JPH0424657A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent lowering of quality of an image by providing a toner level sensor detecting toner quantity inside a hopper and a control means which stops a replenishing roller when the toner quantity inside the hopper is below a specified value. CONSTITUTION:A toner level sensor 15 for detecting the toner quantity inside the hopper 10 is installed in the hopper 10. The toner quantity inside the hopper 10 is monitored by the toner level sensor 15, and when the toner quantity is below a specified value, the replenishing roller 13 is forcedly made to be a stopped state by a control part 20 functioning. Therefore, inconvenience such as the recovered toner inside a chamber 12 to be imparted to a toner container 2 side, also, through the hopper 10 and reused before being recovered to an initial state is prevented. Thus, an always stable quality of image can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus such as an electronic copying machine or a printer.

In these image forming apparatuses, at least a charger, an exposure means, a transfer means, and a cleaning means are generally arranged around a base such as a photoreceptor drum in order from the upstream side in the direction of movement of the base. However, the disadvantage is that the overall size is large and the cost is high.

Therefore, recently, an image forming apparatus has been proposed that uses a conductor instead of a photoreceptor as a base and eliminates the need for a surrounding charger. This device includes the steps of: charging a photosensitive toner to a predetermined polarity and applying it onto a substrate; A step of exposing a light image to the toner to form an electrostatic latent image: While the toner in the area irradiated with light maintains conductivity, the toner area on which the electrostatic latent image has been formed is transferred to the transfer sheet. Applying a bias voltage of the same polarity as the initial charge polarity of the toner to the cough transfer sheet facing the toner to reverse the polarity of the toner that maintains conductivity, and at the same time transferring the toner to the transfer sheet. The image forming apparatus is configured to form an image on the transfer sheet by the following steps.

Incidentally, the toner remaining on the substrate without being transferred to the transfer sheet is scraped off by a cleaning member, but in this case, the scraped toner is stored in the toner container in order to effectively utilize the toner. It is usually collected. More specifically, the toner is configured to be collected in a hopper that supplies toner to a toner container.

However, some of the toner that has been scraped off has become conductive due to exposure to light. Generally, this type of photosensitive toner cannot be recovered quickly; it takes 8 hours to recover 100% (become insulating) and 20 minutes to recover 90%. Therefore, if the toner in the hopper is running low, the toner collected from the substrate will be immediately supplied into the toner container and used without being recovered. However, this means that a clearly degraded image is formed.

An object of the present invention is to provide an image forming apparatus that is designed to prevent such problems from occurring.

In order to achieve the above object, the image forming apparatus of the present invention has a photosensitive toner that becomes conductive when irradiated with light and then maintains conductivity for an appropriate period of time to a predetermined polarity. a step of charging the toner on the substrate; a step of exposing the toner on the substrate to a light image to form an electrostatic latent image;
While the toner in the light irradiated area remains conductive, the toner area on which the electrostatic latent image has been formed is placed facing the transfer sheet, and the toner is charged with the same polarity as the original charge polarity of the toner. This is a method of forming an image on a transfer sheet by applying a bias voltage to reverse the polarity of the toner that maintains conductivity and simultaneously transferring the toner to the transfer sheet. a toner container equipped with a sleeve for applying the toner thereon; a hopper for supplying the toner to the toner container; and a hopper for scraping off residual toner on the substrate after transferring the toner on the substrate to a transfer sheet. a cleaning member for collecting the toner in the image forming apparatus, a chamber for storing the collected toner scraped off from the substrate by the cleaning member; and a replenishment roller for supplying the collected toner in the room to a downstream in the hopper. The toner level sensor detects the amount of toner in the hopper, and the control means stops the replenishment roller when the amount of toner in the hopper is less than a predetermined value.

In this case, the control means may also operate a toner empty display means when the amount of toner in the hopper is less than a predetermined value.

According to this configuration, when there is sufficient toner in the hopper, the replenishment roller for collected toner can operate and the toner is supplied into the hopper as needed, but the toner in the hopper is When the amount decreases to below a predetermined value, the collected toner replenishment roller is forcibly stopped, and the collected toner is not fed into the hopper, and therefore, in this case, the reuse of the collected toner is also stopped. Therefore, the toner that has just been recovered from the substrate is not used for image formation while remaining conductive.

