JP3522616B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a laser printer, a facsimile, and the like, and more particularly to an image forming apparatus for performing recycle development using an electrophotographic technique.

[0002]

2. Description of the Related Art An image forming apparatus for carrying out recycling development in a conventional technique will be described with reference to FIG. This has a generally used electrophotographic process, in which charges are applied to the surface of the photosensitive drum 1 by the main charging section 2,
The electrostatic latent image formed by exposing the image with the laser light of the laser optical system unit 3 is visualized by the toner charged to the same polarity as the potential of the surface of the photoconductor in the developing device 4, and the charged toner causes the electrostatic latent image to develop. The visible image is transferred onto the conveyed sheet by the transfer means 51. There is some untransferred toner on the surface of the photoconductor drum 1 on which the visible image is transferred,
This is scraped off by the blade 62 of the cleaning device 6, and light is emitted from the static elimination lamp 7 to return the surface potential to near 0 V and prepare for the next cycle again. On the other hand, the recycled toner collected by the cleaning device 6 passes through the recycled toner transport path 67 and is recycled to the developing device 4 again.
It is thrown into the toner hopper at the upper part of the sheet, mixed with the unused toner, and then thrown into the developing container again according to the toner replenishment signal.

[0003]

However, according to such a conventional method, if the recycled toner is large, the image is deteriorated, and the same T / D (toner weight / toner weight / toner weight / toner weight / toner weight / Despite the problem that the toner output value in terms of the percentage of the developer weight) was different, all the collected toner was re-charged into the developing container. This is because recycled toner is a toner that has been used once, so the charging performance is poorer than that of unused toner, the repulsive force between the developer particles is reduced, and the density of the developer is increased as a result, and the output of the Tonacon sensor is unused. This is because the value is higher than that of the same T / D developer containing only toner. For this reason, when the ratio of recycled toner increases in T / D detection using a normal magnetic permeability sensor, it is determined that T / D is lower than that of the same T / D of the normal developer, and problems such as overtoner occur. Had occurred. Therefore, as disclosed in Japanese Patent Application Laid-Open No. 8-286513 (which controls the amount of unused toner in accordance with the amount of recycled toner conveyed so as to keep the mixing ratio below a predetermined value), the recycled toner and the unused toner are not mixed. There is a description to control the mixing ratio. However, even if this technique is used, the amount of recycled toner due to repeated image formation is not stable, so the mixing ratio of the mixed toner generated is not a predetermined value or less, but is not stable, and the amount of recycled toner is large. In some cases, there is a concern that the mixed toner may be generated more than necessary.

[0004]

In order to solve the above-mentioned problems, the present invention provides, as a first invention, an image forming apparatus for carrying out recycle development in which toner collected by a cleaning device is resupplied to a developing container. An unused toner supply means for supplying unused toner to the developing container, a collection container for storing the toner collected by the cleaning device, a recycled toner detection means for detecting the amount of recycled toner in the collection container, and a recycling of the collection container Recycled toner replenishing means for replenishing toner to the developing container, toner concentration detecting means for detecting the ratio of carrier to toner in the developing container, and toner concentration controlling means for controlling the toner concentration based on the output value of the toner concentration detecting means. Depending on the outputs of the toner concentration control means and the recycled toner detection means, the unused toner supply And controlling the recycled toner feeding means, and a toner replenishment control means for controlling the ratio of toner to be replenished from each,

In the toner replenishment control means, the toner concentration control means outputs a toner replenishment signal, and the recycled toner detection means determines that the amount of recycled toner in the recovery container is within a predetermined range. When the recycled toner replenishing means and the recycled toner replenishing means perform a toner replenishment ratio at a predetermined value, when the recycle toner detecting means determines that there is a large amount of recycled toner in the collecting container, the unused toner replenishing means The ratio of toner replenishment between the toner replenishing means and the recycle toner replenishing means is controlled so that recycle toner is replenished more than the predetermined value, and the recycle toner detecting means determines that the recycle toner in the collecting container is low. Sometimes, the toner of the unused toner replenishing means and the toner of the recycled toner replenishing means To provide an image forming apparatus and controls so that recycled toner is supplied less than the ratio of supply said predetermined value.

As a second invention, the control content of the toner concentration control means is switched according to the mixing ratio of the recycled toner and the unused toner estimated based on the toner replenishment control means. An image forming apparatus according to the invention is provided.

[0007]

According to the first aspect of the present invention, the amount of recycled toner in the recovery container is detected, and the recycled toner replenishing means and the unused toner replenishing means can be operated separately. The mixing ratio of unused toner can be controlled.

