JP2662423B2 - Method and apparatus for measuring uneven discharge of corona discharger - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring discharge unevenness of a corona discharger used in an image forming apparatus such as a copying machine.

[Conventional technology]

For example, in an electrophotographic copying machine, a main charging corona discharger for charging a photosensitive drum, a transfer corona discharger for transferring a toner image on a photosensitive drum onto paper, and a corona discharger for cleaning. Various corona dischargers are used. The corona discharger has a shield case having a U-shaped cross section and a charge wire extending in the longitudinal direction of the shield case.

Hereinafter, a corona discharger for main charging will be described as an example. The charge wire of the main charging corona discharger is arranged in parallel with the photosensitive drum and at a predetermined interval. When a discharge voltage is applied between the charge wire and the photosensitive drum, a corona discharge occurs between the two, and the surface of the photosensitive drum is charged to a predetermined potential.

By the way, if dust adheres to the charge wire of the corona discharger, or if the wire is deteriorated,
When it is not uniformly charged on the drum and an image is formed, it appears as a so-called white streak of an image. Therefore, in the manufacturing stage of the copying machine, it is necessary to inspect whether or not dust is attached to the charge wire at the time of assembly.

As a conventional inspection method of this type, a method of actually outputting an image and observing and confirming the image is generally used. Also, as shown in JP-A-55-153963,
In some cases, a light source and a light receiving cell are arranged opposite to each other with a charge wire interposed therebetween. In this method, the light source and the light receiving cell are scanned along a charge wire, and based on a signal obtained by the scan, dust, dirt, and the like attached to the wire are determined.

[Problems to be solved by the invention]

However, the above-described image output method requires not only consumables such as a developer and paper, but also requires time for making a single copy for confirmation thereof, and also requires a dedicated inspection machine. It also requires time to replace the original.

Further, according to the method disclosed in the above publication, no actual discharge is performed, and only the diameter of the wire is checked. Normal,
The above-mentioned discharge unevenness is caused not only by contamination of the charge wire, but also by discharge burrs and burrs of a shield case accommodating the charge wire, which may cause white streaks of an image. is there. In the method described in the above publication, it is not possible to confirm discharge unevenness due to the failure of the shield case.

Therefore, a method of measuring the charging status on the drum using a surface potential sensor and measuring the discharge unevenness is conceivable, but this surface potential sensor has a wide potential detection range and cannot accurately detect the discharge unevenness. It is possible. This will be described in detail with reference to FIG. As shown in FIG.
If there is dirt 2 such as dust in a part of the surface, normal discharge does not occur in the part of the dirt 2. Therefore, in the potential distribution A of the photosensitive drum, the portion corresponding to the stain 2 should drop as shown by the broken line in the figure. However, in reality, the potential is slightly decreased due to the characteristics as shown by the solid line in the figure due to the influence of the discharge in the other adjacent region. This drop portion becomes a white streak of the above-mentioned image. However, since the surface potential sensor averages a wide area B indicated by a dashed line in FIG. Is not detected as abnormal.

The present invention has been made in view of such a point, and it is not necessary to display an image. Further, the present invention provides a method and an apparatus for measuring discharge unevenness of a corona discharger, which can accurately determine the quality of a single corona discharger in a short time. The purpose is to gain.

[Means for solving the problem]

Discharge unevenness measuring method of corona discharger according to the present invention,
A slit plate having a minute slit is arranged to face a charge wire of a corona discharger, a voltage is applied to the charge wire to generate a corona discharge, and the slit plate is scanned along the charge wire, and the slit is scanned. This is to directly or indirectly detect a leakage current obtained through a minute slit of the plate to determine discharge unevenness.

The corona discharger discharge unevenness measuring device according to claim 2, further comprising: a voltage application unit for applying a discharge voltage to the corona discharger; and a slit disposed opposite to a charge wire of the corona discharger. Plate, a sensor provided opposite to the corona discharge device with the slit plate interposed therebetween, moving means for moving the slit plate and the sensor along the charge wire, and determining means for determining uneven discharge. And

The slit plate has a minute slit, and the sensor detects a leakage current obtained through the minute slit during discharging. Further, the determination unit determines a discharge unevenness by detecting a voltage change rate from an output of the sensor.

