JPS62283368A - Toner concentration controller - Google Patents

Abstract

PURPOSE:To attain effective toner replenishing by replenishing toner basing on toner concentration detection information obtained from a standard plate image set of one time set at the head of an original group and adding the degree of original image when copying an original group of many sheets. CONSTITUTION:Toner concentration of a standard plate image is measured by a toner concentration detecting sensor 14 and converted to an electric signal and sent to a controlling section 15, and converted to the value of density of picture image by comparison with an electric signal that becomes a standard predetermined by correlation with the condition of charge of the standard plate latent image. When the density of the image indicates, for instance, a value of density D, if an original select switch 16 indicates a standard original, the controlling section 15 rotates the replenishing roller 12a of a toner replenishing device 12 connected to a developing device 11 at a replenishing rate of 1/3 to replenish toner to the developing device 11. on the other hand, when image density of D' is indicated, smaller toner replenishing rate is sufficient, toner replenishing is made for a time corresponding to 1/9 of time of copying operation.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a toner density control device used in an electrophotographic copying apparatus, and is used to optimize the density of a copied image and to chemotactic it. The present invention relates to a toner density control device.

[Conventional technology]

In a copying device that uses a two-component developer, the density of the copied image is greatly affected by the amount of toner in the developer held in the developer, so the image density must be maintained at an appropriate level. In order to maintain the toner, it is necessary to quickly replenish the toner in the developing device that has decreased due to consumption, and for this reason, a toner replenishing device is provided directly connected to the developing device.

The operation of this toner replenishing device is controlled by a toner 11 degree control device consisting of a sensor that detects a shortage of toner in the developing device and a control section that receives a signal from the sensor. The following four methods are used to detect the shortage of toner.

The - method detects a shortage of toner by directly measuring the ratio of toner components in the developer, and when the ratio of toner to carrier in the developer is lower than a specified value, the controller The toner replenishing device is started by the signal of In this method, image processing of patch images with standard density is performed prior to image processing of Haranawa, and if the result of measuring the density is lower than the specified density, toner replenishment is performed. It is meant to be started.

[Problem that the invention seeks to solve]

However, the former method keeps the toner concentration constant! Although ti can be controlled, it has the disadvantage that the density of the image does not necessarily become constant due to changes in the latent image formed on the photoreceptor.

Although the latter method has the advantage that the image density can be controlled to a constant level, it is necessary to form an image on the standard board before each original image, and therefore the llecir
A document feeder (such as an eluating document feeder (hereinafter referred to as "hole Di") that sequentially feeds a large number of documents to an exposure device for exposure and development) 1
It could not be applied to copying machines using

In other words, when using RDF, the document table and the exposure system on the side of the photocopying device 5 are fixed, and the document is continuously fed to the exposure section on the A side by the conveyor belt on the RDF side. On the other hand, in conventional copying machines that fixed originals and made copies, the electrostatic latent image of the standard plate image mentioned above is A standard plate with a constant density is pasted at a position close to the area where the original is placed9, and the standard plate is exposed in the same way as the original to expose the latent image of the standard plate on the photoreceptor. I was creating it.

Therefore, in a copying machine equipped with a DF, in order to create a latent image of a standard plate on a photoconductor, only the photoconductor is charged before the document is conveyed, and unnecessary parts are erased. It was erased with a lamp and an M image corresponding to the standard type plate was created.

In this method, the standard plate is created by charging the plate and turning on the charge eraser. During this process, it is necessary to turn off the exposure lamp, and multiple originals are transported one after the other. - When exposing, it is necessary to turn off the exposure lamp and turn it on again each time, which greatly reduces the image processing speed of the document and loses the advantage of using RDF.

As a result of solving this problem and improving it, the present invention provides a toner density control device that enables effective toner replenishment for detecting the density of standard board images without reducing the copying speed even when using a DF. It is intended for the purpose of providing.

[Pause: Child actor to solve the 4 points] The above purpose is to charge and charge a part of the image carrier before exposing the first sheet in a copying machine that continuously conveys and copies a large number of originals. This is achieved by a toner density control device characterized in that a toner image is created by applying a toner image, and the amount of toner replenishment during a subsequent series of copying operations is determined according to the density of the created toner image.

(Example〕 An embodiment of the present invention is shown in FIGS. 1-3.

FIG. 1 shows the configuration of a copying machine equipped with a toner density control device of the present invention.

■ is placed on the top of the copying machine ■ L D l'', and the original 2 placed on the original plate is moved by the original feed roller 3
The documents are conveyed from the lowest surface to the document table 5 on the upper surface of the copying apparatus by the conveyor belt 4K, which is circulated by the rotation of the conveyor belt 4K.

An exposure lamp 6 of an exposure type is fixedly placed on the document table 5.
Although a slit-shaped exposure section is configured to allow continuous projection, the circumferential surface of the photosensitive drum 8 is preliminarily exposed to the band 1! Since the electric charge is applied by the body 9 and the electric charge is erased in the non-image area by the charge erasing lamp 10, an electrostatic latent image of only the original image is formed, which is sequentially converted into a toner image in the developing device 11, and then transferred to the transfer pole. 13, the image is transferred to recording paper.

Further, a sensor 1 for detecting toner concentration is arranged on the circumferential surface of the photoconductor drum 8 in the downstream direction of the transfer pole 13, and measures the toner concentration of a designated standard beam plate portion of the circumferential surface of the photoconductor drum 8. Information is input to the control section.

