JPH03180879A - Image forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Fig. 6) Means for solving the problems to be solved by the invention (Fig. 1) Working examples (al 1) Description of the embodiment (Fig. 2) (b) Description of the second embodiment (Fig. 3) (e) Description of the third embodiment (Figs. 4 and 5) (d) Other implementations Explanation of Examples Effects of the Invention [1 Already Required] Regarding an image forming device that transfers an image formed on an image carrier to a transfer medium by a transfer roller, the structure of the conveyance system is simplified, and the device is made smaller and lower in price. The purpose is to realize the following: an image carrier, an image forming section that forms an image on the image carrier, a take-out section that takes out a transfer medium from a hopper, and a system that transfers the image on the image carrier to the transfer medium. The taken-out transfer medium is abutted against the transfer roller, is wound around the transfer roller, and the transfer medium is conveyed by the transfer roller and transferred.

[Industrial application field]

The present invention relates to an image forming apparatus that transfers an image formed on an image carrier to a transfer medium using a transfer roller.

In image forming devices such as electrophotographic devices and transfer-type electrostatic recording devices, a transfer device is provided to transfer a toner image or latent image formed on an image bearing member such as a photosensitive drum or a dielectric drum to a transfer medium. ing.

As this transfer device, a transfer roller, which has higher transfer efficiency than a transfer charger, is attracting attention, and it is desired to use a transfer roller to simplify the device configuration.

[Conventional technology]

FIG. 6 is an explanatory diagram of the prior art.

An image forming apparatus, such as an electrophotographic apparatus, is configured as follows.

After the rotating photosensitive drum 10 is pre-charged by a pre-charger 11, it is exposed to light by an image writing section 12 to form an electrostatic latent image.

The electrostatic latent image on the photosensitive drum 10 is developed by a developing device 13 to form a toner image.

On the other hand, the paper is taken out from the hopper 20 by the big roller 21, hits registration rollers 22a and 22b, and waits.

The paper being taken out by the big roller 21 and waiting is detected by the paper position detection sensor 23.

The paper is conveyed from the registration rollers 22a and 22b in synchronization with the toner image on the photosensitive drum IO, and the pressing is performed by the roller 24.
The paper is guided to the photosensitive drum 10 by the transfer roller 14.
The toner image is transferred to the paper.

The paper is further sent to the fixing section 3, where the toner image is fixed by a pressure roller 30 and a fixing roller 31.

On the other hand, after the transfer, the photosensitive drum 10 is cleaned by a cleaner 15 in preparation for the next image forming cycle.

Incidentally, in order to clean the photosensitive drum 1 from static electricity, some devices use a static eliminator such as a static eliminator lamp to remove static electricity.

The transfer roller 14 is configured to supply a transfer bias voltage to a conductive or dielectric roller, and is applied with a spring or the like in order to press the photosensitive drum 10 with an appropriate pressure.

In an image forming apparatus using such cut paper, a paper as a transfer medium is pulled out from a hopper 20 by a pick roller 21, and a paper position detection sensor (pick sensor) 2
Prepare in position 3.

The pair of rollers in this position is called a registration roller 22.

Next, a feed roller (not shown) is a roller that has the function of feeding the paper toward the transfer section, and as shown in FIG. 6, it often also serves as the registration roller 22.

When the transfer medium reaches the vicinity of the transfer section, it is necessary to press it against the photosensitive drum 10 before entering the transfer section or during transfer, in order to ensure stable conveyance at the transfer section.

A roller having this function is called a pressing roller 24.

As described above, the conventional image forming apparatus requires at least two rollers: the registration roller 22 having the role of registration and feeding, and the pressing roller having the pressing function.

[Problem to be solved by the invention]

However, the conventional technology requires various rollers to convey the cut medium, resulting in a complicated configuration, which makes it difficult to downsize the device and also makes it difficult to reduce the cost. there were.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming apparatus that can simplify the configuration of a conveyance system and realize miniaturization and cost reduction of the apparatus.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the present invention.

