JPS5999463A - Controller for toner density of developer - Google Patents

Abstract

PURPOSE:To control the toner density of a developer stably without any influence of variation in temperature, humidity, etc., by providing a developer level detector with plural magnetic circuits having gap parts, and detecting the phase of the differential output between both magnetic circuits and comparing coupling values of both magnetic circuits with each other. CONSTITUTION:A bottom plate 2 which faces a stabilizing plate 7 for stabilizing the level of the developer in a tank is provided with the developer level detector 14 which consists of two transformers 17a and 17b composed of magnetic cores 15a and 15b having magnetic gap parts 16a and 16b. When the developer in the tank is at a specific level and the toner density is within a specific range, the differential output between both secondary coils L2a and L2b is 0, but when the coloring toner is consumed and the toner density decreases, the developer level decreases, so the differential output is generated between both secondary coils. The differential output is detected by a phase detector 19 to control toner supplementation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner concentration control device for a two-component developer.

2. Description of the Related Art Developers for electrophotographic copying machines, facsimile machines, printers, etc. include two-component developers consisting of a mixed powder of magnetic main 11 rear and colored toner. When an electrostatic latent image is developed using such a developer, the magnetic carrier in the developer does not decrease, but the colored toner adheres to the latent image and is consumed, so the coloring of the magnetic carrier in the developer increases. Toner ratio (
(hereinafter referred to as toner density) decreases.

In order to perform high-quality development, it is necessary to maintain the toner concentration of the developer within a predetermined range, and for this purpose, the toner concentration of the developer is detected and colored toner is replenished into the developer. There is a developer toner density control device.

The conventional toner concentration detection means of the above-mentioned device focuses on the fact that the magnetic carrier in the developer is not consumed, and uses an electric coil provided in the developer container to configure an anti-coupling oscillation circuit. It has been proposed that the success or failure of the oscillation condition is controlled by the development level of the developer, and the darkness of the developer is determined from the presence or absence of the oscillation output to detect the toner concentration.

However, the success or failure of the oscillation conditions of the anti-coupling oscillation circuit described above is extremely sensitive to external environmental conditions such as temperature and humidity.
There is a problem in that the developer level cannot be detected at all in some cases, and it is extremely difficult to sufficiently compensate for this problem.

The present invention eliminates these drawbacks and provides a developer toner concentration control device that is not affected by changes in external environmental conditions such as temperature and humidity and is stable and highly accurate. This is the purpose.

A feature of the present invention is that a developer level detector is provided at a predetermined position of a container containing developer containing magnetic Kyrelia and colored toner, and the amount of developer is determined according to the output of the developer level detector. In the developer toner concentration control device, the developer level detector is provided with a plurality of magnetic circuits each having a gap, and one of the magnetic circuits is provided with a plurality of magnetic circuits each having a gap. Set the degree of bonding to a value equivalent to the degree of bonding shown when the developer level is within a predetermined range, measure the developer level with the bonding value of the magnetic circuit in use,
The toner concentration control device for the developer compares the combined values of the two magnetic circuits by performing phase detection on the differential outputs of the two magnetic circuits.

Embodiments of the present invention will be described below based on the drawings.

Here, FIG. 1 is a longitudinal cross-sectional side view of a developing device using a toner concentration control device for a developer according to an embodiment, and FIGS. FIG. 2 is a schematic configuration explanatory diagram of a level detector and an explanatory diagram of its operation side.

In FIG. 1, 1 is a side plate, 2 is a bottom plate made of a non-magnetic material, and the side plate 1 and the bottom plate 2 constitute a developer container. 3 is a magnet roll held on the side plate 1; 4 is a non-magnetic sleeve rotatably supported around the magnet roll 3; the sleeve is driven in the direction of the arrow; It rotates while adsorbing and holding the developer 5.

Reference numeral 6 denotes a separating plate for scraping off the developer from the surface of the sleeve 4; 7 a stabilizing plate for stabilizing the level of the developer in the container; and 6, rotating in the direction of arrow B to remove the developer. A stirrer 9 for uniformly mixing the magnetic carrier and colored toner inside is a cover having a toner replenishment port 10.

11 is a replenishment toner hopper, 12 is a toner replenishment valve controlled by a solenoid, 13 is a colored toner for replenishment,
A developer level detector 14 is fixed to the bottom plate 2 facing the stabilizing plate 7 for stabilizing the level of developer in the container. The operation of the structure 9 of the developer level detector 14 will be explained below with reference to FIGS. 2 and 3.

As shown in FIG. 2, the developer level detector 14 includes two transformers 17a and 17b, each of which has a square-shaped magnetic core 15a and 15b having magnetic gaps 16a and 16b. The transformers 17a and 17b include primary coils L1a and Llb and secondary coils L2a and L2, respectively.
b is wound. Further, reference signal detection coils LRa and LRb are wound on the secondary side, and a primary coil L1a.

