JP2000105523A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To advance to the following image forming process without leaving a charge of reverse polarity on a photoreceptor in the event of emergency stop and keep satisfactory image quality by stopping a photoreceptor drive motor after it is rotated until the surface of the photoreceptor is statically eliminated by a releasing static eliminator, when a jam occurs, thereafter stopping a development bias, and turning off the releasing static eliminator. SOLUTION: A photoreceptor rotation control means in jam occurrence C1a rotates a photoreceptor drive motor M1 until the surface of a photoreceptor PR to which a transfer voltage is applied by a sheet transfer device Tp is statically eliminated by a releasing static eliminator DTC, and then stops it. A development bias control means in jam occurrence C3a stops a development bias after the photoreceptor PR is stopped in jam occurrence. A releasing static eliminator control means in jam occurrence turns off the releasing static eliminator DTC after the surface of the photoreceptor PR to which the transfer voltage is applied by the sheet transfer device Tp in jam occurrence is statically eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of forming an electrostatic latent image on the surface of a photoreceptor that rotates and developing the electrostatic latent image into a toner image, and transferring the developed toner image to a sheet. For image forming apparatuses such as electrophotographic copying machines and printers for forming, especially when an emergency stop occurs when a jam occurs, the charge history is not left on the photoreceptor surface charged before the emergency stop, and the image quality based on the charge history The present invention relates to an image forming apparatus configured to prevent a drop.

[0002] In the present specification, the "toner image carrier" has the following meaning. Toner Image Carrier: (1) The photoconductor in which an electrostatic latent image formed on the surface of a uniformly charged photoconductor is developed into a toner image, the photoconductor carrying a toner image on the surface. (2) An intermediate transfer member (an intermediate transfer belt or an intermediate transfer drum) on which a toner image is temporarily transferred from the surface of the photoreceptor, wherein the intermediate transfer member carries a toner image on the surface.

In the present specification, the “paper” has the following meaning. (3) a sheet on which a toner image is finally transferred, such as a recording sheet or an OHP sheet; (4) an intermediate transfer body (an intermediate transfer belt or an intermediate transfer drum) on which a developed toner image is transferred onto the surface of a photoreceptor;

[0004] As can be seen from the above description, the "intermediate transfer member" is a "paper" when the developed toner image is primarily transferred to the surface of the photoreceptor.
In the case where the next transfer toner image is secondarily transferred to the final sheet (sheet or the like), it is a “toner image carrier”.

[0005] In the present specification, "jam" means that the paper remains in the paper transport path or the tray and is normally transported between the time the image forming apparatus starts the image forming operation and the time the image forming operation ends. This means a state in which the apparatus detects an image forming operation that has not been performed, and it is necessary to urgently stop the image forming operation. Therefore, besides "jam" such as paper jam, there is a state in which it is necessary to urgently stop the image forming operation even when an abnormality occurs in the control of the image forming operation during the copying operation. Such a state is also referred to as “jam”.

[0006]

2. Description of the Related Art Conventionally, the following image forming apparatus is known as an image forming apparatus for developing an electrostatic latent image on the surface of a photoreceptor into a toner image and transferring the toner image to a sheet. (1) An image forming apparatus for directly transferring a toner image on a photoreceptor surface to final paper such as paper. (2) An image forming apparatus for temporarily transferring a toner image on a photosensitive member surface to an intermediate transfer member and indirectly transferring the toner image from the intermediate transfer member to a final sheet such as a sheet.

[0007] As an image forming apparatus for directly transferring the toner image on the surface of the photoreceptor to the final sheet, for example, an image forming apparatus having the following constitutional requirements is known. (1) a charged area in which the rotating surface faces the charger;
A photosensitive element that sequentially passes through a latent image writing position where light corresponding to an image is irradiated, a developing area facing a developing roll, a sheet transfer area (area to be transferred to paper), and a sheet peeling area (area to peel off paper). (2) a charger for charging the surface of the photosensitive member when the surface of the rotating photosensitive member passes through the charging area; and (3) a charger for charging the surface of the photosensitive member when passing the latent image writing position. A latent image forming apparatus for forming an electrostatic latent image, (4)
A developing device for developing the electrostatic latent image on the photoconductor surface into a toner image when passing through the development area; (5) developing the toner image when the toner image on the photoconductor surface passes through the paper transfer area; (6) a paper transfer device for transferring to a paper, (6) disposed in the paper peeling area adjacent to the downstream side of the paper transfer area along the moving direction of the photoreceptor surface, and discharging the paper passing through the paper transfer area; (7) a pair of fixing rotating members that form a fixing area by areas that are in pressure contact with each other, and heat-fix a toner image on a sheet passing through the fixing area. Fixing device,
(8) a discharge tray for storing paper on which the toner image is fixed, and (9) a plurality of paper trays for storing paper such as OHP paper and normal paper, wherein each paper is transferred to the paper transfer area. A paper conveyance device that sequentially conveys to the fixing area and the paper discharge tray.

[0008]

During the image forming operation in the image forming apparatus, various motors such as a photoreceptor drive motor and a paper transport roll drive motor, and various power supplies such as a power supply for a charger, a power supply for a transfer device, a power supply for a developing bias and the like. Is turned on. If a jam (paper jam) occurs in this state, the various motors and the power supply circuit are emergency stopped. When the jam occurs, there is a case where the transfer voltage is turned on even though the paper to be conveyed to the transfer area is not conveyed to the transfer area. The image forming apparatus that has been emergency stopped due to the jam uses a photoconductor charged to-(minus), a toner having a charging polarity of-(minus), and uses a + (plus) charger as a transfer unit. In the case, during the emergency stop, the surface of the photoreceptor is transferred to the normal
There is a case where the motor stops in a state where it is charged to + (plus) having a polarity opposite to that of (minus) charge.

The positive (+) charge on the photoreceptor surface is:
Since it does not disappear even through the light erasing means, a desired charging potential is not attained when the next charging step is started, so that there is a problem that image quality defects such as fog and black stripes are easily generated. This problem is caused by the fact that the image forming apparatus that has been emergency stopped due to the jam has a photoconductor charged to + (plus) and the charging polarity is +
Use (plus) toner and transfer device-(minus)
The same applies to the case where the charging device of (1) is used.

Conventionally, techniques relating to stop timing at the time of emergency stop of an image forming apparatus are disclosed in JP-A-4-67153, JP-A-4-67159, and JP-A-4-6716.
Although described in Japanese Patent Laid-Open Publication No. 0-205, no consideration is given to the problem when the photoconductor is charged to the opposite polarity by the transfer device. Generally, an operation (recovery job) for returning to a normal state when restarting after an emergency stop is performed, but the recovery job does not remove the charged charge on the surface of the photoreceptor. This is a job for cleaning toner stains.

In the prior art described in Japanese Patent Application Laid-Open No. 6-318027, the drive of the photoconductor and the fall time of the power of the transfer unit and the driving device of the photoconductor are also performed because the drive of the photoconductor and the transfer unit are stopped at the same time during an emergency stop. There is a problem that the reversely charged electric charge by the transfer means remains on the photoreceptor due to the inertia force.
For this reason, in the next charging step, the area charged to the opposite polarity (plus) by the transfer unit does not reach the original charge amount, so that the latent image and the developed image are affected, and image quality such as fog is reduced. Sometimes. For example, if the area charged to the opposite polarity is charged to +200 V after the emergency stop, the next time the charging area is charged by the charger, the charged area of the opposite polarity can only be charged to -650 V against the desired value of -700 V. That situation occurs. When this portion is subjected to reversal development (developing by irradiating light not on the background portion but on the image portion and developing the light irradiating portion into a toner image), toner easily adheres and causes fogging.

The present invention has been made in view of the above research and examination results, and has an object of the following content (O01). (O01) To enable the image forming apparatus to enter the next image forming process without leaving a charge having a polarity opposite to the original charge polarity on the photosensitive member during an emergency stop of the image forming apparatus, and to maintain good image quality. .

[0013]

Next, the present invention devised to solve the above-mentioned problems will be described. Elements of the present invention are used to facilitate correspondence with elements of the embodiments described later. , The reference numerals of the elements of the embodiment are enclosed in parentheses. The reason why the present invention is described in correspondence with the reference numerals of the embodiments described below is to facilitate understanding of the present invention, and not to limit the scope of the present invention to the embodiments.

