JPH07234585A - Developing device - Google Patents

Abstract

PURPOSE:To provide a developing device capable of stably obtaining the stuck quantity of a developer on a development roll after the layer thickness is regulat ed at the high-speed operation by providing a shift driving means on a layer thickness regulating means, and changing the layer thickness of the developer. CONSTITUTION:The interval between a developer carrier 5 and a layer thickness regulating means 6 must be kept constant to stably feed a developer 1. If the layer thickness regulating means 6 is pressed to the developer carrier 5 by an elastic member 9, a large quantity of the developer 1 flows in between the developer carrier 5 and the layer thickness regulating means 6 when a developing device is driven at a high speed, the interval between them is widened, and too much developer 1 is supplied. When an elastic body is used or added to the layer thickness regulating means 6, the vibration generated by the layer thickness regulating member 6 is mitigated. A print 11, a rubber 9, or a foam body, for example, is arranged behind the layer thickness regulating blade (member) 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device using an electrophotographic dry one-component developer.

[0002]

2. Description of the Related Art A developing device conveys a developer (toner) from a developer container to a developing mechanism portion by using a conveying means such as a blade, attaches the developer to a developer carrying member, and deposits the developer on the developer carrying member. The excessive developer is scraped off by the layer thickness regulating means to regulate the developer layer thickness. The developer that has passed through the layer thickness regulating means faces the photoconductor and is used for development. The developer that has not been used for development returns to the development mechanism section again.

In the developing device, the developer is carried and the layer thickness is regulated by the developer carrier and the layer thickness regulating means.

According to Japanese Unexamined Patent Publication No. 5-127509, in order to prevent toner adhesion that tends to occur between the developer carrying member and the layer thickness controlling unit, the layer thickness controlling unit moves in the moving direction of the surface of the developer carrying unit. Is provided with a movement drive means for displacing.

[0005]

In the structure in which the layer thickness regulating means is pressed against the developer carrying member by the elastic member, when the developing device is driven at a high speed, the development is carried out between the developer carrying body and the layer thickness regulating means. A large amount of agent flows in, and the space between the two expands. That is, the supply of the developer becomes excessive. Also,
The gap between the latent image carrier and the developer carrier, and the space between the developer carrier and the layer thickness regulating means changes depending on the inflow amount of the developer, causing vibration. As a result, there is a problem in that density unevenness occurs in the printed image. In particular, unevenness is likely to occur on both the left and right ends, which may result in a black and white striped pattern. As described above, it is difficult to keep the layer thickness of the developer constant during high-speed operation of the developing device.

In order to eliminate the unevenness, a method of simply increasing the pressing pressure of the layer thickness regulating member against the developer carrying member is used. Pressure is required.

In the structure in which the developer carrier is an elastic body, if a load is applied to the developer carrier by a layer thickness regulating means or the like for a long period of time, the developer carrier will be plastically deformed, causing uneven rotation. . In particular, during high-speed operation, this vibration caused image defects. Further, although the elastic member capable of applying the pressing pressure corresponding to the high speed operation is provided, the image density unevenness may still occur due to the problem of toner supply. In this case, since the developer layer thickness has not been conventionally detected, there is a problem that even if the developer layer thickness becomes thin, it is used for development as it is and the developer carrier is damaged.

SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device which gives control and can obtain a printed image with less unevenness without causing plastic deformation of the developer carrying member. Another object of the present invention is to provide a developing device that can detect a change in the developer layer thickness and can obtain a printed image with less unevenness by the driving unit.

[0009]

In order to achieve the above object, the present invention is, in a developing device of an electrophotographic image forming apparatus, a carrying amount of a developer carried from a developer container and a carrying amount of the developer. The layer thickness regulating means for regulating the amount of the developer adhering to the body surface has a detecting means for detecting the displacement of the layer thickness regulating means. The detecting means for detecting the distance between the developer carrier and the layer thickness regulating means include a pressure detecting means, a position detecting means, and a speed detecting means.

Further, it has an arithmetic means for analyzing the detection signal and giving a control signal to the control means and a memory, and a drive means for controlling the layer thickness regulating means and the behavior of the developer carrier, the above-mentioned carrying amount, and the adhering amount. .

[0011]

By providing a means for detecting the distance between the developer carrying member and the layer thickness regulating means, the layer thickness of the developer can be controlled to be constant.

The detecting means includes a means for detecting a pressure, a means for detecting a position, and a means for detecting a speed. The detecting signal is analyzed by using a calculating means and a memory, and a control signal is given to a driving means to obtain a layer thickness. It regulates the behavior of the regulating means and the developer carrier.

