JP2007271770A - Developing device and manufacturing method for developing device, and doctor gap measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a doctor gap measuring method by which the doctor gap is optically measured by arranging a light emitting element and a light receiving element on an optical line passing through a doctor gap, to provide a manufacturing method for a developing device for adjusting the position of a doctor on the basis of the result of such measurement, and to provide a developing device to use the manufacturing method. <P>SOLUTION: A developing roller 9 and the doctor 12 opposite to the developing roller are attached in a developing container. The developing container 4 has: a development opening 8 formed in the position where the development container faces a photosensitive roller 7; and a measurement opening 18 formed on an optical path connecting the doctor gap formed between the developing roller and the doctor, and the development opening 8. The doctor gap is optically measured. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a developing device incorporated in an image forming apparatus such as a copying machine, a printer, or a facsimile, and more particularly to a method of manufacturing a developing device that measures a doctor gap and adjusts and fixes a doctor based on the measurement result.

The image forming apparatus visualizes the electrostatic latent image formed on the surface of the photosensitive roller having photoconductivity with the developing toner conveyed by the developing roller. Since the developing toner can be easily colored, a two-component developer composed of toner and a magnetic carrier is widely used. The developer is agitated and mixed in the developing device and frictionally charged, and the electrostatic charge causes the toner to electrostatically adhere to the surface of the magnetic carrier. The magnetic carrier to which the toner is attached in this way is attracted by the magnetic force of the magnet to the surface of the developing sleeve having a plurality of magnets disposed therein, and is conveyed along with the rotation of the developing sleeve.
A main magnet is disposed inside the developing sleeve at a position where the developing sleeve is close to the photosensitive sleeve. The developer conveyed on the developing sleeve forms a magnetic brush along the magnetic field lines of the main magnet. This magnetic brush performs development by transferring toner to the electrostatic latent image of the photosensitive roller.
When the developer is transported by the developing sleeve, in order to adjust the amount of the developer transported to the developing area facing the photosensitive roller, a predetermined interval (hereinafter referred to as a doctor gap) is opened on the outer peripheral surface of the developing sleeve. Place. As described above, the doctor gap determines the amount of the developer and determines the image quality such as the print density and the resolution. Therefore, it is necessary to strictly adjust the doctor gap.
For this reason, Patent Document 1 discloses a technique for irradiating a doctor gap with parallel light from an incandescent lamp, a light emitting diode, and a laser element, and receiving the transmitted light with a light receiving element to detect the width of the doctor gap. .
Japanese Patent Laid-Open No. 1-273071

According to Patent Document 1, the doctor gap can be measured optically. However, the developer container generally contains a developer and has a substantially sealed structure so that the developer does not scatter. Therefore, the place where the light source for receiving the light for measuring the doctor gap and the light receiving element for receiving the light are arranged are limited. In Patent Document 1, a light emitting element and a light receiving element are arranged on a line that linearly connects a developer inlet, a doctor gap, and an opening where the developing roller and the photosensitive roller face each other.
Thus, the place where the light emitting element and the light receiving element are arranged is limited, and when the developer inlet, the doctor gap, and the opening where the developing roller and the photosensitive roller face each other cannot be linearly connected, Patent Document 1 The technology cannot be used.
In view of the above-described problems, the present invention provides a doctor gap measurement method capable of optically measuring a doctor gap by arranging a light emitting element and a light receiving element on a light beam passing through the doctor gap, and the measurement. The present invention provides a developing device manufacturing method that adjusts the position of a doctor based on the results, and a developing device that can be used in the manufacturing method.

The developing device according to the present invention includes a developing container, a developing roller attached in the developing container, a doctor attached in a position facing the developing roller, and a developing container formed in a portion where the developing container faces the photosensitive roller. An opening, a doctor gap formed between the developing roller and the doctor, and a measurement opening formed in a developing container on an optical path connecting the developing opening are provided. Thereby, the doctor gap can be measured optically.
In the present invention, a plurality of the measurement openings may be formed in the length direction of the doctor gap. Thereby, a doctor gap can be formed in parallel.
Further, in the present invention, a reflecting mirror is preferably arranged in the middle of the light beam. As a result, the measurement path can be formed at an arbitrary position by bending the optical path.

