JPS604189Y2 - developing device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a developing device used in an electrostatic recording device including an electrophotographic device, and in particular, a toner density control device with a dust collection member for a two-component developer using a magnetic carrier. The invention relates to a developing device having the following.

Conventional two-component developers include a developer used in a magnetic brush development device, which is made up of a magnetic carrier such as iron powder, and toner, and a developer used in a cascade development device, which is made up of a glass bead carrier and toner, for example. In terms of the form and function of the device, magnetic brush developing devices are more widely used than cascade developing devices because they are simpler and have superior image quality.

The developer used in the device according to the present invention is one of the two developers mentioned above, which is composed of a magnetic carrier and a toner.

Generally, in order to obtain high-quality images with an electrostatic recording device, it is necessary to keep the mixing ratio of the two components as constant as possible, and therefore there is a means to automatically control the mixing ratio. It is well known that the developing device is provided in conjunction with the developing device.

As a method for keeping the mixing ratio of the developer constant, there have been other methods such as measuring the resistance of the developer and measuring inductance. In comparison, it had the characteristics of a faster response, higher accuracy, and less influence by humidity and other factors.

However, when a new copy is started, the measurement accuracy is good, but as the number of copies increases, dust, especially fibrous dust, mixed in the developer adheres to and accumulates on the coil whose inductance is to be measured. The result was that the developer flow was disturbed.

As a result, the inductance corresponding to the magnetic permeability of the developer cannot be accurately measured, resulting in the problem that the actual toner concentration is erroneously judged as if it had a higher concentration.

For example, as the number of copies increases, the actual toner density gradually decreases compared to the initial set value of the toner density, until the developed visible image has a significant decrease in density.

The present invention provides a developing device having a toner density control device that measures the inductance of a coil, in which dust is prevented from adhering to and accumulating on the inductance measuring coil, so that a stable toner density is always maintained, and therefore stable images can be obtained. The object of the present invention is to provide a developing device that can move around the image.

The purpose is to provide a developer container for storing a developer, a sleeve disposed within the container to cause the developer to flow along its surface, a scraper to scrape off the developer on the surface of the sleeve, and a scraper for scraping off the developer from the surface of the sleeve. In a developing device having a coil roller for measuring inductance for controlling the toner concentration of the developer in the path, a position in the path of the flowing developer near the coil and, if necessary, other than the vicinity of the coil. A distant relative can be achieved by using a developing device equipped with a member for collecting dust in the developer.

Originally, toner concentration control devices using an inductance measurement method include a method in which a coil is placed on the outer wall of the path through which the developer flows and the inductance is indirectly measured while the developer is in a flowing state or once stationary. Methods are already known in which inductance is measured by contacting only one side of the coil in the path of the coil, but these methods have drawbacks such as complicated measuring equipment and poor measurement sensitivity.

Therefore, the inventors of the present invention have decided to apply for Utility Application No.
No. 56048 proposed a toner density control device that improved the above drawbacks.

That is, the prior application discloses a toner density control device in which a coil is disposed within a developer path and the inductance is measured using both sides of the coil, thereby increasing measurement sensitivity.

The present invention is also applicable to a developing device having a toner density control device using the known inductance measurement method.
This can be particularly effective in a developing device having the toner density control device according to the prior application.

The present invention will be explained below based on the drawings.

FIG. 1 shows an example of the toner concentration control device described in the prior application.

1 is a photoreceptor, 2 is a developer container, 3 is a developing sleeve containing a magnetic member, 4 is a developer, 5 is a developer scraper, and 6 is an inductance measuring coil.

The developer 4 is flowing as the developing sleeve 3 rotates, and the coil 6 is placed at an appropriate position in the flow of the developer 4 to measure the magnetic permeability of the developer 4 as an inductance.

The coil 6 may be flat or cylindrical, but a flat coil is preferably used.

FIG. 2 is a block diagram showing the configuration of the toner density control device.

The inductance measured by the coil 6 is converted into voltage by the conversion circuit 21.

Reference voltage circuit 2 corresponding to the reference toner density here
A circuit 23 is provided to compare the output of the converter circuit 2 with the output of the converter circuit 21, and the toner replenisher 24 is driven from the output signal of the comparator circuit 23.

In this way, an appropriate amount of toner is replenished during the process of consuming toner due to development, and the toner concentration is kept constant at all times.

However, in reality, fibrous dust adhered to the coil 6 and the actual concentration could not be maintained constant.

Here, while making the flow of developer in the developing device steady,
Dust is collected by installing a protrusion made of an appropriate member at an appropriate position that does not disturb the flow of developer near the coil 6 - an improvement that prevents fibrous dust from affecting the coil 6. FIGS. 3 and 4 show embodiments of the present invention.

In FIG. 3, a dust collecting member 7 is placed in front of the coil 6, a dust collecting member 8 is placed at an appropriate location in the path of the developer 4 flowing in the developing device, and a developer is placed at the tip of the developer scraper 5. The flow adjustment member 9 was attached.

The tip of the adjusting member 9 is brought into close contact with the developing sleeve 3 to prevent the developer and dust from passing through the gap between the developing sleeve 3 and the developer scraper 5.

