JP4865949B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as an electrophotographic printer such as a laser printer, an electrophotographic copying machine, and a fax machine.
[0002]
[Prior art]
As disclosed in Japanese Patent Application Laid-Open No. 9-211997, in an image forming apparatus using an electrophotographic technique, toner transfer from a toner carrier to a recording medium is performed on the back surface of the recording medium with a charge having a polarity opposite to that of the toner. To give a transcription. The charge on the recording medium does not easily disappear, and when the process proceeds as it is, the recording medium is electrostatically attracted to the toner carrier by this charge and is not peeled off. For this reason, in many image forming apparatuses, a peeling mechanism is provided for removing charges on the back surface of the recording medium after transfer. As an example, there is an AC static elimination mechanism that performs static elimination by irradiating the back surface of a recording medium with electric charges generated by the discharge of a corona wire to which an AC voltage is applied. It has a means for detecting the surface charge and impedance of the toner carrier, and variably controls the output of the peeling means according to the output value of the detection means, or has an output value detection means for the transfer means, depending on the output value. There are known devices that appropriately control the output of.
[0003]
[Problems to be solved by the invention]
However, even if the surface charge or impedance of the toner carrier is detected as in the prior art and the output of the peeling means is controlled according to the output of the detection means, the output characteristics of the peeling means are not constant, Proper peeling cannot be performed. Due to the reduction of the static elimination capability of the peeling means due to deterioration of the peeling means caused by paper dust or fixing oil adhesion, a low-rigidity recording medium, etc. may not be able to be peeled well and jams and defective images may occur. is there. If the antistatic performance of the peeling means is predicted to be lowered due to the deterioration of the peeling means in advance and the static elimination effect is set to be high, when the peeling means is not deteriorated, the amount of static elimination is too large to be recorded on the recording medium. In many cases, the transferred toner is reversely charged and reversely transferred to the toner carrier, and a good image cannot be obtained.
[0004]
[Means for Solving the Problems]
The present invention has been devised to solve the above-described problems, and includes a toner image carrier that holds a toner image, and a transfer unit that electrostatically transfers the toner image on the toner image carrier to a recording medium. An image forming apparatus having a peeling means for removing the charge applied to the back surface of the recording medium by the transfer means and peeling the recording medium from the toner image carrier, and having a storage means for storing a history of using the peeling means, The output of the peeling means is automatically corrected by predicting the attenuation of the output characteristics of the peeling means according to the usage history of the peeling means. Thereby, even if the static elimination effect is reduced due to deterioration of the peeling means, stable peeling can be performed.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing the configuration of the entire color electrophotographic apparatus.
[0006]
First, the color image forming process will be described with reference to FIG. In response to a print request from a controller (not shown), a synchronization signal that prompts image transmission is generated, and the controller transmits image data while the synchronization signal is active.
[0007]
The photosensitive member 1 is uniformly charged by the charger 7 while being rotated at a constant speed in the direction of the arrow by the driving means 3, and is exposed by the laser beam emitted from the exposure device 9 according to each color image signal. Corresponding electrostatic latent images are sequentially formed.
[0008]
The developing device 11, the developing device 12, the developing device 13, and the developing device 14 transmit a developing motor (not shown) that drives the developing roller 15, the developing roller 16, the developing roller 17, and the developing roller 18 and the driving force of the developing motor to the developing roller. A rotation control means (not shown) for controlling whether or not to perform, and a developing device contacting / separating means (not shown) for controlling whether or not the developing device 11, the developing device 12, the developing device 13, the developing device 14 and the photosensitive member 1 are brought into contact with each other. The electrostatic latent image is developed by applying a development voltage between the photosensitive member 1 and the developing roller 15, the developing roller 16, the developing roller 17, and the developing roller 18 to form a toner image on the photosensitive member 1.
[0009]
The toner image on the photoreceptor 1 is transferred onto the surface of the intermediate transfer body 2 that is driven while being in contact with the photoreceptor 1 by applying a first transfer voltage between the photoreceptor 1 and the intermediate transfer body 2. Thus, a color toner image is formed on the surface of the intermediate transfer member 2.
[0010]
The paper accumulated in the paper cassette 23 is picked up and conveyed from the paper cassette 23 by the paper feed roller 24, reaches the registration roller 25, temporarily stops, adjusts the posture of the paper, and the color toner image on the intermediate transfer body 2. Then, the color toner image on the intermediate transfer body 2 is transferred to a sheet by applying a mechanical pressing force of the transfer roller 26 and a second transfer voltage. In the process of forming a color toner image on the intermediate transfer body 2, the transfer roller 26 is not brought into contact with the intermediate transfer body 2 by a transfer roller contacting / separating means (not shown) and the second transfer voltage is not disturbed. Neither is applied.
[0011]
The sheet on which the color toner image has been transferred is peeled off from the intermediate transfer body 2 by the AC static eliminator 28, sent to the fixing unit 29, and the color toner image is thermally fixed on the sheet surface while passing through the fixing unit 29, The sheet on which the toner image has been thermally fixed is discharged out of the apparatus by a discharge roller 30.
