JPH01244482A - Method for controlling replenishing quantity of toner - Google Patents

Abstract

PURPOSE:To improve the accuracy of the toner replenishing quantity to a developing device by controlling the toner replenishing quantity to the developing device in accordance with a prescribed area ratio. CONSTITUTION:When the detected outputs of an original size sensor 10 and original reading sensor 11 are supplied, a microcomputer 9 decides the picture area and area to be developed of an original and calculates the ratio between both areas. The toner replenishing quantity to a development counter by means of a toner replenishing means 8c is controlled in accordance with the calculated area ratio. Thus the accuracy of the toner replenishing quantity is improved and a uniform, stable, and high-quality picture is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for controlling the amount of toner replenishment in an electrophotographic apparatus.

(Prior Art) In an electrophotographic apparatus, as is well known, the density of the developer decreases in proportion to the number of copies. For this reason, a normal electrophotographic device creates a P sensor pattern on the photoreceptor in front of the original image every 10 times copying is performed, and detects when the density of the image of this P sensor pattern is low. The present invention includes a toner replenishing device that replenishes toner by turning on/off toner replenishment SQL every time copying is executed x times until the next ] to toner concentration detection time. As is clear here, with conventional toner replenishment devices, the amount of toner replenishment for −° times is always a constant amount (in most cases, the amount is sufficient to replenish the average amount of toner consumed during maximum size copying). The l/ner amount replenishment control is carried out so that the following is achieved.

On the other hand, electrophotographic apparatuses have been provided that have a so-called trimming function that can erase or extract an arbitrary area of a copy document and copy the image. The amount of toner consumed in this electrophotographic apparatus differs depending on whether the entire area of the copy original is copied or when the - portion of the copy original is trimmed and copied.

Therefore, in this electrophotographic apparatus, the conventional l.
When replenishing toner using the toner amount replenishment control method,
When copying a document that has been cropped, toner may be oversupplied, causing toner to settle on the white areas of the image and causing background smudges and toner scattering, making it difficult to copy properly. but? 41 There was a drawback that it became difficult to use.

This electrophotographic device having a rimming function is disclosed in Japanese Patent Application No. 61-144068 (Japanese Unexamined Patent Publication No. 62-2999818).
As described in the above publication, a toner replenishment amount control method has also been proposed in which the amount of toner replenishment to the developer is controlled according to the proportion of the copy area of the document to eliminate the above-mentioned drawbacks. .

However, the conventional I-ner replenishment amount control method described above,
Even though the increase or decrease in the image area of the document to be image scanned (presence or absence of trimming) is taken into consideration, the amount of I.
Na's g7f'! We are trying to replenish the consumed amount. For this reason, in the conventional 1 hener replenishment method, the image forming area of the original (the image area of the original formed on the photoreceptor) and the developing area (the latent part of the photoreceptor where 1 to 1 hener are deposited) area) Which ratio (hereinafter, this ratio will be referred to as screen area ratio)
Depending on the size of the toner, an excess or deficiency of toner may be supplied, resulting in problems such as toner scattering, background smudges on copies, and a decrease in copy density.

In other words, with conventional toner replenishment devices, new toner replenishment can keep up with the toner consumption even for originals with an image area ratio of 100%, such as a full black image on both edges of the original. , usually image area ratio 20% ~
It is necessary to set the amount of toner corresponding to 30% to be replenished sequentially.

Therefore, like a text manuscript, the image area ratio is 5% to 7%.
When the toner consumption is relatively small, the amount of toner supplied in the developer becomes excessive, causing problems such as toner scattering and background smearing on copies.

On the other hand, when copying an original with a high image area ratio and high I/ner consumption, such as a photographic original, the amount of l/ner consumed is greater than the amount of replenished I/ner. This causes a decrease in copy density.

(Objective) An object of the present invention is to provide a method for controlling the amount of I.ner replenishment that can improve I.ner replenishment accuracy and stability of image quality.

