentioned structure will be briefly described. First, the primary charger 2 and the image exposure system 3 are driven to form a blue color-separated electrostatic latent image on the outer peripheral surface of the photosensitive drum 1, and the electrostatic latent image is stored in the developing device 4Y. It is developed with a yellow developer. On the other hand, the transfer material fed from the transfer material cassette 7a or 7b to the transfer drum 5 by the transfer material conveying means 60 is gripped by the gripper 5c at the tip thereof and carried by the transfer drum 5, and the transfer drum 5 rotates. Along with this, the toner image formed on the outer peripheral surface of the photosensitive drum 1 is conveyed to a transfer area to which the toner image is transferred. The toner image is transferred onto the transfer material by the operation of the transfer charger 5b.

The above-mentioned image forming and transferring operations are performed by magenta,
Repeatedly for each color of cyan and black,
The operation of the transfer charger 5b is repeated until the transfer operation for the fourth color is completed. When the superimposing transfer of the four color visible images onto the transfer material is completed, the transfer material is neutralized by the inner charger 5d and the outer charger 5e of the transfer drum 5, and then the gripper 5c is released and the separation claw 8 is removed. When it is operated, it is separated from the transfer drum 5, sent to the fixing device (usually a heat roller fixing device) 9 through the conveying means 61, fixed, and discharged onto the paper discharge tray 10. on the other hand,
The residual toner on the photosensitive drum 1 is removed by the cleaner 6, and the next image forming process can be performed. The polarity of the transfer voltage supplied to the transfer charger 5b is set to be positive when the toner of each developer is negatively charged.

By the way, in the transfer process described above,
The transfer current is sequentially increased each time the visible image formed on the photosensitive drum 1 is repeatedly transferred to the transfer material by the developer of each color. This is due to the reason described below.

[0010] That is, first, when feeding an electric current I ₁ during the first performing transfer by the transfer current, the transfer material carrying sheet 501 as described above shown in FIG. 3 is charged V _1, the photosensitive drum 1 on The first visible image formed on the transfer material is transferred onto the transfer material. As described above, the transfer material is fixed on the transfer material holding sheet 501 by the transfer material gripper 5c, and the transfer drum 5 is rotationally moved at a rotational speed substantially equal to the rotational speed of the photosensitive drum 1. 1 is moved in synchronism with the rotation of the photosensitive drum 1, and the transfer material after the transfer of the visible image from the photosensitive drum 1 is carried out in the vicinity of the air when the photosensitive drum 1 is peeled off. Ionize. At this time, as described above, if the toner of each developer is charged to the negative polarity and the polarity of the transfer voltage is set to the positive polarity, the negative charge of the air ionized by the peeling of the transfer material is charged. Those attached to the transfer material are attached to the surface of the transfer material, and those attached to the positive charge are attached to the outer peripheral surface of the photosensitive drum 1. As a result, the negative charge attached on the transfer material affects the positive charge due to the transfer current existing on the back surface of the transfer material sheet 501, and acts as a whole to weaken the transfer electric field formed by the transfer current. On the other hand, since the toner itself that forms the visible image transferred from the outer peripheral surface of the photosensitive drum 1 to the transfer material is also negative, the transfer electric field is weakened as in the above phenomenon. Therefore, it is necessary to increase the transfer current supplied to the transfer charger 5b at the next transfer so as to compensate for the transfer electric field formed at the next transfer.

Here, the transfer current and the transfer material carrying sheet 50
As for the relationship with the charging potential of 1, when the polarity of the transfer voltage is set to plus as described above,
If the transfer current at the _second transfer is I ₂ , and the charging potential of the transfer material carrying sheet 501 by this transfer current is V ₂ , then I
₁ <I ₂ , V ₁ <V ₂ . Transfer material carrying sheet 501
It is desirable to establish a relationship of | V ₂ −V ₁ | ≧ 0.5 KV between the _second charging potential V ₂ and the first charging voltage V ₁ Even at times, it is preferable that the same relationship as above is established.

