JPH0486779A - Image forming device - Google Patents

Abstract

PURPOSE:To always obtain an image with excellent quality by providing a supporting means which fixes the position of an image carrier with respect to a transfer roller to be constant when the image carrier press-contacts with the transfer roller. CONSTITUTION:The transfer roller 15 is supported by blocks 12a and 12b provided at both end parts of a supporting member 13 which is mounted on a main body side. In the case that an upper cover is closed, shafts parts on both surfaces of the image carrier 5 are engaged with recessed parts provided on the tops of the blocks 12a and 12b. Then, the transfer roller 15 on the main body side press-contacts with it and a transfer part is formed. An arm 21 is arranged to a pin 22 disposed on the block 12b so as to be freely turned and slided and the shaft end 19 of the transfer roller 15 is turnably supported by the bearing part 20 of the arm 21. Besides, a spring abuts on the end part of the arm 21 on a side which is opposite to the pin 22 and the transfer roller 15 is biased in the direction of the image carrier 5 by it. Thus, relative positional relation between both of them is stably and precisely maintained and the image with excellent quality is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention ((Industrial Application Field) The present invention relates to an image forming apparatus using an electrostatic transfer process, such as an electrostatic copying machine and a printer thereof.

(Prior Art and Problems to be Solved) In the image forming apparatus as described above, the housing is divided into upper and lower halves, the upper cover is configured to be openable and closable with respect to the lower main body, and multiple parts including the image carrier are On the other hand, devices in which the image forming member is usually placed on the upper cover side have already been widely used.

FIG. 8 is a partially cutaway side view showing a typical example of an image forming apparatus having such a structure, and the figure shows a state in which the upper cover is opened.

A cartridge 16 containing a rotating cylindrical image carrier 5 is disposed on the top cover, and when the top cover is closed and printing is possible, the image carrier 5 is attached to a transfer plate located on the main body side. It is configured to come into contact with the roller 15.

By the way, in an apparatus in which a transfer site is constituted by an image carrier and a transfer roller that is in pressure contact with the image carrier, and a transfer material is inserted into the site, it is necessary to maintain the pressure contact between the two with high precision. Usually, such devices do not take special measures to compensate for this, and as a result, the transfer material is not conveyed accurately in a direction perpendicular to the axis of the image carrier, resulting in distorted images or damage to the transfer material. Problems such as wrinkles could not be avoided.

The present invention has been made to cope with such a situation, and provides an image forming apparatus that includes an image bearing member and a transfer roller that is in pressure contact with the image bearing member, and that can separate the two as necessary. It is an object of the present invention to provide an image forming apparatus that can consistently maintain a relative positional relationship between the two and obtain high-quality images at all times.

(2) Structure of the invention (technical means for solving the problem and its operation) In order to achieve the above object, the present invention includes a rotating cylindrical image bearing member and a transfer roller that is in pressure contact with the image bearing member. In an image forming apparatus that is configured so that the two can be brought into contact with and separated from each other, and that performs transfer by inserting a transfer material between the two that are in pressure contact with each other, there is provided a support means that keeps the position of the image carrier relative to the transfer roller constant when the two are in pressure contact with each other. It is characterized by the following:

With this configuration, even in an apparatus where the image bearing member and the transfer roller may be separated from each other, the positional relationship between the two can always be maintained in a predetermined manner, and stable transfer performance can always be obtained. can.

(Description of Embodiments) FIG. 1 is a schematic side view showing the internal structure of an image forming apparatus showing an embodiment of the present invention, and basically similar to the apparatus shown in FIG. It has an openable and closable upper cover that houses a cartridge 16 including a carrier 5, and the figure shows the state in which printing is possible with the upper cover closed.

The transfer material S taken out from the cassette 2 passes through a pair of registration rollers 4 and is fed to the transfer site in synchronization with the toner image formed on the surface of the image carrier 5 up to this point.

After the transfer, the transfer material carrying the toner image passes through a fixing section 6, where the toner image is fixed and fixed to the transfer material, and in the case of one-sided printing, is advanced upward by a flapper 8, and is moved upward by a discharge roller 7.
is discharged onto the tray T.

In the case of double-sided printing, the transfer material whose first side has been fixed is guided downward by the flapper 8, and transferred to the double-sided conveyance section 9.
The transfer material is conveyed in a reverse direction by a reversing roller 10 that can be forward-reversed, and is conveyed to a pair of registration rollers 4 via a pair of re-feeding rollers 11, and thereafter image forming operations are performed in the same manner as in the case of the first side.

In such an apparatus, as in the case shown in FIG. 8, the image carrier 5 is disposed in the process cartridge 16 inside the upper cover which can be opened and closed, and the transfer roller 15 is disposed on the side of the image carrier. , when the top cover is opened,
Image carrier 5 and transfer roller 15 are separated.

As shown in the figure, the transfer roller 15 is supported by blocks 12a and 12b provided at both ends of a support member 13 placed on the main body side and extending in a direction perpendicular to the plane of the paper.

FIG. 2 shows an image carrier 5 and a transfer roller 15 that is in pressure contact with the image carrier 5.
This is a perspective view showing only the support relationship between the
Blocks 12a, 1 provided at both ends of the support member 13
The shaft portions at both ends of the image carrier are engaged with the recesses a provided at the top of the image carrier 2b, and the transfer roller 15 on the main body side is pressed against the recesses a to form a transfer region.

