JPS61140965A - Electrophotographic recorder - Google Patents

Abstract

PURPOSE:To improve the consumption efficiency of a toner and to extend the life of a light source of an optical system by operating an electrostatic charge means in synchronization with the rotation of a photosensitive drum. CONSTITUTION:The photosensitive drum 1 under rotation at a constant speed is electrostatically charged to a positive polarity over the entire surface. An optical system 3 emits the light complying with the image in accordance with the input signal from the outside to expose the drum 1 after the drum 1 moves by L1 or above. The potential of the electric charge on the drum 1 decreases in the exposed part and an electrostatic latent image is formed. A developing device 4 starts functioning after the movement of the drum 1 by L2 or above and visualizes the latent image by the negative and positive reversal development of said image. More specifically, the drum 1 and the charger 2 operate synchronously and the developing device 4 starts operating after the movement of the drum 1 by the distance L2 or above. Both the drum 1 and the charger 2 stop operation. There is no sticking of the toner to the parts except the necessary developing parts. The consumption of the toner is thus decreased and the life is extended.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic recording apparatus for outputting and recording information of computers and the like.

2. Description of the Related Art Conventionally, in electrophotographic recording devices such as laser printers, it has been used to reduce wasteful toner consumption and to
Measures have been taken to prevent toner from adhering to areas other than the desired image area in order to prevent fatigue.

For example, the technique disclosed in Japanese Unexamined Patent Publication No. 56-95271 is one of them.

This technology is a device that obtains recorded images through positive development, in which toner is attached to the latent image area on the photoreceptor drum.
As shown in the figure, the photosensitive drum 1 is uniformly charged over the entire area by the charger 2, and the optical system 3 exposes the image area C other than the image area A and the non-image area 2 to charge the photoreceptor drum 1. It is configured to erase.

Problems to be Solved by the Invention However, in such a configuration, since the area of the non-image area is generally larger than that of the image area, the light emitting time of the optical system 3 becomes longer, which shortens the life of the light source. There was this problem. In addition, in positive-positive development, since the parts other than those exposed by the optical system 3 become images, recording kanji characters and fine line surfaces requires extremely high-precision light beam scanning, which increases costs. was there.

Therefore, the present invention provides a means for solving the above-mentioned problems, which reduces wasteful toner consumption through negative/positive reversal development in which toner is attached to a portion exposed with a light beam or the like to form an image. As a technical means of the present invention to solve the problem, when the photoreceptor drum is rotating, the charger is always kept in operation and until the charged part on the photoreceptor drum passes the development position. The action of this technical means is as follows.In other words, the rotational drive of the photoreceptor drum and the charger are synchronized in the operating state of the device, and the charged area is stopped for development. The development function is stopped until the device passes the development position, and only the image area is exposed to the light beam during negative/positive reversal development, which greatly improves toner consumption efficiency and reduces the need for optical systems. The light source also operates effectively and has a longer lifespan.

EXAMPLE An example of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, 1 is a photosensitive drum having a photoconductor such as amorphous silicon supported on the surface of Al, and 2
3 is a corona charger that uniformly charges the surface of the photoreceptor drum 10; 3 is an optical system such as an LED array that scans the surface of the photoreceptor drum 10 in the axial direction to form a latent image; 4;
6 is a transfer corona charger that electrostatically transfers the toner onto the transfer paper; 6 is a cleaning device that removes the toner remaining on the photoreceptor drum 1 after transfer; 7 is the transfer paper , 8 is a paper feeding device that feeds paper every fall, and 9 is a fixing device that heats and fixes the toner on the transfer paper.

Reference numeral 1o denotes a charge eliminating section that includes, for example, a long light source, for eliminating charges remaining on the photoreceptor drum 1.

The amount of rotational movement of the photosensitive drum 1 is detected by a detection means 11 such as a rotary encoder, and a control section 12 controls and drives the optical system 3, the developing device 4, the paper feeding device 8, and the like.

L is the distance from the charger 2 to the exposure position of the optical system 3,
L2 is the distance from the charger 2 to the developer 4.

The photosensitive drum 1 is rotated at a constant speed in the direction of the arrow in response to a start signal, and the amount of rotation is detected by a clock counter.

The entire surface of the photosensitive drum 1, which rotates at a constant speed, is uniformly charged to a positive polarity by a charger 2, as shown in FIG. 2A. After the photoreceptor drum 1 has moved by at least L1, the optical system 3 emits light in accordance with an image based on an input signal from the outside, and exposes the photoreceptor drum 1 to light. As shown in the opening of FIG. 2, the potential of the exposed portion of the photosensitive drum 1 decreases, and an electrostatic latent image is formed.

The developing device 4 starts its function after the photosensitive drum 1 has moved at least L2 or more, and develops the latent image in negative/positive inversion.
Visualize. That is, as shown in FIG. 2C, toner charged to the same polarity as the photoreceptor drum 1 is adhered to the portion where the charge has decreased due to exposure.

Next, the toner particles are transferred onto a transfer paper 7 by a transfer corona charger 6. In other words, the toner is separated from the photoreceptor drum 1 and transferred onto the transfer paper T by applying an electric charge of opposite polarity to the toner to the transfer corona charger 6 via the transfer paper 7 conveyed from the paper feed section. do.

The transfer paper 7 on which the toner has been transferred is sent to a fixing device 9.

