JPS6334566A - Developing device - Google Patents

Abstract

PURPOSE:To improve detection accuracy by permitting a cleaning member to clean a developer detecting surface when a developer level lowers near to the developer detecting surface. CONSTITUTION:The bottom end of the cleaning member 7 is disengaged from a crank part 4b of an agitating bar 4 and only the agitating bar 4 rotates clockwise from the point beta after the bottom end of the cleaning member 7 arrives at the point beta. Vanes 8 move from the left toward the right together with the cleaning member 7 in this case; therefore, the detecting surface 6 of a level sensor is rubbed by the cleaning member 7. The developer in front of the detecting surface 6 of the level sensor is scraped by said vanes 8 and a space is generated in front of the detecting surface 6 of the level sensor but there is still a substantially large amt. of the developer in a developing device body 1; therefore, the collapsion of the developer arises right after the passage of the vanes 8 in the space and the space is annihilated. The generation of a wrong detection output in the level sensor is thus obviated.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a developing device to be installed in an electrophotographic apparatus, etc., and in particular, the present invention relates to a developing device for equipping an electrophotographic device, etc. This invention relates to a developing device that has a function that can accurately detect values (values, etc.).

[Background of the invention]

FIG. 2 is a schematic diagram of the main parts of a conventional developing device installed in an electrophotographic apparatus. In FIG. 2, reference numeral 1 denotes a box-shaped developing device main body (including a developer carrier forming a developing area as a developer container) that houses a developer. It may also be a container such as a honnoku that supplies the developer to the container.) 2 is a developing sleeve 1 (developer carrier: may be an edged sheet in a belt) installed in the lower opening of the developing device main body 1 and driven to rotate in a counterclockwise direction; 3 is a developing sleeve 2; A non-rotating (or rotating) magnetic roller inserted in the magnetic roller conveys magnetic developer (-component or two-component) by magnetic force. In addition to this example, a single magnetic roller for generating a magnetic field may be used. Reference numeral 4 denotes a crank-shaped stirring rod installed in the developing device main body 1 and driven to rotate clockwise about an axis parallel to the developing sleeve 2; 5 a developer adsorbed on the outer circumferential surface of the developing sleeve 2; A doctor blade 6 is placed at a predetermined height on the inner wall surface of the end plate of the developing device main body 1 (which is parallel to the plane orthogonal to the axis of the developing sleeve 2 in the figure). A pressure-sensitive level sensor consisting of a fixed piezoelectric element, etc., 7 is a fulcrum P
a cleaning member made of a leaf spring, which is fixed to the surface of the paper and is capable of elastically deflecting and swinging in a plane parallel to the plane of the paper, and is also capable of rubbing and cleaning the detection surface 6 of the level sensor;
It is.

The stirring bar 4 has a journal part 4a and a crank part 4b (or arm part) as shown in FIG. Moving.

The main role of the cleaning member 7 is to scrape off the developer adhering to the detection surface 6 of the level sensor, and while the cleaning member 7 moves between the solid line position and the two-dot chain line position, slides against the detection surface 6 of the level sensor to scrape off the developer adhering to the detection surface 6 of the level sensor.

The lower end of the cleaning member 7 engages with the crank portion 4b of the stirring rod 4 only between two points α and β on the circular orbit C of the tip of the stirring rod 4.

That is, when the stirring bar 4 rotates clockwise as shown by the arrow, the crank part 4b engages with the lower end of the cleaning member 7 at point α, then pushes the lower end of the cleaning member 7 to point β, and then moves to point β.
At this point, the crank portion 4b and the cleaning member 7 are disengaged. The cleaning member 7 released from the engagement with the crank portion 4b of the stirring rod 4 at point β returns from the two-dot chain line position to the solid line position due to its own elastic force, and at this time, the level sensor 6 is again moved. The surface is rubbed and the developer is stirred. Such a cleaning member 7 is provided because
This is to prevent false detection by the level sensor 6. That is, since the level sensor 6 is composed of a contact-sensing piezoelectric element, even if the level of the developer is lower than the level at which the level sensor is installed, the developer will not adhere to the detection surface 6 of the sensor. This is because if it is, it is easy to falsely detect that the developer level is sufficient.

Therefore, in the conventional developing device, a cleaning member 7 is provided to scrape off the developer adhering to the surface of the level sensor 6, thereby preventing the occurrence of the above-mentioned false detection.

However, it has been found that even in the conventional developing device equipped with the cleaning member 7 as described above, a false detection phenomenon occurs due to the cleaning member.