Certain JL Example - Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment in which the present invention is applied to a printer using photosensitive toner 1. As shown in FIG. Photosensitive toner used here
The particles are formed by integrating a photoconductive agent such as zinc oxide, a dye sensitizer, and a pigment with a binder resin, and when oxygen is adsorbed on the surface, they become insulating, and when oxygen is released, they become conductive. becomes. The removal of oxygen is performed using, for example, semiconductor laser light, as will be described later. The dye sensitizer plays the role of bringing the sensitivity of the toner 1 into the infrared light region (semiconductor laser light).

In FIG. 1, photosensitive toner 1 is contained in toner container #2 together with a magnetic carrier.

A sleeve 4 facing a conductive rotating drum 3 is provided within the toner container 2 . This sleeve 4 is adapted to be rotated in the direction shown by arrow A. On the other hand, the drum 3 facing the sleeve 4 is rotated in the direction shown by arrow B, and their opposing peripheral surfaces move in the same direction. Sleeve 4 is negatively biased while drum 3 is held at ground potential.

5 is an exposure device that exposes an optical image using a semiconductor laser. 6 is a transfer roller, which is negatively biased by a DC power source 7. A cleaning blade 9 serves to scrape off residual toner on the drum 3 that is not transferred to the transfer sheet 8.

A hopper 10 receives new toner from a toner bottle 11 and also receives collected toner from a chamber 12 dedicated to collected toner. The toner scraped off from the drum 3 by the cleaning blade 9 is temporarily transferred to the chamber 12.
After that, it is supplied to the downstream side of the popper 10 by the operation of the replenishment roller 13. 14 is a toner supply roller for supplying toner to the toner container 2 side. A toner level sensor 15 is installed in the hopper 10 to detect the amount of toner within the hopper 10. As this toner level sensor 15, for example, a piezoelectric tuning fork resonator can be used.

This piezoelectric tuning fork resonator is used as a vibrating part of the oscillation circuit, and when there is enough toner in the hopper 10, a load is applied to the vibrating part and the oscillation output becomes O, and the hopper 10
When the amount of toner inside decreases and no load is applied to the vibrating section, an oscillating output is generated.

In this way, toner level detection is performed.

The output of the toner level sensor 15 is processed by the control section 20. When the output of the toner level sensor 15 is below a predetermined value, the control section 20 controls the replenishment roller 13 to be inactive and to turn on the toner empty display means 17. The control unit 20 can be configured using, for example, a microcomputer.

Next, the operation of the apparatus shown in FIG. 1 will be explained. First, a negative bias voltage having the same polarity as the polarity (unipolarity in this embodiment) with which the photosensitive toner 1 is triboelectrically charged is applied to the sleeve 4 . On the other hand, the drum 3 is grounded. A magnet 16 is fixedly disposed within the sleeve 4 at a position facing the drum 3 with the sleeve 4 in between. The photosensitive toner 1 contained in the toner container 2 is mixed with a magnetic carrier by the rotation of the stirring roller 18 and triboelectrically charged to a negative polarity. The triboelectrically charged photosensitive toner 1 is conveyed on a rotating sleeve 4 and transferred to a drum 3 by a magnet 16.
A magnetic brush 19 is formed at a position opposite to. and,
When the magnetic brush 19 comes into sliding contact with the drum 3, the negatively charged photosensitive toner 1 is sequentially deposited over the entire length of the drum surface.

In this way, the layer of toner 1 formed on the drum 3 is conveyed to the exposure position by the exposure device 5 as the drum 3 rotates. At the exposure position, the toner layer on the drum 3 is exposed to a light image, irradiated with semiconductor laser light, and the toner whose electrical resistance decreases and becomes conductive passes through the grounded drum 3, where its charge is reduced. (This toner is represented by a white circle 1a in FIG. 1). On the other hand, the charged toner 1 that is not irradiated with light does not become conductive and maintains a negatively charged state. As a result, an electrostatic latent image is formed on the photosensitive toner layer on the drum 3 that has passed through the exposure position of the exposure device 5 based on the amount of negative charge held.

The toner layer on which the electrostatic latent image has been formed after passing through the exposure position by the exposure device 5 is conveyed to an area facing the transfer roller 6 as the drum 3 rotates. A negative voltage having the same polarity as the charged polarity of the photosensitive toner is applied to the transfer roller 6 by a DC power source 7, and the transfer sheet 8 is conveyed between the transfer roller 6 and the drum 3. The photosensitive toner 1a, which has lost its charge on the drum 3, maintains conductivity with its electrical resistance value decreasing until it reaches the area facing the transfer roller 6. Then, the transfer sheet 8 is conveyed between the transfer roller 6 and the drum 3 at the timing when the toner layer on the drum 3 reaches the area facing the transfer roller 6.

