JPH08286558A - Image forming device - Google Patents

Abstract

PURPOSE: To eliminate a defective transfer caused by the shrinkage and the wrinkling of a recording medium and the lowering of the resistance value thereof and to reduce the occurring rate of jam. CONSTITUTION: Toner on a recording material P on which a toner image is formed in heated, melted and fixed by a fixing roller 7. At this time, at least one of the surface temperature of the roller 7 and the carrying speed of the material P is controlled by a CPU 73 so as to satisfy the relation of TFix <120+0.7VPS when the carrying speed of the material P is defined as VPS and the surface temperature of the roller 7 is defined as TFix .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having a plurality of image forming means having different image forming systems.

[0002]

2. Description of the Related Art An image forming apparatus such as a conventional copying machine, a printer, a facsimile, etc., which uses an electrophotographic method, and an image forming apparatus composed of a plurality of image forming means (hereinafter referred to as "composite image forming apparatus"). A "color image forming apparatus" will be described. As a specific example thereof, a composite color image forming apparatus including an electrophotographic image forming unit and an inkjet image forming unit will be described.

First, an electrophotographic image forming apparatus shown in FIG. 10 will be described.

In this image forming apparatus, around the photosensitive drum 104, the primary charger 102 is sequentially arranged along the rotation direction thereof.
The exposure device 113, the developing device 103, the transfer charger 105, and the cleaner 106 are arranged, and the photosensitive drum 10
A fixing device 109 is disposed on the downstream side of 4 (the downstream side in the transport direction of the recording material P that is a recording medium).

Next, the operation of the image forming apparatus will be described. When a print signal is input, the paper feed cassette 111
The recording material P in the inside is led out onto the conveyance guide 140a by the pickup roller 112, and is conveyed to the conveyance roller pair 150a.
Thus, it is transported to the transfer charger 105 along the transport guide 140b. On the other hand, the photosensitive drum 104 is the primary charger 1
02, negatively corona-charged. Then, the surface of the negatively charged photosensitive drum 104 is exposed by the exposure device 113 according to the image data, whereby the photosensitive drum 104 loses the electric charge in the portion corresponding to the normal image portion of the image data. An electrostatic latent image is formed. This electrostatic latent image is reversely developed by the negative developer (black powder toner) carried on the developing sleeve 110. The toner image formed on the photosensitive drum 104 is transferred to the transfer charger 10
The image is transferred onto the recording material P which is corona-charged by the positive polarity 5. The recording material P on which the toner image is transferred is conveyed to the fixing device 109 through the conveyance guide 140c, and is heated and pressed at the nip between the fixing roller 107 and the pressure roller 108.

As shown in FIG. 11, the fixing device 109 is composed of a fixing roller 107 and a pressure roller 108 which are in pressure contact with each other. The fixing roller 107 is a hollow metal tube 107b having a release layer on its surface, and a heater 107a incorporated therein. The pressure roller 108 is a core metal 1
An elastic layer 108b is provided on the surface 08a, and a release layer is formed on the surface of the elastic layer 108b. In such a configuration, in order to stably fix the toner on the recording material P, the surface temperature of the fixing roller 107 is 160 to 200 ° C.
It is necessary to keep the proper temperature between.

FIG. 12 is a block diagram showing a fixing roller temperature control device. The heater 107a of the fixing roller 107 is connected to a power source 171 via a relay 172 such as an SSR. Further, on the surface of the fixing roller 107, the thermistor 163 which detects the surface temperature as a change in resistance value.
Are in contact with each other. The thermistor 163 is the CPU1
The surface temperature of the fixing roller 107, which is connected to 73 and detected by the thermistor 163, is read into the CPU 173 as a resistance value. The CPU 173 measures the fixing roller 107.
The CPU 17 compares the surface temperature of the
A DC driver 174 that opens and closes the gate of the relay 172 is connected to 3.

In the temperature control by the fixing roller temperature control device, first, the surface temperature of the fixing roller 107 is determined by the thermistor 16.
3 and read as a resistance value into the CPU 173. Next, the CPU 173 compares the read temperature with the set temperature and opens / closes the gate of the relay 172 via the DC driver 174.

In this way, the surface temperature of the fixing roller 107 is controlled to a predetermined value. For example, in an image forming apparatus with a process speed of 23 mm / sec, the surface temperature of the fixing roller 107 is set to 16 in order to fix the toner.
If 0 ° C. is required, the fixing roller 10 is set so that printing can be started immediately when a print signal is received.
It is necessary to keep the surface temperature of No. 7 at 140 ° C.
That is, when the heater 107a of about 500 W is used, the image forming apparatus which is in the warm-up state after power-on requires about 60 seconds of warm-up time. After that, by receiving the print signal, the fixing roller 107 is heated to 160 ° C. during the pre-rotation and the toner image formation.
The temperature is raised to, and the toner is fixed on the recording material P.

The composition and manufacturing method of the toner used for the above-mentioned heat fixing will be described.

The toner is a fine powder (having an average diameter of 5 to 20 μm) in which a color pigment or the like is dispersed in a binder resin.
For example, a styrene-acrylic copolymer (resin weight is 100) as a binder resin, 10 parts by weight of carbon black as a color pigment, 3 parts by weight of a charge control agent and 3 parts by weight of a release agent are mixed with a Henschel mixer. After mixing, the mixture is kneaded with a twin-screw extruder, etc., and the kneaded composition is cooled, pulverized and classified, and 1 part by weight of a fluidizing agent such as silica is externally added and mixed again to produce a toner. To do. When the toner is conveyed and coated by magnetic force in the developing process, the magnetic particles are added in the same weight as the resin and kneaded.

Next, the technique of the composite color image forming apparatus will be described. 2. Description of the Related Art Conventionally, as an output unit of image information in which a color image and a black-and-white image are mixed, an image forming apparatus using the above-described electrophotographic method, an image forming apparatus using an inkjet method, a thermal transfer method, or the like is known. Further, in order to make the most of the advantages of each method, Japanese Patent Laid-Open No. 1-11
As disclosed in Japanese Patent No. 5670, there has been proposed a composite color image forming apparatus in which an electrophotographic method for outputting a monochrome image and an inkjet method for outputting a color image are combined.

Next, the technique of the composite color image forming apparatus shown in FIG. 13 will be described.

