JPH02151887A - Picture recorder - Google Patents

Abstract

PURPOSE:To attain high picture recording with a comparatively small power and to simplify a recorder by reversely driving a recording medium and a transfer roller through a power transmitting means by the same motor. CONSTITUTION:By taking advantage of the fact that the direction of power to drive the recording medium 3 is reverse 4to the direction of power by which a transfer roller 91 carries a transfer material 10 at a fixed speed, the same driving source 70 drives the recording medium 3 and the transfer roller 91 through the power transmitting means 74 to reversely rotate them. The power to drive the recording medium 3 and the power by which the transfer roller 91 carries the transfer material 10 at a fixed speed act on the driving shaft of the driving source 70 as reverse load to cancel out. Consequently, the power that the driving source 70 requires becomes smaller, by which high picture quality recording is attainable under the simple structure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image recording apparatus that records an image using toner.

[Conventional technology]

A toner image is formed on a recording medium, and the circumferential speed of the recording medium is made higher than the moving speed of the transfer material to create a gap between the recording medium and the transfer material, and the toner image on the recording medium is transferred onto the transfer material. Transfer techniques are disclosed in JP-A-56-116064 and JP-A-63-2088.

[Problem to be solved by the invention]

It is known that the above method can stably transfer toner on a recording medium onto a transfer material. On the other hand, when recording an image using this transfer method, it is necessary to cause slippage between the recording medium and the transfer material, so the drive source needs a force that balances the frictional force acting between the two.

In addition, in this answer-transfer method, it is known that the larger the pressure force with which the transfer roller presses the transfer material toward the recording medium, the better the image quality becomes.
Along with this, the frictional force acting between the recording medium and the transfer material also increases, and the drive source requires even greater force.

In the conventional example described above, the transfer roller and the recording medium are each driven by independent drive sources, and two motors with considerably large torque are required.

In particular, since the rotation direction of the transfer roller drive motor and the direction of the drive torque are opposite to each other, there is a problem in that the speed is unstable and the quality of recorded images deteriorates.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide an image recording device capable of high-quality recording with a simple structure and a relatively small driving force.

[Means to solve the problem]

The above object is to provide a transfer roller having, around a rod-shaped rigid roller made of a conductive material or an insulating material, an elastic body marker made of a conductive material or an insulating material and having a high friction coefficient with respect to a friction coefficient of a recording medium; A power transmission means having a speed ratio such that the peripheral speed of the recording medium is larger than the peripheral speed of the roller is used, and the transfer roller and the recording medium are transferred by the same driving source via the power transmission means. The roller and the recording medium are driven to rotate in opposite directions, and the transfer material is conveyed at approximately the same speed as the transfer roller circumferential speed, so that the recording medium circumferential speed is greater than the transfer material conveyance speed. This is achieved by causing slippage and transferring the toner on the recording medium onto the transfer material.

[Effect]

When the recording medium is driven, sliding occurs between the recording medium and the transfer material, and a frictional force acts between the two.

This frictional force is transmitted from the transfer material to the transfer roller.

Therefore, in order to convey the transfer material at a constant speed and cause slippage between the recording medium and the transfer material, the transfer roller needs a force that balances the frictional force in the opposite direction to the rotational direction. Therefore, by utilizing the fact that the direction of the force required to drive the recording medium and the force required for the transfer roller to convey the transfer material at a constant speed are opposite, the same drive source can be used via the power transmission means. When the recording medium and transfer roller are driven to rotate in opposite directions, the force required to drive the recording medium and the force required for the transfer roller to convey the transfer material at a constant speed are applied to the drive shaft of the drive source, respectively. They act as loads in opposite directions and cancel each other out. Therefore, the force required for the driving source becomes smaller.

(Example〕 The present invention will be explained below based on the drawings.

FIG. 1 is a cross-sectional view of one embodiment of the present invention.

The recording medium 3 is made up of a conductive layer 31 and an insulating layer 32, and has a cylindrical shape that continues in the direction perpendicular to the paper surface, and its length is such that it can record, for example, A4 size or B size. . 31.0 is a bias voltage applying means that applies a voltage of, for example, about several volts to the conductive layer 31, and in FIG. 1, it is a DC power supply that applies a negative voltage. The recording medium 3 is rotatably installed around its central axis, and is driven at a constant speed in the A direction by a motor 70 that is a driving source. A hole with a diameter of, for example, about 3 to 10 mm is bored in the center of the recording medium 3, and a rod-shaped heater 33 is installed in the hole. This recording medium □ is, for example, aluminum or Af.
After processing the outer peripheral surface of the 1-alloy cylinder, alumite, hard alumite, or porous hard aluminum oxide is impregnated with tetrafluoride resin (Mitsubishi Metals trademark Taflam treatment) to reduce itching. An insulating layer 32 having a thickness of about 10'0 microns is formed.