At this time, the transfer sheet 8 and the toner layer on the drum 3 are brought into contact with each other while a negative bias voltage is applied to the transfer roller 6.

As a result, ten charges of opposite polarity are injected from the drum 3 into the low-charge negative polarity toner 1a which has been made conductive by being irradiated with light. As a result, the toner 1a on the drum 3 irradiated with the laser beam becomes depolarized and is transferred to the transfer sheet. The negatively charged toner 1 on the drum 3 that is not irradiated with the laser beam is not in a conductive state and therefore maintains its negative polarity and is not transferred onto the transfer sheet 8 .

Note that some of the toner 1a that has become conductive after being exposed to light remains on the drum 3 without being transferred to the transfer sheet 8. Therefore, among the toner scraped off by the cleaning blade 9 and collected in the chamber 12 of the potper 10, this conductive toner 1a is also present.
Although it cannot be reused as it is, it is once stored in the chamber 12 and supplied to the downstream side of the hopper 10, and while it is stored in the hopper 10 for a long time, it adsorbs oxygen and returns to its initial state (insulated state). to recover. In this case, if the collected toner in the chamber 12 is supplied to the downstream side of the hopper 10 when the amount of toner in the hopper 10 is low, the collected toner will not be recovered sufficiently. However, in this embodiment, the toner level sensor 15 monitors the amount of toner in the hopper 10, and when the amount of toner falls below a predetermined value, the control section 20 operates to stop the replenishment roller 13. Since the state is forcibly stopped, problems such as the collected toner in the chamber 12 being given to the toner container 2 side through the hopper 10 and being reused without being restored to the initial state can be avoided. . When the control section 16 disables the replenishment roller 13, the control section 16 simultaneously turns on the toner empty display means 17.
Since the toner empty display unit is turned on by driving the
1, new toner can be supplied into the hopper 10. When a sufficient amount of new toner is supplied to the hopper 10, the toner level sensor 15 stops oscillating, and the controller 20 then controls the replenishment roller 1.
3, and the toner empty display means 1.
Turn 7 off.

As explained above, according to the present invention, when there is sufficient toner in the hopper, the collected toner replenishment roller can operate, and the toner is supplied into the hopper as necessary. When the amount of toner in the hopper becomes low and falls below a predetermined value,
The replenishment roller for collected toner is forcibly stopped,
The collected toner is not fed into the hopper, and reuse of the collected toner is also stopped. Therefore, the toner that has just been recovered from the substrate is not used for image formation while remaining conductive, and there is an effect that images of stable quality can always be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a main part of an image forming apparatus embodying the present invention, and FIG. 2 is a block diagram of a part thereof. 1... Photosensitive toner 2... Toner container, 3...
...Drum, 4...Sleeve, 5...Exposure device, 6...Transfer roller, 8...Transfer sheet, 9...Cleaning blade, 10...Popper 11...Toner bottle,
12...Room, 13...Replenishment roller, 1
4... Toner supply roller, 15... Toner level sensor, 17... Toner empty display means, 18... Stirring roller.

Claims (2)

[Claims] (1) A step of charging a photosensitive toner to a predetermined polarity and applying it onto a substrate, which becomes conductive when irradiated with light and then maintains conductivity for an appropriate period of time; The process of exposing a light image to the upper toner to form an electrostatic latent image; Transferring the toner area on which the electrostatic latent image was formed while the toner in the area irradiated with light maintains conductivity. Applying a bias voltage of the same polarity as the initial charged polarity of the toner to the transfer sheet facing the sheet to reverse the polarity of the toner that maintains conductivity and at the same time transfer the toner to the transfer sheet. A method for forming an image on a transfer sheet by a step of forming an image on a transfer sheet, the method comprising: a toner container including a sleeve for applying the toner onto the substrate; a hopper for supplying the toner to the toner container; In an image forming apparatus, the image forming apparatus includes a cleaning member for scraping off the residual toner on the substrate and collecting it in the hopper after the toner on the substrate is transferred to the transfer sheet. a chamber for storing toner; a replenishment roller for supplying collected toner in the room downstream within the hopper; a toner level sensor for detecting the amount of toner in the hopper; an image forming apparatus comprising: a control means for bringing the replenishment roller into a stopped state when (2) The image forming apparatus according to claim 1, wherein the control means operates a toner empty display means when the amount of toner in the hopper is less than a predetermined value.