JP2001066836A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an excellent image formable by deciding the optimum transfer bias and the fixing temp. adjustment temp. in accordance with the kind of recording material, without introducing an exclusive recording material detecting device. SOLUTION: This image forming device detects a current to flow from an attraction roller 28 to the transport belt supporting roller 23a across the recording material P and a transport belt 22, with a current detecting circuit 32, at the time of transporting the recording material P by making the recording material P statically attracted between the transport belt 22 and the attraction roller 28 on which an attraction bias is applied from a high voltage circuit 31. Then, the device is made possible to obtain the excellent image, regardless of the quality of recording material P, by a control circuit 33, without employing a dedicated recording material detecting device by deciding the optimum transfer bias and the optimum fixing temp. for this recording material P, on judging the quality of the recording material P based on the current value detected through by the current detecting circuit 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a copying machine, a facsimile, and a printer for forming an image by an electrophotographic method.

[0002]

2. Description of the Related Art As an electrophotographic multi-color or full-color image forming apparatus, a plurality of photosensitive drums are arranged in a row in accordance with each color, and a toner image of each color formed on each photosensitive drum is transferred to a transfer material or an intermediate material. A so-called in-line type image forming apparatus has been proposed which forms a color image by sequentially superimposing the color image on a transfer body.

FIG. 5 shows an example of this type of color image forming apparatus.

This color image forming apparatus includes an image forming unit 1Y for forming a yellow (Y) color image and an image forming unit 1M for forming a magenta (M) color image.
And an image forming unit 1C for forming a cyan (C) color image, and an image forming unit 1Bk for forming a black (Bk) color image. These four image forming units are provided. 1Y, 1M, 1
C and 1Bk are arranged at a fixed interval from each other.

[0005] Image forming units 1Y, 1M, 1C, 1B
k includes photosensitive drums 2, 3, 4, and 5 as image carriers. Around each of the photosensitive drums 2, 3, 4, and 5, charging rollers 6, 7, 8, 9 and exposure devices 10, 1
1, 12, 13 and developing devices 14, 15, 16, 17
And transfer rollers 18, 19, 20, and 21, respectively.

[0006] Between the photosensitive drums 2, 3, 4, and 5 and the transfer rollers 18, 19, 20, and 21, the photosensitive drums 2, 3, 4, and 5 are electrostatically attracted to a recording material P such as paper. A transfer belt 22 is provided as an endless transfer material carrier that conveys the recording material P across the transfer section. The transport belt 22 includes a transport belt support roller 23a and a drive roller 23a.
b, and is rotated in the direction of the arrow by the rotation of the drive roller 23b.

Each of the photosensitive drums 2, 3, 4, and 5 is a negatively charged organic photosensitive member in the prior art and has a photoconductive layer on a drum substrate made of aluminum. It is rotationally driven at a predetermined process speed in the direction.

Next, an image forming operation by the above-described image forming apparatus will be described.

When an image forming operation start signal is issued, a recording material (paper) P of a predetermined size is sent out one by one from a cassette 25a by a pickup roller 24a.
Then, the recording material P is transported to the registration roller 26 by a paper feed roller (not shown) or the like. At this time, the registration roller 26 is stopped, and the leading end of the transfer material P is waiting just before the registration roller 26. The recording material P on the manual feed tray 27 is similarly sent out one sheet at a time by the pickup roller 24 b and conveyed to the registration roller 26.

On the other hand, each of the image forming units 1Y, 1M, 1C, 1
In Bk, when an image forming operation start signal is issued, each of the photosensitive drums 2 driven to rotate at a predetermined process speed,
The charging rollers 3, 4, 5 are uniformly charged to predetermined polarity (for example, negative polarity) by the charging rollers 6, 7, 8, 9, respectively. And exposure devices (laser scanning units) 10, 11, 12, 1
Reference numeral 3 denotes a laser output unit (not shown) that converts the input color-separated image signal into an optical signal, and converts the laser light, which is the converted optical signal, into each of the charged photosensitive drums 2, 3,. An electrostatic latent image is formed by scanning and exposing on 4 and 5, respectively.