[0012]
Next, the control of the AC static eliminator will be described with reference to FIGS. FIG. 2 shows an example of the configuration of the invention for automatically correcting and controlling the output of the AC static eliminator according to the use history of the AC static eliminator. This peeling system includes an AC static eliminator 28, an AC static eliminator power supply means 40, a system control means 31, a storage means 50, a transfer roller 26, a transfer power supply and current detection means 41, and the intermediate transfer body 2.
[0013]
The system control unit 31 controls the AC static eliminator 28 so as to neutralize the charge of the sheet charged by the transfer. The system control unit 31 controls the potential on the back side of the paper according to the amplitude of the AC voltage value, the DC superimposed voltage value, and the ratio of the on / off time of the AC voltage, which are the outputs of the AC neutralizer power source unit 40. The sheet is charged positively by the transfer voltage. If the system control means 31 controls the amplitude of the AC voltage value, which is the output of the AC static eliminator power supply means 40, to increase, the back side of the paper is more negatively charged. Further, if the system control means 31 shifts the DC superimposed voltage value, which is the output of the AC static eliminator power supply means 40, to the negative side, the back side of the paper is more negatively charged. Further, if the system control unit 31 performs control so that the ON time of the AC voltage ON / OFF time that is the output of the AC neutralizer power supply unit 40 is increased, the back surface of the sheet is more negatively charged. As a result, the positively charged paper is negatively charged, the potential is neutralized, and the potential difference between the surface of the intermediate transfer body 2 and the back surface of the paper is reduced to facilitate peeling.
[0014]
The transfer voltage value is determined by information on the environment (temperature and humidity, etc.) and the state of the paper obtained by measuring the electrical characteristics of the entire transfer means and the paper. At the time of transfer, a transfer voltage of about 3.5 KV to about 800 V is applied to the transfer roller. Similarly, the amplitude of the AC voltage value, the superimposed DC voltage value, and the on / off time ratio of the AC voltage, which is the output of the AC static elimination, are obtained by measuring the electrical characteristics of the entire transfer means and the electrical characteristics of the paper. (Temperature and humidity, etc.) and paper state (humidity) information are determined.
[0015]
The electrical characteristics of the entire transfer means are such that when there is no toner image on the intermediate transfer body 2 such as warming up of the printer device, the transfer roller 26 is brought into contact with the intermediate transfer body 2 by a transfer roller contact / separation mechanism (not shown). Measurement can be performed by applying a certain voltage by the detecting means 41 and the current flowing through the transfer roller 26. In addition, when the toner image on the intermediate transfer member 2 is transferred to the paper, the paper is brought into contact with the transfer roller 26 at a position other than the printing area at the front end of the paper, and the transfer power supply and current detection means 41 are used to generate a certain voltage. Is measured by the current flowing through the transfer roller 26 that is in contact with the intermediate transfer body 2 via the sheet. Also, the paper type (plain paper, cardboard, label paper, OHP, etc.) may be given by an information input means (not shown).
[0016]
The system control unit 31 outputs the AC static eliminator 28 suitable for the environment in which the printer is installed, the state of the paper, and the type of paper, that is, the amplitude of the AC voltage value, the DC superimposed voltage value, and the on / off state of the AC voltage. Temporarily determine the percentage of time. The system control unit 31 stores, in the storage unit 50, usage history information indicating how many sheets have been printed using the AC static eliminator 28 every time printing is performed. The storage means 50 is constituted by a rewritable nonvolatile memory or the like. FIG. 3 is an example showing a value for correcting the amplitude of the AC voltage value based on the use history of the AC static eliminator. The value to be corrected may be a DC superimposed voltage value or an AC voltage on / off time ratio. The content of FIG. 3 considers a reduction in static elimination capability due to deterioration of the AC static eliminator 28 such as adhesion of paper dust or fixing oil, and the amplitude of the AC voltage value increases as the usage history of the AC static eliminator, that is, the number of used static electricity increases. The correction value is increased. The data table having the configuration shown in FIG. 3 is stored in a memory means such as a ROM (not shown) that constitutes the system control means 31.
[0017]
The system control unit 31 temporarily determines the output control value of the AC static eliminator 28 suitable for the environment in which the printer is installed, the state of the paper, and the type of paper, and then uses the AC static eliminator 28. Information is read from the storage means 50. The correction value is referred to from the data table having the configuration shown in FIG. 3 in accordance with the AC static eliminator usage history information, and the correction value is added to the temporarily determined control value for the AC static eliminator power supply means 40. In this way, even if the neutralization effect is reduced due to the deterioration of the AC static eliminator, the control value to the AC static eliminator power supply means 40 is corrected based on the usage history of the AC static eliminator 28 so that the neutralization effect is further increased. Thus, stable peeling can be performed. When the AC static eliminator has reached the end of its life and is replaced, the usage history information of the AC static eliminator 28 stored in the storage means 50 is cleared, and the control value for the AC static eliminator power supply means 40 immediately after the start of use is corrected. So that is appropriate.