The image forming apparatus shown in FIG. 13 is composed of a recording section E of an electrophotographic system and a recording section I of an inkjet system, and prints a black-and-white image and a color image on a recording material P in an overlapping manner. The electrophotographic recording unit E represents the black-and-white electrophotographic image forming apparatus described above, and the inkjet recording unit I is an inkjet image forming apparatus including an ink tank 120, a recording head 121, and a paper conveying unit. It represents. The paper transport unit includes transport roller pairs 150b and 150c and transport guides 140d and 140.
e and. In addition, the recording head 121 is provided with three or four nozzles whose ink ejection amount is electrically controlled and which are aligned.

Next, the operation of the composite color image forming apparatus will be described.

The recording material P on which the toner image is fixed by the electrophotographic recording section E is conveyed by a pair of conveying rollers (not shown) provided at the exit of the electrophotographic recording section E, and a conveyance guide 140d.
It moves above and is introduced into the inkjet recording unit I. The image formation in the inkjet recording unit I is performed by moving the recording material P intermittently while scanning the recording head 121 in a horizontal direction at a right angle to the conveyance direction of the recording material P when performing an ink ejection operation. Is achieved in. Further, the plurality of nozzles of the recording head 121 eject ink of three or four colors. As a result, the recording material P is image-formed by overlapping the color image portion on the monochrome image portion.

[0017]

However, in the electrophotographic image forming apparatus, the heat fixing by the fixing device 109 fixes the toner to the recording material P.
At the same time, the recording material P, which is heated to a high temperature, has a too large heating amount during fixing, so that the water content thereof is rapidly reduced, and as a result, the recording material P contracts and curls and wrinkles occur. The curls and wrinkles impede the conveyance of the recording material P and increase the occurrence of paper jam during the paper conveyance. For example, there is a problem that jams increase during post-processing such as front-back reversal when performing double-sided printing.
Furthermore, when performing double-sided printing on the recording material P, there is a problem that due to an increase in the resistance of the recording material after printing on one surface, the front-side transfer condition and the back-side transfer condition are significantly different and a transfer failure occurs. .

On the other hand, the amount of shrinkage of the recording material, such as paper, is 0.17 to 0.34% for plain paper, and it shrinks about 1 mm per 297 mm in the longitudinal direction of the A4 plate.
The fact that the amount of shrinkage of the paper is 1 mm significantly lowers the image recording accuracy. Particularly, in the composite color image forming apparatus, when the first image is formed by the electrophotographic method and the second image is recorded by, for example, the ink jet method, the first recorded image and the second recorded image match each other. The problem of not doing occurs. This image shift cannot be solved by simple alignment because the image size shrinks in the range of 0.17 to 0.34% depending on the environment and paper type.

On the other hand, when the first image is recorded by the ink jet method and the second image is recorded by the electrophotographic method, the toner is fixed after all the images are formed on the recording material P. In addition, although the image shift due to the shrinkage of the recording material P does not occur, there is a problem that wrinkles easily occur during fixing. This is the recording material P
This is because the ink that has penetrated inside expands the recording material P and the recording material P is introduced into the fixing device 109 in a wavy state.

As described above, in the conventional composite color image forming apparatus, the recording material P by heat fixing at 160 to 200 ° C. is used.
There are problems such as curl and wrinkles due to shrinkage and resistance change, more fundamental shrinkage of a recorded image, and transfer failure.

The present invention has been made in order to solve the above problems and eliminates curls and wrinkles due to shrinkage and resistance change of a recording medium, and enables good image recording even during double-sided printing. It is an object of the present invention to provide an image forming apparatus having the above structure.

[0022]

To achieve the above object, according to the image forming apparatus of the present invention, a toner image is formed on the recording medium while the recording medium is being conveyed, and the toner image on the recording medium is formed. A toner image is heated and melted by a fixing member of a fixing device to fix the toner image, the surface temperature of the fixing member is T _Fix (° C.), and the conveying speed of the recording medium is V _PS (mm / sec). At this time, control means for controlling at least one of the surface temperature of the fixing member and the transport speed of the recording medium is provided so as to satisfy the relationship of T _Fix <120 + 0.7 × V _PS. .

As an example, the method of forming a toner image on the recording medium is an electrophotographic recording method.

As another example, an electrophotographic apparatus having a plurality of image forming means of different image forming methods, and at least one of these image forming means forms a toner image on the recording medium by an electrophotographic recording method. It is a recording device.

Preferably, the toner used for forming a toner image on the recording medium is composed of at least a binder resin and a colorant, and is measured by an internal heat input compensation type differential scanning calorimeter. In the DSC curve of the toner, the endothermic peak temperature at the time of temperature rise is in the range of 55 to 120 ° C., and the difference (mW) between the height Ha of the baseline immediately after the endothermic peak and the height Hb of the endothermic peak is calculated. Measured weight M
The value (Ha-Hb) / M divided by (g) is 10 or more and 1
000 (mW / g) or less, and the control means controls at least one of the surface temperature and the transport speed so as to satisfy the relationship of T _Fix > 80 + 0.7 × V _PS .

Further preferably, the fixing device comprises a plurality of fixing members, and at least one of the fixing members is provided with a heater, a holder member for holding the heater, and a holder member and the heater. The heater is arranged at a position opposite to the other fixing member in order to apply the generated heat to the recording medium and the toner on the recording medium through the film member.

More preferably, at least one of the plurality of image forming means is a thermal transfer recording type or thermal recording type image forming means.

More preferably, at least one of the plurality of image forming means is an ink jet recording means provided with an electric converter for generating thermal energy for ejecting ink.

Further, preferably, the ink jet recording means ejects the ink from the ejection port by utilizing the film boiling generated in the ink by the thermal energy applied by the electrothermal converter.

[Operation] Based on the above configuration, the fixing member heats and melts the toner on the recording medium on which the toner image is formed to fix the toner. At this time, the control means sets the transport speed V _PS (mm / sec) of the recording medium and the surface temperature T _Fix (° C.) of the fixing member to T _Fix <120 + 0.7 × V _PS.
At least one of the surface temperature and the transportation speed is controlled so as to satisfy the above condition. As a result, shrinkage and curl of the recording medium can be eliminated, and good image recording can be performed during double-sided printing.