First, a yellow toner is applied to the electrostatic latent image formed on the photosensitive drum 2 by a developing sleeve of a developing device 14 to which a developing bias having the same polarity as the charging polarity (negative polarity) of the photosensitive drum 2 is applied. To form a visible image as a toner image.

In accordance with the formation of the toner image, the transfer material (paper) P is attracted and conveyed onto the transport belt 22 by the rotation of the registration roller 26 and the attraction roller 28 to which the attraction bias is applied. The yellow toner image is transferred onto the recording material P at the transfer nip between the photosensitive drum 2 and the transfer roller 18 by the transfer roller 18 to which the polarity (positive polarity) opposite to that of the toner is applied.

The recording material P on which the yellow toner image has been transferred
Is transported to the image forming unit 1M by suction transport by the transport belt 22. Then, the image forming unit 1M
In this case, the magenta toner image formed on the photosensitive drum 3 in the same manner as described above is superimposed and transferred on the yellow toner image on the transfer material P.

Hereinafter, cyan and black toner images formed by the photosensitive drums 4 and 5 of the image forming units 1C and 1Bk are sequentially formed on the yellow and magenta toner images superimposedly transferred onto the transfer material P in the same manner. By superimposing, a full-color toner image is formed on the recording material P.

The recording material P on which the full-color toner image is formed is fixed to a fixing roller 29a of a fixing device 29 and a pressing roller 2a.
9b, the fixing roller 29a and the pressure roller 29
After the full-color toner image is heat-fixed to the surface of the recording material P by heating and pressing by b, the sheet is discharged outside, and a series of image forming operations is completed.

[0016]

In the above-described image forming apparatus, a transparent or translucent OH is used as the recording material P.
When a P film is used, the heat capacity is larger and thicker than that of a thin plain paper which is usually used, so that it is necessary to switch image forming conditions and the like to conditions different from those suitable for the plain paper. .

However, in order to provide an image forming apparatus that satisfies the optimum transfer bias conditions and the like even when an OHP film is used, it is necessary to introduce a means for detecting the material of the recording material P. Introducing a dedicated detector requires a new space in the apparatus, which increases the size of the apparatus and increases the cost.

In the above-described image forming apparatus, the transport belt 22 for sucking and transporting the recording material P is liable to be rubbed between the photosensitive drums 2, 3, 4, 5 and the recording material P.
Has a predetermined life. For this reason, if the transport belt 22 is used beyond its service life, the image quality will be degraded due to poor transfer or the like. Therefore, it is necessary to introduce a means for detecting the service life of the transport belt 22. Introducing a vessel requires a new space in the apparatus, which increases the size of the apparatus and increases the cost.

Therefore, according to the present invention, it is possible to form an image by controlling the optimum transfer bias and the fixing temperature in accordance with the type of the recording material without introducing a dedicated detector. It is an object of the present invention to provide an image forming apparatus capable of easily detecting the life of a printer.

[0020]

According to a first aspect of the present invention, there is provided a transfer unit for transferring a developer image formed on an image carrier to a recording material at a transfer unit. A transfer bias applying unit that applies a transfer bias to a transfer unit; an endless transport belt that transports the recording material to the transfer unit; and an electrostatic transfer device that applies the recording material on the transport belt upstream of the transfer unit. The image forming apparatus according to claim 1, further comprising: a suction unit configured to perform suction, a suction bias application unit configured to apply a suction bias to the suction unit, and a fixing unit configured to thermally fix the developer image transferred onto the recording material. When the recording material is conveyed between the suction unit and the conveyance belt, and the recording material is electrostatically adsorbed on the conveyance belt by the suction unit to which the adsorption bias is applied from the suction bias application unit, Record A current value detecting means for detecting a current value flowing to the suction means through the transfer means, and the transfer bias such that an optimum transfer bias is applied to the transfer means based on the current value detected by the current value detecting means. Controlling the application unit, and further, when it is determined that the current value detected by the current value detection unit is smaller than the first determination value, the fixing temperature controlled by the fixing unit is set higher than normal. And control means for controlling.

