JPS6019183A - Form peeling auxiliary device - Google Patents

Abstract

PURPOSE:To eliminate defect accompaied with the operation of a peeling auxiliary means without degrading peeling capacity by operating the form peeling auxiliary means when a form thinner than a prescribed value is detected by a form thickness detecting means. CONSTITUTION:The gap between resist rolls 41 and 41' is detected by elements 42 and 43 when a form passes between these rolls; and if the detected form thickness is smaller than a prescribed value, a form peeling auxiliary means 44 is operated by a signal from a control signal circuit 33 to conduct a solenoid 48 is energized, and a peeling pawl 26 is brought into contact with a heat roll 22 to peel the form surely. Since the peeling auxiliary means 44 is operated only when the form thickness is smaller than the prescribed value, troubles accompanied with the operation of the peeling auxiliary means are held down to a minimum without degrading the peeling capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paper separation assisting device for assisting in the separation of paper from a fixing heat roller in an image recording apparatus such as an electrophotographic copying machine.

Generally, an electrostatic latent image is formed on a charge retaining member such as an electrostatic recording medium or an electrophotographic photoreceptor, a powder toner is applied to the electrostatic latent image to form a toner image, and the toner image is transferred onto a sheet of paper. An image recording apparatus configured to fix a toner image by a heat roller fixing device after transferring the toner image to a toner image has been put into practical use as a transfer type electrostatic recording apparatus, an electrophotographic apparatus, or the like.

The heat roller fixing device used in such image recording devices usually has a hollow structure, has a built-in heater, and has a heat roller with a non-adhesive surface treated and a non-adhesive elastomer material. It consists of a pressure roller.

FIG. 1 is a diagram showing an example of an electrophotographic copying apparatus using such a heat roller fixing device. Referring to the figure, 1 is an electrophotographic photosensitive drum, 2 is a corona charger, 3 is a movable document table, 4 is a platen glass, 5 is a Haraman lamp, 6 is a reflector, 7 is a fiber lens array, 9 is the developing roller 8
10 is a transfer corona charger, 11 is a peeling corona charger, 12 is a paper cassette, 13 is a pickup roller, 14 is a register roller, 15 is a guide plate, 16 is a suction belt conveyance device, and 17 is a developing device having: Support shaft 1
8 is a pivoted paper peeling claw; 19 is a cleaning device equipped with a blade 20; 21 is a heat roller fixing device; 22 is a cleaning device equipped with a blade 20;
24 is a paper guide plate; 25 is a pressure roller pressed against the heat roller 22; 26 is a paper peeling claw disposed opposite to the surface of the heat roller 22; Reference numeral 28 indicates a temperature sensor for controlling the lighting of the heater lamp 23, 28 indicates a paper ejection roller, and 29 indicates an image leading end static eliminator comprising a lamp and the like.

In an electrophotographic copying device made of these components,
While rotating the photoreceptor drum 1 in the direction of the arrow, the corona charger 2 is operated to uniformly charge the platen glass 4.
The original placed thereon is irradiated by the lamp 5, and its optical image is projected onto the photosensitive drum 1 via the lens array 7 to form an electrostatic latent image. The developing roller 8
A toner image is formed by applying toner to the
This toner image is superimposed on the paper fed from the paper cassette 12 at the position of the transfer corona charger 10 and is transferred onto the paper. Then, in order to remove the attraction force between the paper and the photosensitive drum 1 due to the charging of the paper during the transfer,
The corona charger 11 for peeling is activated to peel the paper from the drum 1. The peeled paper is transferred to the suction belt conveyor 16
The photosensitive drum 1 is sent to a fixing device 21, and a cleaning device 19 removes toner remaining after the transfer from the photosensitive drum 1 in preparation for the next image forming process.

