JPS61143783A - Charge eraser for electrophotographic printing press - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention generally relates to a light-receiving surface that is charged to an appropriate level;
The present invention relates to an electrophotographic printing machine adapted to be subsequently exposed to light to form an electrostatic latent image of a document on a light receiving surface.

Electrophotographic printing methods generally involve charging a photoconductive member to a substantially uniform potential to render the surface of the photoconductive member sensitive. The charged portion of the surface of the photoconductive member is exposed to a light image of the original document to be reproduced. Does this mean that the area of information contained in the original document was statically placed on the photoconductive member? Record the li latent image.

After the electrostatic latent image is recorded on the photoconductive member, it is developed by applying a developer mixture to the electrostatic latent image.

This forms a powder image on the photoconductive member which is transferred to the copy sheet. Finally, the powder image is permanently fixed onto the copy sheet in the shape of an elephant.

1 trouble 1” υ? A problem with many conventional printing presses is that areas outside the image of the exposed document retain their original charge and are later developed. These areas include the edges as well as the areas between successive document images (interdocument gaps). These unwanted developed areas must be removed from the photoreceptive surface before the next charging and exposure cycle.

It is known in this art to use erasing lamps which are energized periodically to illuminate a predetermined area. The intensity and spectral output of this lamp is such that the charge level in the illuminated area is reduced below the level of the activation threshold of the device, thereby inhibiting development. These prior art lamps are typically C-Blue fluorescent lamps.
e fluorescent lamps), but are of relatively octavalent components that require expensive power supplies. These have other drawbacks such as start-up delays, stability problems due to temperature changes and reduced illumination at the end. An illumination source that avoids these problems is rare gas lamps, where a rare gas such as neon or xenon is used in place of mercury in fluorescent lamp systems. These lamps have been utilized in applications such as Instruction II, but have not been utilized as charge reduction devices in electrophotographic printing presses. Rare gas lamps have the advantage of being particularly useful in printing operations, exhibiting "instant start" characteristics and being more reliable in operation than fluorescent lamps. Rare lamps require far less power levels;
They cost twice as much as fluorescent lamps. Despite these advantages, rare gas lamps have traditionally not been used for printing, primarily due to their inadequate operating life. The type of printed stone listed here has been thousands of hours in the making to ensure reliability and maintenance standards! Requires a lamp with a lI life. Conventionally, it has been impossible to obtain a long service life and maintain a desired exposure level using rare gas lamps.

OBJECTS OF THE INVENTION It is therefore an object of the present invention to provide a charge reduction device for an electrophotographic printing press using rare gas lamps designed to meet long life requirements.

and 11) A photoconductive member, means for forming a charge on a surface area of said member, and exposing said surface area to light to form an electrostatic charge on said surface area. 12.05-3 comprising means for forming a latent image and means for reducing the charge on at least one region of the surface area, the means for reducing the charge having electrodes sealed at opposite ends;
It is characterized by an elongated tubular glass envelope containing neon gas at a pressure range of >3.5y/cIR2 (9-25 torr).

Other features of the invention will become apparent as the description proceeds.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a thorough understanding of the invention, reference is made to the drawings, in which like reference numerals refer to like elements. FIG. 1 depicts an electrophotographic printing surface incorporating features of the present invention. It will be seen from the following description that the apparatus of the invention is also suitable for use in a variety of printing processes different from those described above, and that the application of the invention is therefore not necessarily limited to the specific embodiments shown herein. It is clear that this is not the case.

Referring now to FIG. 1, a side view of an illustrative xerographic printing machine incorporating features of the present invention is shown.

As electrophotographic printing technology is well known, the fragmentation processing station is shown only schematically in FIG. 1 and its operation will be briefly explained with reference to FIG.

Processing module 14 uses a belt 30 having a photoconductive surface submerged on a conductive substrate.

Belt 30 preferably has the characteristics described in U.S. Pat. No. 4,265,990, the contents of which are incorporated herein by reference.

Belt 30 sequentially advances successive portions of the photoconductive surface through seed rod processing stations located at the intersection of its path of motion. Belt 30 is stretched around stripping roller 32, tension roller 34, and drive roller 36. Drive roller 36 is connected to a suitable motor (not shown) and rotated to advance belt 3o in the direction shown.