As shown in FIG. 1, the present invention includes an image carrier 10, an image forming section 1 that forms an image on the image carrier 1O, a take-out section 21 that takes out a transfer medium from a hopper 20, and a It has a transfer roller 14 that transfers the image on the image carrier 10, and the taken-out transfer medium is abutted against the transfer roller 14 and wound around the transfer roller 14, so that the transfer medium is transferred to the transfer roller 14. The image is transferred by conveying the image.

[Effect]

In the present invention, the transfer roller 14 has a function of pressing the transfer medium against the image carrier 10 in the transfer section, and this is also utilized for pressing and conveying the transfer medium. By abutting against each other, it also functions as a registration roller.

As a result, the transfer roller 14 serves as a registration roller, a feed roller, and a pressing roller.
These rollers are no longer necessary, the number of parts is greatly reduced, the device configuration can be simplified, and the device can be made smaller and lower in price.

〔Example〕

(a) Description of the first embodiment FIG. 2 is a block diagram of a first embodiment of the present invention.

In the figure, the same parts as shown in Figures 1 and 6 are:
They are indicated by the same symbols, and 25 is a guide roller.
A paper guide 26 is provided near the pick sensor 23 and facing the transfer roller 14, and guides the paper that is wrapped around the transfer roller 14 and conveyed.

Note that the pre-charger 11, the image writing section 2, and the developing device 13 correspond to the image forming section 1.

In this embodiment, the transfer roller 14 is constituted by a roller having a large diameter that is the same as the diameter of the photosensitive drum 10, and is driven to rotate in synchronization with the photosensitive drum 10 by a rotation source (not shown).

Further, the hopper 20 and the pick roller 21 are provided at the bottom and are provided close to the transfer roller 14.

To explain the operation of this embodiment, in response to a print start instruction from a control unit (not shown), the big roller 21 is operated, the paper is pulled out from the hopper (paper cassette) 20, and the leading edge of the paper is connected to the transfer roller 14 and the guide. The paper reaches the engagement portion of the roller 25 and hits the transfer roller 14.

The pick sensor 23 detects this and notifies the control section of the main body of the apparatus that the paper is ready to be transported.

According to instructions from the control unit, after a certain period of time, the photosensitive drum 10
and the transfer roller 14 and guide roller 25 rotate at the same time,
The paper is conveyed to the transfer section.

At this time, if voltage is applied to the transfer roller 14, the paper is electrostatically attracted to the transfer roller 14, and the transfer roller 14
4 and is transported in a wrapped form.

This electrostatic adsorption force is small and unstable, and is easily affected by the environment, so a paper guide 26 is provided to guide the paper to prevent unnecessary trouble.

Meanwhile, as the photosensitive drum 10 rotates, the pre-charger 11 is turned on, the image writing section 12 starts exposing the photoimage, and the developing device 13 also starts a developing operation to form a toner image on the photosensitive drum 10.

The paper that has reached the transfer section exits from the paper guide 26 and simultaneously enters the transfer section, that is, the engagement portion between the transfer roller 14 and the photoreceptor 10.

At this time, when a voltage that satisfies the optimum transfer conditions is applied to the transfer roller 14, the paper is pressed against the photosensitive drum 10 and receives the toner image transfer.

After the transfer, the paper is conveyed toward the fixing section 3 and is fixed by the pressure roller 30 and fixing roller 31 of the fixing section 3.

In this way, the three operations that were required of rollers in conventional paper conveyance systems, namely registration, feeding, and pressing, have been reduced to one.
This is realized by two transfer rollers 14 (more precisely, the transfer roller 14 and the guide roller 25).

The reason why this transfer roller 14 has a larger diameter than the conventional one is as follows.

In this embodiment, no gap (dimensional gap) is provided between the transfer roller 14 and the photosensitive drum 10.

Therefore, the transfer roller 14 and the photosensitive drum 10 should rotate at the same linear velocity.