By the way, one of the problems that occurs in a heat roller fixing device applied to an image recording device such as an electrophotographic copying device is the development of poor peeling of the paper. When this paper peeling failure occurs, the paper gets caught up in the heat roller 22, and it is not easy to remove it.
In some cases, the heat roller 22 may be damaged. For this reason, conventionally, the hollow heat roller 22 and pressure roller 25 constituting the heat roller fixing device 21 have been made of non-adhesive materials or have been surface-treated to prevent toner from adhering to the paper. In general, a peeling claw 26 is provided to further prevent paper from becoming entangled.
is attached, and a guide plate 24 which also serves to prevent entrainment is arranged on the pressure roller 25 side. However, the peeling claw 26 used to peel the paper from the heat roller 22 causes fine scratches on the heat roller 22 and causes toner adhesion, and when this toner adhesion occurs, it prevents the paper from being peeled off. Otherwise, the heat roller 22 has the disadvantage of causing toner off-cent, thereby reducing the durability life of the heat roller 22.

Even if such a peeling claw 26 is provided, if the leading edge of the paper is not peeled off from the heat roller 22 even slightly, the action of the peeling claw 26 will be uncertain; The adsorption force generated between -22 and 22 mainly depends on the adhesive force generated when the toner is melted, so the charge is removed from the leading edge of the image using the static eliminator 29 to prevent toner from adhering to the leading edge of the paper. In general, a structure is used to ensure that peeling is performed.

Since this means does not generate adhesive force to the heat roller at the leading edge of the paper, it has an extremely large effect of promoting peeling. However, on the other hand, this has the disadvantage that an image cannot be formed on the entire surface of the paper, and the leading edge of the image may be missing.

It is still known to apply a release agent such as oil to a heated roller to promote paper separation, but if the oil applicator is kept in constant contact with the heated roller, the oil will be consumed. Not only that, but the oil evaporates and condenses in various parts of the aircraft, causing contamination.

Conventionally, several measures have been proposed to eliminate the drawbacks of these paper peeling assist devices. For example,
In Publication No. 63044, etc., the contact time between the peeling claw and the heat roller is reduced by configuring the peeling claw to be kept away from the heat roller at all times and to be placed in the operating position by detecting paper feeding. Techniques have been shown to shorten and prevent thermal roller deterioration. However, although this technique is expected to improve the life of the roller by reducing the contact time between the peeling claw and the hot roller, the effect is within that range and cannot be said to be sufficient. Furthermore, there is also a known technique for applying the release agent in synchronization with the conveyance of the paper, but although this can provide some effect in reducing the application time, it is not sufficient. do not have. Note that there is no known improvement technique for the method of forming a non-image area at the leading edge of the paper for the purpose of assisting paper separation.

The present invention was made in order to eliminate the drawbacks of paper peeling auxiliary devices of conventional image recording devices, and provides a paper peeling auxiliary device that minimizes the occurrence of various defects associated with the operation of the paper peeling auxiliary device. The purpose is to provide

As mentioned above, the basic acting force that causes paper to peel off from the heated roller is generally due to the difference between the elastic force of the paper to maintain its flatness and the adhesive force of the molten toner to the heated roller. It is something. If we assume that paper is an ideal elastic body, the force required to bend it will be proportional to the cube of its thickness, and there is a strong correlation between paper thickness and releasability. be. Therefore, in the case of relatively thick paper, the elastic force is large enough to overcome the adhesive force, and peeling can be performed without using special peeling aid means. On the other hand, in the case of relatively thin paper such as air mail paper, the elasticity of the paper is weak, so peeling aids such as forming a non-image area at the leading edge of the paper or installing a peeling claw are necessary. Without this means, it is almost impossible to remove the paper.

In conventional image recording apparatuses, the operation of the peeling auxiliary means is determined based on the conditions of the thinnest sheet of paper to be applied. The present invention has focused on this point, and the present invention has been developed to appropriately operate the peeling auxiliary means in accordance with the thickness of the paper, thereby eliminating the need for deterioration in peeling performance. This will greatly improve the deficiencies.

The present invention will be explained in detail below. FIG. 2 is a schematic configuration diagram for explaining the principle of the paper peeling auxiliary device according to the present invention, and portions with the same reference numerals as in FIG. 1 indicate the same members.

