JPS63234271A - Developing density controller - Google Patents

Abstract

PURPOSE:To reduce the size of an auxiliary light source and to permit exact correction of a quantity of light by detecting the electrostatic latent image potential formed by the auxiliary light source by a potential detecting means and correcting the quantity of light of the auxiliary light source to maintain the specified potential. CONSTITUTION:The electrostatic latent image corresponding to the image of an original 11 is formed by an exposing part 10 on a photosensitive body 1. On the other hand, the specified quantity of light is projected by the auxiliary light source 20 to the non-image part where the electrostatic latent image is not formed, by which a patch is formed. This light source 20 receives the supply of electric power for lighting from a means 22 for controlling the quantity of light. The potential of the electrostatic latent image is thus detected by the potential detecting means 21. The detection output is inputted to the means 22 for controlling the quantity of light when the latent image potential is detected. The means 22 compares the actual detection output and reference potential and corrects the quantity of light of the light source 20 so as to reduce the difference if there is such difference between the two values. The light source 20 and the means 231 can be made into the smaller constitution and the execution of the correction of the quantity of light with high accuracy is permitted if the light source 20 is controlled in such a manner.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a development density control device for adjusting the amount of toner to be supplied to a developing device for developing an electrostatic latent image.

``Prior Art'' In electrophotographic copiers and printers, a photoreceptor is exposed to light to form an electrostatic latent image, which is developed by a developer, and then toner is transferred to recording paper. .

It is well known that in such an apparatus, the developed density changes due to changes in the amount of toner contained in the developing device (the density may change even though the amount of toner is constant).

For this reason, various developer density control devices have been developed that predict the amount of toner consumed by the developing device and supply new toner to compensate for the consumed amount.

FIG. 2 is a schematic configuration diagram showing an example thereof.

A photosensitive drum 2 carrying a photosensitive member 1 on its outer peripheral surface is supported so as to rotate in the direction of arrow 3. This photosensitive drum 2
A charger 4, an auxiliary light source 5, a developing device 6, and a light reflection density sensor 7 are arranged around the outer periphery. The exposure section 10 is located between the charger 4 and the auxiliary light source 5. Further, the detection output of the light reflection density sensor 7 is input to the toner amount adjusting means 8. The toner amount adjusting means 8 is a device that accommodates a toner dispenser or the like that adjusts the amount of toner supplied to the developing device 6.

Here, first, when the photoreceptor 1 is uniformly charged by the charger 4, an image of the document (not shown) is exposed to light gB10, but at this point, an area (non-image) on the photoreceptor 1 that is not exposed to light is exposed. The auxiliary light source 5 irradiates a certain amount of light to the part) to eliminate static electricity.

The electrostatic latent image obtained in this way is called a patch, and is
It is used to detect the developed density. That is, this electrostatic latent image is developed by the developing device 6 together with the electrostatic latent image corresponding to the image of the document. A certain amount of toner adheres to the non-image area after development, and a light reflection density sensor 7 detects the light reflection density of that part.

If the photoreceptor l is always charged to a constant potential, the static electricity is removed using the auxiliary light source 5 with a constant amount of light, and development is performed under constant conditions, the light reflection density of the toner attached to the non-image area should be a constant value. .

However, when the amount of toner in the developing device 6 changes, this light reflection density also changes. Therefore, the toner amount adjusting means 8 recognizes the change in the light reflection density, converts this into a toner amount, and supplies the required amount of toner to the developing device 6.

"Problems to be Solved by the Invention" Now, in such a developer density control device, if the amount of light irradiated by the auxiliary light source 5 fluctuates, it becomes impossible to stably control the amount of toner supplied.

For example, when a light emitting diode or the like is used as the auxiliary light source 5, the amount of light may differ from the set value during the startup period from startup until the temperature stabilizes. Furthermore, changes in the light intensity of the light source over time and dirt due to long-term use cannot be ignored.

Therefore, conventional measures have been taken to stabilize the auxiliary light source as shown in FIG.

The auxiliary light source 5 includes a light emitting unit 52 in which several light emitting elements are arranged and fixed inside a cover 51, a light guide 53 made of a light guide member such as an acrylic plate, and a notch in the light guide 53. optical sensor 54 and power source 5
It consists of 5.

The auxiliary light source 5 guides light emitted from a light emitting section 52 onto the photoreceptor 1 through a light guide 53, and a portion of the light is received by an optical sensor 54 to detect the amount of light. The output of the sensor 54 is then compared with a certain reference value, and if a decrease in the amount of light is detected, corrections such as increasing the driving power supplied from the power source 55 are performed. When there are a plurality of light emitting elements, the number of light emitting elements may be increased or decreased.

Conventionally, such self-feedback has been used to stabilize the light amount of the auxiliary light source.

However, since such an auxiliary light source requires an optical sensor, a light guide, etc., it becomes large and causes an increase in cost. Further, if the surface of the light guide 53 facing the photoreceptor 1 and the surface facing the optical sensor 54 become different in dirt, an error will occur in the corrected light amount.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a development density control device that can reduce the size of an auxiliary light source and perform more accurate light amount correction.

"Means for Solving the Problems" The developing density control device of the present invention includes an auxiliary light source that irradiates light onto a non-image area of a uniformly charged photoreceptor, and a non-image area formed by removing static electricity by irradiating the light. a potential detection means for detecting the latent image potential of the latent image in the non-image area, a light amount control means for receiving the detection output of the potential detection means and comparing it with a reference potential, and correcting the light amount of the light source; A developing device that develops an electrostatic latent image, and a toner amount adjusting means that adjusts the amount of toner supplied to the developing device based on the light reflection density of the non-image area after the development. It is.