The electrode 2 is installed at an angle with a gap as shown in the figure with respect to the recording medium 3. Each part of the recording electrode will be explained below. 20 is a substrate made of a nonmagnetic insulator (eg, ceramics or epoxy resin). On this substrate 20, there is a thin line pattern 23 made of a conductor, and a plurality of conductors (preferably magnetic conductors) arranged in a row across the recording width in the direction perpendicular to the plane of the paper on the lower end side of the substrate. Electrode needle 22
A driving IC 21 is provided for applying a certain recording voltage to each of the electrode needles 22 as an electric signal corresponding to an image pattern to be recorded. The terminals of the IC 21 are bonded to the thin line pattern 23 with solder, etc.
is bonded to the electrode needle 22 by a bonding wire 26. The surface of the substrate 20 on the side where the electrode needles are installed, except for the tips of the electrode needles 22, is covered with a protective member 24 made of an insulating non-magnetic material.
covered with. A heat sink 2 is provided on the opposite surface of the substrate 20.
A magnet 5 is provided on the opposite surface of the heat sink 25 from the electrode needle 22, and is provided across the recording width in the direction perpendicular to the plane of the paper.

A suppressing member 15 that engages with a support member 14 fixed to the base of the recording device is provided at the center of the electrode in the recording width direction, so that the pressing member 5 presses the electrode 2.

Reference numeral 11 denotes a hopper which is a container for storing toner, and toner 40 having conductivity and magnetism is stored in the hopper 11 . 120 is a rotating screw for stirring the toner 40 and making the amount of toner uniform over the recording width. 41 is the electrode needle 22 and the insulating layer 32 of the recording medium 3;
The toner is aligned between the 4.2, 421 is toner attached to the recording medium.

A magnetic roll 60 is installed on the outer periphery of the recording medium 3 as a removing means for removing excess toner from the recording medium 3 downstream in the direction of rotation of the recording medium 3 from the installation position of the electrode 2 and downward in the direction of gravity. ing.

This magnetic roll 60 has a sleeve 6 made of non-magnetic material.
00, and is rotatable in the direction B in the figure. The sleeve 600 and the recording medium are installed with a slight gap between them, and an appropriate value for the gap is selected depending on the magnetic properties of the magnetic roll. 601 is a toner receiver.

A first roller is located close to the magnetic roll 6° and the sleeve 600 and conveys the toner from the back of the page to the front in a direction substantially parallel to the recording medium.
A toner conveying means 61 is provided. This first toner conveying means includes a rotating screw 610 and a cover 61.
1 constitutes the main part. Reference numeral 65 denotes a second toner conveying means that conveys the toner to the hopper 11 in the direction of the arrow, approximately at right angles to the first conveying means, and is illustrated as the vibro 51. The main part is composed of a screw 650 that rotates in the E direction by mechanical driving means. The toner cartridge 18 is connected to the lower part of the second toner conveyance means 65 .

This toner cartridge 18 stores toner 47 inside.

A transfer material 10 is conveyed in the direction of arrow F. 130°13
1 is a guide for the transfer material 10. A sensor 19 detects the presence or absence of a transfer material, and the guide 130 is provided with a sensor opening 130a through which the sensor 19 operates. 190 is a sensor output signal processing circuit. 132
is a static elimination brush that removes static electricity from the transfer material, and is installed at an angle along the moving direction of the transfer material 10.

A transfer means 9 for transferring the image toner 43 on the recording medium onto the transfer material 10 is installed on the outer circumference of the recording medium 3 and further downstream from the installation position of the magnetic roll 60 in the direction of movement thereof. This transfer means 9 includes a round bar-shaped rigid roller 910 made of a conductor or an insulator, and a conductor or an insulator.
A transfer roller 91 made of an elastic layer 911 made of an elastic material with a high coefficient of friction, a rotatable bristle brush 92,
It is composed of a bristle brush storage container 93 and a suppression mechanism (not shown) that presses the transfer roller against the recording medium 3. The transfer roller 91 and the recording medium 3 are operated by one motor 70.
They are each driven to rotate in opposite directions via a transfer roller power transmission means 74 and a recording medium power transmission means 75. The motor 70 rotates in the direction of arrow G, and the direction of rotation is changed to the direction of arrow A by gears 75a coaxial with the motor shaft and gear 75b meshing with 75a.