According to a second aspect of the present invention, there is provided a transfer unit for transferring a developer image formed on an image carrier to a recording material at a transfer unit, and a transfer bias application for applying a transfer bias to the transfer unit. Means, an endless conveyance belt for conveying the recording material to the transfer section, suction means for electrostatically adsorbing the recording material on the conveyance belt upstream of the transfer section, and suction to the suction means An image forming apparatus comprising: an attraction bias applying unit that applies a bias; and a fixing unit that thermally fixes the developer image transferred onto the recording material. When the recording material is electrostatically attracted onto the transport belt by the suction means to which the suction bias has been applied from the suction bias application means, the current flowing through the suction means via the recording material Current value detecting means for detecting the current value, controlling the transfer bias applying means based on the current value detected by the current value detecting means so that an optimal transfer bias is applied to the transfer means, When it is determined that the current value detected by the value detection unit is smaller than the first determination value, the control unit controls the fixing temperature controlled by the fixing unit to be higher than normal, and the next recording material is And control means for controlling the time interval for conveying to the fixing means to be longer than usual.

In a state in which the recording material is not conveyed on the conveyance belt, an attraction bias is applied to the attraction means from the attraction bias applying means, and a current value flowing through the attraction means at this time is determined by the current. If the current value detected by the current value detecting means is larger than a second determination value,
It is characterized in that it is determined that the transport belt has reached the end of its life.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments.

<First Embodiment> FIG. 1 is a schematic configuration diagram showing a main part of an image forming apparatus according to a first embodiment of the present invention. The same members as those of the above-described conventional image forming apparatus are denoted by the same reference numerals, and redundant description will be omitted. Also in the present embodiment, image formation is performed in the same manner as in the above-described conventional image forming apparatus, and a detailed description of the image forming operation is omitted in the present embodiment.

In this image forming apparatus, as shown in FIG.
Each transfer roller (the transfer roller 1 of the image forming unit 1Y in the figure)
8), a high-voltage control circuit 30 is connected to apply a predetermined transfer bias to the recording material P via the transport belt 22. In addition, a suction bias is applied to the suction roller 28 from the high voltage circuit 31, and the recording material P is electrostatically suctioned to the transport belt 22. The high-voltage circuit 31 includes a conveyance belt 2 for the recording material P.
The transfer belt 2 is moved from the suction roller 28 to
2, a current detection circuit 32 for detecting a current flowing into the conveyor belt support roller 23a is connected.

In this embodiment, the suction roller 2
8, the material of the recording material P is determined based on the current value information flowing into the transport belt support roller 23a via the recording material P and the transport belt 22, and the transfer bias applied to the transfer roller 18 is optimally controlled based on the determination result. I did it. Further, when it is determined from the current value information that the recording material P is an OHP film, the fixing temperature control temperature is controlled to be higher than in the case of ordinary paper.

Hereinafter, the control in this embodiment will be described with reference to FIG.
This will be described with reference to the flowchart shown in FIG.

As described in the conventional example shown in FIG. 5, the recording material P is picked up by the pickup roller 24a (or 24b).
Is started (step S1), and the registration rollers 26
Immediately before the recording material P is temporarily stopped (step S2).
Then, an electrostatic latent image of each color (yellow, magenta, cyan, black) corresponding to the image information is formed on each of the photosensitive drums 2, 3, 4, and 5, and these developing devices 14 , 15, 16 and 17 to apply toner and start development (step S3). Then, the recording material P is restarted by the registration roller 26 and fed between the conveyance belt 22 and the suction roller 28 (Step S).
4).

Then, from the high voltage circuit 31 to the suction roller 28
To apply a suction bias to the recording material P
The recording material P is conveyed to a transfer nip between the photosensitive drum 2 and the transfer roller 18 by electrostatic attraction. At this time, the conveyance belt support roller 23 is moved from the suction roller 28 via the recording material P.
The current flowing into a (hereinafter, referred to as an attraction current) is detected by the current detection circuit 32 (step S5). Control circuit 33
Can determine the material of the recording material P based on the attracting current value input from the current detection circuit 32.

