JPH10161441A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a void in an image and to obtain an image of high quality, without being affected by environmental conditions, the kind of recording paper, etc., by executing control for making a certain speed difference between a fixed linear velocity at which an image carrier is rotated and the carrying speed of a recording medium. SOLUTION: A recording medium carrying speed control means 4 executes the control, so as to make the certain speed difference between the linear velocity V0 of an intermediate transfer belt 1b traveling in the direction of an arrow B by a driving roller 9 which is rotationally driven by a drive source and the carrying speed V1 of the recording medium P by the press-contact of a transfer roller 2 with the belt 1b. The recording medium carrying speed control means 4 controls the rotational speed of the servomotor 3a of a transfer roller driving means 3, so that a speed difference is made when the carrying speed V1 of the recording medium P detected by a speed detecting means 5 is compared with the linear velocity V0 of the belt 1b traveling in the direction of the arrow B. Thus, the radius of the transfer roller 2 is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an image forming apparatus such as a copying machine, a printer, a facsimile machine or a multifunction machine using an electrophotographic system, and more particularly, to recording a toner image formed on an image carrier. The present invention relates to an image forming apparatus that transfers an image to a medium to form an image.

[0002]

2. Description of the Related Art A conventional electrophotographic image forming apparatus, for example, a contact transfer type electrophotographic copying machine using an intermediate transfer member, transfers a toner image formed on a first image carrier onto an intermediate transfer member. Is provided for the primary transfer. When a color image of a plurality of colors is formed by the copying machine, the primary transfer process is repeated a plurality of times to sequentially transfer the toner images of a plurality of colors onto the intermediate transfer body in a superimposed manner. The multi-color toner superimposed image formed on the intermediate transfer body is secondarily transferred onto a recording sheet, and the multi-color image is transferred. As described above, in the case where the transfer is performed twice in total of the primary and the secondary in one image forming operation, and the single color or the composite color image is superimposed on the recording paper, FIG. b)
, A hollow image such as an insect-eating print as shown in FIG. A hollow image such as an insect print has a strong pressing force at the time of transfer, and the linear speed of the rotating intermediate transfer body and the conveying speed of the recording paper are constant, so that there is no shearing force to the toner and the image is separated. It is considered that this is likely to occur when the moldability deteriorates.

The transfer roller used to transfer the image on the intermediate transfer member to the recording paper in the image forming apparatus uses a rubber roller, and the use of the transfer roller causes a temporal decrease in the pressing force. There is a problem that the linear velocity is liable to fluctuate due to slip at the nip portion or the like because the recording paper is easily used and the types of recording paper used are large, and the friction coefficient (μ) and the releasability are different from each other. In addition, when the temperature in the apparatus rises in the case of continuous copying or the like, the roller diameter of the transfer roller changes due to thermal expansion, and the linear velocity of the transfer roller also fluctuates in this case. Particularly, in the case of double-sided copying, fluctuations in the linear velocity are significantly different from those in the case of backside copying and the case of frontside copying, so that many hollow images such as insect-eating prints have been generated. That is, the sliding resistance at the time of conveyance by the roller differs depending on whether or not the toner image is formed on one side, and thus the linear velocity fluctuates. Therefore, when the linear velocity fluctuates during the rotation of the transfer roller,
In the case where the transfer is performed twice or the like, since a single color or a composite color image is superimposed on the recording paper, more hollow images such as insect bite prints are generated, and a high quality formed image cannot be obtained. The problem described above had occurred.

[0004]

In the above-described conventional image forming apparatus, when the linear velocity during rotation of the transfer roller fluctuates, or when a single color or composite color image formed through two transfer steps is formed, When superimposed on recording paper, there is a problem that more hollow images such as insect-eating prints are generated and a high-quality formed image cannot be obtained. Therefore, an object of the present invention is to solve such a problem. That is, an object of the present invention is to provide an image forming apparatus capable of forming a high-quality image by preventing the occurrence of a hollow image such as an insect-eating print.

[0005]