Further, the power transmitted to the gear 75b is transmitted from a timing pulley 75c coaxial with the gear 75b to a timing pulley 75 coaxial with the drive shaft of the recording medium 3 via a timing belt 75d.
e, and the recording medium 3 is driven in the direction of the arrow.

At the same time, the power of the motor 70 is transferred to a timing belt 74 from a timing pulley (not shown) coaxial with the motor shaft.
a to a timing pulley (not shown) coaxial with the friction clutch 72, and the friction clutch 72 rotates in the direction of arrow G.

Further, the power transmitted to the friction clutch 72 is transmitted from a timing pulley 74b coaxial with the friction clutch 72 to a timing pulley 74d coaxial with the transfer roller 91 via a timing belt 74c, and the transfer roller 91 moves in the direction of arrow C. Driven.

94 is a transfer type □ pressure switching circuit, and 700 is a motor drive circuit.

Recording medium 3. Toner 4 remaining on the recording medium is located on the outer circumference of the recording medium and further downstream from the transfer section in the moving direction.
A cleaning means 8 for removing 5 is installed. The cleaning means 8 is a box body 80 that stores the removed toner.
, a cleaning blade 81 attached to the end of the box, a permanent magnet 82, and a toner application electrode 83 that is integrated along the recording width and to which a voltage is constantly applied by a DC power source 85. It is composed of a rotating screw 84.

Next, the operation of the image recording apparatus of the present invention described above will be explained.

The toner cartridge 18 is loaded, and the toner 47 in the cartridge is fed onto the screw 650 of the second toner transport means by the action of gravity.

As the screw 650 rotates in the direction of the arrow E within the vibro 51, the toner 461 is transported by mechanical means from the bottom to the top of the second toner transport means 65 in the direction of the arrow, to the hopper 11. be done.

The toner 40 is conveyed from the front to the back of the paper by the rotating screw 120, and the toner 40 is transported inside the hopper 11.
It is made uniform over the recording width.

The toner 40 in the hopper 11 is supplied to the gap formed by the electrode 2 and the recording medium 3 by the rotation of the recording medium 3 . The gap between the tip of the electrode needle 22 and the recording medium 3 is affected by the static magnetic field of the magnet 5 . The wider the gap, the better in terms of production, but the narrower the better in terms of image quality.
It needs to be uniform over the recording width. Therefore, the warpage of the electrode 2 is corrected by the suppressing member 15.

Due to the static magnetic field action of the magnet 5, the toner 41 contacts both the electrode needle 22 and the surface of the recording medium 3 and is aligned.

The aligned toner 41 is subjected to the rotation action of the recording medium 3 and the toner supply action, and a part of the toner 41 is affected by the rotation of the recording medium 3 and physical adsorption force such as van der Waals force, friction,
The toner weakly adheres to the recording medium 3 due to the electrostatic adhesion force caused by charging, and is carried in the rotational direction of the recording medium, like the toner 421 in the figure.

On the other hand, when a low recording voltage of, for example, about several tens of positive volts is applied to the plurality of electrode needles 22 via the step C21 in accordance with the image signal, toner 41 contacts the electrode needles to which the recording voltage is applied.
A positive charge is injected into.

This positive charge is mainly distributed on the recording medium 3 side. At the same time, negative charges are induced at the boundary between the conductive layer 31 and the insulating layer 32 of the recording member 3. Therefore, the toner group injected with electric charge strongly adheres to the recording medium 3 due to the electric force, and receives the rotational action of the recording medium 3 and the toner supply action, and as shown in the toner 42 in the figure, the toner group adheres strongly to the recording medium 3 due to the electric force. It is carried to.

At this time, toner is immediately supplied from the upstream side in the recording medium movement direction, the aligned toner 41 is immediately re-formed, and the shape of the aligned toner 41 and the position in contact with the recording medium 3 are kept substantially constant. This dynamically stable and aligned toner 41 allows the toner to adhere to the recording medium.
A toner image can be stably formed on a recording medium at high speed.