(1st invention) In order to solve the aforementioned problem,
The image forming apparatus of the first invention of the present application has the following requirements (A0
(A01) A charged area (Q0) whose rotating surface faces a charger (CSC), and a latent image writing to which light corresponding to an image is radiated. A photoconductor (PR) sequentially passing through a position (Q1), a development area (Q2) facing the development roll, a paper transfer area (QP), and a paper peeling area (Q4), wherein the rotating surface is the photoconductor (PR); It is charged when passing through the charging area (Q0), an electrostatic latent image is formed when the charged surface passes through the latent image writing position (Q1), and the electrostatic latent image is transferred to the developing area (Q2). )
Is developed into a toner image when passing through the sheet, the toner image is transferred to the sheet (S) in the sheet transfer area (QP), and the sheet (S) is transferred to the photoconductor (PR) in the sheet peeling area (Q4). The photoconductor (P) peeled off from the surface
R), (A02) A photoreceptor rotation drive device having a photoreceptor drive motor (M1) for driving the photoreceptor (PR) to rotate and a photoreceptor drive circuit (DM1) for driving the photoreceptor drive motor (M1) (M1 + DM1), (A03) The charged area (Q
A charging device (CSC + E2) having a charger (CSC) for charging the surface of the photoreceptor (PR) rotating in 0) and a charger power supply (E2) for applying a charging voltage to the charger (CSC); (A04) a developing roll (DR) for conveying the toner adhered to the rotating surface to the developing area (Q2), a developing roll rotation driving device (DM2 + M2) for rotating the developing roll (DR), and The developing bias for developing the electrostatic latent image into a toner image with toner on the surface of the roll (DR) is changed to the developing roll (D).
R) and a developing device (D + DM2 + M2 + E) having a developing bias power supply (E1) applied between the photoreceptor (PR).
1), (A05) a paper transfer device (TP) arranged in the paper transfer area (QP), and a transfer voltage for transferring the toner image to the paper (S) are applied to the photoconductor (PR) and the paper transfer device ( Paper transfer device (E3 + TP) having a transfer power supply (E3) applied between TP) and (A06) paper feed trays (TR1 to
TR3) to transport the sheet (S) stored in the sheet transfer area (QP) to the sheet transfer area (QP), (A07) the sheet transfer area (QP) along the moving direction of the photoconductor (PR). ), A peeling static eliminator (DTC) arranged in a paper peeling area (Q4) adjacent to the downstream side of the paper transfer area (Q).
P) The paper discharging voltage for peeling the paper (S) having passed through the toner image carrier from the surface of the toner image carrier is applied to the peeling neutralizer (DTC).
(E4 + DTC) having a power supply (E4) for exfoliating electricity to be applied to the device, (A08) Jamming charger control means (C4a) for turning off the charger (CSC) when a jam occurs, (A09) jamming Paper transfer unit (TP) when it occurs
Transfer device control means (C5a) when a jam occurs to turn off
(A010) The photoconductor drive motor (M1) during a period until the surface of the photoconductor (PR) to which the transfer voltage is applied by the paper transfer unit (TP) when the jam occurs, until the surface of the photoconductor (PR) is neutralized by the peeling static eliminator (DTC). (A011) A jam-developing bias control means (C3a) for stopping the developing bias after stopping the photoconductor (PR) when a jam occurs. ),
(A012) After the surface of the photoconductor (PR) to which the transfer voltage is applied by the paper transfer unit (TP) when a jam occurs, the surface of the photoconductor (PR) is neutralized by the peeling neutralizer (DTC), and then the peeling neutralizer (DTC).
Control means for removing the static eliminator when jam occurs (C6
a).

(Operation of the First Invention) In the image forming apparatus of the first invention of the present application having the above-described configuration, a photoconductor rotation driving device (a photoconductor driving motor (M1) and a photoconductor driving circuit (DM1)) is provided. M1 + DM1) rotationally drives the photoconductor (PR). The rotating surface of the photoconductor (PR) is:
A charging area (Q0) facing the charger (CSC), a latent image writing position (Q1) where light corresponding to the image is irradiated, a development area (Q2) facing the development roll (DR), a paper transfer area ( QP) and the sheet peeling area (Q4).
The photoreceptor (PR) is charged when the rotating surface passes through the charging area (Q0), and is charged when the charged surface passes the latent image writing position (Q1). An image is formed, and the electrostatic latent image is developed into a toner image when passing through the development area (Q2). The toner image is transferred to the paper (S) in the paper transfer area (QP). Photoreceptor (PR) in the paper peeling area (Q4)
Peeled from the surface. The charging device (CSC + E2) has a charger (CSC) and a charger power supply (E2), and the charger (CSC) charges the surface of the photoconductor (PR) rotating and moving in the charging area (Q0). . The charger power supply (E2) applies a charging voltage to the charger (CSC).

The developing device (D + DM2 + M2 + E1) includes a developing roll (DR) and a developing roll rotation driving device (DM2
+ M2) and a developing bias power source (E1), and the developing roll rotation driving device (DM2 + M2) rotationally drives the developing roll (DR). The developing bias power supply (E
In 1), a developing bias for developing the electrostatic latent image into a toner image with the toner on the surface of the developing roll (DR) is applied between the developing roll (DR) and the photoconductor (PR).
The developing roll (DR) transports the toner attached to the rotating surface to the developing area (Q2). The paper transfer device (E3 + TP) has a paper transfer device (TP) disposed in the paper transfer area (QP) and a power supply for transfer (E3), and the power supply for transfer (E3) is provided with the toner image. Is applied between the photoconductor (PR) and the paper transfer device (TP). Paper transport device (S
H) conveys the paper (S) stored in the paper feed trays (TR1 to TR3) to the paper transfer area (QP). A peeling static eliminator (E4 + DTC) includes a peeling neutralizer (DTC) disposed in a paper peeling area (Q4) adjacent to the downstream side of the paper transfer area (QP) along the moving direction of the photoconductor (PR). A power supply (E4) for exfoliating and removing the sheet, wherein the power supply (E4) for exfoliating the sheet removes the sheet (S) passing through the sheet transfer area (QP) from the surface of the toner image carrier. Is applied to the peeling static eliminator (DTC).

When a jam occurs, the charger control means (C4a)
Turn off the charger (CSC) when a jam occurs. The jam transfer controller control means (C5a) turns off the paper transfer unit (TP) when a jam occurs. When a paper jam occurs, the photoconductor rotation control means (C1a) controls the time until the surface of the photoconductor (PR) to which the transfer voltage is applied by the paper transfer device (TP) is removed by the peeling static eliminator (DTC) when the paper jam occurs. During the period, the photoconductor drive motor (M1) is rotated and then stopped. Developing bias control means when jam occurs (C3a)
Stops the developing bias after the photosensitive member (PR) is stopped when a jam occurs. When a jam occurs, the control unit (C6a) controls the paper transfer unit (TP) when a jam occurs.
After the surface of the photoreceptor (PR) to which the transfer voltage has been applied in step (a) is neutralized by the peeling neutralizer (DTC), the peeling neutralizer (D) is used.
TC) is turned off. Therefore, when a paper jam occurs, the photoconductor (P) to which the transfer voltage is applied by the paper transfer unit (TP) is applied.
R) The surface passes through the paper peeling area (Q4) and is discharged by the peeling static eliminator (DTC). Therefore, at the time of emergency stop of the image forming apparatus (U), it is possible to enter the next image forming step without leaving a charge having a polarity opposite to the original charge polarity on the photoreceptor (PR). Can be maintained.

(Second Invention) The image forming apparatus of the second invention has the following requirements (B01) to (B012). (B01) The surface which rotates and moves is a charger (CS).
C), a charging area (Q0) facing the image, a latent image writing position (Q1) where light corresponding to the image is irradiated, a developing area (Q2) facing the developing roll (DR), a paper transfer area (QP), And the photoconductor (P) sequentially passing through the photoconductor static elimination area (Q5)
R), wherein the rotating surface is charged when passing through the charging area (Q0), and when the charged surface passes through the latent image writing position (Q1), an electrostatic latent image is formed. The toner image is formed and developed into a toner image when the electrostatic latent image passes through the development area (Q2), and the toner image is transferred to the paper (S) in the paper transfer area (QP). In the photosensitive member static elimination area (Q5), the photosensitive member (P
(R) The photoconductor (PR) whose surface is to be neutralized, (B02) A photoconductor drive motor (M) that rotationally drives the photoconductor (PR)
1) and a photoconductor rotation driving device (M1 + DM1) having a motor driving circuit for driving the photoconductor driving motor (M1);
(B03) A charger (CSC) for charging the surface of the photoconductor (PR) rotating and moving in the charging area (Q0).
A charging device (CSC + E2) having a charger power supply (E2) for applying a charging voltage to the charger (CSC);
(B04) a developing roll (DR) for transporting the toner attached to the rotating surface to the developing area (Q2), a developing roll rotation driving device (DM2 + M2) for rotating the developing roll (DR), A developing device having a developing bias power supply (E1) for applying a developing bias for developing the electrostatic latent image into a toner image with toner on the surface of the roll (DR) between the developing roll (DR) and the photoconductor (PR); (D + DM2 + M2 + E1), (B05) a paper transfer unit (TP) disposed in the paper transfer area (QP), and a transfer voltage for transferring the toner image to the paper (S), the photoconductor (PR) and the paper transfer Paper transfer device (E3 + TP) having a transfer power supply (E3) applied between the transfer units (TP);
(B06) a sheet transport device (SH) for transporting the sheet (S) to the sheet transfer region (QP); (B07) a sheet transfer region (QP) along the moving direction of the photoconductor (PR);
A photoreceptor static eliminator (JC) disposed on the downstream side of the photoreceptor (PR) for discharging the surface of the photoreceptor (PR), and the paper transfer area (QP)
Photoreceptor static eliminator (E6 + JC) having a photoreceptor static eliminator power supply (E6) for applying a photoreceptor static elimination voltage for eliminating the charge potential on the surface of the photoreceptor (PR) that has passed through to the photoconductor neutralizer (JC) , (B08) Charger (CS
C) Turn off when jam occurs.
a), (B09) Jam transfer controller (C5a) for turning off the paper transfer unit (TP) when a jam occurs (B01)
0) The surface of the photoconductor (PR) to which a transfer voltage is applied by the paper transfer unit (TP) when a jam occurs occurs.
C) A photoconductor rotation control means (C1a) at the time of the occurrence of a jam, and the photoconductor (PR) at the time of the occurrence of a jam, in which the photoconductor drive motor (M1) is rotated and then stopped until electricity is removed by C). The developing bias is stopped after the stoppage of the developing operation.
2) When a paper jam occurs, after the surface of the photoconductor (PR) to which the transfer voltage is applied by the paper transfer unit (TP) passes through the photoconductor neutralization area (Q5), the photoconductor neutralizer (JC) is turned off. Control means (C8a) when a jam occurs.

