JP2003057892A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent jamming process from becoming difficult due to paper being wrapped up by press roll because of belated detection by speedily detecting the jamming when an accordion jam occurs in a paper delivery part. SOLUTION: The rotating angle of a paper delivery sensor lever provided in a paper delivery guide is installed so that it is made larger when the accordion jam occurs than in normal copying. In this case, a photo interrupter light shielding plate of the paper delivery sensor lever is formed in a slit shape and the jam is detected by the slit shape of the light shielding plate when the accordion jam is generated.

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 or an electrophotographic printer.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or an electrophotographic printer, as a recording material conveying means, a pair of rollers which presses and conveys a pair of rollers at a constant pressure is often used. Even in the apparatus, it is general that at least one pair of conveying rollers is provided.

As a means for fixing the toner image on the recording material conveyed by the conveying means, a heat roller system,
Pressure fixing system, more recently JP-A-63-31318
As seen in Japanese Patent Laid-Open No. 2 (1994), a fixing method using a fixed heating head and a thin film (hereinafter referred to as film fixing) is also considered.

In any of these fixing methods, a pressure member is provided in each of the fixing methods, and the toner image on the recording material is conveyed while pressing the toner image on the recording material by the pressure contact portion formed by the pressure member. It is known that fixing processing is performed.

As described above, in the conveying means and the fixing means for nipping and conveying the recording material, the recording material is in a pressurized state, so that if the recording material is jammed in this portion, it is easily processed. However, if the recording material is forcibly pulled out, the recording material is broken and remains in the apparatus.

Therefore, generally, the pressure is reduced to reduce the load, the pressure contact portions are separated from each other, the roller pair is rotated by providing a manual handle, and the entire main body is referred to as an upper main body. A so-called clam which is divided into a lower main body, in which the upper main body can be freely opened and closed around a rotation center provided on the upstream side (paper feed side) in the recording material conveyance direction, and the paper discharge side downstream in the recording material conveyance direction is opened. There is a shell type structure or a structure in which a part of the main body is opened to facilitate the jam processing.

[0007]

However, there are drawbacks in the various configurations described above. Especially when the paper ejection section is blocked due to overloading of the paper ejection tray,
When a jam that folds while waving between the upper and lower guides for paper ejection (hereinafter referred to as an accordion jam) occurs, there is no means for immediately detecting it, and the paper continues to rotate until the paper ejection sensor detects a delay jam.

Therefore, even in the case of a jam caused by the leading edge of the sheet, the entire transfer material is conveyed to the location where the jam occurs, and the jam processing becomes more difficult (the state shown in FIG. 6).

Further, the transfer material jammed in the paper discharge section may be wound around the pressure roller and may develop into a jam around the pressure roller. When the jam around the pressure roller occurs, it may not be possible to remove the jam without disassembling the fixing device, and if the transfer material is forcibly pulled out, the pressure roller and the film may be damaged.

[0010]

SUMMARY OF THE INVENTION The present invention is an image forming apparatus having the following configuration.

A slit is formed in the light-shielding plate by a paper detecting means composed of a lever member provided on a paper-discharging guide for guiding the transfer material from the fixing unit to the paper-discharging unit, and a photo interrupter which is turned on / off by the light-shielding plate of the lever. 3 depending on the shape
It is characterized in that the position of each lever member is detected.

Further, two photo interrupters may be used instead of using the slit shape for the light shielding plate.

With this configuration, when an accordion jam occurs from the fixing unit to the paper discharge unit, the rotation angle of the lever member becomes larger than that at the normal time, and the photo interrupter detects the slit shape of the light shielding plate, so that the jam can be immediately generated. Can be detected. This detection method can detect a jam earlier than the jam detection based on the retention detection that has been conventionally used, and stop the sheet conveyance. Also, two types of information, that is, the presence / absence of paper and the accordion jam detection, are stored in one lever member. The problem caused by the accordion jam can be solved by an inexpensive and simple method that can be obtained by the photo interrupter.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 is a vertical sectional view of the copying machine according to the first embodiment of the present invention. The upper frame 31 and the lower frame 32 are connected by a paper feed side hinge 33, and the upper frame 31 is of a clamshell (vanillo) type configuration in which the upper frame 31 is swingably opened and closed about a support shaft. The document stored on the document table 34 is illuminated by an exposure lamp 35 that moves along the document table 34,
The optical image reflected by the original is adjusted in optical path length by the moving mirror 36, passes through the lens 46, is reflected by the fixed mirror 37, and is formed on the photosensitive drum 39 provided in the process cartridge 38.

The process cartridge 38 is a cartridge in which the charging means, the developing means, the cleaning means and the photosensitive drum 39 are integrally formed, and the cartridge can be attached to and detached from the copying machine main body. Alternatively, at least one of the charging means, the developing means, and the cleaning means and the photosensitive drum are integrally made into a cartridge which can be attached to and detached from the main body of the copying machine, and the photosensitive drum 39 rotates in the direction of the arrow in the figure. As the photosensitive member on the surface moves due to rotation, uniform charging, latent image formation by image formation of the optical image, and development are performed, and a toner image is formed on the photosensitive drum 39.