According to an aspect of the present invention, there is provided an image forming apparatus for forming an image by transferring a toner image formed on an image carrier to a recording medium. An image carrier that carries the toner image and rotates at a predetermined linear velocity; and a toner image formed on the image carrier by being contact-charged from the back surface of the recording medium disposed opposite to the image carrier. A transfer roller for transferring to a recording medium, a transfer roller rotation speed adjusting means for adjusting a rotation speed of the transfer roller for pressing and conveying the recording medium to the image carrier, and a line when the image carrier rotates. It is characterized by comprising a recording medium conveyance speed control means for controlling a speed difference between the speed and the conveyance speed of the recording medium, and a speed detection means for detecting the conveyance speed of the recording medium. According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the transfer roller rotation speed adjustment means is a transfer roller drive means for driving the transfer roller to rotate, and the recording medium transport speed control means is a recording medium conveyance speed control means. The rotational speed of the transfer roller is controlled by controlling the transfer roller driving means, so that the difference between the linear velocity when the image carrier rotates and the linear velocity of the recording medium is made constant. Features. According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the transfer roller rotation speed adjusting means is a transfer roller pressing force adjusting means, and the recording medium conveyance speed controlling means is a transfer roller pressing force adjusting means. By controlling the means, the transfer roller controls the pressing force of pressing the recording medium against the image carrier, so that the speed difference between the linear velocity at which the image carrier rotates and the linear velocity of the recording medium is kept constant. It is characterized in that it is made to. According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, the transfer roller rotation speed adjustment means, etc.,
A transfer roller temperature adjusting unit, wherein the recording medium transport speed controlling unit controls the temperature of the transfer roller by controlling the transfer roller temperature adjusting unit, so that a linear speed at which the image carrier rotates and a recording medium It is characterized in that the speed difference from the linear speed is made constant. The invention of claim 5 is
The image forming apparatus according to claim 1, 2, 3, or 4,
The recording medium conveyance speed control means controls the linear velocity at which the recording medium is conveyed so that the difference between the linear velocity at which the image carrier rotates and the linear velocity is 0.3% to 2.0% slower or faster. It is characterized by doing. The invention according to claim 6 is based on claim 1,
6. The image forming apparatus according to 2, 3, 4 or 5, wherein the speed detecting means is disposed at a transfer outlet from which a recording medium is transferred while being pressed onto the image carrier by the transfer roller and sent out. . According to a seventh aspect of the present invention, in the image forming apparatus according to the first, second, third, fourth, fifth, or sixth aspect, the detecting units of the speed detecting unit are arranged at a plurality of locations.

[0006]

According to the first aspect of the present invention, in the image forming apparatus having the above-described structure, the recording medium conveying speed control means controls
The linear velocity (V0) when the image carrier (intermediate transfer body or photosensitive drum) rotates, and the rotation by the transfer roller rotation speed adjustment means (transfer roller drive means etc.) detected by the speed detection means Control is performed such that a constant speed difference (D) is generated between the transfer speed of the recording medium conveyed by the driven transfer roller and the conveyance speed (V1) of the recording medium without being affected by environmental conditions, the type of recording paper, and the like. The linear velocity of the image carrier (V0)
A constant speed difference between the print speed and the transport speed (V1) of the recording medium is prevented, and the occurrence of a hollow image such as an insect-eating print is prevented without being affected by environmental conditions and the type of recording paper. Thus, it is possible to provide an image forming apparatus in which a high quality image is formed. According to the second aspect, the rotation speed of the transfer roller by the transfer roller drive unit is adjusted by the recording medium conveyance speed control unit, and the predetermined linear speed (V0) at which the image carrier rotates is detected by the speed detection unit. A constant speed difference (D) between the conveying speed (V1) of the recording medium conveyed by the transfer roller rotated by the transfer roller driving means.
Is controlled so as to prevent the occurrence of a hollow image such as a bug-engraving print, without being affected by environmental conditions, types of recording paper, etc., by merely adjusting the rotation speed of the transfer roller. An image forming apparatus capable of forming a quality image can be provided. According to a third aspect of the present invention, a predetermined linear velocity at which the image carrier rotates by adjusting the pressing force of the transfer roller by the transfer roller pressing force adjusting means (transfer roller rotation speed adjustment means) by the recording medium conveying speed control means. (V
0) and a constant speed difference (D) between the conveyance speed (V1) of the recording medium conveyed by the transfer roller rotated by the transfer roller driving means detected by the speed detection means. By simply adjusting the pressing force of the transfer roller, it is possible to prevent the occurrence of hollow images such as insect-eating prints without being affected by environmental conditions, the type of recording paper, etc. An image forming apparatus in which formation is performed can be provided.