According to the second invention, the mixing ratio of the recycled toner and the unused toner can be controlled by the first invention.
Since the optimum control content of the toner concentration control means according to the mixing ratio is prepared and switched in advance, an appropriate T / D can be maintained.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming unit of an image forming apparatus adopting an embodiment of the present invention will be described with reference to FIG. First, an electrostatic latent image formed by applying an electric charge to the surface of the photoconductor drum 1 by the main charging unit 2 and exposing by the laser light of the laser optical system unit 3
The image is visualized by the toner charged to the same polarity as the potential on the surface of the photoconductor in the developing device 4, and the visualized image by the charged toner is transferred by the transfer means 51 to the conveyed paper.
Part of the untransferred toner is present on the surface of the photoconductor drum 1 on which the visible image is transferred onto the sheet, and the blade 62 of the cleaning device 6 scrapes off the toner and irradiates the static elimination lamp 7 with light to cause the surface potential. Is returned to near 0 V and the next cycle is prepared again. When the unused toner is replenished, the unused toner is sufficiently stored in the toner hopper 49, and the unused toner replenishment motor 47 is rotated in response to the toner replenishment signal, whereby the sponge roller 48 is rotated and the developing container 4 is rotated.
Toner is replenished to 1. On the other hand, the recycled toner collected by the cleaning device 6 is temporarily stored in the collection container 68, and then is conveyed by the rotation of the recycled toner supply motor 65 and the rotation of the spiral 66 in the recycled toner conveyance path 67, and the development container 41. Be thrown into.

A method of collecting and supplying recycled toner will be described in more detail. A toner amount detection sensor 69 is attached to the collection container 68, and any device such as a photo sensor or a level sensor capable of knowing the amount of recycled toner in the collection container 68 with a certain degree of accuracy may be used. In this embodiment, two photo sensors (6
91, 692) and the two photo sensors 69
When neither 1 nor 692 detects toner, it is determined that the amount of recycled toner in the recovery container 68 is small, and when only the photo sensor 691 detects toner, the amount of recycled toner in the recovery container 68 is normal. When both the photo sensors 691 and 692 detect toner, it is determined that the amount of recycled toner in the collection container 68 is large. By increasing the number of photosensors, the amount of recycled toner in the collection container 68 can be detected more finely, and instead of the photosensors, a level sensor (by vibrating the sensor surface, how much of the surface the object contacts) It is also conceivable to use a sensor that outputs. The unused toner supplied to the developing container 41 is detected by detecting the amount of the recycled toner in the recovery container 68 by the above method and switching the rotation speed or the rotation time of the recycled toner supply motor 65 according to the result. And the ratio of recycled toner is changing. In the present embodiment, the amount of recycle toner to be replenished is determined when the recycle toner replenishment motor 65 is at the highest speed (or ON).
3 g / min at the maximum time ratio) and 1 g / min at the low speed (or at the minimum ON time ratio), and the unused toner replenishment rate is constant at 6 g / min. In addition, the mixing ratios of the toners supplied to the developing container 41 are 30% and 15%, respectively. Further, when it is made to correspond to the detection result of the toner amount detection sensor 69, it becomes as shown in Table 1 below.

[0011]

[Table 1]

It goes without saying that the control section is informed of the ratio of the unused toner to the recycled toner of the replenishment toner.

Next, a method of controlling the T / D of the developer in the developing device will be described. To measure the T / D of the developer in the developing device 4, the developing device is provided with a toner control sensor 46 (permeability sensor). This output value increases or decreases according to the amount of the magnetic substance in the developer. When the T / D is low, the ratio of the magnetic substance is high and thus the output value is high. Since the ratio is low, the output value is low. T
In the control for maintaining / D at a desired value, first, a predetermined T / D
The output value of the Tonacon sensor in the above is stored in a memory, and the output value of the Tonacon sensor at a desired T / D calculated based on this value and a data table prepared in advance is used as a threshold value. The output of the sensor is compared with this threshold value, and when the output value of the toner control sensor is higher, a toner replenishment signal is output, and in response thereto, the toner replenishment motor is rotated to replenish toner. This toner replenishment operation is continued until the output value of the toner control sensor falls below the threshold value. Similarly, when the T / D is desired to be increased, the threshold value is set low, and when the T / D is desired to be decreased, the threshold value is set high.

However, other factors also affect the output of the toner control sensor. For example, when the humidity rises, the charge amount of the toner in the developer decreases and the repulsive force between the developer particles decreases, resulting in the density of the developer. , And the output of the Tonacon sensor is higher than that of the developer having the same T / D at normal humidity. Also, as the developer ages, the carrier's ability to charge the toner decreases and the toner charge in the developer decreases. Similarly, the output of the Tonacon sensor is higher than that of the same T / D developer at normal humidity. Indicates. For this reason, in an actual machine, in order to reflect the above influence in the control for maintaining T / D, control is performed based on temperature, humidity, and developer counter data and control data prepared in advance. Since this correction is not related to the invention here, the other data will be omitted because it is data only at room temperature and normal humidity.