In FIG. 2, reference numeral 31 denotes paper thickness detecting means, which is arranged along the paper path, but its position is limited in relation to the installation location of the paper peeling assisting means. For example, if the paper peeling auxiliary means is provided attached to the heat roller fixing device 21, the paper thickness detection means 31 can be arranged along the paper path from the paper cassette to the heat roller fixing device 21. On the other hand, when the peeling auxiliary means is arranged in relation to the photosensitive drum 1, the paper thickness detection means 31 needs to be arranged at a position upstream of the transfer corona charger 10 and close to the paper cassette.

Reference numeral 32 denotes a paper thickness detection circuit which receives a detection signal from the paper thickness detection means 31, amplifies and shapes it, and sends out a signal corresponding to the paper thickness. Reference numeral 33 denotes a peeling auxiliary means control signal circuit, which receives the paper thickness signal from the paper thickness detection circuit 32 and compares it with a reference signal to form a control signal for the peeling auxiliary means; It receives a timing signal from a sequence control circuit 34 that controls the control signal, and also controls the timing of forming and transmitting the control signal. It is necessary to form this control signal when the paper reaches the placement position of the paper thickness detection means 31, and since the paper peeling auxiliary means has an effective timing as described later, both If the timings do not match, it is necessary to store the detection signal or delay the control signal and send it out at a predetermined timing, and these timings can be obtained by the signal from the sequence control circuit 34. can.

Reference numeral 35 denotes a peeling auxiliary means driving circuit, which receives a control signal from the control signal circuit 33 and drives an operating member attached to the peeling auxiliary means 36, such as a solenoid or a lamp. The peeling assisting means 36 has a function of assisting the sheet to be peeled off from the heat roller 22, and is configured to include an operating member that controls the function and operation of the peeling assisting means 36. As mentioned above, the stripping aid 36
Examples include a mechanism such as a peeling claw 26 and a solenoid for bringing it into contact with and separating from the heat roller 22, or a static eliminator 29 such as a high-speed responsive static eliminator lamp for forming a non-image area at the leading edge of the paper. These include an oil vat or roller that applies a release agent to the heat roller, and a mechanism that brings it into contact with and away from the heat roller 22.

By configuring the paper peeling auxiliary device in this way, the paper peeling auxiliary means can be operated appropriately in accordance with the thickness of the paper, and the adverse effects caused thereby can be minimized. That is, if the thickness of the paper detected by the paper thickness detection means 31 is thicker than a predetermined value and no peeling assistance is required, no control signal is sent from the control signal circuit 33, and therefore the paper peeling assistance means 36 is not activated. There are no harmful effects caused by the operation. On the other hand, if the paper thickness is thinner than the predetermined value, a control signal is sent from the control signal circuit 33, the paper peeling auxiliary means 36 is operated, and the paper is peeled off smoothly in the heat roller fixing device 21. In this case, although the operation of the peeling auxiliary means 36 causes a problem, since the peeling auxiliary means 36 operates only in special cases, the problem is extremely rare.

FIG. 3 is a schematic configuration diagram showing an example of a specific embodiment of the paper peeling auxiliary device according to the present invention. In Figure 3,
Reference numeral 31 denotes paper thickness detection means, but as will be described later, various configurations are applicable. A configuration is shown in which the gap between them is detected and measured by a radiant energy sending element 42 and a radiant energy detecting element 43. The configuration and operation of the paper thickness detection circuit 32, the peeling auxiliary means control signal circuit 33, the sequence control circuit 34, and the peeling auxiliary means driving circuit 35 are the same as those shown in the principle diagram of FIG.

Reference numeral 44 denotes a drive device for the peeling claw 26, which is a paper peeling auxiliary means. The peeling claw 26 that comes into contact with and separates from the fixing heat roller 22 is attached to the support shaft 45 via a buffer means such as a spring (not shown). 46 has one end connected to the support shaft 45
It is a lever fixedly attached to the lever, and a pin 47 is implanted at the other end. 48 is an electromagnetic solenoid, and 49 is its actuator, which is engaged with the pin 47.

The actuator 49 is normally urged upward by a spring 5o, and is configured so that by rotating the lever 46 counterclockwise, the peeling claw 26 takes a position away from the heat roller 22.