The doctor gap measuring method of the present invention includes a mounting step of attaching the developing roller and the doctor in the developing container, a doctor gap formed between the developing roller and the doctor, and a portion where the developing container faces the photosensitive roller. A measurement opening forming step for forming a measurement opening in a developing container on an optical path connecting the formed development openings, a measurement preparation step for arranging a light source at one end on the optical path, and a photoreceiver at the other end, And a measuring step of measuring the doctor gap based on the detection output of the light receiver. Thereby, the doctor gap can be measured optically.
In the present invention, a laser light source may be used as the light source, and laser light may be scanned in the width direction of the doctor gap. Thereby, the doctor gap can be measured with high accuracy.
In the present invention, the measurement step may be performed a plurality of times by rotating the developing roller. Thereby, the developing roller whose surface is knurled can also measure the doctor gap accurately.
Further, according to another aspect of the present invention, there is provided a developing device manufacturing method, wherein after the doctor gap is measured as described above, the adjustment step of adjusting the doctor gap based on the measurement result, and the adjustment A fixing step of fixing the doctor at the position, and a sealing step of sealing the measurement opening. Thus, according to the present invention, it is possible to obtain a developing device in which the doctor gap is adjusted with high accuracy.

  Since the developing device of the present invention includes the doctor gap formed by the developing roller and the doctor and the measurement opening formed in the developing container on the light beam connecting the developing opening, the doctor gap can be measured optically. Therefore, the absolute value of the doctor gap can be measured with high accuracy. Moreover, according to this invention, a doctor gap can be formed in parallel. Moreover, the measurement opening can be formed at an arbitrary position. Further, the developing roller whose surface is knurled can also measure the doctor gap accurately. As a result, according to the present invention, a high-speed and high-performance developing device can be realized.

FIG. 1 shows a cross-sectional view of the developing device of the present invention. In the developing device, a developing container 4 is formed by a lower case 1, an upper case 2, and a doctor cover 3. Furthermore, the doctor cover 3 includes a doctor mounting plate 5 and a cover 6. The developing container 4 has a developing opening 8 formed in a portion facing the photosensitive roller 7 having a photoconductor on the outer peripheral surface, a part of the developing opening 8 is exposed, and is separated from the photosensitive roller 7 by a developing gap. Then, the developing roller 9 is fixed to the upper case 2. By disposing the developing roller 9 apart from the developing gap in this way, the electrostatic latent image formed on the outer peripheral surface of the photosensitive roller is developed with the developer conveyed by the developing roller 9. The developing roller 9 has a structure in which a plurality of magnetic poles 10 arranged in a non-rotating radial direction inside and a cylindrical developing sleeve 11 made of a nonmagnetic material are arranged on the outer periphery thereof.
The doctor mounting plate 5 is formed of, for example, an extruded material of aluminum, and the inside thereof is hollow. Therefore, a cooling effect is obtained. A doctor 12 made of stainless steel, for example, is fixed to the doctor mounting plate 5 with screws 13 so that the position can be adjusted based on the measurement result of the present invention. The doctor 12 may be made of a nonmagnetic material such as an aluminum alloy or brass. The doctor cover 3 to which the doctor 12 is attached to the doctor attachment plate 5 and the cover 6 is further attached is assembled at a predetermined position of the lower case 3. A transport battle 14 and a stirring roller 15 are further attached to the rotating shafts 16 and 17 in the lower case 3. In addition, the developing device includes an opening for supplying toner, an agitator for stirring the toner, and a toner remaining amount sensor.

  In the present invention, the measurement opening 18 is formed in the lower case 1 on a straight line connecting the doctor gap A formed at the portion where the developing roller 9 and the doctor 12 face each other and the photosensitive roller facing opening 6. The measurement opening 18 is, for example, a circular opening having a diameter of about 5 to 2 mm, preferably 4 mm. Or it is a square or rectangular opening. A plurality of measurement openings 18 are formed in the length direction of the doctor gap A. For example, the doctor gap A is formed in the center in the length direction, three at the left end and the right end. Alternatively, two are formed on the left side and the right side. After the measurement is completed, the inner wall of the measurement opening 18 is screwed so that it can be sealed with the screw 19. Alternatively, a female screw is attached to the measurement opening 18.