Further, the discharge unevenness measuring device for a corona discharger according to claim 3, a voltage applying means for applying a discharge voltage to the corona discharger, and a slit plate provided facing the corona discharger, A drum provided opposite to the corona discharge device with the slit plate interposed therebetween, a drum rotating means for rotating the drum, a sensor for detecting a surface potential of the drum, and the slit plate and the sensor connected to the charge wire. And a determining means for determining the discharge unevenness.

The slit plate has a minute slit at a position facing the charge wire, and the moving means moves the minute slit and the sensor synchronously and in the same direction.
The sensor measures a surface potential of the drum charged by a leakage current from a minute slit of the slit plate, and the determination unit detects a voltage change rate from an output of the sensor to measure discharge unevenness.

[Action]

In the present invention, a corona discharge is generated in the charge wire, and the sensor and the minute slit are moved along the charge wire. Then, a corona current leaks through the minute slit. This leakage current is directly detected by the sensor, or is temporarily charged on the drum, and the surface potential due to the charging is detected to indirectly detect the leakage current, and the discharge unevenness is determined based on the rate of change. Since the sensor detects a leakage current obtained through a minute slit, even a small change in corona discharge can be detected sensitively,
Discharge unevenness, which is the cause of white streaks in an image, can be accurately detected.

Such a method and apparatus for measuring uneven discharge eliminates the need for consumables such as developer and paper by the conventional method, and detects the actual discharge state. Unevenness can also be detected.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First
1 to 3 show an embodiment of a discharge unevenness measuring apparatus obtained by applying the discharge unevenness measuring method of the present invention. FIG. 1 is a sectional front view of the apparatus, and FIG. FIG. 3 is a cross-sectional side view. In these figures, reference numeral 3 denotes a jig table on which various components are placed and fixed. A stay 4 is provided at a plurality of positions on the jig table 3.
The upper cover 5 is provided on the stay 4.

On the jig table 3, a support table 7 on which a corona discharger 6 (see a two-dot chain line in FIG. 1) is placed is provided. The support base 7 is slidable in the left and right directions in FIGS. 1 and 2 by a slide guide 8 provided below the support base. End support members 9a and 9b for supporting lateral walls of both ends of the corona discharger 6 are provided at both left and right ends of the support base 7, respectively. Further, the first of the support
At the right end in the figure, a contact member 10 for positioning the corona discharger 6 placed on the support base 7 in the left-right direction is provided. Further, a handle 11 for pulling out the support table 7 to the outside of the measuring device main body is fixed to the outside of the contact member 10.

A corona discharger 6 is provided near the left end of the support 7.
A voltage application terminal 12 for applying a voltage to the jig table 3 is fixed to a stay 13 attached to the jig base 3. The voltage application terminal 12 is connected to a power supply via a high voltage transformer 14 or the like. The power supply is housed in a power supply box 15 shown in FIG.

As is clear from FIG. 3, above the support table 7,
A slit plate 16 having a substantially L-shaped cross section is provided. A small slit 17 of, for example, about 2 mm × 5 mm is formed in a part of the slit plate 16. The position where the slit 17 is formed is such that when the corona discharger 6 is placed on the support 7, the charge wire 1 and the slit 17 face each other. A potential sensor 18 is provided so as to be surrounded by the slit plate 16.
Are also arranged at positions facing the charge wire 1. The potential sensor 18 is mounted on a sensor support member 19, and the sensor support member 19 is fixed to a slide member 21 slidable along a linear guide 20. The linear guide 20, as shown in FIGS.
And is formed to be longer than the support table 7 in parallel with the upper cover 5.
It is fixed to the bottom surface.

A moving wire 22 is fixed to the slide member 21, as is apparent from FIGS. Moving wire
22 is wound around a fixed pulley 23 fixed to the right end of the linear guide 20, and is wound around a drive pulley 25 attached to the tip of a motor 24 arranged on the opposite side to the fixed pulley 23. I have.

Thus, the rotation of the motor 24 causes the sensor
18 and the slit plate 16 along the linear guide 20 in FIG.
It is movable in the left-right direction in FIG. As is clear from FIG. 2, photo interrupters 26a and 26b are provided near both ends of the linear guide 20. On the other hand, the slide member 21 includes a light shielding member 2 that passes between the light emitting portion and the light receiving portion of the photo interrupters 26a and 26b.
7 (see FIGS. 2 and 3) is fixed so that the range of movement of the slide member 21 is determined.