(Structure) The toner replenishment control method according to the present invention is characterized in that the amount of toner replenishment is controlled based on the ratio between the image forming area and the developing area of the document.

Embodiments of the present invention will be described in detail below with reference to the drawings.

For example, as shown in FIG. 1, the present invention is composed of an image forming area detecting means, a developed area detecting means, an image area ratio calculating means, and a l/ner replenishment amount setting means. The ratio between the image forming area detecting means and the developing area obtained by the developing area detecting means is calculated by the image area ratio calculating means, and based on the calculated image area ratio, the Set the toner supply amount.

Here, the image forming area detection means is a means for detecting the image area of the document formed on the photoreceptor, and is based on the output of, for example, a well-known document third sensor or a document reading sensor such as a digital copying machine. This method detects the total area of the copy area of the document.

The developed area detecting means is a means for detecting the area of the developed portion within the above-mentioned image forming area, that is, the area of the latent image portion where toner is deposited on the photoreceptor, for example, in digital copying. The number of dots corresponding to the image signal among the information (dots) read by the document reading sensor in the machine is counted, or based on the amount of light received by the sensor that receives the reflected light from the document in the optical document reading means. This is means for detecting the area to be developed of the original.

The image area ratio calculating means is a means for calculating the ratio between the above-mentioned image forming area and the developing area, and is constituted by, for example, a CPU of a microcomputer built in the copying machine.

The toner replenishment amount setting means is a means for setting a new toner replenishment amount based on the above-mentioned image area ratio. It is constituted by a timer that controls the operating time of the toner replenishment S01°.

The present invention is implemented in a digital copying machine as shown in FIG.

In the figure, a document reading device 1 scans a document 3 placed on a contact glass 2 and sends information (dots) obtained by subdividing the image of the document 3 to a writing device 1. The writing device 4 converts this original information into an optical image, projects the original optical image onto the photoreceptor 5-1-, and forms a latent image of the original on the photoreceptor 5.

As is well known, the latent image formed on the photoreceptor 5 is visualized with toner supplied from a developing device 6, and then transferred onto a transfer paper by a transfer device 7.

The developing device 6 is provided with an l/toner replenishing device 8 for replenishing new toner into the developer whose l/toner has been consumed by developing the latent image. This toner supply device 8
It is composed of a hopper 88 containing toner, and a toner replenishing roller 5oLsc that drives the toner replenishing roller 8b.

Here, the toner supply S01.8c is connected to an output terminal of a microcomputer 9 (control device) built into the copying machine, as shown in FIG.

The microcomputer 9 also includes an output from a document size sensor 10 for detecting the size of the document 3, and a document reading sensor I1. (CCU) output etc. are given.

The toner replenishing devices 1 to 8 configured as described above are driven as follows.

That is, in FIG. 2, the original 3 is sent to the cellar 1, and the copy area of this original 3 is determined (1-This copy area does not necessarily match the original size, such as rimming, reduction, enlargement, etc.) Later, the copy machine Copy Star 1~
When the switch is turned on, a latent image of the document 3 is formed on the photoreceptor 5- according to the image forming process described above. This latent image is developed with 1-toner supplied from the developing device 6, and then transferred onto the transfer paper.

On the other hand, in the above-mentioned copying machine, the l.ner replenishment signal is output every time a copying operation is completed or every time a predetermined number of copies are completed. Note that this 1 to toner replenishment signal may be outputted at the time when the density of the P sensor pattern image becomes thinner.

When the toner replenishment signal is output, a toner replenishment routine 1 to 1 consisting of a program as shown in FIG. - It is operated according to the program mentioned above.

When the toner replenishment routine 1 to 1 starts in FIG. 1, the image forming area S1 is first detected by the image forming area detecting means described above. This image (the image forming area S1 is the document reading sensor of the document reading device 1)
It is determined by the total number of tonts output by 1. Then,
The aforementioned developed area S2 is detected by the developed area detecting means. The developed area S2 is determined based on the number of dots in the developed area (image area of the original) output by the original reading sensor 11.

