JP3403185B2 - Image forming device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an image forming apparatus, and more particularly, it transfers a toner image on an image carrier formed by an electrophotographic system or an electrostatic recording system onto a transfer material. The present invention relates to an image forming apparatus that obtains an image by applying and transferring an electric field. Such image forming apparatuses include black-and-white, mono-color or full-color electrophotographic copying machines, printers and various other recording devices.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus employing an electrophotographic process, a toner image formed on an image bearing member such as a photosensitive drum is generally transferred to a sheet-like transfer material such as paper via a transfer device. Is transcribed to.

A ring member 9 at both ends shown in FIG. 8 is used as a transfer device for carrying a transfer material and transferring the toner images on the same transfer material a number of times.
A frame 49 in which a and 9b are connected by a connecting portion 9c.
Further, there is known a transfer drum 9 having a structure in which a dielectric sheet 93 as a flexible transfer material supporting member shown in FIG. 9 is wound and the transfer material P is adsorbed and held on the dielectric sheet 93. There is.

When the transfer material gripping member, for example, the transfer material gripper 7 of FIG. 13 is not provided on the transfer drum 9, as shown in FIG. 10, a suction corona charger 39 and a dielectric sheet 93 which are suction means. An image forming apparatus is known in which a suction roller 40 as a transfer material urging unit is provided at a position facing the suction corona charger 39 with the suction roller interposed therebetween.

In the image forming apparatus having such a structure,
The suction roller 40 is brought into contact with the transfer drum 9 only during the suction operation, and the suction roller 40 is separated from the transfer drum 9 at least once before the transfer material P on which the toner image is transferred passes through the suction position. The unfixed toner image transferred to the transfer material P is prevented from being retransferred to the suction roller 40. However, even with this configuration, the fog toner in the non-image area attached to the photosensitive drum 3 is transferred to the transfer material non-adhesion area of the dielectric sheet 93, and the fog toner is attracted by the suction roller 40.
Or the toner scattered in the apparatus is adsorbed by the adsorbing roller 40, and the adhering roller 40 is gradually soiled with toner. Therefore, in order to prevent the dirt from adhering to the surface of the transfer material P again during the suction operation, a scraper 52 as a cleaning unit is provided, and the toner adhering to the surface of the suction roller 40 by the operation of rotating the suction roller 40. It is configured to scrape off.

FIG. 11 is a detailed view showing the operating state of the suction roller.

The scraper 52 is supported at one end of a swing plate 53 that supports the suction roller 40. The swing plate 53 is a bell crank, and is swingably supported by a support shaft 45. One end is locked to the other end of the rocking plate 53, and the suction roller 40 is biased toward the transfer drum 9 by a pressure spring 54 whose other end is locked to a stationary part.

FIG. 12 shows the state in which the suction roller 40 is separated from the transfer drum 9 as described above. At this time, the end of the scraper 52 is in contact with the suction roller 40.

[0009]

However, even with the above-mentioned conventional technique, the toner adhering to the suction roller 40 cannot be completely cleaned, and stains may be accumulated. This is due to the following reasons.

That is, in the conventional image forming apparatus, as shown in FIG.
As shown in 0, in order to shorten the image forming time, the first transfer operation from the time when the leading end of the transfer material P reaches the position where the transfer drum 9 and the photosensitive drum 3 face each other during the suction operation of the transfer material P. It is carried out. That is, a state occurs in which the suction operation and the transfer operation are simultaneously performed. At this time, it is necessary to completely match the peripheral speeds of the suction roller 40 and the transfer drum 9, otherwise, the transfer speed of the transfer material P during transfer is slightly affected, while the second and subsequent transfer operations are being performed. Is the suction roller 4
Since 0 is separated from the transfer drum 9, this effect does not occur, and as a result, the transfer speed of the first time and the transfer speed of the second time and thereafter are slightly deviated, and in particular, multicolor toner is transferred by plural times of transfer. In a color image forming apparatus, a color shift occurs, which causes deterioration of image quality.

