JP2004252305A - Image formation unit, method for adjusting image formation unit and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing unit and an image forming apparatus in which electrification is excellently adjusted even when individually replacing the developing unit or a single photoreceptor. <P>SOLUTION: By arranging a unit sensitivity adaptable adjusting means for adjusting voltage to a main charger given to a feed part in accordance with discharge characteristic caused by the attaching position of the main charger provided in the developing unit, and a photoreceptor sensitivity adaptable adjusting means for adjusting the voltage to the main charger given to the feed part in accordance with the sensitivity of the photoreceptor, the developing unit is replaced without performing difficult adjustment. Furthermore, when replacing only the single photoreceptor, the developing unit where the photoreceptor is replaced is adjusted by an easy method. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming unit and an image forming apparatus provided with a photoreceptor, and more particularly, to an image forming unit and an image forming apparatus that keep a potential charged on a photoreceptor constant.
[0002]
[Prior art]
The development conditions in the image forming apparatus include various conditions such as a potential charged on a photoconductor, which is an example of an image carrier, an amount of a developer on the photoconductor, an ambient environment, and a use condition. The image quality fluctuates depending on these conditions, and among them, the image quality is greatly affected by the potential charged on the photoconductor. If the charging potential fluctuates, the amount of the developer that forms an image on the photoconductor also fluctuates, and the density of the formed image also fluctuates. That is, the potential charged on the photoreceptor is an important parameter that determines the shading of the formed image, and it is necessary to keep the potential charged on the photoreceptor always within a specified range in order to maintain a constant image quality.
[0003]
However, since the photoconductors generally have different sensitivity characteristics, even when a constant voltage is applied to each of the plurality of photoconductors, for example, the potential charged on the photoconductors differs for each photoconductor. .
Therefore, if it is determined that the photoconductor is abnormal, simply replacing the photoconductor causes a difference in the sensitivity characteristics of the photoconductor, resulting in a different potential charged on the photoconductor, which has a great adverse effect on image quality. In this case, it is necessary to adjust the potential charged on the photoconductor after replacement within a specified range.
Further, a main charger for charging the photosensitive member is provided in the image forming unit, and the position at which the main charger is attached to the image forming unit is slightly different for each unit. As a result, the discharge space formed between the main charger and the photoconductor fluctuates, and such fluctuation in the discharge space also affects the discharge characteristics (attenuation of discharge voltage) of the main charger.
Patent Document 1 proposes an image forming apparatus capable of easily adjusting a charging potential of a photoconductor to a specified value. A variable resistor having a plurality of terminals is provided in a power supply circuit for the main charger provided on the image forming apparatus main body side, and an input voltage to the main charger is changed for each image forming unit by changing a resistance value of the variable resistor. Is to adjust.
[0004]
[Problems to be solved by the invention]
However, the adjustment of the charging potential of the photosensitive member described in Patent Document 1 is performed by adjusting the sum of the sensitivity characteristics of the photosensitive member and the main charger of the image forming unit as the sensitivity of the image forming unit. is there. In this case, the sensitivity of the entire image forming unit must be adjusted again when the single photosensitive member is replaced, regardless of whether the image forming unit is replaced. This is because, as described above, the charging potential varies depending not only on the sensitivity characteristics of the photoconductor, but also on the discharge characteristics due to the mounting position of the main charger of the image forming unit. Such readjustment is not easy and has required a great deal of effort.
Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image forming unit capable of favorably adjusting a charged potential even when an image forming unit or a single photosensitive member is separately replaced. And an image forming apparatus.
[0005]
[Patent Document 1]
JP-A-7-261517
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a discharge unit which is detachable from an image forming apparatus and has at least an image forming unit having a photoreceptor, which is caused by a mounting position of a main charger provided in the image forming unit. Unit sensitivity adjusting means for adjusting the voltage to the main charger applied to the power supply unit in accordance with the sensitivity, and the photoconductor sensitivity for adjusting the voltage to the main charger applied to the power supply unit in accordance with the sensitivity of the photoconductor And a corresponding adjusting means.
With this configuration, the image forming unit can be replaced without any special adjustment, and when only the photosensitive member alone is replaced, the image forming unit with the replaced photosensitive member can be replaced by a simple method. It is possible to adjust the charging potential of the photoreceptor by performing the adjustment. Further, since each of the adjusting means is provided not in the image forming apparatus but in the image forming unit, the adjustment is further facilitated. In this case, it is desirable that the photoconductor sensitivity adjustment unit selects and adjusts the photoconductor sensitivity range divided into a plurality of ranges in advance.
