JPS60111270A - Developing device - Google Patents

Abstract

PURPOSE:To employ either a developing brush development system or a cascade development system according to the kind of an original or an operator's choice by switching both systems. CONSTITUTION:The interval between the front end part 9'' of a guide plate 9 and a sleeve 4 is varied to perform developing operation by using a single developing device while the magnetic brush development system and cascade development system are switched easily. An electromagnet is used as a magnetic pole facing a photosensitive body among magnetic poles of a magnetic roll 3, and the electromagnet is excited when the guide plate 9 separates from the magnetic roll 3 and not excited when the guide plate 9 is switched to contact the magnetic roll 3. Consequently, a powder developer falling on the photosensitive body 1 is not influenced by the magnetic force of the magnetic roll 3 during the development by the latter cascade development system, so more natural excellent cascade development is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a developing device for an electrophotographic copying machine using a powder developer.

[Technical background]

Conventionally, as a developing method for an electrophotographic copying machine using a powder developer, a cascade developing method is disclosed in U.S. Pat. No. 2,618,551, etc., and a magnetic brush developing method is disclosed in U.S. Pat. No. 2,786,441, etc., and these are known techniques. It is being

By the way, the cascade development method has an extremely strong edge effect, so it has excellent reproducibility for line originals, but it has the disadvantage that the center part of the original is not reproduced at all.On the other hand, the magnetic brush development method Although the reproducibility of solids is good due to the electrode effect, the reproducibility of lines, especially lines parallel to the longitudinal direction of the magnetic roll such as horizontal ruled lines, is poor.

Therefore, various proposals have been made to improve the developability of solids in the cascade development method, and to improve the developability of lines in the magnetic brush development method, but the above drawbacks are:
Since all of these problems are related to the fundamental problems of each developing method, it is not easy to improve them, and no effective solution has yet been proposed. Although the above problem can be solved by providing a plurality of developing devices and using both developing methods in combination, the problem arises that the main body of the copying machine becomes larger and more expensive.

[Purpose of the invention]

The present invention enables a single developing device to selectively switch between a magnetic blasto development method and a cascade development method, or both, depending on the type of document. It is an object of the present invention to provide a developing device capable of obtaining desired image quality.

[Summary of the invention]

The present invention provides a magnetic plan development device including a doctor grade and a non-magnetic cylindrical sleeve rotatably provided to surround a magnetic roll. A kite plate is provided in which the distance between one end and the sleeve can be changed, and the developing operation can be performed by switching between the magnetic brush developing method and the cascade developing method, and these developing methods can be used in combination. It is something to do.

[Embodiments of the invention]

Examples of the present invention will be described below. First, an example of the configuration of a developing device of an electrophotographic copying machine to which the present invention is applicable will be described with reference to FIG. In the figure, 1 is a photoreceptor for holding an electrostatic latent image, 2 is a main body of the developing device, 3 is a magnetic roller having a plurality of magnetic poles on its surface, and 4 is the magnetic roller 3.
A non-magnetic cylindrical developing sleeve is rotatably disposed around the periphery of the photoconductor I, and is disposed so as to face the photoreceptor I. 5
1 is a doctor blade, 6 is a bucket roller for stirring the developer, and 7 is a toner supply roller for supplying toner from a toner dropper 8.

In the developing device composed of such structural members, the powder developer is conveyed in the direction of the arrow as the sleeve 4 rotates while being attracted to the surface of the sleeve 4 by the magnetic force of the magnetic roll 3. After being regulated to a constant layer thickness by the blade 5, it is transported to the developing section facing the photoreceptor 1, where it forms spikes and rubs the electrostatic a(&) previously formed on the photoreceptor 1. , so-called magnetic brush development is performed to visualize the electrostatic a image.The powder developer on the sleeve 4 after being rubbed on the photoreceptor 1 is placed between the magnetic poles of the magnetic roll 3 of the same polarity. When the developing agent reaches the part where it is, it naturally falls from the surface of the sleeve 4, and the fallen developer is conveyed in the direction of the arrow by the bucket roller 6, and is again attracted to the sleeve 4, and the same operation is repeated.Meanwhile, The toner supplied from the toner hopper 8 by the toner supply roller 7 is
Mixed with powder developer by bucket roller 6,
It is designed to be supplied to the developing sleeve 4.

FIGS. 2(5) and (I3) are enlarged cross-sectional views of essential parts of an embodiment in which the present invention is applied to the developing device shown in FIG. 1, and each shows a mode in which different developing operations are performed. It is. In the drawings, parts denoted by the same reference numerals as those shown in FIG. 1 indicate the same constituent members.

