JPS6246678Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a paper suction mechanism of a fixing device.

FIGS. 1 and 2 are diagrams showing a conventional suction shutter mechanism. That is, the position of the shutter 2, which moves reciprocally within the passage between the suction holes of the chamber divided into a plurality of chambers and the suction hose 4 corresponding to the paper width, is directly connected to the pulley to which the wire for moving the shutter is connected. The position of the encoder having several slits on the circumference is detected by an optical sensor 9, and control is performed so that the encoded paper width information and the encoder detection code match.
However, since an encoder, an optical sensor, etc. are used, there are drawbacks such as a large number of parts and high cost, and the optical sensor causes erroneous detection due to the influence of toner, paper powder, etc.

Another known method is to drive the shutter with a feed screw, but this method is not only heavy and expensive, but also has poor speed response, and requires a chamber each time to correct the shutter position due to wear of the screw. It had the disadvantage that it had to be disassembled.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, simplify the mechanism, and reduce costs.

This invention detects the reference position of the suction shutter using a magnetic detection element that is not affected by toner or paper dust, and also uses a stepping motor as the drive motor to determine the reference position of the shutter corresponding to the paper width. We devised a way to control the number of steps from the position.

FIGS. 3 and 4 show embodiments of the present invention.
That is, the magnet 1 embedded in the suction shutter
1 is detected by the magnetic detection element 10, and the position where the magnet and the magnetic detection element face each other becomes the reference position of the suction shutter. This position is the position when the printing paper used is the minimum width. When the width of the paper increases, the suction shutter moves to the left in the figure, and the stepping motor 6 rotates the pulley 7 and moves the shutter. For example, if the circumference of the pulley is 3 inches, and if paper is used that is 1 inch wider than the minimum width, it is sufficient to drive the pulley by the number of steps equivalent to 1/3 rotation, counterclockwise. . Because the suction shutter is pulled toward the suction hose 4 side due to the pressure difference between the chambers on the right and left side of the suction shutter, it is necessary to hold the stepping motor 6 in a chopping hold after the suction shutter is moved. be.

As mentioned above, in the pulley and wire shutter drive system, the present invention provides a magnet in the shutter itself and drives the pulley with a stepping motor in order to determine the reference position of the shutter in response to slips between the pulley and wire. By doing so, since feed control is always performed based on the actual position of the shutter, accurate control without errors such as wear is possible, and losses in the suction system can be eliminated. Furthermore, compared to the screw feed system, the mechanical drive system is simpler, the position control is simpler, and it is possible to provide a printing paper suction mechanism that is resistant to environments contaminated with toner, paper dust, and the like.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a conventional embodiment. FIG. 2 is a sectional view thereof. FIG. 3 is a plan view showing an embodiment of the present invention, and FIG. 4 is a side view thereof. In the figure, 1...printing paper, 2...suction shutter, 3...suction box, 4...suction hose, 5...wire, 6...drive motor,
7...Pulley, 8...Encoder disk, 9...
...Optical sensor, 10... Magnetic detection element, 11...
. . . Magnet, 12 . . . Stepping motor.

Claims (1)

[Scope of utility model registration request] A suction box consisting of one negative pressure chamber, a suction plate that covers the opening of this suction box and has many intake holes, and a pair of pulleys provided inside the suction box. The suction shutter is connected to a tensioned wire and moves back and forth within the suction box, and the suction shutter drive motor drives the pulley, and the suction shutter is configured to suck printing paper moving on the suction plate. In the fixing device, a toner image is fixed on the paper by applying a braking force to the paper and applying tension to the paper fed out by a heating pressure roller behind the suction plate.
A magnetic detection element is attached to the suction box, a magnet is attached to the suction shutter to detect the reference position of the shutter, and a stepping motor is used as the suction shutter drive motor to adjust the shutter according to the paper width. A printing paper suction mechanism characterized in that the position is controlled by the number of driving steps of the stepping motor.