In order to surely and easily realize the above conditions, the suction roller 40 does not have a drive source, and is structured so as to follow the transfer drum 9 by the frictional force with the transfer drum 9. The peripheral speeds of the rollers 40 are matched.

Therefore, the driving torque for rotating the suction roller 40 is naturally limited, and it has been difficult to increase the contact pressure of the scraper 52 above a certain level.
Further, in order to increase this, when the contact pressure for bringing the suction roller 40 into contact with the transfer drum 9 is increased, the suction roller 4
A shock is generated when 0 is attached or detached, or when the transfer drum 9 is contacted
However, there is a contradiction that it is desirable to lower the contact pressure of the suction roller 40 in order to improve the image quality, because the speed fluctuations of 1) cause the image quality to deteriorate.

For the above reasons, the contact pressure of the scraper 52 with respect to the suction roller 40 cannot be increased, and as a result, the suction roller 40 cannot be sufficiently cleaned, so that the untransferred transfer material P is contaminated. There was a problem that it occurred.

According to the present invention, the above-mentioned problems are solved by the cleaning means of the charging means for electrostatically attracting and holding the transfer material carrying member to the transfer material carrying member which comes into contact with and separates from the transfer material carrying member. An object is to provide a solved image forming apparatus.

[0015]

The first and second inventions of the present invention are intended to solve the problems. The cleaning means can be brought into contact with or separated from the transfer material urging means, and the suction operation can be performed. When the cleaning means is separated from the transfer material urging means, it does not prevent the transfer material urging means from being driven, and the cleaning means has a sufficient contact pressure during the non-suction operation. By bringing it into contact with the transfer material urging means, it is possible to obtain a sufficient cleaning effect without deteriorating the image quality.

A typical invention of the present invention is a transfer material carrier for supporting a transfer material, a charging means for electrostatically holding the transfer material on the transfer material carrier, and the transfer material carrier. Cleaning is performed by contacting the roller-shaped transfer material urging means facing the charging means with the transfer material urging means interposed therebetween and urging the transfer material toward the transfer material carrier, and the surface of the transfer material urging means. in the image forming apparatus having a cleaning unit, the cleaning unit
Is capable of coming into contact with and separating from the transfer material urging means,
The transfer material urging means can be brought into contact with and separated from the transfer material carrier.
And the transfer material urging means is separated from the transfer material carrier.
Drive from the drive source to the transfer material urging means.
The transfer material urging means comes into contact with the transfer material carrier.
In this case, the drive from the drive source causes the transfer material urging means to move.
The transfer material urging means is configured so as not to be transmitted to
When the transfer material carrier is contacted, the transfer material urging means
The step is rotated by friction with the transfer material carrier, and
The cleaning means is separated from the transfer material urging means, and
When the copying material urging means is separated from the transfer material carrier,
The transfer material urging means is rotated by the drive source.
The cleaning means comes into contact with the transfer material urging means.
And an image forming apparatus.

[0017]

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to the present invention will be described in detail below with reference to the drawings.

[First Embodiment] A first embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a schematic vertical sectional view of a color image forming apparatus, in which a photosensitive drum 3 as an image carrier is axially supported at its center and is rotationally driven in the arrow direction. A primary charger 4, an exposure unit 8, a developing device 1, and a secondary charger 55 are arranged in the rotational direction of the photosensitive drum 3 so as to face the outer peripheral surface of the photosensitive drum 3. The primary charger 4 is the photosensitive drum 3
Gives a uniform charge amount to. The exposure unit 8 forms the electrostatic latent image by applying the color-separated optical image E or a light beam corresponding thereto to the surface of the photosensitive drum 3 at a predetermined timing.
A laser beam exposure device or the like is used for the exposure means 8.

Further, the developing device 1 includes four developing devices 1M, 1C, each containing a magenta color developer (hereinafter referred to as toner), a cyan color toner, a yellow color toner, and a black color toner. It has 1Y and 1BK. The developing device 1 is of a movable type that moves in a tangential direction so as to face the surface of the photosensitive drum 3, and corresponds to the irradiation of a light image E of a selected color by the exposure means 8 or a light beam corresponding thereto. Selected developing device 1M, 1C, 1Y, 1B
One of K is made to face the photosensitive drum 3 and electrostatically ejects toner to develop a toner image on the surface of the photosensitive drum 3.

