JPH04318580A - Prefixation processor for copying machine - Google Patents

Abstract

PURPOSE:To prevent image flowing and the overheat of a transcription paper by measuring the characteristic of the transcription paper such as smoothness and electric resistance and executing processing in accordance with the characteristic to an unfixed toner image. CONSTITUTION:A copying machine in which a latent image on a photosensitive body 1 is developed to be a toner image with liquid developer and the toner image is transcribed to the transcription paper P and fixed by heating the transcription paper P by a heating means 14 which is brought into contact with the transfer paper P is provided with a potential impressing means 13 for impressing the potential having a reverse polarity to toner at least on the back surface of the transcription paper P which carries the transcribed toner image T1, a characteristic measuring means 18 for measuring the characteristic of the transcription paper, which is disposed in a carrying path 11 for the transcription paper before the toner image is transcribed from the photosensitive body 1, and a control means 19 for controlling the actuation of the potential impressing means in accordance with the characteristic of the transcription paper P which is measured by the means 18.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing pretreatment device for a wet development transfer type copying machine.

0002

2. Description of the Related Art Referring to FIG. 1, an example of a wet development transfer type copying machine will be described. Around the photoreceptor drum 1 as an electrostatic latent image carrier that rotates clockwise, there is a charger 2 that uniformly charges the photoreceptor along the rotation direction.
, an exposure section 3 that irradiates the charged photoreceptor drum 1 with an original image on a contact glass to form an electrostatic latent image, an eraser 4 that removes excess charge after exposure, and a liquid developer consisting of toner and solvent. A wet developing device 5 supplies the electrostatic latent image to the surface of the photoreceptor to turn it into a visible image (toner image), and a toner image is fed from a paper feeding device 6 to a transfer paper P that is brought into close contact with the photoreceptor drum. A transfer charger 7 for transferring, a separation roller 8 for separating the transfer paper after the toner image transfer from the photoreceptor drum surface, a cleaning device 9 for cleaning the drum surface after the toner image transfer, and a static neutralizer for removing residual charge on the photoreceptor. The lamps 10 are arranged in this order.

[0003] An electrostatic latent image is formed on the photoreceptor drum 1 charged by the charger 2 in the exposure section 3, and this electrostatic latent image is exposed to a liquid developer consisting of a solvent and toner in a wet type developing device 5. The toner is supplied and visualized into a toner image. The transfer paper fed from the paper feeder 6 is temporarily stopped by registration rollers 12 disposed on the transfer paper conveyance path 11 between the paper feeder 6 and the transfer charger 7, and waits until it reaches the photoreceptor drum. The photoreceptor drum is re-fed at the same timing as the toner image, and is brought into close contact with the circumferential surface of the photoreceptor drum, so that the toner image is transferred. The transfer paper, on which the toner image has been transferred and separated from the photosensitive drum 1, is sent to the heating means 14 after excess solvent on the toner image bearing surface is removed by a solvent removing means 13A serving as a pre-fixing treatment device. After the toner image is heated and fixed by this means, it is sent out of the machine by a pair of transport rollers 15.

Referring to FIG. 18, an example of the solvent removing means 13A will be described. Transfer paper P separated from the photosensitive drum 1 by the separation roller 8 is guided by guide plates 8a and 16 and sent to the solvent removing means 13A. . This means 13A consists of a blotter roller 13a that contacts the toner image bearing surface of the transfer paper P, and a backup roller 13b that presses the transfer paper against this roller, and removes excess solvent remaining on the unfixed toner image bearing surface. Remove. Blotta roller 1
3a is made of a hygroscopic material such as nonwoven fabric.

Referring to FIG. 18, an example of the heating means 14 will be explained. Path 17 for transfer paper P carrying an unfixed toner image
A heating roller 14a and a pressure roller 14b are placed in pressure contact with each other, sandwiching the roller 14a and the pressure roller 14b. The overheating roller 14a is in direct contact with the unfixed toner image bearing surface of the transfer paper, and has a built-in heater 14aa as a heat source. Overheating roller 1
4a consists of a silicone rubber roller or a Teflon roller. The pressure roller 14b is pressed against the heating roller 14a at a predetermined pressure by the elasticity of a spring (not shown). A thermistor, a temperature fuse, etc. connected to a temperature control means (not shown) are arranged around the heating roller 14a surrounded by the unit casings 14c and 14d, and the temperature of the means 14 is controlled. . Furthermore, a release agent coating felt 14ab and a separation claw 14ac are in contact with the circumferential surface of the heating roller 14a. The heating means 14 heats and fixes the toner image after excess solvent has been removed by the solvent removing means 13A.