(Operation of the Second Invention) The second invention having the above configuration
The operation of the image forming apparatus of the invention is different from that of the first invention in the following points. The first aspect of the present invention includes a control unit (C6a) for peeling and removing the jam when a jam occurs, and removes and removes the surface of the photoconductor (PR) to which a transfer voltage is applied by the paper transfer unit (TP) when a jam occurs. Electric charge is removed by an electric appliance (DTC). On the other hand, the second invention has a photoreceptor static eliminator control means (C8a) at the time of occurrence of a jam. After the surface of the photoreceptor (PR) to which the transfer voltage is applied at TP) passes through the photoreceptor static elimination area (Q5), the photoreceptor static eliminator (JC) is turned off. Therefore, the surface of the photoconductor (PR) to which the transfer voltage has been applied by the paper transfer unit (TP) when a jam occurs occurs, passes through the photoconductor static elimination area (Q5), and is discharged by the photoconductor static eliminator (JC). You. Therefore, at the time of emergency stop of the image forming apparatus (U), it is possible to enter the next image forming step without leaving a charge having a polarity opposite to the original charge polarity on the photoreceptor (PR). Can be maintained.

(Third Invention) The image forming apparatus of the third invention has the following requirements (C01) to (C013). (C01) The surface which rotates and moves is a charger (CS).
C), a charged area (Q0) facing the image, a latent image writing position (Q1) where light corresponding to the image is irradiated, a developing area (Q2) facing the developing roll (DR), and a paper transfer area (QP).
(PR) sequentially passing through the charging area (Q0), and the charged surface passes through the latent image writing position (Q1). When the electrostatic latent image is formed, the electrostatic latent image is developed into a toner image when passing through the development area (Q2), and the toner image is transferred to the paper (S) in the paper transfer area (QP). The photoconductor (PR), (C02) a photoconductor drive motor (M1) for rotating and driving the photoconductor (PR) and a photoconductor drive circuit (DM1) for driving the photoconductor drive motor (M1). Photoreceptor rotation drive (M1 + DM
1), (C03) a charger (CS) for charging the surface of the photoconductor (PR) rotating and moving in the charging area (Q0)
C) and a charger (CSC + E) having a charger power supply (E2) for applying a charging voltage to the charger (CSC).
2), (C04) a developing roll (DR) for transporting the toner attached to the rotating surface to the developing area (Q2);
A developing roll rotation driving device (DM2 + M2) for rotating the developing roll (DR); and a developing bias for developing the electrostatic latent image into a toner image by toner on the surface of the developing roll (DR). And photoconductor (PR)
A developing device (D + DM2 + M2 + E1) having a developing bias power supply (E1) applied between the paper transfer unit (TP) disposed in the paper transfer area (QP); (E3 + T) having a transfer power supply (E3) for applying a transfer voltage to be transferred to the photosensitive member (PR) and the sheet transfer device (TP).
P), (C06) The sheet (S) is transferred to the sheet transfer area (Q
(C) and (C07) the sheet transfer area (Q) along the moving direction of the photoconductor (PR).
Pre-transfer charger (PTSC) located upstream of P)
And the surface of the photoconductor (PR) and the photoconductor (PR)
A pre-transfer charging potential adjusting device having a pre-transfer charger power supply (E5) for applying a pre-transfer charging potential adjustment voltage for adjusting the charging potential of the toner image formed on the surface to the pre-transfer charger (PTSC); C08) Charger (CS
C) Turn off when jam occurs.
a), (C09) Jam transfer control means for turning off the paper transfer unit (TP) when a jam occurs, (C010) Photoconductor for determining the presence or absence of jam paper adhering to the surface of the photoconductor (PR) Jam detection means (C9), (C011) If the jammed paper does not adhere to the surface of the photoconductor (PR) when a jam occurs, the surface of the photoconductor (PR) to which the transfer voltage is applied by the paper transfer unit (TP) is used. Until the charge is removed by the pre-transfer charger (PTSC), the photoconductor drive motor (M
1) Photoreceptor rotation control means (C1a) for stopping the rotation after rotating the photoconductor, (C012) Development bias control means for the occurrence of a jam that stops the developing bias after stopping the photoconductor (PR) when the jam occurs. (C3a), (C013) When the jammed paper does not adhere to the surface of the photoconductor (PR) at the time of the occurrence of the jam, the surface of the photoconductor (PR) to which the transfer voltage is applied by the paper transfer unit (TP) is moved before the transfer. Charger (PT
SC), the pre-transfer charger (PTS)
Pre-transfer charger control means (C7a) when a jam occurs, which turns off C).

(Operation of the Third Invention)
The operation of the image forming apparatus of the invention is different from that of the first invention in the following points. The first aspect of the present invention includes a control unit (C6a) for peeling and removing the jam when a jam occurs, and removes and removes the surface of the photoconductor (PR) to which a transfer voltage is applied by the paper transfer unit (TP) when a jam occurs. Electric charge is removed by an electric appliance (DTC). On the other hand, the third invention has a photoreceptor jam detecting means (C9) and a pre-transfer charger control means (C7a) when a jam occurs, and the photoreceptor jam detecting means (C9) includes a photoreceptor (PR). ) Determine the presence or absence of jammed paper on the surface.

When a jam occurs, the pre-transfer charger control means (C7a) controls the jammed paper to be transferred to the photosensitive member (P
R) If not attached to the surface, the paper transfer unit (T
After the surface of the photoconductor (PR) to which the transfer voltage is applied in P) passes through the pre-transfer charging area (Q0), the pre-transfer charger (PTSC) is turned off. Therefore, if the jammed paper does not adhere to the surface of the photoconductor (PR) when a jam occurs, the surface of the photoconductor (PR) to which the transfer voltage is applied by the paper transfer unit (TP) is charged in the pre-transfer charging area (Q0). ), And is discharged by the pre-transfer charger (PTSC). Therefore, at the time of emergency stop of the image forming apparatus (U), it is possible to enter the next image forming step without leaving a charge having a polarity opposite to the original charge polarity on the photoreceptor (PR). Can be maintained. When the DC component is made larger than the voltage applied to the normal pre-transfer charger PTSC, it is possible to more effectively prevent the charge having the opposite polarity from remaining. In the third aspect, when the photoconductor jam detecting means (C9) detects that there is jammed paper adhering to the surface of the photoconductor (PR), the rotation of the photoconductor (PR) is immediately stopped. It is possible to

[0023]

(First Embodiment of the First Invention) First
Embodiment 1 of the image forming apparatus of the present invention is characterized in that the first invention satisfies the following requirement (A013). (A013) The developing roll (D
R) a developing roll rotation control means (C2a) for stopping the rotation of the developing roller when a jam occurs;

(Operation of the First Embodiment of the First Invention) In the first embodiment of the image forming apparatus of the first invention having the above configuration, the developing roll rotation control means (C2a) at the time of occurrence of a jam is
Immediately upon the occurrence of a jam, the rotation of the developing roll (DR) is stopped. In this case, since no new developer is conveyed to the development area (Q2), even if the photoconductor (PR) rotates, the surface of the photoconductor (PR) is not developed by the developer.

(Second Embodiment of the First Invention) The second embodiment of the image forming apparatus of the first invention is the same as the first invention or the first invention.
In the first embodiment of the invention, the following requirements (A014),
(A014) The photosensitive member (P) from the charging area (Q0) to the developing area (Q2).
R) When the movement time of the surface is to, and the time from when the charger (CSC) stops when the jam occurs to when the photoconductor (PR) stops is ta, tb = (to-ta), the jam occurs. A recovery-time photosensitive member rotation control means (C1b) for rotating the photosensitive member (PR) for a time tb or more when released.
(A015) a recovery-time developing bias control means (C3b) for applying a DC developing bias to the developing device when the photoconductor rotates during the recovery,

(Operation of the Second Embodiment of the First Invention) In the second embodiment of the image forming apparatus of the first invention having the above-described configuration, the photoconductor rotation control means (C1b) at the time of recovery includes the charging area ( Photoconductor (P) from Q0) to development area (Q2)
R) When the movement time of the surface is to, and the time from when the charger (CSC) stops when the jam occurs to when the photoconductor (PR) stops is ta, tb = (to-ta), the jam occurs. When released, the photoconductor (PR) is rotated for a time tb or more. Recovery bias control means during recovery (C3b)
Applies a DC developing bias to the developing device when the photosensitive member rotates during the recovery. Even if the charging device (CSC) stops immediately when a jam occurs, the surface of the photoconductor (PR) between the charging device (CSC) and the developing device (D) is charged. Until the charged portion of the surface has passed through the development area (Q2), the DC development bias is
If the voltage is not applied between the photoconductor (PR) and the developing roll (DR), the carrier on the developing roll (DR) moves to the surface of the photoconductor (PR). In the second embodiment of the first invention, the DC developing bias is applied until the charged portion on the surface of the photoconductor (PR) at the time of the occurrence of the jam ends to pass through the developing region (Q2). Does not move to the surface of the photoconductor (PR).