When uniform charging by the pre-charger 11 is started and a so-called image forming process is started, the photosensitive drum 10 naturally starts to rotate, and the transfer roller 14 starts to rotate as well.

If the transfer roller 14 is required to function as a conveying roller as in the present invention, the toner image on the photosensitive drum 10 must reach the transfer section after the leading edge of the paper reaches the transfer section. As a result, a distance must be obtained on the transfer roller 14 that is longer than the distance (circumference) on the photosensitive drum 10 from the transfer section to the image information exposure section 12.

Therefore, in this embodiment, a large-diameter transfer roller 14 having the same diameter as the photosensitive drum 10 is used, the distance from the transfer section to the image writing section 12 is 120'', and the distance from the transfer section to the registration section (guide roller
5) is 180".

As a result, the paper is transferred between the transfer roller 14 and the guide roller 2.
It is only necessary to start exposing (writing) the image information after the photosensitive drum 10 has rotated more than 60 @ after the photosensitive drum 10 starts to be conveyed by the photosensitive drum 10 during this period.
Uniform charging above 0 is stable and sufficient preparation for image formation is achieved.

In addition, in this embodiment, paper loading and exit can be performed from the same side of the apparatus, improving operability.

Furthermore, since the diameter of the transfer roller is made large, the degree of contamination of the transfer roller 14 due to toner and paper powder can be kept small relative to the number of sheets printed.

Note that the bracket and spring for applying pressure to the transfer roller 14 against the photosensitive drum IO are omitted in the figure.

(bl　Description of the second embodiment FIG. 3 is a block diagram of a second embodiment of the present invention.

In the figure, the same parts as those shown in FIGS. 1, 2, and 6 are indicated by the same symbols, and 27 is a paper guide plate, which is installed between the transfer section and the fixing device 3. , which guides the paper after transfer.

The example in FIG. 3A shows an example in which the diameter of the photosensitive drum 10 is small due to miniaturization, and the diameter of the transfer drum 14 is such that if the curvature is large, it will impede smooth conveyance of the paper.
Can't make it smaller.

In this example as well, in order to cause the toner image on the photosensitive drum 10 to reach the transfer section after the leading edge of the paper reaches the transfer section, the distance from the transfer section to the image writing section 12 is 1600, and the distance from the transfer section to the registration section is 1600. It is set at 1800.

Further, in the example shown in FIG. 3(B), the diameter of the transfer roller 14 is made smaller than the photosensitive drum 10 in order to further reduce the size.

In this example as well, in order to cause the toner image on the photosensitive drum IO to reach the transfer section after the leading edge of the paper reaches the transfer section, the distance from the transfer section to the registration section is set at about 210 degrees, which is 1806 degrees or more.

Conversely, the distance from the transfer section to the image writing section 12 may be about 100', which is less than 120''.

(C) Description of the third embodiment FIG. 4 is a block diagram of a third embodiment of the present invention.

In the figure, the same parts as those shown in FIGS. 1, 2, 3, and 6 are indicated by the same symbols, and 4 is a control unit, such as a microprocessor (MPU). configured,
Operation control of the front charger 11, image writing section 12, developing device 13, pick roller 21, photosensitive drum 10, transfer roller 14
5 is a separation mechanism that controls the rotation of the transfer roller 14, a guide roller 25, a paper guide 26, and a separation mechanism 5 that will be described later. 28 is a paper sensor for moving the guide plate 27 toward and away from the photosensitive drum IO;
This is to detect the end of the paper sent to the fixing device 3.

In this embodiment, a separating/separating mechanism 5 is provided to separate the transfer roller 14 from the photosensitive drum 10 except when necessary.
contact with the photosensitive drum 1 while there is no paper between the
This prevents stains caused by toner from scratch and prevents stains on the back side of the paper.

FIG. 4 is a processing flow diagram of a third embodiment of the present invention.

■ When the control unit (MPU) 4 receives a print command from a higher-level controller, it starts printing.

The MPU 4 instructs the big roller 21 to take out (pick) the paper from the hopper 20 .

