JPH04242276A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate troublesome gap adjusting work between a toner image carrier and a pressure transfer body and to surely relax an impact when a transfer material is rushed between the toner image carrier and the pressure transfer body, or the material is released from therebetween, without having influence by the thickness of the transfer material. CONSTITUTION:In the image forming device having the toner image carrier 1 on which a toner image is carried, and the pressure transfer body 3 which is disposed to be adjoined to the toner image carrier 1, and pressuretransfers or pressure-transfers/fixes the toner image on the toner image carrier 1 to the transfer material 2 in such a manner that the inserted transfer material 2 is press-contacted to the side of the toner image carrier 1, a transfer material thickness detecting means 4 detecting the thickness of the transfer material 2, and a gap adjusting means 5 automatically changing a gap delta between the above-mentioned toner image carrier 1 and the pressure transfer body 3 according to detection information from the transfer material thickness detecting means 4.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to image forming apparatuses such as copying machines and printers, and particularly to image forming apparatuses such as copying machines and printers, and particularly to an image forming apparatus in which a toner image carried on a toner image carrier is pressure-transferred or pressure-transferred and fixed onto a transfer material. This invention relates to improvements in image forming apparatuses.

0002

2. Description of the Related Art Conventionally, as an image forming apparatus of this type, a technique disclosed in, for example, Japanese Patent Laid-Open No. 61-90167 is already known.

[0003] This includes a toner image carrying drum on which a toner image is carried, and a pressure roll that is placed adjacent to this toner image carrying drum and presses a recording sheet inserted therebetween. The toner image carried on the toner image carrying drum is pressure-transferred or pressure-transferred and fixed onto the recording sheet.

By the way, in this type, if the toner image bearing drum and the pressure roll are always placed in pressure contact with each other, when the recording sheet enters between them or when the recording sheet leaves from between them, A large impact is generated on the toner image bearing drum, which tends to cause rotational fluctuations in the toner image bearing drum, resulting in a technical problem in that the latent image is disturbed when it is formed on the toner image bearing drum.

[0005] In order to solve such technical problems,
In the prior art, a gap corresponding to the thickness of the recording sheet is provided between the toner image bearing drum and the pressure roll to reduce the impact when the recording sheet enters or leaves the recording sheet.

[0006]

[Problems to be Solved by the Invention] However, in this type, the gap between the toner image bearing drum and the pressure roll is uniquely set in accordance with the thickness of a predetermined recording sheet. For example, when recording sheets with different thicknesses are used, it is necessary to manually readjust the gap between the toner image-bearing drum and the pressure roll. This poses a technical problem in that gap adjustment becomes extremely troublesome for users who frequently use different recording sheets.

[0007] Based on the same concept as the prior art described above, for example, as shown in FIG. An elastic body 52 made of a material with low hardness is provided, and at the timing of entering and leaving the recording sheet 53,
The elastic body 5 is provided at a portion facing the toner image bearing drum 50.
Adjust so that 3 is placed, enter the recording sheet 53,
As shown in FIG. 7, the outer diameter of the pressure roll 51 is configured in two stages to reduce the impact when the recording sheet 53 enters and leaves the toner image bearing drum 50. It is conceivable that the transition area from the large diameter part 51a to the small diameter part 51b of the pressure roll 51 is arranged in a region facing the pressure roll 51, so as to reduce the impact caused when the recording sheet 53 enters and leaves the recording sheet 53. but,
In any case, the hardness of the elastic body, the large diameter portion 51a and the small diameter portion 5
1b is uniquely set according to the thickness of a predetermined recording sheet, and not only is it impossible to respond immediately to recording sheets 53 of different thicknesses, but also the gap between the pressure roll 53 and the It is necessary to set the length of the pressure roll 53 to be at least the length of the recording sheet 53, and a situation arises in which the pressure roll 53 becomes larger accordingly.

The present invention has been made to solve the above technical problems, and eliminates the need for troublesome gap adjustment work, and allows the toner image bearing member to be processed without being affected by the thickness of the transfer material. An object of the present invention is to provide an image forming apparatus that can reliably reduce the impact when a transfer material enters between the pressure transfer member and the transfer material and when the transfer material leaves the space between the two.