However, in the conventional multicolor electrophotographic copying apparatus having the above-described structure, the transfer material carrying sheet 501 is used.
On the other hand, the value of the transfer current supplied to the transfer charger 5b for applying the transfer electric field was adjusted so that the amount of change was always constant over a preset operating temperature range of the apparatus. Therefore, if the environment in which the device is installed changes to a high temperature and high humidity environment where the humidity is particularly high, the volume resistance of the transfer material used (especially when paper is used as the transfer material) is (For example, 23 ° C., 60%) Compared with the case under, it is reduced to about 1/100. At this time, the volume resistance of the transfer material carrying sheet 501 also decreases. Therefore, if a transfer is performed with the transfer current setting value as described above, a phenomenon of so-called transfer omission, which occurs when the transfer electric field is too strong, easily occurs.

Contrary to the above, when the environment in which the apparatus is installed changes to a low temperature and low humidity environment where the humidity is particularly low, the volume resistance of the transfer paper, which is the transfer material, is higher than that in the normal temperature and normal humidity environment. It rises to about 100 times. At this time, the volume resistance of the transfer material carrying sheet 501 also increases. Therefore, since the transfer current of the nth color is not discharged by an appropriate amount before the transfer of the (n + 1) th color, charges are sequentially accumulated, and if the transfer current setting value is left as it is, an image defect due to a decrease in transfer efficiency is likely to occur. was there.

Therefore, for the purpose of solving the above-mentioned problems, a humidity sensor is used to detect the humidity in the environment where the apparatus is installed, and the transfer current is set according to the detected humidity value. A method of changing the value has been proposed.
However, a humidity sensor such as a crystal humidity sensor, a polymer humidity sensor, or a ceramics humidity sensor that is generally used as a humidity sensor detects the relative humidity in the humidity environment in which the humidity sensor is installed and detects the relative humidity. Since it is configured to output an electric signal according to the humidity value, it is not possible to detect, for example, the amount of water in the atmosphere that causes the resistance value of the transfer paper to change.

Next, the reason for this will be described with reference to FIG. In FIG. 4, the amount of water contained in the atmosphere per unit volume (saturated water content) is calculated from the saturated water vapor pressure with respect to temperature with 30 ° C. as 100. For example, when the temperature of the measurement atmosphere is 30 ° C. and the moisture content in the atmosphere is 100, the humidity sensor outputs a voltage signal corresponding to 100% relative humidity, and when the moisture content is 50, the relative humidity is 50%. Will output a voltage signal corresponding to. Figure 4
According to the above, the saturated moisture content in the atmosphere is about 31 when the temperature of the measurement atmosphere is 10 ° C., but the temperature of the measurement atmosphere is 30.
Assuming that the moisture content is about 31 at the temperature of ° C, the humidity sensor outputs a voltage signal corresponding to a relative humidity of 31%.
At 0 ° C., the humidity sensor outputs a voltage signal corresponding to 100% relative humidity. Therefore, the correct amount of water in the atmosphere is not detected. Therefore, if the humidity sensor having such an output characteristic is used and the output signal is simply read and corrected, the volume resistance of the transfer paper and the surface resistance of the transfer material carrying sheet 501 depend on the amount of moisture in the atmosphere. Therefore, it is completely unsuitable for control for the purpose of increasing the set value of transfer current in a low humidity environment and decreasing the set value of transfer current in a high humidity environment. That is clear.

In view of the above points, in order to provide a device capable of preventing a phenomenon in which a transfer failure occurs due to a change in environment and always forming an image of good quality, temperature / humidity in the device. A sensor is provided to detect the temperature and / or humidity prior to the copying operation, and the set value of the transfer current supplied to the transfer charger 5b is adjusted based on the comparison result between the detected value and a preset reference value. And the inner charger 5 is adjusted according to the adjustment of the transfer current.
It is conceivable that the set value of the static elimination voltage supplied to the outer charger 5e and the like is also adjusted. However, as described above, if the moisture content of the environment in which the device is placed cannot be accurately detected, it is expected. Cannot achieve the purpose of.