Among the toners attached to the recording medium 3, the weakly attached toner 421 is selectively and easily removed from the recording medium 3 by the centrifugal force 2 due to the rotation of the recording medium 3 or by the magnetic attraction force of the magnetic roll 60. can do. Therefore, after the toner image on the recording medium 3 passes through the magnetic roll 60 serving as a removing means, the toner image on the recording medium 3 is removed by the weakly attached toner 4.
21 is removed onto the magnetic roll and the toner 4 strongly adhered
3 to form a developed image. On the other hand, the removed toner 421 is conveyed in the C direction by the rotation of the magnetic roller, is sent onto the screw 610, and is conveyed along with the toner supplied from the toner cartridge to the screw 650.
It is uniformly returned to the hopper 11 through the screw 120 and reused.

As described above, when a recording voltage is applied to the electrode needle 22, the toner 42 that adheres to the recording medium with a strong force causes the developed image 43 to
is formed.

This developed image 43 is transferred onto the transfer material 10 by the transfer means 9 to become a transferred image 44. Transfer image 44 to the transfer material below
The process of forming will be explained.

The recording medium 3 and the transfer roller 91 are driven by the same motor via a recording medium power transmission means 75 and a transfer roller power transmission means 74, respectively. Circumferential speed of recording medium 3 and transfer roller 9
The peripheral speed 1 is a setting in which the peripheral speed of the transfer roller 9'' becomes slower than the peripheral speed of the recording medium 3 via a gear, a timing pulley, or the like.

The friction clutch 72 causes burrs at both ends of the shaft when the transmitted power exceeds a certain value, and is inserted into the transfer roller power transmission means between the motor 70 and the transfer roller 91. While the transfer material 10 is not inserted between the transfer roller 91 and the recording medium 3, the transfer roller 91 directly touches the recording medium 3.
is in contact with and is pressed.

Since the transfer roller 91 has an elastic layer 91 with a high friction coefficient on its surface, a large frictional force is generated between the recording medium 3 and the transfer roller 91, and power is transmitted from the recording medium 3 to the transfer roller 91. Ru. The peripheral speed of the transfer roller 91 is the same as that of the recording medium 3.
Since the peripheral speed is set to be slower than the circumferential speed of It rotates at the same circumferential speed as the medium 3. When the transfer material 10 is inserted between the transfer roller 91 and the recording medium 3, the friction coefficient between the recording medium 3 and the transfer material 10 is very small compared to the friction coefficient between the transfer roller 91 and the transfer material 10, so that the recording is not completed. A large amount of power is not transmitted from the medium 3 to the transfer roller 91, and a gap occurs between the recording medium 3 and the transfer material 10 depending on the set speed difference. Therefore, at the contact point between the recording medium 3 and the transfer material 10, the toner of the developed image 43 on the recording medium 3 is subjected to mechanical peeling force. Since this peeling force is much larger than the electric force that adheres the developed image 43 to the recording medium 3, most of the toner on the recording medium 3 is transferred onto the transfer material 10, and the transferred image 44 and Become.

In addition, a conductive member is used for the rigid roller 910 and the elastic layer 911, and while the transfer material 10 is inserted between the transfer roller 91 and the recording medium 3, the switching circuit 94
When a transfer voltage having a polarity opposite to that of the recording voltage is applied to the transfer roller via the transfer roller, the toner of the developed image 43 receives an electric attraction force toward the transfer material, allowing more efficient transfer.

Due to these mechanical peeling forces and electrical attraction forces, most of the toner in the developed image 43 on the recording medium 3 is transferred onto the transfer material 10 to become a transferred image 44.

At this time, a small amount of toner remaining on the recording medium 3 without being transferred to the transfer material becomes residual toner 45, which is carried by the rotational movement of the recording medium 3 while remaining attached to the recording medium 3. On the other hand, the transferred image 44 is fixed onto the transfer material 10 by a known fixing device (not shown) such as a heat fixing device or a pressure fixing device, and becomes a permanently stored image.

