JPS6026965A - Dust preventing mechanism of led head - Google Patents

Abstract

PURPOSE:To stabilize a light amt. required for writing a latent image for a long term by installing an adsorbing member for catching a suspending toner through a magnetic or electrostatic attraction near a selfoc lens. CONSTITUTION:A suspending toner is attracted by electrostatic attraction and effectively caught with an adsorbing member 3 protruding forward from the front of a selfoc lens 2 in order to keep the front face of the lens 2 clean, prevent deterioration of a light amt. illuminating through the lens 2 and scattering of the light, and stabilize the light amt. of LED for writing a latent image for a long term. Or a magnetic adsorbing member 3 is installed near the lens 2 between the lens 2 and a developing device 6 to catch the toner attaching to the front face of the lens 2 and keep it clean. Since the suspending toner is caught with the member 3, the condensing lens 2 of the LED is not stained with the toner and prevented from deterioration and scattering of its light transmittance, thus permitting lont-term stabilization of LED intensity for writing the latent image.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a dust-proofing mechanism for a light source for forming a latent image using an LED and a self-off lens in an electrophotographic printing device using dry-component magnetic toner, and in particular, a dust-proofing mechanism for preventing contamination caused by toner. This relates to a dustproof mechanism.

When an LED is used as a light source for forming a latent image in an electrophotographic printing device, a self-off lens that focuses the LED light is installed between a charger and a developer arranged along the circumference of the photosensitive drum. However, this lens needs to be installed close to the photosensitive drum due to problems with optical characteristics. Therefore, powder toner scattered from the developing device and toner remaining on the surface of the photosensitive drum tend to adhere to the front surface of the self-off lens due to the influence of electrostatic attraction. Adhering toner causes a decrease in the amount of light transmitted through the self-off lens and variations in the amount of light, which lowers the effective efficiency of the self-off lens and causes uneven print density due to variations in the amount of light in printing.

The present invention solves the above problem by adsorbing and removing toner floating near the self-off lens, and stabilizing the amount of light for writing a latent image of an LED over a long period of time. That is, the present invention uses L as a light source for latent image formation.
An LED that uses an ED and is equipped with a self-off lens that focuses the light from the LED and irradiates it onto the circumferential surface of the photosensitive drum, located between a charging device and a developing device that are arranged along the circumferential surface of the photosensitive drum.
A dust-proofing mechanism for an LED head is characterized in that an adsorbent that captures floating toner by magnetic force or electrostatic attraction is installed near the self-off lens in the head.

Next, embodiments of the present invention will be described with reference to the drawings.

First, prior to explaining the embodiments, the developing and fixing process of the apparatus will be explained with reference to FIG. That is, in FIG. 1, a photosensitive drum 1 having a selenium coating layer on its outer peripheral surface
5 is rotatably installed, and as the photosensitive drum 15 rotates 150 times, the surface of the drum 15 becomes positively charged by the corona discharger 4 as a charger, and the surface of the photosensitive drum 15 becomes positively charged by the self-off lens 2. The light beam from the LED light source 1 is then focused. At this time, the charge in the area irradiated with the light disappears, and an electrostatic latent image is formed. A magnetic brush type developing device 6 is provided at a position advanced from the exposure position by the self-off lens 2 along the rotational direction of the photosensitive drum 150. A developing device cover 5 covers the upper part of the developing device 6. The electrostatic latent image on the photosensitive drum 15 is developed by coming into contact with the toner 7 that has been positively charged by the developing device 6 . Next, the developed image is transferred to paper 9 fed by paper feed rollers 8.8 disposed above and below.