When the solenoid 48 is energized, the actuator 49 is attracted against the spring 50, and the lever 46 is rotated clockwise, causing the peeling claw 26 to come into contact with the heat roller 22 and peel it off. It is activated as an auxiliary means. Peeling claw 26
must be in contact with the heat roller 22 with moderate pressure,
For this reason, it is preferable that the peeling claw 26 and the support shaft 45 are connected to each other through a buffer means such as a spring, as described above.

If the peeling claw 26 is constantly in contact with the heat roller 22, there is a risk of damaging and deteriorating its surface. However, in this embodiment of the present invention, the paper thickness detected by the measuring means 31 is
Only if the drive circuit 35 is thinner than a predetermined level.
The solenoid 48 is actuated by a drive signal to place the peeling claw 26 in an operating state, thereby minimizing damage to the heat roller 22.

FIG. 4 is a schematic configuration diagram showing a second embodiment of the present invention. This embodiment is the same as the embodiment shown in FIG. 3, but is further provided with a static eliminator 29 for forming a non-image area at the leading edge of the paper. It can also be configured to only control the device 29.

In an image recording device equipped with a conventional thermal roller fixing device, the non-image area at the leading edge of the paper is determined so that it can be stably peeled off from the fixing heat roller for the thinnest paper to be applied. There is.

Therefore, it can be said that this non-image area is unnecessarily wide for sheets of paper that are normally used in large quantities. On the other hand, in an apparatus in which the non-image area is set narrowly, the lower limit of the paper thickness to be applied is set to a large value, which has the disadvantage that the applicable range of paper is narrow.

In this embodiment of the present invention, the non-image area at the leading edge of the paper is determined in accordance with the paper thickness, and the non-image area is usually not formed or is extremely small, and when thin paper is used. The above-mentioned unreasonableness is solved by configuring the image forming apparatus to form a wide non-image area.

In FIG. 4, the paper thickness detection means 31, paper thickness detection circuit 32, peeling auxiliary means control signal circuit 33, sequence control circuit 34, peeling auxiliary means driving circuit 35, and peeling claw driving device 44 are shown in FIG. 2 or 3. It has a similar configuration to that shown in . Reference numeral 35' denotes a single-stage stripping auxiliary element drive circuit which receives a control signal from the control signal circuit 33 and controls the operation of the static eliminator 29. In order to accurately eliminate the latent image on the charge retaining member corresponding to the leading edge of the paper,
It is desirable that the charge retaining member is a photoreceptor, and therefore, the present invention is suitably applied to an electrophotographic recording device, and this embodiment shows an example of this application.

In order to erase the latent image on the electrophotographic photoreceptor 1, it is possible to erase it with light. Therefore, a fast-responsive light source such as an LED lamp or a discharge lamp is used as the static eliminator 29.
The configuration for controlling the lighting is simple and preferable.

Alternatively, a high-speed shutter such as a liquid crystal display or shutter may be arranged in front of the continuously lit lamp to control the shutter.

In electrophotographic recording devices, a trimming lamp is often installed in order to remove the charge in the non-image area and prevent unnecessary toner consumption. It is even more suitable if the separation assisting means of the present invention is controlled based on the above-described structure so that it also functions as a static eliminator.

It is most preferable that the width of the non-image area formed at the leading edge of the paper is continuously variable in accordance with the detected paper thickness. It may be configured to obtain only two states,
Even in that case, the effects of implementation are significant.

Note that, as in the embodiment shown in FIG. The electrostatic latent image portion corresponding to is the static eliminator 2.
Therefore, the position of the static eliminator 29 is restricted in this respect.

Although paper thickness detection means based on a certain operating principle are conventionally known, not all of them are suitably applied to the present invention. For example, there is a known technology that detects paper thickness by mechanically magnifying the displacement of the rollers that occurs when paper is wedged in a pair of rollers placed in the paper transport path, and prevents double feeding of paper. However, mechanical enlarging mechanisms are prone to errors, and although they can be applied to detect large thickness variations such as double-feed detection, unless the mechanism is extremely sophisticated, the method of the present invention will not work. This method is unsuitable for devices that require delicate paper thickness detection information. Furthermore, a technique for obtaining paper thickness information by measuring the optical transmittance of paper is also known, but since the transmittance varies greatly depending on the quality of the paper, there is a high risk of malfunction.