[0006] Now, let us look at the form of the toner image from the time it is separated from the photoreceptor drum 1 until it is fixed. The unfixed toner image T1 immediately after the transfer and before passing through the solvent removing means 13A is transferred to the transfer paper P as shown in FIG. 17(a).
is present in the solvent D on the image bearing surface of the image bearing surface. In this case, if the cohesive force of the toner particles forming the unfixed toner image T1 is weakened due to deterioration of the developer over time or a decrease in the amount of charge due to environmental changes, the cohesive force between the toner particles and the transfer paper P may be weakened. There are also partially suspended toner particles due to the low binding force. The unfixed toner image in such a state is removed by the solvent removing means 1.
3A, as shown in FIG. 17(b), the toner image T3 is crushed when it is pressed by the blotter roller 13a and the backup roller 13b, and when this image is sent to the heating means 14, As shown in FIG. 17(e), a flowing toner image T6 is formed, resulting in an image of poor quality. Unfixed toner image T shown in FIG. 17(c)
5 shows a toner image that was not crushed by the solvent removing means 13A.

[0007] In order to avoid image blurring in the solvent removal section and subsequent steps, a method has been proposed that takes measures to increase the cohesive force of deteriorated toner. For example, in FIG. 18, a positive high voltage having a polarity opposite to that of the toner is applied to the backup roller 13b to increase the cohesive force of the toner particles of the unfixed toner image when the transfer paper passes through the solvent removing means 13A, and to increase the A configuration that removes the solvent is also conceivable. Also,
If the cohesive force of the toner particles is electrically increased before the solvent removal step, as shown in the toner image T2 shown in FIG. 17(aa), the unfixed toner image after the solvent removal will be c.
) is not crushed as shown by reference numeral T4, and when it is sent to the heating means 14, it is fixed as a non-flowing toner image T5, as shown in FIG.

[0008]

[Problems to be Solved by the Invention] By the way, in transfer papers with low hygroscopicity such as OHP sheets and art paper, the influence of image washing cannot be ignored, so excess solvent is removed from the transfer paper after toner image transfer. Furthermore, by applying a high voltage charge of opposite polarity to the unfixed toner image to the unfixed toner image, its cohesive force is increased and its adhesion to the transfer paper is increased, thereby preventing image washing. However, when a transfer paper with good hygroscopicity or a highly conductive transfer paper such as carbon paper is used, there is a risk that the transfer paper will overheat due to the application of a high potential.

[0009] Therefore, an object of the present invention is to avoid the above-mentioned danger and improve the toner image by controlling the operation of applying a potential to promote adhesion between the toner and the transfer paper in accordance with the characteristics of the transfer paper used. An object of the present invention is to provide a fixing preprocessing device for a copying machine that can prevent the flow of images and obtain good image quality.

0010

[Means for Solving the Problems] An object of the present invention is to convert an electrostatic latent image formed on an electrostatic latent image carrier into a toner image using a liquid developer, and to transfer the obtained toner image to a transfer paper. In a wet development transfer type copying machine that fixes the toner image by heating the toner image using a heating means that is in contact with the toner image bearing surface of the transfer paper, the toner image is transferred and then sent to the heating means. a potential applying means that is provided in the conveying path of the transfer paper and applies a potential of opposite polarity to the toner to at least the back surface of the transfer paper carrying the toner image; a characteristic measuring means disposed on the transfer path of the transfer paper before being transferred, and measuring the characteristics of the transfer paper; and an operation of the potential applying means according to the characteristics of the transfer paper measured by the characteristic measuring means. This is achieved by a fixing pre-processing device for a copying machine characterized by comprising a control means for controlling.