According to a fourth aspect of the present invention, the recording medium conveyance speed control means adjusts the temperature of the transfer roller by the transfer roller temperature adjustment means (transfer roller rotation speed adjustment means, etc.), and the predetermined line on which the image carrier rotates. The speed (V0) and the conveying speed (V1) of the recording medium conveyed by the transfer roller that is rotated and driven by the transfer roller driving unit detected by the speed detecting unit
The speed is controlled so that a constant speed difference (D) is generated between them. Therefore, only by adjusting the temperature of the transfer roller, it is not affected by the environmental conditions, the type of recording paper, and the like, and can be used as an insect-like print. It is possible to provide an image forming apparatus capable of forming a high-quality image while preventing the occurrence of a hollow image. According to a fifth aspect of the present invention, the recording medium is conveyed by a transfer roller rotated by a transfer roller driving means detected by a speed detecting means and a predetermined linear velocity (V0) at which the image carrier rotates by a recording medium conveying speed control means. A constant speed difference (D) is provided between the conveyance speeds (V1) of the recording medium, and this speed difference is determined by the linear speed (V).
Since 1) is controlled so as to be slower or faster by 0.3% to 2.0% with respect to the linear velocity (V0), the insect-eating prints are not affected by environmental conditions, types of recording paper, and the like. Thus, it is possible to provide an image forming apparatus capable of forming a high-quality image by reliably preventing the occurrence of a hollow image.
According to a sixth aspect of the present invention, the speed of the recording medium conveyance (V
1) is detected, and a predetermined linear velocity (V
0), the control is performed such that a constant speed difference (D) is generated without being affected by the environmental conditions, the type of the recording paper, and the like. Provided is an image forming apparatus that can detect and reliably prevent the occurrence of a hollow image such as an insect print, without being affected by environmental conditions, the type of recording paper, and the like, and form a high-quality image. You can do it. According to a seventh aspect of the present invention, the conveying speed (V1) of the recording medium is detected by speed detecting means arranged at a plurality of locations at the transfer outlet where the recording paper is less turbulent, and a predetermined linear speed (V0) at which the image carrier rotates. During this time, the control is performed such that a constant speed difference (D) is generated without being affected by the environmental conditions, the type of the recording paper, and the like. And the back side can be accurately detected, and the occurrence of a hollow image such as an insect-eating print is more reliably prevented without being affected by environmental conditions, the type of recording paper, etc.
An image forming apparatus capable of forming a high-quality image can be provided.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing a main part of an example of the apparatus of the present invention. In this image forming apparatus, a photosensitive drum 1a as an image carrier 1 held rotatably in a direction indicated by an arrow A in the drawing is shown. Around the intermediate transfer belt (intermediate transfer member) 1b as another image carrier 1 rotating in the direction of arrow B shown in the figure, and a charger (not shown) that uniformly charges the photosensitive drum 1a by corona discharge. A laser light emitting unit (not shown) composed of a laser diode for performing raster exposure based on a black signal and the like; A developing device (not shown) in which black toner or the like is adsorbed to form a toner image of black or the like similar to the latent image, and a black toner image formed on the photosensitive drum 1a by corona discharge. Intermediate transfer body 1b which is rotationally driven in contact with the body drum 1a
And a photoconductor cleaning unit (not shown) for scraping and removing a small amount of untransferred residual toner present on the photoconductor drum 1a in preparation for reuse of the photoconductor drum 1a. Are located.

The intermediate transfer belt as the intermediate transfer body 1b is stretched endlessly around a driving roller 9, an opposing roller 10, a roller 11, a roller 12, and the like, and is driven to rotate by the driving roller 9 in the direction of arrow B shown in the figure. . Transfer roller 2
Is disposed so as to face the outer side surface of the intermediate transfer member 1b, and performs contact charging from the back surface of the recording paper as the recording medium (P), so that the intermediate transfer member 1b as the image carrier 1
The toner image formed on the recording medium is secondarily transferred to recording paper of a recording medium (P). The transfer roller driving means (transfer roller rotation speed adjusting means) 3 is a transfer roller 2
And a servo motor 3a for rotating the motor
Intermediate gear train 3b for transmitting the rotational driving force of
Etc. The transfer roller 2 is for transferring the toner image formed on the intermediate transfer belt 1b to the recording medium (P). The recording medium is fed and conveyed from a recording medium feeding unit 14, and sent to a transfer position by a pair of registration rollers 15 in synchronization with the toner image formed on the intermediate transfer body 1b.

The recording medium conveying speed control means 4 controls a predetermined linear velocity (V0) of the intermediate transfer belt 1b traveling in a direction indicated by an arrow B by a driving roller 9 which is rotated by a driving source (not shown); Is the intermediate transfer belt 1
Control is performed such that a constant speed difference (D) is generated between the recording medium (P) and the conveyance speed (V1) of the recording medium (P) conveyed in the direction of arrow C by pressing against b. The recording medium conveyance speed control unit 4 includes a speed detection unit 5 disposed at a position shown in the figure.
Speed (V1) of the recording medium (P) detected by the
Is compared with the linear speed (V0) of the intermediate transfer belt 1b running in the direction of arrow B shown in the figure, and the rotation speed of the servo motor 3a of the transfer roller driving means 3 is controlled so that the above-mentioned speed difference (D) is generated. I do. The speed detecting means 5 has a detecting unit 5a composed of, for example, a reflection type photo sensor.
a is directed toward a predetermined position (detected portion). That is, when the recording medium (P) is sent out while being transferred while being pressed between the transfer roller 2 and the image carrier 1, the detection position of the detection unit 5 a is minimized. Position, that is, a plurality of locations on the near side and the far side of the transfer exit guide plate 13 of the transfer exit of the secondary transfer,
The detection unit 5a detects the transport speeds (V1) at a plurality of positions on the near side and the back side of the recording medium (P), and outputs the detected data to the servo motor 3a which is performed by the recording medium transport speed control unit 4.
Is reflected in the control of the rotation speed.