It is heated and fixed.

After the transfer, the remaining toner on the photosensitive drum 1 is removed by a cleaning section 6 using a rubber blade or the like, and the entire surface is exposed to light in a charge eliminating section 1o to eliminate residual charges and return to its initial state.

When the latent image formation is completed by the optical system 3, the photosensitive drum 1 moves and stops at least until the end position of the latent image passes through the static eliminating section 10, and the charging section 2 and the developing device 4 also stop.

FIG. 3 shows the operation timing which is the main part of the present invention, in which a is the photosensitive drum 1, b is the charger 2, and C is the optical system 3.
, d indicate the operation of the developing device 4, with the upper side being in the operating state and the lower side being in the non-operating state. That is, at least the photoreceptor drum 1 and the charger 2 operate synchronously, and the developer 4 starts operating after the photoreceptor drum 1 has moved by a distance of L2 or more, and the developer 4 starts operating together with the photoreceptor drum 1 and the charger 2. Stop operation.

Further, a plurality of optical systems 3 for forming a latent image and a plurality of developing devices 4 for making the latent image visible are arranged alternately between the charger 2 and the transfer corona charger 6, thereby recording a plurality of colors. An example of this is shown in FIG.

Components having the same configuration and function as those in FIG. 1 are designated by the same numbers, and detailed explanation thereof will be omitted.

Reference numerals 14, 16, and 16 denote optical systems that expose the photoreceptor to light corresponding to a brass image of a desired color, for example, yellow, magenta, or cyan. Developing units 17, 18, and 19 have toners of colors corresponding to the optical systems 14, 16, and 16.

The entire surface of the photoreceptor drum 1 is uniformly and positively charged by the charger 2, and the first optical system 14 exposes the surface corresponding to, for example, a yellow image. Yellow toner is attached by positive reversal development. next,
A magenta optical system 16 exposes magenta to light, and a magenta developer 18 deposits magenta toner. Further, in the next cyan optical system 16, an image corresponding to the cyan image is exposed, and in the cyan developing device 19, cyan toner is adhered to the surface of the photoreceptor drum 1 to form yellow magenta.

Three color layers of cyan are formed.

The color image is electrostatically transferred all at once to a transfer paper 7 by a transfer corona charger 6, and then heated and fixed onto the transfer paper by a fixing device 9.

After the transfer, the remaining toner on the photosensitive drum 1 is removed by a cleaning section, and the residual charge is eliminated by a static eliminating section 1o.
Return to the initial state again.

FIG. 7 shows the operation timing of this embodiment.
is a photosensitive drum, b is a charger, C is a yellow optical system, d
indicates the operating state of the yellow developer, . is the magenta optical system, quantity is the magenta developer, q is the cyan optical system, and h is the cyan developer, with the upper side indicating the operating state and the lower side indicating the non-operating state.

L3 is from the charger 2 to the yellow optical system 14, L4 is from the charger 2 to the yellow developer 17, L5 is from the charger 2 to the magenta optical system 16, and L6 is from the charger 2 to the magenta developer 18.
, L7 indicates the distance from the charger 2 to the cyan optical system 16, L8 indicates the distance from the charger 2 to the cyan developing unit 19, and L9 indicates the distance from the cyan optical system 16 to the static eliminator 104.

Effects of the Invention The present invention synchronizes the operating timings of at least the photosensitive drum and the charger, and stops the function of each developer until the charged portion passes through the development position of each developer. Therefore, there is no toner adhesion to areas other than the required development area, and toner consumption is very effective. Furthermore, since the optical system emits light only in the necessary image area, it is possible to extend the life of the optical system.

[Brief explanation of drawings]

FIG. 1 is a principle diagram of an electrophotographic recording apparatus according to an embodiment of the present invention, FIG. 2 is a development process diagram of negative/positive reversal development according to the present invention, and FIG. 3 is an operation timing diagram for the configuration shown in FIG. FIG. 4 is a principle diagram of the main parts of a conventional electrophotographic recording device, FIG. 6 is a perspective view showing the exposure area on the photosensitive drum in the conventional device, and FIG. 6 is a color diagram in another embodiment of the present invention. A principle diagram of the electrophotographic sickle device, and FIG. 7 is an operation timing diagram for explaining the device of FIG. 6. DESCRIPTION OF SYMBOLS 1... Photosensitive drum, 2... Core charged body, 4... Reversal developing device, 6... Corona charger for transfer, 6.・・・−・Cleaning department, 7・
...Transfer paper, 8...Paper feeding device. Name of agent: Patent attorney Toshio Nakao and 1 other person
o, β (Kyu Lung Tokum 2-Corona Wei Pt) 艮高 1 Figure
4-・1 month and 5 months ago 5-# Kuzu on the copying roller η, Otsu・Cleaning 2' section Figure 3 Figure 4 Figure 6 Section 5 Figure 7

Claims (2)

[Claims] (1) A photoreceptor drum; a charging device that uniformly charges the surface of the photoreceptor drum; a latent image forming device that exposes the surface of the photoreceptor drum to form a desired latent image;
1. An electrophotographic recording apparatus comprising: a developing means for performing positive reversal development, and configured to operate the charging means in synchronization with the rotation of the photosensitive drum. (2) The electrophotographic recording apparatus according to claim 1, wherein the developing means is operated after the initial stop position of the photosensitive drum passes the developing position of the developing means.