Further, a transfer drum 9 serving as a transfer material carrier faces the surface of the photosensitive drum 3 in contact with or slightly apart from the surface of the photosensitive drum 3 in the rotational direction of the photosensitive drum 3.
As shown in FIG. 8, the transfer drum 9 has ring portions 9a at both ends,
As shown in FIG. 9, a dielectric sheet 93 which is a transfer material carrying member is attached to the frame 49 in which 9b is connected by the connecting portion 9c.
Is wound in a cylindrical shape, and the transfer charger 10 is arranged on the opposite side of the transfer material holding surface of the dielectric sheet 93 so as to face the photosensitive drum 3.

Further, on the downstream side of the transfer position, an outer charge-eliminating discharger 11 and an inner charge-eliminating discharger 13, which are AC corona dischargers for charge-eliminating, are arranged with a dielectric sheet 93 interposed therebetween. On the upstream side, a suction corona charger 39 as a suction means for electrostatically attracting the transfer material P to the dielectric sheet 93,
The grounded suction rollers 40 are provided to face each other. The suction roller 40 is an urging unit that mechanically and electrostatically holds the transfer material P on the transfer drum 9 in a close contact manner.

The transfer material P is guided to a suction position by a paper feed guide 58 through a pair of registration rollers 6 from a paper feed unit (not shown). Then, the transfer material P is first adsorbed and carried on the dielectric sheet 93 of the transfer drum 9 by the adsorbing means (39, 40). The transfer material P carried on the dielectric sheet 93 is conveyed to a transfer position where the photosensitive drum 3 and the transfer charger 10 face each other by the rotational movement of the transfer drum 9, and the photosensitive drum 3 is transferred.
From then on, four color toner images are superposed and transferred. In the vicinity of the outer and inner charge-eliminating dischargers 11 and 13, an inner side for deforming the separating claw 15 and the dielectric sheet 93 from inside to form a gap between the transfer material P and the dielectric sheet 93. A pressing roller 70 is provided. After the transfer, the transfer material P, which has been discharged by the discharging dischargers 11 and 13, has its inner pressing roller 70 moved in the direction of an arrow B by a driving device (not shown), so that the dielectric sheet 93 is deformed. Is separated from the dielectric sheet 93.

The separated transfer material P is supplied to the fixing rollers 17a and 17b through the conveying device 24, and the toner is heated to mix the colors to fix a full-color image.

Next, the details of the suction roller 40 will be described with reference to FIGS. FIG. 1 shows a suction roller 40 in FIG.
FIG. 2 is a perspective view of the suction roller 40 viewed from the direction of the arrow C, and FIGS.

In FIG. 1, the swing plates 53a and 53b are swingably supported by a support shaft 45 fixed to a body frame (not shown). The suction roller 40 is rotatably supported at one end of swing plates 53a and 53b of the bell crank.

A pressure spring 5 having one end locked to the other ends of the oscillating plates 53a and 53b and the other end locked to a main body housing (not shown).
The oscillating plates 53a and 53b are urged in the direction of the arrow by 4a and 54b, and the suction roller 40 is urged in the direction of the transfer drum 9 accordingly. Friction rollers 59a and 59b are integrally formed at both ends of the suction roller 40, and a driven gear 71 is integrally formed at one end thereof. Cam shaft 61 rotatably supported
The eccentric cams 62a and 62b fixed to the rotary shaft are rotationally driven via a cam shaft 61 by a power source such as a motor not shown. The eccentric cams 62a and 62b are brought into contact with the supporting arms of the oscillating plates 53a and 53b that lock the pressure springs 54a and 54b, respectively, and the eccentric cams 62a and 62b rotate by approximately 180 °, whereby the suction roller 40 is transferred. A state of contacting the drum 9 and a state of separating from the drum 9 are realized.