[0009]

[Means for Solving the Problems] That is, as shown in FIG. 1, an image forming apparatus according to the present invention includes a toner image carrier 1 on which a toner image is carried, and a toner image carrier 1 disposed adjacent to the toner image carrier 1. , the inserted transfer material 2 is pressed against the toner image carrier 1 side, and the toner image on the toner image carrier 1 is transferred to the transfer material 2.
It is assumed that the image forming apparatus is equipped with a pressure transfer member 3 that performs pressure transfer or pressure transfer fixing to a transfer material 2, and a transfer material thickness detection means 4 that detects the thickness of the transfer material 2, and a transfer material thickness detection means 4 that detects the thickness of the transfer material 2. The toner image carrier 1 is linked to the detected information.
The present invention is characterized in that it includes a gap adjusting means 5 for automatically changing the gap δ between the transfer member 3 and the pressurized transfer member 3.

[0010] In such technical means, the toner image carrier 1 may be any material that can form an electrostatic latent image that is visualized with toner and can also carry a toner image. , it may be formed of a dielectric or a photoreceptor, and it does not matter whether it is drum-shaped or belt-shaped.

Further, as the transfer material thickness detecting means 4, any known sensor such as a mechanical type or an optical type can be used as long as it can detect the thickness of the transfer material 2. In this case, as the detection information of the transfer material thickness detection means 4, the thickness information of the transfer material 2 may be output as is, or the thickness information of the transfer material 2 may be converted into level information divided into at least a plurality of stages. It is also possible to output it as follows.

Further, the gap adjusting means 5 moves at least one of the pressure transfer member 3 and the toner image bearing member 1 in conjunction with the detection information from the transfer material thickness detecting means 4 to maintain a predetermined distance between the two. As long as the gap δ is set, the design may be changed as appropriate. In this case, the gap δ may be appropriately selected as long as it can reduce the impact when the transfer material 2 enters or leaves the transfer material 2 without causing any hindrance to the pressurizing operation of the transfer material 2. , 30% to 90%, preferably 50% to 80% of the thickness of the transfer material 2.

[0013]

[Operation] According to the technical means described above, the transfer material 2
When the transfer material thickness detection means 4 passes through the transfer material thickness detection means 4, the transfer material thickness detection means 4 detects the thickness of the transfer material 2, and this detection information is sent to the gap adjustment means 5. Then, the gap adjusting means 5 automatically adjusts the gap δ between the toner image bearing member 1 and the pressure transfer member 3 in conjunction with the above detection information, and
Reduces the impact when the vehicle enters or leaves the vehicle.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on embodiments shown in the accompanying drawings. FIG. 2 shows an electrostatic recording device to which the present invention is applied. In the same figure, the reference numeral 10 is a dielectric drum having a dielectric layer formed on its surface, and in this example, the surface of an aluminum pipe was subjected to an anodizing coating treatment (coating thickness of about 30 to 60 μm) and then sealing treatment. things are used. Further, 11 is a charging corotron that charges the surface of the dielectric drum 10 in advance; 12 is an ion current writing head for writing an electrostatic latent image on the dielectric drum 10;
3 is a developing device that visualizes the electrostatic latent image on the dielectric drum 10 with toner, and 14 is a pressure roll that is arranged adjacent to the dielectric drum 10 and transfers and fixes the inserted recording sheet 15 under pressure. For example, the iron core is made of organic resin (3 to 20 m thick).
(approximately 100 m) is used. Furthermore, 16 is a cleaner for removing residual toner on the dielectric drum 10;
7 is an eraser for removing residual charges on the dielectric drum 10, and 18 is a thickness sensor for detecting the thickness of the recording sheet 15.

In this embodiment, the thickness sensor 18
As shown in FIG. 3, the fixed position roll 21 is rotatably supported at a predetermined position, and the fixed position roll 21 is biased toward the fixed position roll 21 by a spring member not shown and is freely displaceable with respect to the fixed position roll 21. displacement roll 22 and this displacement roll 22
The limit switch 24 has a contact 24a turned on when the bending deformation of the plate spring 23 exceeds a predetermined amount.

Further, the pressure roll 14 is supported at an intermediate portion of a swinging arm 31 with one end as the swinging center.
The swinging arm 31 is biased toward the dielectric drum 10 by a spring member 32, while an eccentric cam 33 at the free swinging end of the swinging arm 31 resists the biasing direction of the spring member 32. The eccentric cams 33 are arranged in contact with each other, and the eccentric cams 33 are rotated by a drive motor 34.

Further, a signal from the limit switch 24 (thickness detection signal of the recording sheet 15) is sent to a motor drive circuit 35, which drives the drive motor 34 to rotate as appropriate. The swinging arm 31 is appropriately swung via the oscillating arm 31 to variably adjust the gap between the dielectric drum 10 and the pressure roll 14 in accordance with the thickness of the recording sheet 15.