The residual toner 45 remaining on the recording medium without being transferred to the transfer material 10 is removed by the toner applying electrode 83 due to the rotation of the recording medium 3.
transported to the vicinity of The toner application electrode 83 is installed with a slight gap from the recording medium 3. Due to the static magnetic field action of the permanent magnet 83 ↓, the remaining toner collects between the surface of the recording medium 3 and the toner applying electrode 83 . For example, a positive voltage of about several tens of volts is applied to the toner application electrode, and a positive charge is injected into the toner, creating an electrical attraction between it and the charge of opposite polarity induced in the recording medium 3. , re-adheres to the recording medium 3. This redeposited toner 450 moves as the recording medium 3 rotates, is scraped off from the recording medium 3 by a cleaner blade that is pressed against the recording medium 3, and most of it is stored in the box 80. Of the toner scraped off by the cleaner blade, the toner that is not stored in the box 80 and falls between the recording medium 3 and the toner application electrode 83 becomes part of the toner group that collects between the recording medium and the toner application electrode again. , it will not fall onto the transfer material 10 and stain the transfer material. The toner 452 stored in the box body 80 is
The toner is conveyed by the rotation of the toner, collected in a waste toner bottle (not shown), and disposed of.

The time to replace the toner cartridge 18 can be known by, for example, installing a toner sensor (not shown) in the vibro 51 and detecting the amount of toner 461 in the pipe. If the response level of this toner sensor is set to two values, for example, it is possible to first issue a warning and then inform the user of the time to replace the toner.

Next, a flow in which toner adheres to the recording medium 3 and is transferred to the transfer material 10 will be explained.

The toner cartridge 18 is connected to the lower part of the second toner conveying means 65, and the toner is transferred to the hopper 1 by a screw 650.
It is supplied within 1. In this state, the transfer material 10
is conveyed along the guide 130 to the position of the sensor 19, and when the transfer material 10 is detected by the sensor 19, the motor 70 is driven at a predetermined rotation speed via the drive circuit 700, and at the same time, the transfer material 10 is rotated according to the image signal. A recording voltage is applied to the electrode needle 22 and a recording operation begins. At this time, the transfer roller 9
1 is driven at the same circumferential speed as the circumferential speed Va of the recording medium 3 due to the action of the friction clutch 72 described above. The sensor 19 is
A position where the time taken for the recording medium 3 to move from the position of the electrode 2 to the point of contact with the transfer roller 91 is equal to the time taken for the transfer material 10 to move from the position of the sensor 19 to the point of contact between the transfer roller 91 and the recording medium 3 It is installed in Therefore, at the same time that the sensor 19 detects the transfer material 10, the motor 70
When the transfer material 10 reaches the point of contact between the transfer roller 91 and the recording medium 3, the leading edge of the developed image 43 on the recording medium 3 is connected to the contact point between the transfer roller 91 and the recording medium 3. The contact point is reached, and recording from the leading edge of the transfer material becomes possible.

When the transfer material 1o is sandwiched between the recording medium 3 and the transfer roller 91, the peripheral speed of the transfer roller 91 becomes the set value Vt (<V, +) due to the action of the friction clutch 72 as described above, and the transfer material 10 It is transported at a speed of Vt. Further, the transfer material 10 reaches the position of the sensor 19, and the sensor 19
When detecting 0, the output signal processing circuit 190 of the sensor 19 with a built-in timer starts counting operation, and the transfer material 10
is sandwiched between the recording medium 3 and the transfer roller 91, and at the same time drives the switching rotation 94, and a voltage of opposite polarity to the recording voltage is applied to the transfer roller 91. The signal processing circuit 190 further continues the counting operation, and just before the transfer material 10 leaves the contact area between the recording medium 3 and the transfer roller 91, it drives the switching circuit 94 and applies the voltage to the transfer roller 91. Turn off the voltage.

During this transfer operation, if a malfunction occurs in which the developed image reaches the transfer roller and toner adheres to the transfer roller 91 even though the transfer material 10 has not reached the transfer roller, the bristle brush 92 will remove the toner from the transfer roller. Since the toner adhering to 91 is removed, the back side of the transfer material will not get dirty.

Furthermore, when the recording medium is rotated, the screw 610°650°
．． 120. The magnetic roll 60 rotates and supplies an appropriate amount of toner to the electric bridge portion.

Further, the heater 33 installed at the center of the recording medium 3 increases the temperature of the recording medium 3 and dehumidifies it in times of high humidity, making it possible to obtain images as good as those in normal humidity even in times of high humidity.

Since the heater is located at the center of the rotating recording medium, the heater 33 itself can be supported without rotating, and the heater 33 can be easily supplied with electricity without using a slip ring or the like.