"Function" In the development density control device described above, the potential detection means detects the latent image potential of the electrostatic latent image formed by the auxiliary light source, and corrects the light amount of the auxiliary light source so that the latent image potential becomes constant. Therefore, the latent image potential is stabilized and the toner density after development faithfully depends on the toner amount in the developing device, so that the toner amount can be adjusted accurately.

Embodiment FIG. 1 is a schematic diagram showing an embodiment of the developer density control device of the present invention.

In the figure, a cleaning device 16, a static elimination lamp 17, a charger 1
8, auxiliary light source 20, potential detection means 21, developing device 6, light reflection density sensor 7, transfer device 23 and peeling corotron 24
and are arranged.

The detection output of the potential detection means 21 is connected to the light amount control means 22 so that the light amount of the auxiliary light source 20 is controlled thereby. Further, the detection output of the light reflection density sensor 7 is inputted to a toner amount adjusting means 8, which is wired so that the amount of toner supplied to the developing device 6 is adjusted.

In the apparatus having the above configuration, an image of a document 11 is first irradiated by an exposure lamp 12, and the reflected light is reflected by mirrors 13a and 1.
An image is formed on the photoreceptor 1 by the lens 14 and the right side of the 3b.

The photoreceptor 1 is cleaned twice by a cleaning device 16, unnecessary charges are removed by a static eliminating lamp 17, and then uniformly charged by a charger 18.

An electrostatic latent image corresponding to the image of the original document 11 is formed on the photoreceptor l in the exposure section 10 . This electrostatic latent image is developed by a developing device 6 and transferred onto a recording paper 30 by a transfer device 23. The recording paper 30 is peeled off from the photoreceptor 1 by a peeling corotron 24 and sent to a fixing device (not shown) by a conveyor belt 25.

On the other hand, on the photoreceptor 1, a non-image area where an electrostatic latent image corresponding to the image of the document is not formed is irradiated with a certain amount of light by the auxiliary light source 20 to form a patch. The auxiliary light source 20 is composed of a light emitting diode or the like, and receives power for lighting from a light amount control means 22. In this way, the latent image potential of the electrostatic latent image formed on the non-image area of the photoreceptor 1 is detected by the potential detection means 21.

This potential detection means 21 is a known device used to measure the potential of a latent image for the purpose of improving the quality of the recorded image. It operates to find the potential of a part.

When the latent image potential is detected in this way, the detection output is input to the light amount control means 22. If the amount of light from the auxiliary light source 20 is constant, this detection output should take a preset constant value. This constant value is used as a reference potential and compared with the actual detection output, and if there is a difference between the two, the light amount of the auxiliary light source 20 is corrected to reduce the difference.

In this way, the sight of the auxiliary light source 20 is controlled to always take a constant value.

Thereafter, when this electrostatic latent image is developed in the developing device 6, the light reflection density sensor 7 detects the light reflection density, and the toner amount adjusting means 8 uses the detected output to supply the toner to the developing device 6. Determine the required amount of toner. In this way, the amount of toner in the developing device 6 becomes constant, and the developer density can be stabilized.

"Modification" The developer density control device of the present invention is not limited to the above embodiments.

As the auxiliary light source, not only light emitting diodes but also various known light emitters such as fluorescent lamps may be used.

Further, the auxiliary light source 20 may be provided between the charger 18 and the exposure section 10.

Furthermore, as shown in Fig. 4, after forming an electrostatic latent image (patch) in the non-image area (steps ■, ■) and detecting the patch potential (step ■), the patch is immediately developed. (Step ■), which can be used to determine the development density. At this time, the patch potential and the reference potential are compared to determine the difference (steps ①, ②, ②), and the difference is added (or decreased) to the bias of the developing device by the bias control means ( Steps (■, ■): Change the developer bias only during patch development. In parallel, detect the patch density (step ■) and adjust the toner amount (steps ■, ■).
).

On the other hand, the difference between the patch potential and the reference potential is manually input to the light amount control means through the bias control means (steps ■, ■,
, ■), or a method of correcting the light amount of the auxiliary light source in the next cycle (step 0, ■) may be used. This method is suitable for high-speed copy processing.

"Effects of the Invention" According to the development density control device of the present invention described above, the latent image potential of the electrostatic latent image formed on the photoreceptor is directly measured and stabilized using the auxiliary light source, so it is highly accurate. The development density can be controlled by Further, if the auxiliary light source is controlled as described above, the auxiliary light source and the potential detection means can be made relatively compact, and the device can be easily miniaturized.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the developer density control device of the present invention, FIG. 2 is a schematic configuration diagram showing an example of a conventional developer density control device, and FIG. 3 is a cross-sectional view of the auxiliary light source. FIG. 4 is a processing flowchart of a modification of the developer density control device of the present invention. DESCRIPTION OF SYMBOLS 1...Photoreceptor, 6...Developer, 7...Light reflection density sensor, 8...Toner amount adjustment means, 20... - Auxiliary light source, 21... Potential detection means, 22... Light amount control means. Applicant: Fuji Xerox Co., Ltd. Agent

Claims (1)

[Claims] an auxiliary light source that irradiates light onto a uniformly charged non-image area of a photoreceptor; and a potential detection means that detects a latent image potential of a latent image in the non-image area formed by removing static electricity by irradiating the light. ,
a light amount control means for receiving the detection output of the potential detection means and comparing it with a reference potential to correct the light amount of the light source; a developing device for developing the electrostatic latent image; A developer density control device comprising: toner amount adjusting means for adjusting the amount of toner supplied to the developing device based on the reflection density.