JPS62113180A - Electrostatic latent image developing device - Google Patents

Abstract

PURPOSE:To stably and accurately detect toner concentration though the quantity of a developer is changed, by providing a toner concentration sensor on the scraping-up face of a blade and detecting the toner concentration in a position where the density of the developer to the sensor is highe and fixed. CONSTITUTION:A blade 34 consists of a scraping-up face 34a and a catching part 34c in the front end, and a toner concentration sensor 35 is so provided that is detecting part is engaged with a hole 34d of the blade 34. The developer on a developing roll 33 is scraped from the developing roll 33 by the catching part 34c of the blade 34 and is raised along the scraping-up face 34a against its own weight. Since the blade 34 has not a horizontal face, the rising developer, when losing the rising force, is dropped to a flow control member 36. Consequently, the flow direction of the developer to the toner concentration sensor 35 is fixed and uniform, and the density is fixed. Thus, the toner concentration is kept stably and accurately because the toner concentration sensor 35 detects the change of permeability of the developer having the fixed density.

Description

[Detailed Description of the Invention] [Table of Contents] Overview Industrial Field of Application Conventional Technology Problems to be Solved by the Invention Means for Solving the Problems (Fig. 1) Working Example (α) 1 Description of Embodiments (FIGS. 2 and 3) (b) Description of Other Embodiments Effects of the Invention [Summary] In an electrostatic latent image developing device having a blade for regulating the height of the developer on the developing roller, By providing a toner concentration sensor on the scraping surface of the blade, it is possible to stably detect toner concentration regardless of the amount of developer.

[Industrial application field]

The present invention relates to an electrostatic latent image developing device for converting an electrostatic latent image into a visible image in an electrophotographic device or an electrostatic recording device, and in particular detects the toner concentration of a two-component developer consisting of toner and carrier. This invention relates to an electrostatic latent image developing device that has been improved to enable accurate development.

Copying machines and recording devices using electrophotographic technology or electrostatic recording technology are widely used. In devices that use such electrophotography, an electrostatic latent image is formed, and a developing device is used to convert this into a visible image. Generally, a developing device that uses a powder developer is used. There is.

[Conventional technology]

For example, in the electrophotographic apparatus shown in FIG. 4, a charger 2. Developing device 3. Transfer device 4. Paper separator5. A cleaner section 6 and a static eliminator 7 are arranged. After the photosensitive drum 1 rotating clockwise is uniformly charged by the charger 2, the reflecting mirror 1
The electrostatic latent image corresponding to the light image is formed on the photosensitive drum 1 by exposure to a light image provided from a laser light source or the like via the photosensitive drum 2, and is developed into a visible image by the developer 3. Further, the paper taken out from the paper feed cassette 8 by the pick roller 9 is sent to the transfer device 4 by the standby roller 10 in synchronization with the rotation of the optical drum 1, so that the image on the photosensitive drum l is transferred to the paper. The transferred paper is separated from the photosensitive drum 1 by a paper separator 5, sent to a fixing roller (not shown) by a feeding roller 11, and after being fixed, is sent to an ejection stacker and stored. After the transfer, the surface is cleaned by the cleaner section 6, and then the static electricity is removed from the surface by the static eliminator 7, and the process starting from the charger 2 is repeated again.

The developing device 3 used in such an electrophotographic apparatus includes a toner supply cassette 30, a toner supply roller 31, and an agitation roller 32.
, a developing roller 33, a blade 34, a toner concentration detection sensor 35, and a flow regulating member 36.A stirring roller (hereinafter referred to as a paddle roller) 32 rotates counterclockwise to mix toner and carrier. The component developer 37 is stirred and transferred to the developing roller 33 . Developing roller 33
has a magnet inside, attracts the carrier (iron powder) of the transferred developer 37, forms a magnetic brush of the developer 37 on its surface, and rotates counterclockwise to convey the developer 37. ,
The height of the developer 37 in the form of a magnetic brush is kept constant by the blade 34 (the height of the brush is regulated), and by bringing it into contact with the photosensitive drum 1, the toner is attracted and adhered to the electrostatic latent image on the photosensitive drum 1, and development is performed. Let's do it. On the other hand, the excess developer 37cL stripped off by the blade 34 rises along the blade 34 and flows along the flow regulating member 36 to the paddle roller 32.
and is transmitted to the developing roller 33 again.