The control circuit 33 compares the current (attraction current) input from the current detection circuit 32 with a predetermined value (step S6), and determines whether the input current (attraction current) is a predetermined value. If it is determined that the recording material P is larger than the recording medium P, it is determined that the recording material P is a normal sheet. To determine the optimal transfer bias, and apply the determined transfer bias (step S8).

In step S6, if the control circuit 33 determines that the input current (adsorption current) value is smaller than a predetermined value, it determines that the recording material P is an OHP film, and the fixing roller of the fixing device 29 The fixing temperature at 29a is controlled so as to be higher than usual corresponding to the OHP film (step S7). The ROM of the control circuit 33
(Not shown) stores information such as a predetermined value of the above-mentioned attracting current value, an optimum transfer bias value according to the inputted attracting current value, and a material of the recording material P according to the inputted attracting current value. Have been.

Then, the transfer bias value of each color determined in step S8 is applied from the high-voltage control circuit 30 to each transfer roller (the transfer roller 18 of the image forming unit 1Y in the figure), and as described in the conventional example, Are superimposed and transferred (step S9) to form a color image. The recording material P on which the color toner image is formed is conveyed between the fixing roller 29a and the pressure roller 29b of the fixing device 29 and heated by the fixing roller 29a and the pressure roller 29b, as in the conventional example shown in FIG. After the full-color toner image is thermally fixed on the surface of the recording material P by pressure, the sheet is discharged to the outside (steps S10 and S11).

In step S10, when the toner image formed on the recording material P is thermally fixed by the fixing device 29, if it is determined in step S6 that the recording material P is an OHP film, the process proceeds to step S7. On the basis of the fixing temperature, the fixing is performed at a higher temperature than in the case of the recording material P such as ordinary paper.

As described above, in the present embodiment, the conveying belt supporting roller 23a from the suction roller 28 via the recording material P
The material of the recording material P is detected based on the attracting current value flowing into the recording material P, and the optimum transfer bias can be determined based on the detected information.
If it is determined that the OHP film is an OHP film, the fixing can be performed at a high fixing temperature so that the optimum fixing condition can be obtained. Therefore, the recording can be performed with a simple configuration without providing a dedicated recording material detecting device or the like. Good images can be obtained regardless of the material of the material.

<Embodiment 2> The image forming apparatus of the present embodiment will be described using the image forming apparatus of Embodiment 1 shown in FIG. 1 and the conventional image forming apparatus shown in FIG. .

In the image forming apparatus of the present embodiment, similarly to the first embodiment, the recording material P based on the recording material P from the suction roller 28 and the current value information flowing into the transport belt support roller 23a via the transport belt 22 is used. The transfer bias value applied to the transfer roller 18 is optimally controlled based on the determination result. Furthermore, when it is determined from the current value information that the recording material P is an OHP film, the fixing temperature control temperature is set higher than that in the case of ordinary paper, and
If it is determined that the previous (previous) recording material P was an OHP film, the start of the development of the electrostatic latent image is delayed by a predetermined time, and the heating time of the heater (not shown) of the fixing device 29 is extended. The following control is performed.

Hereinafter, the control in this embodiment will be described with reference to FIG.
This will be described with reference to the flowchart shown in FIG.

As in the first embodiment, the conveyance of the recording material P is started by the pickup roller 24a (or 24b) (step S1), and the recording material P is temporarily stopped immediately before the registration roller 26 (step S2).

Here, the preceding (previous) recording material P is OH
The control circuit 33 determines whether the film is a P film (step S2a). This determination can be made based on a suction current value detected by the current detection circuit 32 when the previous recording material P was conveyed between the conveyance roller 22 and the suction roller 28.

In step S2a, the last recording material P is OH
In the case of a P film, a predetermined delay time is provided, and after this delay time elapses, each of the developing devices 14, 15, 1 is applied to the electrostatic latent image formed on each of the photosensitive drums 2, 3, 4, 5 respectively.
The development is started by attaching the toner according to steps 6 and 17 (step S3). This delay time can increase the temperature rise time by the heater (not shown) of the fixing device 29, so that the previous color toner image on the OHP film as the recording material P can be sufficiently heated and fixed. The ROM (not shown) of the control circuit 33 stores a predetermined value of the above-mentioned attracting current value, an optimal transfer bias value according to the inputted attracting current value, and a recording material P corresponding to the inputted attracting current value. The information such as the material is stored.

