JP2001066873A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately calibrate a toner concentration sensor by providing a reference body measured as substance showing specified toner concentration by a concentration sensor movable to a measuring position at a specified timing. SOLUTION: This device is equipped with the reflection type concentration sensor 40 optically measuring the toner concentration on a developing roll 12 and the reference body 50 measured by the sensor 40 as substance having reflectance equivalent to the specified toner concentration. The reference body 50 reaches the measuring position 22 opposed to the sensor 40 at a home position. Then, the reference body 50 is measured at the position 22 by the sensor 40. At such a time, the surface of the reference body 50 exists on circular orbit 20, and measuring distances and the like are equal to each other when the measuring condition of the surface of the reference body 50 is compared with the measuring condition of the toner concentration on the roll 12. Namely, the reference body 50 is measured under the ideal measuring condition as the measuring condition of constitution reference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for developing an electrostatic latent image with toner, which is incorporated in an image forming apparatus used in an electrophotographic copying machine or printer.
In particular, the present invention relates to a developing device that sequentially moves a plurality of developing units storing toners of different colors from each other via a predetermined developing position.

[0002]

2. Description of the Related Art Conventionally, in a developing device incorporated in an image forming apparatus used for an electrophotographic copying machine or a printer, a two-component developer toner composed of a carrier and a toner carried on a developing roll is used. 2. Description of the Related Art A developing device that measures the density with an optical toner density sensor and controls toner supply based on the measurement result is known. As a toner density sensor, a method of measuring reflected light from a developer using a light emitting element (LED) and a light receiving element is widely used. However, the sensitivity of the toner density sensor is changed over time due to toner contamination or other causes. Change. Therefore, the sensor sensitivity must be calibrated, but an inexpensive developing device capable of calibrating the sensor sensitivity has not been realized yet.

[0003]

For example, Japanese Patent Application Laid-Open No.
Japanese Patent Application Laid-Open No. 349480 discloses a technique for non-contactly measuring the toner density on a developing roll at a position outside a developing position in a rotary developing device that sequentially rotates and moves a plurality of developing units. Further, Japanese Patent Application Laid-Open No. 05-31
Japanese Patent No. 3495 discloses, for the purpose of offset compensation based on LED temperature characteristics, the amount of light reflected directly from the surface of a developing roll where no developer is present and the amount of reflected light detected from the developer conveyed on the developing roll. A technique for detecting the toner density by calculating the ratio of the toner is disclosed. This technology is LE
The purpose is to compensate for the variation over time of the light amount of D,
As a compensation standard, a developing roll surface having a high specular reflection component is used. However, the diffuse reflectance of the surface of the developing roll is extremely unstable due to a large variation with time due to repeated development steps and a large variation in the reflection state due to a difference in position on the surface. For this reason, if the development roll surface is used as a compensation standard, sensitivity calibration cannot be performed with high accuracy,
It is not possible to calibrate the mounting accuracy and sensitivity variation of the toner density sensor.

Further, a technique using a monitoring LED having a built-in reflector as a compensation standard has been proposed, but the structure of the sensor is complicated and the size of the apparatus is increased.

In view of the above circumstances, an object of the present invention is to provide an inexpensive developing device capable of calibrating a toner density sensor with high accuracy.

[0006]

According to a first aspect of the present invention, there is provided a developing device for storing a toner therein, wherein the housing transports the toner inside the housing to the outside of the housing, and a part of the housing is exposed from the housing. And a plurality of developing units storing toners of different colors from each other, the plurality of developing units integrally, the developing roll of the plurality of developing units, The portion exposed from the housing follows a predetermined trajectory passing through a developing position close to or in contact with an image carrier on which an electrostatic latent image is formed on the surface, and the developing rolls of the plurality of developing units are sequentially moved to the developing position. By moving the developing roller to reach the developing position, the developing roller arrives at the developing position and develops the electrostatic latent image on the surface of the image carrier with the toner conveyed. A density sensor for measuring the toner density on the developing roll of the developing unit that has reached a predetermined measuring position on the predetermined track, of the plurality of developing units, and moves to the measuring position at a predetermined timing; A reference body measured by the density sensor to indicate a predetermined toner density.

