JPH04130390A - Image forming device - Google Patents

Abstract

PURPOSE:To efficiently and accurately regulated and adjust a focal distance and a developing gap by fixing the regulating of a gap between a developing means and a photosensitive drum and setting a regulation reference surface at the outer peripheral surface of the drum. CONSTITUTION:In order to regulate the developing gap, positional regulation is directly performed by setting the outer peripheral surface of the drum as reference, so that the regulation of the gap is accurately performed without considering the accumulated error of assembling and the error of parallelism in an axial direction even when the photosensitive drum is like a hollow sleeve. Furthermore, since regulation is fixed regulation, the gap can be automatically set by exchanging/reloading a developing unit and stably regulated with high accuracy over a long term. Meanwhile, the focal distance is adjusted by taking the outer peripheral surface of the drum on a developing position side corresponding to an image-formation position even on an exposure side as reference, so that the reference surface corresponds to the image-formation position and the focal distance is accurately adjusted without being influenced by the out-of- roundness of the drum, thereby improving image quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an image forming apparatus using a photosensitive drum formed by laminating a transparent conductive layer and a photoconductor layer on a transparent support.

"Prior Art" Conventionally, exposure means generates light output corresponding to image information on the inner peripheral side of a photoreceptor drum, which is formed by laminating a light-transmitting conductive layer and a photoconductor layer on a light-transmitting support. and simultaneously or immediately after focusing the light output of the exposure means to form a latent image on the photoconductor layer, the latent image is developed through a developing means disposed facing the photoreceptor drum. Visual image (toner JsA)
An image forming apparatus is known that is configured to be able to transfer the toner image onto plain paper via a transfer roller or other transfer means after the toner image has been converted into a toner image. (Japanese Unexamined Patent Publication No. 58-153957, etc., hereinafter referred to as a back exposure device) In this type of image forming device, unlike a known electrophotographic device in which an exposure means is arranged on the outer peripheral surface of a photoreceptor drum,
Since the exposure means is inserted and fixed into the photoreceptor drum and the photoreceptor drum is rotated, it is extremely troublesome to set the focal distance between the photoreceptor drum and the exposure means. In order to perform development almost simultaneously, it is necessary to adjust the development gap at the same time at the exposure position, and as a result, if one interval is adjusted, the interval regulation of the other will be deviated, and the three units cannot be accurately spaced. It was quite difficult to configure.

For this purpose, for example, according to the technique shown in Japanese Patent Application Laid-Open No. 2-141774, three support rollers are attached to an exposure head integrated into the drum so that they can be inscribed on the inner peripheral surface of the drum. The supporting roller located on the side facing the white developing roller is fixed, thereby fixedly setting the focal distance between the photosensitive drum and the exposure means, and also aligning the head with the axis using the three rollers. While the drum is rotatably positioned and fixed around the drum unit, a gap adjusting member is disposed between the drum unit and the developing roller, and the developing gap is adjusted using the gap adjusting member.

``Technical problem to be solved by the invention'' However, according to the prior art, the printer head is composed of a combination of a plurality of members, namely an LED head and a focusing lens, and is positioned on the inner peripheral surface of the drum via a fixed support roller. Because of the supporting structure, assembly errors are inevitably likely to occur, and it is important to place fixed position regulating means in areas where such assembly errors are unavoidable in order to improve image clarity. It's not a good idea.

However, the focal length accuracy must be determined between the photoconductor layer located on the surface of the photoreceptor drum and the focusing lens, but as mentioned above, the fixed support roller is used to set the inner peripheral surface of the drum to the reference position. Because of the configuration in which the image forming apparatus is set as follows, the imaging error tends to vary due to the rotation of the drum, which is influenced by variations in the diameter of the rollers and the roundness of the drum.

In addition, in the above technology, the focal length side of the exposure means is fixed, and the distance on the developing gap side is adjustable, but the developing unit needs to be removed as appropriate for color changes, toner replacements, etc., and the distance is adjusted each time the developing unit is replaced. Making adjustments imposes an excessive burden on the user.