Paper 9 is applied to the surface of photosensitive drum 150 and passes between photosensitive drum 15 and negative corona discharger (transfer) 10 . The negative charge applied to the paper 9 by the corona discharger (transfer) 10 transfers the magnetic toner 7 from the photosensitive drum 15 to the paper 9.
, thus paper 9. c) The image is fixed through the thermal pressure roller 11 and discharged out of the printing device 1. When the paper 9 carrying the image is removed from the drum and sent toward the thermal pressure roller 11, the photosensitive drum 15
continues to rotate, and the excess magnetic toner 17 is mechanically removed from the surface of the photosensitive drum 15 by the cleaning blade 13 and stored in the discharge toner box 12 .

The surface of the photosensitive drum 15 is then irradiated by a static elimination lamp 14 to erase the electrostatic latent image remaining on the photoconductive surface layer of the photosensitive drum 15.

In the above apparatus, until the drum 15 is charged again by the positive corona discharger 4, the toner slightly remaining on the surface of the photosensitive drum 15 loses its electrical attraction to the drum 15. In addition to being released from the surface of the photosensitive drum 150 and scattered around, toner is also scattered from the developing device 6 during development, and these toners are attached to the self-off lens 2 by electrostatic attraction.

Therefore, in the first embodiment of the present invention, as shown in FIG. An adsorbent 3 is installed near the off-lens 2. The front end 3a of the adsorbent 3 is a self-off lens 2.
protrudes forward from the front surface 2a of the absorber 3 to ensure an optical path for the light beam condensed by the self-off lens 2 within the absorber 3. Further, the adsorbing body 3 is grounded in order to adsorb the toner using electrostatic attraction force. Note that the cylinder 3 can be made of a conductor made of aluminum, copper, iron, or the like.

According to the present invention, the floating toner is effectively suctioned and captured by the adsorbent 3 which protrudes at least forwardly from the front surface of the self-off lens 2 due to electrostatic attraction force, before it adheres to the self-off lens. This prevents toner from adhering to the front surface of the lens 2, keeps the front surface of the self-off lens 2 clean, and prevents the amount of light emitted from the lens from decreasing or causing variations in the amount of light emitted from the LED.
The amount of light used to write latent images can be stabilized over a long period of time.

FIG. 2 is a diagram showing a second embodiment of the present invention.

In the previous embodiment, the floating toner was captured by the adsorbent 3 using electrostatic force, but the embodiment shown in Fig. 2 focuses on the fact that the floating toner is a magnetic material, and uses the magnetic force of the magnet. It is designed to trap toner. That is, an adsorbent 3 made of a magnet (permanent magnet or electromagnet) is disposed between the self-off lens 2 and the developing device 6, and the adsorbent 3 is installed near the self-off lens 2. The self-off lens 2 is kept clean by capturing toner adhering to the front surface of the self-off lens 2 with an adsorbent 3 using magnetic force.

As explained above, in the present invention, the floating toner is adsorbed and removed by the adsorbent, so that the self-off lens for condensing LED light is not contaminated with toner, and the amount of light transmitted through the lens is not reduced. It is possible to eliminate variations in the amount of light, and therefore it has the effect of stabilizing the amount of latent image writing light of the LED over a long period of time.

[Brief explanation of drawings]

FIGS. 1 and 2 are configuration diagrams showing embodiments of the present invention, respectively. 1...LED light source, 2...self-off lens, 3...
- Adsorption body, 4...Corona discharger, 5...Developer cover, 6...Developer, 7...Toner, 8...Paper feed roller, 9...Paper, 10...・Corona discharger, 11・
...Heat pressure roller, 12...Discharge toner box, 13
... Plaid cleaner, 14... Static elimination lamp, 15
...Photosensitive drum, Patent applicant NEC Corporation Representative Patent attorney Naka Kanno ゛1

Claims (1)

[Claims] (1) Using an LED as a light source for forming a latent image, the light from the LED is focused at an intermediate position between the charging device and the developing device arranged along the circumferential surface of the photosensitive drum and irradiated onto the circumferential surface of the photosensitive drum. 1. A dustproof mechanism for an LED head, characterized in that an adsorbent is installed near the self-off lens to capture floating toner by magnetic force or electrostatic attraction force.