Next, the operation of the electrostatic recording apparatus according to this embodiment will be explained. Now, assuming that the thickness of the recording sheet 15 is thin, as shown in FIG.
Even if it passes through the thickness sensor 18 portion, the amount of displacement of the displacement roll 22 is small, so the leaf spring 23 will not turn on the contact 24a of the limit switch 24. At this time, the eccentric cam 33 is arranged at the position shown by the solid line in FIG.
The thickness is set to be narrower than the thickness d1 of No. 5.

Further, assuming that the recording sheet 15 is thick, as shown in FIG. The contact 24a of the limit switch 24 is turned on. Then, the motor drive circuit 34 moves the eccentric cam 33 by 180 degrees from the position shown by the solid line in FIG.
The eccentric cam 33 is placed at the position shown by the imaginary line in FIG. Gap g2 is set wider than g1. At this time, the gap g2 between the dielectric drum 10 and the pressure roll 14 is the thickness d of the recording sheet 15, as shown in FIG.
It is set to be narrower than 2.

In this operation process, the pressure load applied to the A4 size recording sheet 15 is 300 to 1,000 kg.
The gap between the dielectric drum 10 and the pressure roll 14 is changed while maintaining the recording sheet 15 within the range of g.
When the amount of speed variation (peak to peak) of the dielectric drum 10 when it enters was measured, the results shown in FIG. 5 were obtained.

According to FIG. 5, the larger the gap between the dielectric drum 10 and the pressure roll 14, the smaller the amount of speed fluctuation of the dielectric drum 10 when the recording sheet 15 enters. However, if the gap becomes extremely large, the pressurizing load on the recording sheet 15 becomes insufficient, so this embodiment was designed in consideration of detection errors in the thickness of the recording sheet 15, gap setting errors, etc. , the gaps g1 and g2 are each recording sheet 1.
The thickness of the recording sheet 1 is selected to be approximately 50 to 80% of the thickness of the recording sheet 1.
The amount of speed fluctuation of the dielectric drum 10 when 5 enters is 5%.
At the same time, a sufficient pressure load on the recording sheet 15 was ensured.

[0022]

As described above, according to the invention as claimed in claim 1 or 2, the gap between the toner image bearing member and the pressure transfer member is automatically adjusted according to the thickness of the transfer material. This eliminates the need for troublesome gap adjustment work, and eliminates the need for troublesome gap adjustment work, and eliminates the need for transfer when the transfer material enters between the toner image bearing member and the pressure transfer member, or between the two, without being affected by the thickness of the transfer material. It is possible to reliably reduce the impact when the material is separated.

In particular, according to the invention as claimed in claim 2, when the transfer material enters between the toner image bearing member and the pressure transfer member, or both, within a range that does not impede the pressing operation of the transfer material. It is possible to reliably reduce the impact when the transfer material is separated from the gap.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an outline of an image forming apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing an embodiment of the electrostatic recording device to which the present invention is applied.

FIG. 3 is an explanatory diagram showing a specific example of the thickness sensor and gap adjustment means according to the embodiment.

FIG. 4 is an explanatory diagram showing a gap adjustment process of the gap adjustment means according to the embodiment.

FIG. 5 is a graph diagram showing the relationship between the gap of the gap adjusting means and the speed fluctuation amount of the dielectric drum according to the embodiment.

FIG. 6 is an explanatory diagram showing an example of a conventional image forming apparatus.

FIG. 7 is an explanatory diagram showing another example of a conventional image forming apparatus.

[Explanation of symbols]

1 Toner image carrier 2 Transfer material 3 Pressure transfer body 4 Transfer material thickness detection means 5 Gap adjustment means

Claims (2)

[Claims] 1. A toner image carrier (1) on which a toner image is carried, a toner image carrier (1) disposed adjacent to the toner image carrier (1),
The inserted transfer material (2) is pressed against the toner image carrier (1) and transfers the toner image on the toner image carrier (1) to the transfer material (
2) Pressure transfer body (pressure transfer or pressure transfer fixation)
3), the image forming apparatus includes the transfer material (2);
) for detecting the thickness of the toner image carrier (1) and the pressure transfer member (3) in conjunction with the detection information from the transfer material thickness detection means (4). gap adjustment means () that automatically changes the gap (δ) between
5) An image forming apparatus comprising: 2. In the apparatus according to claim 1, the gap adjustment means (5) adjusts the gap (δ) between the toner image bearing member (1) and the pressure transfer member (3) to the transfer material (2). An image forming apparatus characterized in that the thickness is set to about 50 to 80% of the thickness of the image forming apparatus.