However, although it is important to maintain the developing gap with high precision between the developing roller and the outer peripheral surface of the drum, in the above technology, since the photosensitive drum is shaped like a hollow sleeve, the photosensitive drum is inserted into the drum. Since the fixed shaft of the printer head is used instead to adjust the distance between the shaft and the rotating shaft of the developing roller, it is not always possible to accurately adjust the distance due to cumulative errors of these members. In particular, since the drums etc. extend long in the axial direction,
A problem arises in that the development gap cannot be maintained with high precision in the axial direction.

SUMMARY OF THE INVENTION In view of the drawbacks of the prior art, it is an object of the present invention to provide an image forming apparatus that can regulate or adjust the focal length and development gap most efficiently and with high precision.

``Technical Means for Solving the Problems'' The present invention differs from the prior art in that the gap between the developing means and the photoreceptor drum is fixed, and the regulation reference surface is the outer peripheral surface of the drum.

In this case, the regulating means may be a roller provided around the outer circumferential surface of the developing roller, or a pair of support rollers supported by a housing and disposed on both sides of the developing position may be used as shown in the embodiment described later. Good too.

The second feature is that the distance between the photosensitive drum and the exposure means can be adjusted using the outer peripheral surface of the drum as a reference surface.

Such an adjusting means is, for example, an adjusting means disposed substantially along a line connecting the exposure position and the drum axis while regulating the position of the developing position side of the outer circumferential surface of the photoreceptor drum using the roller or fixed support roller. The exposure means may be configured to be movable by utilizing the exposure means.

"Operation" According to this invention, since the position of the developing gap is directly regulated using the drum outer peripheral surface as a reference, even if the photoreceptor drum is in the shape of a hollow sleeve, it is possible to eliminate cumulative assembly errors, axial parallelism errors, etc. Accurate gap regulation is possible without any consideration, and since the regulation is a fixed regulation, the interval can be automatically set even when the developing unit is replaced/reinstalled, ensuring high precision and stability over a long period of time. gap regulation becomes possible.

On the exposure side, on the other hand, the focal ratio M is adjusted based on the outer circumferential surface of the drum on the developing position side, which corresponds to the image forming position. Since it is not affected by the roundness of the lens, it is possible to adjust the focal length with high accuracy, and the image quality can be improved.

However, since the support rollers, rollers, etc. that serve as the standard regulating means are arranged on the outer circumference of the drum, and no rollers are inserted on the inner circumference, in other words, there is no exposure inside the drum. Since only the minimum necessary components such as the charge eliminating means and the static eliminating means are inserted, it is possible to easily reduce the diameter of the photosensitive drum.

Further, according to the present invention, since the exposure means side, which cannot avoid assembly errors caused by a plurality of members, can be adjusted in position, it is extremely advantageous in improving image clarity.

"Embodiments" Hereinafter, embodiments of the present invention will be described in detail by way of example based on the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this example are merely illustrative, and are not intended to limit the scope of the invention, unless otherwise specified. Just an example.

FIG. 2 shows the overall configuration of an image forming apparatus according to an embodiment of the present invention, in which 1 is a photoreceptor drum, and a drum-shaped light-transmitting support Ia is provided with a light-transparent conductive layer 1b and a photoconductor layer 1c. It is formed by laminating layers, and is configured to be rotatable in the direction of the arrow by a drive roller 11, which will be described later.

Reference numeral 2 denotes an exposure unit inserted into the photoreceptor drum 1, which includes an LED array 22 that generates light output corresponding to image information and a focusing lens 23 ( An exposure system consisting of a selfoc lens (trade name: SELFOC lens) and an eraser 24 on the opposite side in the circumferential direction of the support body 21 are fixedly arranged to extend over the entire axial direction of the photoconductor. There is. The image forming position of the exposure system is configured so that the image is formed on the photoconductor layer IC located on the focal line connecting the axes of the photosensitive drum 1 and the developing roller 31, which will be described later.

Reference numeral 3 denotes a developing device, which has a toner container 32 containing conductive magnetic toner with an opening on the side facing the photosensitive drum l, and a developing roller 31 that includes a fixed magnet assembly 34 in the opening 33.
As shown in FIG. Although the developing roller 31 regulates the developing gap by a spacing regulating roller 3A provided around the circumference, it is not always necessary to use such a roller 3A.
It is also possible to adjust the gap between the fixed support rollers 12 and 13, which will be described later, and the developing roller shaft 31a engaged with the guide groove 51 without using the.