In step S2a, the current detection circuit 3
If the previous recording material P is not OHP film but ordinary paper based on the adsorption current value detected in step 2, development of the electrostatic latent image is started as usual in step S3. Step S3 and subsequent steps are the same as in the first embodiment, and a description thereof will be omitted in the present embodiment.

As described above, in the present embodiment, the conveying belt supporting roller 23a from the suction roller 28 via the recording material P
The material of the recording material P is detected based on the value of the attracting current flowing into the recording medium P, and the optimum transfer bias can be determined based on the detected information.
If it is determined that the OHP film is an OHP film, the fixing can be performed at a high fixing temperature so that the optimum fixing condition can be obtained. Therefore, the recording can be performed with a simple configuration without providing a dedicated recording material detecting device or the like. Good images can be obtained regardless of the material of the material.

The preceding (previous) recording material P is OHP
In the case of a film, the start of development of the electrostatic latent image is delayed by a predetermined time, so that the previous color toner image on the OHP film as the recording material P can be sufficiently heated and fixed.

<Embodiment 3> The image forming apparatus of the present embodiment will be described using the image forming apparatus of Embodiment 1 shown in FIG. 1 and the conventional image forming apparatus shown in FIG. .

In the image forming apparatus according to the present embodiment, when the recording material P is not conveyed on the conveyance belt 22, it is based on current value information flowing from the suction roller 28 to the conveyance belt support roller 23 a via the conveyance belt 22. To calculate the resistance value of the conveyor belt 22, and from the calculation result,
2 was determined.

Hereinafter, the control in this embodiment will be described with reference to FIG.
This will be described with reference to the flowchart shown in FIG.

First, in a state where the recording material P is not conveyed on the conveying belt 22, the high pressure circuit 31
The current flowing into the conveyor belt support roller 23a from the adsorption roller 28 via the conveyor belt 22 at this time is measured by the current detection circuit 32 (step S21).

The control circuit 33 compares the attracting current value input from the current detecting circuit 32 with a predetermined value set in advance (step S22), and determines that the inputted attracting current value is larger than the predetermined value. Determines that the life of the transport belt 22 has expired due to wear or the like (step S23). As described above, the control circuit 33 can detect the life of the transport belt 22 by calculating the resistance value of the transport belt 22 from the input attracting current value and comparing it with the resistance value at the time of the preset life. . The ROM of the control circuit 33
(Not shown), the resistance value of the conveyor belt 22 according to the above-mentioned input attracting current value,
2 stores information such as a resistance value at the time of life.

When it is determined that the transport belt 22 has reached the end of its life, a display unit (not shown) displays, for example, "the transport belt has reached its end of life", and warns the user.

If it is determined in step S22 that the input attracting current value is larger than the predetermined value, it is determined that the life of the conveyor belt 22 is still sufficient, and the same operation as in the conventional image forming apparatus described above is performed. A normal image forming operation (printing operation) is performed (step S24).

As described above, in the present embodiment, in a state where the recording material P is not conveyed onto the conveyance belt 22, the life of the conveyance belt 22 is determined based on a suction current value flowing from the suction roller 28 to the conveyance belt support roller 23a. It is possible to detect the life of the conveyor belt 22 with a simple configuration without providing a dedicated conveyor belt detection device or the like, and to prevent the deterioration of image quality due to the life of the conveyor belt 22 beforehand. Can be.

[0052]

As described above, according to the first aspect of the present invention, the optimum transfer bias can be determined based on the current value flowing to the suction means via the recording material. When it is determined that the current value detected by the means is smaller than the first determination value, the fixing can be performed with the fixing temperature adjusted by the fixing means higher than usual. A good image can be obtained with a simple configuration irrespective of the material of the recording material without providing any other means.