First, a portion of belt 3o passes through v1 electric station A. At charging station A, corona generating device 3
8 charges the photoconductive surface of belt 30 to a relatively high, substantially uniform potential.

After the photoconductive surface of belt 30 is charged, the charged portion thereof is advanced through exposure station B.

At the exposure station the original document is placed on a transparent platen 4o.

A lamp 42 projects a beam of light onto the original moon.

Light rays reflected from the original document are transmitted through lens 44 to form a light image of the original document. Lens 44 focuses this light image onto the charged portion of the photoconductive surface to selectively dissipate the charge on the photoconductive surface.

This action records an electrostatic latent image on the photoconductive surface that corresponds to the informational areas contained in the original document.

After the electrostatic latent image is recorded on the photoconductive surface of belt 30, belt 30 advances the electrostatic latent image to development station C, where magnetic brush development am converts the developed 81 material into the electrostatic latent image. Move forward to make contact.

Preferably, the magnetic brush developer assembly includes two magnetic brush developer tools 48 and 50. The Z roller advances the developer material into contact with the electrostatic latent image. These rollers form a stream of outwardly extending carrier particles and toner powder. The electrostatic latent image attracts toner powder from the carrier particles to form an image of the toner powder on the D electrostatic latent image.

After the electrostatic latent image is developed, belt 30 advances the dove powder image to transfer station D.

A sheet of support material 54 advances to transfer station D from a copy sheet stack (not shown). Transfer station D includes a corona generator 56 that injects ions onto the backside of the copy sheet.

This causes the toner powder image to wick from the photoconductive surface to the copy sheet. After transfer, the copy sheet moves onto conveyor 58, which advances the sheet to fusing station E.

Fusing station E includes a fusing assembly, generally designated 6o, which permanently affixes the transferred powder image to the copy sheet. Fusing assembly 6o preferably includes a heated fusing roller. In this manner, the toner powder image is permanently affixed to the copy sheet.

After arrival, the copy sheet is advanced to an output tray (not shown).

As the belt 30 continues to advance in the direction shown, it passes a cleaning station F where a cleaning roll 66 removes unwanted developer particles from the surface of the belt.

The printing surface shown in FIG. 1 requires some charge reduction to facilitate special functions.

Preliminary (Q charge erasing) is necessary to remove any charge remaining on the belt following the cleaning operation. Bunsenma Ryujo is necessary to erase the charged belt at the gate of the image of the document following the function. A pre-transfer eraser reduces the traction forces between the developed image and the belt surface (V) to facilitate transfer of the developed image, and an edge eraser removes unwanted charges. Required to remove from the edges of the image.

These functions are performed by a pair of neon quench lamps 70, 72 constructed and operated in accordance with the principles of the present invention. As shown in FIG. 1, these lamps are arranged in an interior space surrounded by a light-transmissive belt 30. The lamp 70 housed in the cavity 74 is optically coupled to the light pipe guide 76°78.80. Each of these light vibrator guides provides charge-reducing illumination to a particular portion of belt 30. The optical vibe guide 76 branches into two ends each having a width sufficient to erase charges at the edges of the image area. A light pipe guide 78 provides illumination for the transfer operation. Light pipe guide 80 provides illumination to aid in cleaning operations. lamp 70
The printing process is usually made to last for a period of 1 to 300 ms, giving the charged surface 300-600 ergs/cm''.

Lamp 72 is optically coupled to light guide 82 .

The output end of this guide 82 runs across the width of the bell 1-. Lamp 72 is automatically energized at some point of sufficient duration to erase the charge level of the area between the image plane portions of the subsequent document. Lamp 72 is approximately 50 ergs/C in the area between documents! A2
gives the erasure level.

In the preferred embodiment, the lamps 70,72 are 10
Contains an elongated glass envelope containing 0% neon gas. These lamps are of the cold cathode (filamentless 1-) type and have a diameter of 10+ m and a length of 485 mm. These lamps are 28.2FJ/cps2 (21torr)
(7) It is operated at an operating current between 10 and 501a (rms), but preferably at 35 ma. When operated under these conditions, lamp 70.
72 has been found to exhibit lifetime characteristics that far exceed those possible when operating conventional fluorescent lamps or conventional rare gas lamps at lower pressures. These lamps have been found to retain excellent stability over time and under varying temperature conditions.