Lllll are connected in series in two magnetic circuits so that the magnetic fluxes flow in opposite directions, are connected to the output terminal of the oscillator 18, and are connected to the secondary coil L2 a .

L2b is connected in series with the polarity reversed to make the differential output of the two equal to 1, and the reference signal detection coils LRa and LR
b are connected in series with the same polarity, and the phase detector 1
9 and a reference signal input terminal, respectively. J5 is in this magnetic circuit, and formally, the primary coil Lta', L1b and the secondary coil L2a,
A differential type transformer in L2b connects the primary coil 11a, Ll
b and the reference signal detection coils LRa and Lnb constitute a normal type transformer. The output of the phase detector 19 is connected to be input to a potential comparator 20 , and the output thereof is connected to a replenishment valve drive circuit 21 .

a5, the developer level detector 14 fixed to the bottom plate 2 facing the developer level stabilizing plate 7 in the container is arranged so that the upper surface of the developer 5 is located in the magnetic gap 16a of the U-shaped magnetic core 15a. An adjustment screw for adjusting the coupling coefficient of the transformer is provided in the magnetic gap 16b of the U-shaped magnetic core 15b.
The degree of coupling is adjusted to be equivalent to the value when the concentration is within a predetermined range.

In the above configuration, when the sleeve 4 of the developing device rotates in the six directions of the arrows, a magnetic brush of the developer 5 is formed on its surface to develop an electrostatic latent image. After development, the magnetic brush is separated from the surface of the sleeve 4 by the separating plate 6 and scraped onto the bottom of the container. The scraped off developer 5 is stirred ta8
The mixture is stirred and circulated again to form a magnetic brush.

The stabilizing plate 7 stabilizes the level of the developer 5 in the container and acts on the developer level detector 14 .

Now, the oscillation output from the oscillator 18 is the primary coil L+a,
When applied to L1++, an output signal corresponding to the coupling degree of each magnetic circuit is sent to the secondary coil L2 a l 12
b. Therefore, if the amount of developer in the container is at a predetermined level and the toner concentration is within a predetermined range, the degree of coupling of the magnetic circuit of the transformer 17a is set to this value in advance. Since it is equivalent to the degree of coupling, the outputs of both secondary coils L, 2a, and L2b are in opposite phases, so they cancel each other out, and their operating output is O.
becomes.

Further, when the colored toner is consumed and the toner concentration decreases as the electrostatic latent image is developed, the developer level decreases, so the coupling degree of the magnetic circuit of the transformer 17a is higher than that of the 1-transformer 17b. The degree of coupling is greater than that of the magnetic circuit, producing a differential output. Therefore, the differential output is detected by the phase detector 19, and a phase detection output corresponding to the phase is output.

This output signal is compared with a reference voltage corresponding to a preset toner level in the potential comparator 20, and the output thereof drives the replenishment valve drive circuit 21 to operate the toner replenishment valve 12. Supply 13.

In addition, the level difference (α: positive constant) +2α, +α, α− indicates the developer level with respect to the set value of the developer level.
The outputs of the secondary coils L2a and L2b for 0, -α, and -2α, their differential outputs, and phase detection outputs are shown in FIG. 3.

As explained above, the developer toner concentration control device according to the present embodiment has a plurality of magnetic circuits having magnetic gaps in the developer level detector, and compares the output signals of the two magnetic circuits. Since the developer level is detected and colored 1 hener is replenished, it is almost unaffected by changes in the external environment such as temperature and humidity.

In the developer level detector 14 according to the above embodiment, the reference signal of the phase detector is taken out as the output of the transformer, but it may also be taken out from the oscillator 18 section.
Further, although the oscillator 18 uses an independent oscillator, a ten oscillator using a primary coil as an inductor may also be used.

Furthermore, it has been confirmed that the primary coils L1a and ly+b may be connected in parallel and function even if the magnetic fluxes rotate in the same direction.

In addition, the detected toner concentration is based on the fact that the developer is an actual mixed powder and is flowing on the detection surface, and that the developer is removed after opening the toner replenishment valve 12 and replenishing the colored toner. Since there is a time delay until the mixture is uniformly mixed, temporal fluctuations occur, so an integrator or smoothing circuit is inserted between the phase detector 19 and the potential comparator 20, and the phase detection output is changed over time. In order to stabilize the functions of the entire toner concentration control device, it is practical to average the voltage, provide appropriate hysteresis to the potential comparator, and provide a time delay in the replenishment valve drive circuit 21. Needless to say, it is very useful.

