JPS5935022B2 - Fusing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device including means for applying an anti-offset liquid to a fixing roller to prevent offset.
More specifically, the present invention relates to a fixing device that controls the amount of anti-offset liquid applied based on a detection signal that is correlated with the amount of toner adhered to a copying material as a member to be fixed.

Conventionally, in a heat fixing device using a pair of fixing rollers, a heat roller is used to fix a toner image on a copying material.
In order to improve mold releasability, an anti-offset liquid such as silicone oil is applied.

The necessity of applying this anti-offset liquid is especially great when fixing multicolor toner images in a color copying machine.

This is because the amount of toner deposited is generally larger than that of a monochromatic toner image, and because multicolor toner images require sufficient heating during fixing to completely mix colors, offset to the heating roller is likely to occur. Therefore, when fixing a multicolor toner image, it is necessary to apply a larger amount of anti-offset liquid than when fixing a monochrome toner image.

However, when silicone oil is used as the anti-offset liquid, there is a problem that the silicone oil is expensive, and when a silicone rubber coating is used for the fixing roller, a large amount of silicone oil accelerates the swelling of the silicone rubber coating. . In view of the above, the present invention provides an apparatus that always applies an appropriate amount of anti-offset liquid when fixing either a multicolor toner image or a single color toner image.

In order to achieve the above object, the present invention provides a fixing device including a fixing roller for fixing a toner image on a fixing target member, and means for applying an offset prevention liquid to the fixing roller. means for controlling the amount of anti-offset liquid applied to the fixing roller by the anti-offset liquid application means so as to increase when the amount of toner adhering to the member to be fixed is large, in accordance with a detection signal having a correlation with the amount of toner adhering; A fixing device characterized by having: That is, the amount of anti-offset liquid applied during fixing is controlled based on a detection signal that is correlated with the amount of toner adhering to the member to be fixed. Here, automatic toner replenishment (AT
R) Known detection signals used for control, such as original density detection means, latent image potential detection means on photoreceptor, developer concentration detection means, developed image density detection means on photoreceptor, image density detection on copying material Detection signals from various detection means can be used, such as detection means. However, in consideration of ease of detection, cost of the detection device, etc., it is preferable to use a detection signal from a means for detecting document density or a means for detecting developer density. However, if a detection means for ATR control is already provided, a part of the toner concentration detection signal may be used, so the detection means is not particularly limited. The details of the present invention will be explained below using specific examples with reference to the drawings.

FIG. 1 shows a color electrophotographic copying machine capable of making monochrome and multicolor copies to which the present invention is applied.

In the illustrated example, an NP type photosensitive drum 1 is used.
The original placed on the original table glass 2 is illuminated by the illumination lamp 3, and the reflected light is reflected from mirrors 4, 5, lens 6, mirror 7, blue 81, green 82, red 83, which are switched according to the color separation. The AC
The photosensitive drum 1 is exposed to light through the static eliminator 10. The illumination lamp 3 and mirrors 4 and 5 in the optical system move to positions 32, 47 and 5', respectively, in synchronization with the rotation of the photosensitive drum 1. The photosensitive drum 1 is cleaned by a cleaning blade 11, charged by a primary charger 12, and charged by an AC static eliminator 1.
0, static electricity removal is performed at the same time as exposure. Next, the entire surface of the photosensitive drum 1 is exposed to light from 13 light sources, and yellow 14
,, magenta 142, cyan 143 and black 144
The image is developed by one of the developing devices 14. The reflective density of the developer is detected on the periphery of the end of the developing sleeve in each developing device (when the toner is consumed by development, the developer is colored in the carrier color (for example, in Nippon Seifun EFV, the dark blue color is dominant). In other words, the reflection density of the developer increases.) A detection means (for example, see Utility Model Application Publication No. 49-84031) and a hopper for replenishing toner according to the detection signal are connected to each developer. (not shown). On the other hand, transfer paper 15
is sent out by a delivery roller 16 and held by a gripper 18 of a corona transfer unit 17.

Next, the transfer paper 1 is inserted between the transfer charger 19 and the photosensitive drum 1.
5, the toner image on the photosensitive drum 1 is transferred onto the transfer paper 15. While holding the transfer paper 15, the gripper 18 rotates three times in the case of full-color copying, twice in the case of two-color copying, and once in the case of single-color copying.
The toner image on the photoreceptor 1 is transferred onto the transfer paper 15. After the transfer is completed, the transfer paper 15 is released from the gripper 18, guided to the conveyor belt 21 by the operation of the separating claws 20, and further to the roller fixing device 22. The details of the roller fixing device 22 are explained in the second section.
As shown in the figure. The heating roller 24 of the roller fixing device 22 is a metal pipe 25 whose surface is coated with a silicone rubber layer 26, and the pressure roller 27 is a metal pipe 28 whose surface is coated with a Teflon layer 29. A lamp 30 is provided.

The rollers 24 and 27 constitute a pair of fixing rollers.
A roller 31 is further pressed against the fixing roller 24.
This roller 31 is made of a metal pipe 32, and an infrared lamp 33 is disposed inside it. The silicone oil 35 in the container 34 is pumped up by the application felt 36 and applied to the surface of the roller 31, and then applied to the surface of the roller 31.
One surface of silicone oil is applied to the surface of the heating roller 24. The coating felt 36 is supported by a rotating shaft 38 together with a presser plate 37, and is moved by an electromagnetic plunger 39 and a tension spring 40 between a coating position in which it contacts the roller 31 and a non-coating position in which it does not contact. The transfer paper 15 having the toner image is sent between a pair of fixing rollers 24 and 27 to be fixed thereon, and then discharged onto a tray 23. FIG. 3 shows a block diagram of the silicone oil application amount control circuit.