An optical detection sensor using an LED as a light emitter and a phototransistor as a light receiver is suitable for detecting the toner concentration, but it is also possible to electrically detect the toner concentration using a surface electrometer.

In addition, the electric control unit 15 is fed back with the fourth level of charging by the charging electrode 9 as a factor regarding the toner concentration on the circumferential surface of the photoreceptor drum 8 mentioned above, and is further configured to be manually operated from outside the apparatus. The document select switch 16 is configured to input information regarding the density of both sides of the document 2.

The document select switch 16 selects three levels depending on the screen density over the entire area of the document 2, for example, a high-density document such as a catalog document that consumes a lot of toner, a standard document, and a light document that consumes little toner such as a pencil document. Depending on the signal, one of the three step-like programs shown in FIG. The toner replenishment ratio is determined based on the information.Next, toner concentration control in the copying apparatus will be explained with reference to FIGS. 2 and 3. In addition, in FIG. 2, the delay relationship due to the relative positions of means, sensors, etc. provided on the circumferential surface of the photosensitive drum is ignored.

When the copy button is pressed, the original on the original plate is detected, and when the original 2 is detected, the photosensitive drum etc. are rotated and the developing device 11 is activated.
The action is first started, and a standard plate latent image is formed on the circumferential surface of the photosensitive drum 8 by voltage application by the charging electrode 9 and partial lighting of the charge erasing lamp 100, and this is developed to create a standard plate image. do. The fourth charging condition for creating a standard plate latent image is set at a level suitable for determining toner density, and does not necessarily have to be the same as the charging condition during continuous copying. During this time, of course, no exposure/professional lighting will be performed.

Next, the toner density of the standard board image is measured by the toner density detection sensor 14, converted into an electrical signal, and sent to the control section 15, and the correlation with the charging condition of the standard board latent image described above is determined. It is converted into a value of image density by comparison with a predetermined standard electric signal.

'Of course, it is also possible to process the electrical signal value as it is.

As a result, when the image density shows the density value D shown in FIG. This rotationally drives a toner replenishing roller 12a of a toner replenishing device 12 connected to the developing device 11, thereby replenishing the developing device 11 with toner.

Therefore, depending on the signal from the control unit 15 upon completion of toner concentration measurement of the standard plate image, the copying operation is continuously performed by rotating the document feed roller 3 and lighting the exposure lamp 6. The toner replenishing roller 12a is rotated to replenish toner for a period of time corresponding to the notification, or in other words, for a period of time during which image processing is being performed on one of the three transported originals. There is.

On the other hand, if the image density measured by the toner density detection unit 14 is sufficiently high, for example at position D' in FIG. Toner replenishment will be performed for a corresponding period of time.

The above is a case where the original select switch 16 indicates a standard original, but the original select switch 1
Regarding the case where 6 indicates a light original, if the measured image density of the standard plate indicates position D,
As for the toner replenishment ratio, toner replenishment is performed for a time corresponding to 1/9 of the copying operation time. Further, when the measured image density of the standard plate is high indicating the position D', toner replenishment is not performed.

Although the embodiment described above deals with the case where the document select switch 16 is switched to three stages, the present invention is not limited to this number of stages. In this embodiment, an example has been described in which a program directly corresponding to the switched number of columns is stored in the control unit 15, but when continuous copying is performed for various recording paper sizes, the control unit 15 stores the program directly corresponding to the switched number of columns. A program determined by the combination of the number of rows and recording paper size is stored in advance, and one of the standard fishing boards measured as such is stored in advance. It is also possible to have the toner replenishment rate determined by the speed of the toner.

Furthermore, although the above described document selection switch 16 is set manually by the operator, it is not limited to this, but the document selection switch 16 is set manually by the operator.
Regarding [1], it is also possible to automatically detect the density of the original over the entire area of the original using a detection means provided near the exposure section, and to automatically switch to one of the plurality of stages of original selection based on this information. Chiru.

〔Effect of the invention〕

When copying a group of many originals, the present invention further utilizes the toner concentration detection information obtained from one standard board image set at the top of the original. By taking the degree of lightness into account, toner replenishment can be performed immediately in response to the original document, and as a result, even in copying machines using r(Dl), the detected density can be adjusted without sacrificing the image processing speed. On the other hand, toner density control trays have come into widespread use, allowing toner to be replenished in accordance with the toner consumption when copying a large number of sheets and to continuously obtain good copied images.

[Brief explanation of drawings]

FIG. 1 shows the toner 4-production G41 device of the present invention in an 11-m mechanical copying machine. ￥Complete drawing. FIG. 2 is a diagram of the operation of the above-mentioned equipment. No. 31 ri 1 is mentioned above! fill 1 bait 'J+H
Program (4, Rino 1st 9゜l 几I) 11
' 8 Photosensitive drum 9 Charged electrode 10 Charge erase lamp 11 ・Developer 12 Toner supply device 11 [Toner concentration detection sensor 15 --! fi control section

Claims (1)

[Claims] (1) In a copying device that continuously conveys and copies many originals, a toner image is created by charging and developing a part of the image carrier before exposing the first sheet. A toner density control device characterized in that the amount of toner replenishment during a subsequent series of copying operations is determined in accordance with the density of a toner image.