JPS616675A - Rotary driving device - Google Patents

Abstract

PURPOSE:To prolong the life of a couple of rollers and obtain a stable rotary state by providing an abutting pressure control means which decreases or eliminates the abutting pressure of a coule of rollers according to an increase in driving torque. CONSTITUTION:When a DC motor 7 increases in its rotary torque, the quantity of a current to the motor which is detected by an ammeter 23 increases so as to hold the rotaion of the motor constant. For the purpose, reference values A-C (A>B>C) for the amount of the current are set and the control means 22 is so programmed previously so that an input power source is turned off above A to stop the rotation of the motor and an electromagnetic clutch 21 is turned on when the amount of the current is between A and B. At this time, the electromagnetic clutch 21 is turned on with microswitches 18 and 20 which are operated by stop cams 17 and 19. Consequently, the roller couple are separated so that their abutting pressure is decreased or eliminated, and consequently an unreasnable force to the rollers is reduced or eliminated, thereby prolonging the life of the roller.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The invention relates to an apparatus having at least one pair of rollers and for rotationally driving these rollers.

Among these devices, a fixing device that uses a pair of rollers as a roller for fixing a toner image on a recording material is particularly effective in this field because it can solve problems peculiar to non-exploding aAFi fixing.

Furthermore, among these devices, the invention is particularly effective in devices in which one of a pair of rollers is a ceramic roller, since problems specific to ceramic rollers can be solved.

(Prior Art) Conventionally, various rotary drive devices bring pairs of rollers into pressure contact, and use the pressure between the roller pairs to convey or process a member passing between the rollers, or to coat or process a member passing between the rollers. We are removing unnecessary items, etc. In any case, what is required of these roller pairs is to obtain stable rotation over a long period of time.

However, if something gets between these rollers for some reason, the roller drive torque increases significantly, causing distortion in the layers and core metal etc. that make up the roller itself.
Rotation is blocked, leading to a number of problems, such as poor conveyance and destruction of the roller itself.

In addition, countermeasures have been taken to ensure stable roller rotation even when the drive torque increases, such as using a DC motor and forcing both rollers to rotate, but the configuration of the roller itself is limited to rigid rollers. In addition to this, the problem of plastic deformation of the roller itself remains unsolved.

From another point of view, in a fixing device used in an image recording device, fixing rollers such as a cleaning roller, a coating roller, and a fixing roller that conveys the recording material under pressure are often used.
For this purpose, fixing rollers that come into pressure contact with each other have a multilayer structure or a complicated structure. In the fixing device, a member such as a recording material or a clip is interposed between the fixing rollers, and the roller driving torque increases significantly, which may impede the rotation of the rollers.

In such cases, conventional methods have been used to determine the jam by looking at the passage time of the recording material and stop or release the pressure on the roller pair, but by the time countermeasures are taken, a large amount of stress is applied to the rollers. Therefore, the reality is that the life of the roller is shortened.

This problem is particularly serious in devices that fix toner images on recording materials under pressure.

From another perspective, when a ceramic roller is used as one of a pair of rollers used in a rotary drive device, the advantages of ceramics, namely its light weight, hardness, and resistance to bending (
(compared to steel), and the increased driving torque causes cracks and cracks, making it impossible to put it into practical use.

In particular, it is difficult to put into practical use a pressure fixing device using a ceramic roller as a fixing roller or a heating roller fixing device using a ceramic roller having PTC characteristics because the roller becomes unused when a jam occurs.

(Objective) An object of the invention is to provide a rotational drive device that can prolong the life of the roller and provide a stable rotational state.

Another object of the invention is to provide a rotary drive device that solves problems in the fusing field, allowing stable use of a fusing roller used in a fusing surface.

Another object of the invention is to provide a rotary drive device which makes it possible to put ceramic rollers into practical use.

(Summary of the Invention) In order to achieve the above-mentioned object, the present invention provides a common configuration that reduces or eliminates the contact pressure of the pair of rollers in response to an increase in the driving torque for rotationally driving one of the pair of rollers. It is characterized by having contact pressure control means.

Since the impact on the roller can be reduced and the load during rotation can be reduced, the service life of the roller can be increased.