Returning to FIG. 2, in the device, by rotating the developing roller 31 in the direction of the arrow, the toner whose layer thickness is regulated by the doctor blade 36 formed on the side of the container 32 corresponds to the imaging position of the exposure system. After being guided to a developing position and developing the latent image formed on the developing position, the toner image carried on the photosensitive drum 1 is guided to the transfer roller 4 side as the drum 1 rotates. After the toner image is transferred onto the inserted plain paper at a proper timing by the registration roller 5, the transferred unfixed toner image is fixed by the fixing roller 6 and then ejected onto the paper ejection tray 7.

On the other hand, after the toner transfer, the photoreceptor drum 1 is erased by an eraser 2.
After being neutralized in step 4, the toner is led to the developing position again, and the residual toner is removed by rubbing with the toner just before the developing position, and the above operation is repeated.

Note that 8 is a paper feed roller that guides the plain paper stacked in the paper feed cassette 9 to the registration rollers 5.

Now, the exposure unit 2 includes an exposure system consisting of an LED array 22 and a focusing lens 23 on a support 21 made of a non-transparent insulating material, and on the opposite side in the circumferential direction with the support 21 in between. An eraser 24 is fixedly disposed at a position extending over the entire axial direction of the photoreceptor, and the eraser 24 is
An insulating cover member 25 having a semicircular arc cross section is attached to cover the outer peripheral side of the support body 21 located between the lens 4 and the focusing lens 23, and the cover member 25 and the support body 21 create two divided air spaces 26a, 26b, and the LED row 22 and the eraser 2 are placed in the divided air spaces 26a and 26b.
The optical path of the focusing lens 23 is set in the radial direction passing through the axis of the central axis 29 provided at both ends, and the area outside the image area of the unit is accommodated. A spacer with a diameter slightly smaller than the inner diameter of the drum is interposed in the drum, and as will be described later, even when the support roller of the photoreceptor drum l is released, the photoreceptor drum will not fall off and will not come into contact with the exposure unit due to the spacer 28. It is constructed so that it can be supported in a hollow state.

As shown in FIG. 3, the exposure unit 2 has a positioning width so that the distance can be adjusted in the non-axis direction by a pair of focal length adjustment plates 47 which are screwed to the housing 41 via a central axis 29 provided at both ends. supported.

As shown in FIG. 1, the focal length adjusting plate 47 is arranged along the focal line corresponding to the optical path of the condenser lens, in other words, along a line that connects the drum exposure position and the drum axis, with the axis sandwiched between the axis. A pair of oval long holes 47a are bored at symmetrical positions on both sides, and a bottle 41b standing from the housing 41 is engaged with the long holes 47a. In this case, the bin 4
1b is formed to have the same diameter as the lateral width of the elongated hole 47a.

Incidentally, reference numeral 45 denotes an angle adjustment plate attached on the focal length adjustment plate 47, and the center hole 45a of the angle adjustment plate 45 is fitted to the four ends of the D-cut central axis, and the center hole 4
The center hole 45a is located at an arbitrary location separated by a predetermined pressure from 5a.
An angle adjustment hole 45b formed in an arc shape with the center at the center is bored, and a screw 641a is bored at a predetermined location of the focal length adjustment plate 43 corresponding to the adjustment hole 45b.

On the other hand, as shown in FIG. 1 and FIG. The photosensitive drum l is rotatably supported while maintaining the gap with the developing roller 31 with high precision by supporting it at three points with the swinging drive roller 11.

To explain its structure, fixed support rollers 12 and 13 are arranged on both sides of the developing position in the circumferential direction, in contact with the outer circumferential surface of the photoreceptor drum 1, and at almost symmetrical angles (for example, the distribution angle is 30 degrees). The supporting rollers 12 and 13 are brought into contact with the outer circumferential surface of the photosensitive drum l located on both ends in the axial direction away from the respective image areas, and are pivotally supported by the housing 41.

On the other hand, the swing drive roller 11 is arranged so that its contact position coincides with the line passing through the development position and the center of the drum via the swing plate I4, which is elastically biased toward the development position by a spring 15. do.

