JPH09142698A - Jam detection means protecting mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce troubles of a jam detection means in handling the jam by drawing the jam detection means for a position causing paper sheet clogging lower than a carrying path face, when the paper clogging is detected. SOLUTION: When a jam is detected by a paper sheet detection sensor 3, a cam 6 draws the paper sheet detection sensor 3 so that the tip of a contact element 32 becomes lower than the surface of a paper sheet carrying guide board 4. The cam 6 makes sliding contact with the bottom of the main body part 31 of the paper sheet detection sensor 3 so as to raise and hold the main body part 31 at the upper limit position, and when the cam 6 rotates counterclockwise, the paper sheet detection sensor 3 is lowered to the lower limit position where the tip of the contact element 32 becomes lower than the paper sheet carrying guide board 4. When the jam occurs, the upper side main body 10 is opened so as to easily and quickly handle the jam. In this case, the paper sheet detection sensor 3 is drawn lower than the surface of the paper sheet carrying guide board 4 in a fixation part (A) so that the breakage can be prevented.

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]

A jam detecting unit is provided in the sheet conveying path of the image forming apparatus to detect the occurrence of a jam (paper jam), and to stop the drive of the machine and jam the paper jam. The location is displayed on the display of the operation unit so that the jam can be easily removed.

However, since the structural strength of the jam detecting means is low, an unreasonable force acts on the jam detecting means at the time of jam processing, causing a trouble of damaging the jam detecting means. There was an occasion.

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]

According to the present invention, means for solving the above-mentioned problems are constituted as follows. That is, according to the first aspect of the invention, the jam detecting unit is provided in the sheet conveying path of the image forming apparatus so as to be retractable so as to detect the occurrence of the paper jam, and when the paper jam is detected, the paper jam is detected. It is characterized in that a pulling-down means for pulling down the jam detecting means at the position where the jam occurs is provided below the conveying path surface.

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 detecting means detects the occurrence of a jam, the pulling down means pulls down the jam detecting means below the surface of the conveying path. Breakage of the means can be avoided.

[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.

Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the fixing device,
Reference numeral 1 is a hollow heating roller made of an aluminum alloy material containing a heater (not shown), 2 is a pressure roller that is biased in sliding contact with the heating roller 1, and the surface temperature of the heating roller 1 is the toner melting temperature. The temperature is adjusted to a temperature suitable for fixing (185 ° ± 3 ° C.), and the pressure of the pressure roller 2 increases the efficiency of fixing by heating.

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 micro computer,
According to a preset program, for example, if the downstream paper detection sensor 14 does not detect within a predetermined time after the paper detection sensor 13 detects the paper, 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 more, it is determined that a jam has occurred in the fixing unit [see FIG. 2 (A)].

When a jam is detected by the paper detection sensor 3, the cam 6 pulls down the paper detection sensor 3 until the tip of the contact 32 comes to a position lower than the surface of the paper conveyance guide plate 4. The pulling means), the cam surface of which is slidably brought into contact with the bottom surface of the main body 31 of the paper detection sensor 3, and in the state shown in the drawing, the main body 31 is lifted and held at the upper limit position. When it is rotated counterclockwise, the paper detection sensor 3 is pulled down to the lower limit position where the tip of the contact 32 is below the paper transport guide plate 4 [Fig. 2].
(B)].

The drive system of the cam 6 described above will be explained. A lever 62 fixed to the cam shaft 61 of the cam body 6 is provided.
A slider attached to the tip of the plunger 63 of the solenoid 64 is loosely fitted in the elongated hole 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. 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 if the jammed sheet 5 is removed, so that the sheet detection sensor 3 is protected from damage.
In particular, at the fixing section, the temperature is high due to the heat generated by the heating roller 1, and because it is easy to check the paper jam condition from the paper discharge side, it is easy to quickly perform the jam processing. Even in such a case, the paper detection sensor 3 is fully protected. The solenoid 64 may be demagnetized to shorten the plunger 63.

The fixing unit having such a configuration can be provided in various image forming apparatuses, but can also be provided in a shell type image forming apparatus as shown in FIG. 3, for example. 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 constantly urged by the air cylinder 12 so as to open upward with respect to the lower body 9, and the urging force of the air cylinder 12 is controlled by the operator. When the upper body 10 is pushed down with
It is set so that it descends to the smooths. 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 installed upstream of the above-mentioned hinge 11, and inside the lower main body 9, sheets are continuously fed. A cassette 31 is provided. 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 a heating roller is provided at the most downstream position of the transport path 32. A fixing device including a roller 1 and a pressure roller 2 is provided, and a discharge tray 34 is attached to the downstream side of the fixing device. on the other hand,
The upper body 10 has a built-in photosensitive drum 40,
Charger 41, developing device 42, and cleaning device 4 are provided around it.
3 and the like are arranged, and a transfer device 35 is provided in the lower main body 9 corresponding to the photosensitive drum 40.

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. 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. Furthermore, although the present invention is applied to the microswitch type paper detection sensor 3 in the present embodiment, the paper detection sensor 3 may be of another type, for example, an optical sensor. It can be applied regardless. Although illustration is omitted,
The pull-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 detecting 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.

[0022]

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 described in claim 2, according to 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 the 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 Codes] A ... Transfer image fixing section, 3 ... Jam detecting means, 4 ... Paper transport path, 6 ... Pulling down means

Claims (2)

[Claims] 1. A jam detecting unit is provided in a sheet conveying path of an image forming apparatus so as to be retractable so as to detect the occurrence of a paper jam, and when the paper jam is detected, the jam detection is performed at the position where the paper jam occurs. A jam detecting means protection mechanism comprising pulling means for pulling the means downward from the surface of the conveying path. 2. The jam detecting means protecting mechanism according to claim 1, wherein the jam detecting means is provided in a transfer image fixing portion.