In particular, when applied to a fusing device, a pair of fixing rollers makes it easy to take out the recording material, and when applied to a ceramic roller, the advantages of the roller can be put to practical use.

(Explanation of Examples) In the following, the examples of non-inventions are applied to fixing devices, but the scope of application of non-inventions includes everything that is used to solve problems from the viewpoint of 1- above. .

Figure 1 is a schematic sectional view of the non-inventive embodiment seen from the front;
The figure is a schematic side view from the cam 11 side in FIG. 1, FIG. 5 is an explanatory diagram of the drive transmission and contact pressure control in FIG. 1, and FIG. 4 is a flowchart showing the main configuration of the invention.

The embodiment shown in FIG. 1 is an embodiment of a pressure fixing device in which a ceramic roller is used as the pressure fixing roller which provides the most effective and excellent effect. 1 shows a state in which the pressure fixing rollers 1 and 2 are separated, and FIG. 2 shows a state in which the rollers 1 and 2 are pressed against each other.

Samples 1 and 2 were manufactured by bonding a ceramic vibrator onto a shaft made of a metal core using a pressure fixing roller. The roller 1 is connected to the left and right side plates 3 via bearings 4, 42.
．． ．． It is rotatably supported by 52. The roller 2 is rotatably supported by the left and right pressure arms 15 via bearings 61 and 62, as shown in FIG. The roller 1 is engaged with a gear 8 directly connected to a DC motor 7 via a gear 5 fixed to the end of the roller 1, and is rotationally driven by these movements. The roller 2 normally rotates due to the frictional force from the roller 1, but the pressure contact state is controlled. This control is performed by transmitting the rotation of the DC motor 7 to the pressure arm 13 via an electromagnetic clutch (see FIG. 3). Specifically, the eccentric cam 11 is attached to one end and the gear 1 is attached to the other end.
When the electromagnetic clutch 21 is turned on to the operating shaft 9 having a rotational speed of 0, the rotational force of the DC motor is transmitted through the gear 10. As a result, the eccentric cam 11 rotates, and the pressure arm
The roller 2 moves upward and downward to bring the roller 2 into pressure contact with the roller 1. In an unusual case, when the eccentric cam 11 is as shown in FIG. 1, the rollers 1 and 2 are separated, and when the eccentric cam 11' is as shown in FIG. 2, the rollers 1 and 2 are pressed against each other.

12 is a roller and is rotatably fixed to the pressure arm. Furthermore, a stop cam 17, 19 and a micro switch 18, 20 for operating the electromagnetic clutch 22 are provided on one operating shaft 9, with a 180° offset from each other.

m', when the source is turned on and the copy button is turned on, D
As the C motor rotates, the electromagnetic clutch circuit is turned on and its drive rotates the pressurizing cam 11 via the gear 10, and the pressurizing arm 13 is held on the support shaft until its large diameter portion comes into contact with the roller 12. 14, the roller 2 together with the bearing 62 is pushed upward by the spring 15 and brought into pressure contact with the roller 1. The rotation of the pressure cam 11 at this time is also transmitted to the stop cam 17 attached to the same operating shaft 9, and by actuating the micro switch 18, the electromagnetic clutch is turned off and the rotation of the operating shaft is stopped. , to maintain the pressurized state. Therefore, the rollers 1 and 2 rotate while being pressed against each other, and the paper P carrying the conveyed unfixed image T is fixed under pressure.

When copying is completed, the paper P is ejected and before the DC motor 7 stops, the electromagnetic clutch 21 is turned on again and the pressure cam 11 rotates until it reaches the small diameter portion (Fig. 1) for about 18 seconds.
Rotate it by 0°, actuate the stop cam 19, actuate the micro switch 20, and turn off the electromagnetic clutch 27.

Here, due to the weight of the roller 2 and the release of the compressive energy of the spring 16, the roller 1. Roller 2 is spaced y11 apart.