The linear velocity (V1) during conveyance of the recording medium (P), which is controlled by controlling the rotation speed of the transfer roller 2 by the recording medium conveyance speed control means 4, and the linear velocity at which the intermediate transfer belt 1b rotates. The purpose of the speed difference (D) from (V0) is to set the linear velocity (V0) at room temperature 23 ° C. and humidity 65% in the case of single-sided full-color copying when the recording medium (P) is the reference paper. ), The linear velocity (V1) is 0.
It is controlled to be 3% to 2.0% slower.
The same effect can be obtained even if the control is made to be 3% to 2.0% earlier. Accordingly, the linear speed (V1) at which the recording medium (P) is conveyed varies depending on the type of recording paper (P), the difference between single-sided or double-sided copy, environmental conditions, and the like. The intermediate transfer belt 1
0.3 to 2.0% of the linear velocity (b0) at which b rotates.
The rotation speed of the servo motor 3a is adjusted so that the predetermined speed difference (D) within the range of% slow or fast is maintained, and the rotation speed of the transfer roller 2 for conveying the recording medium (P) is also adjusted. It is supposed to be.

FIG. 2 is a diagram showing the rank of the image quality of a formed image in which a hollow image such as an insect print is generated with respect to the linear velocity (V1) at which the recording medium (P) is conveyed. By obtaining and clarifying it in advance through experiments and the like, it is possible to manually or automatically determine how slow or fast the recording paper conveyance linear velocity (V1) can be set to maintain appropriate image quality. The determination can be easily made even when performing.

FIG. 3 shows an image forming apparatus according to another embodiment of the present invention, in which a photosensitive drum 1a as an image carrier 1 held rotatably in the direction of arrow A is arranged in the direction of arrow B. An intermediate transfer belt (intermediate transfer body) 1b as an image carrier, a charger (not shown) for uniformly charging the photosensitive drum 1a by corona discharge, and a laser for performing raster exposure based on a black signal or the like A laser emitting unit (not shown) composed of a diode; and a developing unit (not shown) for forming a toner image of black or the like similar to the latent image by adsorbing black toner or the like only on the exposed portion of the photosensitive drum 1a where there is no charge. Drum 1a by corona discharge
The black toner image and the like formed on the photosensitive drum 1a
A corona discharger 8 for primary transfer to the surface of the intermediate transfer belt 1b which is rotationally driven in contact with the photosensitive drum 1a
A small amount of untransferred residual toner present on the photosensitive drum 1
A photoreceptor cleaning unit (not shown) that scrapes and removes a in preparation for reuse of a is disposed in the same manner as the above-described embodiment.
The description is omitted below.

The recording medium conveying speed control means 4 of this embodiment.
0 is a value between the predetermined linear velocity (V0) of the intermediate transfer belt 1b rotated in the direction of arrow B shown in the figure by the drive roller 9 rotated by a drive source (not shown) and the transfer roller 2 and the intermediate transfer belt 1b. This is a means for controlling a constant speed difference (D) between the recording medium (P) conveyed in the direction of arrow C and the conveyance speed (V1). The recording medium transport speed control means 40 controls the transport speed of the recording medium (P) (V
1) is detected by the speed detecting means 5, and this is compared with the linear velocity (V0) of the intermediate transfer belt 1b. Based on the comparison result, the transfer roller 2 is adjusted by the transfer roller pressing force adjusting means (transfer roller rotation speed or the like). An adjusting means 6 controls the pressing force for urging in the direction of arrow D shown in the figure. The conveyance speed (V1) of the recording medium is controlled by adjusting the pressing force. That is, the radius (d) of the transfer roller 2 that conveys the recording medium (P) is adjusted by adjusting the pressing force (kgf) for urging the transfer roller pressing force adjusting means 6 in the direction of arrow D.