One example of paper thickness detection means suitable for the present invention is to non-contactly detect the gap between the rollers that is formed when the paper is gripped by a pair of rollers disposed in the paper transport path using the amount of radiant energy that passes through the roller pair. It is a means of measurement.

The radiant energy used to detect the size of the gap between the rollers can be electromagnetic waves represented by visible light, ultraviolet light, infrared light, etc., or elastic waves using air as a propagation medium such as sound waves or ultrasonic waves. You can use it.

Figures 5-5 (0) are diagrams showing an example of a paper thickness detection means based on the principle of detecting paper thickness by measuring the inter-roller gannog using light, and 51.51' is a paper transport roller. 52 is a light source lamp, and 53 is a light receiver. These light source lamps and light receivers 52 and 53 are arranged adjacent to the paper path so as not to interfere with the paper path.

FIG. 5 (5) shows a state in which the paper is not gripped by the pair of rollers 51, 51', and the light emitted from the light source lamp 52 is blocked by the pair of rollers 51, 51', In this state, no detection signal is generated. Figure 5 (
13) shows a thin sheet of paper 54 being held between the pair of rollers 51, 51', and a small amount of light passes through the small gap between the rollers to the receiver 53.
, and a small detection signal is obtained.

In FIG. 5(C), the thick paper 55 is attached to the roller pair 51.51.
', a large inter-roller gap is formed, and as a result, a large detection signal is obtained from the light receiver 53.

The paper thickness measurement using the detection means shown in Figure 5 (5) to (0) is a non-contact measurement, and if you want to increase the detection output, you just need to make the light source lamp brighter, which increases the S/N ratio. It is also possible to perform highly accurate and reliable paper thickness detection, and is suitable for the present invention.

FIGS. 6(5) to 6(C) are diagrams showing other configuration examples of paper thickness detection means using radiant energy. This detection means utilizes elastic waves such as sound waves and ultrasonic waves that use air as a propagation medium. In the figure, 61 and 61' are a pair of rollers such as register rollers arranged in the paper conveyance path, 62 is an elastic wave transmitter, and 63 is an elastic wave receiver. Oscillator, receiver 6
3, a microphone, an ultrasonic receiver, etc. are used.

FIG. 6 (5) shows a state in which no paper is held in the pair of rollers 61, 61', and the elastic wave energy sent out from the wave transmitter 62 is intercepted by the pair of rollers 61, 61' and received. This shows a state in which the signal does not reach the receiver 63 and no detection signal is generated from the receiver 63. FIG. 6 (I3) shows a state in which a thin sheet of paper is held in the pair of rollers 61, 61' and a small canopy t1 is formed, and in this state there is a gap t1 from the transmitter 62'fJ. Through this, a small amount of elastic wave energy reaches the receiver 63 and a small detection signal is generated. Figure 6 (01 is the roller pair 61.61
A thick sheet of paper is held in the gap t2, resulting in a large gap t2, and a large amount of elastic wave energy reaches the receiver 63 through this gap t2, resulting in a large detection signal.

As described above, the paper thickness detection means shown in FIG. 6 4-(0) has high accuracy and stable operation like the detection means shown in FIG. 5 (5)-(q). It is suitable for the present invention. In particular, this detection means using elastic waves is less affected by dirt on the roller pair and dirt on the transducer, and can operate stably over a long period of time. (It is superior to the optical detection means shown in C1.

As explained in each of the above embodiments, the present invention controls the operation of the paper peeling auxiliary means based on the paper thickness detection information, so that the paper can be easily and reliably peeled from the fixing heat roller. However, it would be more effective to configure the system to not only control paper peeling from the heat roller but also control other elements based on the paper thickness signal from the same paper thickness detection means. . For example, a configuration in which the heating temperature setting of the heat roller fixing device is controlled and changed in accordance with the paper thickness is an example of a suitable combination. In this case, when the paper thickness is thin, a low fixing temperature setting is used. By configuring automatic control based on the paper thickness detection signal to increase the fixing temperature setting when the paper is thick, the optimum heating temperature of the fixing device can be automatically set according to the paper thickness. I can do it.