[0011]

[Operation] According to the copying operation, a toner image is formed on the electrostatic latent image carrier, and the transfer paper is sent out in synchronization with this. At a position before the toner image is transferred, the transfer paper is measured for its resistance value, smoothness, and other characteristics, and the results are input to the control means. The means for applying a potential to the unfixed toner image is controlled by a control means as to whether or not to apply the potential, depending on the characteristics of the transfer paper.

0012

EXAMPLES The present invention will be explained in detail below. In the following description, components equivalent to those of the prior art shown in FIG. 18 will be given the same reference numerals, and detailed description thereof will be omitted.

In FIG. 1, a characteristic measuring means 18 for measuring the characteristics of the transfer paper P is provided in the transfer paper conveyance path 11 between the paper feeder 6 and the registration rollers 12. In the transfer paper conveyance path 17 between the separation roller 8 and the heating means 14,
A fixing pretreatment device main body 13 including a potential applying means to be described later is provided. Furthermore, a control means 19 consisting of a computer is provided at a suitable location in the main body of the copying machine to control the operation of the fixing pretreatment device main body 13 according to the characteristics of the transfer paper inputted from the characteristic measuring means 18. These fixing pretreatment device main body 13, characteristic measuring means 18, and control means 1
9 constitutes a fixing pretreatment device.

The means for measuring the characteristics of the transfer paper include both a resistance value measuring means 18A for measuring the resistance value of the transfer paper and a smoothness measuring means 18B for measuring the smoothness of the toner image bearing surface of the transfer paper. Alternatively, it is sufficient if it is composed of either one of them. However, if priority is given to preventing overheating of the transfer paper from the viewpoint of safety, at least the resistance value measuring means 18A shall be provided.

Referring to FIG. 2, an example of the resistance value measuring means 18A will be explained. Measuring rollers 180 and 181, which are conductive rollers capable of holding the transfer paper P stopped at the registration position in the thickness direction thereof, are disposed in the transfer paper conveyance path 11 upstream of the registration rollers 12. These rollers 1
80 and 181 are pressed against each other to the extent that they do not interfere with conveyance of the transfer paper, and are rotatably supported by an immovable side plate 183 via an insulating bearing 182. Measuring roller 181
is connected to one input terminal of a comparator 184 of a resistance value measuring circuit via a conductive shaft and a brush, and the measuring roller 180 is grounded via a conductive shaft and a brush. A reference value is applied to the other input terminal of the comparator 184 via a register R. The comparator 184 inverts its output when the resistance value of the transfer paper P is higher than the reference value, for example in the case of a transfer paper exhibiting high resistance such as art paper, so that the characteristic of the transfer paper is high resistance. Outputs a measurement signal indicating this. If the resistance value of the transfer paper is lower than the reference value, such as carbon paper, the output of the comparator is not inverted and a measurement signal indicating that the transfer paper has low resistance is output. The output terminal of the comparator 184 is connected to the control means 19.

3 and 5, the smoothness measuring means 18
An example of B will be explained. In the transfer paper transport path 11 upstream from the registration rollers 12, a light emitting element 18 emits light at an angle toward the surface of the transfer paper P stopped at the registration position.
5, and a light receiving element 186 which is arranged offset from the optical axis of the light emitting element and which emits a signal when it receives light that is diffusely reflected depending on the smoothness of the surface of the transfer paper P. The output of the light receiving element 186 is connected to one input terminal of a comparator 187, and a predetermined value is input to the other input terminal of the comparator. When the output of the light-receiving element 186 is lower than a predetermined value, that is, when the surface of the transfer paper P is smooth, the output of the comparator 187 is inverted and output, and upon receiving this, the control means 19 turns on the high-voltage power supply. Outputs a signal to

Referring to FIG. 6, an example of the fixing pretreatment device main body 13 will be explained. The transfer path 17 of the transfer paper P separated from the photosensitive drum 1 by the separation roller 8 and carrying the untransferred toner image T1 includes a blotter roller 30 that contacts the toner image carrying surface of the transfer paper, and a blotter roller 30 that contacts the blotter roller 30. A backup roller 31 made of a conductive material and a high voltage power source V for supplying a positive bias voltage to the backup roller 31 are provided. It is assumed that the toner is negatively charged. The blotter roller 30 has a conductive roller as a core metal and a thick, liquid-absorbing solvent absorber is formed around the core metal, and is grounded via the core metal to connect to the counter electrode. It has the function of A switch S is provided between the high voltage power supply V and the backup roller 31. This switch S is selectively turned on according to the measurement result of the characteristic measuring means 18 when the transfer paper P passes between both rollers. In this example, the rollers 30, 31 and the high-voltage power supply V constitute a potential applying means, which also serves as a solvent removing means. In FIG. 6, reference numeral 32 indicates the backup roller 3
1 shows a cleaning pad for cleaning the circumferential surface of 1. The operation of the fixing pretreatment device main body 13 and its results will be described later.

