JP2999923B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, and a multifunction machine having a heat roller type fixing device.

[0002]

2. Description of the Related Art At present, many image forming apparatuses employ a heat roller type fixing device including a heat roller having a heater therein and a pressure rubber roller urged to press the heat roller. ing.

The recording paper fixed by the fixing device passes through the fixing device and is discharged to a discharge tray. As a mechanism for discharging the sheet to the discharge tray, a mechanism for sandwiching and transporting the sheet between a pair of sheet discharge rollers is generally used. Is omitted, and the sheet is directly discharged to a sheet discharge tray after passing through the fixing device. For example, Japanese Utility Model Publication No. 4-8429 (G03G 15:00) omits a paper discharge roller that conveys a recording sheet disposed between a fixing device and a paper discharge device, and disposes a fixing device and a paper discharge device in close proximity. The disclosed image forming apparatus is disclosed.

By the way, while the recording paper is sandwiched between the contact portion (hereinafter referred to as a nip portion) between the heat roller and the pressure rubber roller, the recording paper passes due to the frictional resistance of the rubber roller. After the recording paper completely passes through the nip portion, in a device provided with a paper discharge roller, the recording paper is conveyed by the paper discharge roller, the recording paper is discharged to a paper discharge tray, and the paper discharge tray is provided. Stocked on top.

[0005]

However, in a device in which the discharge roller is omitted, there is no mechanism for transporting the recording paper after the recording paper completely passes through the nip portion. Stops.

There is no problem if the recording paper is kicked out of the pressure rubber roller by the frictional resistance between the pressure rubber roller and the recording paper or the force of the paper passing speed, and is discharged to the discharge tray neatly. However, depending on the angle of the output tray, the stock capacity of the output tray, the frame shape of the fixing device, the static electricity of the discharged recording paper, the curl of the discharged recording paper, etc. Stop. As a result, the trailing end of the recording paper remains on the pressure rubber roller, and if the state continues, problems such as paper jam, falling of the recording paper, and stacking failure of the recording paper occur. In addition, since the recording paper discharged to the high-temperature portion remains in contact with the recording paper, a problem such as discoloration of the recording paper to yellow occurs. Further, if the color of the recording paper advances, a fire may occur.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides an image forming apparatus in which a paper discharge roller is omitted, which can reliably discharge recording paper from a fixing device to a paper discharge device. With the goal.

[0008]

According to the present invention, there is provided a fixing device including a heat roller having a heater therein, and a pressure roller urged to press against the heat roller. An image forming apparatus for directly discharging recording paper to be discharged to a paper discharge unit, wherein a flexible member for pressing recording paper discharged from between the two rollers to the pressure roller is provided. Features.

Further, in the present invention, it is preferable that the flexible member is disposed close to a recording paper separating claw that is disposed in contact with the heat roller.

Further, it is preferable that a part or the whole of the flexible member is formed of a material having good releasability from the developing material.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing the internal configuration of a multifunction printer 1 as an image forming apparatus having an analog copy function, a plain paper facsimile function, and a printer function.

A reading unit 2 for reading a facsimile manuscript and a manuscript cover 4 are provided above the multifunction recording apparatus 1.

The reading unit 2 has a reading head (not shown) provided therein. The reading head scans a facsimile document and reads an image. The reading system includes an exposure system for irradiating the document with light and the above-described exposure system. It is composed of a CCD sensor array for receiving light reflected from a document.

The image forming unit (image forming section side) 3
An analog exposure system that optically processes reflected light from a document and guides the light to the photoconductor 17 and a digital exposure system that generates optical information based on a digital signal and irradiates the photoconductor 17 are used.

The analog exposure system includes a platen glass 25
, An optical system including an exposure lamp 12, a lens 13, a mirror 14, and the like arranged below. on the other hand,
The digital exposure system includes a light emitting unit 18 in which pixel-unit LEDs and the like are arranged in a line, and a driving unit (not shown) that drives the light emitting unit 18 based on a digital image signal supplied from a digital signal processing system. It consists of.

Around the photoreceptor 17, a charging charger 19 for uniformly applying a charge to the photoreceptor 17, and a toner (developing material) is formed on the electrostatic latent image formed on the photoreceptor 17 by exposure.
, A transfer charger 20 for transferring a toner image on the photoreceptor 17 to recording paper, a cleaning device 16 for removing residual toner, and the like.

The recording paper on which an image is to be recorded is taken out one by one from a paper feed tray 21 by a paper feed roller 22, timed by a registration roller 23, and between the photoreceptor 17 and the transfer charger 20. Sent in. The recording paper on which the toner image has been transferred by the transfer unit 20a is sent to a fixing unit 30 including a heat roller 31 having a built-in heater and a pressure rubber roller 32. , And the end thereof is kicked out by the pressure rubber roller 32, and the recording paper is stocked on the paper discharge tray 6.

According to the present invention, the fixing unit 30 is improved so that the recording sheet can be reliably discharged from the fixing unit 30 to the discharge tray 6. FIG. 2 is a sectional view showing a fixing section which is a main part of the present invention.

As shown in FIG. 2, the fixing unit 30 of the present invention
Includes a heat roller 31 in which a heater such as a halogen lamp is incorporated, and a pressure rubber roller 32 urged to press against the heat roller 31.
A separation claw 35 for separating the recording paper from the heat roller 31 is provided downstream of the heat roller 31. The separation claw 35 is swingably attached to the paper guide frame 36 and is urged in a direction in which it comes into contact with the heat roller 31.