The speed detecting means 5 has a detecting section 5a composed of, for example, a reflection type photo sensor, and is arranged with the detecting section 5a facing a predetermined position (detected section). That is, when the recording medium (P) is sent out while being transferred while being pressed between the transfer roller 2 and the image carrier 1, the detection unit 5 a is disposed at the position where the recording medium (P) is least exposed. That is, the transfer speed of the secondary transfer transfer outlet is selected at a plurality of positions on the front side and the back side of the transfer outlet guide plate 13, and the detection unit 5 a selects the transport speeds (a plurality of positions on the front side and the back side of the recording medium (P)). V1), and based on the detected data, the recording medium conveyance speed control unit 40 moves in the direction of arrow D of each transfer roller pressing force adjusting unit 6 (a plurality of transfer roller pressing force adjusting units 6 are arranged corresponding to the detecting unit 5a). To control the pressing force. The linear velocity (V1) during conveyance of the recording medium (P), which is controlled by controlling the rotation speed of the transfer roller 2 by the recording medium conveyance speed control means 4, and the linear velocity (V0) at which the intermediate transfer belt 1b rotates. The purpose of the speed difference (D) is that, in the case of single-sided full-color copying where the recording medium (P) is the reference paper, the linear velocity (V0) is lower than the linear velocity (V0) under the conditions of room temperature 23 ° C. and 65% humidity. Although the linear velocity (V1) is controlled to be slower by 0.3% to 2.0%, a similar effect can be obtained by controlling the linear velocity (V1) to be faster by 0.3% to 2.0%. Accordingly, the linear velocity (V1) at which the recording medium (P) is conveyed varies depending on the type of recording paper on the recording medium (P), single-sided or double-sided copying, environmental conditions, and the like. Each transfer roller maintains a predetermined speed difference (D) within a range 0.3% to 2.0% slower or faster than the linear speed (V0) at which the intermediate transfer belt 1b rotates. The pressing force (kgf) of the pressing force adjusting means 6 for urging in the direction of arrow D is adjusted, and the radius (d) of the transfer roller 2 for conveying the recording medium (P) is also adjusted.

FIG. 4 is a diagram showing the relationship between the change in the pressing force by the transfer roller pressing force adjusting means 6 and the change in the radius of the transfer roller. The pressing force D1 in the direction of arrow D by the transfer roller pressing force adjusting means 6 is shown. (Kgf)
When the transfer roller 2 is pressed by gf), the radius (d1) of the transfer roller 2 outside the end of the nip becomes longer (d2) due to the deformation of the transfer roller, and the recording medium (P) conveyed by the transfer roller 2 is moved. The transport speed (V11) also becomes a faster transport speed (V12).

FIG. 5 is a diagram showing the relationship between the change in the pressing force applied to the transfer roller and the conveyance speed of the recording medium. According to this figure, the transfer roller pressing force adjusting means 6 presses the transfer roller in the direction of arrow D. Recording medium (P) with increasing pressure D (kgf)
It is clear that the transport speed (V1) of the recording medium (P) is also increased by adjusting the pressing force D1 (kgf) by the transfer roller pressing force adjusting means 6.
1) can be adjusted. However, the pressing force D (k
If gf) is too high, the elongation of the transport speed (V1) of the recording paper on the recording medium (P) decreases. This is because the linear velocity (V0) at which the intermediate transfer belt 1b rotates and the recording medium (P) increase.
This is because the recording paper conveyance speed (V1) of the recording paper is sizzled. Therefore, by the recording medium conveyance speed control means 40,
The linear velocity (V1) at which the recording medium (P) is transported (mm /
s) varies depending on the type of recording paper on the recording medium (P), one-sided or two-sided copy, environmental conditions, and the like. However, the linear velocity (V1) (mm
/ S), a predetermined speed difference (D) within a range of 0.3% to 2.0% slower or faster than the linear speed (V0) at which the intermediate transfer belt 1b rotates is maintained. The pressing force D (kg) of the transfer roller pressing force adjusting means 6 is
By adjusting f), the radius (d) of the transfer roller 2 that conveys the recording medium (P) is also adjusted.

FIG. 6 is a schematic view of a main part of an image forming apparatus according to another embodiment of the present invention. This image forming apparatus includes a transfer roller temperature adjusting means (transfer roller rotation speed adjusting means) 7.
(The heater 7a and the thermistor 7b) and the configuration of the recording medium conveyance speed control means 400 are different from those of the above-described embodiments, and the description is not repeated. The recording medium conveyance speed control means 400 includes a linear velocity (V0) of the intermediate transfer belt 1b driven by a drive roller 9 rotated by a drive source (not shown) in the direction of arrow B, the transfer roller 2 and the intermediate transfer belt 1b. Is controlled so that there is a constant speed difference (D) between the recording medium (P) conveyed in the direction of arrow C and the conveyance speed (V1).
The recording medium conveyance speed control unit 400 compares the conveyance speed (V1) of the recording medium (P) detected by the speed detection unit 5 with the linear speed (V0) of the intermediate transfer belt 1b, and based on the comparison result, the transfer roller By controlling the temperature adjusting means 7, the temperature of the transfer roller 2 is controlled.
The transfer roller temperature adjusting means 7 is disposed below the transfer roller 2 and selectively heats the transfer roller.
It comprises a thermistor 7b for directly detecting the temperature by contacting the transfer roller 2 having a hydrating rubber on the base.