The operation of the embodiment configured as above will be explained with reference to FIGS. 1 and 4. Since the copying process has been explained in the section of the prior art, the process after the transfer paper P is fed will be explained. A toner image is formed on the photoreceptor drum 1, and a paper feeder 6 is used to transfer the toner image.
A selected transfer sheet P is sent out to a conveyance path 11, and is temporarily stopped by a registration roller 12 in order to synchronize with the image. The rotation of the registration roller 11 is controlled by a registration clutch operated by a registration sensor (not shown) that detects transfer paper. When the registration clutch is not “ON”, that is, the registration roller 1
When the transfer paper P is stopped at step 1, the control means 19:
When the high voltage power supply V (see Fig. 6) is turned off and the registration sensor detects the transfer paper, the comparators 184 and 187
Check the output of , and if either one is "ON", set the high voltage flag to "ON" and return. Also,
When starting the transfer paper P, that is, when the registration clutch is turned "ON", check the high pressure flag, and if it is "ON", the fixing pretreatment device main body 1
3, the high-voltage power supply V is turned on, and a potential is applied between the blotter roller 30 and the backup roller 31. The application time of this potential is controlled according to the size of the transfer paper. When checking the output of the comparator, if there is no output, the high voltage flag is turned OFF and the process returns. The output of the comparator may be a case where the transfer paper P has a high resistance value or a case where the transfer paper P has a high smoothness such as an OHP sheet or a second original drawing paper.

When a transfer paper with a low resistance value such as carbon paper is used, as shown in FIG. 2, when the registration roller 12 is stopped (the registration sensor is on in FIG. 4), the measurement roller 180, When the resistance value is measured at 181, the comparator 184 compares it with the reference value.
Since there is no output, turn off the high pressure flag. The transfer paper made of carbon paper is re-fed in synchronization with the photoreceptor drum 1 (in Fig. 4, the resist clutch is set to "ON").
), the high voltage flag is off at this time, so the high voltage power supply is kept off. On the other hand, the re-fed transfer paper P is
In FIG. 1, the photosensitive drum 1 is conveyed so as to be in close contact with the circumferential surface of the photosensitive drum 1, and a transfer corona is applied from the back surface of the photosensitive drum 1 by a transfer charger 7 to transfer the toner image on the drum. The transfer paper P to which the toner image T1 has been transferred is transferred to the separation roller 8
The paper is separated from the drum circumferential surface by , and is guided to a transfer paper conveyance path 17 and conveyed toward a fixing pre-processing device 13 as shown in FIG. 6 . The unfixed toner image T1 when sent to this preprocessing device 13 is as shown in FIG. 17(a) or (a).
As shown in a), it exists in the solvent film of the liquid developer. The transfer paper P carrying the unfixed toner image T1 is transferred to the blotter roller 30 and the backup roller 31.
When the toner image is pinched and sent to the blotter roller 30, the excess solvent D is removed from the toner image brought into contact with the blotter roller 30, as shown in an unfixed toner image T4 shown in FIG. 17(c). The transfer paper from which the solvent has been removed is sent to the heating means 14, and the unfixed toner image T4 is brought into direct contact with the heating roller 14a, heated, and fixed as a toner image T5 before being sent out of the machine.

That is, in the case of a low-resistance transfer paper such as carbon paper, the fixing pretreatment device main body 13 only performs the operation of removing the excess solvent D from the transfer paper P passing through it.