(Third Embodiment of the First Invention) The third embodiment of the image forming apparatus of the first invention is the same as the first invention or the first invention.
In the first or second embodiment of the invention, the following requirements (A
(A016) The recovery roll rotation control means (C2) for stopping the rotation of the development roll (DR) when the photoconductor rotates during the recovery.
b).

(Operation of the Third Embodiment of the First Invention) In the third embodiment of the image forming apparatus of the first invention having the above-described configuration, the developing-roll rotation control means (C2b) at the time of recovery includes:
Developing roll (DR) during photoreceptor rotation during recovery
Stop the rotation of. In this case, since no new developer is conveyed to the development area (Q2), even if the photoconductor (PR) rotates, the surface of the photoconductor (PR) is not developed by the developer.

(Embodiment 1 of the Second Invention) Embodiment 1 of the image forming apparatus of the second invention is characterized in that the second invention has the following requirement (B013).
3) A developing roll rotation control means (C2) for stopping the rotation of the developing roll (DR) immediately when a jam occurs.
a),

(Operation of Second Embodiment of the Second Invention) In the first embodiment of the image forming apparatus according to the second invention having the above-described structure, the developing roll rotation control means (C2a) at the time of occurrence of a jam is
Immediately upon the occurrence of a jam, the rotation of the developing roll (DR) is stopped.

Second Embodiment of the Second Invention The second embodiment of the image forming apparatus according to the second invention is the same as the second invention or the second invention.
In the first embodiment of the invention, the following requirements (B014),
(B014) the photosensitive member (P) from the charging area (Q0) to the developing area (Q2).
R) When the movement time of the surface is to, and the time from when the charger (CSC) stops when the jam occurs to when the photoconductor (PR) stops is ta, tb = (to-ta), the jam occurs. A recovery-time photosensitive member rotation control means (C1b) for rotating the photosensitive member (PR) for a time tb or more when released.
(B015) Recovery-time developing bias control means (C3b) for applying a DC developing bias to the developing device when the photosensitive member rotates during the recovery.

(Operation of the Second Embodiment of the Second Invention) In the second embodiment of the image forming apparatus according to the second invention having the above-described structure, the photoconductor rotation control means (C1b) at the time of recovery is controlled by the charging area (C1b). Photoconductor (P) from Q0) to development area (Q2)
R) When the movement time of the surface is to, and the time from when the charger (CSC) stops when the jam occurs to when the photoconductor (PR) stops is ta, tb = (to-ta), the jam occurs. When released, the photoconductor (PR) is rotated for a time tb or more. Recovery bias control means during recovery (C3b)
Applies a DC developing bias to the developing device when the photosensitive member rotates during the recovery.

(Third Embodiment of the Second Invention) The third embodiment of the image forming apparatus of the second invention is the same as that of the second invention or the second invention.
In the first or second embodiment of the invention, the following requirement (B
(B016) a recovery roll rotation control means (C2) for stopping the rotation of the development roll (DR) when the photoconductor rotates during the recovery.
b).

(Operation of the Third Embodiment of the Second Invention) In the third embodiment of the image forming apparatus according to the second invention having the above-described configuration, the developing-roll rotation control means (C2b) at the time of recovery is
Developing roll (DR) during photoreceptor rotation during recovery
Stop the rotation of.

EXAMPLES Next, specific examples (examples) of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.

FIG. 1 is a front sectional view of an image forming apparatus according to a first embodiment of the present invention. In FIG. 1, an image forming apparatus U has a platen glass (transparent platen) PG
A digital copying machine U1 as an image forming apparatus main body having an automatic document feeder (auto document feeder,
ADF) U2. The automatic document feeder U2
Has a document feed tray TG1 on which a plurality of documents G to be copied are placed in an overlapping manner. The plurality of documents G placed on the document feed tray TG1 are configured to sequentially pass through a copy position on the platen glass PG and be discharged to a document discharge tray TG2.

The copying machine U1 has a UI (user interface), an IIT (image input terminal) as an image reading unit, and an IOT as an image recording operating unit sequentially arranged below the platen glass PG.
(Image output terminal) and an IPS (image processing system) provided between the IIT and the IOT. An IIT as an original reading device disposed below the transparent platen glass PG on the upper surface of the copying machine body U1 includes an exposure system registration sensor (platen registration sensor) Sp and an exposure optical system A arranged at a platen registration position (OPT position). have.

The movement and stop of the exposure optical system A are controlled by the detection signal of the exposure system registration sensor Sp, and are always stopped at the home position. In the ADF mode in which copying is performed using the automatic document feeder (auto document feeder) U2, each document that sequentially passes through the copying position on the platen glass PG with the exposure optical system A stopped at the home position. G is exposed. In the platen mode in which the operator places the original G on the platen glass PG by hand and makes a copy, the exposure optical system A moves and scans the original on the platen glass PG while moving. The reflected light from the exposed document G passes through the exposure optical system A,
(Solid-state imaging device). The CCD converts the document reflected light converged on its imaging surface into an electric signal.

The IPS converts a read image signal input from the IIT CCD into a digital image write signal and outputs the digital image write signal to the IOT laser drive signal output device DL. The laser drive signal output device DL outputs a laser drive signal corresponding to the input image data to an ROS (optical writing scanning device, that is, a latent image forming device).

A drum-shaped photoconductor (toner image carrier of the first embodiment) PR disposed below the ROS is indicated by an arrow Y.
Rotate in a direction. The surface of the drum-shaped photoreceptor PR has a charger (charge scorotron) C in a charging area Q0.
After being charged to − (minus) 700 V by the SC, the latent image writing position (Q 1) is exposed and scanned by the laser beam L of the ROS (latent image writing device) at the position Q 1 to −300 V.
Is formed. The formation of a latent image on the drum-shaped photoreceptor PR by the laser beam L is started a predetermined time after the sheet sensor SN1 detects the leading edge of the sheet. The surface of the drum-shaped photoreceptor PR on which the electrostatic latent image has been formed rotates and sequentially passes through the development area Q2 and the paper transfer area QP.

A developing device D for developing the electrostatic latent image in the developing area Q2 conveys a developer containing a toner having a negative polarity and a carrier having a positive polarity to the developing area Q2 by a developing roll DR. , The development area Q2
Is developed into a toner image. The toner image on the surface of the drum-shaped photoreceptor PR is transferred to a pre-transfer charger PTSC.
After passing through the transfer area QP, the potential is adjusted by (pre-transfer scorotron). A paper transfer unit TP that faces the drum-shaped photoconductor PR in the paper transfer area QP is a member that transfers a toner image on the surface of the drum-shaped photoconductor PR onto a sheet S. A transfer voltage having a polarity opposite to the charge polarity of the toner is supplied from the power supply circuit E. The power supply circuit E includes a controller C
Is controlled by

The paper S stored in the paper feed trays TR1 to TR3, or the reversing tray TR used for double-sided recording
The sheet S temporarily stored at 0 is conveyed to the sheet transfer area by the sheet supply path SH1. That is, the paper S in each of the trays TR0 to TR3 is taken out by the pickup roll Rp at a predetermined timing, and
Are separated one by one and transported to the registration roll Rr by the plurality of transport rolls Ra. The sheet S conveyed to the registration roll Rr is conveyed from the pre-transfer sheet guide SG1 to the sheet transfer area QP in synchronization with the movement of the toner image on the drum-shaped photoconductor PR to the sheet transfer area QP. .

The toner image Tn developed on the surface of the drum-shaped photoreceptor PR is transferred to the sheet S by the sheet transfer unit TP to which a transfer voltage having a polarity opposite to the charging polarity of the toner is applied in the sheet transfer area QP. You. After the transfer, the surface of the drum-shaped photoreceptor PR is cleaned by the photoreceptor cleaner CL1 to remove the residual toner, and then the photoreceptor static eliminator JC
And then recharged by the charger CSC.

The sheet S, on which the toner image has been transferred by the sheet transfer unit TP in the sheet transfer area QP, is separated from the discharger DT in the sheet separation area Q4 downstream of the sheet transfer area QP.
The sheet is separated from the surface of the drum-shaped photoreceptor PR by C (detack corotron), and is conveyed to the fixing area QF by the sheet guide SG2 and the sheet conveying belt BH. The sheet S passing through the fixing area QF is heat-fixed by the fixing device F.