On the other hand, the paper feed cassette 40 to the paper feed roller 41
Then, the transfer material sent out by one sheet is sent to the registration roller 43 by the sheet feeding / conveying means 42 composed of a conveying path and a conveying roller, and is synchronized with the toner image on the photosensitive drum 39 so that the photosensitive drum 39 and the transfer roller 44 are synchronized. Then, the toner image is transferred to a transfer material, and after the transfer, the belt conveying means 4
The transfer material supporting the toner image at 5 is sent to the fixing device 25.

The arrival of the leading end of the transfer material having the toner image fixed by the fixing device 25 is detected by the paper discharge sensor 23,
At the same time, the escape of the trailing edge is also detected to detect the retention of the paper due to the jam at the exit of the fixing device 25. The transfer material that has passed through the paper discharge sensor 23 is guided to the paper discharge upper guide 21 and the paper discharge lower guide 22, is sent to the paper discharge roller pair 17, and is discharged to the outside of the machine.

In the above, when a jam (paper jam) occurs in the paper feed roller 41, the transfer means 42 and 45 for transferring the transfer material, the registration roller 43, the transfer roller 44, and the fixing device 25, and the replacement of the process cartridge 38, At the time of other maintenance inspections, the upper frame 31 is attached to the paper feed side hinge 33.
The upper frame 31 and the lower frame 32
The space is opened like a crocodile, and after a predetermined work, the upper frame 31 is swung toward the lower frame 32 and closed.

Next, the details of the fixing device 25 will be described.

In the image forming apparatus using the electrophotographic system, on-demand fixing is adopted as a fixing device for fixing an electrophotographic image in order to save energy and shorten the wait time. Figure 1 (a)
It is configured as shown in. In the figure, 15 is a first stay member, which also serves as an inner surface guide member of the fixing film 14 and a holding member of the heating body (heater) 24.
Reference numeral 16 denotes a second stay member, which is made of a metal material such as aluminum and serves to uniformly apply the pressure force from the spring member 26 to the first stay member 15 and to extend the length of the fixing device 25. It is intended to improve the heat conduction in the direction and reduce the uneven temperature distribution. Reference numeral 13 denotes a pressure roller, which comprises a cored bar 13a and a part 13b on the surface of which the solid silicon rubber is coated with terax, and is rotatably supported by a frame 27 via a bearing (not shown). , Is rotated by a main motor (not shown) in the direction of arrow A (counterclockwise).

Next, the operation of the paper discharge sensor 23 is shown in FIG.
Will be explained.

The paper discharge sensor 23 includes a transfer material detecting lever portion 23-a for detecting the presence or absence of the transfer material and the photo interrupter 2.
The second optical axis 22-a is formed of a light blocking plate 23-b that opens and blocks light, and a slit portion 23-c is further provided.

The discharge sensor lever portion 23-a is attached to the transfer material 3
While 0 is passing (FIG. 1 (b)), the paper discharge sensor 23 rotates in the direction A in FIG. 2 (b), and the light shielding plate 23-b moves the optical axis 22-a of the photo interrupter 22. The light is shielded and the transfer material 30 is detected.

After the transfer material 30 has escaped, it is rotated in the direction B in the figure by a return spring (not shown) to return to the state of FIG. 2 (a).

In the ON / OFF sequence of the photo interrupter 22 at the time of continuous copying, the above operation is repeated, so that FIG.
It becomes like (a).

However, if the leading edge of the transfer material 30 stays in the vicinity of the discharge roller pair 17 or if the discharge tray (not shown) is fully loaded to prevent the transfer material from being discharged from the machine, FIG. )
It becomes an accordion jam as shown in. At this time, the paper discharge sensor lever portion 23-a is pushed up to the same height as the paper discharge upper guide 21 by the transfer material 30, so that FIG.
As shown in (c), the rotation angle of the paper discharge sensor 23 from the nominal position is larger than that during normal paper passing (state in FIG. 2C).

At this time, the light shielding plate 22-b has the slit portion 22.
The optical axis 22-a of the photo interrupter 22 after passing through -c.
Rotate to a position to block light.

Therefore, the ON / OFF sequence of the photo interrupter 22 when an accordion jam occurs is as shown in FIG. 5 (b). ON of photo interrupter 22
A control circuit (not shown) for processing the ON / OFF signal is ON shorter than t1 ′ (t1> t1 ′) set in consideration of the time t1 to be turned ON between sheets during continuous copying and the variation margin between sheets. It is set to stop the device when receiving a signal. Further, since the paper feed timing is controlled so that the paper interval is always constant, the above t1 and t1 ′ are constant.

As shown in FIG. 5B, the relationship between the ON signal t2 detected by the slit portion 23-c and the t1 and t1 'is t1>t1'>> t2. Therefore, when t2 is detected, the apparatus stops. To do.

Next, a jam processing method after detecting the accordion jam will be described.