  The developing device of the present invention is configured as described above. When measuring the doctor gap, first, the developing roller 7 is attached to the upper case 2. Further, the doctor attachment plate 5 having the doctor 12 attached thereto is attached to the lower case 3. Therefore, at this stage, the cover 6 is not attached and the screw 13 is exposed. The upper case 2 and the lower case 3 are combined and integrated. Further, the lower case 3 is in a state in which the conveyance battle 14 and the stirring roller 15 are not attached.

Thereafter, as shown in FIG. 2, the developing device is placed on a measuring table 23 in which the light emitting element 21 and the light receiving element 22 are arranged with an interval larger than the size of the developing device. At this time, the developing device is placed and temporarily fixed so that the straight line connecting the light emitting element 21 and the light receiving element 22 and the straight line connecting the developing opening 8, the doctor gap A, and the measuring opening 18 of the developing device coincide.
The optical measurement apparatus of the present invention uses a laser beam B emitted from a light emitting element 21 such as a laser element as shown in FIG. The laser beam B is irradiated onto the rotating polygon mirror 24, and the reflected light is scanned into a range of width C by the cylindrical lens 25. The laser beam B passes through the measurement aperture 18, the doctor gap A, and the development aperture 8. It reaches the light receiving element 22 through the lens 26. The angle of the polygon mirror 23, the irradiation direction of the laser beam B, and the refractive index of the lens 24 are determined so that the scanning width C of the light beam is scanned in a range larger than the width direction of the doctor gap A.

The optical measurement apparatus of the present invention scans the laser beam B in the width direction of the doctor gap, and measures the width of the doctor gap according to the period in which the light receiving element 22 receives light. FIG. 4A shows a scanning pulse of laser light, and FIG. 4B shows a light receiving pulse of the light receiving element. When the doctor gap is large, the light receiving period t of the light receiving element 22 is lengthened, and when the doctor gap is small, the light receiving period t of the light receiving element 22 is shortened. As described above, since the doctor gap is detected based on the phase difference between the light receiving period t and the light emission timing s of the light emitting element 21, the light receiving output can be digitally processed. Further, it is possible to detect how much the upper or lower side of the doctor gap is deformed by the light receiving period or the phase shift, and the doctor gap can be detected with higher accuracy. It can also be seen how much adjustment is required for the doctor or the developing roller forming the doctor gap. The doctor gap is adjusted in accordance with the specifications of the image forming apparatus or the developing apparatus, for example, 0.01 to 0.5 mm, preferably 0.1 to 0.2 mm.
The doctor gap is adjusted as described above. In the present invention, since a plurality of measurement openings 18 are formed, the doctor gap may be sequentially measured and adjusted for each measurement opening 18, but the light emitting element may be used for the plurality of measurement openings 18. The developing device is placed on the measuring table 23 so that the straight line connecting the light receiving element 22 and the straight line connecting each developing opening 8, the doctor gap A and the measuring opening 18 is aligned, and the doctor gap is measured and adjusted. This is preferable because the parallelism of the doctor gap can be adjusted.
In the above description, a laser beam is used. An incandescent lamp, a light emitting diode, and a laser element are used as a light source. A beam bundle wider than the doctor gap width is formed, and this is irradiated onto the doctor gap. It is also possible to detect the gap width.

Such an optical measurement is performed at the center, left end, and right end of the doctor gap. Alternatively, two points on the left side and the right side are measured. In this measurement, since the surface of the developing roller 9 may be provided with a grid-like or iris-like knurled groove (not shown), the developing roller 9 is rotated by 30 ° to 90 °, preferably 60 °. Multiple doctor gap measurements. The knurled groove has a groove depth of 5 to 30 μm, a groove width of 10 to 100 μm, and a knurled pitch of 50 to 500 μm. The knurled grooves serve to form a toner layer on the image roller 9, and when the layer is thinned by the doctor 12, the toner aggregates are loosened and spread uniformly on the surface of the developing roller 9. As a result, a good toner thin layer is formed on the surface of the developing roller 9, and a uniform toner image can be obtained during development.
Thus, by rotating the developing roller and measuring a plurality of times, the doctor gap can be measured at a place where the knurling is not performed. The position of the doctor 12 is adjusted based on the measurement results at the center, the left end, and the right end, or the left and right two positions, and the doctor 12 is fixed to the adjusted position with the screw 13. Thereby, it is possible to form a parallel doctor gap so as to eliminate the influence of the eccentricity of the developing roller 9 and improve the image quality such as image density and resolution.

