JPS6018065B2 - developing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developing device for developing a member carrying a static latent image, and more specifically, the present invention relates to a developing device for developing a member carrying a static latent image. This relates to a developing device.

2. Description of the Related Art It has been widely known to develop a melted image formed by electrophotography or electrostatic recording using a developer containing a mixture of carrier and toner. The magnetic brush development method, which is one of these development methods, uses magnetic iron powder as a carrier, fine particles made of a chargeable colored resin as a toner, and a mixture of the two as a developer. There is. A carrier portion of these developers adheres to a magnet to form a magnetic brush, and the toner portion attached to the carrier is rubbed onto the static latent image, thereby causing the toner to adhere to the latent image and perform development. . As described above, toner in the developer is consumed each time development is repeated, and its ratio to carrier decreases, resulting in a decrease in the density of the developed image. In order to prevent this decrease in density, it is necessary to appropriately supply the same amount of toner to the developer as the amount of consumed toner. By the way, as a toner supply means that has been generally used, there is a fixed quantity supply method in which a prescribed amount of toner is supplied each time one developing operation or one sheet of latent image carrier is developed.

However, this quantitative supply method has the disadvantage that the developer concentration is extremely unstable because toner is supplied regardless of the amount of toner consumed. There is a method that improves this drawback by detecting developer concentration and supplying toner according to the detected value. Specifically, the ratio of carrier to toner in the developer being used is detected by optical or electrical means,
activating the toner supply means in accordance with the detection signal;
This is a method of keeping the developer concentration constant. However, among the above-mentioned detection means, photoelectric ones have the problem that the light source and light-receiving element are contaminated with developer material and tend to malfunction. It was complicated and expensive. An object of the present invention is to eliminate the drawbacks of the conventional developer concentration adjustment method as described above, to provide a developing device that can maintain an appropriate developer concentration, and further to prevent carrier deterioration. It is an object of the present invention to provide a developing device capable of maintaining the developing device in an optimal state for a long period of time without causing any problems.

The developing device of the present invention that achieves the above object includes means for applying a developer containing a mixture of toner and carrier to an electrostatic latent image carrier, a container for storing the developer to be used for development, and a container for storing the developer. a developer supplying means for supplying a predetermined amount of developer or a predetermined amount of carrier to the container; a means for discharging the developer in the developer storage container from the developer storage container in a predetermined amount at a time; The apparatus includes means for detecting the volume, and means for discharging toner into the developer storage container until the developer reaches a predetermined volume based on a detection signal from the volume detection means.

That is, in the present invention, a predetermined amount of developer or carrier is supplied into a developer container containing a predetermined amount of developer in advance, and on the other hand, approximately the same amount of developer as this supply is discharged from the container. Toner is supplied by detecting the amount of toner consumed by a volume detection means. As a result, the developer concentration in the developer storage container is always constant, and since a part of the carrier is constantly replaced, carrier deterioration does not occur, and the designated function can be performed for a long time without having to replace the carrier. be able to. It should be noted that conventionally known powder developer supply means and other general powder conveyance means can be used as the supply means and discharge means for each of the above-mentioned developers. In addition, the volume detection means is a combination of a powder float and a microswitch.
Detection of the upper surface of the developer by various means such as ultrasonic waves or a light receiving element, or detection of the upper surface of the developer by magnetic permeability, especially when the developer uses magnetic toner or magnetic carrier, can be applied. Incidentally, among the above-mentioned methods, the method using magnetic permeability is effective because it is easy to prevent malfunctions due to developer contamination of the detection means. The present invention will be described in more detail below with reference to Examples and explanatory drawings thereof. Note that in the embodiment, a recording apparatus to which electrophotography is applied is used as an image forming apparatus. FIG. 1 is a schematic side view showing the outline of the recording apparatus. In the figure, 1 is a drum-shaped photoreceptor having a conductive substrate and a photoconductive layer on the surface. The photoreceptor 1 forms a latent image by the Carlson method. Body 1 is
Rotate in the direction of the arrow.

Reference numeral 2 denotes a charger, and 3 an exposure means which converts light into an image based on a signal from a control means (not shown) and exposes the photoreceptor 1 with the light.

4 is a developing device according to the present invention; 5 is a transfer charger for transferring a toner image onto a transfer material; and 6 is a cleaning means for removing residual toner on the photoreceptor 1.

In the above configuration, the photoreceptor 1 on which a latent image has been formed is developed by a developing device, the developed image is transferred onto a transfer material by a charger 5, and further cleaned by a cleaning device to prepare for the next recording step. Figure 2 is arrow A in Figure 1.
This is an expanded view of the developing device 4 of the present invention as seen from the direction of FIG.