These lamps also have instantaneous ignition properties and Figures 2 to 4 are drawn to illustrate these characteristics. l
T! It is a diagram.

FIG. 2 is a diagram showing the relative light output of the lamp over a 2400 hour UJR life. The input power of the lamp is 3
Qma was 10 watts, and the ambient temperature was 25°C. The lamp output was measured at a distance of 250 mm from the axial center of the lamp. Light output is shown in nominal units, but averages 350 ergs/c for the device shown.
It is possible to output tn2, and the fluctuation is ±2 over the operating life.
%.

FIG. 3 is a diagram showing the uniformity of the lamp in the axial direction.

The axial emission was measured at a point 20 m from the surface area of the lamp. Plot A shows the performance of the neon lamp before the life test, and plot B shows the performance after the life test. Both lamps showed very little loss of illumination at the end, and the life tested lamp showed only a little loss compared to the new lamp.

Figure 4 is 15.6~43.3℃ (60~110"F)
FIG. 3 is a diagram showing the relative output change with respect to the operating temperature in the range of . These lamps exhibited output stability within ±5%, well within the tolerances required for commercial printing reeds.

According to one feature of the invention, it has been found that operating the lamp at relatively high pressure levels significantly contributes to the operational life of the lamp. It has been found that the trade oH when operating at such pressures (high emf, low light output) is acceptable, as shown in FIG. This is because the light output is sufficient for the required erasure purpose and the long life of the lamp fully compensates for the slightly reduced efficiency (when compared to operating at lower levels). Because there is. As an example, a neon lamp matching a lamp 70°72 in all respects except that it is operated with a 12.059/cR2 (9 torr) (D'1 force) has an operating life of 250 hours. 12.05~33.5g/C!R2(
A pressure range of 9-25 torr has been found to provide satisfactory lifetime performance for most machine requirements.

In conclusion, while exemplary embodiments of the charge reduction lamp of the present invention have been described, it is contemplated that various other variations and modifications may be made within the knowledge of those skilled in the art. For example, although the preferred embodiment is a 100% neon gas lamp, small amounts (about 1%) of other gases such as xenon can be added.

For the purposes of the present invention, the lamp envelope is
It must be able to accommodate virtually 100% neon, even with incremental component addition modifications of haze. As a second example, lamp 70. shown in FIG.
72 is of a filamentless type, but the second embodiment of the lamp can include a "heating" filament to increase the level of brightness.

Effects of the Invention As described above, the present invention eliminates all the drawbacks of the conventional device and uses rare gases designed and designed to meet the long life requirements ('1). Thus, it is possible to provide a charge reduction device for electrophotographic printing machines that use lamps.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing an electrophotographic printing machine incorporating the electronic erasing device of the present invention. FIG. 2 is a diagram illustrating the performance of an operation constructed in accordance with the principles of the present invention; FIG. 4 is a diagram showing the relative light output variation over a temperature range. FIG. 5 is a diagram showing the variation of reflected light output over a pressure range. 14... Output module 30... Belt 32... Peeling roller 34... Tension roller 36... Drive roller 38.56... Corona generating device 4o... Platen 42... Lamp 44... ... Lens 48.50 ... Magnetic brush roller 54 ... Supporting material sheet 58 ... Conveyor 60 ... Fusion assembly 66 ... Cleaning roll 71.72 ... Neon erase lamp 76.78 .80...Light pipe guide 82...Light guide A...Charging station B...Exposure station C...Development station D...Transfer station E...m? 1st Station F...Sei i Station

Claims (1)

[Claims] a photoconductive member, means for forming a charge on a surface of said member, means for exposing said surface to form an electrostatic latent image on said surface, and reducing the charge on at least one region of said surface. 12.05-3, the means for reducing the charge having electrodes sealed at opposite ends.
An electrophotographic printing machine characterized in that it includes an elongated tubular glass envelope containing neon gas at a pressure range of 9 to 25 torr.