At least one of the image forming means for forming the toner image on the recording medium is an electrophotographic recording device of an electrophotographic system. The toner on the recording medium is composed of at least a binder resin and a colorant. In the DSC curve of the toner measured by an internal heat input compensation type differential scanning calorimeter, the endothermic peak temperature at the time of temperature rise is in the range of 55 to 120 ° C., and the height Ha of the baseline immediately after the endothermic peak is Ha. And the height H of the endothermic peak
The difference (mW) from b was divided by the measured weight M (g) (Ha
-Hb) / M is 10 or more and 1000 (mW / g) or less. In this case, the control means has T _Fix > 80 + 0.
At least one of the surface temperature and the transportation speed is controlled so as to satisfy the relationship of 7 × V _PS . As a result, good image formation without image shift or curl on the recording medium is performed while maintaining good fixability and long-term storage stability of the toner.

Further, in the image forming apparatus, the heater disposed at a position facing at least one of the fixing members applies the generated heat to the recording medium and the toner on the recording medium through the film member. A good image is formed with reduced power consumption.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. <First Embodiment> FIG. 1 is a sectional view showing an image forming apparatus according to a first embodiment of the present invention. In the figure,
In the image forming apparatus, a primary charging device 2, an exposing device 13, a developing device 3, a transfer charging device 5 and a cleaner 6 are arranged around a photosensitive drum 4 in order along a rotation direction, and a recording material which is a recording medium. A fixing device 9 is provided on the downstream side of P in the conveyance direction, and the recording material P on which the toner image is fixed by the fixing device 9 is ejected to the paper ejection tray 30 by the conveyance roller pair 50d. Further, as shown in FIG. 2, the fixing device 9 includes a fixing member (fixing roller) 7 and a pressure roller 8 which are pressed against each other.
It is comprised including. One fixing roller 7 is formed by arranging a heater 61 inside a hollow metal tube 62, and the other pressure roller 8 is provided with an elastic layer 65 on a core metal 64, and the elastic layer 65 is provided on the surface of the elastic layer 65. It is formed by applying a release layer 66. The surface temperature of the fixing roller 7 is controlled by the temperature control device shown in FIG.

FIG. 3 is a block diagram showing a temperature control device for the fixing roller 7. The heater 61 of the fixing roller 7 is an SSR.
Is connected to the power source 71 via a relay 72 such as.
A thermistor 63 that detects the surface temperature of the fixing roller 7 as a resistance value is arranged in contact with the surface of the fixing roller 7. This thermistor 63 has a CPU 7 as a control means.
3 and supplies the surface temperature of the fixing roller 7 to the CPU 73 as a resistance value change. Then, the CPU 73 compares the measured surface temperature of the fixing roller 7 with a preset temperature and drives the DC driver 74.
A DC driver 74 for opening and closing the gate of the relay 72 is connected to the PU 73.

Next, the operation will be described. When a print signal is input to the image forming apparatus, the recording material P in the paper feeding cassette 11 is first pulled out by the pickup roller 12 and conveyed to the conveyance guide 40a, the conveyance roller pair 50a, and the conveyance roller pair 50a.
The transfer guide 40b is conveyed to the transfer charger 5.

On the other hand, the surface of the photosensitive drum 4 is uniformly charged by the primary charger 2. Next, the photosensitive drum 4 is exposed by the exposure device 13 according to the print pattern, and an electrostatic latent image according to the print pattern is formed. The electrostatic latent image on the photosensitive drum 4 is developed into a toner image by the black powder toner carried on the developing sleeve 10 while being frictionally charged. The toner image formed on the photosensitive drum 4 is transferred onto the recording material P charged by the transfer charger 5.

After that, the recording material P on which the toner image is transferred
Is conveyed to the fixing device 9 through the conveyance guide 40c and is heated in the fixing nip portion between the fixing roller 7 and the pressure roller 8. As a result, the toner image on the recording material P is fixed by heating and melting the toner.

The CPU 73 reads the surface temperature of the fixing roller 7 measured by the thermistor 63 as a resistance value,
The read surface temperature is compared with a preset temperature preset in the CPU 73. Then, the CPU 73 turns on / off the relay 72 via the DC driver 74 to turn on the heater 61.
Is operated / not operated to control the surface temperature of the fixing roller 7 to a predetermined value.

In the first embodiment, the following (1) is shown.
By controlling the surface temperature of the fixing device 9 and the fixing process speed (conveyance speed of the recording material P) so as to satisfy the formula, shrinkage and curl of the recording material P, scattering of toner during backside transfer in double-sided printing, etc. Can be eliminated.

T _Fix <120 + 0.7 × V _PS (1) T _Fix : Surface temperature of the fixing roller 9 V _PS : Fixing process speed (conveying speed of the recording material P) Conventionally, the fixing process speed is 23 mm / sec. In this case, a fixing temperature of 160 ° C. was required, but in the first embodiment, the recording material P shrinks or curls by fixing the toner image at a temperature of 136 ° C. or less that satisfies the expression (1). Can be eliminated. That is, when the process speed is 23 mm / sec, from the above formula (1), 1
It is desirable to carry out at 36 ° C. or lower (see FIG. 4). Therefore, after the power is turned on, the surface temperature of the fixing roller 7 is about 106
If the temperature is kept at .degree. C. and the fixing roller 7 is heated to 136.degree. C. during the pre-rotation after the print signal is transmitted and during the toner image formation, the toner can be fixed without shrinking the recording material P. Also, the process speed is 64mm
/ sec, the surface temperature of the fixing roller 7 is about 165 ° C
Even if the temperature is raised to 0, the same result can be obtained without shrinking the recording material P.

Next, details of the equation (1) will be described.

In order to suppress the shrinkage amount of the recording material P at the time of fixing the toner image to an appropriate amount, the CPU 7 should satisfy the above expression (1) in the relationship between the surface temperature and the process speed.
It has been found that controlling the heater 61 by 3 is effective.

That is, FIG. 4 which does not satisfy the above equation (1).
Since the amount of heat applied to the recording material P is large up to the area A of
Due to the shrinkage or curl of the recording material P or the increase of the resistance value of the recording material P, the printing accuracy is lowered, the jam ratio is increased, or the transfer scattering occurs at the time of the back surface printing. The shrinkage or curl of the recording material P or the increase of the resistance value of the recording material P is applied from the fixing roller 7 while the recording material P passes through the fixing nip portion where the fixing roller 7 and the pressure roller 8 are in contact with each other. The amount of heat that is generated has a large relationship. Therefore, as the process speed is higher or the surface temperature of the fixing roller 7 is lower, the amount of heat applied to the recording material P decreases and the amount of shrinkage decreases. Therefore, if the amount of heat applied to the recording material P is controlled so as to be within the area B shown in FIG. 4, the amount of heat applied to the recording material P will be below a certain amount, and the amount of shrinkage can be suppressed below a certain amount.

