JPH0416884A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate limitations of the arrangement of a transfer roller and to reduce the size of the device by setting a position, which faces the pressure transfer roller across a photosensitive drum, between two fixed support rollers among plural support rollers. CONSTITUTION:The photosensitive drum 12 is supported inside at three points by the fixed support rollers 15 and 16 and a movable support roller 17; and those support rollers 15 - 17 are arranged both width-directional ends of the photosensitive drum 12. The movable support roller 17 is arranged on the line connecting the centers of the driving roller 13 and photosensitive drum 12. Namely, the movable support roller 17 is provided at the position facing the driving roller 13 across the photosensitive drum 12. Further, the fixed support roller 15 is arranged on the prolongation of the exposure position of the photo sensitive drum 12, the fitting shafts of the fixed support rollers 15 and 16 are fixed directly to side plates 18 arranged at both ends of the photosensitive drum 12, and the fitting shaft 19 of the movable support roller 17 is not fixed directly to the side plate 18. Consequently, the device is reduced in size.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image forming apparatus, and in particular, for example, an exposure light source is disposed inside a photoreceptor drum, and an exposure light source is provided inside the photoreceptor drum to expose the image from the inside of the photoreceptor drum at the same time or immediately after. The present invention relates to an image forming apparatus that develops toner.

[Prior Art] Conventionally, in this type of image forming apparatus, a pressure transfer roller has been disposed at a position facing a roller that supports a photoreceptor drum.

[Problems to be Solved by the Invention] In the conventional method described above, there are restrictions on the arrangement of the support rollers that support the photosensitive drums. For example, in the case of 3-point support,
They must be placed at or near 120° intervals. Therefore, there are restrictions on the arrangement of the transfer rollers, and therefore the conveyance path is restricted.

The present invention was made to solve the above problems, and an object of the present invention is to provide an image forming apparatus in which a photosensitive drum is not affected by pressure.

[Means to solve the problem]

The image forming apparatus according to the present invention is provided with a plurality of support rollers that rotatably support the photoreceptor drum from inside, and among these rollers, the inner surface facing the pressure transfer roller is
between two fixed support rollers.

[Function 1] In this invention, there is a degree of freedom in the arrangement of the pressure transfer roller, and the degree of freedom in the conveyance path is also increased. Furthermore, even if the pressure of the pressure transfer roller is applied to the photosensitive drum, the photosensitive drum is not affected by the pressure because it is between two fixed support rollers.

[Example 1 Fig. 1 is a sectional view showing an optical printer as an embodiment of the present invention, and Fig. 2 is a partially cutaway view of the latent image carrier unit of the embodiment of Fig. 1. The perspective view and Figure 3 are the same (
The cross-sectional view and FIG. 4 are the same (partially enlarged cross-sectional view of the photoreceptor drum).The present invention will be described below as being applied to an optical printer, but the present invention can also be applied to other image forming apparatuses,
For example, it can be applied to copying machines, facsimile machines, etc.

In FIG. 1, an optical printer 10 includes a main body 11, and a photosensitive drum 12 is rotatably supported inside the main body 11. As shown in FIG. 4 (see JP-A-58-153957), the photosensitive drum 12 includes a transparent base 12a made of, for example, glass, and a transparent conductive layer 12b laminated on the transparent base 12a. and photoconductor layer 12c
including.

Outer surface of photoconductor drum 12 (surface of photoconductor layer 12c)
A drive roller 13 is provided so as to be in contact with the photoreceptor drum 12 , and the drive roller 13 rotates the photosensitive drum 12 by a driving force from a drive source of a motor 14 . The photosensitive drum 12 is rotatably supported by two fixed support rollers 15 and 16 that are in contact with its inner surface, that is, the surface of the transparent substrate 12a, and one movable support roller 17 (see FIG. 3). , when the drive roller 13 rotates in the direction of arrow A, the photosensitive drum 12 also rotates in the direction of arrow B accordingly. As shown in FIG. 2, the drive rollers 13 are arranged at both ends of the photoreceptor drum 12 in the axial direction;
The surface of the end of the photosensitive drum 12 that comes into contact with the drive roller 13 is formed somewhat rough, so that the photosensitive drum 12 is accurately rotated by friction between the two.