In this case, the swing plate 14 is swingably supported on the rotating shaft of a relay gear 16b which transmits rotational force in synchronization with the shaft gear of the transfer roller 4 and the shaft gear 16C of the swing drive roller 11, which will be described later.

The swing plate 14 is fixed to a lever member 19 that is biased by a click-clack spring 18, and by rotating the lever member 19 in the direction of the arrow, the drive roller is moved through the lever member 19. 11 can be released from pressure contact with the photoreceptor drum l, and can be fixed at a lower position in a separated state.

The transfer roller 4 includes the drive roller 11 and the support roller 12,
13, and is biased by a spring 17 so as to be able to come into pressure contact with the photosensitive drum 1 side.

16a- is a relay gear train, which drives the motor shaft gear 16A via the fixing roller shaft gear 16a/relay gear 16b, and connects the shaft gear 16C11 of the drive roller 11 and the transfer roller 4 to each shaft gear 16C11.
6b, and both rollers II and 14 are configured to be able to rotate synchronously.

Next, the method for assembling each of the above devices will be explained. First, the lever member 1 is biased by the click-clack spring 18.
9, the developing device 3 is moved to a predetermined position using the guide groove 51 formed on the housing 41 side and the developing roller shaft 31a engaged with the guide groove 51, as shown in FIG. After mounting, the exposure unit 2 is temporarily held with the photoreceptor drum l via the spacer 28, and the unit 2 is fixed with a film between the housing 41 via the central axis 29 and the focal length adjustment plate 43. By raising the lever member 19, the drive roller 11 is elastically biased by the spring 15 and is pressed against the outer peripheral surface of the photoreceptor drum l.
- Since the pair of fixed support rollers 12.13 and the roller 3A, which are pivotally supported by the housing 41, are present on the force image positioning side, the roller 3A regulates the developing gap and the roller 3A.
A and fixed support rollers 12 and 13 regulate the position of the photosensitive drum.

After the position is regulated, the exposure unit 2 is moved in the focal direction through the focal length adjustment plate 47 while the position is regulated in the short direction of the elongated hole 47a by the bin 41b, and the focal length is adjusted. , the distance adjustment plate 47 is fixed by a screw 48 screwed into the bracket 47d, and since the angle adjustment plate 45 is movable integrally with the focal length adjustment plate 47, the focal length can be adjusted by the adjustment plate 47. After adjustment, the development position and the exposure position can be easily matched in the circumferential direction by swinging the vaginal angle adjusting plate 45 in the circumferential direction, and after the matching, the screws 46 are screwed into the screw holes 41a to fix them. do it.

Therefore, according to this embodiment, the effects of the present invention can be smoothly achieved.

``Effects of the Invention'' As described above, according to the present invention, the focal length and the developing gap can be regulated or adjusted most efficiently and with high precision, and in particular, even when the unit of each device is replaced, the Regulations and adjustments can be made with precision.

It has various effects such as

[Brief explanation of drawings]

Fig. 2 is an overall configuration diagram of an image forming apparatus according to an embodiment of the present invention, Fig. 3 is a side view showing the mounting state of the photosensitive drum incorporating the exposure unit, and Fig. 4 is its drive system. FIG. 1 is a schematic assembly diagram showing the support state of the photoreceptor drum and the angle adjustment mechanism of the exposure unit.

Claims (1)

[Scope of Claims] 1) An exposure means for forming a latent image is provided on the inner circumferential side of a photosensitive drum formed by laminating a translucent conductive layer and a photoconductor layer on a translucent support, and an exposure means for forming a latent image is provided on the outer circumferential side. In an image forming apparatus configured such that a developing means is disposed in the photosensitive drum, and the developing means performs toner development by the developing means simultaneously with or immediately after exposure by the exposure means while rotating the photosensitive drum, the developing means and the photosensitive drum being rotated. The distance between the photoreceptor drum and the exposure means is adjusted as a fixed distance, while the distance between the photoreceptor drum and the exposure means is adjustable, and both of the above restrictions are performed using the outer peripheral surface of the drum as a reference surface. An image forming apparatus characterized by: 2) regulating the position of the outer circumferential surface of the photoreceptor drum on the developing position side, and using an adjusting means disposed substantially along a line connecting the exposure position and the drum axis; The image forming apparatus according to claim 1, wherein the exposure means is configured to be movable.