On the other hand, in the multicolor image forming apparatus having the above structure, at least one type of toner used is 10 ¹² Ω.
-It has been proposed that the toner containing a substance having a volume resistivity of cm or less reduces the charge amount of the toner, improves transfer efficiency, reduces the capacity of the transfer power supply, and reduces the cost. ..

[0018]

However, in such a multicolor image forming apparatus, when the transfer current value is controlled according to the ambient environment of the apparatus as in the conventional example, 10
^The required transfer current value between the toner containing a substance having a volume resistivity of ¹² Ω · cm or less (eg black toner BK) and the toner not containing it (eg yellow toner Y, magenta toner M, cyan toner C) Since they differ greatly, it is necessary to give an appropriate transfer current value when transferring each toner image.

FIG. 5 shows two approximately equal moisture content curves D ₁ and D.
_The environment in which the equipment is installed by ₂ is the low temperature / low humidity area L
L, normal temperature / normal humidity region NN, and high temperature / high humidity region HH are shown separately. The area surrounded by the one-dot chain line in the figure is a range in which a normal color copying machine can properly operate. In each region, the charging characteristics of the toner, the charging characteristics of the transfer material, the moisture absorption and charging characteristics of the transfer material carrying sheet are almost the same, and it is considered that the environment is similar. Representative point A of each of these areas
(Temperature 20 ° C, Humidity 15%), B (Temperature 23 ° C, Humidity 6)
0%) and C (temperature 30 ° C., humidity 70%), and the above-described yellow Y, magenta M, cyan C, and black BK toner images of respective colors are superimposed and transferred onto a transfer material to form a full-color image. The optimum transfer current value at that time was as shown in Table 1 below. Note that materials in this case, the black developer using a toner containing a substance having the following volume resistivity of 10 ¹² Ω · cm, other color developer having a 10 ¹² Ω · cm or less in volume resistivity A normal toner containing no is used.

[0020]

[Table 1]

However, since the multi-color image forming apparatus having the above-mentioned structure can form not only full-color images but also multi-color or mono-color images, the order of image formation is not limited to the order shown in Table 1 above. Further, there is a case where an image of only a single color is formed. For example, when a black image is formed in a black single color mode in an environment of a temperature of 20 ° C. and a humidity of 15%, the set value of the transfer current for the first color is 150 μA. The toner image is transferred, and as a result, the transfer current value actually required to transfer the black toner image (200 μm in this example)
A large difference occurs between the case of A) and the image defect such as transfer omission. This phenomenon naturally occurs when the transfer order of toner images is changed or when a multi-color image is formed.

As described above, in the conventional control of the transfer current according to the ambient environment, the transfer current value greatly differs when transferring a single color image with toner having different charge amounts or when the transfer order of the toner images changes. This has been a cause of image defects such as transfer defects and image distortion.

Therefore, an object of the present invention is to always form an appropriate transfer electric field in any use environment and in any transfer order of a visible image (toner image), so that a good image quality can be obtained. It is an object of the present invention to provide a multicolor image forming apparatus which can always obtain a transferred image.

[0024]

The above object can be achieved by a multicolor image forming apparatus according to the present invention. In summary, the present invention provides an electrostatic latent image formed on the image carrier, having an image carrier, means for forming an electrostatic latent image on the image carrier, and plural kinds of toners. Developing means for forming a visible image by attaching toner to the image carrier, and transfer means for transferring the visible image formed on the image carrier to the transfer material held on the transfer material carrier by an electric field, In a multicolor image forming apparatus in which at least one kind of the toner has a charge amount of 15 μC / g or less, a temperature / humidity detecting unit for detecting temperature and / or humidity inside the apparatus, and an environment in which the apparatus is installed. Storage means for storing a plurality of sets of data relating to the transfer electric field in a variable range of temperature and / or humidity that is expected in the above. Data Is a multi-color image forming apparatus characterized by comprising.