- After the toner image is transferred from the recording medium 3 by the action of the transfer roller 91, the static elimination brush 132 is moved to the guide 131.
is in contact with the back side of the transfer material before contacting with. Since the static elimination brush 132 is inclined along the moving direction of the transfer material 10, the transfer material 10 smoothly contacts the static elimination brush 132 and is conveyed onto the guide 131. - This static elimination brush 132 can eliminate excess charge from the transfer material 10, especially when the humidity is low, so that the transfer material can be removed from the guide 13 when the humidity is low.
1) The transfer material 10 can be conveyed to the fixing device without being attached by electrostatic force and without disturbing the transferred image 44 on the transfer material 10.

Next, the effects of the present invention in the transfer process in which the developed image 43 on the recording medium 3 is transferred onto the transfer material 10 will be explained in detail. 2 and 3 show the circumferential speed vd of the recording medium 3 and the circumferential speed V of the transfer roller 91 in the image recording apparatus configured in FIG.
FIG. 4 is a diagram showing the results of an experiment regarding the transfer process by changing the speed relationship with t. In FIG. 2, the horizontal axis represents the peripheral speed V of the transfer roller 91 relative to the peripheral speed V of the recording medium 3.

The vertical axis is the transfer efficiency. The transfer efficiency is calculated by dividing the reflection density of the toner 44 transferred onto the transfer material by the reflection density of the toner 43 forming the developed image on the recording medium, and adding 1
Multiply by 00%.

In the experiment, the speed relationship between the circumferential speed Vd of the recording medium 3 and the circumferential speed Vt of the transfer roller 91 was changed, and the transfer roller 91
This was done by changing the pressing force applied to the recording medium 3. FIG. 2 shows this pressing force as a parameter. Second
From the figure, it can be seen that the transfer efficiency is dramatically increased when slippage occurs at a speed ratio of 1 or less, compared to when the speed ratio is 1, where no slippage occurs between the recording medium 3 and the transfer material 91.

It can also be seen that the smaller the speed ratio and the larger the slippage, the higher the transfer efficiency, and the larger the suppressing force, the higher the transfer efficiency. Furthermore, in this transfer means,
When transferring a toner image from the recording medium 3 onto the transfer material 10,
Since the peripheral speed of the transfer roller 91 is set lower than the peripheral speed of the recording medium 3, the toner image 44 on the transfer material 10 shrinks in the conveyance direction of the transfer material 10 and becomes shorter than the toner image 43 on the recording medium. Therefore, the amount of toner per unit area increases, and as shown in FIG. 2, there are cases where the transfer efficiency becomes 100% or more. As described above, from the viewpoint of image density called transfer efficiency, it can be seen that the larger the pressing force is, the better, and the smaller the speed ratio, the better.

On the other hand, when observing the image quality, it was observed that when the speed ratio was 0.8 or less, the image quality was disturbed due to slippage.

FIG. 3 shows the results of an experiment regarding image quality.

The horizontal axis is the ratio of the circumferential speed of the recording medium 3 to the circumferential speed of the transfer roller 91, and the vertical axis is the M, T, and F values, which are one representative index for quantitatively evaluating image quality. Similarly to FIG. 2, FIG. 3 also uses the pressure force with which the transfer roller 91 is pressed against the recording medium 3 as a parameter.

As shown in FIG. 4, M, T, and F are expressed as the reflection density of the reference black area minus the reflection density of the reference peak area, and M,
It is said that the larger the T and F values, the better the image quality. Third
From the figure, M, T, F.

It can be seen that the curves showing the values all have maximum values in the speed ratio range of 0.9 to 0.8, and the image quality is the best in this speed ratio range. In addition, M with a pressing force of 1 kg/■,
M, T, F, with a pressing force of 2 kK/■ compared to the T, F value,
The value increases rapidly, indicating that the higher the pressing force, the better the image quality.

Next, a mechanism for causing slippage between the recording medium 3 and the transfer material 10 will be explained. FIG. 5 is a diagram showing the force relationship when the transfer material 10 is sandwiched between the recording medium 3 and the transfer roller 91. From the results of the experiments described above, it has been found that it is necessary to cause slippage between the recording medium 3 and the transfer material 10 in order to obtain good image quality. Therefore, the motor serving as the driving source needs a force that balances the frictional force F between the recording medium 3 and the transfer material 10. In addition, the transfer roller 9
What is the pressing force N for pressing 1 onto the recording medium 3?