By providing the layer thickness regulating means with the movement driving means, it is possible to change the adhesion amount of the developer which passes through the layer thickness regulating means and can be used for development. For example, when the layer thickness regulating member is pressed in the direction perpendicular to the surface of the developer carrying member, the layer thickness becomes thin. Further, the larger the curvature of the layer thickness regulating means at the contact position between the developer carrying member and the layer thickness regulating means, the thicker the layer thickness. As described above, by providing the movement driving means and the detecting means in the layer thickness regulating means, the developer layer thickness can be controlled, and a stable printed image without unevenness can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, an electrophotographic image forming apparatus has a developing device for supplying a developer 1 to an electric latent image. The developer 1 is supplied from a developer container 2 of a developing device to a developing roll (developing sleeve) which is a developer carrier 5 by a developer transporting means such as a stirring roll 3 and a transporting roll 4. The developer 1 attached on the developing roll is regulated by the developer layer thickness regulating means 6 so that the layer thickness of the developer 1 is about 1 to 3 layers. The developer 1 having a desired layer thickness is developed according to the electric latent image on the surface 7 of the photoconductor.

In the developing device, it is most important to stably supply the developer, and in order to stabilize the amount of the developer 1 supplied from between the developer carrier 5 and the layer thickness regulating means 6. , The distance between them must be constant.

In the structure in which the layer thickness regulating means 6 is pressed against the developer carrying body 5 by the elastic member 9, when the developing device is driven at high speed, the developer is held between the developer carrying body 5 and the layer thickness regulating means 6. A large amount of 1 flows in, the gap between the two widens, and the supply of the developer becomes excessive. Further, the gap between the latent image carrier and the developer carrier, and the distance between the developer carrier and the layer thickness control means changes due to the inflow amount of the developer, and the vibration occurs. As a result, there is a problem in that density unevenness occurs in the printed image. In particular Figure 6
The left and right edges are likely to have unevenness, and may have a black and white striped pattern. As described above, during high-speed operation of the developing device,
Since it is difficult to keep the layer thickness of the developer constant, it is necessary to control the gap between the developer carrier 5 and the layer thickness regulating means 6 to be constant.

An embodiment of the present invention will be described below with reference to FIG.

In the present invention, the moving means for displacing the layer thickness regulating means and the driving means for applying pressure are provided. Conventionally, the load applied to the contact point with the developing roll and the contact position of the layer thickness regulating member are fixed and used. By newly providing the layer thickness regulating means with the driving means, it is possible to change the adhesion amount of the developer which has passed through the layer thickness regulating means and can be used for development.

A moving means for displacing the layer thickness regulating member in a direction perpendicular to the surface of the developer carrying member or a driving means for urging is provided, and when displaced and pressed, the layer thickness becomes thin as shown in FIG. Variations in layer thickness are small. That is, even if a flat plate is pressed, if it is pressed strongly, the layer thickness becomes thin. It may be moved and driven in an oblique direction other than the vertical direction. The moving means and the driving means are referred to as moving driving means in consideration of the operation of pressing when the member cannot move.

A member having a curvature is used for the layer thickness regulating means, and a moving drive means for changing the contact position between the developer carrying member and the layer thickness regulating means is provided. The larger the curvature of the layer thickness regulating means is, the thicker the layer becomes as shown in FIG. That is, the more sharp the corner of the layer thickness regulating means is at the contact position, the more the developer cannot pass. If the corners of the layer thickness regulating means are smooth like a flat surface, the developer can easily pass through. That is, the curvature of the contact position can be changed by moving or rotating the layer thickness regulating member having a curvature in the moving direction of the developer carrying member, and the amount of developer adhered can be changed. .

In order to obtain an appropriate toner (developer) layer thickness on the surface of the developing roll (developer carrier), the layer thickness is regulated according to the driving speed of the developing device, particularly according to the speed of the developing roll surface. It must be made. Also, the deformation that occurs when the developing roll is stopped must be prevented.

In the present invention, when the developing roll is stopped, the pressing load of the layer thickness regulating blade (layer thickness regulating member) on the developing roll is reduced, and when the developing roll is driven, the pressing load is controlled by the speed. Try to increase. The change in the load increases continuously or in multiple steps and then decreases. When the target speed is reached,
Make sure that an appropriate pressing load and contact position are obtained.

As another embodiment, there is a method of applying an appropriate pressing load at the target speed when the developing roller is driven when the target speed is one. In this method, the load may be set in two steps, and a simple structure can be used.