As a result, the flow of the developer 4 in the developing device is controlled by the coil 6.
It became extremely constant around .

Further, the adjustment member 9 was able to prevent fibrous dust from being deposited on the scraper 5, and was therefore effective in preventing fluctuations in the measured inductance value due to the deposited fibers.

Further, the dust collecting members 7 and 8 can be made of wood, glass, metal, resin, or any other material as long as it has the necessary strength, but metal or resin is preferably used, and the cross section is, for example, rectangular, preferably, or has a rough surface. A rod-shaped or plate-shaped object with a circular shape, a circular shape, a star shape, a flocked shape, a net-like shape, etc., with small protrusions, etc., and is particularly easy to catch and collect fibrous dust. Things are chosen.

Further, the dust collecting member 7 includes an inductance measuring coil 6.
It is necessary to select a thinner (or thinner) member than the diameter or thickness of the coil and install it so as not to obstruct the steady flow of the developer flowing on both sides of the coil.

Note that the coil 6 is usually a coil winding coated with an insulating material such as resin, and it is also possible to form the collecting member 7 by extending the coated portion forward from the winding portion.

Also, as shown in FIG. 3, when several collection members 8 are installed in the developing device, since a considerable amount of dust can be collected here, the dust collection member 7 installed in front of the coil 6 is used. This reduces the burden on customers and enables more stable and reliable toner concentration control.

FIG. 5 shows the effect when the dust collecting member 7 and the flow regulating member 9 are installed, 51 shows the change in toner concentration when the above members are not installed, and 52 shows the change in toner concentration based on the present invention. FIG. 7 is a characteristic curve diagram showing the result of improvement in changes in toner density when the member is attached.

In this characteristic curve diagram, the initial setting of toner density is set to 6.
When it is set to 0%, the toner density changes that occur with subsequent continuous copying operations are shown.

3 if the dust collection member 7 and flow adjustment member 9 are not provided.
After every copy, the actual toner density drops to about 4%, whereas when the above-mentioned member according to the present invention is provided, the actual toner density drops by ±0.5%.
It can be seen that the change in the actual toner concentration is only %, and the measurement error is extremely small.

According to experiments conducted by the inventors of the present invention, the decrease in the actual toner concentration of the developer is caused by the adhesion of fibrous dust, and if the toner concentration drops to 4%, the sudden dust can be removed immediately. Shortly after the toner replenishment operation was started, the actual toner concentration recovered to the initial setting concentration of 6.0%.

Another embodiment is shown in FIG.

In FIG. 6, a coil 6 is installed at an appropriate location on the scraper 5, and a developer flow adjusting member 9, which is larger than the outer circumference of the coil 6, is provided at the tip of the scraper 5 in contact with the sleeve 3. A dust collection member 7 is provided at the tip, and dust collection members 1 are additionally provided on the left and right sides of the coil 6.
2 is shown.

By doing so, the dust collection effect is further promoted, and as a result, the inductance of the coil can be measured with high accuracy.

As described above, in a developing device having a device that controls the toner concentration of the developer by measuring inductance with a coil member installed in the developer, one or more coils are installed near the measuring member and in the developer container. By installing a plurality of dust collecting members, it was possible to obtain a developing device having a toner concentration control device with extremely stable performance.

[Brief explanation of the drawing]

Figure 1 is a side view of the developing device disclosed in the earlier application, Figure 2 is a side view of the developing device disclosed in the earlier application;
The figure is a block diagram showing the configuration of the toner density control device.
FIG. 3 is a side view of the developing device of the present invention, FIG. 4 is a perspective view of the density measuring device of the present invention, FIG. 5 is a characteristic curve diagram, and FIG. 6 is a diagram showing another embodiment of the present invention. 3 shows a perspective view of the developing device shown in FIG. 5...Developer scraper 6...Inductance measurement coil, 7. Death...Dust collection member, 9...Developer flow adjustment member, 51...
...Change in toner density when members 7 and 9 are not installed, 52...Change in toner density when the members 7 and 9 according to the present invention are installed, 12... - Additional dust collection members provided on both sides of the coil 6.

Claims (5)

[Scope of utility model registration request] (1) A developer container that stores developer, a sleeve that is inside the container and that moves the developer, a scraper that scrapes off the developer on the surface of the sleeve, and a path for the moving developer. In a developing device having an inductance measuring coil for controlling the toner concentration of the developer, the developing device has a coil for measuring inductance for controlling the toner concentration of the developer; A developing device further comprising a member for collecting dust in the developer. (2) Scope of Utility Model Registration Claim 1, which includes a developer flow adjusting member supported by a scraper located near the bottom of the inductance measuring coil, and whose tip is provided in close contact with the sleeve surface. The developing device described. (3) The developing device according to claim 1, wherein the dust collecting member is installed on the side where the developer flows into the coil and, if necessary, on both sides of the coil. (4) The developing device according to claim 1, wherein the developer is a two-component developer containing a magnetic carrier and a toner. (5) A utility model registration claim in which the coil is a coil made in a flat shape, and the inductance of the coil is measured by constantly flowing a developer along the front and back surfaces of the coil. Developing device according to item 1 or 2.