According to the second aspect of the present invention, the optimum transfer bias can be determined based on the current value flowing to the suction means via the recording material, and further, the current detected by the current value detection means can be determined. When it is determined that the value is smaller than the first determination value, the fixing is performed by setting the fixing temperature adjusted by the fixing unit higher than usual, and the time interval at which the next recording material is conveyed to the fixing unit is set. By making it longer than usual,
A good image can be obtained with a simple configuration regardless of the material of the recording material without providing a dedicated recording material detection device or the like.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating a main part of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing control according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing control according to Embodiment 2 of the present invention.

FIG. 4 is a flowchart showing control according to Embodiment 3 of the present invention.

FIG. 5 is a schematic configuration diagram showing an image forming apparatus in a conventional example.

[Explanation of symbols]

2, 3, 4, 5 Photosensitive drum (image carrier) 18, 19, 20, 21 Transfer roller (transfer unit) 22 Conveyor belt 23a Conveyor belt support roller 28 Suction roller (adsorber) 30 High voltage control circuit (transfer bias application) Means) 31 High voltage circuit (Suction bias applying means) 32 Current detection circuit (Current value detecting means) 33 Control circuit (Control means)

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H027 DA01 DA12 DA32 DE05 DE07 DE09 EA03 EA12 EC06 EC09 ED24 ED25 EF01 JC03 JC08 JC09 JC13 2H032 AA05 AA15 BA05 BA11 BA18 BA21 BA26 CA02 CA14 DA01 DA08 DA23 DA27 BA17 BA032H03 CA07 CA08 CA09 CA30

Claims (3)

[Claims] A transfer unit configured to transfer a developer image formed on an image carrier to a recording material at a transfer unit; a transfer bias applying unit configured to apply a transfer bias to the transfer unit; An endless conveyance belt for conveying to a transfer unit; an adsorption unit for electrostatically adsorbing the recording material on the conveyance belt upstream of the transfer unit; and an adsorption bias application unit for applying an adsorption bias to the adsorption unit. An image forming apparatus comprising: a fixing unit that thermally fixes the developer image transferred onto the recording material; wherein the recording material is conveyed between the suction unit and the conveyance belt; A current value detecting means for detecting a current value flowing through the attraction means via the recording material when the recording material is electrostatically attracted onto the transport belt by the attraction means to which the attraction bias is applied from the application means; And controlling the transfer bias applying unit based on the current value detected by the current value detecting unit so that an optimal transfer bias is applied to the transfer unit, and further detecting the current value by the current value detecting unit. Control means for controlling the fixing temperature by the fixing means to be higher than usual when it is determined that the current value is smaller than the first determination value. apparatus. 2. A transfer unit for transferring a developer image formed on an image carrier to a recording material at a transfer unit; a transfer bias applying unit for applying a transfer bias to the transfer unit; An endless conveyance belt for conveying to a transfer unit; an adsorption unit for electrostatically adsorbing the recording material on the conveyance belt upstream of the transfer unit; and an adsorption bias application unit for applying an adsorption bias to the adsorption unit. An image forming apparatus comprising: a fixing unit that thermally fixes the developer image transferred onto the recording material; wherein the recording material is conveyed between the suction unit and the conveyance belt; A current value detecting means for detecting a current value flowing through the attraction means via the recording material when the recording material is electrostatically attracted onto the transport belt by the attraction means to which the attraction bias is applied from the application means; And controlling the transfer bias applying unit based on the current value detected by the current value detecting unit so that an optimal transfer bias is applied to the transfer unit, and further detecting the current value by the current value detecting unit. If it is determined that the current value is smaller than the first determination value, control is performed so that the fixing temperature controlled by the fixing unit is higher than normal, and the next recording material is conveyed to the fixing unit. Control means for controlling the time interval to be longer than usual,
An image forming apparatus comprising: 3. In a state where the recording material is not conveyed on the conveyance belt, an attraction bias is applied to the attraction means from the attraction bias applying means, and a current value flowing through the attraction means at this time is set to the current value. Value control means, and when the control means determines that the current value detected by the current value detection means is greater than a second determination value, the control means determines that the transport belt has reached the end of its life. The image forming apparatus according to claim 1, wherein: