JP3450951B2 - Jam detection means protection mechanism - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique of a jam detecting means protection mechanism provided in an image forming apparatus such as an electrostatographic copying machine or a facsimile.

[0002]

2. Description of the Related Art A jam detecting means is provided in a paper conveying path of an image forming apparatus to detect the occurrence of a jam (paper jam), the machine is stopped, and the paper jam location is detected by an operating section. It is displayed on the display so that jams can be easily removed.

[0003]

However, since the structural strength of the jam detecting means is low, an unreasonable force acts on the jam detecting means when the jam is removed, and the jam detecting means is damaged. Such troubles may occur.

In particular, in the jam detecting means provided in the fixing portion for fixing the transferred image, the temperature of the surroundings is high due to the heat generated by the heating roller, and it is easy to check the paper jam state from the paper discharge side. Therefore, it is often the case that the jammed paper is rushed out during the jam detection process, and in such a case, the jam detection means may be damaged.

The present invention has been made in view of such circumstances.
It is an object of the present invention to provide a jam detecting means protection mechanism in which troubles in the jam detecting means at the time of performing jam processing are reduced.

[0006]

The present invention comprises means for solving the above-mentioned problems as follows. That is, according to the first aspect of the invention, the jam detection means for detecting the occurrence of a paper jam in the sheet conveyance path in the image forming apparatus has its contactor projected upward from the sheet conveyance path surface.
Upper limit position and its contacts are below the paper transport path surface.
It is installed in the retracted lower limit position so that it can appear and disappear ,
When the jam detection unit detects the occurrence of a paper jam, the controller connected to the jam detection unit
And a drive-type pulling-down means for pulling down the jam detecting means at the position where the paper jam occurs by the control output to the lower limit position where the tip of the contactor is pulled down below the transport path surface. I am trying.

The invention according to claim 2 is characterized in that the jam detecting means in the invention according to claim 1 is provided in the transfer image fixing portion.

With this structure, when the jam detection unit detects the occurrence of a jam, the controller detects the jam.
Pull below the transport path surface control output pull down means is driven by the jam detection means the tip of the contact piece of
Since pulled by the lower limit position until put, it is possible to avoid breakage of the jam detection means during the jam.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a main structure of a fixing unit (transfer image fixing unit), and reference numeral 1 is a hollow heating roller made of an aluminum alloy material having a heater (not shown) incorporated therein, and 2 is a sliding contact force for the heating roller 1. The surface temperature of the heating roller 1 is adjusted to a temperature (185 ° ± 3 ° C.) suitable for toner fusion and the fixing efficiency is improved by the pressure applied by the pressure roller 2. It has become so. In addition, 1a is a peeling claw and 1b is a temperature sensor.

Reference numeral 3 denotes a paper detection sensor (jam detection means) for detecting the paper to be conveyed. A main body portion 31 of the paper conveyance guide plate (paper conveyance path) 4 is provided in a downward direction at a pair. Is guided by the guide plates 41 and 42 in the up-and-down direction, and at its upper limit position, its contactor 32 is projected upward from a notch hole (not shown) formed in the sheet conveying guide plate 4, and at the lower limit position, contact is made. The child 32 can be retracted below the sheet conveying guide plate 4. It should be noted that sliders 33, 33 projecting from both sides of the main body 31 are loosely fitted in elongated holes (not shown) formed in the guide plates 41, 42 in the vertical direction .

In addition to the paper detection sensor 3, other paper detection sensors 13 and 14 (see FIG. 3) are provided on the upstream side of the paper conveyance path 32.
, Each sensor 3, 13, 14 is connected to a controller 7 composed of a microcomputer,
According to a pre-set program, for example, the paper detection sensor
If the downstream paper detection sensor 14 does not detect within a predetermined time after the paper 13 is detected, it is determined that a jam has occurred between the sensors 13 and 14. Further, when the paper detection sensor 3 of the fixing unit continuously transmits the paper detection signal for a predetermined time or longer, it is determined that a jam has occurred in the fixing unit [FIG. 2].
(See (A)].

When a jam is detected by the paper detection sensor 3, 6 is for lowering the paper detection sensor 3 to a lower limit position where the tip of the contact 32 is retracted below the surface of the paper conveyance guide plate 4. It is a cam ( driving type lowering means), and its cam surface is brought into sliding contact with the bottom surface of the main body 31 of the paper detection sensor 3, and the main body 31 is lifted and held at the upper limit position in the state shown. When the cam 6 rotates counterclockwise, the paper detection sensor 3 is pulled down to the lower limit position where the tip of the contact 32 is retracted below the paper transport guide plate 4 (see FIG. 2B).

Explaining the drive system of the cam 6 described above, a lever 62 fixed to the cam shaft 61 of the cam body 6 is described.
A slider attached to the tip of the plunger 63 of the solenoid 64 is loosely fitted in the slot of the solenoid 64, and a tension spring 65 is stretched between the main body 31 and the bottom of the lower main body 9. ing. When the solenoid 64 is demagnetized, the main body 31 is at the upper limit position, and when the solenoid 64 is excited, the plunger 63 contracts and the main body 31 is lowered to the lower limit position.