[0007]
Further, the unit sensitivity adjustment unit and / or the photoconductor sensitivity adjustment unit may be mounted on a circuit board mounted on the image forming unit. As a result, the size of the image forming unit can be reduced. Further, it is preferable that the unit sensitivity adjusting means and / or the photoconductor sensitivity adjusting means adjust by selecting an element, a switch or a volume mounted on the circuit board.
[0008]
Further, the present invention may be regarded as an adjustment method for performing a process corresponding to each unit of the image forming unit. That is, in the method of adjusting an image forming unit that is detachable from the image forming apparatus and has at least a photoconductor, the power supply is performed in accordance with a discharge characteristic caused by a mounting position of a main charger provided in the image forming unit. A unit sensitivity adjustment step of adjusting a voltage applied to the main charger to the unit, and a photoconductor sensitivity adjustment step of adjusting a voltage applied to the main charger to the power supply unit according to the sensitivity of the photoconductor. The image forming unit can be configured as a method for adjusting the image forming unit.
[0009]
Further, the present invention may be embodied as an image forming apparatus in which the image forming unit is detachably mounted.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings to facilitate understanding of the present invention. The following embodiments are examples embodying the present invention, and do not limit the technical scope of the present invention.
FIG. 1 is a sectional view of an image forming apparatus provided with an image forming unit X according to the embodiment of the present invention, FIG. 2 is a partial perspective view of the image forming unit X according to the embodiment of the present invention, and FIG. FIG. 4 is a partial perspective view showing a substrate storage state in the image forming unit X according to the embodiment of the present invention, and FIG. 4 is a state in which the side cover and the circuit board of the image forming unit X according to the embodiment of the present invention are assembled. FIG. 5 is a diagram showing an adjustment circuit board of the image forming unit according to the embodiment of the present invention, and FIG. 6 is an adjustment circuit diagram of the sensitivity adjustment circuit board according to the embodiment of the present invention.
[0011]
First, a digital copying machine 10 as an example of an image forming apparatus including an image forming unit X according to an embodiment of the present invention will be described with reference to FIG. The image forming unit X can be applied to an image forming apparatus such as a copying machine, a facsimile apparatus, and a printer.
The digital copying machine 10 has a plurality of recording paper storage units 11 below, and a double-sided unit 12 is disposed on a side surface thereof. An image forming unit 13 and a fixing device 3 are provided above the recording paper storage unit 11. Further, an image reading device 14 is provided on the upper part. A display operation unit such as a liquid crystal touch panel (not shown) is disposed on the upper surface of the main body of the digital copying machine 10. The user operates the display operation unit to select an image quality mode or to control the plurality of recording paper storage units 11. The user performs various operations such as selection of which of the recording paper cassettes to use and start of image reading.
[0012]
The image forming unit 13 is provided with an image forming unit X that is detachable from the digital copying machine 10 and includes a photosensitive drum 16 and a main charger 17, a cleaning device 19, and the like arranged around the photosensitive drum 16. A developing device 18 and a transfer device 20 facing the photosensitive drum 16 are disposed near the developing device 18. In the main charger 17 and the like, the image forming unit X is mounted on the digital copying machine 10, and a power terminal (not shown) provided on the digital copying machine 10 and a power terminal (not shown) provided on the image forming unit X side are connected. Power is supplied by being connected. The photosensitive drum 16 has a photosensitive layer formed on the surface of, for example, an aluminum cylinder, and is driven to rotate clockwise in FIG. The main charger 17 charges the surface of the rotating photosensitive drum 16 to several hundred volts by corona discharge or the like. A laser beam emitted from the writing unit 5 is irradiated on the surface of the photosensitive drum 16 on the downstream side in the rotation direction from the main charger 17 to form an electrostatic latent image.
[0013]
In the developing device 18, the developing roller rotates, and the thin layer formed on the surface of the developing roller comes into contact with the surface of the photosensitive drum 16, and the charged toner adheres to the electrostatic latent image on the surface of the photosensitive drum to form a toner image. Form. The toner image is charged while being transported in the transfer device 20 in a state where the recording paper transported from the recording paper storage unit 11 is sandwiched between the photosensitive drum 16 and the transfer belt moving at the same speed as the peripheral speed. Then, the toner image is transferred onto the recording paper. A cleaning device 43 is disposed downstream of the transfer device 20, and removes toner and other deposits remaining on the surface of the photosensitive drum 16.
[0014]
The recording paper onto which the toner image has been transferred by the transfer device 20 is conveyed to a fixing device 3 provided on the downstream side in the conveying direction, and the space between the fixing roller 1 of the fixing device 3 and the pressure roller 2 opposed thereto is fixed. As described above, the toner on the recording paper is fused and fixed by the heat of the fixing roller 1 having a heater therein. The pressure roller 2 presses the recording paper against the fixing roller 1 to ensure that the toner is fixed.