A switching gate GT1 disposed downstream of the fixing device F switches the conveying direction of the sheet S passing through the fixing device F to one of the sheet discharging path SH2 and the sheet reversing path SH3. The sheet S conveyed to the sheet discharge path SH2 is discharged to a discharge tray TRh by a plurality of transfer rolls Ra. In the case of double-sided copying, the sheet S on which the toner image on the first side has been transferred is inverted by the sheet reversing path SH3, temporarily stored in the reversing tray TR0 through the sheet recirculating path SH4, and then taken out at a predetermined timing. Then, the toner image is re-sent to the paper transfer area QP, and the toner image is transferred to the second surface. The sheet conveying device SH is composed of the components indicated by the symbols SH1 to SH4, Rp, Rs, Rr, Ra, GT1, and the like.

FIG. 2 is a block diagram of a control portion of the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is a block diagram showing a continuation of the block diagram of FIG. 2 and 3, the controller C includes an I / O (input / output interface) for inputting / outputting a signal to / from an external device and adjusting an input / output signal level, and a program and data for performing necessary processing. ROM (read only memory) stored therein, RAM (random access memory) for temporarily storing necessary data, CPU (central processing unit) for performing processing according to a program stored in the ROM, and The computer is configured by a computer having a clock oscillator and the like, and various functions can be realized by executing a program stored in the ROM.

(Signal Input Elements Connected to Controller C) The controller C detects a UI (user interface), a paper sensor SN1, a paper discharge sensor SN2, and a photoreceptor jam sensor (detects a jammed paper adhering to the photoreceptor surface). Sensor SN3 and other signal input elements. The UI includes a display UIa, a copy start key UIb, a copy number input key UIc, and a numeric keypad U.
Id and the like.

(Control elements connected to the controller C) The controller C is connected to the IPS, the photoconductor driving circuit DM1, the developing roll driving circuit DM2, the power supply circuit E, and other control elements. Outputs an operation control signal. The power supply circuit E includes a developing bias power supply E.
1. Power supply E2 for charger, Power supply E5 for pre-transfer charger, Power supply E3 for transfer, Power supply E4 for stripping and removing electricity, Power supply E6 for photoconductor removing device
Etc. The photoconductor driving circuit DM1 rotationally drives the photoconductor PR via a photoconductor driving motor M1. A photoconductor driving device (DM1 + M1) is constituted by the photoconductor driving circuit DM1 and the photoconductor driving motor M1. The developing roll driving circuit DM2 rotationally drives the developing roll DR of the developing device D via a developing roll driving motor M2. The developing roll driving circuit DM2 and the developing roll driving motor M2 constitute a developing roll rotation driving device (DM2 + M2).

The developing bias power source E1 applies a developing bias voltage to the developing roll DR of the developing device D. As described above, the developing device D uses a developer containing a toner having a negative polarity (−) and a carrier having a positive polarity (+). An electrostatic latent image of 300 V is formed. Therefore, as the developing bias voltage, a DC developing bias DC of -500 V and an AC developing bias AC of +-(plus or minus) 1 kV are applied. Further, the developing bias is applied only with the DC developing bias DC or the DC developing bias D.
The configuration is such that any one of the superimposed applications of the C + AC developing bias AC can be selected and performed. A developing device D having the developing roll DR, a developing roll rotation driving device (DM)
2 + M2) and a developing bias power source E1 constitute a developing device (D + DM2 + M2 + E1).

The charger power supply E 2 applies a charging voltage to a charger CSC (charge corotron). The transfer power source E3 applies a transfer voltage to the sheet transfer device TP. The transfer power source E3 and the sheet transfer device TP constitute a sheet transfer device (E3 + TP). The power supply E for peeling and removing static electricity
Reference numeral 4 applies a charge removing voltage for peeling to the peeling charger DTC. The peeling charge removing device (E4 + DRC) is constituted by the peeling charge removing power source E4 and the peeling charger DTC. The pre-transfer charger power supply E5 is a pre-transfer charger PTSC (pre-transfer).
A transfer pre-transfer charging voltage is applied to a transfer scorotron. The photoreceptor static eliminator power supply E6 is the photoreceptor static eliminator J
Apply static electricity to C.

(Function of Controller C) The controller C has a function of executing a process according to an input signal from the signal output element and outputting a control signal to each control element. That is, the controller C has the following functions. C1: Photoreceptor rotation control signal output means The photoreceptor rotation control signal output means C1 has a photoreceptor rotation control means C1a at the time of occurrence of a jam and a photoreceptor rotation control means C1b at the time of recovery. A photoconductor rotation control signal is output. C1a: Photoreceptor rotation control means when jam occurs: The photoreceptor rotation control means C1a removes electricity from the surface of the photoreceptor PR to which a transfer voltage is applied by the paper transfer unit TP when a jam occurs, by the peeling neutralizer DTC. In this period, the photoconductor driving motor M1 is rotated and then stopped. C1b: Recovery Photoconductor Rotation Control Means Recovery photoconductor rotation control means C1b sets the movement time of the surface of the photoconductor PR from the charging area Q0 to the development area Q2 to to, and after the charger stops when the jam occurs. When the time until the photoconductor PR stops is ta, tb = (to−ta), the photoconductor PR is rotated for the time tb or more when the jam is released.

C2: Development Roll Rotation Control Signal Output Means The development roll rotation control signal output means C2 has a development roll rotation control means C2a when a jam occurs and a development roll rotation control means C2b when a recovery occurs. The developing roll rotation control signal is output to the circuit DM2. C2a: Jam Roll Developing Roll Rotation Control Means: Jam Roll Developing Roll Rotation Control Means C2a removes static electricity from the surface of the photoconductor PR to which the transfer voltage is applied by the paper transfer unit TP when a jam occurs, by the peeling neutralizer DTC. Until the developing roller driving motor M2 is rotated, the motor is stopped. C2b: Recovery roll rotation control means during recovery: Recovery roll rotation control means C2a stops the rotation of the development roll when the photoconductor rotates during recovery. In this case, since no new developer is conveyed to the development area (Q2), even if the photoconductor (PR) rotates, the surface of the photoconductor (PR) is not developed by the developer.

C3: Developing bias control signal output means The developing bias control signal output means C3 has a developing bias control means C3a at the time of occurrence of a jam and a developing bias control means C3b at the time of recovery.
A developing bias control signal is output to 1. C3a: Jam Developing Bias Control Unit The jam developing dev bias control unit C3a stops the developing bias after the photosensitive member PR stops when a jam occurs. C3b: Recovery-time developing bias control means The recovery-time developing bias control means C3b applies a DC developing bias to the developing device when the photoconductor rotates during recovery.

C4: Charger Control Signal Output Means The charger control signal output means C4 has a charger control means C4a when a jam occurs, and outputs a charger control signal to the charger power supply E2. C4a: Jamming Charger Control Unit The jamming charger control unit C4a turns off the charger CSC when a jam occurs.

C5: Sheet Transfer Unit Control Signal Output Unit The sheet transfer unit control signal output unit C5 has a transfer unit control unit C5a when a paper jam occurs, and outputs a transfer unit control signal to the transfer power source E3. C5a: Transfer Device Control Means When a Jam Occurs The transfer device control means C5a when a jam occurs turns off the sheet transfer device TP when a jam occurs.

C6: Exfoliating / eliminator control signal output means The exfoliating / eliminator control signal output means C6 has an exfoliating / eliminator control means C6a at the time of occurrence of a jam.
To output a peeling static eliminator control signal. C6a: Control unit for peeling static eliminator when jam occurs The control unit C6a performs control after the surface of the photoconductor PR to which the transfer voltage is applied by the paper transfer unit when the jam occurs is neutralized by the peeling neutralizer DTC. Then, the peeling static eliminator DTC is turned off.

C7: Pre-Transfer Charger Control Signal Output Means The pre-transfer charger control signal output means C7 outputs a control signal to the pre-transfer charger power supply E5, and outputs the pre-transfer charger PTSC.
(Pre-transfer scorotron) to apply a pre-transfer charging voltage. C8: Photoreceptor static eliminator control signal output means The photoreceptor static eliminator control signal output means C8 outputs a control signal to the photoreceptor static eliminator power supply E6 to apply a pre-transfer charging voltage to the photoreceptor static eliminator JC.

(Operation of the First Embodiment) Next, the operation of the first embodiment having the above-described configuration will be described. FIG. 4 shows the first embodiment.
6 is a time chart of the operation of the charger CSC, the developing bias power supply E1, the sheet transfer device TP, the peeling and removing device DTC, etc. used in the image forming apparatus of FIG. In FIG. 4, when a jam is detected, the charger CSC, the sheet transfer unit TP, the developing roll drive motor M2 and other members are stopped. The stop time is defined as t1. Next, at time t2, the photoconductor driving circuit DM1 is stopped. The photoconductor PR of the first embodiment includes:
280 ms after the photoconductor driving circuit DM1 is stopped
Until ec elapses, it rotates by inertia and stops at time t3. At the time t3, the DC developing bias DC,
And the peeling static eliminator DTC stops.