When the rotational torque of the DC motor 7 increases, the ammeter 23 uses this to keep the rotation of the DC motor constant, so that the amount of current flowing to the motor increases. Therefore, the standard value of this amount of current is set in advance as A, Bc (A) El>c), and when it is A or more, the input power is turned off, and the rotation of the L motor is stopped. The control means 22iC may be programmed in advance to turn on the clutch 21. At this time, the electromagnetic clutch 21 is activated by the microswitch 1 operated by the stop cam 17.19.
It is set to be turned off by 8.20. It is preferable that the reference value C of the current value is set to be equal to or slightly higher than the maximum value under normal operation, and to be much smaller than the load that would cause the roller to stop in the event of a jam.

As a result, even if recording material jams in the fixing section including the pressure contact section, or recording material thicker than the designed value enters, the drive torque of the motor can be adjusted directly or directly before a dangerous load is applied to the roller. Corresponding data is detected and the contact pressure between the pair of rollers can be reduced or brought to a state where they are no longer separated before the torque increases dangerously.

Therefore, excessive force on the roller can be reduced or eliminated, and the life of the roller can be greatly improved.

Further, the increase/decrease in the driving torque may be detected by detecting the rotation speed of an encoder attached to the roller shaft and a light detection means. The reference value for reducing or eliminating the contact pressure depends on the detection method, but it must be greater than the maximum torque in normal rotational drive or a signal equivalent to this, and between a dangerous torque or a signal equivalent to this button. It is more preferable that the magnitude is good and the value is close to the maximum torque or a signal corresponding thereto.

The flowchart in FIG. 4 shows the flow of an embodiment according to the invention.

A pair of rollers is driven and pressed by a start signal from a main switch or a copy switch (step 25). As the λ roller rotates, the roller drive torque or a signal equivalent to it is detected (step 26).Only one roller When the roller is a ceramic roller, it is better to detect the driving torque of this roller or a signal corresponding to this.

This detection continues during the rotation of the roller, and the detection signal is constantly compared with a reference value (limit value for reducing the contact pressure) by means for controlling the contact pressure (control means 22 in FIG. 3). (Step 27).

As a result, when the detection signal is within the reference value (the equal sign may be omitted), stable driving is determined. However, when the detection signal exceeds the reference value (an equal sign may be included),
The contact pressure of the rollers in the pressed state is reduced or no pressure is applied (no pressure is removed by separating them) to reduce the torque required for driving (step 28).
, stop driving the rollers as necessary (step 29
).

After that, when a jam reset or other reset signal is input (step 30), the process is fed back to step 25 and the above flow is repeated.

By controlling in this way, each of the problems raised in the prior art can be solved, and in particular, in the fixing device, damage to the rollers can be eliminated and jam processing, other coating processing, and cleaning processing can be maintained for a long period of time.

In any case, the invention expands the selection range of materials and configurations required for the roller, and can significantly improve the life and usage time of the roller.

The invention is not limited to the embodiments described above, but may be such that the pair of rollers is always kept in pressure contact and the pressure contact is released only when the driving torque increases.

Furthermore, the ceramic roller is not limited to a structure for a pressure fixing device (it may also be a heating roller with PTO characteristics. Furthermore, it does not need to be a pair of ceramic rollers, but can be a pair of a ceramic roller and an elastic roller. You can.

The invention can be widely applied to a pair of pressing rollers provided in an apparatus.

[Brief explanation of the drawing]

Figure 1 is a schematic sectional view of the embodiment of the present invention seen from the front;
1 is a schematic side view from the cam 11 side in FIG. 1, FIG. 3 is an explanatory diagram of the drive transmission and contact pressure control in FIG. 1, and FIG. 4 is a flowchart showing the main configuration of the invention. 1.2...Pressure fixing roller 7...Do motor 11-...Eccentric cam 21...'Magnetic clutch 22...Control means 23...Ammeter Fig. 4

Claims (3)

[Claims] (1) at least one pair of rollers, a drive means for rotating the pair of rollers against each other, and reducing or reducing the contact pressure of the pair of rollers in response to an increase in the driving torque for rotationally driving one of the pair of rollers; A rotary drive device comprising: a contact pressure control means for reducing the contact pressure to zero; (2) The rotary drive device according to claim 1, wherein the pair of rollers are fixing rollers used in a fixing device that fixes a toner image on a recording material. (3) The rotational drive device according to claim 1 or 2, wherein one of the pair of rollers is a ceramic roller.