FIG. 3 is a perspective view showing the support structure of the transfer roller 15, and this figure shows only the block 12b side, and it is assumed that the other block 12a side has a similar structure.

An arm 21 is rotatably and slidably disposed on a bin 22 disposed on the inner surface of the block 12b, and a shaft end 19 of the transfer roller 15 is rotatably supported by a bearing portion 20 of the arm 21. There is.

Furthermore, the other end of a spring 23 whose one end is supported by a protrusion 12c formed on the support member 12 is in contact with the end of the arm 21 opposite to the bottle 22. The transfer roller 15 is biased upward in the drawing, that is, in the direction of the image carrier 5 (not shown).

As mentioned above, the arm 21 can slide on the bin 22, so by displacing the arm 21 from the solid line position to the dotted line position as shown in FIG. It is possible to pull out the shaft end 19 from the bearing part 20 of the arm 21 and remove it.

As described above, with the illustrated configuration, in an image forming apparatus using an image carrier and a transfer roller, the relative positions of the two can be stably and accurately maintained during use, and the transfer roller, which is prone to wear, can be maintained and maintained. Even if they are replaced, their positional relationship will not be disrupted, and good transfer performance can always be ensured.

FIG. 5 shows another embodiment of the present invention, in which only the portions that support the image carrier and the transfer roller are shown.

In this device, rising portions 13a and 13b are formed at both ends of a support member 13 fixed to the main body of the image forming apparatus, and when the apparatus is placed in a printing-enabled state, in the recessed portion a formed at the top of these rising portions, The shaft end of the image carrier 5 is configured to be engaged and supported.

It will be easily understood that with this configuration, the relative position between the image carrier and the transfer roller can be stably maintained in a predetermined manner, as in the case described above.

6 and 7 show still another embodiment of the present invention, FIG. 6 is a perspective view showing its configuration, and FIG. 7 shows the image carrier and transfer roller when printing is possible. FIG. 3 is an end view showing the related arrangement.

Cartridge 16 disposed on the top cover of the image forming apparatus
Positioning engaging members 24a and 24b having openings 24a' and 24b' provided below are attached to portions corresponding to both axial ends of the image carrier 5.

On the other hand, on the main body side, although not shown, arms 25a and 25b are disposed on a member having the same effect as the block or rising portion in each of the above embodiments, and are biased upward in the figure by a spring 23. The shaft end of the image carrier 5 is slidably attached to a long hole 25a25b formed in each arm.

With this configuration, when the top cover is closed to enable printing, the engaging member 24a on the cartridge side,
Openings 24a° and 24b' of 24b engage with the axial ends of the image carrier 5, respectively, and the elongated holes 25a' and 25b
'The transfer roller 15 is appropriately displaced by the action of the image carrier 5.
This means that the relative position between the transfer roller 15 and the transfer roller 15 can be maintained constant at all times.

In such a configuration, by appropriately setting the shapes of the engaging members 24a and 24b, it is effective to prevent damage to the image carrier of the cartridge that is attached to and removed from the upper cover.

The present invention has been described above with reference to an embodiment in which the present invention is applied to a cartridge type image forming apparatus, but the present invention is not limited to this. It will be easily understood that the invention can also be applied to other image forming apparatuses configured so that these two parts can be separated from each other.

(3) As described in detail, the present invention provides an image forming apparatus that is provided with an image carrier and a transfer roller that is in pressure contact with the image carrier, and that is configured to move the two toward and away from each other as necessary. The relative positional relationship between the two can be maintained stably and accurately at all times without impairing the operability or serviceability of the device, resulting in good transfer performance and a remarkable effect on obtaining high-quality images.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of an image forming apparatus showing an embodiment of the present invention, FIG. 2 is a perspective view showing the structure of the image bearing member and the transfer roller vicinity, and FIGS. 3 and 4 are the same as above, respectively. FIG. 5 is a partial perspective view and end view showing how the transfer roller is mounted; FIG. 5 is a perspective view showing another embodiment of the configuration of the image carrier and the vicinity of the transfer roller; FIGS. 6 and 7 are: FIG. 8 is a partially cutaway schematic side view showing the configuration of a known image forming apparatus. 2...Cassette, 4...Register roller, 5...
Image carrier, 12a, 12b...block, 13...
Support member, 15...Transfer roller, 16...Cartridge, 21...Arm, 22...Bin, 23...Spring, 24a, 24b...Engagement member, 25a, 25b.
··arm. ■ Figure 1 Figure 3 (+2b) Figure 2 Figure 4

Claims (3)

[Claims] (1) It is equipped with a rotating cylindrical image carrier and a transfer roller that is in pressure contact with the image carrier, and is configured so that the two can be moved toward and away from each other as necessary, and a transfer material is inserted between the two that are in pressure contact to perform transfer. An image forming apparatus comprising a support means for fixing the position of an image bearing member with respect to a transfer roller when the two are in pressure contact with each other. (2) The image forming apparatus according to claim 1, further comprising means for independently attaching and detaching the transfer roller from the support means. (3) The image forming apparatus according to claim 1, wherein the supporting means comprises means for displacing the transfer roller with respect to the image carrier fixed in a fixed position.