In FIG. 2 (5) and (-), 9 is a guide plate, one end 9' of which is rotatably attached to the main body of the apparatus, etc. at a position close to the photoreceptor 1, and the other end of which is rotatably mounted. 9'' is placed close to the doctor blade 5, and the rotating tip 9
The position where the distance g between the doctor blade 5 and the sleeve 4 is greater than the gear knob d between the doctor blade 5 and the sleeve 4, and the position where the rotating tip 9'' contacts the sleeve 4. The guide plate 9 is configured to be tilted toward the photoreceptor 1 even when the tip end 9'' is in substantially contact with the developing sleeve 4, which can be selected.

When the guide plate 9 is at a position where the distance g between its tip 9'' and the sleeve 4 is set to be equal to or larger than the gear 716 between the doctor blade 5 and the sleeve 4, as shown in FIG. 2(5), A so-called magnetic plano phenomenon occurs.That is, the powder developer on the sleeve 4, which is regulated to a layer thickness d by the doctor blade 5, passes below the guide plate 9 without contacting it. The toner is conveyed toward a magnetic pole position opposite to the photoreceptor 1, and is developed by forming spikes at this position and rubbing the electrostatic latent image on the photoreceptor.

On the other hand, as shown in FIG. 2 (I3), when the tip 9'' of the guide plate 9 is in a position where it is in close contact with the surface of the sleeve 40, cascade development is performed. The regulated powder developer is scraped off from the sleeve 4 by the tip 9'' of the guide plate 9, flows down on the inclined guide plate 9, and reaches the shafted end 9.
' falls onto the photoreceptor 1. The electrostatic latent image is developed by flowing the developer onto the photoreceptor.

As described above, by changing the distance between the tip 9'' of the guide plate 9 and the sleeve 4, development can be easily switched between the magnetic brush development method and the cascade development method using a single development device. If this switching operation can be performed by operating a button on the operation panel, it can be changed depending on the type of document (documents with many solid parts, documents with many lines, etc.) or the operator's preference. Both developing methods can be easily selected and used, and copies with desired image quality can be easily obtained.

In this embodiment, at least one of the magnetic poles of the magnetic roll 3 facing the photoreceptor is an electromagnet, and when the guide plate 9 is in the position shown in FIG. 2 (2), the electromagnet is excited, and the guide plate 9 If the configuration is such that it will not be excited when it is switched to the position shown in Figure 2 (Bl), then Figure 2 (B
) When developing using the cascade development method shown in
Since the powder developer flowing down on the photoreceptor 1 is not affected by the magnetic force of the magnetic roll 3, more natural and good cascade development can be performed.

FIG. 3 is a diagram showing another embodiment of the present invention. In this embodiment, the distance g between the tip end 9'' of the guide plate 9 and the sleeve 4 is
The structure is such that ' can take any value between zero and d. As described above, when the guide plate 9 is in the intermediate position as shown in FIG. The portion is scraped off, the layer thickness g' is regulated to be thin, and the layer is conveyed by a sleeve 4, and the electrostatic latent image on the photoreceptor is rubbed and developed with a magnetic brush.Meanwhile, the guide plate 9
The remaining part of the developer scraped off by the developer flows down on the guide plate 9 and falls onto the photoreceptor 1 from the shafted end 9'.
Cascade development is performed by flowing down onto the photoreceptor l.

In this way, by setting the guide plate 9 at an appropriate intermediate position, it is possible to simultaneously perform development that combines the features of both the magnetic brush development method and the cascade development method. Therefore, in terms of image quality, the development according to this embodiment has both solid reproducibility and line reproducibility reaching a certain level, and has excellent gradation reproducibility, so it can be used for originals with many halftones such as photographic originals. suitable for copying.

The displacement of the guide plate 9 in this embodiment can be easily and arbitrarily set using a simple mechanism as shown in FIG. That is, in FIG. 4, reference numeral 11 denotes an operation panel supported by the main body wall 10, and an operation knob 12 is provided on the operation panel 11. A slider 13 is fixed to this operating knob 12, and the lower tip of the slider 13 is fixed to a pivot shaft 14 of the kite board 9, and is biased upward by a spring 16. The tapered member 15 is configured to abut against the tapered surface of the tapered member 15. In the operating mechanism configured in this way, when the operating knob 12 is slid left and right, the tip of the slider 13 also slides left and right on the tapered surface of the tapered member 15. By sliding the tip of the slider, the tapered member 1
5 is moved up and down, thereby causing the guide plate 9 to rotate around the rotation support shaft 14. Therefore, one operation
By simply sliding the mirror J2, the guide plate 9 can be set to an appropriate intermediate position, making it easy to obtain a copy with the desired image quality.