The speed detecting means 5 has a detecting section 5a composed of, for example, a reflection type photo sensor, and is arranged with the detecting section 5a facing a predetermined position (detected section). That is, the detection unit 5
When the recording medium (P) is sent out while being transferred while being pressed between the transfer roller 2 and the image carrier 1, the arrangement position of “a” is the position where the recording medium (P) is least exposed, that is, the secondary position. Transfer exit guide plate 13 for transfer exit of transfer
, A plurality of locations on the near side and the far side of the recording medium (P) are detected by the detection unit 5a, and the transport speeds (V1) at a plurality of locations on the near side and the far side of the recording medium (P) are detected, and recording is performed based on the detected data. The medium transport speed control unit 400 heats the transfer roller 2 by heating the heater 7a and the thermistor 7b of each of the plurality of transfer roller temperature adjusting units 7 corresponding to the detection unit 5a.
The temperature is controlled.

The linear velocity (V1) during conveyance of the recording medium (P), which is controlled by controlling the rotation speed of the transfer roller 2 by the recording medium conveyance speed control means 400, and the linear velocity at which the intermediate transfer belt 1b rotates. The speed difference (D) from (V0) is aimed at a single-sided full-color copy when the recording medium (P) is the reference paper, at room temperature of 23 ° C. and humidity of 6
Under the condition of 5%, the linear velocity (V1) is higher than the linear velocity (V0).
Is controlled to be slower by 0.3% to 2.0%, but the same effect can be obtained by controlling to be faster by 0.3% to 2.0%. Therefore, the linear velocity (V1) at which the recording medium (P) is conveyed depends on the type of recording paper of the recording medium (P),
Although it varies depending on single-sided or double-sided copying, environmental conditions, and the like, the recording medium conveyance speed control means 400 sets the linear speed (V0) of the intermediate transfer belt 1b to 0.
By adjusting the temperature of the transfer roller 2 by each transfer roller temperature adjusting means 7 so as to maintain a predetermined speed difference (D) within a range of 3% to 2.0% slower or faster, the recording medium (P), the diameter of the transfer roller 2 (2)
d) is also adjusted.

FIG. 7 is a diagram showing the relationship between the temperature of the transfer roller and the diameter of the transfer roller. According to this figure, the temperature of the transfer roller 2 is increased by the heating of the heater 7a of the transfer roller temperature adjusting means 7. It is clear that the diameter (2d) of the transfer roller 2 also becomes large, and by adjusting the heating temperature of the transfer roller temperature adjusting means 7 by the heater 7a, the conveying speed (V1) of the recording paper of the recording medium (P) is reduced. It is possible to adjust. Therefore, the recording medium transport speed control means 40
0, the linear velocity (V) at which the recording medium (P) is conveyed
1) (mm / s) is the type of recording paper of the recording medium (P),
A predetermined speed within 0.3% to 2.0% slower or faster than the linear speed (V0) at which the intermediate transfer belt 1b rotates, which varies depending on single-sided or double-sided copying, environmental conditions, and the like. In order to maintain the difference (D), the linear velocity (V1) (mm /
s) based on the detection result,
The diameter (2d) of the transfer roller 2 that conveys the recording medium (P) can be adjusted by adjusting the heating temperature of the heater 7a.

Next, FIG. 8 is a view showing an example in which the present invention is diverted to a transfer roller directly disposed to face a photoreceptor (in the case where an intermediate transfer member is not used). The transfer roller 2 is moved to the photosensitive drum 1a of the image carrier 1.
The toner image formed on the photosensitive drum 1a is directly transferred to the recording medium (P) by contact charging from the back surface of the recording medium (P). Applicable. According to this embodiment, the recording medium transport speed control means 4 (40, 400) of each of the above embodiments is
A predetermined linear velocity (V0) at which the photosensitive drum 1a as the image carrier 1 rotates in the direction of the arrow A, and a conveying speed (V) of the recording medium (P) conveyed by the transfer roller 2 in the direction of the arrow C
The control is performed such that a constant speed difference (D) is generated between 1 and 2 without being affected by environmental conditions, types of recording paper, and the like. The detection of the conveyance speed (V1) of the recording medium by the speed detection means 5 and the method of using the detection result by the recording medium conveyance speed control means 4 (40, 400) are the same as those in the above embodiments. The effects of this embodiment are the same as those of the above embodiments.