When the detection of the stiff image forming area S1 and the developing area S2 is completed, the image area ratio (S2151.) is calculated. This image area ratio is such that the number of dots in the image forming area S1 is (3X], 07) and the number of dots in the developed area S2 is (6
X10'), it becomes (0, 2).

Next, the amount of toner replenishment is set based on this image area ratio. Here, as is clear from FIG. 2, the amount of toner replenishment is proportional to the rotation time of the toner replenishment roller 8b, so as shown in FIG. One hener replenishment roller 8b required to replenish the replenishment amount, that is, the amount of toner consumed by development.
For example, when the image area ratio is (0, 2), the appropriate amount of toner can be replenished by rotating the toner replenishing roller 8b by (0,34 sec). I can do something. Furthermore, the fifth
The graph shown in the figure is determined experimentally in advance in accordance with the specifications of the I.na fetus 8, and its relational expression is stored in the ROM of the microcomputer 9 in advance.

Next, when the rotation time (1:o) of the toner replenishment roller 8b is set based on the above image area ratio, 1 to toner replenishment 5OL8c are turned on. As a result, the toner replenishing roller 8b starts rotating and toner replenishment is started. Next, the on time (1) of this toner supply Sol, 8c is 1
- When the rotation time of the toner replenishment roller 8b reaches the set value (LO), the toner replenishment 501.8c is turned off and the rotation of the toner replenishment roller 8b is stopped. As a result, the developer in the developing device 6 is replenished with new toner equal to the amount consumed by development. Then, in the next step, the presence or absence of the next copy start signal is determined,
If there is no start signal (if not continuous copying), the program returns to the main routine of the copying machine, and if there is a star 1 signal (if continuous copying), the above program is repeatedly executed. In addition, in the above program, 1
An example is shown in which the toner is replenished after each copy operation, but for example, the calculation results of the image area ratio for each copy are accumulated for a predetermined number of times, and 1 henna kite is executed for a predetermined number of times based on this cumulative value. It is also possible to replenish them all at once.

Thereby, the influence of the toner replenishment accuracy of the toner replenishing device 8 and the reading error of the document reading device 1 can be reduced.

In addition, in order to prevent the toner replenishment accuracy of the toner replenishment device 8 and the occurrence of excess or deficiency of L/toner replenishment due to reading errors of the document reading device 1, the P sensor pattern density formed on the photoreceptor S is set to a predetermined value. If any of the above occurs, 1 hener replenishment will be stopped regardless of block 11 above, and if the P sensor pattern density falls below the predetermined value, the P sensor pattern density will continue until the P sensor pattern density reaches the predetermined value. It is also possible to forcibly supply 1 henna in preference to the above program.

(Effects) As described above, according to the toner replenishment amount control method according to the present invention, it is possible to replenish toner in an amount corresponding to the surface area ratio of the original image, and to stabilize the 1 to 1 density and the copy image density. be able to.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a schematic diagram of a copying machine in which the present invention is implemented, FIG. 3 is a block diagram showing an example of a control device in the above embodiment, and FIG. are flowcharts 1 to 5 showing the operation program of the control device, and FIG. 5 is a diagram showing the relationship between the image area ratio and the rotation time of the toner replenishing roller in the above embodiment. 1... Original reading device, 3... Original, 4...
...Writing device, 5...Photoconductor, 6...Developing device, 8...Toner supply device, 8a...Hopper, 8b...Toner supply roller, 8c...・Toner supply SQL, 9...Microcomputer, 11
...Original reading sensor. Q η Stomach 吋 N et al ++-1S) (:) c>, S. \Q descendants

Claims (1)

[Claims] A method for controlling the amount of toner replenishment to a developing device that develops a latent image of an original image formed on a photoreceptor, the method comprising controlling the amount of toner replenishment based on the ratio of the image forming area of the original to the developed area. A toner replenishment amount control method.