According to a second aspect of the present invention, there is provided a developing device comprising: a housing for storing toner therein; and a developing roll for conveying toner inside the housing to the outside of the housing, the developing roll being partially exposed from the housing. A plurality of developing units storing toners of different colors from each other, and the plurality of developing units are integrally formed, and the developing rolls of the plurality of developing units are exposed from the housing. The portion follows a predetermined trajectory via a developing position close to or in contact with the image carrier on which an electrostatic latent image is formed on the surface, and the developing rolls of the plurality of developing units sequentially reach the developing position. By moving the developing roller to reach the developing position, the developing roller develops the electrostatic latent image on the surface of the image carrier with the toner conveyed. A density sensor for measuring the toner density on the developing rolls of the developing units whose developing rolls have reached a predetermined measurement position on the predetermined track among the number of developing units; and a measuring window on the front surface of the density sensor for covering the density sensors. Opened cover, also served as a reference body measured by a density sensor as indicating a predetermined toner density,
A shutter for closing the measurement window of the cover at a predetermined timing.

[0008]

Embodiments of the present invention will be described below.

FIG. 1 is a view showing a first embodiment of the developing device of the present invention.

The developing device 1 includes a housing 11 in which toner is stored, and a toner which is partially exposed from the housing 11 and is inside the housing 11.
And four developing units each including a developing roll 12 to be transported to the outside.
C, 10M, 10Y, and 10K store cyan (C), magenta (M), yellow (Y), and black (K) toners, respectively. These four developing units 10C, 10M, 10Y, and 10K are located at developing positions 21 close to or in contact with the photosensitive roll 2, which is an example of an image carrier according to the present invention on which an electrostatic latent image is formed.
Is rotated integrally with the developing roller 12 in the direction of the arrow F1 around the rotating shaft 30 shown in the drawing so that the portion exposed from the housing 11 of the developing roll 12 follows. Then, the electrostatic latent image on the photosensitive roll 2 is developed by the toner on the developing roll 12 of each of the developing units 10C, 10M, 10Y, and 10K that has reached the developing position 21. The moving order of the developing units 10C, 10M, 10Y, and 10K is in the order of KYMC, and this order is an order selected based on the color developing property and transfer property of the toner.

Each of the developing units 1 during non-development
0C, 10M, 10Y, and 10K are stopped in such an arrangement that the photosensitive roll 2 faces the middle between the cyan (C) developing unit 10C and the black (K) developing unit 10K. Such an arrangement is called a home position,
In order to shorten the time until the first print is obtained when the development is resumed, black (K)
Is arranged so that the developing unit 10K can quickly face the photosensitive roll 2.

As a method for moving the developing unit, a rotary method for rotating and a sliding method for linearly moving can be considered.
One or less or five or more numbers are conceivable, but here, an example of a developing device employing four developing units and a rotary type will be described.

The developing device 1 shown in FIG. 1 has a reflection type for optically measuring the toner density on the developing roll 12 which has moved to a measuring position 22 different from the developing position 21 by 180 ° on the circular orbit 20. A density sensor 40 and a reference body 50 having a reflectance corresponding to a predetermined toner density and measured by the density sensor 40 are provided. The density sensor 40 may be any one of a specular reflection type, a diffuse reflection type, and a common type. The reference body 50 is made of ceramic or resin containing a coloring material. Also, this reference body 50
Is attached to the magenta (M) developing unit 10M via a bracket 51, and reaches the measurement position 22 facing the density sensor 40 at the home position. Such a reference body 50 can be provided at low cost. Further, since the density sensor 40 is compensated based on the measurement result of the reference body 50, the density sensor 40 is compensated with high accuracy. The surface of the reference body 50 is
This is a curved surface having the same curvature as the curvature of the surface, whereby the reference body 50 is measured under the same measurement conditions as those for measuring the toner density on the developing roll 12.