The toner concentration of the developer 37α stripped off by the blade 34 is detected by a toner concentration detection sensor 35, and based on this detection, the toner in the toner supply cassette 30 is supplied from the toner supply roller 31 to the stirring roller 32. , the consumed toner is replenished.

In such a developing device 3, the conventional blade 34 is
As shown in FIG. 5, it is formed in an L-shape with an inclined (scraping) surface 34α for scooping up the developer and a horizontal surface 34b following it, and a toner concentration sensor 35 is provided on the horizontal surface 34b.

The toner 4 degree sensor 35 is generally composed of a magnetic sensor that detects changes in the magnetic permeability of the developer, and detects the toner concentration by detecting the proportion of carrier in the developer.

[Problem that the invention seeks to solve]

In such a conventional developing device, the developer is scraped up by the scraping surface 34α of the blade 34, and the blade 3 is scraped up against its own weight.
By flowing the developer onto the horizontal surface 34b of 4, it is possible to detect 6 degrees of toner by supplying the developer to the toner concentration sensor 35.

However, since the toner 4 degree sensor 35 detects the developer scraped up against its own weight, the horizontal surface 3
The flow of the developer at 4b was not unidirectional; some of the developer fell toward the flow regulating member 36 due to its own weight, and the flow direction was not constant.

Therefore, when the amount of developer scraped changes and the amount of developer scraped up by the scraping surface 34α changes, the flow direction of the developer on the horizontal surface 34h also changes variously, and the flow direction of the developer changes with respect to the sensor 35. Density changes occur, and as a result, even if the mixing ratio of toner and carrier is constant, output changes depending on the amount of developer, resulting in a problem that stable and accurate toner concentration detection cannot be performed.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic latent image developing device that is stable and capable of accurately detecting toner concentration even when the amount of developer changes.

[Means for solving problems]

FIG. 1 is a diagram explaining the principle of the present invention.

In the figure, the same parts as those shown in FIGS. 4 and 5 are indicated by the same symbols.

In the present invention, a toner concentration sensor 35 is provided on the scraping surface 34α of the blade 34.

[Effect]

In the present invention, the toner concentration sensor 35 is configured to detect the developer being scraped down by the scraping surface 34α of the blade 34 and rising. The developer scraped up along this scraper 34α has a constant direction and flows uniformly, so even if the amount of developer changes, the flow direction is constant and uniform, and the developer flow is constant. Therefore, stable and accurate toner
! Changes can be detected.

That is, the developer is made to flow in a constant and uniform direction to the toner 7 agricultural rate sensor 35, so that the toner is stable and accurate.
This enables detection on a case-by-case basis.

〔Example〕

(α) Description of an Embodiment FIG. 2 is a block diagram of one practical example of the present invention, FIG. 2 (2) is a perspective view thereof, and FIG. 2 (2) is a sectional view thereof.

In the drawings, the same parts as those shown in FIGS. 1, 4, and 5 are indicated by the same symbols, and the blade 34 is composed of a scraping surface 34α and a hook portion 34C at its tip. 8, the toner and inter-meal sensor 35 is provided such that its detection portion engages with the hole 34d of the blade 34.

In this embodiment, the blade 34 does not have a horizontal surface and only has a scraping surface 34-L, and the angle of the scraping surface 34α is set to α.

The developer on the developing roller 33 is stripped off from the developing roller 33 by the hook portion 34C of the blade 34, and rises against its own weight along the scraping surface 34α.

At this time, since the developer does not have a horizontal surface as described above, the rising developer falls to the flow regulating member 36 when it loses its rising force.

Therefore, the flow direction of the developer is constant and uniform with respect to the toner concentration sensor 35, and the density is also constant.

Therefore, since the toner concentration sensor 35 detects changes in magnetic permeability of the developer having a constant density, stable and accurate toner concentration (that is, carrier mixing ratio) is possible. Since the blade 34, which does not have a horizontal surface, does not provide resistance to the rising developer, the flow of the developer to the toner 4 degree sensor 35 becomes even more constant and continuous.

FIG. 3 is a toner art detection characteristic diagram according to an embodiment of the present invention.