The scraper base 63 is a scraper swing shaft 64.
It is swingably supported by the swing plates 53a and 53b, and is attached in the direction of the arrow by the scraper pressure springs 65a and 65b (65b not shown) of torsion springs inserted in the scraper swing shaft 64 shown in FIG. It is energized.

A scraper 66 is fixed to the scraper base 63, swings integrally with the scraper base 63, and the edge of one end of the scraper 66 has the suction roller 40 separated from the transfer drum 9 in the state of FIG. It is in contact with the suction roller 40. The scraper base 63 has pins 67a, 67
The abutting rollers 68a, 68b are rotatably supported by b, and the friction rollers 59a, 59b and the abutting rollers 68a, 68b are in contact with the ring portions 9a, 9b forming both ends of the frame 49 of the transfer drum 9, respectively. Is installed in.

The suction drive gear 69 is supported by a main body housing (not shown) and is rotationally driven by a drive source such as a motor (not shown).

When the suction roller 40 is separated from the transfer drum 9, the suction drive gear 69 is arranged at a position meshing with a driven gear 71 fixed to the shaft of the suction roller 40.

Next, the operation of this structure will be described with reference to FIGS. FIG. 2 shows a suction operation state. Since the eccentric cams 62a and 62b are at the retracted lift 0 position, the swing plates 53a and 53b are urged by the pressure springs 54a and 54b, and the friction rollers 59a and 59b in FIG. It contacts the ring portions 9a and 9b of the frame 49. At this time, the abutting rollers 68a and 68b also come into contact with the ring portions 9a and 9b of the frame 49 in the same manner, so that the scraper base 63 resists the scraper pressure springs 65a and 65b and swing plates 53a and 53b.
It swings relative to b, and the end of the scraper 66 separates from the suction roller 40.

In such a state, the suction roller 40
Has no elements that hinder its rotation, so the friction roller 59
a, 59b and the ring portions 9a, 9b of the frame 49 rotate due to friction, and the peripheral speed thereof matches the peripheral speed of the transfer drum 9. Therefore, the speed of the transfer material P does not fluctuate, and therefore during the suction operation. Even if the transfer process is performed at the front end of the transfer material P, the transferred image is not disturbed.

Next, the transfer material P on which the toner image of the first color has been transferred is transferred to the suction roller 40 in order to prevent the already transferred toner from being retransferred to the suction roller 40 before reaching the suction position again. It is necessary to separate it from the drum 9. That is, as shown in FIG. 3, the eccentric cams 62a and 62b are almost
By rotating the rocking plates 53a and 53b against the pressure springs 54a and 54b by rotating them by 80 °, the suction roller 40 is separated from the transfer drum 9. At this time, the abutting rollers 68a and 68b are also attached to the ring portion 9 of the frame 49.
Since it is separated from a and 9b, the scraper pressure spring 65
The edge of one end of the scraper 66, which is urged by the a and 65b and fixed to the scraper base 63, has the suction roller 40.
Abut.

At the same time, the driven gear 71 (FIG. 1) integrally formed at the end of the suction roller 40 is changed to the suction drive gear 69.
Therefore, by rotating the suction drive gear 69 in the direction of the arrow, the suction roller 40 rotates so that the suction roller 40 moves its peripheral surface in the direction opposing the edge of the scraper 66.

Since the rotational load of the suction roller 40 at this time does not affect the transferred image, the contact pressure of the scraper 66, that is, the urging force of the scraper pressing springs 65a and 65b, sufficiently cleans the suction roller 40 by the scraper 66. Can be set so that as a result, the suction roller 4
No cleaning failure of 0 will occur.

In this embodiment, the suction roller 40
Although an example in which the scraper 66 is used as the cleaning means of the above is shown, other cleaning means such as felt and brush may be used as the scraper base 6.
It is needless to say that the same effect can be obtained even if the same operation is performed by fixing to 3.

[Example 2] Example 2 of the present invention will be described below. Note that the description of the same parts as in the first embodiment will be omitted. Although the scraper 66 is attached to the rocking plates 53a and 53b via the scraper base 63 in the above-described first embodiment, the second embodiment is different in that the scraper 66 is fixed, and the other points are the same.