After the sheet conveyance is stopped by the detection of the photo interrupter 22, the upper frame 31 is rotated and opened.

When the upper frame 31 is rotated, the fixing drive swing gear (not shown) attached to the upper frame 31 is released, and the jam sheet can be pulled out in either direction of arrows A and B in FIG. Becomes The fixing device of this embodiment does not have a pressure releasing mechanism between the film 14 and the pressure roller,
By releasing the drive to fixing and pulling out the sheet,
The film 14 and the pressure roller 13 are driven to rotate to process the jammed sheet.

(Second Embodiment) FIG. 3A shows a second embodiment of the present invention.

The structure is different from that of the first embodiment.
The paper discharge sensor 23 has no slit portion, and in addition to the photo interrupter 22 for detecting the transfer material, the photo interrupter 28 for detecting the accordion jam.
It is equipped with.

Next, the operation will be described.

When the paper discharge sensor 23 detects the transfer material 30, the light shielding plate of the paper discharge sensor 23 shields the optical axis 22-a of the photo interrupter 22 and the photo interrupter 22 transfers the transfer material 30, as shown in FIG. 3B. To detect. In normal continuous copying, the photo interrupter 22 is repeatedly turned ON / OFF, and the optical axis 28-b of the photo interrupter 28 remains in the ON state without being shielded.

When the accordion jam occurs as shown in FIG. 3C, the rotation angle of the paper discharge sensor 23 is as shown in FIG.
It becomes larger than (b), and both the photo interrupters 22 and 28 are shielded from light and turned off.

The control circuit (not shown) is a photo interrupter 2.
When the OFF signal of 8 is detected, the main body is stopped.

The jam processing method is the same as that in the first embodiment.

[0041]

As described in detail above, the present invention is a configuration of the first embodiment in an image forming apparatus such as an electrophotographic apparatus, and is a sheet discharge sensor and a photo interrupter having a light shielding plate having a slit portion. Alternatively, in the configuration of the second embodiment, the paper discharge sensor and the two photo interrupters cause the paper discharge sensor lever portion to be pushed up by the transfer material when an accordion jam occurs, so that the rotation angle of the paper discharge sensor is larger than usual. By arranging so that
Accordion jam can be detected immediately.
As a result, as shown in FIG. 5B, the time t3 from the occurrence of the accordion jam to the main body stop is t4 (FIG. 5).
(See (b)), and it is possible to solve jam improving property and prevent winding of the transfer material around the pressure roller and the fixing film due to delay in jam detection by an inexpensive and simple method. .

[Brief description of drawings]

FIG. 1 is an explanatory diagram of first and second embodiments.

FIG. 2 is an explanatory diagram of the first embodiment.

FIG. 3 is an explanatory diagram of a second embodiment.

FIG. 4 is an explanatory diagram of the first embodiment.

FIG. 5 is an explanatory diagram of the first embodiment.

FIG. 6 is an explanatory diagram of a conventional example.

[Explanation of symbols]

31 upper frame 32 lower frame 33 Paper feed side hinge 34 Platen 35 exposure lamp

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H027 DC14 DE02 DE03 DE07 DE10                       ED19 ED25                 2H033 AA18 AA37 BA10 CA09 CA22                 2H072 AA02 AA17 AB28 EA02 EA16                       FB00                 3F048 AA02 AB01 BA14 BB09 BD02                       CC03 DA09 EB40

Claims (4)

[Claims] 1. A heating member that nips and conveys a transfer sheet,
A fixing unit including a pressure member that is in pressure contact with the heating member, a discharge unit that discharges the transfer paper conveyed from the fixing unit to the outside of the apparatus, and a discharge unit that guides the transfer paper from the fixing unit to the discharge unit. An image forming apparatus having a paper guide member and a paper detection unit arranged in the paper discharge guide in the transfer direction of the transfer paper, wherein the paper detection unit is a lever member rotatably supported depending on the presence or absence of paper, and ON / OFF by turning the lever member
An image forming apparatus, which is configured by a sensor member configured so as to be capable of detecting three rotational positions of the lever member by the sensor member. 2. The lever member comprises a light-shielding plate for reflecting light, and the sensor member is constituted by a photo interrupter which is turned on / off by reflecting and diffusing light depending on the presence or absence of the light-shielding plate. The image forming apparatus according to claim 1, wherein the light shielding plate has a slit-shaped portion. 3. The photo interrupter is turned on to detect a third rotational position of the lever member other than the presence / absence of a transfer material.
Is detected when the photo interrupter is turned on between sheets during continuous sheet feeding, and is detected by the slit shape of the light shielding plate.
The image forming apparatus according to claim 2, wherein a time t2 when N / OFF is t1> t2. 4. The paper detecting means is composed of one lever member and two previous photo interrupters, the lever member includes a light-shielding plate for reflecting light, and the light-shielding plate is used for the two light-shielding plates. Photo interrupter is ON /
The image forming apparatus according to claim 1, wherein the image forming apparatus is turned off.