As mentioned above, the photoreceptor drum 12 has fixed support rollers 15 and 16 and movable support roller 1 on its inside.
7, it is supported by 3 points. Each of these support rollers 15
17 are arranged at both ends of the photoreceptor drum 12 in the width direction. The movable support roller 17 is the driving roller 13.
and the center of the photoreceptor drum 12. That is, the movable support roller 17 is provided at a position facing the drive roller 13 with the photoreceptor drum 12 in between. Also,
The fixed support roller 15 is arranged on an extension line of the exposure position of the photoreceptor drum 12.

The mounting shafts of the fixed support rollers 15 and 16 are directly fixed to side plates 18 disposed at both ends of the photosensitive drum 12, respectively. On the other hand, the mounting shaft 19 of the movable support roller 17
is not directly fixed to the side plate 18. That is, the mounting shaft 19 of the movable support roller 17 is attached to the side plates 18 on both sides by the coil spring 2o so that the movable support roller 17 can apply a pressing force from the inside to the outside of the photosensitive drum 12. Therefore, the movable support roller 17
follows the radial variation of the inner periphery of the photoreceptor drum 12, and can be brought into close contact with the photoreceptor drum 12 under constant pressing force. Therefore, fixed support rollers 15 and 16
The contact position of the movable support roller 17 on the inner periphery of the photoreceptor drum 12 remains constant even if the inner periphery of the photoreceptor drum 12 is eccentric, but the contact position of the movable support roller 17 changes depending on the eccentricity of the inner periphery of the photoreceptor drum 12. Follow and change. Therefore, even if the diameter or roundness of the photosensitive drum 12 varies, for example, such dimensional variations can be absorbed by the displacement of the movable support roller 17.

The mounting shaft 19 of the movable support roller 17 has a length that passes through both ends of the photoreceptor drum 12 in the axial direction, while the mounting shafts of the fixed support rollers 15 and 16 are individually mounted to the side plates 18 at both ends. Note that a gap is formed between the fixed support rollers 15 for exposing the photosensitive drum 12.

Inside the photosensitive drum 12, an LED head 21 is further provided.
is placed. An LED array 21a is formed on one main surface of the LED head 21, in which a large number of LED elements are arranged in a straight line extending in the width direction of the photoreceptor drum 12.
The light from this LED array 21a is transmitted to a rod lens array fixed to the LED head 21 by an arm 22a.
That is, the focusing light transmitter 22 transmits the photoconductor layer 12 between the fixed support rollers 15 on both sides through the transparent base 12a and the transparent conductive layer 12b of the photoconductor drum 12.
irradiated to c.

By arranging the fixed support roller 15 on the optical axis of the exposure light in this manner, the exposure light can be reliably focused on the photoconductor layer 12c of the photoreceptor drum 12. That is, at the position where the exposure light is irradiated, the photoreceptor drum 12 is always maintained at a constant position by the fixed support roller 15, so that the position of the photoconductor layer 12c where the exposure light is irradiated does not change.

As shown in FIGS. 2 and 3, the photosensitive drum 12.
The LED head 21 and the like are fixed to a pre-formed support member 23 with a mounting shaft.

A developing device 24 is provided on the right side of the photosensitive drum 12.

The developing device 24 is rotated upward about the support shaft 23a, and is attached so as to be always pulled toward the photosensitive drum 12 by a coil spring (not shown). The developing device 24 includes a magnet roller 25. A panicle control plate 26 and the like are provided.

The toner is formed as a magnetic brush on the circumference of the magnet roller 25, and the height of the magnetic brush, that is, the height of the spikes, is adjusted by the spike regulating plate 26, and the toner is applied to the photosensitive drum according to the rotation of the magnet roller 25. Transferred to the part facing 12. That is, the toner is transferred to the magnetic roller 25.
and the photoconductor layer 12c of the photoreceptor drum 12.

In order to perform good toner development, it is not only necessary to accurately set the gap between the portion where the magnet roller 25 and the photoreceptor drum 12 face each other, but also to ensure that the gap is aligned with the optical axis of the exposure light. The magnet roller 25 and the photoreceptor drum 12 need to be positioned so that they are exactly perpendicular to each other.

Therefore, in this embodiment, the above-mentioned positioning of this part is performed by the second. As shown in FIG. 3, a developing device 24 is fixed to a support member 23 of the photosensitive drum 12. On the other hand,
The above-mentioned interval is determined by rotatably providing gap rollers 27 at both ends of the magnet roller 25 and bringing the gap rollers 27 into contact with the surface of the photoreceptor drum 120.

