JP4472438B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus having a set detection mechanism for a recording medium transfer apparatus.

The prior art will be described with reference to FIG.
Conventionally, in the electrophotographic system, a technique is known in which a reference pattern is created on the second image carrier 10 for toner density control, the reflection density is detected, and the toner density is adjusted. The sensor 40 for detecting the reflection density loses its function when it is contaminated with toner, so that the toner is less likely to be contaminated. It is often placed at a position behind (the area between).

  In such a configuration, when detecting the reflection density of the reference pattern, the recording medium transfer device 30 needs to be separated from the second image carrier. This is because the pattern is disturbed or taken away by the recording medium transfer means 30 if the contact is maintained. If the pattern is removed, the machine recognizes that the toner density is low, and a large amount of toner is mistakenly supplied, resulting in a problem that the inside of the machine becomes extremely dirty.

  For example, in the invention described in Patent Document 1, when a reference toner image is passed over a photoconductor provided with a transfer roller, the transfer roller is exposed before the reference toner image reaches a position where the photoconductor and the transfer roller face each other. The transfer roller contacting / separating means is controlled so that the transfer roller is brought into contact with the photoconductor after the reference toner image has passed through the facing position. Furthermore, in the present invention, a shutter is provided in the vicinity of the toner concentration detection device in order to prevent dirt from adhering to the toner concentration detection device, and this opening and closing is performed in conjunction with the contact and separation of the transfer roller. A mechanism has been proposed.

JP 7-234595 A

  However, regarding the contact detection of the recording medium transfer means in FIG. 1 or the transfer roller in Patent Document 1, no mechanism has been proposed that works in conjunction with other parts, and a special sensor is used for this. It was done.

In view of the above circumstances, an object of the present invention is to provide an image forming apparatus having an inexpensive configuration by performing set detection of a recording medium transfer apparatus without using a special sensor.
It is another object of the present invention to provide an image forming apparatus having a stable operating condition by dealing with malfunctions due to an abnormal state of the density detection device and a set failure of the recording medium transfer device.

The features of the present invention, which is a means for solving the above problems, are listed below.
1. The image forming apparatus of the present invention is provided on an image carrier, a recording medium transfer device for transferring a toner image on the image carrier to a recording medium, and a position facing the image carrier. In the image forming apparatus, comprising: a toner density detection device that detects a toner image of the toner; and a shutter device that protects a detection surface of the toner density detection device, the recording medium transfer device is in contact with and separated from the image carrier. The shutter device includes a window portion and a shutter that is movably provided between the image carrier and the toner density detection device, and the recording medium transfer device includes the image carrier. In the state of contact with the toner density detection device, the detection surface of the toner density detection device is covered with the shutter, and when the recording medium transfer device is separated from the image carrier, the shutter moves and passes through the window portion. in front When the toner density detection device enables detection of the toner image on the image carrier, and when the recording medium transfer device moves in a direction in contact with the image carrier and in a direction away from the image carrier. The toner density detection device detects a set state of the recording medium transfer device by performing an operation of detecting a toner image on the image carrier.
2. The image forming apparatus according to the present invention includes: In the invention described in item 1, the shutter is moved when a part of the recording medium transfer device pushes the shutter against the urging force of the urging means.
3. In addition, the image forming apparatus of the present invention includes: In the invention described in claim 1, the shutter device has an urging means for urging the shutter, and a part of the recording medium transfer device pushes the shutter against the urging force of the urging means. The shutter moves.
4). In addition, the image forming apparatus of the present invention includes: In the invention described in (1), a part of the recording medium transfer device is located on a side opposite to the fulcrum with respect to a position where the image carrier and the recording medium transfer device abut.
5). The image forming apparatus according to the present invention includes: Or 4. In any of the inventions, a plurality of toner concentration detection devices are provided.
6). Further, the image forming apparatus of the present invention is provided with 5. In the invention described in (1), when the set detection results by the plurality of toner concentration detection devices do not match during the contact / separation operation of the recording medium transfer device, it is determined that the toner concentration detection device is abnormal. It shall be the feature.
7). The image forming apparatus according to the present invention includes: Or 6. In the invention according to any one of the above, the image carrier is an intermediate transfer belt that is supported by a plurality of rollers and configured to be movable in a predetermined direction. The image forming apparatus further includes a plurality of photosensitive members and a toner image on the plurality of photosensitive members sequentially transferred to the intermediate transfer belt. 1 transfer means.
8). The image forming apparatus according to the present invention includes: Or 7. In any one of the inventions, the toner density detection device detects a toner density adjustment pattern.