In other words, in a developing device having a cleaning section structure as shown in FIG. This is because since the cleaning member 7 rubs against the detection surface 6 of the level sensor, a gap is created in front of the detection surface 6 of the level sensor after the cleaning member 7 has passed, and as a result, false detection is likely to occur. (When the developer level inside the developer body is sufficiently higher than that of the level sensor, the gap is often quickly filled with the developer, but when the developer has poor fluidity or when the level sensor is Since the gap may not be filled with developer when it is approximately at the same height as the detection surface 6 of 1
A detection signal indicating that the developer has run out will be generated from the level sensor.) [Object of the Invention] An object of the present invention is to provide a developing device with high detection accuracy that does not cause the above-mentioned false detection. Developing device that can detect developer (including developing device and developer replenishment device such as Honno 4-)
The goal is to provide the following.

[Summary of the invention]

In this invention, when the rail of the developer is higher than the position of the developer detection surface (i.e., developer sensor), the cleaning member is moved to a position away from the developer detection surface (preferably also at a position far from the developer carrier). The cleaning member The present invention is characterized in that it allows cleaning of the developer detection surface.

In the first embodiment of the present invention shown below, a cleaning time control member is provided in order to easily perform the above-mentioned operation control. This is a flat plate member attached to the tip of the cleaning member and having a relatively large area so as to form a plane perpendicular (preferably perpendicular) to the direction of movement of the cleaning member. When the developer is above the detection surface, the force of the existing or moving developer pushing the cleaning member away is combined with the force exerted by the entire cleaning member to move toward the detection surface area due to its own weight, or Therefore, the cleaning member is held at a position away from the erroneous developer detection surface, while the developer level drops near the developer detection surface and the pushing force of the developer acting on the flat plate member is reduced. When the blade becomes smaller, the gravity component acting on the flat plate member and the restoring force of the cleaning member cause the cleaning member to move in the direction of sliding the developer detection surface. Since the function is based on a mechanical principle determined by the restoring force, the developer displacement force, and the weight and area of the blade, the configuration of this embodiment does not require any complicated mechanism or device to control the operating timing of the cleaning member. Not needed.

[Embodiments of the invention]

An embodiment of the present invention will be described with reference to FIG. In addition,
In FIG. 1, parts indicated by the same reference numerals as in FIG. 2 indicate the same parts as in the conventional developing device shown in FIG.

In the developing device of this embodiment shown in FIG. 1, a flat blade 8 (cleaning timing control member) located in front of the developer detection surface 6 of the level sensor is attached near the lower end of the cleaning member 7. It is characterized by the presence of The surface of this blade 80 is a plane perpendicular to the detection surface 6 of the level sensor, and the area and weight of the blade 8 are designed based on required mechanical considerations. The cleaning member 7 has a leaf spring above the center of swing P, and when moved by the stirring rod with the leaf spring in contact with the locking point 15, it accumulates restoring force.

(In FIG. 1, the blades 8 are depicted as being inclined to the surface of the level sensor 6, but in reality they are perpendicular to each other.) The developing unit of this embodiment shown in FIG. 1, the cleaning member 7 is assumed to be in the position shown by the double-point complex 7' in FIG. 1 before the developing device starts operating, and the developing sleeve 2 and stirring rod 4 are stationary.

On the other hand, it is assumed that the amount of developer in the developing device body 1 is equal to or higher than the developer replenishment required level L (that is, the level below the detection surface 6 of the level sensor) as shown in the figure.

At the start of the operation of the developing device, the developing sleeve 2 and stirring rod 4
When these are rotated in the direction of the arrow shown in the figure, the lower end of the cleaning member 7, which was stationary at the point α in the figure, engages with the crank part 4b of the stirring bar 4. As a result, the cleaning member 7 is swung about the fulcrum P from the position indicated by the two-dot chain line 7' to the solid line position 1 in the figure. After the lower end of the cleaning member 7 reaches the point β, the lower end of the cleaning member 7 disengages from the crank portion 4b of the stirring rod 4, so that only the stirring $4 reaches the point β.
Then rotate further clockwise. In this case, since the blade 8 also moves from left to right in the figure together with the cleaning member 7, the sensing surface 6 of the level sensor is rubbed by the cleaning member 7, and the sensing surface 6 of the level sensor is rubbed by the blade 8.
Although the developer in front is scraped away and a space is created in front of the detection surface 6 of the level sensor, there is still a sufficient amount of developer in the developing device main body 1. Immediately thereafter, the developer collapses and the space disappears, so that the level sensor does not produce a false detection output.