Under the conditions satisfying the above expression (1), the amount of shrinkage of about 0.2 mm or less per 297 mm in length can be suppressed in the A4 size of general plain paper. In the region of the formula (1) in which the amount of heat applied to the recording material P is sufficiently small, the amount of moisture absorption in the recording material P due to heating decreases, so that wrinkles and curls or increase in resistance value of the recording material also decrease at the same time. As for the curl, a good result that the amount of curling up when the recording material P immediately after fixing is placed on a flat surface is 1 cm or less is obtained. The increase in resistance of the recording material P, which has been several orders in the past, is reduced to 1 order or less. Further, since the shrinkage amount of the recording material P varies depending on the moisture absorption amount before fixing, the recording material P left for 5 hours or more in the environment of temperature 23 ° C. and humidity 60% is used as the measurement condition. The container 9 was measured under the conditions that the fixing nip was about 3 mm and the total pressure applied at both ends was 5 kgf.

Further, as the control means satisfying the condition of the expression (1), it is possible to change the carrying speed at the time of fixing in accordance with the surface temperature of the fixing roller 7, for example. That is,
Immediately after finishing the printing operation, the surface temperature of the fixing roller 7 may exceed the set temperature. In such a case, the shrinkage amount can be suppressed below a certain amount by fixing the toner on the recording material P at a faster process speed so as to satisfy the expression (1) based on the surface temperature of the fixing roller 7. it can. On the other hand, when the surface temperature of the fixing roller 7 does not reach the set temperature immediately after the image forming apparatus is started, the recording material P is controlled by controlling the process speed slowly.
It is possible to secure the fixing to the sheet and suppress the shrinkage amount.

Further, in the continuous print mode in which the same image is continuously printed, it is a better control method to raise the control temperature and increase the process speed within the range satisfying the expression (1). .

As the fixing roller 7 of the present invention, the metal tube 62 provided with the release layer is used, but it may be composed of the elastic layer 65 and the release layer 66 like the pressure roller 8. Also,
The same applies to the configuration in which the heaters 61 are arranged above and below.

Further, according to the present invention, since the heating temperature can be set low, the surface temperature of the fixing roller 7 in the standby state is 106 ° C. in the above example. As a result, there is a great advantage that the warm-up time can be shortened and the overall power consumption including during printing and standby can be significantly reduced. In addition, temperature rise in the image forming apparatus can be suppressed, and temperature fluctuations of other units such as drum characteristics and toner characteristics can be suppressed. Further, since the heat-resistant temperature of the constituent members of the fixing device 9 can be lowered, the selection range of materials is expanded, which is advantageous in terms of cost.

In the present invention, the object of the present invention can be achieved more effectively by using a toner having the following characteristics. Next, the prescription example will be shown and the toner characteristics will be described.

In the toner of the present invention, the measured DSC curve (see FIG. 5) shows that when the peak of the endothermic amount (mW) at the time of temperature rise is in the range of 55 to 120 ° C., the baseline immediately after this peak is obtained. A value (Hb-Ha) obtained by dividing the difference (mW) between the height Ha and the height Hb of the peak by the measured weight M (g).
/ M is 10 or more and 1000 (mW / g) or less, the toner is 80 + 0.7 × V _PS <T _Fix <120 + 0.7 × V _PS (3) under the condition of formula (3) described later. It is possible to eliminate defects such as shrinkage and curl of the recording material P and to achieve good fixing.

Hereinafter, a toner prescription example for obtaining the above DSC characteristics will be described.

Binder resin: Styrene acrylic or polyester resin having a glass transition point of 55 ° C. 100 parts by weight Colorant: carbon black 5 parts by weight Charge control agent: In the case of negative polarity, a negatively chargeable charge control agent (azo dye 2 parts by weight or a positively chargeable charge control agent (eg Nigrosine) in the case of positive polarity 2 parts by weight Low temperature melting agent: A low melting point hydrocarbon wax (endothermic peak temperature about 108 ° C) 5 parts by weight Alternatively, 10 parts by weight of B higher fatty acid (endothermic peak temperature of about 67 ° C.) As a toner preparation procedure, the above materials are first mixed in a blender and melt-kneaded in a twin-screw extruder heated to 130 ° C. After cooling the kneaded product, it is roughly pulverized by a hammer mill, and the coarsely pulverized product is further finely pulverized by a jet mill.
The finely pulverized product obtained is strictly classified by a multi-division classifier using the Coanda effect to obtain toner particles having a desired particle size. 1.0% by weight of dry silica (B
ET specific surface area of 130 m ² / g) was added and mixed in a mixer to obtain a weight average particle diameter (D4) of 7.0 μm.
m toner can be obtained. Depending on the developing device configuration, it is necessary to impart magnetism to the toner. In that case, 100 parts by weight of magnetic particles such as ferrite are mixed as a material. However, in this case, since the magnetic material itself is black, the coloring agent is not mixed.

In the DSC measurement applied in the present invention, the heat exchange of the toner is measured and the thermal behavior of the toner is observed. Therefore, in principle, the measurement is performed with a highly accurate internal heat input compensation type differential scanning calorimeter. There is a need to. For example, DSC-7 manufactured by Perkinermer can be used. The measuring method is ASTMD
3418-82 and the DS used in the present invention
As the C curve, a DSC curve measured when the temperature is raised once and the previous history is removed, and then the temperature is lowered and raised in the temperature range of 10 ° C./min and the temperature of 0 to 200 ° C. is used. The endothermic peak temperature is a peak temperature in the plus direction on the DSC curve, and means a point at which the differential value of the peak curve becomes 0 when the differential value changes from positive to negative.

As the compound to be mixed in order to obtain the peak of the toner of the present invention, a low melting point hydrocarbon wax and its derivative, a higher fatty acid and its derivative, a low point crystalline polymer compound and the like are used. At this time, the endothermic peak temperature in the DSC curve of the compound itself to be mixed is also preferably 55 to 120 ° C.