  Therefore, the image forming apparatus according to the present invention can detect the set state of the recording medium transfer apparatus without using a special sensor by the means to solve the above problem, and thus can reduce the manufacturing cost. It can be done.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 shows an example of an image forming apparatus to which the present invention is applied. A cleaning device 2, a charging device is mounted on the outer periphery of a first image carrier (photosensitive member) 1 that is rotatably supported and rotates in the direction of an arrow. A device 3 and a developing device 5 are provided.
There are four first image carriers (photoconductors) 1 (a, b, c, d), but the image forming parts provided in the periphery are the same, and the color material (the developing device 5 handles) The color of the toner is different. In the first image carrier 1 of the present invention, an organic semiconductor layer, which is a photoconductive substance, is provided on the surface of an aluminum cylinder having a diameter of about 30 to 100 mm. It is in contact with an image carrier (intermediate transfer belt) 10. The first image carrier 1 may be a belt-shaped one.
The second image carrier 10 is supported and stretched between the rotating rollers 11 and 12 so as to be movable in the direction of the arrow. On the back side (inside the loop), the first transfer means 20 is the first transfer unit 20. In the vicinity of the image carrier 1. Further, a second image carrier 10 cleaning device 25 is disposed outside the belt loop of the second image carrier 10, so that the surface of the second image carrier 10 after the transfer is transferred from the second image carrier 10. Unnecessary toner remaining on the toner can be wiped off. The second image carrier (intermediate transfer member) 10 according to the present invention is a belt having a base of resin film or rubber having a base thickness of 50 μm to 600 μm, and can transfer toner from the first image carrier 1. The resistance value is as follows.

On the other hand, a recording medium transfer device 30 is provided on the right side of the image forming apparatus shown in FIG. 1, and the recording medium transfer device 30 can be separated from the second image carrier 10. As a result, the separation operation is a rotational movement in the direction of (a) in the figure, with the fulcrum 31 of the recording medium transfer device 30 as the center.
Further, a toner density detection device 40 is disposed downstream from the contact position between the second carrier 10 and the recording medium transfer device 30, so that the transfer paper is not passed at the end of the job or before the start of the job. Sometimes, a plurality of toner images having different image densities are detected to optimize the image forming conditions.

Incidentally, when dirt such as toner adheres to the detection surface (lower surface in the drawing) of the toner concentration detection device 40, there is a problem that the detection accuracy is deteriorated and adversely affects the image density.
In the present invention, in order to solve this problem, a shutter 50 is provided other than necessary to prevent the toner concentration detection device 40 from being attached to dirt, thereby preventing dirt such as scattered toner from adhering.
When the density detection pattern is transferred to the second image carrier 10 for adjusting the toner density, the recording medium transfer device 30 is separated to prevent the toner density adjustment pattern from being touched. When the recording medium transfer device 30 performs the separation operation, the shutter 50 moves in the direction (c) in the drawing by the tension of the spring 60, and the detection surface of the toner concentration detection device 40 is moved to the second position from the shutter window. The toner density detection pattern transferred to the image carrier 10 can be detected. When the recording medium transfer device 30 performs a contact operation with the second image carrier 10, the shutter 50 is interlocked. Thus, the detection surface of the toner density detection device 40 is protected by the shutter 50.

FIG. 2 is an example showing a change in the output value from the toner concentration detection device 40 according to the present invention. More specifically, the shutter 50 changes the detection surface of the toner concentration detection device 40 from the closed state to the open state. The state of the change of an output value at the time of shifting to a closed state is shown. When the shutter 50 is in the closed state, the output value is 0 ( V ), and when the shutter 50 shifts to the open state, the output value changes to 5 ( V ). Further, when the shutter 50 shifts to the closed state, the output value changes to 0 ( V ) again.

  The present invention utilizes the phenomenon described above that the output value from the toner density detection device 40 differs between the closed state and the open state of the shutter 50. That is, in the mechanism in which the shutter 50 of the toner density detection device 40 operates in conjunction with the contact / separation operation of the recording medium transfer device 30, the toner density detection device 40 is operated during the contact / separation operation of the recording medium transfer device 30. Then, it is determined from the output value of the toner density detection device 40 whether the recording medium transfer device is set in the image forming apparatus, and the setting state of the recording medium transfer device is detected at low cost without using a special sensor. It is something that can be done.

FIG. 3 is a diagram showing a set detection flow of the recording medium transfer device 30 according to the present invention. After the home position of the recording medium transfer device 30 (the contact state is the home position in the flowchart) is determined, the density detection device 40 is operated with the set flag of the recording medium transfer device 30 set to S = 0. The output value of the density detection device 40 is confirmed. If the output value is 5 ( V ), the set abnormality of the recording medium transfer device 30 is detected. If the output value is 0 ( V ), the separation of the recording medium transfer device 30 is detected. Operation starts. Thereafter, the output value of the density detection device 40 is monitored, and if the output value from the density detection device 40 reaches 5 ( V ) when the separation operation of the recording medium transfer device 30 is completed, the normal operation is completed. However, when the output value is 0 ( V ), a set abnormality is detected.

  In addition, a plurality of toner density detection devices 40 can be used, and the configuration of the flowchart of FIG. Thereby, even if one of the toner concentration detection devices 40 breaks down, another toner concentration detection device 40 can be substituted.