5 and 6, a scraper 66 is fixed to the body frame 75 at one end thereof. In FIG. 5, the eccentric cams 62a and 62b are the lift 0 and the swing arm 5
By the position retracted from 3a and 53b, the suction roller 40 is urged by the pressure springs 54a and 54b to contact the transfer drum 9, and in this state, the scraper 66 is separated from the suction roller 40.

In FIG. 6, when the eccentric cams 62a and 62b rotate about 180 ° from the position of the lift 0 in FIG. 5, the swing plates 53a and 53b swing against the pressure springs 54a and 54b, The suction roller 40 separates from the transfer drum 9 and contacts one end of the scraper 66.
Further, similarly to the first embodiment described in FIG. 1, the driven gear 71 provided at the end portion of the suction roller 40 meshes with the suction drive gear 69 supported by the main body housing, and the suction drive gear 69 causes the suction roller 40 to move. The suction roller 40 is driven to rotate and is cleaned by the scraper 66.

[Example 3] Example 3 of the present invention will be described below. The description of the same parts as those in the first embodiment will be omitted. In FIG. 7, a belt 76 is wound around a driven pulley 72 supported at the end of the suction roller 40 and a drive pulley 74 fixed at the end of the drive shaft 73. The drive shaft 73 is rotatably supported by a main body housing (not shown), and further includes a swing plate 53.
The a and 53b are swingably supported by the drive shaft 73 via bearings 77a and 77b (77b is not shown). Drive shaft 73
Is in the same position as the support shaft 45 of the first embodiment. A one-way clutch 79 is press-fitted into the driven pulley 72.
It is set so that the suction roller 40 is rotationally driven when it is rotated in the direction, and idle when it is rotated in the reverse direction.

The drive shaft 73 is rotationally driven by a rotation transmission means such as a gear provided at an end portion not shown, and the suction roller 40 is rotated via a drive pulley 74, a belt 76, a driven pulley 72, and a one-way clutch 79. Driven.
The rotation speed at this time is set so that the peripheral speed of the suction roller 40 is sufficiently lower than the peripheral speed of the transfer drum 9.

According to this structure, the suction roller 40 is separated from the transfer drum 9 during the non-suction operation,
That is, in the state shown in FIG. 7, the suction roller 40 is driven to rotate in the direction of arrow B, and the suction roller 40 contacting the end of the scraper 66 is cleaned.

Next, as shown in FIG. 2, when the suction roller 40 contacts the transfer drum 9 in the suction operation state, the abutting rollers 68a and 68b contact the transfer drum 9 as in the first embodiment. The scraper 66 is the suction roller 4
Separate from 0.

At this time, the transfer drum 9 is shown in FIG.
Since it is rotating in the direction of arrow C, the suction roller 40 is rotationally driven by the friction rollers 59a and 59b. Here, as described above, the suction roller 40 by the driven pulley 72 is
Is set so that the peripheral speed of the suction roller 40 is lower than the peripheral speed of the transfer drum 9. Further, since the rotational driving force by the friction rollers 59a and 59b acts so as to drive the peripheral speeds of the suction roller 40 and the transfer drum 9 equally, the one-way clutch 79 idles and the suction roller 40 is affected by the rotation of the driven pulley 72. It follows the transfer drum 9 without moving. At this time, since the scraper 66 is separated from the suction roller 40, it does not affect the rotation speed of the suction roller 40.