[0023]

As described above, according to the first aspect of the present invention, the predetermined linear velocity (V0) at which the image carrier (intermediate transfer member, photosensitive drum) rotates by the recording medium conveyance speed control means. Between the environmental conditions and the recording speed of the recording medium conveyed by the transfer roller rotated by the transfer roller rotation speed adjusting means (transfer roller driving means) detected by the speed detecting means. Control is performed so that a constant speed difference (D) is generated without being affected by the type of paper, etc., so that the predetermined linear speed (V0) at which the image carrier rotates and the transport speed (V1) of the recording medium are set. Just by making a constant speed difference, it is possible to prevent the occurrence of hollow images, such as insect-eating prints, without being affected by environmental conditions, types of recording paper, etc., and to form high-quality images. An image forming apparatus can be provided. According to the second aspect of the present invention, the rotation speed of the transfer roller by the transfer roller driving means (transfer roller rotation speed adjustment means) is adjusted by the recording medium conveyance speed control means, so that the image carrier rotates. Linear velocity (V
0) and the conveyance speed (V1) of the recording medium detected by the speed detection means is controlled so that a constant speed difference (D) is generated without being affected by environmental conditions, types of recording paper, and the like. As a result, simply adjusting the rotation speed of the transfer roller prevents the occurrence of hollow images such as insect-eating prints without being affected by environmental conditions, types of recording paper, etc. It is possible to provide an image forming apparatus in which is formed.

According to the third aspect of the present invention, the recording medium conveying speed control means adjusts the pressing force of the transfer roller by the transfer roller pressing force adjusting means (adjusting means for the rotational speed of the transfer roller, etc.), so that the image carrier is formed. Rotating predetermined linear velocity (V0)
And the transport speed (V) of the recording medium detected by the speed detecting means.
Since the control is performed such that a constant speed difference (D) is generated without being affected by the environmental conditions, the type of the recording paper, and the like between 1) and 1), the environmental conditions and the recording can be controlled only by adjusting the pressing force of the transfer roller. It has become possible to provide an image forming apparatus capable of forming a high-quality image by preventing the occurrence of a hollow image such as an insect-eating print without being affected by the type of paper or the like. According to the fourth aspect of the present invention, the predetermined temperature at which the image carrier rotates by adjusting the temperature of the transfer roller by the transfer roller temperature adjusting means (adjusting means such as the transfer roller rotation speed) by the recording medium conveying speed control means. A constant speed difference (D) between the linear speed (V0) and the transport speed (V1) of the recording medium detected by the speed detecting means without being affected by environmental conditions, types of recording paper, and the like.
Is controlled so as to prevent the occurrence of a hollow image such as a bug-eating print by simply adjusting the temperature of the transfer roller, without being affected by environmental conditions and types of recording paper. Thus, an image forming apparatus capable of forming a high-quality image can be provided.

According to the fifth aspect of the present invention, the recording medium conveyed by the transfer roller is detected by the recording medium conveying speed control means and the predetermined linear velocity (V0) at which the image carrier rotates, and detected by the speed detecting means. A constant speed difference (D) between the medium conveying speed (V1) and the environmental speed, the type of recording paper, etc.
And the linear velocity (V1) at which the recording medium (P) is conveyed is the linear velocity (V) at which the image carrier rotates.
Since the speed difference (D) from 0) is controlled to be slower or faster by 0.3% to 2.0%, the speed difference (D) is not affected by environmental conditions, recording paper type, etc. It has become possible to provide an image forming apparatus capable of forming a high-quality image by reliably preventing the occurrence of a missing image. According to the invention of claim 6, the conveyance speed (V1) of the recording medium is detected by the speed detection means disposed at the transfer outlet with less blur, and the predetermined speed at which the image carrier is rotated by the recording medium conveyance speed control means. Is controlled so as to generate a constant speed difference (D) between the linear velocity (V0) of the recording medium and the transport speed (V1) of the recording medium without being affected by environmental conditions, the type of recording paper, and the like. Can accurately detect the transport speed (V1) of the image, and reliably prevent the occurrence of a hollow image such as an insect-engraved print without being affected by environmental conditions, the type of recording paper, and the like, and realize a high-quality image. It has become possible to provide an image forming apparatus in which formation is performed.