  Further, the contact / separation operation of the recording medium transfer device 30 is performed a plurality of times, and at the same time, the detection by the toner concentration detection device 40 is also performed for the same number of times, so It is possible to prevent erroneous detection due to 40 malfunctions. As an example of the malfunction, for example, when the setting property of the recording medium transfer device 30 is insufficient, the operation from the home position state (contact state) to the separated state is performed, but the operation from the separated state to the contact state is performed. The case where it cannot do is mentioned.

FIG. 4 is a diagram showing a set detection flow of the recording medium transfer device 30 in the present invention, and more specifically, a diagram showing an example related to the fourth invention of the present application. The flow flow is the same as the flow shown in FIG. 3, but since the concentration detection device 40 is installed in the flow, three output values V1, V2, and V3 are detected, and the set flag is also the same. S1, S2, and S3. After the home position is detected, the output value of the density detection device 40 is detected. If the output value of each density detection device 4 is 0 ( V ), it is a normal value, and if it is 5 ( V ), a set error occurs. Further, when one or two density detection devices 40 are 5 ( V ), the density detection device 40 is abnormal, and hence the density detection device is abnormal. Similarly, even when the recording medium transfer device 30 is separated, a normal value is obtained if the output value from each density detection device 40 is 5 ( V ), and a set abnormality occurs if the output value is 0 ( V ). Further, when one or two concentration detection devices 40 are 0 ( V ), the concentration detection device 40 is abnormal, and hence the concentration detection device is abnormal.

  Therefore, as shown in FIG. 4, by using a plurality of toner density detection devices, judgments such as “normal operation”, “recording medium transfer device set failure”, “over toner density detection device output”, and the like can be made. Judgment can be made based on the difference in the output value of the toner density detection device due to the contact / separation operation of the medium transfer device. This makes it possible to detect the set of the recording medium transfer device and to detect the abnormality of the toner density detection device. it can.

1 is an example of an image forming apparatus to which the present invention is applied. It is an example which showed the change of the output value from the toner density | concentration detection apparatus 40 in this invention. FIG. 6 is a diagram illustrating a set detection flow of the recording medium transfer device 30 according to the present invention. FIG. 6 is a diagram illustrating a set detection flow of the recording medium transfer device 30 according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st image carrier 2 Cleaning device 3 Charging device,
5 Developing device 10 Second image carrier 11, 12 Roller 20 First transfer means 25 Cleaning device,
28 Registration Roller 30 Recording Medium Transfer Device 40 Toner Concentration Detection Device 50 Shutter 51 Cleaning Member 60 Spring

Claims (8)

An image carrier;
A recording medium transfer device for transferring a toner image on the image carrier to a recording medium;
A toner density detection device provided at a position facing the image carrier and detecting a toner image on the image carrier;
A shutter device for protecting the detection surface of the toner concentration detection device;
In an image forming apparatus comprising:
The recording medium transfer device is configured to be able to contact and separate from the image carrier,
The shutter device includes a window, and a shutter provided movably between the image carrier and the toner density detection device,
In a state where the recording medium transfer device is in contact with the image carrier, a detection surface of the toner density detection device is covered with the shutter,
When the recording medium transfer device is separated from the image carrier, the shutter moves so that the toner density detection device can detect the toner image on the image carrier through the window. And
When the recording medium transfer device moves in a direction in contact with the image carrier and in a direction away from the image carrier, the toner density detection device performs an operation of detecting a toner image on the image carrier, thereby An image forming apparatus for detecting a set state of a recording medium transfer device. The image forming apparatus according to claim 1.
The shutter device has biasing means for biasing the shutter,
The image forming apparatus, wherein the shutter moves when a part of the recording medium transfer device pushes the shutter against the urging force of the urging means. The image forming apparatus according to claim 2.
The image forming apparatus, wherein the recording medium transfer device is configured to be swingable about a fulcrum. The image forming apparatus according to claim 3.
An image forming apparatus, wherein a part of the recording medium transfer device is located on a side opposite to the fulcrum with respect to a position where the image carrier and the recording medium transfer device abut. The image forming apparatus according to claim 1,
The image forming apparatus includes a plurality of toner density detecting devices. The image forming apparatus according to claim 5.
An image forming apparatus characterized in that, when the results of set detection by the plurality of toner concentration detection devices do not match during the contact / separation operation of the recording medium transfer device, the toner concentration detection device is determined to be abnormal. . The image forming apparatus according to claim 1,
The image carrier is an intermediate transfer belt that is supported by a plurality of rollers and configured to be movable in a predetermined direction,
The recording medium transfer device is provided at a position facing one of the plurality of rollers across the intermediate transfer belt,
The image forming apparatus further includes:
A plurality of photoreceptors;
An image forming apparatus comprising: a first transfer unit that sequentially transfers toner images on the plurality of photosensitive members to the intermediate transfer belt . The image forming apparatus according to claim 1,
The image forming apparatus , wherein the toner density detecting device detects a toner density adjusting pattern .

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