Furthermore, due to the rotation of the stirring rod 4 and the developing sleeve 2, a rightward developer flow occurs in the front position of the detection surface 6 of the level sensor in FIG. Received from developer. That is, the blade 8 receives a pushing force rl from the developer in contact with the left side surface. As a result, the force F1 of the developer causes the blade 8 to stop at the solid line position in FIG. 1 because the force F is greater than the sum of the restoring force of the leaf spring and the force due to the cleaning member's own weight.

In this case, the reaction force FL that tries to return the blade 8 and the cleaning member 7 to the original position indicated by the two-dot chain line 7' is a component tl1gdnθ (m: mass of the blade 8, g: gravitational acceleration) due to the weight of the blade 8. , θ: deflection angle of the swinging member 7) and the restoring force due to the leaf spring of the cleaning member 7 act on the blade 8, but these leftward reaction forces cause the blade 8 and the cleaning member 7 to move to the solid line position in FIG. Until it moves, it is considerably smaller than the rightward force, so it does not act as a force to move the cleaning member 7 and blade 8 toward their original position (the position indicated by the two-dot chain line τ in FIG. 1).

For this reason, the developer level in the developer main body 1 can be adjusted to the detection surface 6.
If there is a large amount around the blade 8 and the cleaning member 7,
Since the developer is always in contact with the detection surface 6 of the level sensor, no false detection signal is generated.

On the other hand, when the developer level in the developing device main body 1 approaches the detection surface area of the level sensor and decreases downward, approaching the illustrated level L1, the amount of developer in contact with the left side surface of the blade 8 also decreases. At the same time, the pushing force F1 from the developer acting on the left side surface of the blade 8 also decreases to F-(<rl).
The sum FL of the restoring force due to the leaf spring of the cleaning member 7 that attempts to return the cleaning member 7 to the position shown by the two-dot chain line in the drawing and the restoring force component due to the weight of the blade 8 exceeds the force F acting on the blade 8 in the right direction. As a result, while the crank portion 4b of the stirring bar 4 rotates from point β to point α, the cleaning member 7 returns from the solid line position shown in the figure to the two-dot chain line position 117', and at that time, The detection surface 6 of the level sensor is rubbed by the cleaning member 7 and the blade 8, and the developer adhering to the detection surface 6 of the level sensor is scraped off. (This scraping operation is also performed while the stirring rod 4 moves from point α to point β, so after the developer level approaches L, the detection surface 6 of the level sensor is cleaned. (This process will be repeated several times.) As described above, when there is no more developer in the developing device in the area corresponding to the detection surface 6 of the level sensor (that is, the developer level becomes lower than L). Then, an output signal is generated from the level sensor, and in response to the output signal, developer is replenished into the developing device main body 1 from a developer replenishing device (not shown).

FIGS. 4 and 5 are explanatory views of main parts of other embodiments of the present invention, and are sectional views passing through the cleaning member and perpendicular to the center of rotation of the developer carrier.

In these embodiments, the driving load on the cleaning member is reduced due to a decrease in the amount of developer, and the cleaning member is allowed to move. The purpose of the cleaning member is to ensure that the cleaning member is moved before the developer level decreases to the detection area. This reliably prevents dangers such as malfunctions in level detection during cleaning and further increases safety.

In the previous embodiment, the M type member can be configured to operate when the developer level is near the lower limit of the detection range, but this is a cleaning to confirm the detection and to prevent any malfunction. It is only advantageous in terms of prevention.

The embodiments shown in FIGS. 4 and 5 are specific examples for the above purpose, but the technical idea common to these is not limited to the specific configuration.

The embodiment shown in FIG. 4 is characterized in that the cleaning member 7 has a developer-loaded passive surface 11, which receives a movement prevention force due to the presence of developer, located only above the developer detection surface 6. The cleaning section is a cleaning brush 16 formed of a large number of woven fibers, plastic bristles, etc. of equal length and cleaning a cleaning area that is equal to or larger than the detection surface. The cleaning member 7 in FIG. It has a cleaning brush 16 spaced apart from the surface, and further has a receiving part 10 below which the 4b portion of the stirring rod 4 comes into contact and receives the driving force of the cleaning member 7. Since this passive surface is close to the inner wall, if the developer forms a bridge between the inner walls and remains, it can sweep away the developer, which is more favorable for detection. The driving force receiving portion 10 has a much smaller area than the passive surface, and is made of a rubber piece or a metal piece of about 50 to 100 μm and has elasticity. The elasticity of the portion 10 of this receiver is such that it can be used as a cleaning member without stopping the stirring rod when receiving the driving force from the stirring rod 4 during the stop period when there is a large amount of developer and the load receiving surface receives the load of the developer. The receiver 10 is allowed to be separated from the stirring rod 7 and restored to position the receiver 10 itself on the orbit of the stirring rod 4 again. For this reason, it is preferable that the receiving part 10 has a small area, but this elasticity is deformed when the stopping force applied to the passive surface by the developer load is greater than the driving force from the stirring rod.
If the driving force is used to prevent deformation when the stopping force is almost zero, unlike the example in FIG.
On the left side of the figure, the receiver can keep the part in the α position. The passive surface 11 is provided only at the position 111 indicated by the broken line (
The inside of the container) is less subject to the load of developer residue that tends to remain on the inner wall of the container, so the boundary between the stop period and the operating period of the cleaning member is more stable, and the operating period (reciprocating It is possible to stabilize the start of movement (or rotation) and prevent malfunctions. Of course, the passive surfaces 11 and 111 may be combined, and the shape can be modified as long as it meets the above purpose. Therefore, in the embodiment of FIG. 4, from when the developer level is at level L1 below the passive surface, to below the level L! between the passive surface and the sensing surface! Since the cleaning member can be reliably moved when the developer adheres to the detection surface affects the detection, the developer is at a level of 51 or higher, that is, υ above the detection surface. When it is in the position, the stop timing can be set accurately.