The elapsed time ta from the time t1 to t3 =
(T3-t1) is the time required for the surface of the photoconductor PR to which the transfer voltage is applied by the paper transfer unit TP to pass through the paper peeling area Q4 before the paper transfer unit TP stops (that is, the peeling and separation). (Time until static elimination is performed by the static eliminator DTC). The paper transfer device TP
The time required for the surface of the photoconductor PR, to which the transfer voltage is applied by the paper transfer device TP, to pass through the paper peeling region Q4 before the paper stops (that is, the time until the charge is removed by the peeling / separating and removing device DTC). If the time is 280 msec or less, the time t2 at which the photoconductor driving circuit DM1 is stopped is:
It is possible to set at the same time as t1, in which case,
The DC developing bias DC and the stop time t3 of the stripping and removing unit DTC can be set to t3 = t1 + 280 msec.

The reason why the DC developing bias DC is maintained in the ON state until the peeling static eliminator DTC is stopped is as follows. That is, when a DC developing bias DC is not applied when the surface of the photoconductor PR charged by the charger CSC passes through the developing area Q2, + (plus) charged carriers on the surface of the developing roll are transferred to the surface of the photoconductor PR. Moving. This is to prevent the movement of the carrier. In addition,
When the DC developing bias DC stops, the charger C
The development area Q is still on the surface of the photoconductor PR charged with SC.
The portion of the surface that has not passed through 2 remains charged. For this reason, in the recovery job executed when the jammed paper is next removed and the image forming apparatus U starts operating, the charged portion of the photoconductor PR surface portion remains charged until it passes the developing area Q2. The DC developing bias DC needs to be turned on.

FIG. 5 is a diagram showing a state in which jam recovery (when jammed paper is removed) of the charger CSC, the developing bias power supply E1, the paper transfer unit TP, the peeling eliminator DTC, and the like used in the image forming apparatus of the first embodiment. It is a time chart of operation.
In FIG. 5, when the jammed paper is removed and the door of the image forming apparatus U is closed at time t4, the door closing is detected by the door open / close detection sensor SN4. At time t5, which is slightly delayed from the time t4, the photosensitive member PR drive circuit D
M1 and DC development bias DC (Development DC bias)
Turns on. At time t6 after a lapse of time tb = to-ta from time t5, the photoconductor drive circuit and the developing DC bias are turned off. Note that the developing roll drive motor M2 remains off. Even if the charger CSC is stopped immediately when a jam occurs, the surface of the photoconductor PR between the charger CSC and the developing device D is charged, so that the charged portion of the surface of the photoconductor PR passes through the developing area Q2. Until the completion, the DC developing bias is not applied between the photoconductor PR and the developing roll DR, so that the carrier on the developing roll DR moves to the surface of the photoconductor PR. Therefore, as shown in the time chart at the time of the jam recovery shown in FIG. 5, the charged portion of the surface of the photoconductor PR at the time of the occurrence of the jam is completely passed through the developing region Q2 (that is, the time tb = to-ta is not longer than the time tb = to-ta). Until elapse), the DC developing bias is applied so that the carry does not move to the surface of the photoconductor PR.

FIG. 6 is a flowchart of the jam stop processing of the image forming apparatus according to the first embodiment of the present invention, and is a flowchart corresponding to the time chart of FIG. FIG.
The processing of each ST (step) in the flowchart of (1) is performed according to a program stored in the ROM of the controller C. The jam stop process shown in FIG. 6 is started when the power is turned on. In FIG. 6, when the jam stop processing is started, in ST1 (step 1), it is determined whether or not the start key is turned on.
Is repeatedly executed. If yes (Y), the process moves to ST2. In ST2, it is determined whether a jam has occurred.
If no (N), the process moves to ST3. In ST3, it is determined whether or not the job has been completed. If yes (Y), the process returns to ST1, and if no (N), the process returns to ST2. In the case of YES (Y) in ST2, the process moves to ST4. S
At T4, the fact that a jam has occurred is displayed on the display unit.

Next, the following processing is performed in ST5. (1) The charging device CSC, the transfer device TC, the developing roll driving circuit DM2, the AC developing bias AC and the like are stopped. (2) Set (ta-280) msec (see FIG. 4) to the timer TM. Next, in ST6, it is determined whether or not the timer TM has expired. If no (N), ST6 is repeatedly executed. If yes (Y), the process moves to ST7. The following processing is performed in ST7. (1) The photoconductor driving circuit DM1 is turned off. (2) Set 280 msec in the timer TM. Next, in ST8, the timer TM determines whether or not the time has expired. If no (N), ST8 is repeatedly executed. If yes (Y), the process moves to ST9.

The following processing is performed in ST9. (1) The application of the developing DC bias DC is stopped. (2) Stop the peeling charger DTC. Next, a jam recovery process is performed in ST10. This subroutine of ST10 is shown in FIG.

FIG. 7 is a flowchart of a subroutine of the recovery process in ST10 of FIG. 6, and is a flowchart corresponding to the time chart of FIG. In ST11 of FIG. 7, it is determined whether the door has been opened or the paper tray has been pulled out. ST if no (N)
Repeat step 11. If yes (Y), the process moves to ST12. In ST12, it is determined whether all the doors are closed or all the trays are stored. If no (N), ST12 is repeated. If yes (Y), the process moves to ST13. In ST13, it is determined whether or not jam paper exists (is left). If yes (Y), the process moves to ST11. If no (N), the process moves to ST14.

The following processing is performed in ST14. (1) Turn on the photoconductor drive circuit DM1. (2) Turn on the DC developing bias DC. (3) The time tb = (to-ta) (see FIG. 5) is set in the timer TM. At this time, the developing roll drive motor M2 remains off. Developing roll D during photoreceptor rotation during recovery
When the rotation of R is stopped, no new developer is conveyed to the development area Q2, so that even if the photoconductor PR rotates, the surface of the photoconductor PR is not developed by the developer. Next, in ST15, the timer TM determines whether or not the time is up.
If no (N), ST15 is repeated. If yes (Y), the process moves to ST16. The following processing is performed in ST16. (1) The photoconductor driving circuit DM1 is turned off. (2) Turn off the DC developing bias DC. Next, the process returns to ST11.

In the first embodiment, when a paper jam occurs, the surface of the photoconductor PR charged by the paper transfer unit TP to the positive (+) opposite to the normal charging polarity of the photoconductor PR (−) is removed by the peeling and removing unit DTC. As a result, during the emergency stop of the image forming apparatus U, it is possible to enter the next image forming step without leaving a charge having a polarity opposite to the original charge polarity on the photoreceptor PR, and maintain good image quality. can do.

(Embodiment 2) FIG. 8 is a block diagram of a control portion of an image forming apparatus according to Embodiment 2 of the present invention.
FIG. 4 is a view corresponding to FIG. FIG. 9 is a time chart at the time of jam stop processing of a charger, a developing bias power supply, a sheet transfer device TP, a peeling static eliminator DTC, a photoconductor neutralizing device JC, and the like used in the image forming apparatus U according to the second embodiment of the present invention. 5 is a diagram corresponding to FIG. 4 of the first embodiment. Note that the second embodiment
In the description, the same reference numerals are given to the components corresponding to the components of the first embodiment, and the detailed description thereof will be omitted. In the first embodiment, the surface of the photoconductor PR charged by the paper transfer unit TP at the time of a jam is discharged by the peeling static eliminator DTC, whereas in the second embodiment, the charge is removed by the photoconductor eliminator JC. Although the third embodiment is different from the first embodiment in the point, it is configured similarly to the first embodiment in other points. Therefore, the second embodiment differs from the first embodiment in the block diagram, time chart, and flowchart of the control unit.

In FIG. 8, the control unit C6a for stripping and removing a jam when a jam occurs shown in FIG. 3 of the first embodiment is omitted. Instead, the control unit for outputting a control signal for a photosensitive drum static eliminator C8 has the following functions. ing. C8: Photoreceptor static eliminator control signal output means The photoreceptor static eliminator control signal output means C8 has a photoreceptor static eliminator control means C8a when a jam occurs, and outputs a control signal to the photoreceptor static eliminator power supply E6. To apply a neutralization voltage to the photoconductor neutralizer JC. C8a: Photosensitive member static eliminator control means when a jam occurs The photoconductor static eliminator control means C8a controls the surface of the photoconductor PR to which the transfer voltage is applied by the paper transfer device TP when the jam occurs, by the photoconductor static eliminator JC. After static elimination,
The photoreceptor static eliminator JC is turned off.

In FIG. 4 of the first embodiment, the stop time of the photosensitive member static eliminator JC at the time of jam is set to the time of occurrence of jam t1,
The stop time of the peeling static eliminator DTC is set to t3. However, in FIG.
The stop time of C is defined as t3, and the stop time of the peeling static eliminator DTC is defined as jam occurrence t1.

In the second embodiment, when a paper jam occurs, the surface portion of the photoconductor PR charged by the paper transfer unit TP to + (plus) opposite to the normal charging polarity-(minus) of the photoconductor PR is removed by the photoconductor neutralizer. Since the charge is removed by the JC, when the image forming apparatus U is stopped in an emergency, it is possible to enter the next image forming process without leaving a charge having a polarity opposite to the original charge polarity on the photoreceptor PR. Can be maintained.