[0025]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The following embodiment is a case where the present invention is applied to the above-described multicolor electrophotographic copying apparatus shown in FIG. 2, and therefore the overall configuration, operation and action are basically as described above. Therefore, these will not be described in detail.

FIG. 3 is an enlarged view of the transfer area and its vicinity of the multicolor electrophotographic copying apparatus according to the first embodiment of the present invention, which is similar to the multicolor electrophotographic copying apparatus shown in FIG. .. In FIG. 3, the transfer charger 5b has the opening width set to 22 mm and the distance between the discharge wire 504 and the outer peripheral surface of the photosensitive drum 1 set to 11 mm. The transfer material carrying sheet 501 stretched around the opening of the outer peripheral surface of the cylinder 5a of the transfer drum 5 forms a cylinder having a diameter of 160 mm, and its moving speed is set to 160 mm / sec. Temperature / humidity detecting means for detecting the temperature and / or humidity of the environment in which the device is placed, that is, the temperature / humidity sensor 505 is in the vicinity of the transfer material carrying sheet 501 and at a position that does not hinder the rotational movement of the transfer drum 5, For example, as shown in the figure, it is provided inside the transfer material carrying sheet 501 upstream of the transfer area. The temperature / humidity sensor 505 detects the temperature and / or humidity inside the apparatus and outputs a voltage signal according to the detected temperature / humidity.

FIG. 1 shows a control system according to the first embodiment of the present invention. In FIG. 1, the temperature / humidity sensor 505 outputs a temperature detection signal (hereinafter referred to as “T signal”) and / or a humidity detection signal (hereinafter referred to as “H signal”), and the T signal is the first signal.
Of the analog-to-digital converter (A / D) 506, and the H signal is sent to the second A / D 515.
The first A / D converts the T signal into a digital signal and
To the I / O (input / output) port 508 of the second A /
D515 converts the H signal into a digital signal and outputs the second I signal.
Supply to the / O port 507. The CPU 510 has the I / O function prior to a series of image forming operations by the copying apparatus.
Read each signal input to the ports 507 and 508,
Area designation of which area of the areas LL, NN, and HH set in the table 1 belongs to by referring to the table 1 (detailed in FIG. 5) built in the memory 511 Do. After specifying the area, CP
U510 refers to the table 2 stored in the memory 511, and based on the table, the transfer current value data corresponding to the T signal and the H signal, the charge removal voltage control condition, etc., according to the toner type of the toner image to be transferred, are stored in the table. Read from 2.

In this embodiment, the table 2 built in the memory 511 has the environment such as temperature and humidity in which the apparatus is installed as shown in FIG. 5 in the areas LL, NN, H.
When divided into H (table 1), each of these areas L
The current value and the static elimination voltage control condition showing the best transfer efficiency at the representative points A, B, and C of L, NN, and HH are set corresponding to each of the regions. Tables 2 and 3 below show examples of the current value and static elimination voltage control conditions. Table 2 is 10
It is for a developer using a toner containing no substance having a volume resistivity of ¹² Ω · cm or less, and Table 3
Is for a developer using a toner containing a substance having a volume resistivity of 10 ¹² Ω · cm or less.

