JPS63300048A - Passing sheet inspector at fixing instrument of image formation device - Google Patents

Abstract

PURPOSE:To conduct the detection of the passing of a sheet through a simple constitution and detect a jam by outputting a signal according to the change of rotation due to the change of load at the time of carrying-in the sheet to a rotational body, and discriminating and inspecting the rotational change of the rotational body based on the signal. CONSTITUTION:A fixing instrument 23 is made up of an upper fixing unit 26 equipped with an upper pressurization roller 25 and a lower fixing unit 29 quipped with a lower pressurization roller 27, and a sheet of paper carried is pressurized and fixed as pressurization rollers 25, 27 are mutually press-contacted. A photo detector 35 and a flange 33 which is formed with a number of slits and arranged so as to interrupt the light passage of the photo detector 35, are provided at the lower fixing unit 29, which constitutes an inspecting device 40. The flange 33 is fixed at the gear 31 of the shaft portion of the lower pressurization roller 27. Accordingly, the pulse of a frequency which is in accordance with the rotation number of the pressurization roller 27 is outputted by means of the photo detector 25, and the change of rotation is inspected by an inspected means 37, and the passing of a sheet is inspected. Accordingly, when an inspection is not conducted within a predetermined time, it is decided as a jam.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application The present invention relates to a passing sheet detection device for detecting the passage of a sheet in a fixing device of an image forming apparatus such as a copying machine, a facsimile machine, or a laser beam printer.

(B) Prior Art Conventionally, for example, in a copying machine, the copying process is carried out by dropping sheets into the machine, so there is always a risk of sheets jamming inside the machine.

Therefore, in order to know whether the sheet is stuck inside the machine, a sensor is usually installed to detect the sheet passing through the fixing device, and if the sheet is not detected within the scheduled time, the sheet is stuck inside the machine. It is determined that

A sensor that is often used as such is the sensor that comes out of the fuser!・Pushes the actuator installed immediately after the fixing mold, and its movement is detected by a foot sensor, a Hall element, etc.In addition, the notebook that comes out of the fixing device reflects light. Alternatively, if light is blocked, the actuator is not needed, but in the former case, the smoothness of the sheet surface varies depending on the type, so the reflected light is not constant, and in the latter case, overhead projector (OHP)
This method has not been put into practical use because it is difficult to detect sheets with high light transmittance, such as sheets for I, and cannot achieve satisfactory performance.

In a sensor using the above-mentioned actuator, it is necessary for the seat to push the actuator reliably. For example, in order to be able to push the actuator reliably even with a weak seat, normally, as shown in Fig. 3, A plurality of actuators 41 are provided on a paper ejection roller shaft 42 disposed immediately after the fixing device 23.
It is arranged so that it can swing freely between the two. The actuator 41 is constructed between the paper ejection rollers 43 and the presser rollers 45 that are in contact with the paper ejection rollers 43, and is positioned so as to block the paper passage. When the sheet I passes, it is pushed by the sheet and rotates in the direction of the arrow, and this rotation is detected by the photosensor 47 located above via the link 46. Further, the pressing rollers 45- are pressed against the paper ejection rollers 43 by springs, and the position of the sheet is constant between the presser rollers 45 and the paper ejection rollers 43. Always stable actuator 4
You can press 1.

Note that reference numeral 49 indicates an actuator holder that supports the actuator 41.

→ Problems to be Solved by the Invention Incidentally, in the sensor using the above-mentioned actuator, in addition to the sensor 47, there are an actuator 41, an actuator holder 49, in some cases a link 46, and a paper ejection roller 43... Presser foot roller 4
5... is required, which increases the size of the device and increases the cost.

(5) Means for Solving the Problems The present invention aims to solve the above-mentioned problems. For example, as shown in FIG. Rotation signal output means 33.35 outputs a signal, and rotation of the rotary bodies 25, 27 when the sheet is carried into the rotary bodies 25, 27 based on the output signals of the rotation signal output means 33, 35. The present invention is characterized in that it is provided with rotating body variation discrimination/detection means 37 for discriminating and detecting variation.

(e) Operation Based on the above-mentioned means, when the sheet I passes through the fixing device 23, the rotation (by the g output means 33.35, the sheet) -
into the rotating bodies 25, 27, or the rotating bodies 25, 27
A signal corresponding to rotational fluctuations of the rotary bodies 25 and 27 due to load fluctuations occurring in the fixing device 23 during unloading is outputted. Then, based on the output signal, the rotational variation of the rotating body 25, 27 at the time of conveying the sheet is discriminated and detected by the rotating body variation determining/detecting means 37, and passage of the sheet through the fixing device 23 is detected.

(F) Examples Examples of the present invention will be described below with reference to the drawings.

As shown in FIG. 2, the copying machine 1 has a bottom plate 3 integrally molded with a plastic mold at the bottom of the machine body 2, and a base plate 5, a lighting unit 6, and a lens 7 on the top of the machine body 2. There is. Further, approximately in the center of the body 2 is a photosensitive drum 9 and a primary charger 1 disposed around the photosensitive drum 9.
0, a copying section 13 is disposed in which a developing device 11 and a cleaner 12 are integrated into a cartridge. Further, on the right side of the copying section 13 in the figure, there is a paper feed tray for storing a large number of sheets 1-S. -15 is arranged, and the paper feed cassette)
A pickup roller 16 is disposed facing the photocopy section 15, and a resist roller 17 and a transfer guide 19 are disposed between the pickup roller 16 and the copying section 13.