The larger the value, the better the image quality. According to the experiment, recording medium 3
The friction coefficient μ between the transfer roller 91 and the transfer material 10 is approximately 0.2, and the friction coefficient μ2 between the transfer roller 91 and the transfer material 10 is 0.9.
It will be about. Therefore, when the recording medium 3 and the transfer roller 91 move at different speeds, the transfer material 10 moves at the same speed as the transfer roller 91, but slippage occurs between the transfer material 10 and the recording medium 3. If the friction force at this time is F, then F=
μ engineering N...(1). Assuming that the force on the recording medium required for the motor to drive the recording medium 3 is To, and ignoring the loss force due to friction in the recording medium power transmission means 75, in order to drive the recording medium 3 at a constant speed, TD only needs to be the same as the frictional force F. That is, To=F=μIN
...(2). On the other hand, since no slipping occurs between the transfer material 1o and the transfer roller 9'', the frictional force F described above acts as a force that accelerates the transfer material 10. Therefore, the transfer roller 91 requires torque in the opposite direction to counteract this. Therefore, if losses due to friction in the transfer roller force transmission means are ignored, the force TT required on the transfer roller to convey the transfer material at a constant speed is: TT=-F=-μmN...( 3
). The radius of the recording medium 3 is rD, the radius of the transfer roller 91 is rT, and the gear ratio of the recording medium power transmission means is No.
, the gear ratio Nt-r of the transfer roller power transmission means, and the torque TND of the motor required to drive the recording medium 3 at a constant speed is N o N .

The motor torque TNT required to convey the transfer material 91 at a constant speed is N T N 7 . As mentioned above, from the experimental results, the speed ratio α is α=
Approximately 0.15 is good. Therefore, the recording medium 3 and the transfer roller 91 are each driven by independent motors.
of torque is required. As mentioned above, in order to perform high-quality recording, it is necessary to increase the pressing force N, so TMD
, TNT becomes larger and requires two large torque motors. In particular, the drive motor of the transfer roller 91 is
Since the direction of rotation and the direction of the driving torque are opposite,
The drawbacks were that speed stability was poor and recorded image quality deteriorated.

Next, when the recording medium and the transfer roller are driven in opposite directions by the same motor via the power transmission means as in the present invention, the aforementioned drive torques TMD and TNT are applied as loads to the same motor shaft.

Therefore, the torque TM required for the motor at this time is 2
Since it is the sum of the two torques, TM=TMo+TMT=TMD-αTMD ~0.15TMD...(
7), not only one motor is required compared to the conventional invention, but also its driving torque can be reduced to about 1.50%, making it possible to simplify the device.

〔Effect of the invention〕

As explained above, according to the present invention, not only is it possible to record high image quality with a relatively small amount of power, but also it is possible to simplify the apparatus because only one driving source is required.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the present invention, FIGS. 2 and 3 are diagrams showing experimental results related to the present invention, FIG. 4 is a diagram explaining terms in FIG. 3, and FIG. The figure is a diagram showing the relationship of forces acting on the transfer section. 3... Recording medium, 1o... Transfer material, 7o... Motor, 74... Transfer roller power transmission means, 75... Recording medium power transmission means, 91... Transfer roller.

Claims (1)

[Claims] 1. Form an image with toner on a recording medium, supply a transfer material between the recording medium and a transfer roller, and set the circumferential speed of the recording medium higher than the transport speed of the transfer material to form an image with toner on the recording medium. An image recording device that transfers images onto a transfer material includes a rod-shaped rigid roller made of an electrically conductive material or an insulating material, and a rod-shaped rigid roller made of an electrically conductive material or an insulating material that is formed on the outer peripheral surface of the rigid roller and has a coefficient of friction relative to the friction coefficient of the recording medium. A transfer roller constituted by an elastic layer having a high coefficient of friction, and a power transmission means having a speed ratio such that the peripheral speed of the recording medium is large relative to the peripheral speed of the transfer roller, and the power transmission means is the transfer roller and the recording medium are driven by the same drive source so that the transfer roller and the recording medium rotate in opposite directions,
An image recording apparatus characterized in that the transfer material is conveyed at substantially the same speed as the transfer roller circumferential speed, the recording medium circumferential speed is made greater than the transfer material conveyance rate, and the toner on the recording medium is transferred onto the transfer material.