Next, the effect when a material having high resistance and high smoothness, such as an OHP sheet or art paper, is used as a transfer paper will be explained. In FIG. 1, a toner image is formed on a photoreceptor drum 1, and a transfer paper P made of art paper, for example, is fed from a paper feeder 6 to a conveyance path 11 to be transferred with the toner image, and is synchronized with the image. Therefore, it is temporarily stopped by the registration roller 12. In FIG. 4, the rotation of the registration roller 11 is controlled by a registration clutch operated by a registration sensor (not shown) that detects transfer paper. When the registration clutch is not "ON", that is, when the transfer paper P is stopped by the registration rollers 11, the control means 19 first turns on the high voltage power supply V (
(see FIG. 6) is turned off and the registration sensor detects the transfer paper, the outputs of the comparators 184 and 187 are checked. Since art paper has a high resistance value, the comparator 184 in FIG. 2 outputs an inverted signal and inputs this signal to the control means 19. On the other hand, the light emitted from the light emitting element 185 shown in FIG. 3 is substantially totally reflected due to the high smoothness of the art paper and does not enter the light receiving element 186, and is inverted and outputted by the comparator 187 shown in FIG.

Therefore, in FIG. 4, since the output of the comparator is "ON", the high voltage flag is set to "ON" and the process returns. Then, when starting the transfer paper P, that is, when the registration clutch is turned "ON", check the high pressure flag and confirm that it is "ON".
If so, close the switch S of the fixing pretreatment device main body 13, turn on the high voltage power supply V, apply a positive potential opposite to the negative polarity of the toner to the backup roller 31, and create an electric field between it and the blotter roller 30. Form. The timing for turning on the high voltage power supply V may be just before the leading edge of the transfer paper P enters the fixing pretreatment device main body 13 in FIG. Further, the potential application time is controlled according to the transfer paper size detected by a registration sensor or the like. On the other hand, the re-fed transfer paper P
In FIG. 1, the photosensitive drum 1 is conveyed so as to be in close contact with the peripheral surface of the photosensitive drum 1, and a transfer corona is applied from the back surface of the photosensitive drum 1 by a transfer charger 7 to transfer the toner image on the drum. The transfer paper P onto which the toner image T1 has been transferred is separated from the drum circumferential surface by the separation roller 8, guided to the transfer paper conveyance path 17 as shown in FIG.
It is transported towards 3.

Hereinafter, the transfer paper P made of art paper is subjected to solvent removal and toner image adhesion processing by the fixing pretreatment device main body 13 and fixing processing by the heating means 14 before being discharged, so that the transfer paper P is changed for each processing. This will be explained while looking at the form of the toner image. As shown in FIGS. 17(a) and (aa), the unfixed toner image T1 at a stage before being transferred to the transfer paper P and undergoing pretreatment for fixing has a strong adhesion force with the transfer paper within the solvent film. Exists in a small state. The form shown in Figure (a) often appears in art paper, etc., which has poor hygroscopicity. When the transfer paper P carrying the unfixed toner image T1 is held between the blotter roller 30 and the backup roller 31,
Excess solvent D on the toner image bearing surface is removed, and
The toner particles forming the unfixed toner image are attracted to the transfer paper P according to the electric field formed between the blotter roller 30 and the backup roller 31, as shown in FIG. 17(c).
As shown in the unfixed toner image T4 shown in FIG. The transfer paper P from which the solvent has been removed is sent to the heating means 14, and the unfixed toner image T4 is brought into direct contact with the heating roller 14a and heated.
After being fixed as a toner image T5, it is sent out of the machine.

That is, when the control means 19 determines that the transfer paper is a transfer paper having high smoothness, the control means 19 determines that the transfer paper is a transfer paper with high smoothness.
When the blotter roller 30 is conveyed between the backup roller 31 and the blotter roller 30, the switch S is turned on to form an electric field between the backup roller 31 and the blotter roller 30. In this case, since a bias voltage having a polarity opposite to that of the toner is applied to the backup roller 31, the toner particles in the solvent D can be transferred even if the cohesive force is weak as shown in FIG. 17(a). The particles are attracted to the paper P side and the binding force between the particles and the transfer paper P is strengthened. Therefore, the transfer paper P after the solvent D has been suctioned and removed by the blotter roller 30
The unfixed toner image remaining on the top becomes an unfixed toner image T4 with no image bleeding, as shown in FIG. 17(c). The transfer paper P carrying the untransferred toner image T4 with no image bleeding is fed into the heating means 14, and the heating roller 14a and the pressure roller 1
4b, this unfixed toner image T4 is fixed as an image without image smearing, like a toner image T5 shown in FIG. 17(d).