[0015]
Next, the schematic configuration of the image forming unit X will be described with reference to the partial perspective views of FIGS. 2 and 3 and the perspective view of FIG.
As shown in FIG. 2, in addition to the photoconductor 16 and the main charger 17, a side cover 22 for mounting and dismounting the photoconductor 16 and a circuit board near the side cover 22 are provided in the image forming unit X. It is constituted by a circuit board storage part 23 for storing.
As shown in FIG. 3 showing a state in which the side cover 22 is opened, a sensitivity adjustment circuit board 31 is attached to the circuit board storage section 23. Further, the sensitivity adjustment circuit board 31 adjusts a voltage applied to the power supply unit to the main charger 17 in accordance with a discharge characteristic caused by a mounting position of the main charger 17 provided in the imaging unit X. An adjusting means (described later) and a photoconductor sensitivity corresponding adjusting means (described later) for adjusting the voltage to the main charger 17 applied to the power supply unit according to the sensitivity of the photoconductor 16 are provided.
[0016]
Further, the sensitivity adjustment circuit board 31 will be described with reference to FIGS.
The sensitivity adjustment circuit board 31 includes at least a variable resistor 33 as an example of the unit sensitivity adjustment means, a changeover switch 32 as an example of the photoconductor sensitivity adjustment means, and three types of fixed resistors having different resistance values. Elements (r1, r2, r3) (FIG. 5) are mounted. The changeover switch 32 includes a short-circuit pin 32a and a short-circuit socket 32b for connecting an electric circuit by being inserted into the short-circuit pin 32a, thereby switching the fixed resistance element. The changeover switch 32 may be a dip switch, a dial switch, a push button switch, or the like.
[0017]
Next, a description will be given of a means for adjusting the voltage applied to the main charger 17 to the power supply unit by the variable resistor 33 in accordance with the discharge characteristics caused by the mounting position of the main charger 17. Such adjustment is performed in order to eliminate the variation in the charged potential of the photoconductor caused by the difference in the discharge characteristics for each image forming unit.
Here, the discharge characteristics refer to the amount of attenuation of the discharge voltage of the main charger 17 due to a discharge space formed between the main charger 17 attached to the image forming unit and the photoconductor 16. When the discharge space fluctuates due to a variation in the mounting position of the main charger 17, the amount of attenuation of the discharge voltage also fluctuates. Accordingly, the discharge voltage to the photoconductor 16 also fluctuates, and as a result, the potential charged on the photoconductor 16 varies.
The power supply unit refers to a high-voltage power supply for supplying high-voltage power to the main charger 17, the high-voltage power supply circuit, and other devices related thereto. FIG. 6 shows an adjustment circuit of the sensitivity adjustment circuit board 31 adjusted by the variable resistor 33 and the changeover switch 32.
First, it is necessary to accurately measure only the discharge characteristics. For this purpose, the sensitivity of the imaging unit X is adjusted by attaching a photoconductor having a specified sensitivity (reference sensitivity) to the imaging unit X or a test tool having the reference sensitivity and replacing the photoconductor. In addition, it is necessary to switch the changeover switch 32 to a reference resistance element (for example, r2) for measuring the discharge characteristics (see FIG. 6). Measuring the sensitivity of the entire imaging unit X under such conditions is nothing more than measuring the discharge characteristics. After measuring the discharge characteristics, the combined resistance of the power supply unit is changed by changing the variable resistor 33. As a result, the voltage applied to the power supply unit is changed, that is, the voltage applied to the power supply unit to the main charger 17 can be adjusted.
As described above, the variable resistor 33 that adjusts the voltage to the main charger 17 applied to the power supply unit in accordance with the previously measured discharge characteristic caused by the mounting position of the main charger 17 corresponds to the unit sensitivity adjustment means. [0018]
Next, means for adjusting the voltage to the main charger 17 to be supplied to the power supply unit according to the sensitivity of the photoconductor 16 by the switch 32 will be described. Such adjustment is performed in order to eliminate the variation in the charged potential of the photoconductor due to the difference in the sensitivity characteristic of the photoconductor for each photoconductor.
First, it is necessary to measure in advance the sensitivities of all the photoconductors 16 alone using a resistance measuring device or the like. Usually, the measured sensitivity differs for each photoconductor, but most of them are included in a certain sensitivity range. The photoconductors included in this sensitivity range are divided into three groups (R1, R2, R3) in order of the magnitude of the sensitivity characteristic.