The yellow, magenta, cyan, and black ATR leg circuits 50 are provided with illumination lamps 511, 512, and 513, respectively.
, 514, CdS receiver 52, , 522, 523, 52
4. Analog-digital (A-D) conversion circuit 531, 5
32, 533, 534 and a toner replenishment control device 54, 542 having a clutch for opening and closing the hopper replenishment valve.
, 543, 544, but each A
A part of the output signal voltage of the -D conversion circuit is extracted and guided to the arithmetic circuit 55.

Monochrome, two-color, or three-color development is performed in the developing unit 14, and each toner replenishment signal (toner density signal)
When this occurs, the signal voltage is integrated in the calculation circuit 55, and when all the development for one copy is completed and the transfer paper is separated from the gripper by the separation claw, the integrated signal voltage is used to control the silicone oil application. It is sent to the circuit 56, and the electromagnetic plunger 39 of the roller fixing device 22 is energized according to the sum of the toner replenishment time, and the application felt 36 comes into contact with the roller 31 to apply silicone oil.

Here, a constant DC voltage may be applied to the output side of the arithmetic circuit so that the application felt operates for a certain period of time even when toner is not replenished at all.

When the signal from the arithmetic circuit 55 is sent to the next stage, the arithmetic circuit is reset. FIG. 4 shows another embodiment of the present invention.

However, FIG. 4 only shows the vicinity of the color separation filter group 8 in the copying machine of FIG. 1. In FIG. 4, the receiver 6
0 consists of a condensing lens 61 and a CdS light receiving element 62, and is located behind a half mirror 9' that replaced mirror 9 in FIG. A portion of the light that has passed through the color separation filter group 8 passes through a half mirror 97 and is guided to the light receiver 60, where the original density is detected. A silicone oil application amount control circuit in the embodiment shown in FIG. 4 is shown in FIG.

The original density signal voltage obtained by the light receiver 60 and the A/D conversion circuit 63 is inverted by an arithmetic circuit 64 so that it becomes larger when the density of the original is high. The output is integrated in an arithmetic circuit 65. The signal voltage integrated for each color separation exposure for one copy is sent to the silicone oil replenishment control circuit 66 at the next stage when the transfer paper is separated from the gripper 1 by the separation claw, and the signal voltage is sent to the next stage silicone oil replenishment control circuit 66 to determine the original reflection density at each color separation exposure. The electromagnetic plunger 39 of the roller fixing device 22 is energized in accordance with the sum of , and the application felt 36 contacts the roller 31 to apply silicone oil.

When the signal from the arithmetic circuit 65 is sent to the next stage, the arithmetic circuit 6
5 is set. The method of controlling the amount of silicone oil applied according to the present invention is not limited to the method of controlling the contact time of the coated felt with the roller of this embodiment, but can also be applied to controlling the amount of applied silicone oil in known oil application methods such as application with a roller and application with a spray. Applicable. The present invention focuses on the amount of toner adhering to a transfer paper or copying material as a member to be fixed, and determines the amount of anti-offset liquid applied based on a detection signal that is correlated with the amount of toner adhering when the amount of toner adhering to the member to be fixed is large. Since it is controlled so that the amount of toner does not increase, it prevents offsets from occurring frequently due to the amount of toner adhering, and enables stable fusing.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a color copying machine to which the present invention is applied;
Fig. 2 is a configuration diagram showing the fixing device of the copying machine, Fig. 3 is a circuit diagram for controlling the amount of silicone oil applied, Fig. 4 is a diagram showing another embodiment of the detection means, and Fig. 5 is a diagram showing the silicone oil application amount control circuit. Diagram showing another embodiment of the leg circuit 22...Roller fixing device, 24...Heating roller, 27...
...pressure roller, 35... silicone oil,
36...Coating felt, 39...Electromagnetic plunger.

Claims (1)

[Scope of Claims] 1. A fixing device having a fixing roller for fixing a toner image on a member to be fixed, and means for applying an anti-offset liquid to the fixing roller; The method further includes means for controlling the amount of offset prevention liquid applied to the fixing roller by the offset prevention liquid applying means in accordance with a correlated detection signal so that the amount of the offset prevention liquid applied to the fixing roller increases when the amount of toner adhering to the fixing member is large. This is a unique fixing device. 2. In claim 1, the fixing device is provided in an electrophotographic apparatus, and the detection signal is a toner concentration signal from means for detecting developer concentration in a developing section of the electrophotographic apparatus. fixing device. 3. The fixing device according to claim 1, wherein the fixing device is provided in an electrophotographic apparatus, and the detection signal is an original image density signal from means for detecting document density of the electrophotographic apparatus. 4. In claim 1, the fixing device is provided in an electrophotographic apparatus, and the detection signal is a developed image from a means for detecting the density of the developed image on a photoreceptor or a member to be fixed of the electrophotographic apparatus. A fixing device characterized by a density signal. 5. In claim 1, the fixing device is provided in an electrophotographic apparatus, and the detection signal is a latent image potential signal from a means for detecting a latent image potential of a photoreceptor of the electrophotographic apparatus. Fixing device.