When the endothermic peak temperature is less than 55 ° C,
The toner is likely to thermally aggregate and cause blocking. Also,
If the temperature exceeds 120 ° C., a large amount of heat is required to fix the toner, and under the condition of the formula (1), fixing failure occurs. More preferably, the endothermic peak temperature is 60.
It is desirable to be in the range of 110 ° C.

The difference (mW) between the height Ha of the baseline immediately after the endothermic peak and the height Hb of the endothermic peak is measured by weight M.
If the numerical value (Ha-Hb) / M divided by (g) is less than 10, a large amount of heat is required to fix the toner, and the fixing condition becomes poor under the fixing conditions of the formula (1). on the other hand,
When the numerical value (Ha-Hb) / M exceeds 1000, the toner is offset to the fixing roller 7 during fixing and the fixing roller 7
Also, when the toner is stored for a long period of time, blocking occurs when the recording material P is contaminated or is easily thermally aggregated.

Therefore, a minimum amount of heat is required to fix a toner formulated so that it can be stored for a long period of time. According to the experiment, it was found that the fixing condition satisfying at least the formula (2) is necessary.

T _Fix > 80 + 0.7 × V _PS (2) T _Fix : Surface temperature of fixing roller 7 V _PS : Fixing process speed (conveying speed of recording material) Therefore, this equation (2) is expressed by the above (1). Together with the equation, it can be summarized into the following equation (3).

80 + 0.7 × V _PS <T _Fix <120 + 0.7 × V _PS (3) As a result, the influence of shrinkage or the like on the recording material is suppressed, the long-term storage stability of the toner is extended, and good fixing property is obtained. be able to.

Further, in the toner according to the present invention,
In order to improve charge stability, developability, fluidity and durability, it is preferable to mix inorganic fine particles. Various types of inorganic fine particles can be used, but those selected from silica, alumina, and titania are particularly effective.

The above-mentioned inorganic fine particles have a specific surface area of 50 to 400 m ² / g by nitrogen adsorption measured by the BET method.
Those in the range of (particularly 130 m ² / g) give good results. Inorganic fine particles 0.01 per 100 parts by mass of toner
-8 mass parts, preferably 0.1-5 mass parts should be used.

Conventionally, a large amount of heat is required to fix the toner, and as a result, there have been problems such as shrinkage and curling of the recording material, and defective transfer during backside printing.

However, according to the present invention, problems such as shrinkage and curl of the recording material can be solved by controlling the surface temperature and the conveying speed within the range of the condition satisfying the expression (1).

Further, by using the toner having the proper DSC characteristics described above and controlling the fixing temperature so as to satisfy the condition of the formula (3), the shrinkage is eliminated and at the same time, the long-term storability of the toner is increased, Good fixability can be realized. <Second Embodiment> FIG. 6 is a sectional view of a composite color image forming apparatus according to a second embodiment. A case where a black and white image is formed by the electrophotographic recording unit E and then a color image is formed by the inkjet recording unit I will be described.

First, the configuration of the image forming apparatus according to the second embodiment will be described. In the electrophotographic recording section E, a primary charger 2, an exposure device 13, a developing device 3, a transfer charger 5 and a cleaner 6 are arranged around the photosensitive drum 4 in order along the rotation direction of the photosensitive drum 4, and the transfer is performed. The fixing device 9 for fixing the toner image transferred to the recording material P by the charging device 5 is provided on the downstream side in the conveying direction of the recording material P. Further, the inkjet recording unit I includes a recording material P derived from the ink tank 20, the recording head 21, and the electrophotographic recording unit E.
And a conveyance roller pair 50b, a conveyance guide 40e, and a conveyance roller pair 50c.

The fixing device 9 of the electrophotographic recording section E is controlled to a temperature and speed of a low heating amount which satisfies the expression (1), and the shrinkage of the recording material P is suppressed so that the image shift is prevented and the image formation is performed. To do. Further, by using the toner having the desired DSC characteristics described in the first embodiment and controlling the temperature and speed to satisfy the above expression (3), it is possible to realize even better fixability.

Next, the operation will be described. When a print signal is input to the image forming apparatus after the power is turned on, the recording material P in the paper feed cassette 11 is picked up by the pickup roller 1.
It is led out onto the conveyance guide 40a by 2 and is conveyed to the transfer charger 5 along the conveyance guide 40b by the conveyance roller pair 50a.

On the other hand, the photosensitive drum 4 is charged by the primary charger 2. The photosensitive drum 4 is exposed by the exposure device 13, and an electrostatic latent image is formed on the photosensitive drum 4. The electrostatic latent image is developed by the triboelectrically charged black powder toner carried on the developing sleeve 10. The toner image formed on the photosensitive drum 4 is transferred onto the recording material P charged by the transfer charger 5.

After that, the recording material P on which the toner image is transferred
Is conveyed to a fixing device 9 having a fixing roller 7 and a pressure roller 8 along a conveyance guide 40c, and the fixing roller 7
In the fixing nip between the pressure roller 8 and the pressure roller 8, the toner is heated to melt and fix the toner. The relationship between the fixing temperature and the conveying speed of the recording material P at this time is set so as to satisfy the expression (1), and is devised so that the recording material P does not shrink. In this way, the recording material P on which the electrophotographic recording has been completed
Is transported on a transport guide 40d by a transport roller pair (not shown) provided at the exit of the electrophotographic recording unit E, and is transported to a position corresponding to the recording head 21.

Further, the structure of the ink jet recording section I will be described with reference to FIG. The inkjet recording unit I ejects ink from the recording head 21 to generate a recording material P.
The inkjet recording method is used for recording. That is, the recording head 21 has a plurality of nozzles arranged in an array in which the ink ejection amount is adjusted by electrical control. The recording head 21 is scanned in the direction perpendicular to the traveling direction of the recording material P, and The ink is ejected by intermittently moving P. As a result, an image is formed on the recording material P by the recording head 21. In addition, the recording head 21
, A plurality of nozzles are arranged in line, and ink of three or four colors can be ejected, so that a color image can be recorded.

Further, the recording head 21 generates a fine liquid discharge port (orifice), a liquid passage partially having an energy acting portion, and droplet forming energy for discharging the liquid from the energy acting portion. Energy generating means. Since the liquid ejection port has a resolution of 300 dpi, the distance from the center of one liquid ejection port to the center of the next liquid ejection port of the same color is about 84.7 μm.