Note that although the phase detector 19 is used in the developer level detector 14 according to this embodiment, even if a phase comparator is used,
Excess/deficiency of the developer level can be determined with accuracy J:<.

Next, another embodiment will be described based on FIG. 4.

Here, FIG. 4 is a schematic configuration explanatory diagram of a developer level detector of a developer toner concentration control device according to another embodiment.

The only structural difference between the developer toner concentration control device according to this embodiment and the toner concentration control device according to the previous embodiment is the developer level detector, and the other components are essentially the same.

In FIG. 4, the same symbols as in FIG. 2 indicate equivalent parts. 22 is a figure 8-shaped magnetic core, and has a magnetic gap 23a,
A pair of magnetic circuits 23b have a part of a common magnetic path portion 24. The primary coil L1 is partially wound around the common magnetic path section 24 and connected to the output terminal of the oscillator 18. Secondary coils L2a, L2·b and reference signal detection coil LRa.

LRb is one piece 25a of the H-shaped magnetic core 22, respectively.

25b, and the secondary coil L 2 a *L
The reference signal detection coils LRa and LRb are connected in series with opposite polarities to obtain a differential output, and the reference signal detection coils LRa and LRb are connected in series with the same polarity.
Similarly to the figure, it is connected to the signal input terminal and the reference signal input terminal of the phase detector 19. The output of the phase detector 19 is
It is connected to be input to the potential comparator 20 , and its output is connected to the replenishment valve drive circuit 21 .

The structure of the toner concentration detector according to this embodiment is as described above, and its operation and effect are the same as those of the developer level detector according to the previous embodiment as shown in FIG. Therefore, the explanation will be omitted.

As described above, the present invention generally deals with humidity.

It is possible to expect a stable and accurate developer toner concentration control device that is not affected by changes in the external environment such as humidity, and can be said to be an invention with excellent practical effects.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional side view of a developing device using a developer toner concentration control device according to an embodiment of the present invention, and FIGS. 2 and 3 show developer levels used in the toner concentration control device, respectively. FIG. 4 is a diagram schematically illustrating the configuration of a developer level detector used in a developer toner concentration control device according to another embodiment. 2... Bottom plate, 5... Developer, 13... Colored toner, 14... Developer level detector, 15a, 15b...
-Magnetic core, 16a, 16b...magnetic gap. Patent Applicant Hitachi Metals Co., Ltd. No. 4 Figure Proceedings Amendment Written on November 11, 1982 by Kazuo Wakasugi, Commissioner of the Patent Office1, Indication of Case Patent Application No. 207525 of 1982, Title of the Invention Relationship between developer toner concentration control device 3 and the person making the amendment Patent Applicant Address 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name (
508) Hitachi Metals Co., Ltd. 4, Agent 〒1
05 Address: 5th floor, 6th floor, Toranomon 1-11, Toranomon, Minato-ku, Tokyo, Date of amendment order (No spontaneous amendment) 6. Number of inventions increased by amendment None 7. Subject of amendment
Column for detailed explanation of the invention in the specification / 100≧\ 8. Contents of amendment (1) ``In the developer...
. . . Detecting the degree" was changed to "In the developer in the developer container, only coloring 1 to toner is consumed and the carrier is not consumed and the forging is constant. We focused on the fact that toner concentration can be controlled by installing a developer level detector, monitoring the amount of developer, and replenishing the shortage with colored toner. The anti-coupling oscillation circuit used is constructed, and the level of the developer is detected and corrected by J: -4° relative to the oscillation level of this oscillation circuit. (2) "Providing a time delay" in page 10, line 18 of the same as above is corrected to "providing appropriate quantization drive."

Claims (1)

[Scope of Claims] (1) A developer level detector is provided at a predetermined position of a container containing a developer containing a magnetic carrier and a colored toner, and the developer is detected in accordance with the output of the developer level detector. In the toner concentration control device for a developer, which replenishes a container with colored toner so that the amount of colored toner falls within a predetermined level range, the developer level detector is provided with a plurality of magnetic circuits having magnetic gaps, The coupling degree of one magnetic circuit is set to a value equivalent to the coupling degree shown below when the developer level is within a predetermined range, and the developer level is measured using the coupling value of the other magnetic circuit, and the coupling degree of both magnetic circuits is determined. A developer toner concentration control device characterized in that the comparison of values is performed by performing phase detection on differential outputs of both magnetic circuits. (2) The toner m-rate wJ device for developer according to claim 1, wherein the coupling value of both magnetic circuits is compared by a phase comparator. (3) Claim 1, characterized in that the predetermined position of the container is a bottom plate facing a stabilizing plate provided on the container.
A toner concentration control device for a developer according to item 1 or 2.