(Embodiment 3) FIG. 10 is a block diagram of a control part of an image forming apparatus according to a third embodiment of the present invention, and corresponds to FIG. 3 of the first embodiment. In the description of the third embodiment, components corresponding to the components of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. In the first embodiment, the surface of the photoreceptor PR charged by the paper transfer unit TP at the time of the jam is discharged by the peeling discharger DTC, whereas in the third embodiment, the charge is removed by the pre-transfer charger PTSC. This is different from the first embodiment in the point. The surface of the photoconductor PR charged to + (plus), which is the opposite of the original charge polarity of the paper transfer unit TP, to-(minus), is removed by the pre-transfer charger PTSC until the charge is removed. It is necessary to rotate the PR approximately one revolution. In this case, if the jammed paper adheres to the surface of the photoconductor PR, the jammed paper may be caught by the photoconductor cleaner CL1 and crumpled. Therefore, in the third embodiment, the jammed paper adsorbed on the surface of the photoconductor PR is detected by the photoconductor jam SN3, and only when the jammed paper is not detected, the photosensitive paper charged by the paper transfer unit TP at the time of the jam is detected. The surface of the body PR is neutralized by the pre-transfer charger PTSC.

In FIG. 10, the control unit C6a for separating and removing a jam when a jam occurs shown in FIG. 3 of the first embodiment is omitted, and instead, the pre-transfer charger control signal output unit C7 has the following functions. ing. C7: Pre-Transfer Charger Control Signal Output Means The pre-transfer charger control signal output means C7 has a pre-transfer charger control means C7a when a jam occurs, and outputs a control signal to the pre-transfer charger power supply E5. A pre-transfer charging voltage is applied to the pre-transfer charger PTSC. C7a: Pre-Transfer Charger Control Means When a Jam Occurs The pre-transfer charger control means C7a when jammed is detected by the sheet transfer unit TP to have the opposite polarity only when no jammed paper is detected when a jam occurs. The surface of the photoconductor PR is removed by the pre-transfer charger PTSC. Then, when a paper jam occurs, the surface of the photoconductor PR to which the transfer voltage has been applied by the paper transfer device TP is discharged by the pre-transfer charger PTSC, and then the pre-transfer charger P
Turn off TSC.

C9: Photoconductor Jam Detection Means The photoconductor jam detection means C9 detects the presence or absence of jammed paper adsorbed on the surface of the photoconductor PR by the detection signal of the photoconductor jam sensor SN3 when a jam occurs.

In FIG. 4 of the first embodiment, the stop time of the photosensitive member static eliminator JC at the time of jam is set to the time of occurrence of jam t1,
Although the stop time of the peeling static eliminator DTC is set to t3, in FIG. 11 of the third embodiment, the stop time of the pre-transfer charger PTSC at the time of jam is t3, and the stop time of the peeling static eliminator DTC is jam time t1. I have.

FIG. 12 is a flowchart of the jam stop processing according to the third embodiment, and corresponds to FIG. 6 of the first embodiment. The flowchart of FIG. 12 shows that S6 is set before ST6 and ST8.
This is different from the flowchart of FIG. 6 of the first embodiment in that the photoconductor jam detection processing of T5 'and ST7' is performed. The following processing is performed in ST9 '. (1) The application of the developing DC bias DC is stopped. (2) Turn off the pre-transfer charger PTSC. In other respects, the flowchart of FIG.
This is the same as FIG.

FIG. 13 shows a subroutine of ST5 'and ST7' in FIG. It is determined whether or not a photoconductor jam has been detected in ST31 of FIG. If no (N), the process returns to the main routine. If yes (Y), the process moves to ST32. The following processing is performed in ST32. (1) The photoconductor driving circuit DM1 is turned off. (2) Stop applying the developing DC bias DC. (3) Stop the pre-transfer charger PTSC.

In the third embodiment, when a paper jam occurs, the surface portion of the photoconductor PR charged by the paper transfer unit TP to + (plus) opposite to the normal charging polarity of the photoconductor PR-(minus) is a pre-transfer charger. Since the charge is removed by the PTSC, during the emergency stop of the image forming apparatus U, it is possible to enter the next image forming step without leaving a charge having a polarity opposite to the original charge polarity on the photoreceptor PR. Can be maintained.

(Modifications) Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, but falls within the scope of the present invention described in the appended claims. Thus, various changes can be made. Modified embodiments of the present invention will be exemplified below. (H01) The present invention is also applicable to an image forming apparatus using a photosensitive belt.

[0080]

The above-described image forming apparatus of the present invention has the following effects. (E01) During an emergency stop of the image forming apparatus, it is possible to enter the next image forming step without leaving a charge having a polarity opposite to the original charge polarity on the photoreceptor, thereby maintaining good image quality.

[Brief description of the drawings]

FIG. 1 is a front sectional view of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram of a control portion of the image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a continuation of the block diagram of FIG. 2;

FIG. 4 shows a charger CSC, a developing bias power supply E1, and a sheet transfer device T used in the image forming apparatus of the first embodiment.
6 is a time chart of the operation when a jam occurs in P, the peeling static eliminator DTC, and the like.

FIG. 5 is a diagram illustrating a charger CSC, a developing bias power source E1, and a sheet transfer unit T used in the image forming apparatus according to the first embodiment.
6 is a time chart of an operation at the time of jam recovery (when jammed paper is removed) of P, a peeling static eliminator DTC and the like.

FIG. 6 is a flowchart of a jam stop process according to the first embodiment of the image forming apparatus of the present invention.

FIG. 7 is a flowchart of a subroutine of a recovery process in ST10 of FIG. 6;

FIG. 8 is a block diagram of a control portion of the image forming apparatus according to the second embodiment of the present invention.

FIG. 9 illustrates a charger, a developing bias power supply, and a sheet transfer unit T used in the image forming apparatus U according to the second embodiment of the present invention.
FIG. 6 is a time chart at the time of jam stop processing of P, the peeling static eliminator DTC, etc., corresponding to FIG. 4 of the first embodiment.

FIG. 10 is a third embodiment of the image forming apparatus of the present invention.
FIG. 4 is a block diagram of a control part corresponding to FIG. 3 of the first embodiment.

FIG. 11 is a diagram illustrating a state in which jams of a charger, a developing bias power supply, a sheet transfer unit TP, a peeling and removing unit DTC, a pre-transfer charger PTSC, and the like used in the image forming apparatus U according to the third embodiment of the present invention are stopped. FIG. 6 is a time chart corresponding to FIG. 4 of the first embodiment.

FIG. 12 is a third embodiment of the image forming apparatus of the present invention.
9 is a flowchart of a jam stop process.

FIG. 13 is a flowchart of a subroutine of photoconductor jam detection processing in ST5 'and ST7' of FIG.

[Explanation of symbols]

C1a: photoconductor rotation control means at the time of occurrence of a jam; C1b: photoconductor rotation control means at the time of recovery; C2a: development roll rotation control means at the time of jam occurrence; C2b: development roll rotation control means at the time of recovery; C3b ... development bias control means at the time of recovery ,
C3a: developing bias control means when a jam occurs; C4a: charging device control means when a jam occurs; C5a: transfer device control means when a jam occurs; C6a: peeling static eliminator control means when a jam occurs; C7a
... Control means for pre-transfer charger when a jam occurs, C8a ... Control means for a photoreceptor static eliminator when a jam occurs, C9 ... Photoreceptor jam detecting means, CSC ... Charger, DM1 ... Photoconductor drive circuit, DR ...
The developing roll, DTC: peeling static eliminator, E1: developing bias power source, E2: charging device power source, E3: transfer power source, E4
... power supply for peeling and removing electricity, E5 ... power supply for pre-transfer charger, E6 ... power supply for photoreceptor charge remover, JC ... photoreceptor charge remover, M1 ... photoreceptor drive motor, PR ... photoreceptor, PTSC ... pre-transfer charger
Q0: charging area, Q1: latent image writing position, Q2: developing area,
QP: paper transfer area, Q4: paper peeling area, Q5: photosensitive member static elimination area, S: paper, SH: paper transport device, TP: paper transfer device, TR1 to TR3: paper feed tray, (CSC + E2) ...
Charging device, (M1 + DM1) photoconductor rotation driving device, (D
M2 + M2) ... Developing roll rotation drive device, (D + DM2 +
M2 + E1): developing device, (E3 + TP): paper transfer device,
(E4 + DTC) ... Electrification remover, (E5 + PTSC) ...
Pre-transfer charge potential adjusting device, (E6 + JC): photoreceptor static eliminator,

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 21/14 G03G 21/00 372 F term (Reference) 2H003 BB11 CC01 DD03 EE12 2H027 DC14 ED02 ED03 ED09 ED17 ED24 ED26 EE02 EE03 EE04 EE05 EK06 EK09 ZA01 ZA10 2H032 AA02 CA04 CA12 CA13 DA03 DA18 DA24 DA27 DA28 2H072 AA02 AB22 2H073 BA01 BA02 BA09 BA13 BA22 BA41