In the figure, 7 is a developer storage container containing a certain amount of developer having a predetermined toner and carrier ratio, 8 is a fly body member disposed inside the container 7, and the member 8 is connected to two screws. A right-handed screw and a left-handed screw are arranged in parallel and opposite each other, and the developer is circulated within the container 7 by the rotation of these screws. The container 7 has new developer and toner supply ports 7a and 7b above one end of these Hazazukabemura 8, and a feed screw 8b that discharges a fixed amount of developer at the bottom of the other end for development. There is an opening 7c for guiding the agent. Note that 16 in the figure indicates a container that accommodates the developer sent by the feeding screw. In FIG. 2, a mechanism having a magnetic body and a rotating non-magnetic body is used as a means for applying toner to the photoreceptor 1, but this mechanism is omitted here. The volume of the developer in the container 7 is detected by a volume sensing means 9 fixed to the wall of the container 7 based on magnetic permeability, and a detection signal from the means 9 operates the toner supply means. This toner supply means includes a container 11 that stores the toner 10 for supply.
The grooved roller 12 provided at the lower part of the toner is rotated, and as the roller 12 rotates, the toner falls onto the flywheel member 8 through the joint opening 7b. A container 13 adjacent to the toner container 11 is a storage container for a new developer 14, and the developer in the container 13 is delivered in fixed amounts by the rotation of a screw 15 at the bottom of the container 13, and is fed through the supply port 7a. It falls onto the above-mentioned Azusa member 8. The main components of the developing device 4 of the present invention have been described above. Next, the operation of the device 4 will be explained.
The developing device of the embodiment operates in synchronization with the operation of the photoreceptor 1,
The developer is circulated within the container by the rotation of the lamp member 8, and the new developer 14 falling from the groove opening 7a is mixed with the developer in the container 7 in fixed amounts.

Incidentally, the developer is normally contained in the container 7 up to the volume detection means position, but when the toner in the developer is consumed by the port image on the photoreceptor 1 during development, the volume of the developer increases depending on the amount of toner consumed. , resulting in a lower developer level. This level drop is detected by the volume detection means 9, and a signal sent from the means 9 causes the roller 12 attached to the container 11 of the toner 10 to be rotated, thereby discharging the toner. The toner supplied in this manner is mixed with the developer which is constantly supplied in a fixed amount, and reaches the container 7. When the amount of developer in the container 7 reaches a predetermined volume, the supply of the toner is stopped. Note that at the same time as the new developer is supplied, the same amount of the used developer is discharged out of the container 7 by the screw 8b, so the amount of developer in the container 7 does not change, and the volume detection means The developer concentration can be automatically adjusted using only the toner supply means 9 and the toner supply means. As described above, this embodiment automatically adjusts the volume detecting means and mainly the developer concentration, and does not have an optical means that causes problems such as toner contamination as in the past, so the density adjusting device can be extremely simplified. Can be adjusted accurately. Further, in the developing device of the present invention, since the developer in use is always replaced by a fixed amount, the developer capacity does not decrease due to the use of the developer, and it is possible to always develop a latent image in a stable state. In this apparatus, even if an error occurs between the amount of developer supplied and the amount of developer discharged, the developer concentration will never change.

For example, if the amount of discharge from the feed screw 8b' is slightly larger than the amount of supply from the feed screw 15,
The amount of developer in the storage container 7 decreases, and an amount of toner 10 is replenished accordingly. As a result, the developer concentration temporarily increases, the toner ratio in the discharged developer increases, and the
iA ratio decreases. Even though the amount of feed by the screw 8b is large, the amount of carrier discharged decreases, and ultimately the amount of carrier in the developer supplied by the screw 15 and the amount of carrier discharged by the screw 8b decrease. It becomes stable when it takes a constant value.In the above embodiment device, the developer with a toner weight ratio of 15% is
When developing using 0cc, 0.02cc of developer 14 with a toner weight ratio of 15% is supplied per copying operation of one sheet of transfer material, whereas if the developer is discharged during use at 0.02cc/sheet, 10 Even after 10,000 sheets were used, the developer concentration in the storage container 7 maintained a toner weight ratio of about 15%, and no deterioration of the carrier was observed at all.

Furthermore, while the supply of the developer 14 for feeding is 0.02cc/sheet, the amount of developer discharged during use is 0.018cc/sheet.
Even when the toner weight ratio of the developer in the container 7 was approximately 13%, the toner weight ratio was stabilized at about 13% even when the toner weight ratio of the developer in the container 7 was 10%. Note that this value of 13% is completely within the practical range. Incidentally, the practical range of the toner weight ratio in Examples was about 15±3%. By the way, as opposed to using a constant amount of developer as described above, it is also possible to adjust the developer concentration by changing the amount of developer discharged, and the experimental results will be explained with reference to Figure 3. .