On the upstream side of the heat roller 31 and the pressure rubber roller 32, a paper guide 3 for guiding the recording paper sent from the transfer section 20a to the space between the rollers 31 and 32 is provided.
7 is attached to the chassis 7 of the device main body.

An oil felt 38 for supplying silicon oil to the surface of the heat roller 31 is provided above the heat roller 31 to prevent the recording paper from being wound. Further, a thermistor 39 for measuring the temperature of the surface of the heat roller 31 for controlling the temperature of the heat roller 31 is provided. The thermistor 39, the oil felt 38 and the like are covered by a cover 40.

A discharge tray 6 is provided adjacent to and below the downstream side of the heat roller 31 and the pressure rubber roller 32. The recording paper passing through the heat roller 31 and the pressure rubber roller 32 is kicked out by the pressure rubber roller 32. And the output tray 6
Push the recording paper up. As described above, the discharge tray 6
The recording paper stops at the moment it is separated from the nip 33 depending on the angle of the paper, the stock capacity of the paper discharge tray 6, the frame shape of the fixing unit 30, the static electricity of the discharged recording paper, and the curl of the discharged recording paper. Sometimes. Accordingly, in the present invention, in order to reliably kick out the pressure rubber roller 32, the recording paper discharged from between the heat roller 31 and the pressure rubber roller 32 is pressed against the pressure rubber roller 32.
A flexible member that is close to the heat roller 32 and is bent downstream by paper passing and does not hinder the paper passing, for example, a film 34 is attached to the paper guide frame 36.

In this embodiment, since the tip of the film 34 is normally in contact with the pressure rubber roller 32,
Is heated, so a heat-resistant film is used.

Further, since the toner comes into contact with the film 34 immediately after being fixed by the heat roller 31 and the pressure rubber roller 32, the toner fixed on the recording paper becomes a paste, and the discharged recording paper may adhere to the film 34. There is.
For this reason, the leading end of the film 34 is coated with a fluororesin having good releasability to improve the releasability of the toner. Further, a film in which only the leading end is coated with fluorine, a film in which the entire film is coated with fluorine may be used, and the film itself may be made of a fluorine resin.

By the way, normally, the discharged recording paper is separated by a separation claw 35 arranged in contact with the heat roller 31.
It is separated from the heat roller 31. However, the portion of the film 34 of the present invention acts to prevent the separation. For this reason, the film 34 should not be disturbed.
Is desirably disposed as close to the separation claw 35 as possible.

Next, the state of recording paper passing through the fixing unit 30 according to the present invention will be described with reference to FIGS.

First, as shown in FIG. 3, the recording paper 5 on which the toner image has been transferred is fed into the nip 33 between the heat roller 31 and the pressure rubber roller 32 by the pepper guide 37.

As shown in FIG. 4, the recording paper 5 on which fixing has been performed is separated from the heat roller 31 by separation claws 35, and passes while pressing the film 34.

Then, as shown in FIG. 5, when the rear end of the recording paper 5 is separated from the nip portion 33, the film 34 presses the rear end of the recording paper 5 against the pressure rubber roller 32, and the recording paper 5 and the pressure rubber roller 32 and the frictional resistance increases. As a result, the rear end of the recording paper 5 is caught by the pressure rubber roller 32 and kicked out, and the recording paper 5 is reliably stocked on the paper discharge tray 6 as shown in FIG.

[0031]

As described above, according to the present invention, since the paper discharge roller can be omitted, the size of the apparatus can be reduced, and the space, cost and weight can be reduced. Since the recording paper can be reliably ejected from the pressure rubber roller and discharged, there is no risk of paper jams, falling of the discharged recording paper, stacking of the discharged recording paper, discoloration of the discharged recording paper or fire, and reliability and safety. Can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an internal configuration of an image forming apparatus having an analog copy function, a plain paper facsimile function, and a printer function to which the present invention is applied.

FIG. 2 is a cross-sectional view illustrating a configuration of a fixing unit which is a main part of the present invention.

FIG. 3 is a cross-sectional view illustrating a paper passing state of a fixing unit according to the present invention.

FIG. 4 is a cross-sectional view illustrating a paper passing state of a fixing unit according to the present invention.

FIG. 5 is a cross-sectional view illustrating a paper passing state of a fixing unit according to the present invention.

FIG. 6 is a cross-sectional view illustrating a paper passing state of a fixing unit according to the present invention.

[Explanation of symbols]

 Reference Signs List 30 fixing section 31 heat roller 32 pressure rubber roller 33 nip section 34 film (flexible member) 35 separation claw 5 recording paper 6 discharge tray

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (3)

(57) [Claims] A fixing device comprising a heat roller having a heater therein and a pressure roller urged to press the heat roller is provided, and a recording sheet discharged from between the two rollers is directly transferred. An image forming apparatus for discharging paper to a paper discharge unit, wherein a flexible member for pressing a recording sheet discharged from between the two rollers against the pressure roller is provided. 2. The image forming apparatus according to claim 1, wherein the flexible member is disposed near a recording paper separating claw that is disposed in contact with the heat roller. 3. The image forming apparatus according to claim 1, wherein a part or the whole of the flexible member is formed of a material having good releasability from a developing material.