Further, in this embodiment, since the mixing ratio of the recycled toner and the unused toner can be detected and controlled, the toner control is performed according to the mixing ratio.

More specifically, the relationship between the mixing ratio of recycled toner and unused toner, T / D, and the output value of the toner control sensor is measured in advance, and control data is created based on this. In the present embodiment, as shown in FIG. 3, several T / D developers containing toner of each mixing ratio prepared in advance are prepared, and the control data is obtained based on the data obtained by plotting these. create. In the figure, the circles plot the output values of the Tonacon sensor for several types of T / D developers using only unused toner, and the same symbol indicates the development of several types of toner containing 15% recycled toner. □ is for several types of T / D developers of toner containing 30% recycled toner. This data and the T / D range of the actual use area (here T / D = 2.6 to 5.4%)
The control data is created from the data in. Usually, a curve is plotted, but in the actual use range, it may be approximated to a straight line. This control data may be table data or a function. The toner density control data for the three patterns A, B, and C in the figure are
When the pattern A replenishes only unused toner, the pattern B replenishes toner containing 15% recycled toner, and the pattern C replenishes toner containing 30% recycled toner. belongs to.

FIG. 4 shows a block diagram of the image forming apparatus adopting the present invention. As can be seen, in the T / D control in the developing device, the recycled toner supply motor 65 and the unused toner supply motor 47 are controlled according to the recycled toner amount detection sensor 69 in the collection container,
Further, the toner control data is changed based on the counter 84, the temperature sensor 85, and the humidity sensor 86.

[0018]

As described above, according to the first or second aspect of the present invention, the mixing ratio of the recycled toner of the replenished toner and the unused toner can be controlled, and overflow of the recovery container does not occur. Further, according to the third aspect of the present invention, since the toner concentration control data is switched according to the mixing ratio of the recycled toner of the supplied toner and the unused toner, accurate T / D control can be realized.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an image forming apparatus according to the related art.

FIG. 2 is a schematic view of an embodiment of the image forming apparatus according to the present invention.

FIG. 3 is a relationship diagram of T / D and toner controller sensor output when toner concentration control data according to the present invention is obtained.

FIG. 4 is a block diagram of the present invention.

[Explanation of symbols]

4; Developing device 41; Development container 46; Tonacon sensor 47; unused toner replenishment motor 6; Cleaning device 65; Motor for supplying recycled toner 67; Recycled toner transport path 68; Collection container 69; Recycled toner detecting means in collection container

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kotaro Kawasaki 1-2-2 Tamatsukuri Chuo-ku, Osaka-shi, Osaka Prefecture Mita Kogyo Co., Ltd. (72) Takashi Nagashima 1-2-2 Tamatsukuri, Chuo-ku, Osaka City, Osaka No. 28 within Mita Industry Co., Ltd. (56) Reference JP-A-6-110329 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/08 G03G 21/10

Claims (2)

(57) [Claims] 1. In an image forming apparatus for recycle development, in which toner collected by a cleaning device is resupplied to a developing container, an unused toner replenishing means for replenishing unused toner to the developing container, and toner collected by the cleaning device. A collection container for storing the recycle toner, a recycled toner detection means for detecting the amount of recycled toner in the collection container, a recycled toner replenishment means for replenishing the development container with the recycled toner in the collection container, and a carrier-toner ratio in the development container. Toner concentration detecting means for detecting, toner concentration controlling means for controlling toner concentration based on the output value of the toner concentration detecting means, and unused toner replenishing means according to outputs of the toner concentration controlling means and recycled toner detecting means. Controls the recycled toner supply means and controls the ratio of toner supplied from each. The toner replenishment control means outputs the toner replenishment signal from the toner concentration control means, and the recycle toner detection means determines that the recycle toner in the recovery container is predetermined. When it is determined that the amount is within the range, the toner replenishment ratio of the unused toner replenishing means and the recycle toner replenishing means is set to a predetermined value, and the recycle toner detecting means determines that there is a large amount of recycle toner in the collecting container. When judged, the ratio of toner replenishment between the unused toner replenishing means and the recycle toner replenishing means is controlled so that recycle toner is replenished more than the predetermined value, and the recycle toner detecting means controls the recycle toner detecting means in the collecting container. When it is determined that the amount of recycled toner is low, the unused toner replenishing means and the recycling Images forming apparatus you and controls so that the recycled toner is replenished less than the predetermined value the ratio of the toner supply toner replenishing means. 2. The control content of the toner concentration control means is switched according to the mixing ratio of the recycled toner and the unused toner estimated based on the toner replenishment control means. Image forming apparatus.