When a jam is detected by the above-mentioned paper detection sensor 3 (see FIG. 2A), a jam output is displayed on the display provided in the operation section (not shown) by the control output from the controller 7. At the same time, the solenoid 64 is excited, the plunger 63 contracts and the main body 31 descends, and as shown in FIG.
Is pulled down below the surface of the sheet conveying guide plate 4.

In this state , the contact 32 does not touch the sheet 5 even when the jammed sheet 5 is removed, so that the sheet detection sensor 3 is protected from damage. In particular, in the fixing section, the temperature is high due to the heat generated from the heating roller 1, and it is easy to check the state of the paper jam from the paper discharge side. In this case also, the protection of the paper detection sensor 3 is perfect. The solenoid 64 may be demagnetized to shorten the plunger 63.

The fixing unit having such a structure can be provided in various image forming apparatuses, but can also be provided in, for example, a shell type image forming apparatus as shown in FIG. The structure will be described. The main body 8 is composed of a lower main body 9 and an upper main body 10, and the upper main body 10 is opened to one side by a hinge 11 as shown in the figure.

The upper body 10 is urged against the lower body 9 by an air cylinder 12 so as to always open upward. The urging force of the air cylinder 12 is manually applied by an operator to the upper body 10. When is pressed down,
It is set to smoothly descend. A hook (not shown) is attached to the upper body 10,
The hook engages with a locking member attached to the lower body 9 so that the upper body 10 is moved to the lower body 9.
It can be closed by overlapping.

A manual feed tray 30 for manually feeding sheets is attached upstream of the hinge 11, and a paper feed cassette 31 for continuously feeding sheets is provided inside the lower main body 9. Has been. A transport path 32 for transporting sheets from the manual feed tray 30 and the paper feed cassette 31 is provided on the upper surface of the lower main body 9, and the heating roller 1 and the heating roller 1 are provided at the most downstream position of the transport path 32. A fixing device A including the pressure roller 2 is provided, and a discharge tray 34 is attached further downstream thereof. On the other hand, a photosensitive drum 40 is built in the upper main body 10, and a charging device 41, a developing device 42, a cleaning device 43, etc. are arranged around the photosensitive drum 40. It is provided on the side body 9.

In such a shell type image forming apparatus, when a jam occurs, the upper main body 10 is opened as shown in the drawing,
Jam processing can be performed easily and quickly, and at that time, in the fixing unit, the paper detection sensor 3 is retracted below the surface of the paper transport guide plate 4, so that the damage is prevented. It is needless to say that the other paper detection sensors 13 and 14 can have the same configuration to avoid damage and can be similarly applied to other models. Further, although not shown , the pulling-down means 6 may be constituted by a link instead of the cam, and its drive source may be a motor.

FIG. 4 shows a different embodiment of the invention,
The paper detection sensor 3 is directly pulled down by a solenoid 66. In this case, the solenoid 66 is fixed to the bottom of the lower main body 9 in an upright position, and its plunger 67 is fixed.
Is fixed to the bottom surface of the main body 31.

[0021]

As described above, according to the first aspect of the present invention, when the paper jam occurs, the jam detecting means is pulled down below the sheet conveying path surface. It is possible to prevent the jam detecting means from being damaged.

According to the invention of claim 2, claim 1
In the invention described in (1), the jam detection means protection mechanism is provided in the transfer image fixing section that is apt to perform jam processing because the jammed state is easily checked from the paper discharge side due to high temperature, The jam detecting means can be protected even if the jam processing is performed in a hurry.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of a jam detecting means protection mechanism of the present invention.

FIG. 2A is an explanatory diagram of a state in which the jam is detected,
(B) is an explanatory view of a state in which the jam detecting means is pulled down.

FIG. 3 is a schematic configuration diagram of the image forming apparatus.

FIG. 4 is a longitudinal cross-sectional view of a main part showing a different embodiment of the jam detecting unit protection mechanism of the present invention.

[Explanation of symbols]

A ... Transfer image fixing section, 3 ... Jam detecting means, 4 ... Paper transport path, 6 ... Pulling down means, 7 ... Controller, 32 ... Contact
Child.

Claims (2)

(57) [Claims] 1. A paper conveyance path in an image forming apparatus
Its contact the jam detection means for detecting the occurrence of a paper jam
And the upper limit position where the
Lower limit of contact retracted below the paper transport path surface
It is installed in and out of position, and this jam detection hand
The occurrence of paper jam is detected by the stage, jam detection
The control output from the controller connected to the means
Its contact the jam detection means of the position where the paper jam occurs I
The tip of the tentacle was retracted below the transport path surface .
A jam detecting means protection mechanism comprising drive-type pulling means for pulling down to a lower limit position . 2. The jam detecting means protecting mechanism according to claim 1, wherein the jam detecting means is provided in a transfer image fixing portion.