In the apparatus shown in FIG. 2, the supply V of the supply V supply screw 15 is
The feed amount is set by the control means 17 so that 0.02 cc per sheet is supplied by the drive motor M2, and the discharge amount of the discharge screw 8b is set by the drive motor MI to be 0.02 cc per sheet.
Several values were set by the control means 17 around 022 ccl sheets. Figure 3 shows that when the volume of the developer to be discharged is greater than the carrier volume in the developer that is supplied at a constant rate, the toner weight ratio relative to the volume of discharge is stable at a constant value. . The amount of developer discharged per stack is 0.
．． 023cc, 0.022cc, 0.021cc, 0.
020cc, 0.019cc, 0.018cc, 0.0
When set to 17cc, the developer concentrations in the storage container 7 are 18%, 17%, 16%, 15%, 14%, and 13%, respectively.
%, the toner weight ratio was stable at 12%. Using the above results, depending on the needs and preferences of the operator of the copying machine, if the image density is too high, the ejection amount can be reduced, and if the density is too low, the ejection amount can be set to a large value. It becomes possible to obtain desirable development results. In the apparatus of the embodiment shown in FIG. 2, a mechanism for quantitatively exchanging developer using a screw is illustrated, but the same effect can be achieved using a bucket.

As for the developer, we have exemplified one that performs magnetic development using a mixture of magnetic carrier and toner, but other developers that include magnetic toner and non-magnetic carrier can be applied to volume detection means based on magnetic permeability. It is. When detecting volume without relying on magnetic permeability, a cascade development method using glass or resin beads can also be applied to the present invention. However, in the present invention, toner consumption can be further reduced by returning the toner collected by the cleaning means into the developer storage container. If some carrier is consumed during development, a small amount of carrier may be mixed into the supplied toner, or a separate carrier may be mixed. Although a fixed amount of developer is supplied in the above embodiment, it goes without saying that only carrier may be supplied. FIG. 4 is a front view showing another embodiment. In the figure, 18 is a developer storage container, 19 is a developer in use, 2 river volume detection means, 21 is a feed hawk member, the central part 21a performs the cassette action, and 21b, 21 at both ends.
c performs a feeding action. The central portion has a structure in which an elliptical plate is attached diagonally, and the two ends 21b and 21c are formed by screws. The above-mentioned feeding oak trunk member 21 has a motor 22
Rotates due to 23 is a developer for supply, which is stored in a container 24, and is conveyed into the container 18 by a screw 21b.

Further, a certain amount of the developer 19 in use is discharged into the container 25 by the rotation of the screw 21c. The developer 26 in the container 25 is moved into the toner storage container 30 through a conduit 29 by the suction force of a fan 28 on the outside of a wire mesh 27 which has an opening smaller than the diameter of the carrier and larger than the diameter of the toner. transported to. The toner in the container 30 is supplied by a supply means 32 operated by a signal from the volume detection means 20.
Mix until the predetermined volume is reached. By introducing the collected toner from the cleaning means into the container 30, it becomes possible to use the toner more effectively in the same way as described above. As described above in detail, the present invention enables a simple, inexpensive, and stable concentration control mechanism, unlike the conventional developer concentration control method using a developer concentration detection means.

In addition, the developer concentration control method and developer partial exchange mechanism not only keep the developer concentration constant, but also keep the developing ability constant, making it possible to produce stable images over a long period of time. . Note that the present invention is applicable not only to dry development but also to overflow development.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of a recording device to which the present invention is applied;
The figure is a schematic front view of one embodiment of the present invention, FIG. 3 is a graph showing the relationship between toner concentration and discharged developer volume, and FIG. 4 is a schematic front view of another embodiment of the present invention. be. In the figure, 1...photoreceptor, 4...developing device, 7...developer storage container, 8...rope rope member, 9...volume detection means , 10... Toner for joint use, 1 1... Container, 12... Grooved roller, 13... Container, 14... Developer, 15
...Screw, 16...Container, 17...
...Control unit, 27...Wire mesh, 28...
Fan, 29... Conduit. Tsui Diagram Polishing Diagram Z Diagram Grandchild Diagram 4

Claims (1)

[Scope of Claims] 1. A developing device for developing an electrostatic latent image, comprising means for applying a developer containing a mixture of toner and carrier to an electrostatic latent image carrier, and a developer for use in development. A container to store it in,
a supply means for supplying a fixed amount of new developer into the developer storage container; a discharging means for discharging the developer in the developer storage container in fixed amounts from the storage container; means for detecting the volume; means for supplying toner until the developer reaches a predetermined volume in the developer storage container according to the volume detecting means and the detection signal; and means for detecting the supply amount by the supply means and the discharge amount by the discharge means. A developing device comprising: a controlling means for controlling the developer concentration in the developer storage container. 2. The developing device according to claim 1, wherein magnetic permeability is utilized as means for detecting the volume of the developer in the developer storage container.