As another embodiment, there is a method in which the pressing load is kept the same as when the developing roll is stopped in the low speed rotation region where the developing roll starts to be driven. With this method, the load during rotation from stop to low speed rotation can be reduced, and initial rotation can be performed smoothly. The movement driving means 8 for changing the layer thickness in the present invention includes the following.

When a piezoelectric element is used, a displacement can be created by applying an arbitrary electric potential, and the pressure applied to the developing roll or the contact position can be changed by the displacement. Using this means, it can be made very small. In addition, a bimetal and a heat source may be used.

When the cam mechanism is provided in the layer thickness regulating means by an eccentric roll or a disc, the pressing pressure to the developing roll or the contact position can be changed. If this means is used, only the rotation of the cam can be performed, so that it can be driven easily.

When an electromagnet is used, a large displacement can be obtained instantly.

As another embodiment, by using or adding an elastic body to the layer thickness regulating means, vibration generated in the layer thickness regulating member can be alleviated. For example, a spring (spring spring 11, leaf spring, etc.), rubber 9, foam or the like is arranged on the back surface of the layer thickness regulating blade (member). For example, an elastic body may be arranged on the surface of the movement driving means as shown in FIGS.

In another embodiment, a tube in which a gas such as air is injected is used as the elastic body. In this case, the elasticity (rigidity) of the tube can be changed by changing the gas pressure using the gas pressure varying means, and the pressing pressure can also be changed. For example, by increasing the gas pressure, the rigidity of the tube is increased, and the layer thickness regulating member is less likely to vibrate. Further, the swelling of the tube can change the pressure applied to the developing roll or the contact position.

The layer thickness regulating member at the contact position between the developing roll and the layer thickness regulating means is made of a metal which has been conventionally used,
In addition to plastic, rubber, ceramic, etc., the surface of the movement driving means such as a piezoelectric element or auxiliary means may be used as it is.

In the present invention, the layer thickness regulating means is provided with means for detecting the displacement. Particularly, a means for detecting the displacement in the direction perpendicular to the surface of the developer carrier is best provided.

As means for detecting displacement, there are means for detecting the position of the layer thickness regulating member and means for detecting pressure. As means for detecting the position, in addition to a distance sensor such as an optical type and an ultrasonic type, a switch element that switches at a predetermined position or more and a solenoid that detects by electromagnetic induction are used to detect the position.

The optical and ultrasonic distance sensors mainly measure the distance from the inner frame of the developing device to the layer thickness regulating member and detect the position of the layer thickness regulating member. However, there are cases in which other parts, such as the elongation of the elastic body, are measured.

The switch element switches when expansion or contraction of a predetermined amount or more occurs, so that it can be maintained within a predetermined range. This switch element is simply used in two-value or three-value, but may be a multi-point switch.

The solenoid is fixed to an elastic member and the like together with the magnet, and detects the electromagnetic induction current corresponding to expansion and contraction of the elastic member.

Further, as the means for detecting the pressure, a pressure sensor or the like is used in addition to the piezoelectric element to detect the pressure. The change in layer thickness can be known from these changes in pressure.

Since the piezoelectric element generates a voltage by pressure, when a displacement occurs, a voltage corresponding to the displacement is applied,
The vibration of the layer thickness regulating member can be detected.

As another embodiment, the developer carrying member is provided with a means for detecting its rotational speed. The means for detecting the speed detects the surface speed of the developer layer thickness regulating means and the developer carrier by detecting the output of a tachometer of a rotating body such as a layer thickness regulating roll or a developing roll or detecting a motor current.

The above-mentioned movement driving means, elastic member, detecting means, and layer thickness regulating member may be combined in multiple layers as shown in FIGS. As shown in FIG. 4, an elastic member 9 such as rubber is arranged on the movement driving means 8, a detecting means 10 such as a piezoelectric element is arranged thereon, and a layer thickness regulating member 6 is arranged thereon. The arrangement of means other than the thickness regulating member may be changed. FIG. 5 shows a spring 11 as an elastic member,
An example of using the switch element 12 as the detection means will be described.

The detecting means is composed of one or more. When the number of detecting means is one, it is usually arranged in the central portion of the developer layer thickness regulating means or the developer carrier. When it is mainly desired to detect vibration or when it is difficult to attach the vibration, it may be arranged at the end of the regulation means or the carrier. Further, if a long detecting means such as a piezoelectric element is used, it becomes possible to detect the regulating means and both ends of the carrier at once. When there are a plurality of detecting means, they may be appropriately arranged at the central portion and the end portions as described above. For example, by arranging one at each end, the displacement at the central portion can be estimated. Further, even when the central portion and the one end are arranged, the displacement of the other end can be estimated, and the displacement of the regulating means and the carrier can be known.