Further, the developing device 1 is provided with a cleaning brush 60 for cleaning the reference member 50, which is an example of the cleaning device according to the present invention. For this reason, the change with time of the reflectance of the reference body 50 can be significantly suppressed, and the density sensor 40
Can be stably calibrated over a long period of time.

As will be described in detail below, the reference body 50 passes through the measurement position 22 and avoids the development position 21 while the plurality of development units 10C, 10M, 10
It moves with Y and 10K. FIG. 1 shows a state in which the reference body 50 is retracted into the circular orbit 20 to avoid the developing position 21.

FIG. 2 is a view showing a state in which the reference body 50 has reached a position opposing the cleaning brush 60.

Each of the developing units 10C, 10M, 10Y,
100K from the time when 10K reaches home position
ms, the reference body 50 has the cleaning brush 60
Has been reached. Then, at this time, the reference body 50 and the cleaning brush 60 move on the circular orbit 20 so as to press each other. As a result, the surface of the reference body 50 is rubbed and cleaned by the cleaning brush 60.

FIG. 3 is a diagram showing a state where each developing unit has reached the home position.

As described above, the reference body 50 reaches the measurement position 22 facing the density sensor 40 at the home position. Then, at this measurement position 22, the reference body 50 is measured by the density sensor 40. At this time,
The surface of the reference body 50 exists on the circular orbit 20. When the measurement conditions of the surface of the reference body 50 and the measurement conditions of the toner density on the developing roll are compared, the measurement distance and the like are equal to each other. That is, the reference body 50 is measured under ideal measurement conditions as the measurement conditions of the configuration standard.

FIG. 4 is a view showing a state immediately after the resumption of development.

The reference member 50 is moved to the circular orbit 20 immediately after the development is resumed.
Evacuate inside. On the other hand, the cleaning brush 60 is
With the developing unit 1 retreating to the outside of the circular orbit 20
Avoid contact with 0C, 10M, 10Y, 10K.

FIG. 5 is a diagram showing a state in which a certain developing unit has reached a measurement position.

FIG. 5 shows a state in which the magenta developing unit 10M has reached the measuring position 22 as an example.

Each of the developing units 10C, 10M, 10Y,
When 10K reaches the measurement position, the density sensor 40 measures the toner density on the developing roll 12. The measurement result is compared with the measurement result of the reference body 50, whereby an accurate toner density is obtained.

The description of the first embodiment has been completed, and the second and third embodiments will be described below. In the first embodiment, the reference body moves on a trajectory substantially similar to the predetermined trajectory together with the developing unit moving on the predetermined trajectory, whereas in the second and third embodiments, the reference body is Move via a predetermined retreat position and a measurement position outside the predetermined track.

FIG. 6 is a diagram showing a second embodiment of the present invention.

In the second embodiment, as in the first embodiment, the developing unit 10 rotates and the surface of the developing roll 12 moves on a circular orbit 20. Then, the toner density on the surface of the developing roll 12 reaching the measurement position 22 facing the density sensor 40 is measured. When the developing unit 10 is in the vicinity of the measurement position 22, the reference body 50 is at the retreat position 5 where the surface of the developing roll 12 moves away from the circular orbit 20.
I am evacuated to 2.

FIG. 7 is a view showing a state at the time of non-development in the second embodiment.

At the time of non-development, each developing unit 10
The developing unit 10 is stopped in an arrangement such that the middle of the developing unit 10 faces the density sensor 40. At this time, the reference body 50
It moves to the measurement position 22 facing the density sensor 40 and is measured by the density sensor 40.

FIG. 8 is a diagram showing a third embodiment of the present invention.