[0018]
By the way, a plurality of data tables shown in FIG. 3 may be provided, and an operation may be performed by selecting an appropriate one from the plurality of data tables by a selection unit (not shown). The plurality of data tables are stored in advance in a memory means such as a ROM (not shown) constituting the system control means 31 in advance. A table that is considered to be most appropriate corresponding to the attenuation characteristic of the output due to the deterioration of the AC static eliminator is selected by a selection means (not shown), and the control value to the AC static eliminator power supply means 40 is corrected. The system control unit 31 temporarily determines a control value for the AC discharger power supply unit 40 suitable for the environment in which the printer is installed, the state of the sheet, and the type of the sheet, and then the AC discharger 28. Usage history information is read from the storage means 50. A data table is selected from a plurality of data tables stored in a memory means such as a ROM by a selection means (not shown), and a correction value is referred to according to AC static electricity use history information to temporarily determine AC removal. The correction value is added to the control value for the electric power supply means 40. In this way, it is possible to change the correction amount, and even when the attenuation characteristic of the output due to the deterioration of the AC static eliminator 28 is not predicted but is desired to be changed, it can be controlled with an appropriate correction value. Thus, more stable peeling can be performed.
[0019]
By the way, the data table having the configuration shown in FIG. 3 is input to the system control unit 31 by an input unit (not shown), and the control value to the AC neutralizer power source unit 40 is corrected according to the data table input from the outside. May be. A data table input from the outside by an input unit (not shown) is stored in the storage unit 50 by the system control unit 31. The system control unit 31 temporarily determines a control value for the AC discharger power supply unit 40 suitable for the environment in which the printer is installed, the state of the sheet, and the type of the sheet, and then the AC discharger 28. Usage history information is read from the storage means 50. In accordance with the AC static eliminator usage history information, the correction value is referred to from the externally input data table stored in the storage means 50, and the correction value is set to the temporarily determined control value for the AC static eliminator power supply means 40. to add. In this way, it is possible to arbitrarily determine the amount of correction from the outside, and even when the attenuation characteristics of the output due to deterioration of the AC static eliminator are not expected and are to be changed, the correct correction value can be used. It becomes possible to control and more stable peeling can be performed.
[0020]
【Effect of the invention】
As described above, according to the present invention, the control value of the peeling means is automatically corrected based on the use history of the peeling means even in a state where the static elimination ability of the peeling means is reduced due to deterioration of the peeling means, and stable peeling is achieved. Can be done.
[Brief description of the drawings]
FIG. 1 is a block diagram showing the overall configuration of a color electrophotographic apparatus.
FIG. 2 is an AC static eliminator control block diagram.
FIG. 3 is a data table that defines the relationship between the use history of the AC static eliminator and the correction amount of the output of the AC static eliminator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Photoconductor, 2 ... Intermediate transfer body, 3 ... Drive means, 7 ... Charger, 9 ... Exposure apparatus, 11, 12, 13, 14 ... Developing apparatus, 15, 16, 17, 18 ... Developing roller, 19 ... Developing motor, 23 ... paper cassette, 24 ... feed roller, 25 ... registration roller, 26 ... transfer roller, 28 ... AC static eliminator, 29 ... fixing device, 30 ... discharge roller, 31 ... system control means, 40 ... AC Static eliminator power supply means 41... Transfer power supply and current detection means 50.

Claims (3)

A toner image carrier that holds the toner image transferred from the photosensitive member; a transfer unit that electrostatically transfers the toner image on the toner image carrier to a recording medium; In the image forming apparatus having a peeling means for removing the charged charges and peeling the recording medium from the toner image carrier,
The image forming apparatus includes: a transfer power source for the transfer unit ; and a current detection unit that detects the current of the transfer unit in contact with the toner image carrier or in contact with the toner image carrier through paper. If the storage means for storing the history of use peeling means, before SL output of the correction amount and the peeling means follow the correction value of the data table defining the relationship between the use history and the peeling means of the peeling means Control means for automatically correcting the attenuation of the output characteristic of the peeling means according to the use history ,
The control means temporarily determines an output control value of the peeling means based on a detection value of the current detection means when a certain voltage is applied by the transfer power supply , and uses the peeling means from the storage means. An image forming apparatus comprising: reading a history, referring to the data table according to the usage history, and adding the correction value to the output control value.   The selection state storage means according to claim 1, wherein the data table defines a relationship between a use history of the peeling means and a correction amount of the output of the peeling means, and selects the data table and stores a selection state. And an image forming apparatus that automatically corrects the output of the peeling means according to a selected state.   2. The input means for inputting the data table defining the relationship between the use history of the peeling means and the correction amount of the peeling means from outside the apparatus according to claim 1, and the storage for storing the inputted data table And an image forming apparatus for automatically correcting the output of the peeling means according to the inputted data table.

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