The embodiment shown in FIG. 5 is a modification of the one shown in FIG. 4, in which only the upper part of the passive surface 11 is opposed to the detection surface 6, and a cleaning brush 17 with a small load is provided between the opposed parts.

According to this, since the developer decreases from the inside of the container, when the developer decreases to the detection surface area, the cleaning member is removed even if there is a developer load existing between the passive surface and the detection surface. can be activated.

Therefore, when the level of developer near the detection surface decreases, the developer present on the detection surface side can be cleaned to improve detection performance.

Incidentally, nine combinations of each of the above embodiments are included in the present invention, and the means for changing the driving of the cleaning member from a stop period to a driving period according to the amount of developer present includes a method in which the developer load is changed. A slip clutch that uses the large drive torque from the drive motor to continue driving when the drive torque is large,
You can also use a ratchet. In this case, there is no need to consider drive transmission from the stirring rod.

In the present invention, a more preferable control method is provided. That is, when such a cleaning member changes from a stop period to an operating period, the developer load is suddenly caused by the developer falling from above, and the cleaning member faces the detection surface, causing the developer capacity to decrease. Changes may cause malfunctions. This case can be solved by performing detection control such that developer detection is performed after the cleaning member has passed the detection surface 6 at least once after activation. in particular,
As mentioned above, with a reciprocating type, you only need to confirm that it has reciprocated using a microswitch before activating the developer detection circuit, and with a rotating type cleaning member, you need to rotate it one or more times before activating the circuit. Good.

〔Effect of the invention〕

As explained in the above embodiments, in the developing device of the present invention, the operation of the cleaning member is controlled so that the cleaning member is operated at a non-operating period (when there is a lot of developer) and an operating period (when the developer is decreasing). There is no risk of false detection like in conventional developing units, and it is possible to accurately detect when the developer level in the developing unit has reached a predetermined level and replenish the developer at the appropriate time. As a result, the image density in the electrophotographic apparatus can be kept stable.

It is clear that the structure for controlling the timing of operation of the cleaning member is not limited to the structure of the embodiment described above, and that various modifications are possible.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an embodiment of a developing device according to the present invention, FIG. 2 is a schematic cross-sectional view of a conventional developing device,
FIG. 3 is a perspective view of a stirring rod installed in the developing device of FIGS. 1 and 2, and FIGS. 4 and 5 are schematic explanatory views of other embodiments of the present invention, respectively. 1... Developing device main body (developer container) 2... Developing sleeve (developer carrier) 3... i-Gnet roller 4... Stirring rod 5... Doctor blade 6... Repercussor Detection surface 7...Cleaning member 8...Blade (cleaning time control member) Honda Kodaira, -゛Kishi 1) Normal line -'1. 1. -7.・! Koji Shinbe Ll-m- Hiroshi Tani Taibe ■ Figure 2 □1 Figure 3 Figure 5

Claims (1)

[Scope of Claims] A developer container containing developer, a developer detection surface disposed at a predetermined height within the developer container, and a cleaning member that cleans the developer detection surface. , a moving force imparting means for imparting a moving force that causes the cleaning member to slide against the developer detection surface, and there is a level that is the upper limit of the developer replenished or stored above the detection surface. In such a developing device, when the developer level in the developer container is above the developer detection surface, the cleaning member is held at a position away from the developer detection surface, and the developer level is A developing device characterized in that when the developer level drops near the developer detection surface, the cleaning member is allowed to clean the developer detection surface.