According to the seventh aspect of the present invention, the transport speed (V1) of the recording medium is detected by a plurality of speed detecting means disposed at the transfer outlet with less rush, and the image carrier is controlled by the recording medium transport speed control means. Is controlled so that a constant speed difference (D) is generated between the predetermined linear speed (V0) at which the image is rotated and the conveyance speed (V1) of the recording medium without being affected by environmental conditions, the type of recording paper, and the like. As a result, the conveyance speed (V1) of the recording medium can accurately detect the front side and the back side at a plurality of locations, and is not affected by environmental conditions, the type of recording paper, and the like. It has become possible to provide an image forming apparatus capable of forming a high-quality image by more reliably preventing the occurrence of a hollow image.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating characteristics of a conveyance speed (V1) of a recording medium (P) and an image quality rank for explaining a state of a main part of the image forming apparatus according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating a main part of an image forming apparatus according to another embodiment of the present invention.

FIGS. 4A and 4B are diagrams illustrating the state of another main part of an image forming apparatus according to another embodiment of the present invention.

FIG. 5 is a diagram illustrating characteristics of a pressing force of a transfer roller and a conveyance speed of a recording medium for explaining a state of another main part of the image forming apparatus according to another embodiment of the present invention.

FIG. 6 is a diagram illustrating a main part of an image forming apparatus according to another embodiment of the present invention.

FIG. 7 is a diagram illustrating a characteristic of a transfer roller temperature and a transfer roller diameter for explaining a state of another main part of the image forming apparatus according to another embodiment of the present invention.

FIG. 8 is a diagram illustrating a main part of an image forming apparatus according to another embodiment of the present invention.

FIGS. 9A and 9B are diagrams illustrating defects of an image formed by a conventional image forming apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image carrier, 1a Photoreceptor drum, 1b Intermediate transfer body, 2 Transfer roller, 3 Transfer roller drive supply means, 3a
Servo motor, 3b intermediate gear train, 4 recording medium conveyance speed control means, 5 speed detection means, 5a detection unit, 6 transfer roller pressing force adjustment means, 7 transfer roller temperature adjustment means, 7a heater, 7b thermistor, 8 corona discharger , 9 drive roller, 10 opposed roller, 11 roller, 12 roller, 13 transfer exit guide plate, 14 paper feed unit, 15 registration roller pair, 40 recording medium conveyance speed control means, 400 recording medium conveyance speed control means

Claims (7)

[Claims] 1. An image forming apparatus for forming an image by transferring a toner image formed on an image carrier to a recording medium,
An image carrier that carries the toner image and rotates at a predetermined linear velocity; and a toner image formed on the image carrier by being contact-charged from the back surface of the recording medium disposed opposite to the image carrier. A transfer roller for transferring to a recording medium, a transfer roller rotation speed adjusting means for adjusting the rotation speed of the transfer roller for pressing and conveying the recording medium onto the image carrier, and a linear velocity when the image carrier rotates Recording medium transport speed control means for controlling a speed difference between the transport speed of the recording medium and
An image forming apparatus comprising: a speed detecting unit that detects a conveying speed of a recording medium. 2. The image forming apparatus according to claim 1, wherein
The transfer roller rotation speed adjustment means is a transfer roller driving means for driving the transfer roller to rotate, and the recording medium transport speed control means controls the transfer roller drive speed by controlling the transfer roller drive means. An image forming apparatus characterized in that the difference between the linear velocity when the image carrier rotates and the linear velocity of the recording medium is kept constant. 3. The image forming apparatus according to claim 1, wherein
The transfer roller rotation speed adjustment means is a transfer roller pressing force adjusting means, and the recording medium conveyance speed control means controls the transfer roller pressing force adjusting means so that the transfer roller records on the image carrier. An image forming apparatus comprising: controlling a pressing force for pressing a medium so as to make a speed difference between a linear speed at which the image carrier rotates and a linear speed of a recording medium constant. 4. The image forming apparatus according to claim 1, wherein
The transfer roller rotation speed adjustment means is a transfer roller temperature adjustment means, and the recording medium conveyance speed control means controls the transfer roller temperature adjustment means to control the transfer roller temperature, thereby controlling the image bearing. An image forming apparatus wherein a speed difference between a linear speed at which a body rotates and a linear speed of a recording medium is made constant. 5. The image forming apparatus according to claim 1, wherein the recording medium conveyance speed control means controls a linear speed at which the recording medium is conveyed and a linear speed at which the image carrier rotates. An image forming apparatus for controlling a speed difference between the image forming apparatus and the image forming apparatus to be slower or faster by 0.3% to 2.0%. 6. The image forming apparatus according to claim 1, wherein the transfer is performed by transferring the recording medium while the recording medium is pressed onto the image carrier by the transfer roller. An image forming apparatus, which is disposed at an outlet. 7. The image forming apparatus according to claim 1, wherein the detecting unit of the speed detecting unit comprises:
An image forming apparatus, wherein the image forming apparatus is arranged at a plurality of locations.