The above detection output signal is analyzed as follows.

When a switch element is used as the detecting means, the output signal is on / off. When the switch elements are combined, each switch element turns on / off. When the signal of the switch element changes when the developing device is driven, it can be determined that a stable developer layer thickness cannot be supplied. For example, when the gap is widened and the switch is turned on, it is determined that the gap is widened. When the switch elements are combined, it is possible to digitally determine at which position the regulating means or the carrier is located.

When an element other than the switch element is used as the detecting means, the output signal becomes an analog output. The displacement from the proper output value can be detected to know the displacement of the regulating means and the carrier. Proper output values have different values depending on the element type and individual difference. Therefore, the appropriate output value may be different from the value that is initially set uniformly.
The proper output value may be based on the output value at that time when the positions of the regulating means and the carrier are proper. In addition, the average value of the output when the developing device is driven is sometimes used as a reference. In addition, the reference value may be determined by calculating from the maximum value, the minimum value, and the median value.

The displacement of the regulating means and the carrier is not limited to the instantaneous difference from the proper output value, but also the maximum value, the minimum value, the difference between the maximum value and the minimum value, the effective value, the average value, the integrated value, etc. It can be known by detecting and calculating one or more of the above. For example, maximum value, minimum value, difference between maximum value and minimum value,
It is possible to know the vibration of the regulating means and the carrier from the effective value, and the strain from the average value and integrated value.

The distortion information from the average value, integrated value, etc. is
It shows the amount of developer adhering to the developing roll at present, and it can be seen that the greater the strain, the greater the deviation from the proper developer layer thickness.

Next, a method of calculating the detected signal information will be described.

Information is roughly classified into two types. One is vibration information and the other is distortion information. Since vibration does not occur in the developing device and stable driving without distortion must be performed, it is necessary to perform control to reduce vibration and eliminate distortion.

The vibration information is analyzed from the AC component of the detection signal information. As the maximum value of the AC component increases, the minimum value decreases, the difference between the maximum value and the minimum value increases, and the effective value of the AC component increases, vibrations occur. I have to

When the vibration becomes large, there is a method of increasing the load applied to the restricting means and the carrier, and weakening the vibration by holding the load. As another method, by providing the movement driving means in the pulling direction in addition to the movement driving means in the pushing direction, it becomes difficult to displace in both directions, and vibration can be suppressed. For example, control can be given to a pressing means such as a pressing spring located between the developer layer thickness regulating means and its supporting portion.

Control can be periodically given in advance by analyzing the low frequency component in the alternating current component of the detection information. For example, when vibration occurs due to the eccentricity of the developing roll or the surface state each time the developing roll makes one revolution, a uniform developer layer thickness can be obtained by controlling the displacement of the opposite phase corresponding to the vibration.

As described above, a more uniform developer layer thickness can be obtained by adding the information of various detecting means to the control given to the layer thickness regulating means at the time of accelerating and decelerating the developing roll.

Based on the result of the calculation using the detecting means as described above, the vibration of the layer thickness regulating means is first suppressed, and then the layer thickness is controlled to an appropriate amount. These controls may be performed simultaneously. Even with these controls, when it is calculated that the developer layer thickness is not stable, it may be handled as follows.

In some cases, the rotation speed of the rotating body such as the developing roll may be changed from the output signal 13 of various detecting means. For example, if the vibration resonates with the natural vibration of surrounding members at a certain rotation speed, the vibration cannot be suppressed by the layer thickness regulation control. Therefore, based on the calculation result of the arithmetic unit 14, in addition to the control signal 15 for the movement driving means, the control signal 17 for the developing roll driving unit 16 is given to change the rotation speed and prevent resonance.

Control can be given to each movement driving means inside the developing device from information of various detecting means. Further, the drive can be independently applied.

[0055]

According to the present invention, the layer thickness of the developer can be changed by providing the layer thickness regulating means with the movement driving means, and the development after the layer thickness regulation can be performed even if the developing device is operated at a high speed. The amount of developer deposited on the roll can be stably obtained,
It is possible to prevent uneven printed image density.

Further, the displacement of the layer thickness regulating means can be detected by the sensor provided in the layer thickness regulating means, and the displacement can be removed.