Further, the discharge unevenness measuring apparatus is provided with a main switch 28 and a pilot lamp 29 as shown in FIG.
As shown in FIG. 2, the start switch 3 for driving the motor
0, and a light emitting diode 31 for displaying the result of determination of uneven discharge
a, 31b are provided. Further, as shown in FIG.
A limit switch 32 is provided on the right side of the device. Although not shown, the apparatus is entirely covered with a wall so that the corona discharge is not affected by wind or the like, and a lid is provided on the right side in FIG. When opened, the limit switch 32 operates to clear the operation.For example, the motor 24 is controlled so as not to be driven even when the start switch 30 is pressed, and the operation is initialized by the limit switch 32 when the lid is closed. Has become.

FIG. 4 is a functional block diagram for determining discharge unevenness based on the output of the potential sensor 18. In the drawings, the same reference numerals as those in FIGS. 1 to 3 denote the same components. 35 is a differentiating circuit for differentiating the output of the potential sensor 18, and 36 is a comparing and judging circuit for judging discharge unevenness based on the differentiated output. An output change rate setting circuit 37 sets an upper limit value and a lower limit value, ie, an output change rate, serving as a reference for discharge unevenness, and a circuit (timer) 38 sets a measurement range.
Each of these circuits is configured in a control board 39 (see FIG. 1) fixed on the upper cover 5.

Next, the operation of the measuring apparatus will be described while describing a method for measuring discharge unevenness according to one embodiment of the present invention.

Here, it is assumed that the main switch 28 is turned on first. First, the lid (not shown) on the side wall of the apparatus is opened, and the support 7 is pulled out of the apparatus main body by the handle 11. The corona discharger 6 to be measured is placed on the support 7 pulled out,
The right end is positioned by contacting the contact member 10, and both ends of the corona discharger 6 are fixed by both end support members 9a and 9b. As described above, the limit switch 32 is off when the lid is open, and for safety,
It is controlled so that it does not operate even if the start switch 30 is pressed.

Next, the support 7 on which the corona discharger 6 is mounted is set inside the mounting, and when the lid is closed, the limit switch 32 is turned on and the apparatus is initialized. That is, the light emitting diode 31a or 31b indicating the previous discharge unevenness determination result is turned off, and the slide member 21 returns to the initial position as shown in FIG.
When the start switch 30 is pressed, the motor 24 rotates, and the drive pulley 25 rotates. The rotation of the driving pulley 25 causes the slide member 21 to move along the linear guide 20 via the moving wire 22.

When the slide member 21 moves and the photo interrupter 26b is turned off, a high voltage is applied to the corona discharger 6 via the voltage application terminal 12.

With the movement of the slide member 21, the slit plate 16 and the potential sensor 18 move above the charge wire 1 of the corona discharger 6. At this time, a current value leaking from a slit 17 formed in the slit plate 16 is detected by a potential sensor 18. As described above, since the slit 17 is formed to have a size of about 2 mm × 5 mm, the current value leaking from the slit 17 is small, and therefore, the sensor output is sensitive to a slight change in corona discharge. I do.

The output of the sensor 18 is differentiated by a differentiating circuit 35 shown in FIG. An upper limit value and a lower limit value for the output of the differentiating circuit 35 are set by the output change rate setting circuit 37 in the comparison judging circuit 36, and how long the output of the differentiating circuit 35 is compared with is measured by the measuring range setting circuit 38. Is set by Therefore, in this comparison and judgment circuit 36, the differentiation circuit
It is determined whether the output of 35 is between the upper limit and the lower limit. If it is within this range, the green light emitting diode 31a is turned on, and if it is out of the range, the red light emitting diode 31b indicating that there is uneven discharge is turned on.

When the slide member 21 moves and the light shielding member 27 comes to the photointerrupter 26a on the left side of the figure (the state shown by the dashed line in FIG. 2), a signal is output from the photointerrupter 26a to the control unit, Based on this, the unit controls the motor 24 so that the rotation direction is opposite to the above. Thereby, the slide member 21
Moves in the opposite direction, that is, to the right in the figure. During this movement, the same measurement as described above is performed to detect discharge unevenness.

In this embodiment, there is no need to perform image output unlike the related art, and the man-hours of the production line can be reduced. Also,
There is no need for a dummy developing section or consumables such as toner, developer, and paper.