However, simply fixing each to the support member 23 as described above does not necessarily mean that the portion facing the magnet roller 25 is accurately orthogonal to the optical axis of the exposure light. In that case, by simply slightly rotating the side plate 18 that fixes the LED head 21, the LED head 21 provided within the photoreceptor drum 12, that is, the focusing light transmitting body 2
2 positions can be easily adjusted.

The latent image carrier unit configured in this manner can be attached to and detached from the main body 11 in this state.

Next, the operation will be explained.

Magnet roller 25 of developing device 24 and photosensitive drum 1
A voltage is applied between the transparent conductive layer 12b of No. 2 and the LED head 21 and the focusing light transmitter 22 arranged on the inner surface of the photoreceptor drum 12 to irradiate image information to the corresponding photoreceptor drum. A toner image is formed on the surface of 12.

On the other hand, the recording paper 29 fed by the paper feed roller 28 is
After timing is determined by the register roller pair 30, the recording roller pair 30 conveys the recording material to the transfer position.

Next, the recording paper 29 is pressed between the photosensitive drum 12 and the pressure transfer roller 31, and the toner image is transferred onto the recording paper 29. The pressure transfer roller 31 is supported so as to be rotatable around a support shaft 32, and the transfer position is between the fixed support rollers 15 and 16 of the photoreceptor drum 12 via the photoreceptor drum 12. become. The recording paper 29 on which the toner image has been transferred is separated from the photoreceptor drum 12 by a separating claw 33, and is sent by a pressure transfer roller 31 and a photoreceptor drum 12, and then further transferred to a heating roller 34 and a pressure roller 35.
The image is transported to a fixing device consisting of

In the fixing device, the storage paper 29 to which the toner image has been transferred is heated and pressurized to fix the toner image, separated by a separating claw 36, and discharged to the outside of the main body 11.

〔Effect of the invention〕

As described in detail above, in this invention, the position facing the pressure transfer roller via the photosensitive drum is placed between two fixed support rollers among the plurality of support rollers, so that the transfer roller is arranged There is no limit to
The conveyance route can also be freely set, and the device can be made more compact.

Moreover, there is an advantage that a stable image can be expected without image disturbance caused by the separation and separation of the pressure transfer roller.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view showing an embodiment of the present invention.
A perspective view of the latent image carrier unit in the embodiment shown in FIG.
3 is a sectional view of the latent image carrier unit in the embodiment of FIG. 1, and FIG. 4 is a partially enlarged sectional view showing an example of the photosensitive drum. In the figure, 10 is an optical printer, 11 is a main body, 12 is a photosensitive drum, 12a is a transparent substrate, 12b is a transparent conductive layer, 12c
1 is a photoconductor layer, 13 is a drive roller, 14 is a motor, and 15 is a photoconductor layer.
．． 16 is a fixed support roller, 17 is a movable support roller, 18
is the side plate, 19 is the mounting shaft, 20 is the coil spring, 21 is the LE
D head, 21a is an LED array, 22 is a focusing light transmitting body, 22a is an arm, 23 is a support member, 24 is a developing device, 25 is a magnet roller, 26 is a spike regulating plate, 27 is a gap roller, and 28 is a feeder. Paper roller, 29 is recording paper, 3
0 is a registration roller pair, 31 is a pressure transfer roller, 32 is a support shaft, 33° 36 is a separating claw, 34 is a heating roller, 35
is a pressure roller. Figure 3 Figure 4

Claims (1)

[Scope of Claims] A photoconductor drum that includes a transparent substrate, a transparent conductive layer and a photoconductor layer formed thereon, and that is moved in a predetermined direction, and that the photoconductor drum is in contact with the transparent substrate side. a plurality of support rollers for supporting movement in the predetermined direction; and an exposure device disposed on the transparent substrate side of the photosensitive drum and for exposing the photoconductor layer to light through the transparent substrate and the transparent conductive layer. and a light source for exposure, which is disposed on the photoconductor layer side of the photosensitive drum at or near the exposure position by the exposure light source, and selectively attaches toner to the surface of the photoconductor layer at the same time or immediately after exposure. and a transfer device having a pressure transfer roller that transfers the toner image formed on the outer surface of the photoreceptor drum onto recording paper, the image forming apparatus comprising: An image forming apparatus characterized in that a position facing the pressure transfer roller via the support roller is set between two fixed support rollers among the plurality of support rollers.