The third embodiment is a slide-type developing device in which the developing unit 10 moves linearly. Similar to the second embodiment, a linear track 70 on which the surface of the developing roll 12 moves is used.
The density of the toner on the surface of the developing roller 12 reaching the predetermined measurement position 71 facing the density sensor 40 is measured by the density sensor 40. Also, as in the second embodiment,
When the developing unit 10 is located near the measurement position 71, the reference body 50 is retracted to a retract position 53 deviated from the linear track 70 on which the surface of the developing roll 12 moves.

FIG. 9 is a diagram showing a state at the time of non-development in the third embodiment.

As in the second embodiment, in the third embodiment,
At the time of non-development, each developing unit 10 is stopped in a position where the middle of the two developing units 10 faces the density sensor 40, and at this time, the reference body 50 moves to the measurement position 71 and Measured.

In the second and third embodiments, the reference body reciprocates between the retreat position and the measurement position, but the reference body according to the present invention passes through the retreat position and the measurement position. It may be one that circulates in a circular orbit.

FIG. 10 is a diagram showing a fourth embodiment of the present invention.

The developing device 3 of the fourth embodiment has a structure shown in FIG.
Are provided with four developing units, and these four developing units rotate. FIG. 10 shows a circular orbit 2 on which the surface of the developing roll 12 moves.
0 and a developing roller 12 of one of the four developing units are illustrated, and other developing units and housings are not shown.

The developing device 3 is provided with a density sensor 40 facing the central axis of the developing roll 12 and a protective cover 80 for covering the density sensor 40. The protective cover 80 is connected to the frame 10 of the developing device via a support plate 90.
It is attached to 0.

FIG. 11 is an enlarged view around the density sensor.

A measuring window 81 is opened in the protective cover 80, and the density sensor 40 measures the toner density on the surface of the developing roll 12 moved to the measuring position 22 facing the density sensor 40 from the measuring window 81. A shutter 110 which can be opened and closed in the direction of arrow F2 shown in the figure is provided on the front surface of the measurement window 81. This shutter 110 is used for measuring the toner density on the surface of the developing roll 12 by the density sensor 40. The window 81 is opened, and the measurement window 81 is closed at times other than the time of measurement. The protective cover 80 and the shutter 110 prevent toner contamination of the density sensor. Therefore, the change over time of the sensitivity of the density sensor is small.

The shutter 110 is made of a ceramic or resin containing a coloring material in the same manner as the reference body 50 shown in FIG. 1. When the measurement window 81 is closed, the density sensor detects a predetermined toner density. It is measured as a reference with a corresponding reflectance. As described above, the shutter 110 also serving as the reference body has high durability as the reference body. Therefore, the concentration sensor can be calibrated stably. Further, the shutter 110 also serving as the reference body can be provided at a low cost.

FIGS. 12 and 13 are views showing how the shutter 110 opens and closes, and shows how the protective cover 80 and the shutter 110 are viewed from the developing roll 12 shown in FIG. .

The shutter 110 has a narrow pattern portion 111.
And a wide plate portion 11 connected to one end of the handle portion 111.
FIG. 12 shows the plate portion 112 of the shutter 110.
Is blocking the measurement window. FIG.
3, a shutter 110 is provided on the plate portion 112 of the handle portion 111.
A state in which the measurement window 81 is opened by rotating around an end opposite to the connected end is shown.

[0043]

As described above, according to the developing apparatus of the present invention, the reference member which moves to the measurement position at a predetermined timing and which is measured by the density sensor to indicate the predetermined toner density, A shutter that doubles as
Since the density sensor is calibrated based on the measurement results of the reference body and the shutter, the density sensor can be calibrated with high accuracy.

Further, the reference member and the shutter can be provided at a low cost.

Further, since the shutter also serving as the reference body has high durability, the density sensor can be calibrated stably.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of a developing device of the present invention.

FIG. 2 is a diagram illustrating a state where a reference body has reached a position opposing a cleaning device.