The MPU 4 checks the detection output of the shock sensor 23, and when the detection output is turned on, it is considered that the shock has been completed.

In this state, the paper is abutted against the transfer roller 14.

(2) The MPU 4 starts the rotation of the transfer roller 4 and the guide roller 25 to start conveying the taken out paper.

The MPU 4 checks whether the scheduled time has arrived at which distance Δ2 has been transported from the start of transport.

Δl is ((distance from the meshing part of the transfer roller 14 to the transfer part) = (distance from the front charger 11 to the transfer part))
It is.

- When the paper is conveyed by Δl by the transfer roller 14, the MPU 4 starts rotating the photosensitive drum 10, then turns on the front charger 11, and starts writing (exposure) in the image writing section 12.
, and the developing device 13 is turned on.

■ The MPU 4 checks whether the scheduled time for the leading edge of the paper to be conveyed to the transfer unit by the transfer roller 14 has arrived, and if the scheduled time has come, the MPU 4 determines that the leading edge of the paper has reached the transfer unit and separates the paper. The mechanism 5 is driven to press the transfer roller 14 into contact with the photosensitive drum IO.

As a result, the toner image on the photosensitive drum 10 is transferred onto the sheet of paper conveyed by the transfer roller 14.

(2) The MPU 4 checks the detection output of the paper sensor 28 and determines whether the trailing edge of the paper has passed the transfer section.

When the MPU 4 determines from the detection output of the paper sensor 28 that the trailing edge of the paper has passed the transfer section, it drives the separation mechanism 5 to separate the transfer roller 14 from the photosensitive drum 10 and release it.

(2) The MPU 4 then stops the rotation of the photosensitive drum 10 and also stops the rotation of the transfer roller 14.

Further, the MPU 4 turns off the pre-charger 11 and turns off the developing device 13, thereby completing printing.

By moving the transfer roller 14 toward and away from the photosensitive drum 10 by the separating mechanism 5 in this manner, the transfer roller 14 does not come into contact with the photosensitive drum 10 except during transfer of paper, so that the transfer roller 14 is not stained with toner. It is possible to prevent this from being transferred to the paper and contaminating the paper.

Further, in this example, the photosensitive drum 10 may be constantly rotated, and even during the initial running operation, the transfer roller 14 can be prevented from becoming dirty.

! d) Description of other embodiments In the above embodiments, the image carrier lO was explained as an example of a photosensitive drum, but it may also be a dielectric drum, and its shape is not limited to a drum, but may also be belt-shaped, etc. Transfer is not limited to toner image transfer, but also includes latent image transfer. It does not exclude.

〔Effect of the invention〕

As explained above, according to the present invention, the transfer roller is given the functions of a registration roller, a feed roller, and a pressing roller, so there is no need for any rollers up to the transfer section, and the number of parts is reduced. This not only has the effect of simplifying the configuration, making the device smaller and cheaper, but also improves the reliability of the device.

[Brief explanation of drawings]

Fig. 1 is a diagram of the principle of the present invention, Fig. 2 is a block diagram of a first embodiment of the present invention, Fig. 3 is a block diagram of a second embodiment of the present invention, and Fig. 4 is a block diagram of a third embodiment of the present invention. FIG. 5 is a diagram illustrating the configuration of an embodiment, FIG. 5 is a processing flow diagram of a third embodiment of the present invention, and FIG. 6 is an explanatory diagram of a conventional technique. - Figure, Image forming section, 0... Image carrier, 4... Transfer roller, O...- Hopper, 1- Taking out section.

Claims (1)

[Claims] An image carrier (10), an image forming section (1) that forms an image on the image carrier (10), and a take-out section (2) that takes out a transfer medium from a hopper (20).
1), and a transfer roller (14) that transfers the image on the image carrier (10) to the transfer medium, the removed transfer medium is abutted against the transfer roller (14), and the transfer is performed. An image forming apparatus characterized in that the transfer medium is wound around a roller (14), and the transfer medium is conveyed and transferred by the transfer roller (14).