[0029]

[Table 2]

[0030]

[Table 3]

The transfer current value data read from Table 2 (Table 2 or Table 3 above) of the memory 511 is the third I /
It is output to the first digital-analog converter (D / A) 513 via the O port 512. This D / A 513
Converts the transfer current value data output from the CPU 510 via the third I / O port 512 into an analog signal and then outputs the analog signal to the first high-voltage power supply device 514, which causes the transfer charging from the high-voltage power supply device 514. The transfer current supplied to the container 5b is controlled to be a current based on the transfer current value data. On the other hand, the charge removal voltage control condition read from the table 2 of the memory 511 is similar to the transfer current, that is, the fourth I / O port 516 and the second D / A 517.
Is output to the second high-voltage power supply device 518, and thereby the inner charger 5d and the outer charger 5e are driven on / off to control the charge removal.

Next, the toner particles of the developer used in the multicolor electrophotographic copying machine embodying the present invention will be described in detail.

Toners that can be used in this embodiment are one or more of the toners of the respective colors shown in the conventional example.
A low resistance material having a volume resistivity of 10 ¹² Ω · cm or less, for example, ferric oxide, magnetite, titanium oxide, tin oxide or other oxides, or metals and carbons typified by aluminum, copper, iron, etc. %, So long as the content is 30% or more. Desirably, it is 33% or more and 70% or less. 30%
In the following cases, the current value required for the toner surface to be almost covered with resin becomes large. On the other hand, 70
If it exceeds%, the triboelectric charge amount necessary for the toner itself cannot be obtained. The developing method in which these toners can be used may be a two-component developing method or a one-component developing method. Further, there is no problem even if silica, an abrasive or the like is added to the toner obtained according to the developing method used.

Next, examples of the present invention will be specifically described.

Example 1 Of the four toners of magenta, cyan, yellow and black, polyester resin 100 was used as the magenta toner.
60 parts by weight of titanium oxide (volume average particle size 0.2 μm)
A toner having a volume average particle diameter of 8 μm was obtained by mixing parts of the toner and adding a magenta pigment and a charge control agent thereto, and a two-component developer was prepared by mixing the toner with a magnetic carrier. For the toners of other colors, toners having a volume average particle diameter of 8 μm, in which the pigments of the respective colors and the charge control agent were added to the same polyester resin, and a two-component developer in which the toner was mixed with a magnetic carrier were used.

When transferring the toner image formed by these developers, the transfer current value for each of the cyan, yellow and black toner images is selected from the above Table 2, and the transfer current value for the magenta toner image is selected from the above Table 3. did. In this way, the toner species are classified according to the presence or absence of titanium oxide,
By selecting the transfer current value from the table corresponding to the classification, a good transferred image could be obtained in all environments and in any transfer order.

At this time, the charged charge amount of the toner varies depending on the presence or absence of titanium oxide. As a result of the measurement, the magenta toner is 15 μc / g in an environment of 23 ° C., 60% room temperature and normal humidity,
The other toners were 20 μc / g.

Example 2 The magenta toner used in Example 1 was used. Further, for the black toner, 100 parts by weight of iron oxide (volume average particle diameter 0.2 μm) was mixed with 100 parts by weight of the polyester resin to control the charge. The toner to which the agent was added was kneaded to obtain a black toner having a volume average particle diameter of 8 μm. This black toner was mixed with the above-mentioned carrier to give a two-component developer. For the other cyan and yellow, the same ones as in Example 1 were used.

When transferring the toner images formed by these developers, the transfer current values for the cyan and yellow toner images are selected from the above Table 2, and the transfer current values for the magenta and black toner images are the above Table 3. Selected more. In this way, by classifying the toner types according to the presence or absence of iron oxide and titanium oxide and selecting the transfer current value from the table corresponding to that classification, good transfer images can be obtained in all environments and in any transfer order. I was able to get it.

At this time, the charged charge amount of the toner differs depending on the presence or absence of iron oxide and titanium oxide.
In the environment of normal temperature and humidity of 60 ° C. and 60%, the cyan and yellow toners were 20 μc / g, and the magenta and black toners were 15 μc / g.