In this embodiment, the corona discharger 6 is directly discharged,
Since the discharge state is measured, it is possible to detect not only the charge wire but also the abnormality of the shield case.

Next, another discharge unevenness measuring apparatus to which the discharge unevenness measuring method of the present invention is applied will be described with reference to FIG.

In FIG. 5, reference numeral 50 denotes a corona discharger 6 to be measured;
This is a set jig that is mounted with its opening facing downward. The corona discharger 6 has a terminal 51 for applying a voltage.
Is provided. The terminal 51 is connected to the right end of the set jig 50 in the drawing, and is connected to a high-voltage power supply (not shown). A metal belt 52 as a slit plate is disposed below the set jig 50 along the corona discharger 6.
A minute slit 53 is provided in a part of the metal belt 52,
The slit 53 is formed at a position facing the charge wire 1 when the corona discharger 6 is set on the setting jig 50. Both ends of the metal belt 52 are wound around winding rollers 54a, 54b, and one of the winding rollers 5
A roller driving motor 55 is connected to 4a. The metal belt 52 is grounded by a wiring 56.

A chargeable drum 57 having a photosensitive layer (optical semiconductor) is disposed at a position facing the corona discharger 6 with the metal belt 52 interposed therebetween. In the drum 57, a drum shaft 57a at a left end in the figure is rotatably supported by a drum support member 58, and a drum shaft 57b at a right end is connected to a drum drive system via a gear 59 and the like.

A surface potential sensor 60 for detecting the potential of the surface of the drum 57 is disposed at a predetermined interval in the rotation direction of the drum from the position where the corona discharger 6 is set. The distance between the corona discharger 6 and the surface potential sensor 60 is set to be about the distance between the main charging corona discharger and the developing roller in an actual copying machine. The surface potential sensor
A moving wire 61 is fixed to 60. Moving wire 61
Is wound around a fixed pulley 62 and a driving pulley 63, and a pulley driving motor 64 is connected to the driving pulley 63. The slit between the surface potential sensor 60 and the metal belt 52
53 is positioned so as to have a predetermined positional relationship in the width direction of the drum. The two move in the left-right direction synchronously while maintaining the predetermined positional relationship.

The output of the surface potential sensor 60 is input into the control box 65. In the control box 65, a circuit similar to that shown in FIG. 4 is configured to determine the discharge unevenness and control the lighting of the light emitting diodes 66a and 66b.

Next, the operation of the apparatus shown in FIG. 5 will be described.

The corona discharger 6 to be measured is set on the setting jig 50, and a high voltage is applied via the voltage application terminal 51. As a result, corona discharge occurs, and the corona current is
A predetermined portion of the drum 57 is charged by leaking from the slit 53. When the discharge is stabilized, the roller driving motor 55 is operated to move the metal belt 52 rightward in the drawing. As a result, the slit 53 moves along the charge wire 1, and a streak-like charged area is formed on the drum 57. On the other hand, the surface potential sensor 60 also moves rightward in synchronization with the slit 53 of the metal belt 52 via the moving wire 61 by the rotation of the pulley drive motor 64. Therefore, the drum
If the drum 57 is rotated by the drive system, the charged state of the drum 57 charged by the leakage current can be detected by the surface potential sensor 60.

This is schematically shown in FIG. E indicated by a broken line in the figure
The part shows the charged part. Surface potential sensor 60
As described with reference to FIG. 7, the charge amount in a predetermined range (the range B indicated by a dashed line in FIG. 7) is averaged and output, but the charge is caused by the current leaking through the minute slit 53 as described above. The surface potential of the charged drum is detected.
Or read the rise sensitively. This sensor output is input to the differentiating circuit 35 shown in FIG. 4 in the same manner as in the previous embodiment, and the discharge unevenness is detected in the same manner as described above.

In such an embodiment, similarly to the embodiment shown in FIGS. 1 to 3, it is possible to read the charged state sensitively by the current leaking through the minute slit 53, and further, the drum is rotated. Therefore, the influence of discharge in other adjacent areas can be reduced, and discharge unevenness can be detected more sensitively.