When the fixed resistance elements r1 to r3 are connected in series with the photoconductor 16, the fixed resistance elements r1 to r3 are combined with an average value of sensitivity characteristics of the photoconductors belonging to the group R1 and r1 and the combined sensitivity of the photoconductors belonging to the group R2. The resistance element is such that the combined sensitivity of the average value of the sensitivity characteristics and r2 and the combined sensitivity of the average value of the sensitivity characteristics of the photoreceptors belonging to the group R3 and r3 have the same value (specified value). That is, when the photosensitive member belonging to the group R1 is mounted on the unit, the electric circuit is switched to the fixed resistance element r1 side by the changeover switch 32, and when the photosensitive member belonging to the group R2 is mounted on the unit, the electric circuit is switched to the fixed resistance element. When the photosensitive member belonging to the group R3 is mounted on the unit, the electric path is switched to the fixed resistor element r3 side, thereby switching the sensitivity of the photosensitive member 16 and the combined sensitivity of the switched fixed resistor element. The characteristics are always kept substantially constant (specified value) (see FIG. 6). Thus, the voltage applied to the main charger 17 to the power supply unit can be adjusted to be constant.
The sensitivity range (R1, R2, R3) needs to be determined so that the combined sensitivity of the corresponding fixed resistance element and the photoconductor falls within a specified range (within an allowable range).
As described above, the changeover switch 32 that adjusts the voltage to the main charger 17 applied to the power supply unit according to the sensitivity range of the photoconductor 16 measured in advance corresponds to the photoconductor sensitivity adjustment unit.
[0019]
【The invention's effect】
As described above, according to the present invention, the unit sensitivity for adjusting the voltage applied to the power supply unit to the main charger in accordance with the discharge characteristics caused by the mounting position of the main charger provided in the image forming unit. An image forming apparatus without special adjustment is provided by including a corresponding adjusting means and a photosensitive member sensitivity adjusting means for adjusting a voltage to the main charger applied to the power supply section according to the sensitivity of the photosensitive member. The unit can be replaced, and when only the photosensitive member alone is replaced, the image forming unit with the replaced photosensitive member can be adjusted by a simple method. In addition, since each of the adjusting means is provided not in the image forming apparatus but in the image forming unit, the replacement work of the user is further facilitated.
In addition, by dividing the sensitivity of the photoconductor into a plurality of ranges in advance, the adjustment method when replacing the photoconductor alone can be simplified.
[Brief description of the drawings]
FIG. 1 is a sectional view of an image forming apparatus including an image forming unit X according to an embodiment of the present invention.
FIG. 2 is a partial perspective view of the image forming unit X according to the embodiment of the present invention.
FIG. 3 is a partial perspective view showing a substrate storage state in the image forming unit X according to the embodiment of the present invention.
FIG. 4 is a perspective view showing a state where a side cover and a circuit board of the image forming unit X according to the embodiment of the present invention are assembled.
FIG. 5 is a diagram showing an adjustment circuit board of the image forming unit according to the embodiment of the present invention.
FIG. 6 is an adjustment circuit diagram of the sensitivity adjustment circuit board according to the embodiment of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 fixing roller 2 pressure roller 3 fixing device 4 display operation unit 5 writing unit 10 digital copying machine 11 recording paper storage unit 12 duplex unit 13 image forming unit 14 image reading device 16 photosensitive Drum 17 Main charger 18 Developing device 19 Cleaning device 20 Transfer device 22 Side cover 23 Circuit board housing 31 Sensitivity adjustment circuit board 32 Changeover switch 32a Changeover pin 32b Changeover socket 33 Variable resistor r1, r2, r3 ... fixed resistance elements

Claims (6)

In an image forming unit detachable from the image forming apparatus and having at least a photoconductor,
Unit sensitivity correspondence adjusting means for adjusting a voltage applied to the power supply unit to the main charger in accordance with a discharge characteristic caused by a mounting position of the main charger provided in the image forming unit;
Adjusting means for adjusting the voltage applied to the power supply unit to the main charger in accordance with the sensitivity of the photoconductor;
An image forming unit comprising: 2. The image forming unit according to claim 1, wherein said photoconductor sensitivity adjustment means selects and adjusts a photoconductor sensitivity range previously divided into a plurality of ranges. The image forming unit according to claim 1, wherein the unit sensitivity adjusting means and / or the photoconductor sensitivity adjusting means are mounted on a circuit board mounted on the image forming unit. 4. The device according to claim 1, wherein the unit sensitivity adjustment unit and / or the photoconductor sensitivity adjustment unit adjusts by selecting an element, a switch, or a volume mounted on the circuit board. Imaging unit. In a method of adjusting an image forming unit that is detachable from an image forming apparatus and has at least a photoconductor,
A unit sensitivity corresponding adjusting step of adjusting a voltage applied to the power supply unit to the main charger according to a discharge characteristic caused by a mounting position of the main charger provided in the image forming unit;
Adjusting a voltage applied to the power supply unit to the main charger in accordance with the sensitivity of the photosensitive member. An image forming apparatus, wherein the image forming unit according to claim 1 is detachably attached.

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