FIG. 3 is a diagram illustrating a state where each developing unit has reached a home position.

FIG. 4 is a diagram showing a state immediately after resuming development.

FIG. 5 is a diagram illustrating a state in which a certain developing unit has reached a measurement position.

FIG. 6 is a diagram showing a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a state during non-development in a second embodiment.

FIG. 8 is a diagram showing a third embodiment of the present invention.

FIG. 9 is a diagram illustrating a state during non-development in a third embodiment.

FIG. 10 is a diagram showing a fourth embodiment of the present invention.

FIG. 11 is an enlarged view around a density sensor.

FIG. 12 is a diagram showing a state in which a measurement window is closed.

FIG. 13 is a diagram showing a state in which a measurement window is opened.

[Explanation of symbols]

1, 3 Developing device 2 Photosensitive roll 10, 10C, 10M, 10Y, 10K Developing unit 11 Housing 12 Developing roll 20 Circular orbit 21 Developing position 22 Measuring position 30 Rotation axis 40 Density sensor 50 Reference body 51 Bracket 52, 53 Retreat position 60 Cleaning brush 70 Linear trajectory 71 Measurement position 80 Protective cover 81 Measurement window 90 Support plate 100 Frame 110 Shutter 111 Handle portion 112 Plate portion

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kimito Omori 2274 Hongo, Ebina-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. (72) Inventor Hideki Kimura 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. In-house (72) Inventor Koji Morito 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. Ebina Office F-term (reference) 2H077 AD06 BA09 CA11 DA10 DB25 GA13

Claims (5)

[Claims] A housing for storing toner therein;
A developing unit for transporting the toner inside the housing to the outside of the housing, and a developing roll partially exposed from the housing, comprising a plurality of developing units storing toners of different colors from each other; The plurality of developing units are integrated, and the portions of the developing rolls of the plurality of developing units that are exposed from the housing pass through a developing position that is close to or in contact with an image carrier on which an electrostatic latent image is formed on the surface. By moving the developing rolls of the plurality of developing units so as to sequentially reach the developing position by following a predetermined trajectory, the toner carried by the developing rolls that have reached the developing position statically fixes the surface of the image carrier. In a developing device for developing an electro-latent image, a developing unit of the plurality of developing units, wherein the developing roll reaches a predetermined measurement position on the predetermined track. A density sensor that measures the toner density on the developing roll of the cartridge, and a reference body that moves to the measurement position at a predetermined timing and is measured by the density sensor to indicate a predetermined toner density. A developing device. 2. The developing device according to claim 1, wherein the reference body moves with the plurality of developing units while passing through the measuring position and avoiding the developing position. 3. The developing device according to claim 1, wherein the reference body moves via a predetermined retreat position outside the predetermined track and the measurement position. 4. The developing device according to claim 1, further comprising a cleaning device for cleaning said reference member. 5. A housing for storing toner therein,
A developing unit for transporting the toner inside the housing to the outside of the housing, and a developing roll partially exposed from the housing, comprising a plurality of developing units storing toners of different colors from each other; The plurality of developing units are integrated, and the portions of the developing rolls of the plurality of developing units that are exposed from the housing pass through a developing position that is close to or in contact with an image carrier on which an electrostatic latent image is formed on the surface. By moving the developing rolls of the plurality of developing units so as to sequentially reach the developing position by following a predetermined trajectory, the toner carried by the developing rolls that have reached the developing position statically fixes the surface of the image carrier. In a developing device for developing an electro-latent image, a developing unit of the plurality of developing units, wherein the developing roll reaches a predetermined measurement position on the predetermined track. A density sensor for measuring the toner density on the developing roll of the printer, a cover covering the density sensor and having a measurement window opened in front of the density sensor, and measuring with the density sensor to indicate a predetermined toner density And a shutter that also serves as a reference body to be closed and closes a measurement window of the cover at a predetermined timing.