Example 3 As a black toner, a one-component magnetic toner (for jumping development, volume average particle diameter 8 μm) in which magnetite which is a low resistance substance is dispersed in a resin (80% by weight of magnetite, 20% by weight of binder) is used. When used, the amount of change in the total transfer current amount of the toner with respect to the ambient humidity was small, and it was found that the data shown in Table 4 below should be stored in Table 2 of the memory 511. The toner image was transferred in the order of black, cyan, magenta, and yellow.
As is clear from Table 4, in this example, since the transfer current setting values of the region NN and the region HH can be shared, the memory capacity can be reduced.

At this time, the charge amount of the black toner was 10 μc / g in an environment of 23 ° C., 60% room temperature and normal humidity.

[0043]

[Table 4]

In the above embodiment, the transfer charger 5b was used as the transfer electric field forming means, but in the present invention, a transfer brush formed of a fine fiber having elasticity and conductivity is used instead of the transfer charging device. The present invention can be effectively applied to an image forming apparatus configured to contact the back surface of the transfer material carrier. A conductive brush in which carbon is dispersed in rayon (volume resistivity 10 ⁵ Ω · cm, fiber diameter 25 μm, density 8300 / inch) is used.
In the second embodiment of the present invention in which the same toner as that of the above-mentioned third embodiment is used, the transfer current value which can obtain a good transfer image in all environments and in any transfer order is as follows. It is shown in Tables 5 and 6.

[0045]

[Table 5]

[0046]

[Table 6]

It is needless to say that the above embodiment is merely an example of the present invention, and therefore various modifications and changes can be made as necessary.

[0048]

As described above, in the multi-color image forming apparatus according to the present invention, not only the control by the environment but also the toner type is classified according to the difference in the charged charge amount of the toner, and the transfer corresponding to the classification is performed. Since the data relating to the electric field is selected and the transfer electric field is controlled, it is possible to always form an appropriate transfer electric field under all usage environments and in any transfer order. Therefore, there is a remarkable effect that a transferred image with good image quality can always be obtained.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing a control system of a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing the overall configuration of an example of a multicolor electrophotographic copying apparatus to which the present invention can be applied.

FIG. 3 is a schematic cross-sectional view showing an enlarged transfer area and its vicinity according to the first embodiment of the present invention.

FIG. 4 is a characteristic diagram showing the relationship between temperature and saturated water content.

FIG. 5 is a diagram illustrating a state in which the environment is divided into three regions of low temperature / low humidity, normal temperature / normal humidity, and high temperature / high humidity.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 4 Rotating developing device 5 Transfer drum 5b Transfer charger 5d Inner charger 5e Outer charger 501 Transfer material carrying sheet 505 Temperature / humidity sensor 510 CPU 511 Memory

Claims (3)

[Claims] 1. An image bearing member, means for forming an electrostatic latent image on the image bearing member, and a plurality of types of toner, wherein the electrostatic latent image formed on the image bearing member is provided with toner. A developing means for adhering to form a visible image and a transferring means for transferring the visible image formed on the image carrier to a transfer material held on a transfer material carrier by an electric field; In a multicolor image forming apparatus of which at least one type has a charged charge amount of 15 μC / g or less, temperature / humidity detecting means for detecting the temperature and / or humidity inside the apparatus and the environment in which the apparatus is installed are expected. Storage unit for storing a plurality of sets of data relating to the transfer electric field in a variable range of temperature and / or humidity, the data relating to the transfer electric field being a plurality of data corresponding to the amount of charge of the toner. thing Multi-color image forming apparatus according to claim. 2. The variable range of the temperature and / or the humidity is
2. The multicolor image forming apparatus according to claim 1, wherein the multicolor image forming apparatus is divided into a plurality of areas by a substantially equal moisture content curve, and the data relating to the transfer electric field is set for each area. 3. A conductive brush composed of fine fibers having elasticity and conductivity, which is in contact with the back surface of the transfer material carrier, is used as a means for forming an electric field for transferring the visible image. The multicolor image forming apparatus according to claim 1.