In Figure 3 (5), the mixing ratio of toner and carrier is constant;
5 is an output characteristic diagram of the toner density change sensor when the amount of developer is changed; in the figure, α is the case according to the present invention, and b is the case according to the conventional configuration shown in FIG. 5. FIG.

As is clear from the characteristic diagram in FIG.
5, the output of the sensor 35 does not change much even if the amount of developer is changed.

On the other hand, in the prior art, since the toner concentration sensor 35 is provided at a position where the density of the developer does not flow uniformly, when the amount of developer is changed, the output of the sensor 35 changes greatly accordingly.

Moreover, FIG. 3(C) is a graph of toner heavy cough versus sensor output characteristics when the angle α of the mounting angle α of the blade 34 of the present invention is changed, and 01 in the figure indicates α=31.
, C2 is set to α=26°, and C3 is set to α=18°.

The same toner concentration vs. sensor output characteristic diagram as in Figure 3 (as is clear from the characteristic diagram of Hitoshi, when the amount of developer is constant, α = 31° and conventional θ) is obtained, α = 26 Similar characteristics were obtained at 10°C.

On the other hand, when α=18°, the sensor output hardly changed, making it difficult to detect the toner concentration.

Therefore, it has been found that the optimum output can be obtained when the angle α is between 26° and 31° with the above-mentioned installation.

This means that when installing, the angle α should be small, and the raised surface) 34α
As the developer approaches the toner concentration sensor 35 vertically, more of the developer that has been lifted up falls off in the direction along the direction 34α, and the density and impact of the developer relative to the toner concentration sensor 35 are no longer constant. I think it is n, 6°, and the installation is angle α,
2, and when the scraping surface 34α is approached horizontally, the scraped developer flows in the direction of the '80 member 36, and similarly, the developer that is scraped up flows toward the toner angle sensor 35. I think that the flow layer and density are no longer constant.

Therefore, it is necessary to give a certain slope to the raking section 34α.

(bl Description of other embodiments In the above-mentioned embodiment V11, the blade 34 was explained as having no horizontal surface. However, the setting of the blade 35 to be raised and set to 34α may also be applicable to a blade having a horizontal surface. In this case, the horizontal surface plays a role in preventing scattering of the present agent.

In the above embodiment, the developer described as a developer for electrophotography 4ii Al is used as a developer such as the
(You may use

The non-inventions have been explained using examples above, and the non-inventions are not intended to exclude various modifications from the present invention.

〔Effect of the invention〕

As explained above, according to the present invention, since the toner concentration sensor is provided at the point where the blade scrapes up, the density of the developer relative to the sensor can be detected at a large and constant location. The effect of moxa is that stable and accurate toner concentration detection is possible even if the toner concentration changes due to consumption or the like.

In addition, the means of achieving this is simple and easy, as the sensor installation is simply a matter of changing the position, which has an unbelievable effect, and it is easy to stabilize and accurately control the toner density composition. We are planning to make this happen.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the principle of the present invention, FIG. 2 is a configuration diagram of an embodiment of the invention, FIG. 3 is a toner density detection characteristic diagram according to the present invention, and FIG. 4 is a configuration diagram of a slave photographic device. FIG. 5 is an explanatory diagram of the prior art. In the figure, 3... Developing device, 32... Stirring roller (,:, j stirring means), 33...
Developing roller, 34... Flade, 34α... Scraping, 35... Toner flexibility sensor. Patent Applicant Tomi ±] Den Co., Ltd. Agent Masu Physician Akira Yamatani Eiki's 1 Principle Eiro Diagram of B Moon Figure 1 (A) (B) Toner-171
Picture on the right: Seven Horsemen and their country of birth. Picture 3. The first image of the electrophotographic production. Picture 4.

Claims (1)

[Scope of Claims] A stirring means for stirring a two-component developer containing toner and a carrier, a developing roller that supplies the developer transmitted from the stirring means to an electrostatic latent image holder, and on the developing roller. An electrostatic latent image developing device comprising: a blade having a scraping surface for regulating the brush height of the developer; and a toner concentration sensor for detecting the toner concentration of the excess developer regulated by the blade. An electrostatic latent image developing device characterized in that the toner concentration sensor is provided on the scraping surface.