[0046]

As described above, according to the present invention,
The cleaning means can be brought into contact with or separated from the transfer material urging means,
The transfer material urging means can be brought into contact with and separated from the transfer material carrier.
When the transfer material urging means is separated from the transfer material carrier,
The drive from the drive source is transmitted to the transfer material energizing means, and the transfer material is attached.
When the energizing means comes into contact with the transfer material carrier, it is driven from the drive source.
Motion is not transmitted to the transfer material energizing means.
When the copying material energizing means comes into contact with the transfer material carrier,
The biasing means is rotated by friction with the transfer material carrier,
The cleaning means is separated from the transfer material urging means
When the means is separated from the transfer material carrier,
The step is rotated by the drive source, and the cleaning means is with transfer material
By contacting the biasing means, the cleaning member does not hinder the rotation of the transfer material biasing means while the transfer material biasing means is attracting to the transfer material carrier , thereby preventing image shift.
In addition, it is possible to exert a sufficient cleaning ability in the non-suction operation state. Therefore, dirt such as toner does not accumulate on the transfer material urging means, and dirt does not adhere to the transfer material.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a side view showing a suction operation state in FIG.

FIG. 3 is a side view showing a non-suction operation state in FIG.

FIG. 4 is a vertical sectional view of an image forming apparatus according to a first embodiment of the present invention.

FIG. 5 is a side view showing an operating state of the second embodiment of the present invention.

FIG. 6 is a side view showing an operating state of the second embodiment of the present invention.

FIG. 7 is a perspective view showing a third embodiment of the present invention.

FIG. 8 is a perspective view showing details of a frame of the transfer drum.

FIG. 9 is a perspective view of a transfer drum.

FIG. 10 is a vertical sectional view of a conventional image forming apparatus.

FIG. 11 is a side view showing a suction operation state in the transfer device of the conventional image forming apparatus.

FIG. 12 is a side view of a transfer device of a conventional image forming apparatus in a non-sucking operation state.

FIG. 13 is a perspective view showing a reference example of a transfer drum.

[Explanation of symbols]

1 Development device 3 photosensitive drum P transfer material

─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Takeo Tsunami 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Kenji Takeda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Incorporated (72) Inventor Hisawa Okubo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroshi Hirai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yoshinori Mochida 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hajime Suzuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) Reference Literature JP-A-3-87883 (JP, A) JP-A-4-263279 (JP, A) JP-A-2-163777 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15 / 16 G03G 15/01

Claims (4)

(57) [Claims] 1. A transfer material carrier for supporting a transfer material, a charging means for electrostatically holding the transfer material on the transfer material carrier, and a charging means sandwiching the transfer material carrier. A roller-like transfer material urging means for urging the transfer material toward the transfer material carrier, and a cleaning means for cleaning by contacting the surface of the transfer material urging means. If, in an image forming apparatus having a, the cleaning means movable toward and away from to the transfer material biasing means
And the transfer material urging means is contacted with and separated from the transfer material carrier.
When the transfer material urging means is separated from the transfer material carrier , it is possible.
, The drive from the drive source is transmitted to the transfer material urging means,
When the transfer material urging means comes into contact with the transfer material carrier
Drive from the drive source is transmitted to the transfer material urging means.
Ranakunaru so configured, when the transfer material biasing means in contact with said transfer material carrying member
Means that the transfer material urging means is resistant to friction with the transfer material carrier.
And the cleaning means is rotated by
When the transfer material urging means is separated from the step and separated from the transfer material carrier.
The transfer material urging means is rotated by the drive source.
And the cleaning means contacts the transfer material urging means.
That, the image forming apparatus characterized by. 2. The transfer material urging means is configured to carry the transfer material.
Drive is transmitted to the transfer material urging means by contacting the body
A friction roller is provided, The claim 1 characterized by the above-mentioned.
Image forming device. 3. The transfer material urging means is provided from the drive source.
Driven gear that can be moved in and out of the drive gear that transmits the drive of
Have When the transfer material urging means is separated from the transfer material carrier
The drive gear and the driven gear mesh with each other,
When the biasing means comes into contact with the transfer material carrier, the drive gear is moved.
A. The driven gear and the driven gear are separated from each other.
Alternatively, the image forming apparatus according to claim 2. 4. A drive plug for transmitting drive from the drive source.
With A belt that transmits the drive from the drive pulley, The transfer material urging means transmits the drive from the belt.
Driven pulley and a drive that transmits the drive from the driven pulley.
With a one-way clutch, The image according to claim 1 or 2, characterized in that
Forming equipment.