〔Effect of the invention〕

The present invention provides a magnetic plan developing device in which one end is located near the doctor blade and the other end is located near the photoreceptor between the doctor blade and the developing area, and the distance between the one end and the sleeve can be changed. A guide plate has been installed to allow a single developing device to be operated by switching between the magnetic brush developing method and the cascade developing method. By adopting either of these methods, you can obtain a copy with the desired image quality. Furthermore, since both developing methods can be used in combination, it is possible to obtain a copy image with excellent gradation reproducibility that combines the features of both methods.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of an example of the configuration of a developing device of an electrophotographic copying machine to which the present invention can be applied, and FIGS. 2 (5) and (I3) show an example of the developing device according to the present invention. FIG. 3 is an enlarged view of the main part of another embodiment of the present invention, and FIG. 4 is an enlarged view of the guide plate drive mechanism of the device shown in FIG. 3. It is a schematic diagram showing one example of composition. In the figure, 1 is a photoreceptor, 2 is a main body of the developing device, 3 is a magnetic roll, 4 is a sleeve, 5 is a doctor blade, 6 is a bus gap roller, 7 is a toner supply roller, 8 is a toner presser, 9 is a guide plate, 11 1 is an operation panel, 12 is an operation knob, 13 is a slider, 14 is a guide plate rotation shaft, 15
indicates a tapered member. Patent Applicant: Olympus Optical Industry Co., Ltd. Representative Patent Attorney Kenji Mogami JJIk No. 1 Figure 2 Figure 2 (A) (B) 3 Kanto Figure 4 Procedural Amendments 1995 Shin-Mon ↓ Japan Patent Office Commissioner Kazu Wakasugi Husband 1, Indication of the case 1982 Patent Application No. 218692 2, Title of the invention Developing device 3, Person making the amendment 4, Agent 8, Contents of amendment (1) The scope of claims is amended as shown in the attached sheet. . (2) "Bass nod roller" on page 12, line 15 of the specification is corrected to "bucket roller." Claims (() A magnetic roll having a plurality of magnetic poles on its surface and fixedly installed in close proximity to a photoreceptor, and a powder developer on the surface of the magnetic roll, which is rotatably provided so as to surround the magnetic roll. a non-magnetic cylindrical sleeve capable of adsorbing and transporting the powder developer; a doctor blade regulating the layer thickness of the powder developer transported by the sleeve; one end located near the doctor blade, and the other end located near the photosensitive a guide plate located near the doctor blade and arranged at an angle so as to allow the powder developer to flow down onto the photoreceptor; the distance between the guide plate located near the doctor blade and the sleeve is adjusted; A developing device characterized in that it is configured to be changeable. (2) A distance between one end of the guide plate and the sleeve is
2. The developing device according to claim 1, wherein the developing device is configured to be able to change the distance between approximately zero and the distance between the doctor blade and the sleeve. (3) The developing device according to claim 1 or 2, wherein the guide plate is arranged so as to be rotatable about the other end near the photoreceptor. (4) The magnetic roll has a magnetic pole facing the photoconductor formed of an electromagnet, and when the distance between the guide plate and the sleeve is approximately zero, the electromagnet is not excited, and the distance is 4. The developing device according to claim 1, wherein the developing device is configured to be energized when the distance between the blade and the sleeve is greater than or equal to the distance between the blade and the sleeve. (5) The developing device according to claim 1, wherein the distance between the guide plate and the sleeve is configured to be continuously changeable by moving an operation knob provided on an operation panel. Device.

Claims (5)

[Claims] (1) A magnetic roll having a plurality of magnetic poles on its surface and fixed close to the photoreceptor, and a rotatable magnetic roll surrounding the magnetic roll, and a powder developer is adsorbed onto the surface of the magnetic roll. a non-magnetic cylindrical sleeve that can be conveyed; a doctor blade that regulates the layer thickness of the powder developer conveyed by the sleeve; one end of which is located near the doctor blade;
The other end includes a guide plate located near the photoreceptor and arranged at an angle so that the powder developer can flow down onto the photoreceptor; the guide plate located near the doctor blade; A developing device characterized in that a distance between the developing device and the sleeve can be changed. (2) The distance between one end of the kite plate and the sleeve is configured to be changeable to substantially zero or greater than the distance between the doctor blade and the sleeve. developing device. (3) The developing device according to claim 1 or 2, wherein the guide plate is arranged so as to be rotatable about the other end near the photoreceptor. (4) The magnetic roll has a magnetic pole facing the photoconductor formed of an electromagnet, and when the distance between the guide plate and the sleeve is approximately zero, the electromagnetic field is not excited, and the distance is 4. The developing device according to claim 1, wherein the developing device is configured to be energized when the distance between the blade and the sleeve is greater than or equal to the distance between the blade and the sleeve. (5) The developing device according to claim 1, wherein the distance between the kite plate and the sleeve is configured to be continuously changeable by moving an operation knob provided on an operation panel. Device.