Claims (9)

[Claims] 1. An image forming apparatus having the following requirements (A01) to (A012): (A01) Irradiation with light corresponding to an image, a charged area whose rotating surface faces a charger. A latent image writing position, a photoreceptor sequentially passing through a developing area facing a developing roll, a sheet transfer area, and a sheet peeling area, wherein the rotating surface is charged when passing through the charging area. Forming an electrostatic latent image when the charged surface passes through the latent image writing position; developing the electrostatic latent image into a toner image when passing the developing region; Transferred to the paper in the transfer area,
(A02) a photoconductor having a photoconductor driving motor for rotating the photoconductor and a motor driving circuit for driving the photoconductor driving motor; Rotary drive, (A0
3) a charging device having a charger for charging the surface of the photoreceptor rotating in the charging region, and a power supply for a charger for applying a charging voltage to the charger; (A04) removing toner adhering to the rotating surface; A developing roller for transporting the developing roller to the developing area; a developing roller rotation driving device for rotating the developing roller; and a developing bias for developing the electrostatic latent image into a toner image with toner on the surface of the developing roll. A developing device having a developing bias power supply applied between the photoconductor and the paper transfer device; and a paper transfer device disposed in the paper transfer region, and a transfer voltage for transferring the toner image onto paper. (A06) a paper transfer device having a transfer power supply applied between the paper transfer device and (A06) a paper transport device for transporting the paper accommodated in the paper tray to the paper transfer region; A peeling static eliminator disposed in a paper peeling area adjacent to a downstream side of the paper transferring area along a moving direction of the light body, and a paper neutralizing means for peeling a sheet passing through the paper transferring area from the surface of the toner image carrier (A08) Jamming charger control means for turning off a charger when a jam occurs, and (A09) turning off a transfer unit when a jam occurs. (A)
010) When the jam occurs, the photosensitive member drive motor is rotated and then stopped until the surface of the photosensitive member, to which the transfer voltage is applied by the paper transfer unit, is discharged by the peeling static eliminator. Control means, (A011) a developing bias control means at the time of jam occurrence for stopping the developing bias after stopping of the photosensitive member at the time of jam occurrence, (A012)
Means for controlling a peeling static eliminator to turn off the peeling static eliminator after the surface of the photoreceptor to which the transfer voltage has been applied by the paper transfer unit is neutralized by the peeling neutralizer when the jam occurs. 2. The image forming apparatus according to claim 1, further comprising the following requirement (A013): (A013) a developing roll rotation control unit for stopping the rotation of the developing roll immediately when a jam occurs; , 3. The image forming apparatus according to claim 1, further comprising the following requirements (A014) and (A015): (A014) Movement of the surface of the photosensitive member from the charging area to the developing area. The time is to, and the time from when the charger stops when the jam occurs to when the photosensitive member stops is ta, tb =
When (to-ta) is set, when the jam is released,
(A015) Recovery-time photoconductor rotation control means for rotating the photoconductor for time tb or more; (A015) Recovery-time development bias control means for applying a DC developing bias to a developing device when the photoconductor rotates during the recovery; 4. The image forming apparatus according to claim 1, wherein the image forming apparatus satisfies the following requirement (A016): (A016) The rotation of the developing roller is stopped when the photosensitive member rotates during the recovery. Recovery roller rotation control means during recovery. 5. An image forming apparatus having the following requirements (B01) to (B012): (B01) Irradiation with light corresponding to an image, a charged area whose rotating surface faces a charger. A latent image writing position, a developing area opposed to a developing roll, a paper transfer area, and a photoconductor sequentially passing through a static elimination area, wherein the rotating surface is charged when passing through the charging area; An electrostatic latent image is formed when the charged surface passes the latent image writing position, and is developed into a toner image when the electrostatic latent image passes through a development area. (B02) a photoconductor driving motor for rotating the photoconductor, and a photoconductor driving motor for driving the photoconductor driving motor; Having a motor drive circuit Photoreceptor rotation drive, (B03)
A charging device having a charger for charging the surface of the photoreceptor rotating in the charging area, and a power supply for a charger for applying a charging voltage to the charger; (B04) developing the toner adhered to the rotating surface on the developing device; A developing roll that conveys the developing roller to a region, a developing roll rotation driving device that rotationally drives the developing roll, and a developing bias that develops the electrostatic latent image into a toner image using toner on the developing roll surface. (B05) a paper transfer device disposed in the paper transfer area, and a transfer voltage for transferring the toner image to paper between the photoconductor and the paper transfer device. (B06) a paper transport device for transporting the paper to the paper transfer area, (B07) along a moving direction of the photoconductor A photoreceptor static eliminator disposed downstream of the sheet transfer area to eliminate charge on the surface of the photoreceptor; and a photoreceptor static eliminator for removing charge potential on the surface of the photoreceptor passing through the sheet transfer area. Photoreceptor static eliminator having a power supply for the photoreceptor static eliminator applied to the device, (B08) a charger control means for turning off the charger when a jam occurs, and (B09) a jam for turning off the transfer device when a jam occurs. (B010) When a paper jam occurs, the photoconductor drive motor is rotated during a period until the surface of the photoconductor to which the transfer voltage is applied by the paper transfer unit is neutralized by the photoconductor neutralizer. (B011) Developing bias control means for stopping the developing bias after stopping the photoconductor when a jam occurs, and (B012) When a jam occurs After said applying photosensitive member surface transfer voltage in paper transfer unit has passed the neutralization region, the jam occurrence photoreceptor discharger control means for turning off the photoreceptor discharger. 6. The image forming apparatus according to claim 5, further comprising the following requirement (B013): (B013) a developing roll rotation control unit for stopping the rotation of the developing roll immediately after the occurrence of a jam. . 7. The image forming apparatus according to claim 5, wherein the following requirements (B014) and (B015) are provided: (B014) Movement of the surface of the photoconductor from the charging area to the developing area. The time is to, and the time from when the charger stops when the jam occurs to when the photosensitive member stops is ta, tb =
When (to-ta) is set, when the jam is released,
(B015) A recovery-time developing bias control means for applying a DC developing bias to the developing device when the photoconductor rotates during the recovery. 8. The image forming apparatus according to claim 5, wherein the image forming apparatus satisfies the following requirement (B016): (B016) The rotation of the developing roller is stopped when the photoconductor rotates during the recovery. Recovery roller rotation control means during recovery. 9. An image forming apparatus having the following requirements (C01) to (C013): (C01) Irradiation with light corresponding to an image, a charged area whose rotating surface faces a charger. A latent image writing position, a developing area opposed to a developing roll, and a photoconductor sequentially passing through a paper transfer area, wherein the rotating surface is charged when passing through the charging area, and An electrostatic latent image is formed when the surface passes through the latent image writing position, and the electrostatic latent image is developed into a toner image when the electrostatic latent image passes through a development area. The photoreceptor transferred to
(C02) a photoreceptor rotation drive device having a photoreceptor drive motor for rotating the photoreceptor and a motor drive circuit for driving the photoreceptor drive motor; and (C03) a photoreceptor surface rotating and moving in the charging area. A charger for charging;
A charging device having a charger power supply for applying a charging voltage to the charger; (C04) a developing roll for transporting toner adhered to a rotatable surface to the developing area; and a developing roll rotating for rotating the developing roll. A developing device comprising: a driving device; and a developing bias power supply for applying a developing bias for developing the electrostatic latent image into a toner image with the toner on the developing roll surface between the developing roll and the photoconductor.
05) a paper transfer device having a paper transfer device disposed in the paper transfer area, and a transfer power supply for applying a transfer voltage for transferring the toner image to the paper between the photoconductor and the paper transfer device; (C06) A sheet conveying device for conveying the sheet to the sheet transfer area; (C07) a pre-transfer charger arranged upstream of the sheet transfer area along a moving direction of the photoconductor; A pre-transfer charging potential adjustment device having a pre-transfer charging device power supply for applying a pre-transfer charging potential adjustment voltage for adjusting the charging potential of the toner image formed on the body surface to the pre-transfer charger, (C08) when a jam occurs A charger control means at the time of a jam occurrence for turning off the charger;
(C09) transfer device control means for turning off the transfer device when a jam occurs; (C010) photoreceptor jam detection means for determining the presence or absence of jammed paper adhering to the photoreceptor surface;
(C011) If the jammed paper does not adhere to the surface of the photoreceptor when a jam occurs, the photoreceptor is not charged until the surface of the photoreceptor to which the transfer voltage is applied by the paper transfer unit is removed by the pre-transfer charger. Photoreceptor rotation control means at the time of jam occurrence for stopping the drive motor after rotation, (C012) Development bias control means at the time of jam occurrence for stopping the developing bias after the stop of the photoreceptor at the time of jam occurrence, (C013)
If the jammed paper does not adhere to the photoreceptor surface at the time of the occurrence of the jam, the photoreceptor surface to which the transfer voltage has been applied by the paper transfer unit is discharged by the pre-transfer charger, and then the pre-transfer charger is turned off. Pre-transfer charger control means when a jam occurs.