Further, below the copying section 13, a transfer belt m device 20 and a transfer conveyance roller 21 are arranged, and the transfer conveyance roller 2]
A fixing section guide 22 is formed on the upper surface of the bottom plate 3 downstream of the fixing section guide 22 . The fuser 23 is located on the left side of the fuselage 2 in the figure.
are arranged, the fixing device 23 and the upper pressure roller 25
The upper and lower fixing units 26 and 29 are connected to each other about a rotating shaft 30 so as to be openable and closable.

Further, these upper and lower fixing units 26 and 29 are pressurized by springs so that upper and lower pressure rollers 25 and 27 come into pressure contact with each other. Apply pressure to the sheet to fix the image.

In this embodiment, the pressing force of the fixing device 23 is 1.5 mm in the axial direction of the portions of the upper and lower pressure rollers 25 and 27 that sandwich the sheet. 20 kg per cm, maximum copy size A
A total of 420 kg of pressure is applied to the four sizes of seats. Also, since high pressure is applied in this way, it takes 3 kg to rotate the pressure roller when the paper is not passing.
-cm, a torque of 25 to 35 kg-am is required when passing sheets, and large load fluctuations occur during sheet passing, and these load fluctuations occur instantaneously as the sheets are carried out. Further, the pressure roller 27 is rotationally driven by a motor via a gear train, but as mentioned above, load fluctuations occur, so when sheets are loaded and unloaded, elastic deformation of the gear train and rotational fluctuations of the motor occur. A phenomenon occurs in which the rotation of the upper and lower pressure rollers 25 and 27 momentarily fluctuates. This variation is at a sufficiently detectable level of 4 to 8%.

On the other hand, as shown in FIG. 1 (al), the fixing device 23 includes a photodetector 35 attached to the upper fixing unit 29 and a flange having a large number of slits 32 and arranged to block the optical path of the photodetector 35. ;33 (Fig. 1 fbl
A paper passing detection device 40 is provided.

The flange 33 is fixed to a gear 31 disposed on the shaft portion 27a of the lower pressure roller 27,
The lower pressure roller 27 transfers the driving force from the gear train to gear 3.
1 and rotates, the detector 35 outputs a pulse with a frequency corresponding to the number of rotations of the lower pressure roller 27. Then, the sheet passing detection device 40 detects the photodetector 35 by the rotating body variation determination/detection means 37 of the control section 36.
I am monitoring the frequency of the pulses output from Sea 1-
When S is carried into or out of the upper and lower pressure rollers 25° 27, rotational fluctuations due to load fluctuations of the pressure roller 25° 27 are determined and detected from, for example, fluctuations in a predetermined frequency, and seas 1 to S are passed. Detect. If the passage of C+-S is not detected within a predetermined time after the start of the copying operation, it is determined that there is a paper jam.

Since this embodiment has the above-described configuration, the sheets 1-S stored in the paper feed cassette 15 are separated one by one by the pickup roller 16 and conveyed to the registration rollers 17. Then, the sea+-S is the registration roller 17.
After passing through a transfer guide 19 and coming into contact with the photosensitive drum 9, the toner image is transferred by a transfer charger 20, and then conveyed over a fixing section guide 22 and transferred to a fixing device 23. Then, the sheet S sent to the fixing device 23 is pressed against pressure rollers 25 and 27 above and below the fixing device W23.
The paper is carried in between the paper sheets, is pressed against the upper and lower pressure rollers 25 and 27, the image is fixed, and is ejected onto the paper ejection tray 39.

On the other hand, the paper passing detection device 40 detects the pressurizing roller 2 of the fixing device 23.
When the sheets 5 and 27 are carried in, the passage of the sheet S is detected based on the rotational fluctuation, and if the passage of the sheets 1-S is not detected within a predetermined time after starting the copying operation, it is determined that there is a paper jam, and the paper is jammed. Output a signal.

Note that in the above-described embodiment, the rotational fluctuation of the pressure roller is detected using a flange having a large number of slits and a photodetector, but the present invention is not limited to this.

Further, when the motor is a servo motor, a sensor for detecting the rotation speed of the motor may be used to detect rotation fluctuations of the motor.

(G) As described in detail, according to the present invention, there is provided a rotation signal output means for outputting a signal corresponding to the rotation of the rotating body, and a rotation signal output means for outputting a signal corresponding to the rotation of the rotor, Since a rotary body variation determination/detection means for determining and detecting the rotational variation of the rotary body when the sheet is carried into the rotary body is provided, the rotational variation of the rotary body when the sheet is carried into the rotary body of the fixing device is determined. - It is possible to sufficiently detect the passage of the sheet 1- through the constant plate 11 without using many members such as actuators and paper ejection rollers.

Therefore, for example, the device can be made smaller and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 [a] is a side view showing a sheet passing detection device disposed in a fixing device of a copying machine according to an embodiment of the present invention, (bl is a detailed view of its flange, and FIG. 2 is a side view of the copying machine. 3 are side views of a conventional passing sheet detection device using an actuator. 1. Image forming device (copying machine), 23. Fixing device
, 25.27 Rotating body (upper pressure roller, lower pressure roller), 33, 35...Rotation signal output means (flange, photodetector), 37...Rotating body fluctuation discrimination/detection means, S...C+ −.

Claims (2)

[Claims] (1) In an image forming apparatus that includes a fixing device consisting of a rotating body and detects the passage of an unfixed sheet when the fixing device fixes an unfixed sheet, a signal is output in accordance with the rotation of the rotating body. a rotation signal outputting means; and a rotating body variation determining/detecting means for determining and detecting a rotational variation of the rotating body when the sheet is carried into the rotating body based on the output signal of the rotational signal outputting unit. A passing sheet detecting device in a fixing device of an image forming apparatus, characterized in that the passing sheet detecting device is provided. (2) A passing sheet detection device in a fixing device of an image forming apparatus according to claim 1, wherein the fixing device is a pressure fixing device.