As the energy generating means, a recording method using an electromechanical transducer such as a piezo element, a recording method in which droplets are ejected by a heat generation effect of irradiation of electromagnetic waves such as a laser, or a heating element having a heating resistor is used. There is a recording method in which a liquid is heated and discharged by an electrothermal converter such as.

Among them, the recording head 21 used in the ink jet recording system for ejecting a liquid by thermal energy can arrange the liquid ejection ports for ejecting the recording liquid droplets at a high density, so that it has a high resolution. It is possible to keep a record. In particular, the recording head 21 using the electrothermal converter as the energy generating means can be easily made compact, and has the advantages of the IC technology and the microfabrication technology, which have been remarkably improved in technology and reliability in the recent semiconductor field. Are advantageous because they can be fully utilized, high-density mounting is easy, and the manufacturing cost is low.

As shown in FIG. 7, the ink jet recording section I has a plurality of liquid ejection ports (ink ejection ports) in the recording head 21, and each of cyan C, magenta M, yellow Y and black BK. It is composed of a head for color ink. One liquid ejection port is the recording head 2
Ink is ejected 300 times while 1 moves along the guide (not shown) in the direction of arrow b in FIG. 7 by a certain distance, for example, 25.4 mm. Each ink has an ink supply tube 9
It is supplied to each recording head 21 from the ink tank 20 via 0. The recording head 21 is mounted on a carriage 91. The carriage 91 is fixed to a part of a belt 94 stretched between a drive pulley 92a and a driven pulley 92b, and is raised in the direction of arrow b along the guide. Driven with precision. The ink tank 20 is fixed to a part of a belt 95 stretched between a driving pulley 93a and a driven pulley 93b, and moves in the direction of arrow b along a guide (not shown) like the recording head 21. Carriage 91 on belt 94
Is fixed and the ink tank 20 is fixed to the belt 95, the stress applied to the ink supply tube 90 is eliminated, and the ink tank 20 which is a relatively heavy object is driven separately from the carriage 91. The propagation path of the vibration to the recording head 21 side such as the vibration generated by the movement of is cut off.

The recording material P is sandwiched between the conveying roller pair 50b and the conveying roller pair 50c, and recording is performed by the recording head 21 arranged between the conveying roller pair 50b and the conveying roller pair 50c. The transport speed of the transport roller pair 50c is set to be slightly higher than the transport speed of the transport roller pair 50b, and the recording material P is stretched between both roller pairs to maintain the tension. ing. Further, in order to maintain the tension of the recording material P, the recording material P may be attracted to the platen 96 having a flat surface portion by electrostatic attraction or air.

Then, according to the image signal, the recording head 21
Starts recording from the left end side of the recording material P in the stopped state, proceeds like the recording line L shown in FIG. 7, reaches the right end, and when recording for one line is completed, the left end together with the carriage 91 and the ink tank 20. Return to. During this time, the recording material P
Is conveyed by the conveying roller pair 50b and the conveying roller pair 50c in the direction of the arrow a in FIG. 7 by a distance 1 for one line, and is stopped again and recording for one line is similarly performed. By repeating such an operation, color recording is performed on the recording material P.

The recording material P after recording is discharged to the paper discharge tray 30 (see FIG. 6) by the pair of conveying rollers 50c.

As described above, clear black and white recording can be performed on the recording material P by the electrophotographic recording section E, and inexpensive color recording can be performed on the recording material P by the ink jet recording section I.

In the conventional electrophotographic recording means, the recording material P is contracted by about 0.25% (0.74 mm per longitudinal direction of A4 size paper) due to fixing. It was difficult to match the images. On the other hand, the shrinkage of the recording material P is reduced by 0.07 to 0.1 by fixing with a heating amount that satisfies the above expression (1).
% (0.2 to 0.3 m per length of A4 size paper)
m) or less, and the image shift in the electrophotographic recording section E and the inkjet recording section I can be reduced.

Further, since the curl and wrinkle of the recording material P can be made extremely small, the position alignment of the tip of the recording material P can be stably performed. Furthermore, since the overall heating amount for the recording material P is reduced, the power consumption is also reduced,
It is possible to suppress an increase in temperature inside the composite color image forming apparatus and suppress a rise in temperature of the recording head 21. Furthermore, by using the toner having the desired DSC characteristics described above, the long-term storage stability of the toner is improved, and good fixability can be obtained.

Further, the present invention has the same effect when applied to a composite color image forming apparatus for electrophotographic recording after ink jet recording as shown in FIG. That is, the composite color image forming apparatus shown in FIG. 8 does not have the problem of image misregistration as shown in FIG. 6, but when the recording material P that has absorbed the ink after inkjet recording is fixed, the ink is locally recorded on the portion where the ink is recorded. There is a problem that it is easy to cause shrinkage, curl, or wrinkles. However, by satisfying the above expression (1) for the relationship between the conveyance speed of the recording material P of the present invention and the surface temperature of the fixing roller 7, it is possible to suppress shrinkage, wrinkles, and curl that occur during ink drying, and
As in the case of the inkjet recording method shown in FIG. 7, it is possible to reduce power consumption and prevent temperature rise in the composite color image forming apparatus.

As described above, in the composite color image forming apparatus, by fixing so as to satisfy the expression (1), it is possible to suppress shrinkage, curl, and wrinkles of the recording material P, and realize good image recording. Further, by fixing the toner having the desired DSC characteristics so as to satisfy the expression (3), the storability of the toner is increased and a good fixing property is obtained. <Third Embodiment> In the above-described second embodiment, an electrophotographic system and an inkjet recording system are exemplified as a plurality of image forming means having different image forming systems, but the present invention is limited to the inkjet recording system. It is not necessary to use, for example, a thermal recording system or a thermal transfer recording system, and the same effect can be obtained.

Further, although the ink jet recording system is used as the recording means in the second embodiment, it is more preferable to have the following constitution in this ink jet recording system.

That is, the electrothermal converter is energized in response to a recording signal, and the thermal energy applied by the electrothermal converter causes the film boiling generated in the ink to be used to grow and shrink the bubbles in the ink. Ink is ejected from the liquid ejection port to perform recording.

