JPH02226178A - Paper guide device of heat roller fixing device - Google Patents

Abstract

PURPOSE:To prevent copy quality from deteriorating owing to the disorder of an image by providing a guide member which is displaced between the paper guide position of the entrance and a paper non-guide position above the entrance, and displacing the guide member according to the timing of paper feeding. CONSTITUTION:Paper 1 is guided by a paper guide plate 6 to nearby a fixation roller 9 and a pressure roller 11. When the paper 1 is clamped and conveyed to the entrance part of the fixation roller 9 and the tail end is sensed by a tail end detection sensor 3, the sensor 3 detects the rear end of the paper 1 and sends its signal to a solenoid 4; when the solenoid 4 turns on, the paper guide plate 6 is displaced upward, so that the tail end part of the paper 1 never contacts the guide plate even if floating slightly. The ON state of the solenoid 4 is held for a constant time and the guide plate returns to the lower fixed position before the paper top end of next paper is entered. Consequently, the copy quality is prevented from deteriorating owing to the disorder of an image.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a paper guide device for a copying machine, facsimile machine, or printer using a heat roller fixing device.

(Prior Art) Conventionally, as shown in FIG. 5, when the machine is ready for copying before fixing, the heat fixing roller 20 and the pressure roller 2
A spur 22 disposed at the entrance of the copy paper 24 is protruded downward from the guide plate 23 to prevent the toner image 25 on the copy paper 24 from coming into contact with the guide plate 23 and disturbing the toner image 25. When not copying, the spur 22 is placed on the guide plate A paper guide device of a thermal roller fixing device that is displaced inside the paper guide 23 so that it cannot be touched by a user's hand is known.

(Problems to be Solved by the Invention) In the above-mentioned prior art, there is no technical difficulty in guiding ordinary paper to the fixing roller section. However, paper is not always flat; rather, it is often curled.

In order to guide the curled paper to the fixing roller section, the guide member must be as close as possible to the fixing roller section. If not, the leading edge of the paper will not be bitten by the fixing roller section and the paper will Jam. Once the paper enters the fixing roller section, it has a fairly large conveying force, so the paper is fed as the fixing roller rotates. The toner image transferred by the transfer section remains unfixed on the paper.

The rear end of the paper springs upward depending on the strength (rigidity) of the paper, although it changes depending on the slow speed and pressure of the nip section.

This splashing causes the unfixed toner on the paper to rub against the guide plate near the fixing roller area.
This has the problem of disturbing the image and significantly reducing copy quality.

(Means for Solving the Problems) The present invention aims to solve the above problems, and the present invention displaces the paper guide member disposed at the entrance of the fixing section to a paper guide position and a paper non-guide position above the entrance. The present invention is characterized in that a member is provided and the member is changed in accordance with the timing of paper passing.

(Example) FIG. 1 shows the function of the fixing section. A paper 1 is conveyed to the fixing section by a conveyor belt 2. The leading edge of the paper usually has some curl as shown in Figure 1. In order to guide such curled paper to the fixing section, it is guided by the paper guide plate 6 to the vicinity of the fixing roller 9 and pressure roller 11. Fixing roller 9
A trace amount of silicone oil is applied to the surface by an oil application device 8 in order to ensure releasability from the toner. Furthermore, it is well known that a heater 10 is installed inside the fixing roller. In the state shown in FIG. 1, although the paper is curled, it is guided by the fixing roller section.

In FIG. 4, the paper is gripped by the fixing roller, conveyed, and its rear end is placed inside the conveyor belt 2. In FIG. The state when the rear end detection sensor 3 is passed is shown. When the sensor 3 detects the rear end of the paper 1, the signal is sent to the solenoid 4, which turns on (suction). When the solenoid 4 is turned on, the paper guide plate 6 is displaced upward, reaching a height at which it does not come into contact even if the rear end of the paper lifts up a little.

The ON state of this solenoid 4 is maintained for a certain period of time,
It returns to the downward position before the next paper tip enters.

We have given an example of detection using a sensor as a way to determine timing, but as long as the paper feed program is easy, there is no need to be particular about the method using a sensor.

(Effects) According to the present invention, a member is provided that displaces the paper guide member disposed at the entrance of the fixing section to a paper guide position and a paper non-guide position above the entrance, and the member is moved at the timing of paper feeding. Since it is characterized by the following changes, it is possible to reliably guide curled paper 1 normal paper to the fixing roller, and it also prevents the rear end of the paper from coming into contact with the guide plate due to splashing up, thereby preventing image distortion. It never occurs.

[Brief explanation of the drawing]

FIG. 1 is a front view of the embodiment when the solenoid of the present invention is not activated;
Figure 2 is a side view of the main parts of Figure 1 when the solenoid is not activated, and Figure 3 is
The figures are a side view of the main part of the solenoid in FIG. 1 when it is in operation, FIG. 4 is a front view of the solenoid in FIG. 1 when it is in operation, and FIG. 5 is a front view of the conventional device. 1...Paper 2...Transport belt 3...Rear end detection sensor 4...Solenoid 6
... Paper guide plate 9 ... Fixing roller 1
1...pressure roller

Claims (1)

[Claims] The present invention is characterized by providing a member that displaces the paper guide member disposed at the entrance of the fixing section to a paper guide position and a paper non-guiding position above the entrance, and the member is changed in accordance with the timing of paper passing. Paper guide device of thermal roller fixing device.