  After adjusting the doctor gap A as described above, the screw 19 is screwed into the measurement opening 18 and sealed. Or you may seal by filling with resin or an adhesive agent and solidifying. The screw 19 or the resin or adhesive that seals the measurement opening 18 prevents unevenness on the inner wall of the developing container so as not to disturb the toner flow. Thereafter, the lower case 1 and the upper case 2 are separated, the transport battle 14, the stirring roller 15 and other parts are attached to the lower case 1, and the lower case 1, the upper case 2, and the cover 6 are combined again to complete the developing device. .

In another embodiment of the present invention, as shown in FIG. 5, a reflecting mirror 27 is disposed on a light beam connecting the doctor gap A, the developing opening 8, and the measuring opening 18. Thereby, the location where the measurement opening 18 is formed can be changed to a desired position. For example, as shown in FIG. 5, a support pillar 28 is set up at a position between the transport battle 14 and the stirring roller 15, a reflection mirror 27 is attached to the tip of the support pillar 28, and the optical path can be bent in the direction of the upper case 2. Since there are no parts in the upper case 2 before the developing device is assembled, it is easy to open the measurement opening 18a. The location and angle at which the reflection mirror 27 is installed are not limited to the above location, and may be installed at any position on the light beam. Moreover, you may install a reflective mirror in two or more places, and you may bend a light beam twice or more.
After measuring the doctor gap using the reflection mirror 27 and fixing the doctor 12 with the screw 13, the lower case 1 and the upper case 2 are separated, and the conveying roller 14, the stirring roller 15 and other parts are attached to the lower case 1. . At this time, the support column 28 and the reflection mirror 27 are accommodated inside the developer container, for example, in the vicinity of the developer partition plate 29 above the stirring roller 15. Then, the lower case 1 and the upper case 2 are combined again to complete the developing device.

A sectional view of a developing device is shown. An explanatory view of doctor gap measurement is shown. A surface drawing of the measuring table is shown. A waveform diagram of the measurement is shown. Sectional drawing of the image development apparatus of other embodiment is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower case 2 Upper case 3 Doctor cover 4 Developer container 5 Doctor mounting plate 7 Photosensitive roller 8 Developing opening 9 Developing roller 12 Doctor 13 Screw 18 Measuring opening 19 Screw 21 Light emitting element 22 Light receiving element 23 Measuring stand

Claims (7)

A developer container;
A developing roller mounted in the developing container;
A doctor attached at a position facing the developing roller;
A developing opening formed in a portion where the developing container faces the photosensitive roller;
A developing apparatus comprising: a doctor gap formed between the developing roller and a doctor; and a measurement opening formed in a developing container on an optical path connecting the developing openings.   The developing device according to claim 1, wherein a plurality of the measurement openings are formed in a length direction of the doctor gap.   The developing device according to claim 1, further comprising a reflecting mirror disposed in the middle of the light beam. An attaching process for attaching the developing roller and the doctor in the developing container;
A measurement opening forming step for forming a measurement opening in a developing container on an optical path connecting a doctor gap formed between the developing roller and the doctor and a developing opening formed in a portion where the developing container faces the photosensitive roller. When,
A measurement preparation step of arranging a light source at one end on the optical path and a light receiver at the other end;
A doctor gap measuring method comprising: a measuring step of measuring the doctor gap based on a detection output of the light receiver.   5. The doctor gap measuring method according to claim 4, wherein a laser light source is used as the light source, and laser light is scanned in the width direction of the doctor gap.   The doctor gap measuring method according to claim 4, wherein the measuring step measures a plurality of times by rotating the developing roller. After carrying out the measurement method according to any one of claims 4 to 6,
An adjustment step of adjusting the doctor gap based on the measurement result;
A fixing step of fixing the doctor in the adjusted position;
And a sealing process for sealing the measurement opening.

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