The unfixed toner image T2 shown in FIG. 17(aa) is a toner image formed with toner of a liquid developer that has not deteriorated and is clumped together by strong cohesive force.

[0026] In the case of transfer paper such as art paper or OHP sheet, which has a smooth image-bearing surface and has low moisture absorption,
Not only the toner image with a weak cohesive force as shown in FIG. 17(a) but also the toner image with a relatively strong cohesive force as shown in FIG. , there is a tendency for the toner image T to be crushed as shown in FIG. 17(b). When such a toner image T is heat-fixed by the heating means 14, it is fixed as an image with image deletion, such as a toner image T6 shown in FIG. 17(e). In this regard, by measuring the characteristics of the transfer paper,
When a potential is applied to the toner image T1 immediately after it has been transferred from the photoreceptor drum 1 to increase its cohesive force and adhesion force to the transfer paper, image flow can be prevented.

The potential applying means shown in FIG. 6 includes a blotter roller 30, a backup roller 31, and a power source V that applies a high voltage to these rollers. Other examples of the potential applying means will be explained with reference to FIGS. 7 to 16. In the following description, the same reference numerals are given to the members already explained.

In the example shown in FIG. 7, the backup roller 31
A positive potential opposite to the negative polarity of the toner from the high-voltage power supply V1 is applied to the blotter roller 30 to attract the toner particles to the transfer paper P side, and a negative potential having the same polarity as the toner is applied to the blotter roller 30 by the high-voltage power supply V2. This is a configuration in which the toner particles are electrically pushed toward the transfer paper P by applying the voltage. Of course, the switches S1 and S2 are controlled by the control means 19.

In the example shown in FIG. 8, the blotter roller 30 as a counter electrode is grounded, and the electrode roller 3
1A and the backup roller 31B are brought into contact with each other to increase the contact length between the transfer paper and the blotter roller, and the electrode roller 3
The configuration is such that a high voltage power supply V is selectively connected to 1A.

The example shown in FIG. 9 has a configuration in which a charger 40 is provided opposite to the grounded blotter roller 30 to which a potential of opposite polarity to the toner image is selectively applied from a high-voltage power source (not shown).

In the example shown in FIG. 10, the blotter roller 30 is grounded as a counter electrode, and the blotter roller 30 is connected to the ground as an electrode at the upstream position of the transfer paper conveyance path of the solvent removing means of the blotter roller 30 and the backup roller 31. A backup roller 31A is provided to perform solvent removal in two stages, and roller pairs 30A and 3 are connected depending on the characteristics of the transfer paper.
The configuration is such that a potential of 1A is applied.

In the example shown in FIG. 11, the blotter roller 30
, the transfer paper guide plates 16 and 17 forming the transfer paper conveying path between the solvent removing means consisting of the backup roller 31 and the separation roller 8 serve as electrodes and counter electrodes. The guide plate 17 is grounded, and the guide plate 1
6 is connected to a high voltage power supply V via a switch S.

In the example shown in FIG. 12, the electrode 16A and the counter electrode 17A, which are independent of the guide plate shown in FIG. This configuration is provided on the upstream side of the pair 30 and 31.

The example shown in FIG. 13 is an example of a fixing pretreatment means that does not have a solvent removing means, and the toner is applied to the transfer paper from the side opposite to the toner image bearing surface of the transfer paper in the transfer paper conveyance path. This configuration includes a charger 40A that applies a potential of opposite polarity.

In the example shown in FIG. 14, a charger 40A of the first potential application means and a second potential application means are placed in the transfer paper transport path 17 upstream of the solvent removing means consisting of the blotter roller 30 and the backup roller 31. charger 40B
This is a configuration with a Charger 40A is high voltage power supply V1
The charger 40B applies a potential of the opposite polarity to the toner of the high voltage power supply V2, and the charger 40B applies a potential of the same polarity to the toner of the high voltage power supply V2.

The example shown in FIG. 15 has the structure of the example shown in FIG. 14 except that the solvent removing means (30, 31) is removed.