As described above in detail based on the embodiments, the present invention includes:
comprising a paper peeling auxiliary means for assisting the peeling of the paper from the heat roller of the heat roller fixing device, and a paper thickness detection means,
When the detection means detects paper thickness thinner than a predetermined value,
Since the paper peeling auxiliary means is configured to operate, the paper is reliably peeled from the heat roller, and the adverse effects that occur due to the operation of the paper peeling auxiliary means can be minimized. The paper peeling auxiliary means is composed of a peeling claw that can freely come into contact with and separate from the fixing heat roller, and when the paper thickness detecting means detects a paper thickness thinner than a predetermined value, the peeling claw is brought into contact with the fixing heat roller. By configuring it like this, the storyteller school≠畦→
In a state where peeling assistance by the peeling claw is required, its operation can be ensured, and deterioration of the fixing heat roller due to the peeling claw can be minimized.

Furthermore, a static eliminator is provided for removing charge from the leading end of the electrostatic latent image formed on the charge retaining member, and the static eliminator is configured to:
By configuring the paper thickness detection means to be activated when the paper thickness is detected to be thinner than a predetermined value, it is possible to reliably form a non-image area on paper that requires the formation of a non-image area at the leading edge of the paper. In addition to forming and providing an auxiliary peeling effect,
For paper sheets that are thicker than a predetermined value, an image without screen defects can be formed.

In addition, by configuring the paper thickness detection means with a radiant energy sending element and a radiant energy detection element that are arranged adjacent to the paper path of the pair of paper transport rollers, the paper thickness can be detected with high precision and reliability. Effects such as being able to properly operate the peeling auxiliary means depending on the conditions can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an electrophotographic copying apparatus using a conventional heat roller fixing device, FIG. 2 is a schematic configuration diagram for explaining the principle of a paper peeling auxiliary device according to the present invention, and FIG. 3 is a schematic diagram of one embodiment of the present invention, FIG. 4 is a schematic diagram of another embodiment of the present invention, and FIGS. FIGS. 6(5) to 6(C), which are diagrams illustrating the operation mode of one configuration example of the paper thickness detection means, are also diagrams illustrating the operation mode of another configuration example of the paper thickness detection unit. In the figure, 11l is a photosensitive drum, 10 is a corona charger for transfer, 21 is a heat roller fixing device, 22 is a heat roller for fixing, 25 is a pressure roller, 26 is a peeling claw, and 29 is an image leading edge static eliminator. , 41 and 41' are a pair of register rollers, 42 is a radiant energy sending element, 43 is a radiant energy detecting element, 44 is a peeling claw drive device, 48 is an electromagnetic solenoid, 52 is a light source lamp, 53 is a light receiver, and 62 is a wave transmitter. 63 indicates a receiver. Patent applicant Olympus Optical Industry Co., Ltd. Figure 5 (A) (B) (C) b1' Figure 6 (A) (B) (C) 61'61-61'

Claims (4)

[Claims] (1) An image recording device configured to apply toner to an electrostatic latent image formed on a charge retaining member, transfer the formed toner image onto paper, and fix the toner image by a heat roller fixing device after transfer. In the present invention, a paper peeling auxiliary means having a function of assisting the peeling of the paper from the fixing heat roller of the heat roller fixing device, and a paper thickness detection means disposed along the paper conveyance path on the upstream side of the heat roller fixing device are provided. A paper peeling auxiliary device comprising: a paper peeling auxiliary device configured to operate the paper peeling auxiliary means when the paper thickness detecting means detects a paper thickness thinner than a predetermined value. (2) The paper peeling auxiliary device according to claim 1, wherein the paper peeling auxiliary means is constituted by a peeling claw that is held in a detachable manner from a fixing heat roller. (3) The paper peeling auxiliary means is constituted by a static eliminator that removes the charge from the leading edge of the electrostatic latent image formed on the charge holding member.
Paper peeling auxiliary device described in Section 2. (4) The paper thickness detection means includes a pair of paper transport rollers;
2. The paper peeling auxiliary device according to claim 1, comprising a radiant energy sending element and a radiant energy detecting element, which are arranged adjacent to the paper path of the pair of paper transport rollers.