Regarding its typical structure and principle, see, for example, US Pat. Nos. 4,723,129 and 474,079.
What is carried out using the basic principle disclosed in No. 6 is preferred. This method can be applied to either a so-called on-demant type or a continuous type, but particularly in the case of the on-demand type, it is arranged corresponding to the sheet or liquid path holding the liquid (ink). By applying at least one drive signal which gives a rapid temperature rise exceeding nucleate boiling in response to the recorded information to the electrothermal converter being formed, thermal energy is generated in the electrothermal converter, and the recording head 21 This is effective because film boiling is caused on the heat-acting surface and the bubbles in the liquid corresponding to this drive signal in a one-to-one relationship can be formed. Due to the growth and contraction of the bubbles, the liquid is ejected through the ejection opening to form at least one droplet. It is more preferable to make this drive signal into a pulse shape, because the bubble growth and contraction are immediately and appropriately performed, so that the ejection of the liquid with excellent responsiveness can be achieved.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable.

If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise of the heat acting surface are adopted, further excellent recording can be performed.

As the constitution of the recording head 21, other than the combination constitution of the discharge port, the liquid passage and the electrothermal converter (the linear liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications. The present invention also includes configurations using US Pat. Nos. 4,558,333 and 4,459,600, which disclose a configuration in which the heat acting portion is arranged in a bending region.

Further, Japanese Patent Application Laid-Open No. 59-123670 discloses a structure in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy. The effect of the present invention is effective even if the structure is based on Japanese Patent Application Laid-Open No. 59-138461, which discloses a structure in which the holes correspond to the ejection portions. That is, regardless of the form of the recording head 21, according to the present invention, recording can be reliably and efficiently performed.

Further, the present invention can be effectively applied to a full line type recording head having a length corresponding to the maximum width of a recording medium which can be recorded by the image forming apparatus.

As such a recording head, a combination of a plurality of recording heads to satisfy the length thereof or a structure of one recording head integrally formed may be used.

In addition, even in the case of the serial type described above, by being mounted on the recording head 21 fixed to the carriage 91 or the carriage 91, electrical connection with the apparatus main body and supply of ink from the apparatus main body are possible. The present invention is also effective when a replaceable chip-type recording head or a cartridge-type recording head in which an ink tank is integrally provided in the recording head itself is used.

Further, as the ink jet recording method used in the image forming apparatus of the above-described embodiment, it is preferable to add a recovering means for the recording head, a preliminary auxiliary means, etc. because the effect of the present invention can be further stabilized. It is a thing. Specific examples thereof include capping means, cleaning means, pressurizing or suctioning means for the recording head, preheating means using an electrothermal converter or another heating element or a combination thereof, and recording. Performing a preliminary ejection mode for performing another ejection is also effective for stable recording.

Regarding the type or number of recording heads mounted on the carriage, for example, only one is provided corresponding to a single color ink, or a plurality of inks having different recording colors and densities are provided. Correspondingly, a plurality may be provided. That is, for example, the recording mode of the inkjet recording unit I is not limited to the recording mode of only the mainstream color such as black, but may be any of a plurality of combinations that integrally configure the recording head. The present invention can also be applied to an apparatus provided with at least one of full colors by color mixing.

In addition, in the above-described embodiments, the ink is described as a liquid, but an ink that solidifies at room temperature or lower and that softens or liquefies at room temperature may be used. Or, in the ink jet recording method, it is general to control the temperature of the ink itself within a range of 30 ° C. or higher and 70 ° C. or lower to control the temperature of the ink so that the viscosity of the ink is within a stable ejection range. A liquid ink may be used.
In addition, in order to prevent the temperature rise due to the thermal energy from being positively used as the energy for changing the state of the ink from the solid state to the liquefied state, or to prevent the evaporation of the ink, the ink is solidified in a standing state, Ink that is liquefied by heating may be used. In any case, heat energy such as ink that is liquefied by applying heat energy according to the recording signal and liquid ink is ejected, or ink that has already started to solidify when it reaches the recording material P is used. The present invention is also applicable to the case of using an ink that has a property of liquefying only after being applied.

The ink in such a case is described in JP-A-55-55.
As described in JP-A-56847 or JP-A-60-71260, a form in which the electrothermal converter is opposed to a liquid sheet or a solid material held in the recesses or through holes of the porous sheet. May be In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

Particularly, in the present invention, by lowering the fixing energy of the electrophotographic recording section, the temperature rise in the image forming apparatus is suppressed, and it has an advantageous effect on the control of ink jet recording.

The image forming apparatus may be used as an image output terminal device of information processing equipment such as a computer, or may be a copying machine combined with a reader or the like.
Further, it may take the form of a facsimile machine having a transmission / reception function. <Fourth Embodiment> In the fourth embodiment, the first
A case will be described in which the film type fixing device shown in FIG. 9 is used instead of the fixing device used in the embodiment and the second embodiment. The configuration and operation of the image forming apparatus other than the fixing device are in accordance with the first embodiment and the second embodiment.

FIG. 9 shows the structure of a film-type fixing device. The fixing device includes a fixing member and a pressure roller 8. The fixing member includes a fixing film 81 as a film member, a ceramic heater 82, and a heater support member 83 as a holder member, and the pressure roller 8 is provided. Is a cored bar 64 provided with an elastic layer 65.
The heat generated in the ceramic heater 82 is efficiently applied to the toner on the recording material P through the fixing film 81. Further, the ceramic heater 82 is formed by applying a resistance layer on a ceramic substrate, wiring the layers, and then applying a glass layer. A thermistor is also formed on the ceramic substrate at the same time, and the fixing temperature is adjusted by monitoring the temperature on the ceramic substrate.

Also in the case of the film type fixing device, by setting and controlling the surface temperature and the conveying speed so as to satisfy the above expression (1), in the electrophotographic recording apparatus, the recording material P is prevented from shrinking or curling. Good image recording can be performed without causing any problems. Further, the composite color image forming apparatus can form an image without image shift. Since the film type fixing device can instantly heat the nip formed by the fixing film 81 and the pressure roller 8 being in contact with each other, the warm-up time described above is not necessary in the first embodiment. Therefore, the amount of heat radiated to the outside of the fixing device is small, the temperature in the image forming apparatus can be lowered, and the power consumption can be significantly reduced.