In the example shown in FIG. 16, the backup roller that comes into contact with the blotter roller 30 is composed of a hollow roller 31C made of an insulating material, a cleaning blade 32A is pressed against the outer peripheral surface of the roller 31C, and a charger 40 is installed inside the roller.
This is a configuration in which A and 40C are provided. Charger 40A is
The charger 40C is supplied with a potential of opposite polarity to the toner from a high-voltage power source (not shown) and applies a potential between the blotter rollers to strengthen the adhesion of the toner to the transfer paper. It promotes toner separation from the outer peripheral surface, improves the cleaning performance of the backup roller, maintains bias application performance, and prevents staining on the back of the transfer paper.

FIG. 7 shows potential applying means in the present invention.
Any of the examples shown in FIGS. 16 to 16 may be used.

[0039]

As described above, according to the present invention, which controls the application of potential to an unfixed toner image according to the characteristics such as smoothness and resistance value of the transfer paper, it is possible to use a transfer paper with a smooth toner image bearing surface. It is possible to prevent image blurring and obtain a good image, and to avoid the risk of overheating in low-resistance transfer paper.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a wet-type copying machine equipped with a fixing pretreatment device of the present invention.

FIG. 2 is a side view showing an example of a resistance value measuring means as a characteristic measuring means and its circuit.

FIG. 3 is a side view showing an example of smoothness measuring means as a characteristic measuring means.

FIG. 4 is a flowchart showing the operation of the control means based on the characteristic measuring means.

FIG. 5 is a circuit diagram of smoothness measuring means.

FIG. 6 is a front sectional view showing an example of a potential applying means and a heating means.

FIG. 7 is a front sectional view showing different examples of potential applying means.

FIG. 8 is a front sectional view showing still another example of the potential applying means.

FIG. 9 is a front sectional view showing still another example of the potential applying means.

FIG. 10 is a front sectional view showing still another example of the potential applying means.

FIG. 11 is a front sectional view showing still another example of the potential applying means.

FIG. 12 is a front sectional view showing still another example of the potential applying means.

FIG. 13 is a front sectional view showing still another example of the potential applying means.

FIG. 14 is a front sectional view showing still another example of the potential applying means.

FIG. 15 is a front sectional view showing still another example of the potential applying means.

FIG. 16 is a front sectional view showing still another example of the potential applying means.

FIG. 17 shows unfixed toner images before and after pre-fixing treatment;
FIG. 3 is an enlarged view showing the form of a toner image after a fixing process.

FIG. 18 is a front sectional view showing an example of a conventional fixing pretreatment device.

[Explanation of symbols] 1... Photosensitive drum 5... Wet type developing device 6... Paper feeding device 7... Transfer charger 8... Separation roller 11... Transfer paper conveyance path 12... Registration roller 13...Fixing pre-processing device body 13a...Blotter roller 13b...Backup roller 17...Transfer paper conveyance path 18...Characteristics measuring means 18A...Resistance value measuring means 18B... Smoothness measuring means 19... Control means V... High voltage power supply S... Switches T1, T2, T3... Unfixed toner images T5, T6...
・Fixed toner image

Claims (3)

[Claims] Claim 1: The electrostatic latent image formed on the electrostatic latent image carrier is converted into a toner image using a liquid developer, the obtained toner image is transferred to a transfer paper, and the toner image carrying surface of the transfer paper is In a wet development transfer type copying machine that fixes the toner image by heating the toner image using a heating means that is brought into contact with the toner image, a copying machine is provided in a conveying path of the transfer paper after the toner image is transferred until it is sent to the heating means. a potential applying means for applying a potential of opposite polarity to the toner to at least the back side of the transfer paper carrying the toner image, and transporting the transfer paper before the toner image is transferred from the electrostatic latent image carrier. The method further comprises: a characteristic measuring means disposed in the transfer paper path for measuring the characteristics of the transfer paper; and a control means for controlling the operation of the potential applying means according to the properties of the transfer paper measured by the characteristic measuring means. Characteristics of the fusing pre-processing device for copying machines. 2. The fixing pretreatment device for a copying machine according to claim 1, wherein the transfer paper characteristic measuring means includes means for measuring a resistance value of the transfer paper. 3. The fixing pretreatment device for a copying machine according to claim 1, wherein the transfer paper characteristic measuring means includes means for measuring the smoothness of the transfer paper.