Further, it is possible to prevent the vibration due to resonance by changing the rotation speed of the developing roll.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a pressing pressure of a layer thickness regulating member and a developer layer thickness.

FIG. 3 is a characteristic diagram showing the relationship between the curvature of the layer thickness regulating member and the developer layer thickness at the contact position between the developer carrier and the layer thickness regulating member.

FIG. 4 is an explanatory diagram around a layer thickness control unit according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram around a layer thickness regulating means according to another embodiment of the present invention.

FIG. 6 is an explanatory diagram showing an example of image density unevenness.

[Explanation of symbols]

1 ... Developer, 2 ... Developer container, 3 ... Stirring roll, 4 ... Conveying roll, 5 ... Developer carrier, 6 ... Layer thickness regulating means, 7 ...
Image carrier (photoreceptor), 8 ... Movement driving means, 9 ... Elastic member (rubber), 10 ... Sensing means (piezoelectric element), 11 ... Elastic member (spring), 12 ... Sensing means (switch element), 13 ...
Detecting means output signal, 14 ... Arithmetic device, 15 ... Movement driving means control signal, 16 ... Developing roll driving device, 17 ... Developer carrier driving signal.

Claims (22)

[Claims] 1. A dry-type developer is attached to the surface of a developer-carrying member to form a developer layer on the developer-carrying member, and a developer is provided with a layer thickness regulating means for limiting the amount of the adhered layer. In a developing device of a dry electrophotographic image forming apparatus in which a developer whose amount is limited is used for development, a movement driving means for pressing or displacing the layer thickness regulating means with respect to the surface of the developer carrying member is provided. A developing device having. 2. The layer thickness regulating member according to claim 1, wherein the layer thickness regulating member has a curvature in a rotation direction of the developer carrier, and the layer thickness regulating member is in a contact position of the layer thickness regulating member with respect to the developer carrier. A developing device provided with a movement drive means so that the curvature of the contact position of the member changes. 3. The developing device according to claim 1, wherein the output of the movement driving means changes according to the speed of the developer carrying member. 4. The developing device according to claim 1, wherein the output of the movement driving means continuously changes according to the speed of the developer carrying member. 5. The developing device according to claim 3, wherein the output of the movement driving unit changes after the rotation start of the developer carrier. 6. The method according to claim 1, 2, 3, 4 or 5.
A developing device using a piezoelectric element as the movement driving means. 7. The method according to claim 1, 2, 3, 4 or 5,
A developing device using an eccentric cam mechanism for the movement driving means. 8. The method according to claim 1, 2, 3, 4 or 5.
A developing device using an electromagnet for the movement driving means. 9. The method according to claim 1, 2, 3, 4 or 5.
A developing device using a bimetal for the movement driving means. 10. A developing device according to claim 1, 2, 3, 4 or 5, wherein a tube and a gas pressure varying means are used as the movement driving means. 11. Claims 1, 2, 3, 4, 5, 6, 7,
8. A developing device according to 8, 9, or 10, further comprising position detecting means of the layer thickness regulating means, and arithmetic means for giving control to the movement driving means from the output of the detecting means. 12. The developing device according to claim 11, wherein an optical distance sensor is used as the position detecting means. 13. The developing device according to claim 11, wherein an ultrasonic distance sensor is used as the position detecting means. 14. The developing device according to claim 11, wherein a mechanical switch is used as the position detecting means. 15. The developing device according to claim 11, wherein a solenoid is used as the position detecting means. 16. Claims 1, 2, 3, 4, 5, 6, 7,
8. A developing device according to 8, 9, or 10, including pressure detecting means of the layer thickness regulating means, and arithmetic means for giving control to the movement driving means from the output of the detecting means. 17. The developing device according to claim 16, wherein a piezoelectric element is used as the pressure detecting means. 18. The developing device according to claim 16, wherein an atmospheric pressure sensor is used as the pressure detecting means. 19. Claims 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 12, 13, 14, 15, 16,
17. A developing device according to 17 or 18, comprising a rotational speed detecting means for the developer bearing member or the rotating body of the layer thickness regulating means, and an arithmetic means for giving control to the movement driving means from the output of the detecting means. 20. The developing device according to claim 19, wherein a speedometer is used as the rotation speed detecting means. 21. The developing device according to claim 19, wherein the rotation speed detecting means includes means for detecting a motor current. 22. Claims 11, 12, 13, 14, 15,
16. A developing device, comprising 16, 17, 18, 19, 20 or 21, an arithmetic means for giving control to the drive means of the developer carrier from the output of the detection means.