However, since the warm-up time is not necessary, the amount of heat applied to the recording material P is insufficient immediately after the image forming apparatus is started. That is, when the temperature of the pressure roller 8 and the fixing member are extremely different, the heat amount given to the recording material P satisfies the formula (1) because the low temperature pressure roller 8 takes away the heat of the high temperature fixing member. do not do. Another reason for not satisfying the expression (1) is that the temperature detecting thermistor position is not on the film surface. Therefore, the surface temperature of the film-type fixing device is set to 2 immediately after the start-up by the control means.
The temperature is set to be as high as 0 ° C. to 50 ° C., or the conveying speed of the recording material P is set to be slow. And the control means
If the formula (1) is finally satisfied as the temperature of the pressure roller 8 rises, the surface temperature and the conveying speed of the film fixing device may be reset. By doing so, the amount of heat applied to the recording material P immediately after start-up does not satisfy the expression (1), but since the amount of heat applied to the recording material P is lower than before, shrinkage of the recording material P or Good printing can be performed without curling.

As described above, in the fourth embodiment, even when the film type fixing device is used,
The control means controls the surface temperature of the fixing member and the conveyance speed of the recording material P so as to satisfy the expression (1). Furthermore, by using the toner having the above-described desired DSC characteristics, problems such as shrinkage and curl of the recording material P and transfer failure at the time of back surface printing due to a decrease in resistance of the recording material P are solved, and good image formation is achieved. It can be carried out. Further, also in the composite color image forming apparatus, good recording without image shift or wrinkle can be performed, temperature rise in the image forming apparatus can be eliminated, and power consumption can be significantly reduced.

In the above embodiment, the combination of the electrophotographic recording means and the ink jet recording means was explained as the composite color image forming apparatus, but the invention is not limited to this, and for example, the electrophotographic recording means and the thermal transfer recording means or the electrophotographic recording means. A combination of recording means and heat-sensitive recording means may be used.

[0104]

As described above, according to the present invention,
Using the control means, at least one of the transport speed (V _PS ) of the recording medium and the surface temperature (T _Fix ) of the fixing member is set to T _Fix <1.
Since the control is performed so as to satisfy the condition of 20 + 0.7V _PS , it is possible to eliminate the shrinkage of the recording medium, wrinkles, and the transfer failure due to the resistance reduction of the recording medium which have occurred at the time of fixing, and the good print with a small jam occurrence rate. Will be possible.

Further, in a plurality of image forming apparatuses having different image forming systems, even when printing is performed by a plurality of recording units, good recording without image misalignment is possible.

Furthermore, since the image formation is performed under the above-mentioned conditions, there are various advantages such as reduction of power consumption of the image forming apparatus and expansion of selectivity of constituent members of the fixing device.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a cross-sectional view showing the same fixing device.

FIG. 3 is a control block diagram for performing temperature control of the fixing device of the above.

FIG. 4 is a characteristic diagram showing a relational expression (1) between a conveyance speed of a recording material and a surface temperature of a fixing roller.

FIG. 5 is a diagram showing a DSC characteristic of toner.

FIG. 6 is a schematic structural sectional view showing a second embodiment of the image forming apparatus according to the invention and showing a case where inkjet recording is performed after electrophotographic recording.

FIG. 7 is a perspective view showing an inkjet recording unit of the above.

FIG. 8 is a schematic structural sectional view showing a second embodiment of the image forming apparatus according to the invention and showing a case where electrophotographic recording is performed after ink jet recording.

FIG. 9 is a sectional view showing a film type fixing device of a fourth embodiment of the image forming apparatus according to the invention.

FIG. 10 is a sectional view showing an example of a conventional image forming apparatus.

FIG. 11 is a cross-sectional view showing the fixing device of the above.

FIG. 12 is a control block diagram for performing temperature control of the fixing device of the above.

FIG. 13 is a cross-sectional view showing another example of a conventional image forming apparatus, in which inkjet recording is performed after electrophotographic recording.

[Explanation of symbols]

7 Fixing Roller 8 Pressure Roller 9 Fixing Device 12 Pickup Roller 61 Heater 72 Control Means (Relay) 73 Control Means (CPU) 74 Control Means (DC Driver) 81 Film Member (Fixing Film) 82 Heater 83 Holder Member (Heater Support Member) ) E electrophotographic recording means (electrophotographic recording part) I inkjet recording means (inkjet recording part)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kenya Ogawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (8)

[Claims] 1. An image forming apparatus in which a toner image is formed on a recording medium while the recording medium is being conveyed, and the toner image on the recording medium is heated and melted by a fixing member of a fixing device to fix the image. Assuming that the surface temperature of the member is T _Fix (° C.) and the transport speed of the recording medium is V _PS (mm / sec), the fixing member is fixed so that the relationship of T _Fix <120 + 0.7 × V _PS is satisfied. An image forming apparatus comprising: a control unit that controls at least one of a surface temperature and a conveyance speed of the recording medium. 2. A method for forming an image on the recording medium is
The image forming apparatus according to claim 1, wherein the image forming apparatus is an electrophotographic recording system. 3. An electrophotographic recording apparatus having a plurality of image forming units of different image forming systems, at least one of which is for forming a toner image on the recording medium by an electrophotographic recording system. The image forming apparatus according to claim 1, wherein: 4. The toner used when forming a toner image on the recording medium is composed of at least a binder resin and a colorant, and is measured by an internal heat input compensation type differential scanning calorimeter. In the DSC curve of the toner, the endothermic peak temperature at the time of temperature rise is in the range of 55 to 120 ° C., and the difference (mW) between the baseline height Ha immediately after the endothermic peak and the endothermic peak height Hb is measured. Value divided by weight M (g) (Ha-H
b) / M is 10 or more and 1000 (mW / g) or less, and further, the control means controls the surface temperature and the transport speed so as to satisfy the relationship of T _Fix > 80 + 0.7 × V _PS . The image forming apparatus according to claim 1, wherein at least one of them is controlled. 5. The fixing device includes a plurality of fixing members, and at least one of the fixing members is provided with a heater, a holder member for holding the heater, and the holder member and the heater. A film member, and the heater is arranged at a position opposite to the other fixing member so as to apply the generated heat to the recording medium and the toner on the recording medium through the film member. The image forming apparatus according to claim 1. 6. The image forming apparatus according to claim 3, wherein at least one of the plurality of image forming units is a thermal transfer recording type or a thermal recording type image forming unit. 7. At least one of the plurality of image forming means is an inkjet recording means provided with an electric converter for generating thermal energy for ink ejection. Image forming device. 8. The ink jet recording means causes the ink to be ejected from an ejection port by utilizing the film boiling generated in the ink by the thermal energy applied by the electrothermal converter. Image forming device.