In addition, since the drum is actually charged, the discharge unevenness can be measured in a state closer to the use condition, and accurate measurement can be performed. In addition, if a drum that meets the product specifications is used, there will be no difference due to the matching between the corona discharger and the drum, and it is possible to eliminate the inconvenience that the measurement result at the time of assembly in the manufacturing stage differs from the state in the shipping state it can.

In each of the above embodiments, the measurement is performed by providing one set of the slit and the potential sensor. However, the measurement may be performed by providing a plurality of sets of the slit and the potential sensor. In this way, measurement can be performed in a shorter time, and work efficiency is improved. Alternatively, the output of the potential sensor may be input to a time recorder, and the discharge unevenness may be determined based on the output of the time recorder.

〔The invention's effect〕

As described above, according to the present invention, a slit plate having a minute slit is arranged to face a charge wire of a corona discharger, and a leakage current obtained through the minute slit is directly or indirectly detected. Since the discharge unevenness is determined by the above method, even a slight change in the corona current can be detected sensitively, and the discharge unevenness which is the cause of the white streak of the image can be accurately detected.

In addition, consumables such as developer and paper by the conventional method become unnecessary, and since the actual discharge state is detected, not only the charge wire but also the discharge unevenness due to the failure of the shield case can be detected, and accurate measurement can be performed. There are effects that can be performed.

[Brief description of the drawings]

FIG. 1 is a sectional front view of a discharge unevenness measuring apparatus to which the method of the present invention is applied, FIG. 2 is a plan view thereof, FIG. 3 is a partial side view thereof, and FIG. FIG. 5 is an overall perspective view of another discharge unevenness measuring apparatus to which the discharge unevenness measuring method of the present invention is applied, FIG. 6 is a schematic diagram for explaining the operation thereof, and FIG. It is a figure for explaining a problem. DESCRIPTION OF SYMBOLS 1 ... Charge wire, 6 ... Corona discharger, 12 ... Voltage application terminal, 14 ... High voltage transformer, 15 ... Power supply unit, 16 ... Slit plate, 17 ... Slit, 18 ... Potential sensor, 20 …… Linear guide, 21 …… Slide member, 22…
... moving wire, 24 ... motor, 31a, 31b ... light emitting diode, 35 ... differential circuit, 36 ... comparison and judgment circuit, 37 ... output change rate setting circuit, 38 ... measuring range setting circuit, 52 ... Metal belt, 53 ... Slit, 55 ... Motor for roller drive, 57 ... Drum, 60 ... Surface potential sensor, 61 ... Movement wire, 64 ... Motor for pulley drive, 65 ... Control box, 66a, 66b …… a light emitting diode.

Claims (3)

(57) [Claims] 1. A method for measuring discharge unevenness of a corona discharger used in an image forming apparatus, comprising: a slit plate having fine slits movably provided; Are arranged facing each other, a voltage is applied to the corona discharger to generate a discharge, the slit plate is scanned along a charge wire of the corona discharger, and a leakage current obtained through a minute slit of the slit plate is provided. Characterized by directly or indirectly detecting the discharge unevenness, and determining the discharge unevenness based on the detection result. 2. An apparatus for measuring discharge unevenness of a corona discharger used in an image forming apparatus, comprising: voltage applying means for applying a discharge voltage to the corona discharger; A slit plate having a slit disposed so as to face a charge wire of the corona discharger; a slit plate provided to face the corona discharger with the slit plate interposed therebetween; and detecting a leakage current obtained through a minute slit of the slit plate. And a moving means for synchronously moving the slit plate and the sensor along the charge wire of the corona discharger; and a judging means for detecting a voltage change rate from an output of the sensor and judging discharge unevenness. And a discharge unevenness measuring device for a corona discharger. 3. An apparatus for measuring discharge unevenness of a corona discharger used in an image forming apparatus, comprising: a voltage application means for applying a discharge voltage to the corona discharger; A slit plate arranged so that a slit faces the charge wire of the corona discharger; and a slit plate provided opposite to the corona discharge device with the slit plate interposed therebetween, and charged by a leakage current obtained through a minute slit of the slit plate. A drum rotating means for rotating the drum; a sensor provided to face the drum, for detecting a drum surface potential charged by the leakage current; and a charge wire of the corona discharger. Moving means for synchronously moving the slit plate and the sensor, and a voltage change rate from an output of the sensor. A discharge unevenness measuring device for a corona discharger, comprising: determining means for detecting and determining discharge unevenness.